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91.
Resting cortisol levels and the emergence of dominant status among male vervet monkeys 总被引:1,自引:0,他引:1
Resting serum cortisol was measured in adult male vervet monkeys (Cercopithicus aethiops sabaeus) in four different conditions: (1) among groups with unaltered group membership and established dominance hierarchies; (2) among groups from which the original dominant male had been removed and in which the remaining males competed for dominant status; (3) among newly formed groups of three unfamiliar males each of which had been the dominant male in his previous group; and (4) among groups from which a dominant male was temporarily separated and returned. In Condition 1, cortisol concentrations did not differ between dominant and subordinate males. The second condition showed that cortisol levels were highest among males who eventually emerged as the dominant male. In the third condition, however, cortisol levels did not differentiate eventually dominant from eventually subordinate males. In the last condition, cortisol levels were highest in the animals that became or remained dominant following reintroduction. These data indicate that cortisol concentration does not differ between dominant and subordinate males in stable groups and that cortisol rises during competition for dominance among familiar males. 相似文献
92.
93.
A biological measure of space available within substrates was used as an index to examine substrate selection by the stonefly nymph Paragnetina media (Walker). Physical measures, such as total surface area of substrate, have not worked well in the past in explaining distribution of aquatic invertebrates. Although analysis of habitable space within substrate did not explain selection completely, the technique provided a precise measure and might be a more rigorous means by which substrate selection could be examined. 相似文献
94.
Philip Skehan James E. Thomas Susan J. Friedman 《In vitro cellular & developmental biology. Plant》1986,22(11):632-636
Summary Sarcoma 180 monolayers spontaneously shed single cells and small multicellular aggregates into the surrounding medium to produce
a dual population of floating and substratum-attached cells. Shedding was a motility-associated event that occurred when cells
attempted to migrate over one another. It resulted from a combination of cell shape change and active motility, which increased
sensitivity to fluid shear dislodgement by reducing a cell's surface area of adhesive contact and increasing strain tension
at its adhesive contact points. Shedding occurred at all phases of the cell cycle. Extracellular matrix but not conditioned
medium enhanced the floating subpopulation by slowing the kinetics of rattachment to plastic and cellular substrata. Although
sarcoma 180 cells are anchorage independent in the sense that they grow readily in single cell suspension, they nevertheless
exhibited anchorage modulation of their cell cycle. Short periods in suspension produced a mild G1 accumulation, whereas longer periods of anchorage deprivation led to a mild G2 accumulation which appeared to result from an interference with cytokinesis.
This work was supported by grants from the Medical Research Council of Canada, The National Cancer Institute of Canada, the
Alberta Heritage Savings and Trust Fund for Applied Cancer Research, and the Alberta Heritage Fund for Medical Research. 相似文献
95.
Social relationships between mothers and juvenile offspring were examined in captive, socially-living vervet monkeys (Cercopithecus aethiops sabaeus) to assess the effects of offspring age and sex, and the mother's dominance rank on behavioural interactions. The results indicate that both high-and low-ranking mothers approach and groom their daughters more than they approach and groom their sons. The frequency of both aggressive behaviour toward offspring and support of offspring in agonistic encounters with other group members is influenced by the mother's dominance rank, but not by offsprin sex. Compared to sons, daughters (particularly daughters of high-ranking females) approach and groom their mothers more often, and support their mothers more often in intra-group aggression. The results are discussed in terms of several predictions from parental investment theory and the concept of mutualism. 相似文献
96.
Summary Derivatives of Escherichia coli K-12 carrying a deletion of the recA gene survive exposure to UV (254 nm) better if they also contain the lexA41 mutation which codes for a labile LexA protein. This effect of the lexA41 mutation is not observed in comparable strains carrying a uvr A6 mutation. Using two independent methods to detect pyrimidine dimers we found that UV irradiated RecA deficient cells removed dimers from their DNA more rapidly if they contained the lexA41 mutation than if the contained the wild-type lexA gene. Our results are consistent with the idea that a relatively high level of UvrABC incision nuclease resulting from inefficient repression of the corresponding genes by the labile LexA41 protein facilitates excision of pyrimidine dimers from the DNA of UV irradiated cells. 相似文献
97.
To examine the sensitivities of partially purified dopamine receptors to various dopaminergic agonists and antagonists, canine brain striatum dopamine receptors were enriched by isoelectric focusing. The digitonin-solubilized receptors were prelabelled with [3H]spiperone and focused for two time periods. After 5 h (incomplete focusing), radioactive peaks were detected at pH 6 and 9-11. Only the pH 6 peak revealed drug sensitivities expected of D2 receptors. Receptor recovery of the pH 6 peak was 79% with purification being sevenfold. After focusing overnight to equilibrium, the pH 6 peak further separated into peaks at pH 4.6 and 6.8. The receptor was identified only in the pH 4.6 fraction. The recovery of receptors in the pH 4.6 peak was low (10%), indicating little enrichment of the receptor. The rank order of binding of neuroleptics and dopamine agonists to the purified material was similar to that of the original preparation of soluble receptors. Dopamine did not bind to the purified pH 4.6 fraction unless the phosphate buffer (used during focusing) was replaced with Tris buffer. The absence of receptors in the pH 6.8 and pH 10 fractions, although both contained prelabeled [3H]spiperone, indicates the importance of testing agonists and antagonists on each fraction at each step in purification. 相似文献
98.
Philip Skehan Susan J. Friedman 《In vitro cellular & developmental biology. Plant》1985,21(5):288-290
Summary A rapid method has been developed for measuring the cellular protein content of mono- and multilayered anchorage cultures.
Fixed or air dried cultures are stained for 30 min with 0.2% Naphthol Yellow S (NYS) dissolved in 1% acetic acid. Unbound
dye is removed by a series of four 2.5 min washes in 1% acetic acid, and protein-bound dye extracted with 10 mM unbuffered Tris base for spectrophotometric optical density determination at 433 nm. The NYS method exhibited a least-squares
correlation coefficient of 0.99997 with the Oyama-Eagle Lowry method. 相似文献
99.
A method is described which allows a large number of bacterial strains to be rapidly and easily screened for the presence of site-specific endonucleases. The method involves selective permeabilization of the bacterial cell and analysis of the exuded material. Type II restriction endonucleases from cyanobacteria and Gram-negative eubacteria have been detected and new enzymes have been found. The method should be widely applicable and easy to modify for use in genera other than those tested. Three-site-specific endonuclease activities, detected by this method in Aphanothece halophytica PCC 7412, were purified and their recognition and cleavage specificities were determined AhaI and AhaII recognise and cleave the same DNA sequences as CauII and AcyI respectively; the specificity of AhaIII (TTTAAA) has been reported previously (Whitehead and Brown, 1982, FEBS Letters 143:296–300).Abbreviations Brij-58
20 cetyl ether
- Pu
purine nucleoside
- Py
pyrimidine nucleoside 相似文献
100.
DNA probe localization at 18p113 band by in situ hybridization and identification of a small supernumerary chromosome 总被引:46,自引:9,他引:37
M. G. Mattei N. Philip E. Passage J. P. Moisan J. L. Mandel J. F. Mattei 《Human genetics》1985,69(3):268-271
Summary Recombinant plasmid clone B74 (also named D18S3) containing a human single-copy DNA segment of 6 kilobases (kb) was localized by in situ hybridization on band p113 of chromosome 18. This probe was then used in cytogenetic diagnosis to identify precisely a small supernumerary chromosome as an isochromosome i(18p). 相似文献