Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1615-6102
    Keywords: Chloroplast division ; Unicellular red alga ; Cyanidium caldarium ; DNA content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The behavior and DNA content of the cell and chloroplast nuclei (synonymous with nucleoids; ct-nuclei) during the life cycle have been studied in a synchronized population of cells of the unicellular algaCyanidium caldarium M-8. Cells were examined by epifluorescence microscopy after staining with 4′,6-diamidino-2-phenylindole (DAPI), and by fluorimetry using a video-intensified microscope photon-counting system (VIMPICS). The young cell contains a single petal-like chloroplast, a spherical cell nucleus and several mitochondria, and the cell nucleus and the chloroplast divide in that order just prior to cytokinesis. The chloroplast contains a ring-shaped ct-nucleus which is located at the periphery of the chloroplast during the life cycle. During the first 40 h after the initiation of sychronous cultures, the young cell and its chloroplast increase markedly in size, and the DNA contents per cell nucleus and per ct-nucleus increase approximately two times and 16 times the value in 16-endospore cells, respectively. Four endospore divisions then occur, at intervals of approximately 12 h between 40 h and 90 h, after the initiation of synchronous cultures. The volume of each cell, the volume of each chloroplast, the amount of chloroplast DNA (ct-DNA), and the level of pigmented material in the chloroplast are reduced stepwise after each endospore division until finally, at the 16-endospore stage, they reach approximately 1/16 of the original values for the mother cell. The size of the mitotic spindle also is reduced stepwise as the cell divisions proceed. By contrast, the cell nuclei duplicate their DNA during each endospore division cycle. These results and analysis of other components indicate that the chloroplasts divide into two daughter chloroplasts without any DNA synthesis during four successive cycles of endospore division and also that the DNA content of the chloroplast is intimately related to the volume of the chloroplast and the cell and to the level of pigmented material in the cloroplast, but is not related to the DNA content of the cell nuclei.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  We investigated the effect of culture temperature on the maximum specific growth rate and the cellular sugar accumulation, and the effect of a temperature shift on the sugar accumulation of Chlorella pyrenoidosa cells in a batch culture system. Increase in temperature below 30 °C appeared to correlate with increase in the maximum specific growth rate, on the contrary the cellular sugar content showed a reverse tendency against temperature. We attempted to utilize this tendency for improving sugar productivity in Chlorella. First, we cultured Chlorella at 28 °C during the logarithmic growth phase to obtain a high specific growth rate. The culture temperature was then shifted from 28 °C to 22 °C at the late logarithmic growth phase in order to reduce the specific growth rate and enhance the cellular sugar accumulation. As a result, we obtained a 15% increase in sugar production over that obtained by cultivation at 28 °C throughout the culture. We also investigated the effect of light-dark time cycle on the sugar productivity and found that this operating variable did not affect the cellular sugar content but influenced the final cell concentration. Among the examined light-dark time cycles, maximum sugar productivity was obtained in the case of 12 h light and 12 h dark period.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fullerenes ; Octadecylsilicas ; Temperature effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of column temperature, especially at low temperatures, on the separation of fullerenes on monomeric and polymeric octadecyl silica (ODS) bonded phases has been studied. Decreasing the column temperature induces an increase in selectivity. The best temperature for the separation of fullerenes was determined for both types of ODS phase with n-hexane eluent. The selectivity for higher fullerenes on monomeric phases becomes similar to that on polymeric phases to low temperature. It has been found that as the carbon content of monomeric phases is increased, the selectivity also becomes similar to polymeric phases.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1437-2320
    Keywords: Key words Aneurysm ⋅ Anomalies ⋅ Basilar artery ⋅ Endovascular therapy ⋅ Embolization ⋅ Interventional neuroradiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Basilar trunk saccular aneurysms associated with fenestration are infrequent, especially in the middle or distal portion of the basilar artery. Surgical treatment of the basilar trunk aneurysm is difficult, due to its anatomical environment and the complicated surgical exposure. A 46-year-old woman presenting with Hunt and Kosnik grade II subarachnoid hemorrhage was found to have a ruptured aneurysm arising at the proximal corner of the associated fenestration in the middle portion of the basilar artery. Because of surgical difficulties anticipated in approaching the aneurysm, it was decided to treat it with endovascular embolization utilizing the Guglielmi detachable coil; and complete occlusion of the aneurysm was obtained. The efficacy of endovascular treatment for the basilar trunk aneurysm with associated fenestration is discussed from anatomical and embryological points of view, and relevant literature is reviewed.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1573-6903
    Keywords: [3H]acetylcholine release ; cerebral cortex ; 4-aminopyridine ; 1,1-dimethyl-3-(4-amino-3-pyridyl) ; SDAT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The release of acetylcholine (ACh) elicited by electrical stimulation was investigated in rat brain cortical slices preloaded with3H-choline. Decreasing the [Ca2+]o from 2.5 to 0.3 mM caused a progressive reduction of the evoked release of ACh. 4-Aminopyridine (4AP) or LF14 [(1,1-dimethyl-3-(4-amino-3-pyridyl)], 4×10−5 M doubled the evoked release of ACh when the [Ca2+]o was 2.5 mM and quadrupled it when it was 0.3 mM, to levels higher than those obtained with 2.5 mM [Ca2+]o alone. This indicates that both 4AP and LF14 decrease the Ca2+ requirements for the evoked release of ACh. The findings of this study indicate that LF14 may be suitable for the symptomatic treatment of senile dementia of Alzheimer's type, presumably caused by dysfuntion of cholinergic transmission in the brain.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fullerenes ; On-line and off-line identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of fullerenes with a monomeric octadecylsilica bonded phase using n-hexane or toluene/methanol mobile phase systems is described. Analytical and preparative separations, incorporating on-line UV/VIS spectral measurements, confirmed the existence of large fullerenes such as C76, C78 and C84. However, isomers of C78 and C84 were not conclusively found.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Molecular recognition ; Multidentate phenyl-bonded phases ; PAHs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary New multidentate phenyl-bonded phases (MPBPs) were synthesized and evaluated the chromatographic retention behaviour with polycyclic aromatic hydrocarbons as sample probes in high-performance liquid chromatography. The new MPBPs show different retention characteristics from the previously synthesized MPBP, designated TP. Nevertheless, the results indicate that the retention mechanism is still the same as the TP phase: the size and shape of the solute molecule can be recognized by a cavity-like space formed by the methyl groups and phenyl rings of MPBPs.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1617-4623
    Keywords: Key words Catalase ; Oryza ; Rice ; Evolution ; Tourist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tourist-OsaCatA, a transposable element, was found in the 5′-flanking region of the rice gene CatA. The characteristics of this element are similar to those of the other Tourist elements so far found in Oryza sativa. PCR and sequence analyses of 37 accessions of 18 species revealed that all the Oryza species examined, except for one accession, have either a full-length or a partial Tourist element at this locus. Unlike the Tourist elements previously reported, this Tourist element is found in all four Oryza species complexes in the Oryzeae tribe. All AA genome Oryza species, except O. longistaminata, contain the full-length Tourist element. O. longistaminata and the species of the O. officinalis, O. meyeriana and O. ridleyi complexes contain the partial element. A phylogenetic tree of Oryza species based on the nucleotide sequences of these Tourist elements was constructed. The O. longistaminata accessions were placed near the neighboring cluster of the officinalis complex. We propose that the ancestor of O. longistaminata and that of other species with the AA genome diverged, and the ancestor(s) of the O. officinalis, O. ridleyi and O. meyeriana complexes then diverged from the ancestor of O. longistaminata in the course of the evolution of the Oryza species. The Tourist elements associated with CatA and its orthologs thus provide useful tools for examining evolutionary relationships among Oryza species.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1432-2242
    Keywords: Key words Catalase ; Oryza ; Rice ; Evolution ; p-SINE1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Intron-2 of the Oryza sativa CatA catalase gene is similar in nucleotide sequence to p-SINE1, a retroposon, and seems to have been added to the ancestral genome of rice. To examine when the p-SINE1-like intron was inserted into CatA during the evolutionary divergence of Oryza species, and to elucidate the evolutionary relationships among Oryza species using the sequence of the intron as a marker, we performed polymerase chain reaction (PCR) analyses of 32 accessions of 17 Oryza species with various genome types. Agarose-gel electrophoresis of the PCR products revealed that all the Oryza species with an AA genome have the CatA homolog with the intron, whereas other Oryza species have the CatA homolog without the intron. These results indicate that intron-2 of CatA is a good marker for distinguishing species with an AA genome among Oryza species. Sequencing of the PCR products showed that all the introns are similar to p-SINE1, though with slight variations in length. We also performed PCR analyses using four accessions of three species in genera related to Oryza, and found that there is an intron in the CatA homolog of Leersia perrieri. On the other hand, the CatA homolog of Porteresia coarctata has no intron. Sequence data showed that the L. perrieri homolog has a p-SINE1-like intron similar to that in Oryza species with an AA genome. These results suggest that the p-SINE1-like intron was already present in the common ancestor of Oryza and L. perrieri and was then lost in the ancestors of P. coarctata and of the Oryza species other than those with an AA genome. The phylogenetic tree of Oryza species with an AA genome based on the nucleotide sequences of the introns leads us to propose that Oryza species with an AA genome evolved from an ancestor of Oryza longistaminata.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...