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排序方式: 共有835条查询结果,搜索用时 31 毫秒
1.
Saccharomyces cerevisiae CDC8 gene and its product. 总被引:14,自引:6,他引:8
2.
3.
J L Valatx L Paut-Pagano M Fevre-Montange J B Dumas Milne Edwards M Jouvet 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1992,315(7):295-301
By means of immunocytochemistry, a central neuronal network containing a prolactin-like substance has been described in the rat. In order to demonstrate the synthesis of this peptide in these cells, we examined the presence of prolactin messenger RNA (PRL mRNA) in several brain samples including the pituitary gland. Amplification of the PRL mRNA was performed by the polymerase chain reaction technique, followed by southern blotting and hybridization with a specific oligonucleotide. Results showed the presence of the expected cDNA (468 bp) in the hypothalamus. Another cDNA with a lower molecular weight was also observed. 相似文献
4.
The quality of Cucurbita pepo L. pollen was studied using field pollinations and the fluorochromatic-reaction test. The extreme sensitivity of this pollen to dehydration and ageing is demonstrated. Controlled stress applied to mature pollen leads to the development of seedless fruits. Molecular signals seem to be involved in the induction of this parthenocarpy. These results indicate the existence of distinct sequences involved in the completion of the fertilization program of pollen. With pollen altered by stress, the fertilization process may be stopped at different stages of its completion. We bring evidence that Cucurbita pepo plants have developed special adaptations in order to compensate for the poor viability of their pollen.Abbreviation FCR
fluorochromatic reaction 相似文献
5.
The posterior ligaments: ligamentum flavum, articular, interspinous and supraspinous ligaments of twenty five fresh cadaveric intervertebral segments, from T11-T12 to L4-L5, extracted from fourteen spines were tested in tension. A progressive dissection method was used, that is, each segment was tested after first resecting the disk with the ligaments intact and a force-elongation curve obtained. Then one ligament was cut and the test repeated, and so on. The most restrictive ligament was found to be the ligamentum flavum followed by the articular, interspinous, and supraspinous ligaments. 相似文献
6.
Catherine Digonnet-Kerhoas Gilles Gay Jean Claude Duplan Christian Dumas 《Planta》1989,179(2):165-170
During ageing of the short-lived pollen grains of Cucurbita pepo L., water loss was examined in relation to viability using biophysical (1H-nuclear magnetic resonance, NMR) and cytological methods (fluorochromatic reaction test, freezefracture and scanning electron microscopy). A semi-logarithmic representation of the pollen weight loss demonstrated the complexity of the dehydration process. A the study of proton loss using 1H-NMR indicated that two major releases water of had taken place, each with different flux rates. Pulse 1H-NMR experiments showed the occurrene of non-exponential signal decay as a function of time, indicating the existence of different fractions of water in a pollen grain sample. These fractions leave the pollen grain at different times during pollen dehydration, and one of them (that of the so-called vital water) can be related to pollen viability. The quantity of protons giving a signal during pulse 1H-NMR experiments was very low when the pollen grains were judged to be dead according to the fluorochromatic test. Freeze-fracture replicas of these dead pollen grains (less than 25% water content) showed that the plasma membrane had become detached from the intine surface; this ultrastructural feature might therefore be involved in the loss of pollen viability.Abbreviations A
initial amplitude of the NMR signal
- A2
quantity of water charcterized by T2-2
- A5
quantity of water characterized by T2–5
- FCR
fluorochromatic reaction
- NMR
nuclear magnetic resonance
- T2
transverse relaxation time
- T2-2
T2 measured with 2 ms between each pulse of radiofrequency
- T2–5
T2 measured with 5 ms between each pulse of radiofrequency 相似文献
7.
The alpha-like globin gene cluster in rabbits contains embryonic zeta-
globin genes, an adult alpha-globin gene, and theta-globin genes of
undetermined function. The basic arrangement of genes, deduced from
analysis of cloned DNA fragments, is 5'-zeta 0-zeta 1-alpha 1-theta 1- zeta
2-zeta 3-theta 2-3'. However, the pattern of restriction fragments
containing zeta- and theta-globin genes varies among individual rabbits.
Analysis of BamHI fragments of genomic DNA from 24 New Zealand white
rabbits revealed eight different patterns of fragments containing
zeta-globin genes. The large BamHI fragments containing genes zeta 0 and
zeta 1 are polymorphic in length, whereas a 1.9-kb fragment containing the
zeta 2 gene and the 3.5-kb fragment containing the zeta 3 gene do not vary
in size. In contrast to this constancy in the size of the restriction
fragments, the copy number of the zeta 2 and zeta 3 genes does vary among
different rabbits. No length polymorphism was detected in the BamHI
fragments containing the theta-globin genes, but again the copy number
varies for restriction fragments containing the theta 2 gene. The alpha 1-
and theta 1-globin genes are located in a nonpolymorphic 7.2-kb BamHI
fragment. The combined data from hybridization with both zeta and theta
probes shows that the BamHI cleavage pattern does not vary within the
region 5'-alpha 1-theta 1- zeta 2-zeta 3-theta 2-3', but the pattern
genomic blot-hybridization patterns for the progeny of parental rabbits
with different zeta-globin gene patterns shows that the polymorphic
patterns are inherited in a Mendelian fashion. Two different haplotypes
have been mapped based on the genomic blot-hybridization data. The
variation in the alpha-like globin gene cluster in the rabbit population
results both from differences in the copy number of the duplication block
containing the zeta-zeta-theta gene set and from the presence or absence of
polymorphic BamHI sites.
相似文献
8.
Intercellular fluid (IF) extracted from the apoplastic leaf spaces of Petunia contained up to 6 new soluble proteins, called d proteins (d0 to d5). Characterisation of the d proteins has shown that they can be divided into groups and show a genetic variability similar to the PR(b) proteins from Nicotiana. d protein patterns from Petunia interspecific hybrids clearly show that the determinant for the d proteins in sexually transmitted as is the case for b proteins in Nicotiana. d-protein induction in TMV-SM1 infected Petunia leaves is discussed in relation to the resistance to infection shown by cultivars and hybrids of Petunia. 相似文献
9.
Summary An attempt was made to transfer two sorts of DNA into maize via pollen grains. Controls for both pollen quality and DNA behaviour during the transformation experiments were included. When genomic DNA was used, no transformants were observed among the 1805 seeds screened. With plasmid DNA (harbouring the gene expressing kanamycin resistance in plant cells), three plants with kanamycin resistance were observed among the 1723 seeds screened, although no molecular evidence of transformation was obtained. Experiments indicated that under the conditions used, DNA was being degraded by both pollen and stigma nucleases. Consequently, we attempted to determine protocols which would inhibit these nuclease activities in order to preserve DNA integrity during transformation experiments, thus allowing fertilization. We found that a classic germination medium supplemented by 300 or 600 mM KNO3, or 20% PEG1550 satisfied all these conditions.Abbreviations BK
Brewbaker and Kwack medium
- BKS15
Brewbaker and Kwack medium containing 15% (w/v) sucrose
- EDTA
ethyldiaminetetraacetic acid
- FCR
fluorochromatic reaction
- FP
fertilization percentage
- PEG
polyethylene-glycol 相似文献
10.
Trimethyloxonium modification of single batrachotoxin-activated sodium channels in planar bilayers. Changes in unit conductance and in block by saxitoxin and calcium 总被引:13,自引:9,他引:4
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Single batrachotoxin-activated sodium channels from rat brain were modified by trimethyloxonium (TMO) after incorporation in planar lipid bilayers. TMO modification eliminated saxitoxin (STX) sensitivity, reduced the single channel conductance by 37%, and reduced calcium block of inward sodium currents. These effects always occurred concomitantly, in an all-or-none fashion. Calcium and STX protected sodium channels from TMO modification with potencies similar to their affinities for block. Calcium inhibited STX binding to rat brain membrane vesicles and relieved toxin block of channels in bilayers, apparently by competing with STX for the toxin binding site. These results suggest that toxins, permeant cations, and blocking cations can interact with a common site on the sodium channel near the extracellular surface. It is likely that permeant cations transiently bind to this superficial site, as the first of several steps in passing inward through the channel. 相似文献