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261.
262.
Kazuhiro Nakaya 《Ichthyological Research》1988,34(4):431-442
Data on the individual variation and changes with growth in proportions and morphology are presented for the poorly known Apristurus longicephalus, and compared with those of other species. A. longicephalus is concluded to be a distinct species without synonyms, characterized by its long snout, widely separate nostrils, long caudal fin, short abdomen, very sparse teeth, and low number of monospondylous vertebrae. It is a species of small size, maturing at about 42 cm in total length. 相似文献
263.
Scale morphology, growth and the squarnation chronology are described for the hermaphroditic fish Rivulus marmoratus reared in the laboratory. The scales are round or oval shaped cycloid type, and their sizes are about 0.3–1.0 mm in diameter. The number of ridges increases more rapidly relative to the body growth of the fish in early stages, but this increase is proportionate to growth subsequently. Three loci of scale development have been identified. The scales first appeared on the center of the parietal region at 8 days after hatching. The second locus of scale formation was on the lateral line of the posterior end of the caudal peduncle. A third locus was later observed on the lower right corner of the operculum: The final squamation was completed at 6 weeks after hatching. 相似文献
264.
A comprehensive classification of nucleic acid structural families based on strand direction and base pairing.
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We propose a classification of DNA structures formed from 1 to 4 strands, based only on relative strand directions, base to strand orientation and base pairing geometries. This classification and its associated notation enable all nucleic acids to be grouped into structural families and bring to light possible structures which have not yet been observed experimentally. It also helps in understanding transitions between families and can assist in the design of multistrand structures. 相似文献
265.
Rhida M'Rad Marek Sanak Georges Deschenes Jing Zhou Catherine Bonaiti-Pellie Laurent Holvoet-Vermaut Solange Heuertz Marie-Claire Gubler Michel Broyer Jean-Pierre Grunfeld Karl Tryggvason Marie-Claude Hors-Cayla 《Human genetics》1992,90(4):420-426
Thirty one families with Alport syndrome including 3 families with associated syndromes were studied. The location of the COL4A5 gene, responsible for the Alport syndrome, was determined by linkage analysis with eight probes of the Xq arm and by a radiation hybrid panel. Concordant data indicated the localization of the Alport gene between DXS17 and DXS11. Four deletions and one single base mutation of the COL4A5 gene were detected. Homogeneity tests failed to show any evidence of genetic heterogeneity superimposed on clinical heterogeneity for ophthalmic signs and end-stage renal disease age. 相似文献
266.
By means of technique of cell culture, 3H-thymidine incorporation and dot blot, it was demonstrated that angiotensin II (AGT II) stimulated proliferation and c-fos oncogene expression in cultured SHR vascular smooth muscle cells (VSMC) in a dose-dependent manner. This effect of AGT II was significantly inhibited by co-incubation with ANP. The results suggest that proliferation of VSMC is regulated by some interaction between AGT II and ANP. 相似文献
267.
268.
Although the acyl groups of phosphatidylserine in brain are uniquely enriched in docosahexaenoic acid (22:6n3), the mechanism for this enrichment is not well understood. When rat brain homogenates and microsomes were incubated in the presence of lysophosphatidylserine (LPS) together with [14C]22:6n3 and cofactors for activation to its acylCoA, very little radioactivity was incorporated into phosphatidylserine (PS). On the other hand, [14C]20:4n6 was more actively incorporated into PS. Addition of LPS (1-10 uM), however, resulted in a 2-5 fold enhancement of the transfer of labeled 22:6n3 and 20:4n6 to phosphatidic acid (PA). Kinetic analysis indicated the ability of LPS to lower the Km and increase the Vmax of the lysophosphatidic acid (LPA) acyltransferase reaction. Among other lysophospholipids tested, lysophosphatidylserine was most effective in enhancing PA biosynthesis. Since PA is an important intermediate for de novo biosynthesis of phospholipids, these results reveal a novel mechanism for promoting synthesis of PA enriched in polyunsaturated fatty acids in brain. 相似文献
269.
Conformational epitope on gp120 important in CD4 binding and human immunodeficiency virus type 1 neutralization identified by a human monoclonal antibody. 总被引:51,自引:35,他引:16
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D D Ho J A McKeating X L Li T Moudgil E S Daar N C Sun J E Robinson 《Journal of virology》1991,65(1):489-493
A human monoclonal antibody designated 15e is reactive with the envelope glycoprotein (gp120) of multiple isolates of human immunodeficiency virus type 1 (HIV-1). Antibody 15e also neutralizes HIV-1 with broad specificity and blocks gp120 binding to CD4. Characterization of the 15e epitope shows that it is conformation dependent and is distinct from previously recognized functional domains of gp120, suggesting that this epitope represents a novel site important for HIV-1 neutralization and CD4 binding. These findings have implications for the development of a vaccine for AIDS. 相似文献
270.
Isolation and Characterization of a UDPGlucose: Flavonol O-Glucosyltransferase from Illuminated Red Cabbage (Brassica oleracea cv Red Danish) Seedlings
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A UDPGlc:flavonol O3-glucosyltransferase (EC 2.4.1.91) that catalyzes the formation of quercetin and kaempferol O3-glucosides has been purified about 1450-fold from illuminated red cabbage (Brassica oleracea cv Red Danish) seedlings with a 3.3% yield. Purification of the enzyme was achieved by (NH4)2SO4-precipitation, gel-filtration, ion-exchange chromatography on DEAE-Bio-Gel and Q-Sepharose, chromatofocusing, and electrophoresis in nondenaturing polyacrylamide (10%) gels. The enzyme preparation had a pH optimum between 5.8 and 6.2, isoelectric point in the pH range 4.25 to 4.55, a Mr of 59,000, and it was composed of two similar subunits of Mr 29,500. The glucosyltransferase reached half substrate saturation at 180 micromolar (UDPGlc) and 7 micromolar (quercetin) concentrations. Kaempferol, which was glucosylated at a relative rate of 87%, had a lesser affinity for the enzyme (Km~12 micromolar). Flavanones, flavanols, flavones, dihydroflavonols, and anthocyanidins were not readily utilized as substrates, suggesting that the enzyme is specific for flavonol glucoside biosynthesis. 相似文献