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141.
Olivier Cohen Christine Cans Jean Louis Gilardi Hubert Roth Marie-Ange Mermet Pierre Jalbert Jacques Demongeot Martine Cuillel 《Human genetics》1996,97(5):659-667
Reciprocal translocations (rcp) are among the most common constitutional chromosomal aberrations in man. Using a European
database of 1574 families carrying autosomal rcp, a cartographic study was done on the breakpoints involved. The breakpoints
are non-randomly distributed along the different chromosomes, indicating “hot spots”. Breakpoints of rcp that result in descendants
that are unbalanced chromosomally at birth are more frequent in a distal position on chromosomal arms, and 65% of them are
localised in R-bands. Among the R-bands, bands rich in GC islands and poor in Alu repetitive sequences are more frequently
the site of breakpoints, as well as bands that include a fragile site. This result suggests that the variation in degree of
methylation in GC islands could be involved in chromosomal breakage and hence in chromosomal rearrangements.
Received: 10 April 1995 / Revised: 1 July 1995 相似文献
142.
Maria de Fatima Bonaldo Pierre Jelenc Long Su Lee Lawton M. -T. Wu Dorothy Warburton Marcelo Bento Soares 《Human genetics》1996,97(4):441-452
A study was conducted on the feasibility of isolating genes and pseudogenes that map to chromosome 13 by a hybridization-based approach using a 13-specific library and pools of repeat-free cDNA clones. Five pairs of cDNA and chromosome 13 genomic clones were identified and characterized. Partial or full-length sequence was derived from all cDNAs, and database searches were performed for putative gene identification. Partial sequence was also obtained from the chromosome 13 genomic clones for comparison with those of the hybridizing cDNAs. As a result of these analyses we identified three genes, a putative homologue of a porcine mRNA encoding an unidentified hepatic protein, a putative homologue of a yeast integral membrane protein, and a gene for a translationally controlled tumor protein, and two processed pseudogenes, ribosomal proteins L23a and S3a. The latter was formerly identified as the v-fos transformation effector gene, Fte-1, and recently cited as a possible candidate for the BRCA2 gene on chromosome 13. All genes and pseudogenes were localized to cytogenetic bands by in situ hybridization of metaphase chromosomes with probes derived from the chromosome 13 genomic clones. 相似文献
143.
We review some of the older literature concerning metabolic turnover of cholesterol in the nervous system. The overall picture
is that incorporation of radioactive precursors into brain cholesterol is roughly proportional to the rate of myelination
and that, once incorporated, radioactive cholesterol is relatively stable metabolically. We outline a strategy for demonstrating
the source (local synthesis or uptake from the circulation) of cholesterol in brain. The experimental design involves determining
the rate of accumulation of cholesterol this is calculated as the increasing amounts of sterol in brain at successive time
intervals during development. The rate of appearance of newly synthesized cholesterol is determined from incorporation of
radioactivity from3H2O (injected i.p. several hours prior to sacrifice) into cholesterol. The radioactivity associated with the sterol fractions
and the specific activity of body water determined from the serum can be used to calculate the absolute amount of sterol newly
synthesized during the time when3H2O was present. The results obtained demonstrated that all of the bulk cholesterol accumulating in brain can be accounted for
by newly synthesized cholesterol. None of the radioactive cholesterol came from the circulation, since cholesterol feeding
suppressed cholesterol biosynthesis in the liver and specific radioactivity of circulating cholesterol was negligible. Thus,
almost all cholesterol accumulating in brain during development is locally synthesized.
Special issue dedicated to Dr. Marion R. Smith. 相似文献
144.
Influence of microtubule-associated proteins on the differential effects of paclitaxel and docetaxel 总被引:1,自引:0,他引:1
Yves Fromes P. Gounon R. Veitia M. C. Bissery A. Fellous 《Journal of Protein Chemistry》1996,15(4):377-388
Microtubules are complex structures arising in part from the polymerization of tubulin dimers. Tubulin binds to a wide range of drugs which have been used as probes for tubulin conformation and assembly properties. There is some evidence that taxol and taxotere have differing effects on tubulin conformation. Previous work has shown that MAP2 and Tau, although they both induce microtubule assembly, have qualitatively different effects on tubulin's behavior. Since most microtubulesin vivo are likely to be associated with MAPs, we decided to characterize the differential effects of MAP2, Tau, taxol, and taxotere on tubulin polymerization with the aim of understanding the mechanisms through which these agents stimulate microtubule assembly. Furthermore, the inhibitive effect of calcium has been used to elucidate the ability of the two drugs to force tubulin assembly. These observations suggest that docetaxel, in addition to its greater efficiency in tubulin assembly, may have the capacity to differently alter certain classes of microtubules. Tau and MAP2 accessory proteins may represent important cofactors modulating the effects of taxoids. 相似文献
145.
Josiane Arnaud Pierre Bourlard Bernard Denis Alain E. Favier 《Biological trace element research》1996,53(1-3):129-136
This study was carried out to assess manganese (Mn) status after an acute episode of myocardial infarction. Plasma and erythrocyte
Mn concentrations were measured from admission to hospital to day 15 postadmission in 21 patients suffering from acute myocardial
infarction and in three control groups. The determination of Mn in these biological fluids was performed by electrothermal
atomic absorption spectrometry. Plasma Mn was higher (p<0.01) and erythrocyte Mn was similar in the acute myocardial infarction group compared to healthy age-matched control group.
Plasma and erythrocyte Mn remained unchanged during the 2 wk after acute myocardial infarction and were not correlated to
enzyme activities. A decrease of erythrocyte Mn with age, expressed in nmol/L, was noted (p<0.02). These results suggest that plasma and erythrocyte Mn do not provide an indication of myocardial damage. Nonetheless,
Mn status in elderly merits further attention. 相似文献
146.
The genusLepidauchen is discussed and defined. It is removed from the family Lepocreadiidae and placed in the family Acanthocolpidae based mainly on its possession of a uterine seminal receptacle. The type, and only valid species,L. stenostoma, is redescribed using material fromLabrus merula from Corsica. Material fromCoris julis andSymphodus tinca from the western Mediterranean off Marseille,L. merula from the western Mediterranean off Valencia,Diplodus annularis andLithognathus mormyrus from the Adriatic Sea off Montenegro, andArchosargus unimaculatus from Venezuela was also examined. Other nominal species are discussed, but none are considered valid within this genus. 相似文献
147.
Spectral and kinetic characteristics of fluorescence from isolated reaction centers of photosynthetic purple bacteria Rhodobacter sphaeroides and Rhodobacter capsulatus were measured at room temperature under rectangular shape of excitation at 810 nm. The kinetics of fluorescence at 915 nm reflected redox changes due to light and dark reactions in the donor and acceptor quinone complex of the reaction center as identified by absorption changes at 865 nm (bacteriochlorophyll dimer) and 450 nm (quinones) measured simultaneously with the fluorescence. Based on redox titration and gradual bleaching of the dimer, the yield of fluorescence from reaction centers could be separated into a time-dependent (originating from the dimer) and a constant part (coming from contaminating pigment (detached bacteriochlorin)). The origin was also confirmed by the corresponding excitation spectra of the 915 nm fluorescence. The ratio of yields of constant fluorescence over variable fluorescence was much smaller in Rhodobacter sphaeroides (0.15±0.1) than in Rhodobacter capsulatus (1.2±0.3). It was shown that the changes in fluorescence yield reflected the disappearance of the dimer and the quenching by the oxidized primary quinone. The redox changes of the secondary quinone did not have any influence on the yield but excess quinone in the solution quenched the (constant part of) fluorescence. The relative yields of fluorescence in different redox states of the reaction center were tabulated. The fluorescence of the dimer can be used as an effective tool in studies of redox reactions in reaction centers, an alternative to the measurements of absorption kinetics.Abbreviations Bchl
bacteriochlorophyll
- Bpheo
bacteriopheophytin
- D
electron donor to P+
- P
bacteriochlorophyll dimer
- Q
quinone acceptor
- QA
primary quinone acceptor
- QB
secondary quinone acceptor
- RC
reaction center protein
- UQ6
ubiquinone-30 相似文献
148.
Molecular cloning of the lectin and a lectin-related protein from common Solomon's seal (Polygonatum multiflorum) 总被引:3,自引:0,他引:3
Els J. M. Van Damme Annick Barre Pierre Rougé Fred Van Leuven Jan Balzarini Willy J. Peumans 《Plant molecular biology》1996,31(3):657-672
The most prominent protein ofPolygonatum multiflorum (common Solomon's seal) rhizomes has been identified as a mannose-binding lectin. Analysis of the purified lectin demonstrated that it is a tetramer of four identical subunits of 14 kDa. Molecular cloning further revealed that the lectin from this typical Liliaceae species belongs to the superfamily of monocot mannose-binding proteins. Screening of cDNA libraries constructed with RNA isolated from buds, leaves and flowers ofP. multiflorum also yielded cDNA clones encoding a protein, which contains two tandemly arranged domains with an obvious sequence homology to the mannose-binding lectins. Molecular modelling of thePolygonatum lectin and lectin-related protein indicated that the three-dimensional structure of both proteins strongly resembles that of the snowdrop lectin. In addition, this approach suggested that the presumed carbohydrate-binding sites of the lectin can accommodate a mannose residue whereas most of the carbohydratebinding sites of the lectin-related protein cannot.Abbreviations GNA
Galanthus nivalis agglutinin
- HCA
hydrophobic cluster analysis
- LECPMA
cDNA clone encoding PMA
- PM30
30 kDa protein isolated fromPolygonatum multiforum
- PMA
Polygonatum multiflorum agglutinin
- PMLRP
Polygonatum multiflorum lectin-related protein 相似文献
149.
150.
The lactic yeast Kluyveromyces marxianus var.marxianus (formerly K. fragilis) autolyzates at faster rate than Saccharomyces cerevisiae. During K. marxianus autolysis, quite similar release kinetics were observed for intracellular space markers (potassium ions, nucleotides), cell-wall components (polysaccharides, N-acetyl-D-Glucosamine) and non specific products (amino nitrogen). By Scanning Electronic Microscopy examination, no cell burst was observed, but a variation in cell shape (from ellipsoidal to cylindrical), as well as a 43% decrease in the internal volume were observed. The mechanism proposed for S. cerevisiae autolysis appeared also likely for K. marxianus.Abbreviations NacGlc
N-acetyl-D-glucosamine
- x
total biomass (dry cellular weight) concentration 相似文献