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排序方式: 共有396条查询结果,搜索用时 15 毫秒
1.
GPC phosphodiesterase and phosphomonoesterase activities of renal cortex and medulla of control, antidiuresis and diuresis rats 总被引:1,自引:0,他引:1
Glycerylphosphorylcholine (GPC) concentration was reported to be elevated in renal medulla of experimental animals deprived of water. The activities of GPC phosphodiesterases were similar in homogenates and membrane subfractions of renal cortex prepared from control, diuresis and antidiuresis rats. There were no differences in these preparations' ability to hydrolyze phosphorylcholine. In contrast, there was a nearly 50% reduction of non-specific phosphomonoesterase activity, using p-nitrophenylphosphate as substrate and membrane subfractions prepared from the antidiuresis animals. It is suggested that as a consequence, a pathway for the formation from L-alpha-glycerylphosphate is activated. 相似文献
2.
A kairomone in the frass and vomitus of larvae ofAgrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) triggered larviposition activity in its habitual parasitoidBonnetia comta (Fallen) (Diptera: Tachinidae). Laboratory bioassays showed that no measurable differences existed in the larviposition-stimulating activity of frass fromA. ipsilon larvae reared on 3 different food sources. In other tests, corn seedlings damaged by late-instar larvae ofA. ipsilon elicited strong larviposition activity inB. comta; other corn seedlings damaged with a razor blade did not elicit strong activity. Frass aged for 8-days was only slightly less effective at releasing a larviposition response when compared to fresh frass.B. comta was not stimulated to larviposit by oven dried frass or an India ink dot the color and shape of a fresh pellet from a host larva. The host habitat location and host finding process forB. comta and other tachinid species that deposit free-living maggots is discussed. 相似文献
3.
N-Hydroxylaminopurines are highly mutagenic for growing as well as resting Salmonella typhimurium strain TA100 and to a lesser extent for strain TA98. Aminopurines, under similar conditions, are not mutagenic. N-Methylhydroxylaminopurine, under similar conditions, exhibits only minimal activity. The results are taken to indicate that unlike non-hydroxylated aminopurines, N-hydroxylaminopurines exert their mutagenicity not by acting as base analogs but by direct covalent binding with DNA-guanine. 相似文献
4.
Hardies SC; Martin SL; Voliva CF; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1986,3(2):109-125
5.
A spring bloom of diatoms which occurred in large enclosed ecosystem bags at Loch Ewe, Scotland, during 1980, has been the subject of a chemical study. Changes observed in the general biochemical composition of the diatoms during the bloom are compared with the species distribution and changes in the nutrient chemistry of the bag water. The results indicate that major changes in cell biochemistry are associated with the growth, development, and decay of a diatom bloom, particularly if one or more nutrients become limiting. 相似文献
6.
Molecular analysis of the composition of the bifidobacterial and lactobacillus microflora of humans. 总被引:23,自引:10,他引:13
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The bifidobacterial and lactobacillus populations of fecal samples collected from two human subjects during a 12-month period were studied. The total numbers of bifidobacteria were stable throughout the study period in both subjects, but lactobacillus numbers were less constant. Analysis of the composition of the bifidobacterial populations by using ribotyping or pulsed-field gel electrophoresis to differentiate between bacterial strains demonstrated major differences between the subjects. Subject 1 harbored five strains of bifidobacteria throughout the 12-month period, and one strain was numerically predominant. In contrast, subject 2 harbored a more complex bifidobacterial population (five to six strains per sample) whose composition fluctuated throughout the 12 months. One lactobacillus strain was numerically predominant throughout the study in both subjects. Strains of bifidobacteria and lactobacilli common to both subjects were not detected. 相似文献
7.
A major difference between the divergence patterns within the lines-1 families in mice and voles 总被引:3,自引:0,他引:3
Vanlerberghe F; Bonhomme F; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1993,10(4):719-731
L1 retroposons are represented in mice by subfamilies of interspersed
sequences of varied abundance. Previous analyses have indicated that
subfamilies are generated by duplicative transposition of a small number of
members of the L1 family, the progeny of which then become a major
component of the murine L1 population, and are not due to any active
processes generating homology within preexisting groups of elements in a
particular species. In mice, more than a third of the L1 elements belong to
a clade that became active approximately 5 Mya and whose elements are >
or = 95% identical. We have collected sequence information from 13 L1
elements isolated from two species of voles (Rodentia: Microtinae: Microtus
and Arvicola) and have found that divergence within the vole L1 population
is quite different from that in mice, in that there is no abundant
subfamily of homologous elements. Individual L1 elements from voles are
very divergent from one another and belong to a clade that began a period
of elevated duplicative transposition approximately 13 Mya. Sequence
analyses of portions of these divergent L1 elements (approximately 250 bp
each) gave no evidence for concerted evolution having acted on the vole L1
elements since the split of the two vole lineages approximately 3.5 Mya;
that is, the observed interspecific divergence (6.7%-24.7%) is not larger
than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses
showed no clustering into Arvicola and Microtus clades.
相似文献
8.
Brian K. Speake Ruth J. McCartney Marieke Feast André Maldjian Raymond C. Noble 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》1996,115(4):493-499
Although substantial information is available regarding the fatty acid composition of lipids of the yolk and of the developing tissues of the chicken embryo, there is little knowledge on this topic for other avian species. The aim of the present study was to compare the yolk and embryonic tissue fatty acid profiles for a species selecting its food in the wild (the lesser black backed gull) with one fed on a standard commercial diet (the commercially reared pheasant). The fatty acid compositions of the yolk lipids were determined, and major differences were observed between the two species. In particular, the phospholipid of the gull yolk was enriched in 20:4n-6 and 22:6n-3 (18.8 and 7.1%, respectively, by weight of total fatty acids) in comparison with the pheasant (4.0 and 4.1%, respectively). The fatty acid compositions of the embryonic tissues were determined using eggs incubated in the laboratory. For the liver and heart, the fatty acid composition of the lipids in the two species reflected the initial yolk composition, with the gull tissue lipids generally containing higher proportions of 20:4n-6 and 22:6n-3 than those of the pheasant. In contrast, the fatty acid profiles of the brain phospholipid were essentially identical in the two species, with 20:4n-6 and 22:6n-3 comprising approximately 9 and 17%, respectively, of total fatty acids in both cases. 相似文献
9.
Isolation of Mutations in the Drosophila Homologues of the Human Neurofibromatosis 2 and Yeast Cdc42 Genes Using a Simple and Efficient Reverse-Genetic Method 总被引:2,自引:0,他引:2
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Reverse genetic analysis in Drosophila has been greatly aided by a growing collection of lethal P transposable element insertions that provide molecular tags for the identification of essential genetic loci. However, because the screens performed to date primarily have generated autosomal P-element insertions, this collection has not been as useful for performing reverse genetic analysis of X-linked genes. We have designed a reverse genetic screen that takes advantage of the hemizygosity of the X chromosome in males together with a cosmid-based transgene that serves as an autosomally linked duplication of a small region of the X chromosome. The efficacy and efficiency of this method is demonstrated by the isolation of mutations in Drosophila homologues of two well-studied genes, the human Neurofibromatosis 2 tumor suppressor and the yeast CDC42 gene. The method we describe should be of general utility for the isolation of mutations in other X-linked genes, and should also provide an efficient method for the isolation of new alleles of existing X-linked or autosomal mutations in Drosophila. 相似文献
10.
Molecular phylogeny and divergence times of drosophilid species 总被引:32,自引:15,他引:17
The phylogenetic relationships and divergence times of 39 drosophilid
species were studied by using the coding region of the Adh gene. Four
genera--Scaptodrosophila, Zaprionus, Drosophila, and Scaptomyza (from
Hawaii)--and three Drosophila subgenera--Drosophila, Engiscaptomyza, and
Sophophora--were included. After conducting statistical analyses of the
nucleotide sequences of the Adh, Adhr (Adh-related gene), and nuclear rRNA
genes and a 905-bp segment of mitochondrial DNA, we used Scaptodrosophila
as the outgroup. The phylogenetic tree obtained showed that the first major
division of drosophilid species occurs between subgenus Sophophora (genus
Drosophila) and the group including subgenera Drosophila and Engiscaptomyza
plus the genera Zaprionus and Scaptomyza. Subgenus Sophophora is then
divided into D. willistoni and the clade of D. obscura and D. melanogaster
species groups. In the other major drosophilid group, Zaprionus first
separates from the other species, and then D. immigrans leaves the
remaining group of species. This remaining group then splits into the D.
repleta group and the Hawaiian drosophilid cluster (Hawaiian Drosophila,
Engiscaptomyza, and Scaptomyza). Engiscaptomyza and Scaptomyza are tightly
clustered. Each of the D. repleta, D. obscura, and D. melanogaster groups
is monophyletic. The splitting of subgenera Drosophila and Sophophora
apparently occurred about 40 Mya, whereas the D. repleta group and the
Hawaiian drosophilid cluster separated about 32 Mya. By contrast, the
splitting of Engiscaptomyza and Scaptomyza occurred only about 11 Mya,
suggesting that Scaptomyza experienced a rapid morphological evolution. The
D. obscura and D. melanogaster groups apparently diverged about 25 Mya.
Many of the D. repleta group species studied here have two functional Adh
genes (Adh-1 and Adh-2), and these duplicated genes can be explained by two
duplication events.
相似文献