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  • Springer  (273,481)
  • 1980-1984  (158,275)
  • 1970-1974  (115,206)
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  • 1
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We present a new method for extracting a comprehensive suite of biologically significant parameters from line transect data of coral communities. In addition to the percentage coral cover (the traditionally extracted parameter), the method extracts the population density of the coral colonies, their mean diameter and associated standard deviation and, for adequate data, their size frequency distribution. The method assumes only that the coral colonies form a system of non-overlapping circles in the plane, that the diameters of the circles are random quantities with an unknown distribution function, and that the transects are placed randomly. We test the method on both theoretical and real data to show that it performs as well as, if not better than, current methods in extracting the traditional parameter as well as being able to extract the additional useful parameters indicated. Because the method makes few restrictive assumptions and seems robust when used with field data, we suggest that it has wide application wherever line transects are used for ecological survey. The method is implemented in a Fortran program available from the senior author.
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  • 2
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Previous studies have attempted to quantify the nutritional importance of zooxanthellae to the respiratory requirements of their host, from measurements of the 24 h photosynthesis to respiration ratio. This preliminary study explores an alternative approach by trying to account for the energy fixed in photosynthesis in terms of expenditure, storage and loss. The energy budget so derived for Pocillopora eydouxi suggests that about 51% of the photosynthetically fixed energy is used in respiration, 0.9% in growth and 48% is unaccounted for and presumably lost from the colony. By partitioning the energy budget, it is found that 24% of the respiration and 11% of the energy retained in growth is attributable to the zooxanthellae. It is postulated that nutritionally, a coral is analogous to an aphid in being supplied with a high carbon diet and in being obliged to excrete the excess, probably in the form of mucus.
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  • 3
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The reproductive biology of Goniastrea aspera at Magnetic Island was compared with that of a very similar sympatric species, G. favulus as reported by Kojis and Quinn at Heron Island. The development of gametes was similar in both species, but there was no evidence for an adolescent protandrous period of development in G. aspera such as that recorded for G. favulus at Heron Island. Other reproductive differences between the two species were found in egg size and the mode of spawning. The eggs of G. aspera are smaller and more numerous than those of G. favulus. Goniastrea aspera expelled buoyant packets of eggs and sperm, while G. favulus had sticky sinking eggs which were released separately from the sperm. The spatial pattern of the two species was examined on the reef flat at Magnetic Island to determine whether the observed differences in spawning behaviour and egg buoyancy might have an effect on egg retention and the distribution of adult colonies. The results of this comparison failed to detect any difference in the degree of aggregation of the two species. This is not the result which would be expected if sticky sinking eggs helped retain developing larvae in the vicinity of the adult. These results, together with evidence from a wide range of coelenterates and observations on the larvae of G. aspera point to post spawning larval behaviour as the most likely factor in determining where these species will settle.
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  • 4
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Fish larvae from horizontal plankton tows along a single transect near outer ribbon reefs of the Great Barrier Reef in spring 1979 and summer 1980 had persistent distributional patterns. Larvae were identified to family and divided into young (preflexion) and old (postflexion) larvae, thus giving 28 taxa abundant enough for analysis. Non-uniform larval distributions were found for 81% of the 16 reef fish taxa with non-pelagic eggs, but for only 17% of the six reef fish taxa with pelagic eggs. Most differences in larval concentration were between the lagoonal and seaward sides of the reef. Only tripterygiid larvae had highest concentration just seaward of the reef, while larvae of 12 reef and three oceanic fish taxa occurred in highest concentrations on the lagoonal side of the reef. In five taxa of reef fishes, higher larval concentrations were found in the lagoonal backreef compared with the mid-lagoon habitat; but the reverse was not found in any taxon. Eleven taxa had indeterminate distributions, (i.e. no difference in concentration between stations). Mechanisms responsible for the distribution remain unknown, but we suggest that the view which considers fish larvae to be passively-drifting particles is unjustified without more information on larval behaviour.
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  • 5
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The effect of used drilling muds on coral health was examined by monitoring changes in calcification rate and soluble tissue protein concentration in the coral Acropora cervicornis. Exposure to 25 ppm (v/v) of one mud for 24 h reduced calcification rate in the growing tips by as much as 62%. In recovery experiments, corals were exposed to drilling muds for 24 h; some of them were allowed to recover in clean seawater for 48 h. After the 24-hour exposure, calcification rates were significantly less than those of the controls. After a 48-hour recovery period, calcification rates returned to control levels for one mud but were still significantly below control levels for another. The results indicate that the capacity for recovery after exposure cannot be predicted from the results of experiments on exposure only. Recovery capacity must be independently verified for all studies on the effects of short-term exposure to drilling muds.
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  • 6
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    Electronic Resource
    Springer
    Coral reefs 2 (1984), S. 226-226 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 3 (1984), S. 51-57 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Monthly linear extension and calcium carbonate accretion were measured over a year in the Caribbean staghorn coral, Acropora cervicornis. X-radiographs were made of cross sections of branches to analyze radial growth. Correlations were made between parameters of skeletal growth and four environmental parameters monitored over the same sampling periods: temperature, daylight hours, sun hours, plankton abundance. The results indicate that linear extension does not change during the year with the possible exception of April. It is suggested that temperatures outside an optimal range (ca. 26°–29°C for staghorn Acroporas) might cause a decrease in linear extension, however. Specific accretion (mg. mm-1) does show significant variations through the year. Calcium carbonate accretion (mean specific accretion times mean linear extension, mg. tip-1) is most strongly correlated with number of sun hours. A comparison is made between diel patterns of extension and accretion and longer term measurements. It is suggested that the accretion process is probably most influenced by some activity influenced by light. There are no annual growth bands in X-radiographs of cross-sections of the branches of A. cervicornis. This may result from secondary infilling in the skeleton.
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  • 8
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Starting in June 1983, 25 species of hermatypic corals, gorgonians, hydrocorals, anemones and zoanthids in the San Blas Islands, Panama, began showing signs of a loss of colour leading in some cases to a white “bleached” appearance. Histologic examination of six coral species indicated that bleaching was associated with drastic reductions in the density of zooxanthellae and with the atrophy and necrosis of the animal tissue. The severity of the bleaching varied among species and many species were unaffected. The species most extensively affected were: Agaricia spp., which became completely bleached and frequently died; Montastraea annularis which bleached and continued to survive; and Millepora spp. which bleached white but quickly regained their colouration. Shallow reefs dominated by Agaricia spp. suffered the most extensive bleaching. At one site, Pico Feo, 99% of the Agaricia (32% of the living cover) was bleached. On fore reers, which were dominated by Agaricia spp. and M. annularis, the proportion of M. annularis bleached ranged from 18 to 100% and that of Agaricia spp. from 30 to 53%. Transects at Sail Rock and House Reef were surveyed in August 1983 and January 1984. At those sites, 53% of the Agaricia cover died between August and January. The remaining living cover of Agaricia and of all other species exhibited normal colouration in January. Salinity and temperature were monitored every second day at 4 m depth between May 10 and August 28, 1983 at one of the localities. Bleaching was first observed within two weeks of a 2 °C rise in temperature which occurred in late May 1983. Temperatures remained at or above 31.5 °C for the following 3 weeks and were at or above 30 °C for an additional 4 weeks. The bleaching of corals in the San Blas was most likely due to those elevanted temperatures.
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  • 9
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A benthic faunal study was carried out in the tidal area of Mactan Island (Cebu, Philippines). The area was subdivided along a transect from the beach to the reef according to benthic assemblages. The sediments are largely composed of calcareous skeletal remains of the indigenous biota and surrounding calcareous rocks. The content of protein and carbohydrates of the sediment was estimated, providing an approximation of organic matter in terms of feeding efficiency. Total number of zoobenthos, both as regards the sediment samples and as to the epifaunal communities associated with seaweeds, is rather uniformly distributed justifying the 95% confidence level (P〉0.05). Distinct differences are apparent in abundance values of individual taxa. Although the study area showed the expected distribution pattern, with dominance of Nematoda (39%) living in sediment and Harpacticoida (36–66%) dwelling on Thalassia and algae, Polychaeta reveal a dominant attraction to both these habitats. The reasons for this phenomenon are discussed in relation to the absolute lack of macrofaunal predators The zoobenthos adjust their distribution and activity to fluctuating conditions of the environment. Light is mainly suggested as stimulating diel migration activities of the benthic fauna, moving upwards from the sediment to the algae and Thalassia during daytime. In a field experiment the zoobenthos was investigated for digestion activity over a diurnal cycle. The results reveal that feeding activity of zoobenthos follows a diel cycle showing maximum activity during the morning and evening obviously influenced by changes of light.
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  • 10
    ISSN: 1432-0983
    Keywords: Chromosome map ; Yeast ; Schizosaccharomyces pombe ; Gene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genetic map of the nuclear genome of the fission yeast Schizosaccharomyces pombe has been extended by mitotic and meiotic mapping data. A total of 158 markers are now assigned to the three linkage groups known in this organism, and 118 of them have been located on the corresponding chromosome map. Chromosome II and III each consist of one linkage group. There is some indication that the two large fragments which define chromosome I are meiotically linked, but the linkage observed is significant at the P = 0.05 level only. The length of the map is at least 1,700 map units, corresponding to an average of about 8 kilobases per map unit. The latter figure is comparable to the one obtained for intragenic recombination in the sup3 gene (Hofer et al. 1979). The basic frequency of gene conversion as measured for 21 genes varies according to a distribution of Poisson (with a modal value of 0.6% conversion per meiosis and per gene), in sharp contrast with Saccharomyces cerevisiae (Fogel et al. 1980) and Ascobolus immersus (Nicolas 1979). This may reflect the rarity of gene or region-specific rec alleles in S. pombe and may be related to the homothallism of this organism.
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  • 11
    ISSN: 1432-0983
    Keywords: Schizosaccharomyces pombe ; Purine catabolism ; Purine hydroxylase ; Allantoinase ; Allantoicase ; Uricase, Ureidoglycollase and urease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Purines such as hypoxanthine, xanthine, uric acid, allantoin and allantoic acid serve as sole nitrogen sources for the yeast Schizosaccharomyces pombe. A number of classes of mutants unable to use purines have been isolated and genetically analysed. Mutants in the urol gene lack uricase, all1 lack allantoinase, ala1 lack allantoicase whilst in ure1, ure2, ure3 and ure4 genes lack urease activity. Mutants in four hyp genes are unable to convert hypoxanthine to uric acid whilst mutation in xan1 results in impaired growth with xanthine. hyp5 strains are unable to convert both hypoxanthine and xanthine to uric acid. The mutations are recessive and none of the loci are linked to each other. The possible catalytic steps involved are discussed.
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  • 12
    ISSN: 1432-0983
    Keywords: Yeast mitochondria ; Mapping of mutations ; Mitochondrial DNA sequence ; Mitochondrial ATPase complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A genetic and molecular analysis of the oli2 region in mitochondrial DNA of Saccharomyces cerevisiae has been carried out. The oli2 gene codes for subunit 6 of the mitochondrial ATPase complex. We have isolated a series of 41 mit −, temperature sensitive and oligomycin resistant mutants containing mutations located in the oli2 region. In addition the sequence in wild type mtDNA of 2820 nucleotides covering the oli2 gene and its flanking regions has been determined. A library of petite mutants which have various deletion end points in the oli2 region has been used to generate marker rescue data that allow the assignment of each mit −, temperature sensitivity and oligomycin resistance mutation to one of seven uniquely ordered genetic groups. The following physical reference points allow the limits of the physical map positions of a number of the genetic groups to be established: DNA sequence data have been obtained for three of the petites so as to determine unambiguously their relevant deletion end points and the base substitution constituting the mtDNA sequence change in one oligomycin resistant mutant [oli2-23r] has been determined to lie at nucleotide +523 of the oli2 coding region. One group of mit − mutations (group N) are known to map within the aap1 gene that is found some 700 bases upstream of the oli2 gene, and which codes for subunit 8 of the mitochondrial ATPase complex. Mutations in the remaining six groups (A-F) map within (or very close to) the coding region of the oli2 gene. Various features of the DNA sequence in and around the oli2 gene are considered, including protein coding regions, sequence divergence in the A,T-rich spacer regions, properties of G,C-rich clusters, and potential ribosome binding sites. Consideration of the transcriptional map of this region of mtDNA suggests that an abundant 4,500 nucleotide transcript may represent the first defined example of a dicistronic messenger RNA in yeast mitochondria carrying distinct coding regions (aap1 and oli2) for two different proteins.
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  • 13
    ISSN: 1432-0983
    Keywords: Killer-Torulopsis yeast ; Cytoduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have used cytoduction and protoplast fusion to characterise the killer trait in Torulopsis glabrata. Killer trait could not be transferred by cytoduction to a non-killer strain of T. glabrata suggesting that the determinant(s) is/are not present in the cytoplasm. Consistent with this interpretation is the observation that all fusion products, where chromosomes of both the parents are represented, are killers. Non-killer segregants could be isolated from fusion products after treatment with benlate suggesting that loss of the trait is associated with non-disjunction and loss of a chromosome.
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  • 14
    ISSN: 1432-0983
    Keywords: Chloroplast ; Ribosomal proteins ; Spinacia oleracea ; Phosphorylation ; Protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have characterized the ribosomal proteins from Spinacia chloroplasts using two-dimensional gel electrophoresis. The 30S and 50S subunits contain 23–25 and 36 ribosomal proteins, respectively. In contrast to prokaryotic ribosomes, chloroplast ribosomes contain at least one (and possibly two) phosphorylated ribosomal proteins. Isolated chloroplasts synthesize in the presence of (35S) labeled methionine and cysteine at least seven 30S and thirteen 50S ribosomal proteins which are assembled into (pre)ribosomes. This suggests that about one third of the chloroplast ribosomal proteins is encoded by the chloroplast DNA itself. The identity of several labeled proteins in the two-dimensional gel electrophoretic patterns which did not comigrate with stained chloroplast ribosomal proteins is discussed.
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  • 15
    ISSN: 1432-0983
    Keywords: Pichia guilliermondii ; Regulatory mutants ; Riboflavin transport ; α-Glucosidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The method for a positive selection of Pichia guilliermondii yeast mutants which constitutively synthesize riboflavin (RF) permease has been developed. A genetic analysis revealed two regulatory genes of negative action (RFP80, RFP81) and one gene of positive action (RFP82); mutations in these loci determined the ability to synthesize RF permease in the medium without an inducer (α-glucosides). The constitutive mutants with cold-sensitive products of RFP80 and RFP81 genes were isolated. Interafelic complementation within RFP80 locus as well as restoration of the wild (inducible) phenotype in some hybrids between recessive rfp80 mutants and dominant RFP82 c mutants were observed. These data suggest a protein structure of products of identified regulatory loci and a direct interaction of the products of RFP80 and RFP82 genes. A meiotic segregants unable to synthesize RF permease in the inducer-containing media (genotype rfp82) were isolated by means of intragenic recombination in RFP82 locus. Epistasis-hypostasis test showed that gene RFP82 acted after gene RFP80. RFP80, RFP81 and RFP82 loci are involved in regulation of biosynthesis of both RF permease and α-glucosidase. The model for action of RFP80 and RFP82 gene products in the expression of RF permease and α-glucosidase structural genes of P. gulliermondii is presented.
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  • 16
    ISSN: 1432-0983
    Keywords: Yeast ; Mitochondrial DNA ; Antibiotic resistance mutations ; Suppressor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Strains that are genotypically sensitive to chloramphenicol and also contain one of the nuclear suppressors of mitochondrial chloramphenicol resistance (Waxman et al. 1979) were constructed. A manganese mutagenesis on such a strain produced chloramphenicol resistant mutants, most of which resulted from mutations in nuclear genes. These mutants may be either dominant or recessive, and they probably do not code for membrane proteins. The few mitochondrial mutants fall into several classes, but all result from mutations in the 21S rRNA gene. The suppressor allele effectively prevents the appearance of the most common group of mitochondrial mutants (those that map at cap1), and thereby enhances the selection of novel mutants in the region.
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  • 17
    ISSN: 1432-0983
    Keywords: Senescence ; Podospora ; Mitochondrial DNA ; Ethidium Bromide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of ethidium bromide (EB) which is known to be able to “rejuvenate” senescent mycelia in Podospora anserina, has been investigated at the level of the mitochondrial DNA (mtDNA) by restriction analysis and molecular hybridization. While senescent mycelia display a very low growth ability and gross mtDNA modifications (tandem amplification of short sequences and disorganization of the mitochondrial chromosome: deletion of large sequences), the rejuvenated mycelia display a normal life span and contain a mtDNA in all respects identical to that of wild type mycelium (neither circular molecules nor amplified fragments could be detected). These results demonstrate a strict correlation between the senescent state and the presence of amplified mtDNA and suggest that EB rejuvenation could proceed by an efficient selection of intact mitochondrial chromosomes still present in senescent cultures.
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  • 18
    ISSN: 1432-0983
    Keywords: Translation suppression ; Regulatory genes ; Aspergillus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The areA gene of Aspergillus nidulans is a one of the better studied eukaryotic wide domain regulatory genes, necessary for the expression of most structural genes involved in the utilization of a wide variety of nitrogen sources (Arst and Cove 1973; Arst 1983). Here we report the isolation and properties of areA alleles suppressible by translational suppressors (Roberts et al. 1979). Thus we show formally that the areA gene specifies a protein rather than an RNA product and we show that it is possible to generate by external suppression areA gene products with modified properties.
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  • 19
    ISSN: 1432-0983
    Keywords: Petunia hybrida chloroplast DNA ; E. coli minicells ; rbcL gene ; Nucleotide sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Petunia hybrida rbcL gene was identified and located on the physical map within the Sall S9 fragment of the Petunia hybrida cpDNA by heterologous hybridization with the cloned rbcL gene of spinach (pSoc3BE148). In E. coli minicells harbouring the S9 fragment inserted into pBR322, the rbcL polypeptide is synthesized as was shown by molecular weight determination, immunoprecipitation and proteolytic digestion. However, the size of the rbcL polypeptide synthesized in minicells appeared to be dependent on the orientation of the S9 fragment in pBR322. In minicells harbouring the S9 fragment inserted into pBR322 in the clockwise orientation the molecular weight of the rbcL polypeptide is approximately 53 kD, whereas in minicells harbouring the S9 fragment in the opposite orientation, the rbcL polypeptide synthesized has a molecular weight of 52 kD. The difference in molecular weight of the two rbcL polypeptides is the result of transcription and translation into the flanking pBR322 sequences. This is due to the absence of the terminal part (6 codons), including the translation stop codon, of the rbcL gene on the cloned S9 fragment as was determined by nucleotide sequencing. The observed expression of the cloned part of the rbcL gene of Petunia hybrida indicates that the E. coli minicell system can be used as a suitable and convenient system for the identification and physical mapping of chloroplast genes. Comparison of the sequence of the untranslated 3′-end of the rbcL gene of Petunia hybrida with that of Nicotiana tabacum revealed a striking similarity of the region in which stem and loop structures can be formed that are most likely involved in termination of transcription of the rbcL gene. This region appears to be highly conserved in the rbcL genes of P. hybrida, N. tabacum, S. oleracea and Z. mays.
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  • 20
    ISSN: 1432-0983
    Keywords: Regulation ; Alcohol dehydrogenases ; Aspergillus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Aspergillus nidulans there are two alcohol dehydrogenases. In the presence of ethanol, alcohol dehydrogenase I (AHH I) is induced and alcohol dehydrogenase II (ADH II) is repressed. ADH I and ADH II have molecular weights of 39,000 and 36,000 respectively. At least ADH I is under the control of alcR, a transacting regulatory gene that is adjacent to alcA (the structural gene for ADH I, Pateman et al. 1983). Mutations in the alcR regulatory gene result in non inducibility of ADH I specific mRNA. Extreme alcA and alcR mutations result in derepressed levels of ADH II, and it is not clear whether alcR controls ADH II directly or through its control of ADH I synthesis. Both enzymes are subject to carbon catabolite repression. Induction of ADH I and ADH II operates at the level of synthesis or processing of mRNA.
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  • 21
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    Electronic Resource
    Springer
    Current genetics 8 (1984), S. 261-264 
    ISSN: 1432-0983
    Keywords: Phycomyces ; Photocarotenogenesis ; Quantitative complementation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mutants of Phycomyces defective in carotene regulation were studied in relation with the photo carotenogenic response. Quantitative complementation analyses revealed that carC, carA and carS mutations are recessive and complement for this photoresponse in carC * carA and carC * carS heterokaryons. A scheme of the regulation of carotenogenesis by light is proposed.
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  • 22
    ISSN: 1432-0983
    Keywords: DHF Reductase ; Cloning ; Trimethoprim ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The dihydrofolate reductase gene of Saccharomyces cerevisiae has been isolated by selection of trimethoprim resistant Escherichia coli transformed with a gene bank of yeast DNA in plasmid pBR322. From 9.2 kilobase pair BamHI DNA fragment this gene has been localized to a 1.76 kb fragment, the restriction map of which appears different from those reported for the E. coli and the mouse dihydrofolate reductase genes. The enzyme encoded by the chimeric plasmid was established as yeast dihydrofolate reductase by its sensitivity to antifolates in vivo through growth studies and in vitro by enzyme assay. Since, the expression of this gene occurs independent of its orientation within the chimeric plasmid, the 1.76 kb fragment may contain functional regulatory sequences in addition to the structural sequences for yeast dihydrofolate reductase.
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  • 23
    ISSN: 1432-0983
    Keywords: β-isopropylmalate dehydrogenase ; Leucine B ; Leucine 2 ; Cephalosporium acremonium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A Cephalosoporium acremonium gene library has been constructed using cosmid vector pYcl. After transformation of E. coli leuB strain JA221 with cosmids isolated from this gene library a cosmid (pCeleuB43) was isolated which complements the leucine auxotrophy of JA221. The same cosmid is also able to complement a leu2 strain of S. cerevisiae. The leuB and leu2 genes both code for β-isopropylmalate dehydrogenase. The complementation of a leuB E. coli strain and a leu2 S. cerevisiae strain strongly suggests that the analogous gene from C. acremonium has been isolated.
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  • 24
    ISSN: 1432-0983
    Keywords: mRNA stability ; Nonsense mutant ; Eukaryotic transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genetic map of 27 mutants of the URA1 yeast gene has been established by meiotic recombination and 16 nonsense mutations characterized. The half life of URA1 mRNA was determined by two independent methods in the wild-type and in two ochre mutants localized at each extremity of the genetic map. A halflife of 15 min was found for the wild-type and for one of the ochre mutants. This half-life was radically reduced in the other ochre mutant whereas the instantaneous rate of its mRNA synthesis remained constant. After subcloning various endonucleolytic fragments the coding sequence of the URA1 gene was restricted to a 1.65 kb fragment within a 5.7 kb yeast DNA segment. Direct visualization of the URA1 mRNA by Northern hybridization of denatured RNA with a URA1 specific DNA probe revealed a length of 1.5 kb.
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  • 25
    ISSN: 1432-0983
    Keywords: Chloroplast DNA ; Pearl millet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chloroplast DNA from pearl millet (Pennisetum americanum) was used to construct recombinant plasmids. These plasmids contained 97 kilobase pairs of unique DNA sequences. The chloroplast DNA fragments in these plasmids were mapped with the restriction endonucleases SalI, SphI, XhoI, BglI and HpaI. The technique of overlapping hybridization or chromosome walking was used to orient these DNA fragments on a restriction endonuclease map of the chloroplast genome. The size of the chloroplast DNA from pearl millet was estimated in this fashion to be 127–138 kilobase pairs. Twenty one kilobase pairs of the cloned DNA fragments were represented twice on the genome as inverted repeats. Thus, the recombinant plasmids which were isolated contained approximately 86–93% of the nucleotide sequences in the chloroplast genome of pearl millet. Previously characterized cloned chloroplast DNA sequences from other plants were used as hybridization probes to locate the genes for the large subunit of ribulose 1,5-bisphosphate carboxylase, the β-coupling factor of ATPase and the 32 kilodalton polypeptide of photo system 11 on the restriction endonuclease map of the pearl millet chloroplast genome.
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  • 26
    ISSN: 1432-0983
    Keywords: Petunia hybrida chloroplast DNA ; E. coli minicells ; ATPsynthase ; Gene mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Escherichia coli minicells harbouring the cloned restriction fragment Sall S9 from P. hybrida chloroplast DNA synthesize the beta and epsilon polypeptide subunits of the CF1 component of the chloroplast ATPsynthase complex. The polypeptides were identified by molecular weight determination and immunoprecipitation. The position of the atpB and the atpE gene, encoding respectively the beta and epsilon subunit, on the Sall S9 fragment was determined in more detail by studying polypeptide synthesis directed by subclones of the S9 fragment in E. coli minicells. The atpB and atpE genes are located close to the rbcL gene, the distance between the rbcL gene and atpB gene being approximately 770 bp. Analysis of the expression of subclones of the S9 fragment in E. coli minicells also revealed that the atpE gene can be transcribed and translated independently of the expression of the atpB gene. The location of the genes coding for the alpha subunit (atpA gene) and the proteolipid subunit III of CF0 (atpH) of the ATPsynthase complex on the physical map of P. hybrida cpDNA was determined by hybridization of restriction enzyme digests of petunia cpDNA with cloned cpDNA fragments from Spirodela and wheat, containing internal parts of respectively the atpA and the atpH gene. The two genes map close together within a region of 5.2 kbp on the physical map of P. hybrida cpDNA. The distance between the atpA gene and the atpB and atpE genes is approximately 42 kbp.
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  • 27
    ISSN: 1432-0983
    Keywords: Podospora anserina ; mt plasmid ; DNA sequence ; Mobile intron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the ascomycete Podospora anserina strain ageing (senescence) is caused by a mitochondrial plasmid. In juvenile mycelia it is an integral part of the mtDNA and becomes liberated during ageing. The nucleotide sequence of this plasmid and of its flanking regions was determined. It consists of 2,539 by and contains an un identified reading frame (URF) originating in the adjacent mtDNA upstream of excision point 1. Within the URF a putative 48 by autonomously replicating sequence (ars) was identified. At both excision sites of the plasmid there are two short nonidentical interrupted palindromes and a few base pairs apart from these palindromes, both upstream and downstream, two short inverted repeats are localised. The experimental data make it evident that the mt plasmid is an intron of the cytochrome c oxidase gene (subunit I) which may be excised at the DNA level and thus become the mobile infective agent causing senescence. The concept of this mobile intron and current hypotheses concerning the relationship between introns and transposons are stressed.
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  • 28
    ISSN: 1432-0983
    Keywords: Phytophthora infestans ; mtDNA ; Phatotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitochondrial DNA (mtDNA) of Phytophthora infestans has been isolated and preliminarily characterized. It has a low GC content of about 22.4% which is distinctly different from that of nuclear DNA (51 %). This property has been used to separate both DNA species in the presence of 4′,6-diamidine-2-phenylindole (DAPI) in CsCl density gradients. The use of cetyl triammonium bromide (CTAB) for extraction of DNA significantly reduced its degradation. The base distribution of the mtDNA shows a limited intramolecular heterogeneity. The molecule contains 36.2 ± 0.3 kb as revealed by endonuclease digestion and seems to be circular as shown by restriction mapping. No differences were found in restriction patterns between mtDNAs from various pathotypes.
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  • 29
    ISSN: 1432-0983
    Keywords: Sugar beets ; Cytoplasmic male sterility ; Mitochondrial and chloroplast DNAs ; Restriction endonucleases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitochondrial (mt) and chloroplast (ct) DNAs were prepared from normal (N) and male sterile (S) cytoplasmic lines of sugar beet. The DNAs were cleaved with BamHI, EcoRI, HindIII and SalI enzymes, and the resultant fragments were fractionated by agarose gel electrophoresis. The results showed that N and S cytoplasms contained distinct mtDNA. Although most of the DNA fragments were common to these two cytoplasms, each cytoplasm was readily characterized by bands specific to that cytoplasm. In addition, these distinctive cleavage patterns were invariant in different nuclear backgrounds. In contrast to the marked variation in mtDNA, restriction fragment analyses of ctDNA demonstrated little difference between both cytoplasms. Only HindIII digestion showed one band missing in the S genome. The data presented here provides circumstantial evidence for mitochondrial involvement in the inheritance of cytoplasmic male sterility in sugar beet.
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  • 30
    ISSN: 1432-0983
    Keywords: Yeast mitochondrial DNA ; Maturase-like sequences ; End-of-Messenger signal ; Frameshifts ; GC clusters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary By completing and correcting the sequence of a 1.8 kb DNA segment downstream of the oxi2 gene of Saccharomyces cerevisiae, a long, potentially coding sequence (“RF2”) has been identified. The sequence is rather closely related to the RF1 open reading frame, downstream of the oxil gene, and, further, to the major family of intronic open reading frames. The RF2 open reading frame is not continuous, however, for it is interrupted by two GC clusters, both of which ultimately result in a −1 frameshift. Comparison with RF1 reveals a third insertion. This is centered on an oligo nucleotide, AATAATATTCTTA, which is found (sometimes in a slightly modified form) downstream of ten proven or suspected protein coding genes, including RF1 and RF2, and is known to terminate the apocytochrome b messenger RNA. It is suggested from the known distribution of this putative “end-of-messenger” signal, that it could play an essential part in controlling the expression of several minor proteins, both intronic and non-intronic. The possibility of the RF2 sequence being functional in spite of its interruptions is also discussed.
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  • 31
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; 5-aminolevulinate synthase ; Cloned gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have cloned the structural gene HEM1 for 5-aminolevulinate (ALA) synthase from Saccharomyces cerevisiae by transformation and complementation of a yeast hem1–5 mutant which was previously shown to lack ALA synthase activity (Urban-Grimal and Labbe Bois 1981) and had no immunodetectable ALA synthase protein when tested with yeast ALA synthase antiserum. The gene was selected from a recombinant cosmid pool which contained wild-type yeast genomic DNA fragments of an average size of 40 kb. The cloned gene was identified by the restauration.of growth on a non fermentable carbon source without addition of exogenous ALA. Sub cloning of partial Sau3A digests and functional analysis by transformation allowed us to isolate three independent plasmids, each carrying a 6 kb yeast DNA fragment inserted in either orientation into the single BamHI site of the vector pHCG3 and able to complement hem1–5 mutation. Analysis of the three plasmids by restriction endonucleases showed that HEM1 is contained within a 2.9 kb fragment. The three corresponding yeast trans formants present a 1, 2.5 and 16 fold increase in ALA synthase activity as compared to the wild-type strain. The gene product immunodetected in the transformant yeast cells has identical size as the wild-type yeast ALA synthase and its amount correlates well with the increase in ALA synthase activity.
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  • 32
    ISSN: 1432-0983
    Keywords: Spheroplast and lithium chloride transformation ; Mitotic homozygotization ; Polyploid transformants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Spheroplast fusion induced by polyethylene glycol often occurs during transformation of yeast spheroplasts. It leads to the appearance of polyploid transformants. We have developed a method of discriminating between haploid and polyploid transformants, based on qualitative comparison of the frequency of mitotic homozygotization for a recessive marker, lys2, in diploid and polyploid hybrids of transformants crossed with a tester haploid bearing lys2. We have used this method to compare the frequency of appearance of polyploids during transformations of spheroplasts and of intact cells using lithium chloride in the strain DC5. Polyploids constitute from 15% to 74% of transformants after transformation of spheroplasts. In lithium chloride transformation polyploids arose in only one of four experiments and constituted 9% of transformants.
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  • 33
    ISSN: 1432-0983
    Keywords: Antisuppression ; Suppression ; tRNA ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of a previously isolated antisuppressor mutation from bakers' yeast, that reduced the efficiency of the tyrosine-inserting ochre suppressor, SUP7-o, on other tyrosine-inserting ochre suppressors has been determined. As expected, the antisuppressor mutation, mod5-1, restricted the capacity of all eight tyrosine-inserting ochre suppressors to suppress nonsense mutations. Based on the suppression of five ochre alleles in the presence of mod5, the eight class I suppressors can be grouped into three subclasses. The most efficient subclass had only one member, SUP4-o. Members of the second group included SUP2-o, SUP3-o, SUP7-o, and SUP8-o. The third and least efficient subclass included SUP5-o, SUP6-o, and SUP1 1-o. These differences in efficiencies are a function of the relative expression of the eight genes encoding tRNATYR.
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  • 34
    ISSN: 1432-0983
    Keywords: Fission yeast ; Drug resistance ; Lipid and sterol composition ; Membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The whole cell lipid and sterol content of the drug resistant strains cyh1, cyh3 and cyh4 was compared with that of wild type by thin layer and gas liquid chromatography and by UV spectrophotometric analysis. The cyh3 and cyh4 strains had a decreased content of the unsaturated 18:1 fatty acid oleic acid, a decreased content of ergosterol and an increased content of 24,28 dehydroergosterol with respect to wild type. The cyh1 strain, however, only showed a decreased content of ergosterol and an increased content of 24,28 dehydro-ergosterol when compared to wild type.
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  • 35
    ISSN: 1432-0983
    Keywords: Iso-1-cytochrome c ; Saccharomyces cerevisiae ; Heme ; Transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A Saccharomyces cerevisiae mutant (hem1 cycl-1) was transformed with plasmids bearing a chromosomal centromer (CEN3) and a 2 μm DNA replication origin. In one of the plasmids a functional CYC1 gene was present, in a second plasmid an XhoI fragment located between bases -245 and -678 upstream from the translation initiation codon had been deleted, in a third plasmid this region had been inverted. Results of hybridization experiments carried out with mRNA isolated from heme-deficient and heme-containing transformants indicated that heme controls transcription of the CYC1 gene and that DNA sequences located within the upstream XhoI fragment are involved in activation of the gene by heme.
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  • 36
    ISSN: 1432-0983
    Keywords: Protoplast fusion ; Yeast ; Yarrowia lipolytica ; Kluyveromyces lactis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Prototrophic hybrids have been obtained by the fusion of auxotrophic haploid strains of the two yeasts Yarrowia (Saccharomycopsis) lipolytica and Kluyveromyces lactis. The hybrid fusants had a colonial morphology intermediate between that of the two parent strains, were uninucleate, and contained an approximately diploid amount of DNA per cell. The growth rates of all the fusants on a minimal glucose medium were slower than those of the two parents. Two of the fusants studied could utilise a novel range of carbon sources. All of these data suggested that the hybrids contained a diploid nucleus formed by the fusion of the two haploid parental nuclei. However, analytical CsCl density gradient centrifugation demonstrated that the nuclear DNA of the fusants was derived almost entirely from the Y. lipolytica parent. Moreover, an examination of the protein constitution of the fusants by two-dimensional gel electrophoresis showed that their protein patterns were indistinguishable from that of Y. lipolytica. Two possible mechanisms for the formation of a diploid nucleus containing DNA derived almost entirely from one of the haploid parents are discussed.
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  • 37
    ISSN: 1432-0983
    Keywords: Sordaria ; Synaptonemal complex ; Translocation ; Linkage groups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Reconstruction of serially sectioned zygotene and pachytene nuclei has allowed, by measuring the lengths of synaptonemal complexes, an assignment of the 7 linkage (LG) groups to the 7 chromosomes in the fungus Sordaria macrospora. The 7 LG have been established using 19 mutants showing low second division segregation frequencies. Eight chromosomal rearrangements mapped on the 7 LG were used to identify the chromosomes involved. The following one to one assignment of the 7 LG to specific chromosomes was obtained: LG a: chromosome (chr) 1, LG b: chr5, LG c: chr6, LG d: chr7, LG e: chr4, LG f: chr3 and LG g: chr2 (the chromosome carrying the nucleolus organizer region).
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  • 38
    ISSN: 1432-0983
    Keywords: Yeast ; Ethidium bromide ; Meiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ethidium bromide was found to inhibit nuclear and mitochondrial DNA synthesis during meiosis which resulted in the inhibition of meiotic gene conversion and sporulation and was also lethal. Protection from the effects of ethidium bromide on meiotic gene conversion and survival was found to coincide with DNA synthesis, but it is possible that protection from sporulation inhibition occurs only later in meiosis.
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  • 39
    ISSN: 1432-0983
    Keywords: Neurospora ; Transformation ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new, rapid, efficient and reliable method for transforming Neurospora crassa is described. In this procedure, germinated conidia are treated with lithium acetate, then incubated with DNA, followed by exposure to polyethylene glycol and then a brief heat shock, prior to plating on selective medium. Optimal conditions to achieve a high transformation rate are reported. Transformation can be obtained with both circular and linear plasmid DNA and also with genomic DNA. Although the rate is substantially decreased, transformation was also obtained with relatively impure DNA preparations, such as that made via rapid “miniprep” procedures. This transformation technique is simple and reliable and provides a considerable savings in time and materials.
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  • 40
    ISSN: 1432-1017
    Keywords: Band 3 ; melittin ; phospholipase A2 ; erythrocyte ; transient dichroism ; rotational diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The rotational mobility of band 3, a protein constituent of the human erythrocyte membrane, was measured by observing the flash-induced transient dichroism of the triplet probe eosin maleimide. In the presence of melittin, a pharmacologically active polypeptide from honey bee (Apis mellifera) venom, a dose-dependent loss of rotational mobility was detected. With acetylated melittin, the ability to immobilise is reduced. Succinylated melittin, however, is devoid of immobilising activity. The possible relevance of these findings to the normal mode of action of melittin was examined by comparing the relative abilities of the native, acetylated and succinylated melittins to lyse erythrocytes and synergise with phospholipase A2, another constituent of bee venom. For both these properties, the order of effectiveness is native melittin 〉 acetyl melittin 〉 succinyl melittin = 0, the same as their order of effectiveness in immobilising band 3. A mechanism is proposed in which melittin is anchored in the membrane by its hydrophobic N-terminus, while its cationic C-terminal moiety binds to negatively charged residues on membrane proteins. This leads either directly or indirectly to protein aggregation and hence loss of mobility. From a detailed comparison of the different effects of the melittin derivatives, it is concluded that melittin may function in vivo by aggregating membrane proteins in order to allow phospholipase A2 to gain access to the membrane bilayer and commence catalysis.
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  • 41
    ISSN: 1432-1017
    Keywords: Interfaces ; phospholipid monolayers ; phase transitions ; fluorescence microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The phase diagram of monolayers of l-α-dimyristoyl phosphatidic acid has been studied by fluorescence microscopy. For pressures corresponding to the nearly horizontal slope in the pressure area diagram the growth of crystalline platelets can be observed. They are of dendritic nature; their sizes can be controlled via pressure, compression speed, temperature and pH, and increased up to 100 μm. Due to repulsive interaction a hexagonal arrangement of crystalline platelets can be established. It is shown that the textures do not depend on the dye probe for concentrations below 3 mol%. On the other hand via incorporation of impurities in concentrations of about 1 mol% the coexistence of lipid and solid phases can be controlled. Since, for a constant surface pressure, this coexistence can be maintained, these monolayers are suitable model systems to study the interactions of proteins and vesicles with coexisting fluid and solid membrane areas.
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  • 42
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 11 (1984), S. 43-50 
    ISSN: 1432-1017
    Keywords: Flux measurement ; photobleaching ; fluorescence microphotolysis ; erythrocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Fluorescence microphotolysis — widely employed for diffusion studies — can be used to measure transfer (flux) of fluorescent solutes through membranes in single cells and organelles. This article analyses the methodological basis of flux measurements, provides experimental tests, and discusses potential applications. The principle of the method is to equilibrate cells, organelles or vesicles with a fluorescent solute, to deplete the interior of individual cells etc. of fluorescene by the pulse of a high-intensity microbeam, and to monitor influx of solute by microfluorometry. Simple equations are given and a computer curve fitting program is described by which rate constants of influx and membrane permeability coefficients can be derived from fluorescence measurements. The permeability of individual “leaky” human erythrocyte ghosts to fluorescein-isothiocyanate-labelled bovine serum albumin has been measured under various conditions. Multiple exposure to the high-intensity microbeam had no effect on permeability within experimental error. Flux measurements have been also performed on individual vesicles of 1–2 μm radius which had been derived from ghosts. The potential application of the method to sub-lightmicroscopic vesicles and to organelles within living cells is discussed.
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  • 43
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 11 (1984), S. 51-59 
    ISSN: 1432-1017
    Keywords: Nerve ; membrane ; axon ; pressure ; activation volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The absorption of the lipophilic anions dipycrilamine (DPA-) and tetraphenylborate (TPhB-) by the lipid matrix of the squid axon membrane, and the kinetics of their translocation, were studied by the charge pulse relaxation technique. The axons were treated with tetrodotoxin (TTX) and 4-aminopyridine to block the ionic currents responsible for nerve excitation. At high enough concentrations of absorbed ions (∼ 10-12 mol/cm2) the membrane voltage relaxation following a brief current pulse consisted mainly of two exponential components, whose time constants and relative amplitudes were used for estimating the translocation rate constant, K, and the density of absorbed ions, N. These measurements were performed at different hydrostatic pressures in the range 1–100 MPa (∼ 1,000 atm), and at different temperatures in the range 5° C–20° C. Both K and N were found to be little affected by pressure. The pressure dependence of K indicated that the translocation of lipophilic ions across the nerve membrane involves activation volumes of the order of 5 cm3/mol. In all experiments the passive membrane resistance was little affected by pressures up to 80 MPa. However, above 100 MPa it fell dramatically to low values, presumably because of phase separation phenomena between the membrane components. The temperature dependence of K, both for DPa- and TPhB-, implied an activation energy for ion translocation of the order of 60 kJ/mol, close to that measured in artificial lipid bilayers. It is concluded that the lipid bilayer structure of the nerve membrane is not modified by pressures below 80 MPa and that the intramembrane movements of relatively small charged groups cannot account for the large activation volumes involved in the gating of ionic channels.
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  • 44
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 11 (1984), S. 77-77 
    ISSN: 1432-1017
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
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  • 45
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 11 (1984), S. 78-78 
    ISSN: 1432-1017
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
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  • 46
    ISSN: 1432-1017
    Keywords: Oxyhaemoglobin ; resonance Raman scattering ; dispersion of depolarisation ratio ; fifth-order Raman theory ; alkaline Bohr effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The depolarisation ratio and the excitation profiles of some prominent Raman lines of the oxyhaemoglobin spectrum (1,375 cm-1, 1,583 cm-1, 1,638 cm-1) have been measured as functions of the exciting laser frequency. The depolarisation ratio shows a complicated minimum-maximum structure in the preresonant region between Soret- and β-band of the optical spectrum, which depends on the pH-value of the solution. These dispersion curves are interpreted by fifth-order Loudon theory of the polarisability tensor including static distortions of the haem group, which lower its symmetry from the ideal D 4h-symmetry, and enhancement by a second, non-Raman-active phonon. The fitting constants needed to fit the experimental data are related to static distortions of A 1g, B 1g, B 2g, and A 2g` symmetry types and thus give information on the symmetry lowering from D 4h. The variation of the fitting constants with the pH-value of the solution is interpreted to be caused by protonation/deprotonation processes of titrable amino acid groups contributing to the alkaline and acid Bohr effect. The protonation changes the electrostatic interaction energies in the globular protein and destabilises the salt bridge between His(HC3)β and Asp(FG1)β in the R-state. These processes induce distortions of the haem group via haem-apoprotein interactions. Our results give no indication for a dominant role of the covalent Fe2+-N[His(F8)] bond in this process. They are in agreement, however, with the allosteric model of Hopfield, which assumes all interactions to be evenly distributed all over the protein molecule.
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  • 47
    ISSN: 1432-1041
    Keywords: theophylline ; chronopharmacokinetics ; sustained release tablet ; intravenous administration ; absolute bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of time of drug administration on pharmacokinetics of theophylline was studied both after ingestion of a sustained-release tablet, containing choline theophyllinate (Zy 15061-S. R.; Teovent®; Sabidal®; ZYMA S.A.) and after intravenous infusion of aminophylline to eight healthy volunteers. Both drugs were administered in the morning (10 a.m.) and on a separate occasion in the evening (10 p.m.) after a 12 h period of fasting. After oral administration of a dose of 540 mg theophylline, the drug was steadily absorbed, both during day-time and during night-time. In some subjects absorption was slower in the evening. Maximum theophylline plasma concentrations were reached after 3.3±0.4 h (mean±SD) and 3.9±1.4 h respectively (not significantly differentp〉0.05). The maximum plasma concentrations were almost identical after administration in the morning and in the evening (12.6±3.3 mg·l−1 and 13.1±1.4 mg·l−1 respectively). There was also no significant difference (p〉0.05) between the areas under the plasma concentration-time curves after oral and intravenous administration, both at day-time and at night-time. This finding indicates complete bioavailability of the sustained release tablets on both occasions. After administration of the tablets in the morning the plasma concentration 12 h post dosing was significantly lower than after administration in the evening: c 12 1 accounted for 6.0±2.0 mg·l−1 after intake at 10 a.m. and for 7.9±2.1 mg·l−1 after ingestion at 10 p.m. (p〈0.01). A similar observation was done after intravenous administration of the drug: c12 was 6.6±1.6 mg·l−1 after starting the infusion in the morning and 8.0±1.8 mg·l−1 after infusing the drug in the evening (p〈0.01). This phenomenon could be explained by the finding of a significantly prolonged half-life of theophylline during night-time, provided that the plasma concentrations were in the range of 5 to 15 mg·l−1 (which coincides approximately with the therapeutic range of the drug). For day-time elimination the half-life of theophylline was found to be 6.2±0.9 h and for night-time elimination 8.0±2.0 h (p〈0.01), which means an increase of 29.6±20.9% during the night. The prolonged half-life of theophylline at night-time might be of therapeutic benefit in preventing bronchus obstruction in the morning.
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  • 48
    ISSN: 1432-1041
    Keywords: amitriptyline ; kidney function ; uraemics ; biotransformation ; chronic renal failure ; urinary metabolites ; man ; depression ; nortryptyline ; hydroxymetabolites ; unconjugated metabolites ; clinical efficacy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The metabolism of amitriptyline (AMT) has been studied in two groups of depressed in-patients on long term AMT therapy: 11 patients with no other major disease and 8 patients with chronic renal failure, who were being dialysed. The patients with renal insufficiency had decreased concentrations of AMT, nortriptyline (NT) and their unconjugated hydroxymetabolites compared to patients with normal kidney function. The plasma levels of conjugated products were extremely high in the uraemics. The latter metabolites are probably inert. The reduced concentration of unconjugated hydroxymetabolites, which are active compounds, may decrease the clinical effectiveness of the drug.
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  • 49
    ISSN: 1432-1041
    Keywords: diazepam ; metoprolol ; drug combination ; pharmacodynamics ; pharmacokinetics ; drug metabolism ; sedation ; interaction study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 6 normotensive, healthy male volunteers the pharmacodynamic responses (blood pressure, heart rate; sedation index, tracking test, reaction time) to metoprolol (100 mg bid orally), diazepam (0.1 mg/kg intravenously) and to their combination were studied. The pharmacokinetics of diazepam were also compared in a cross-over experiment, with and without pretreatment by the β-adrenoceptor antagonist to evaluate the possibility of a drug interaction. The pharmacodynamic and pharmacokinetic investigations indicated that metoprolol only slightly impaired the elimination of diazepam (18% decrease in total clearance, 25% increase in elimination half-life). The pharmacodynamics of metoprolol (17% decrease in heart rate, 17% decrease in diastolic RR) was not significantly altered by the bolus injection of diazepam. The extent of prolongation in choice reaction time (RT2) induced by diazepam was significantly (p=0.001) more pronounced following the co-administration of metoprolol. However, the results of RT1, the tracking test and the sedation index did not indicate any increased effect due to the β-blocking agent. It is concluded that concomitant treatment with metoprolol and diazepam causes only minor and clinically irrelevant changes in drug metabolism and drug response.
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  • 50
    ISSN: 1432-1041
    Keywords: morphine ; anesthesiology ; epidural application ; pharmacokinetics ; plasma level ; CSF level
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Cerebrospinal fluid (CSF) and plasma morphine concentrations were determined in 5 patients after epidural administration of 6 mg morphine; plasma samples were collected frequently during the initial 6 h and 6–7 CSF samples were obtained from each patient over a 24 h period. Morphine was analysed using gas chromatography and electron capture detection. Individual morphine concentration-time curves were plotted for plasma and CSF and various pharmacokinetic variables were calculated. Plasma morphine concentrations after epidural injection were similar to those found after intramuscular administration; Cmax (66±8 mg/ml: mean±SEM) appeared within 12±3 min, and the terminal elimination half-life in plasma was 213±24 min. In CSF, morphine reached a peak (1575±359 ng/ml) after 135±40 min. The terminal elimination half-life for morphine in CSF was 239±10 min. The CSF bioavailability of morphine after epidural administration was calculated to be 1.9±0.5%. The study showed that epidural administration of morphine resulted in CSF concentrations many times higher than those in plasma, but still only 2% of the dose administered was available to the CSF compartment. Morphine was eliminated with similar speed from CSF and plasma.
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  • 51
    ISSN: 1432-1041
    Keywords: dihydroergotamine ; venoconstriction ; 8′ hydroxy-dihydroergotamine ; main metabolite in man ; time course
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The time course of the venoconstrictor effect of dihydroergotamine and its main metabolite 8′ hydroxy-dihydroergotamine was investigated in a placebo-controlled study in seven healthy male volunteers, after direct local infusion of 0.08 and 0.4 µg into superficial hand veins. Both dihydroergotamine and 8′ hydroxy-dihydroergotamine elicited a similar, marked venoconstrictor effect. The time course of the venoconstrictor action was similar for both compounds; about one third of the effect was present at the end of the infusion, which lasted for 10 min, and it took about a further 20 min for the effect to reach its maximum. The effect then remained fairly constant for the rest of the period of observation of 180 min from the start of the infusion. The data indicate that the pharmacological activity of oral dihydroergotamine is due not only to the unchanged drug but also to its main metabolite, 8′ hydroxy-dihydroergotamine, which occurs in plasma in concentrations about 5–7 times higher than those of dihydroergotamine itself. The absolute bioavailability of unchanged dihydroergotamine, therefore, does not reflect the markedly higher bioavailability of pharmacologically active drug.
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  • 52
    ISSN: 1432-1041
    Keywords: drug absorption ; statistical moments method ; vanishing exponential ; indistinguishable macroconstants ; Wagner-Nelson method ; Lood-Riegelman method ; first order absorption kinetic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Quantitative assessment of drug absorption remains a difficult task, because the multiple-compartment disposition of a drug may not be obvious after oral administration (the problem of the vanishing exponential) and the macroconstants are indistinguishable. For these reasons, proper analysis of the drug absorption based on the apparent behavior of oral data without intravenous reference curve rarely provides absorption information useful for in vivo — in vitro correlations. When intravenous reference curve is available, compartment model used for analysis of the oral data should be corresponding to the iv data such as the Loo-Riegelman method. The model independent statistical moments method is one of the preferable alternatives because of its ease of computation and its potentially smaller error, if absorption can be assumed to be first-order.
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  • 53
    ISSN: 1432-1041
    Keywords: propranolol ; plasma protein binding ; age effects ; α1-acid glycoprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The extent of propranolol protein binding was determined in three different age groups of healthy drug-free caucasian males. Volunteers selected for study were 6–15 years old, 25–36 years old and 68–76 years old. Ten milliliters of blood were obtained via venipuncture and collected in glass tubes from the subjects after an overnight fast. Binding determinations were performed by equilibrium dialysis using radiolabelled propranolol. Serum albumin and α1-acid glycoprotein concentrations were determined in all subjects by radial immunodiffusion. The results obtained showed wide intersubject variability in the binding ratio of propranolol and serum concentrations of α1-acid glycoprotein. Mean albumin serum concentration was found to be significantly lower in the elderly group as compared to the adult and pediatric groups (p〈0.02). A positive correlation was found between the binding ratio of propranolol and the serum concentration of α1-acid glycoprotein in all the subjects (r=+0.66,p〈0.005). No significant correlation was found between the binding ratio of propranolol and the serum concentration of albumin (r=−0.03,p〈0.88). These data suggest that the extent of propranolol binding is influenced primarily by serum concentrations of α1-acid glycoprotein and not by differences in age.
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  • 54
    ISSN: 1432-1041
    Keywords: piretanide ; furosemide ; renal insufficiency ; loop diuretic ; natriuresis ; pharmacokinetics ; diuretic effect ; kaliuresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The natriuretic effect of the new loop diuretic piretanide was investigated in patients with severe renal insufficiency and was compared with that of furosemide. In the first study 4 hospitalized patients (serum creatinine 407 to 1220 µmol/l) were examined after administration of piretanide (12, 24, 48 and 96 mg to two patients, and 24, 48, 96 and 192 mg to 2 other subjects, given every third day). In the second study 6 hospitalized patients (serum creatinine 194 to 698 µmol/l) were studied after receiving orally 2 different doses of piretanide and 2 different doses of furosemide orally, given every fourth day. The mean natriuretic effect of 48 mg and 96 mg piretanide was 250 and 340% of the control value for the entire group, and 311 to 480% in the subgroup of patients with serum creatinine below 530 µmol/l. For a given dose the natriuresis was inversely correlated with renal function, and at a given serum creatinine level the natriuretic response was dose-dependent. The drug had less effect on water and potassium diuresis than on natriuresis. No significant difference in natriuretic effect was found on comparison with furosemide given in the ratio furosemide: piretanide 3.33:1. The pharmacokinetic data showed a direct correlation between the dose and the mean plasma concentration and also between urinary recovery of the drug and the measured natriuretic response.
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  • 55
    ISSN: 1432-1041
    Keywords: gastric acid secretion ; loxtidine ; H2-receptor antagonist ; pepsin secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The gastric inhibitory effects of loxtidine, a new histamine H2-receptor antagonist, were studied in healthy volunteers. Doses of 20, 40 and 80 mg given in the evening reduced nocturnal acid secretion by 91, 97 and 95%, respectively, and nocturnal pepsin secretion by 86, 89 and 90%, respectively. The same doses also increased median 24-hour intragastric pH from 1.6 to 4.1, 5.4 and 5.5, respectively, but intragastric pH had returned to control values by the end of the 24-hour study period. Loxtidine at a dose of 40 mg twice daily rendered gastric contents virtually anacid throughout the 24-hour study period. The powerful gastric inhibitory effects of loxtidine denote a potential use in the treatment of peptic diseases.
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  • 56
    ISSN: 1432-1041
    Keywords: alpha2-adrenoceptors ; phaeochromocytoma ; catecholamines ; adrenoceptor regulation ; platelet alpha2-receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a 44 year-old male with a surgically proven phaeochromocytoma platelet α2-adrenoceptor density, determined by3H-yohimbine binding, was only 50% of that in an age-matched control group, and plasma catecholamines were elevated. Two weeks after removal of the tumour, platelet α2-adrenoceptor density and plasma catecholamines had become normal and were not significantly different from the controls. It is concluded that endogenous catecholamines may play an important role in regulation of α2-adrenoceptor density and hence tissue sensitivity to α-adrenergic stimulation in the human being.
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  • 57
    ISSN: 1432-1041
    Keywords: cyclophosphamide ; cytostatic drug ; cancer therapy ; female breast cancer ; bioavailability ; rapid release formulations ; gastric juice resistant formulation ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Cyclophosphamide (CP) is an alkylating cytostatic compound, which is activated to its cytotoxic form in the liver [1]. Since the therapeutic range of CP in the treatment of human tumours, is small like other cytostatics, a constant high bioavailability is essential for its oral administration. Although CP has become one of the most widely used cytostatics [2], there do not appear to have been any bioavailability investigations providing the necessary information. The development of a very sensitive gas chromatographic analytical method has now permited investigation of the pharmacokinetics of oral CP in conventional clinical doses [3, 4, 5, 6].
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  • 58
    ISSN: 1432-1041
    Keywords: cimetidine ; prednisolone ; aluminium phosphate ; antacids ; bioavailability ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Ten fasting subjects received 200 mg cimetidine orally either with water or 11 g aluminium phosphate mixture in a randomized, single dose, two-way cross-over study. Blood samples were taken for 12 h and urine was collected for 24 h. Cimetidine in plasma and urine was analysed by HPLC. There were no significant differences between the treatments with respect to peak plasma concentration, time to peak plasma concentration, area under the plasma concentration-time curve, and urinary excretion. In 12 healthy subjects the absorption of prednisolone was investigated when given alone and together with 11 g aluminium phosphate. Blood samples were taken over 16 h and prednisolone in plasma was analysed by HPLC. There were no significant differences in the values of area under curve (AUC), Cmax and tmax. The results indicate that aluminium phosphate does not reduce the bioavailability of cimetidine and prednisolone.
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  • 59
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-1041
    Keywords: publication practice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
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  • 60
    ISSN: 1432-1041
    Keywords: sulphapyridine ; sulphasalazine ; pharmacokinetics ; rectal administration ; oral administration ; plasma levels ; ulcerative colitis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Rectal administration of sulphasalazine to patients with ulcerative colitis has recently been shown to have similar therapeutic activity but fewer side effects than oral treatment. The present study is a comparison of the pharmacokinetics of sulphasalazine (SASP) and its metabolite sulphapyridine (SP) after rectal and oral administration of SASP to 6 patients with ulcerative colitis. The areas under the concentration-time curves (AUC) and the maximum concentrations (Cmax) of SASP and SP were significantly lower after rectal than oral administration of SASP (p〈0.05). These findings support the view that the lower frequency of side effects after rectal administration of SASP may result from the lower plasma levels of SASP and SP.
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  • 61
    ISSN: 1432-1041
    Keywords: guar gum ; drug absorption ; dietary fibre ; digoxin ; penicillin ; serum concentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of guar gum on the absorption of digoxin and phenoxymethyl penicillin was studied in a double blind study in 10 healthy volunteers. Guar gum reduced serum digoxin concentration during the early absorption period, but a similar amount of digoxin was found in 24 h urine whether given with or without guar gum. Both the peak penicillin concentration and the area under the serum curve were significantly reduced by the gum.
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  • 62
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-1041
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
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  • 63
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-1041
    Keywords: clinical pharmacology ; pharmaceutical industry ; drug development ; acceleration of clinical assessment ; qualification of clinical effects ; accuracy of drug monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
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  • 64
    ISSN: 1432-1041
    Keywords: clonidine ; hypertension ; therapeutic window ; steady state concentration ; pharmacokinetics