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31.
The amount of DNA per haploid genome, the C-value, is often directly correlated with nuclear and cell volume, but inversely correlated with cell replication rate. Also, rates of cellular growth sometimes appear to be correlated with organismal developmental rates and life history patterns. Among vertebrates, salamanders exhibit the greatest variation in genome size. In the present study we have examined interspecific and intraspecific variation in blood cell DNA levels in the genus Desmognathus, which shows greater variation in life history traits than any other salamander genus. Specimens of Desmognathus quadramaculatus, D. monticola, D. ochrophaeus and D. wrighti were collected from nature at two localities in the southern Appalachian Mountains. Estimates of genome size in pg of DNA were obtained from blood smears by DNA-Feulgen cytophotometry, using erythrocyte nuclei of Xenopus laevis as an internal reference standard of 6.35 pg DNA per cell. C-values of Desmognathus are the smallest in the order Caudata. Although significant variation in DNA levels was found among the four species, the differences were small, and do not support previously proposed relationships between C-value and life-history variation. 相似文献
32.
P Braquet N Senn M Fagoo R Garay J P Robin A Esanu E Chabrier T Godfrain 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1986,302(12):443-448
Lignans are natural products, some of which were recently discovered in animal urines, semen and blood plasma. We investigated the actions of animal lignans obtained by total synthesis or extracted from urines of pregnant women on Na+, K+-ATPase in human red cells and human and guinea-pig heart cell membranes. Some of the tested lignans (enterolactone, prestegane B and 3-O-methyl enterolactone) inhibited Na+, K+-pump activity in human red cells with IC50 ranging from 5 to 9 X 10(-4) M. The IC50 for ouabain (7 X 10(-7) M) was not modified by addition of lignans. Enterolactone inhibited Na+, K+-ATPase activity in human and guinea pig heart membranes. It also displaced [3H]-ouabain binding from human heart with IC50 = 1.5 X 10(-4) M. The apparent dissociation rate constants (kd) of [3H]-ouabain were not different in presence of digoxin or enterolactone. Enterolactone exhibited a poor cross reactivity against antidigoxin antibodies. The aglycones of the lignans studied here were slight inhibitors of the Na+, K+-ATPase. However, we cannot exclude that a glycosyl- (and/or butenolide-) derivative of enterolactone could be one "endogenous ouabain-like" factor. 相似文献
33.
Robin A. Woods Darlene G. Roberts Theodore Friedman Douglas Jolly David Filpula 《Molecular & general genetics : MGG》1983,191(3):407-412
Summary Yeast mutants lacking activity of the enzyme hypoxanthine: guanine phosphoribosyltransferase (H:GPRT) have been isolated by selecting for resistance to 8-azaguanine in a strain carrying the wild type allele, ade4
+ of the gene coding for amidophosphoribosyltransferase (PRPPAT), the first enzyme of de novo purine synthesis. The mutants excrete purines and are cross-resistant to 8-azaadenine. They are recessive and represent a single complementation group, designated hpt1. Ade4-su, a prototrophic allele of ade4 with reduced activity of PRPPAT, is epistatic to hpt1, suppressing purine excretion and resistance to azaadenine but not resistance to azaguanine. The genotype ade2 hpt1 does not respond to hypoxanthine. Hpt1 complements and is not closely linked to the purine excreting mutants pur1 to pur5. Hpt1 and pur6, a regulatory mutant of PRPPAT, are also unlinked but do not complement, suggesting a protein-protein interaction between H:G-PRT and PRPPAT. Mycophenolic acid (MPA), an inhibitor of de novo guanine nucleotide synthesis, inhibits the growth of hpt1 and hpt1
+. Xanthine allows both genotypes to grow in the presence of MPA whereas guanine only allows growth of hpt1
+. Activity of A-PRT, X-PRT and H:G-PRT is present in hpt
+. Hpt1 lacks activity of H:G-PRT but has normal A-PRT and X-PRT. 相似文献
34.
Robin Huw Crompton 《Primates; journal of primatology》1983,24(2):241-259
The locomotor behaviour ofGalago senegalensis andG. crassicaudatus (Primates: Lorisidae) was quantified in an 11-month field study in the Northern Transvaal of South Africa. This paper assesses
the distinction between the behaviour of adults, and that of infants at the age when they first began foraging independently,
taking into account seasonal variations in adult behaviour. Infants of both species differ significantly from adults in the
types of locomotion they use, postures, activity, support use, height of observation and tree use. While all these factors
are inter-connected, it is concluded that infants exploit a quantitatively different part of the arboreal habitat from adults,
because of factors such as locomotor maturation and gross body size. Dietary differences are also possible but the present
study cannot establish or deny this possibility. 相似文献
35.
Robin Arthur Woods 《Molecular & general genetics : MGG》1969,105(4):314-316
Summary Confirmation that the ad-2 locus of yeast controls the carboxylation of aminoimidazole ribonucleotide (AIR) to 5-amino-4-imidazole carboxylate ribonucleotide (CAIR) is provided by the observation that 21 out of a sample of 113 ad-2 mutants were affected by CO2. 19 of the mutants were stimulated by CO2 and 2 were inhibited. The majority of the CO2-stimulated mutants were confined to one section of the complementation map of the ad-2 locus. 相似文献
36.
A mutant of yeast sensitive to growth inhibition by 2,6-diaminopurine (2,6-DAP) was analyzed genetically and found to be a double mutant. One gene, dap, conferred approximately 30% sensitivity to the analogue. The other, slw, potentiated the inhibition such that the double mutant dap slw was inhibited 90%. The mutation dap conferred concomitant sensitivity to a number of other purine analogues. The activity of a purine phosphoribosyltransferase with 2,6-DAP in a strain carrying dap was found to be three times higher than in the wild type. It is inferred that the mutation alters the properties of a purine phosphoribosyltransferase. A possible mechanism for the effect of slw is also discussed. 相似文献
37.
Changes in the ribonucleic acid metabolism of aging mouse tissues with particular reference to the prostate gland 总被引:7,自引:6,他引:1 下载免费PDF全文
W. I. P. Mainwaring 《The Biochemical journal》1968,110(1):79-86
1. Mouse mast-cell tumours P815 Y and HC were shown to contain glycoprotein material composed of glucosamine, galactosamine, sialic acid, galactose and mannose. 2. The major amino acids released after acid hydrolysis of Pronase-treated digests of the glycoprotein are aspartic acid, glutamic acid, serine, threonine, proline, glycine and alanine. The Pronase-digested material is not degraded in alkaline solution. 3. On incubation of mast cells with [(35)S]sulphate, heparin is the major radioactive product. However, [1-(14)C]glucosamine and d-[(14)C]glucose are incorporated largely into the glycoprotein. 4. The fate of [(35)S]sulphate-labelled and [1-(14)C]glucosamine-labelled material was studied. In each case high-molecular-weight radioactive material is released from the cells into the culture medium. The t((1/2)) of [(35)S]sulphate-labelled material in cells is 70hr. and that of [1-(14)C]-glucosamine-labelled material in cells is 40hr. 5. About 60% of the [(35)S]sulphate-labelled material is present in the mitochondrial and granular fraction. [1-(14)C]-Glucosamine-labelled material is present in both microsomal and mitochondrial and granular fractions, [(14)C]sialic acid being concentrated in the microsomal fraction. 相似文献
38.
39.
The effect of castration on the ribonucleic acid metabolism of an experimental prostatic tumour 下载免费PDF全文
1. The incorporation of [(14)C]phenylalanine into the protein of microsomes obtained from an androgen-dependent transplantable prostatic tumour has been investigated. 2. The incorporation of [(14)C]ATP into the RNA of the nuclei from the same tumour has also been examined. 3. The castration of the host animal depresses the incorporation of both labelled compounds on subsequent incubation in vitro. 4. The uptake of phenylalanine can be markedly stimulated by polyuridylic acid only in tumours obtained from castrated host animals. 5. The tumour RNA-polymerase activity appears to be dependent on the concentrations of androgens in the host animal. 相似文献
40.
The Induction of Mitotic Recombination by Mitomycin C in Ustilago and Saccharomyces 总被引:12,自引:2,他引:10 下载免费PDF全文
Robin Holliday 《Genetics》1964,50(3):323-335