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1.
Dominant males of nonseasonally breeding species should have more opportunity than seasonal breeders to monopolize access to estrous females and thus enhance their reproductive success. They may also use other strategies for maximizing reproductive success such as producing offspring by relatively high ranking females. To test these hypotheses, the paternity of 35 (80%) of 44 Macaca fascicularis offspring, born over a 28-month period, was established using electrophoretically and serologically defined genetic markers. The social ranks of each of the seven potential fathers and 26 potential mothers were determined by recording outcomes of dyadio agonistic interactions. No evidence could be found to support either hypothesis. Further, in view of previously reported significant, positive correlations between male social rank and sexual activity rates in this study group, sexual activity rates do not appear to predict the number of offspring a male sires in this species. 相似文献
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3.
Chromosomal location and cloning of the gene (trmD) responsible for the synthesis of tRNA (m1G) methyltransferase in Escherichia coli K-12 总被引:5,自引:0,他引:5
Summary The trmD gene, which governs the formation of 1-methyl-guanosine (m1G) in transfer ribonucleic acid (tRNA), has been located by phage P1 transduction at 56 min on the chromosomal map of Escherichia coli. Cotransduction to tyrA at 56 min is 80%. From the Clarke and Carbon collection a ColE1-tyrA
+ hybrid plasmid was isolated, which carried the trmD
+ gene and was shown to over-produce the tRNA (m1G)methyltransferase. By subcloning restriction enzyme fragments in vitro, the trmD
+ gene was located to a 3.4 kb DNA fragment 6.5 kb clockwise from the tyrA
+ gene. The mutation trmD1, which renders the tRNA (m1G) methyltransferase temperaturesensitive both in vivo and in vitro could be complemented by trmD
+ plasmids. These results suggest that the gene trmD
+ is the structural gene for the tRNA (m1G)methyltransferase (EC 2.1.1.3.1). 相似文献
4.
Roy Ronen Glenn Tesler Ali Akbari Shay Zakov Noah A. Rosenberg Vineet Bafna 《PLoS genetics》2015,11(9)
Methods for detecting the genomic signatures of natural selection have been heavily studied, and they have been successful in identifying many selective sweeps. For most of these sweeps, the favored allele remains unknown, making it difficult to distinguish carriers of the sweep from non-carriers. In an ongoing selective sweep, carriers of the favored allele are likely to contain a future most recent common ancestor. Therefore, identifying them may prove useful in predicting the evolutionary trajectory—for example, in contexts involving drug-resistant pathogen strains or cancer subclones. The main contribution of this paper is the development and analysis of a new statistic, the Haplotype Allele Frequency (HAF) score. The HAF score, assigned to individual haplotypes in a sample, naturally captures many of the properties shared by haplotypes carrying a favored allele. We provide a theoretical framework for computing expected HAF scores under different evolutionary scenarios, and we validate the theoretical predictions with simulations. As an application of HAF score computations, we develop an algorithm (PreCIOSS: Predicting Carriers of Ongoing Selective Sweeps) to identify carriers of the favored allele in selective sweeps, and we demonstrate its power on simulations of both hard and soft sweeps, as well as on data from well-known sweeps in human populations. 相似文献
5.
Penicillium camembertii was mutated and screened for cyclopiazonic acid-negative mutants. With a simple and rapid mini-extraction method for detection of cyclopiazonic acid production, we were able to isolate two strains which were affected in the production of this metabolite. One strain had completely lost the ability to synthesize detectable amounts of this secondary metabolite, whereas the other mutant produced 50 to 100 times less cyclopiazonic acid than the wild type. Also, the former strain had a changed morphology compared with the wild type. This morphological alteration appears to be coupled to the inability to produce cyclopiazonic acid because morphological revertants were able to synthesize cyclopiazonic acid to a level comparable to the wild type. The second mutant accumulated a new metabolite which was detectable by two-dimensional thin-layer chromatography. This new metabolite, however, appears not to be a direct precursor of cyclopiazonic acid. 相似文献
6.
The effect of single intraperitoneal 1 g.kg-1 doses of a solution of 20 amino acids (AA) on food intake was investigated in 20 piglets examined repeatedly between 2 and 26 days of age. The animals were reared individually from day 1 after birth in cages and bottle-fed a liquid diet nine times per day at two-hour intervals from 6 to 22 h. Although amino acid administration did not significantly affect plasma concentrations of total free AA throughout the experiment (as measured just before and 2 and 5 h after AA administration in blood withdrawn from the external jugular vein) it did produce a downward trend in food intake of piglets at 9-10 d of age. In older animals, the depressive effect on food intake was significantly greater and lasted longer. It is suggested that the aminostatic component of food intake regulation in piglets does not begin to operate until the weaning period. 相似文献
7.
Glenn C. Conroy 《International journal of primatology》1987,8(2):115-137
Body-weight estimates of fossil primates are commonly used to infer many important aspects of primate paleobiology, including
diet, ecology, and relative encephalization. It is important to examine carefully the methodologies and problems associated
with such estimates and the degree to which one can have confidence in them. New regression equations for predicting body
weight in fossil primates are given which provide body-weight estimates for most nonhominid primate species in the fossil
record. The consequences of using different subgroups (evolutionary “grades”) of primate species to estimate fossil-primate
body weights are explored and the implications of these results for interpreting the primate fossil record are discussed.
All species (fossil and extant) were separated into the following “grades”: prosimian grade, monkey grade, ape grade, anthropoid
grade, and all-primates grade. Regression equations relating lower molar size to body weight for each of these grades were
then calculated. In addition, a female-anthropoid grade regression was also calculated for predicting body weight infernales
of extinct, sexually dimorphic anthropoid species. These equations were then used to generate the fossil-primate body weights.
In many instances, the predicted fossil-primate body weights differ substantially from previous estimates. 相似文献
8.
9.
Evolution of the Ribosomal DNA Spacers of Drosophila melanogaster : Different Patterns of Variation on X and Y Chromosomes 总被引:4,自引:3,他引:1
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Length variation of the ribosomal gene spacers of Drosophila melanogaster was studied. Analysis of 47 X chromosomal and 47 Y chromosomal linked rDNA arrays collected from five continents indicates that the arrays on the two chromosomes differ qualitatively. The Y-linked arrays from around the world share little or no similarity for either their overall length or the organization of their spacers. Most of the X-linked arrays do, however, share a major length spacer of 5.1 kb. In addition, those X-linked arrays that have a major 5.1-kb band have similar spacer organization as demonstrated by genomic DNA digestions with several restriction enzymes. These data strongly support the hypothesis that spacer length patterns on only X-linked genes are maintained primarily by natural selection. 相似文献
10.
Non-motile mutants of Rhizobium trifolii defective in either flagellar synthesis or function were isolated by transposon Tn5 mutagenesis. they were indistinguishable from motile control strains in growth in both laboratory media and in the rhizosphere of clover roots. When each non-motile mutant was grown together with a motile strain in continuous culture, the numbers of motile and non-motile organisms remained in constant proportion, implying that their growth rates were essentially identical. When inoculated separately onto clover roots, the mutants and wildtype did not differ significantly in the number of nodules produced or in nitrogen fixing activity. However, when mixtures of equal numbers of mutant and wild-type cells were inoculated onto clover roots, the motile strain formed approximately five times more nodules than the flagellate or non-flagellate, non-motile mutants, suggesting that motility is a factor in competition for nodule formation. 相似文献