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  • 1
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The posterior pole cytoplasm of early embryos ofDrosophila melanogaster was irradiated with increasing doses of U.V. light at a wave length specific for nucleic acids 35 and 75 min after ovoposition, when nuclei were still inside the yolk mass. Probit analysis showed that: Sterility was higher in irradiations performed at 35 min. Mortality was higher in the experiment performed at 75 min. After treatment at 35 min, sterility and mortality were independent phenomena. The numbers of targets involved in germ cell determination were of the order of tens and hundreds at 35 and 75 min respectively. The numbers of targets involved in viability were of several orders of magnitude in both developmental stages. The irradiation, even at very low doses, caused a background effect which was probably due to “old” embryos. The sex ratio was distorted in favour of females at high doses and of males at low doses.
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  • 2
    ISSN: 1432-041X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The posterior pole ofDrosophila melanogaster eggs was irradiated with ultraviolet light of 253.7 nm wavelength; different batches were irradiated at different times after oviposition, ranging from less than 10 mins to 125 mins. Two different experiments were run at different dose levels: 280 μW/mm2 and 530 μW/mm2. A differential response to irrariation was observed in relation to the age of the treated eggs. Embryo mortality increased with egg age in both experiments (Fig. 1). No differential effects onlarval mortality were found in egg batches irradiated between 15 and 95 mins of age in either experiment (Fig. 3). The incidence ofsterility in the survivors was higher when the eggs were irradiated before 55 mins or when pole nuclei were present. The overall incidence of sterility was much higher in the high-dose experiment (Fig. 4). Sterility is considered as a measure of damage to germ cell precursors, most probably involving RNA. On this basis the probability of the affected RNA being messenger RNA stored in polar granules is discussed.
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  • 3
    ISSN: 0020-1693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
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  • 4
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract A restriction endonuclease analysis was performed on four strains of Borrelia burgdorferi: one isolated from man (SF), one from Ixodes dammini (B31) and two form I. ricinus (BITS in Italy and B45 in Germany). Digestion by Taq I and Hae III gave the best resolution of the DNA fragments. Three different restriction patterns were obtained: BITS and B45 showed only one band difference. These results correlate with the reactivity of the four strains with monoclonal antibodies.
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  • 5
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Seven strains of Borrelia burgdorferi isolated from ticks and from human beings in Europe and U.S.A. were analyzed for DNA restriction patterns with several enzymes and for DNA homology in Southern blot hybridizations. The restriction patterns showed a moderately high variability. In Southern blot hybridization, strain B31 (U.S.A.) DNA gave a strong signal with itself, strains Bsf (U.S.A.) and Alcaide (isolated in Italy but presumably contracted in Venezuela). Strain B45 (F.R.G.) hybridized to itself, strain BITS (Italy) and to strain D.A. (Italy). Strain Nancy (Italy) gave a signal only when hybridized to itself, although it was classified as Borrelia on the basis of the clinical manifestations, SDS-PAGE protein pattern and antigenic determinants. No hybridization differences were observed for strains isolated from different hosts in the same continental geographical area.
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  • 6
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Rabbits were immunised using 2 mg of purified ox liver glycoprotein isolated in our laboratory as before7. Antigen plus Freund's complete adjuvant was given in five injections into all four legs and the neck. The operation was repeated with Freund's incomplete adjuvant a month later. A secondary ...
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 9 (1976), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A total of 210 samples of haemoglobin of Trachurus trachurus (L.) caught in the Gulf of Trieste in 1972–1973, were analysed in search of haemoglobin polymorphism. Genetic polymorphism may be used as a genetic marker to identify sub–populations on the basis of allele frequencies.All the samples analysed produced the same haemoglobinic pattern, composed of six bands. The quantitative differences noted between the various fractions were not sufficient to demonstrate the existence of different phenotypes.Denaturation tests carried out by treating erythrocytes with non–sterile physiological solutions or by keeping the haemolysate at room temperature before electrophoresis, resulted in new patterns. This result shows the importance of the careful treatment of blood samples to assure reliable results.
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  • 8
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To evaluate the effect of immersion in water on maternal haemodynamic measures and fetal heart rate patterns in healthy nulliparous women.Design A randomised cross-over study.Participants Twenty pregnant women were studied between 26–29 weeks and between 34–37 weeks of gestation.Methods The women were either immersed in water for 35 minutes or rested on a bed for a similar period of time. Maternal blood pressure, thoracic electrical bioimpedance, urine and blood samples, and fetal heart rate patterns were obtained before and after immersion or bedrest.Results Compared with bedrest and pre-immersion values, immersion resulted in a significant decrease in blood pressure, which returned to baseline values within 1.5 hour. Urine production increased for a short period after immersion, but 24 hour samples showed no difference compared with bedrest. Sodium, potassium and creatinine levels in urine remained constant. No significant changes were found for the other haemodynamic measures. There were no effects on fetal heart rate nor on its variation.Conclusion In healthy pregnant women immersion for 35 minutes has a clear effect on blood pressure and urine production. However, these effects are short lasting.
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  • 9
    ISSN: 1432-2242
    Keywords: Key words Coffea arabica ; Introgression ; Genetic diversity ; Alien gene transfer ; AFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Nineteen arabica coffee introgression lines (BC1F4) and two accessions derived from a spontaneous interspecific cross (i.e. Timor Hybrid) between Coffea arabica (2n=4x=44) and C. canephora (2n=2x=22) were analysed for the introgression of C. canephora genetic material. The Timor Hybrid-derived genotypes were evaluated by AFLP, using 42 different primer combinations, and compared to 23 accessions of C. arabica and 8 accessions of C. canephora. A total of 1062 polymorphic fragments were scored among the 52 accessions analysed. One hundred and seventy-eight markers consisting of 109 additional bands (i.e. introgressed markers) and 69 missing bands distinguished the group composed of the Timor Hybrid-derived genotypes from the accessions of C. arabica. AFLP therefore seemed to be an extremely efficient technique for DNA marker generation in coffee as well as for the detection of introgression in C. arabica. The genetic diversity observed in the Timor Hybrid-derived genotypes appeared to be approximately double that in C. arabica. Although representing only a small proportion of the genetic diversity available in C. canephora, the Timor Hybrid obviously constitutes a considerable source of genetic diversity for arabica breeding. Analysis of genetic relationships among the Timor Hybrid-derived genotypes suggested that introgression was not restricted to chromosome substitution but also involved chromosome recombinations. Furthermore, the Timor Hybrid-derived genotypes varied considerably in the number of AFLP markers attributable to introgression. In this way, the introgressed markers identified in the analysed arabica coffee introgressed genotypes were estimated to represent from 9% to 29% of the C. canephora genome. Nevertheless, the amount of alien genetic material in the introgression arabica lines remains substantial and should justify the development of adapted breeding strategies.
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  • 10
    ISSN: 1437-1596
    Keywords: Key words Y chromosome ; Haplotypes ; Evolution ; Population studies ; Genetic affinities ; STR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Notes: Abstract By means of a multicenter study, a large number of males have been characterized for Y-chromosome specific short tandem repeats (STRs) or microsatellites. A complete summary of the allele frequency distributions for these Y-STRs is presented in the Appendix. This manuscript describes in more detail some of the population genetic and evolutionary aspects for a restricted set of seven chromosome Y STRs in a selected number of population samples. For all the chromosome Y STRs markedly different region-specific allele frequency distributions were observed, also when closely related populations were compared. Haplotype analyses using AMOVA showed that when four different European male groups (Germans, Dutch, Swiss, Italians) were compared, less than 10% of the total genetic variability was due to differences between these populations. Nevertheless, these pairwise comparisons revealed significant differences between most population pairs. Assuming a step-wise mutation model and a mutation frequency of 0.21%, it was estimated that chromosome Y STR-based evolutionary lines of descent can be reliably inferred over a time-span of only 1950 generations (or about 49000 years). This reduces the reliability of the inference of population affinities to a historical, rather than evolutionary time scale. This is best illustrated by the construction of a human evolutionary tree based on chromosome Y STRs in which most of the branches connect in a markedly different way compared with trees based on classical protein polymorphisms and/or mtDNA sequence variation. Thus, the chromosome Y STRs seem to be very useful in comparing closely related populations which cannot probably be separated by e.g. autosomal STRs. However, in order to be used in an evolutionary context they need to be combined with more stable Y-polymorphisms e.g. base-substitutions.
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