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31.
Analysis of DNA sequences of 132 introns and 140 exons from 42 pairs of orthologous genes of mouse and rat was used to compare
patterns of evolutionary change between introns and exons. The mean of the absolute difference in length (measured in base
pairs) between the two species was nearly five times as high in the case of introns as in the case of exons. The average rate
of nucleotide substitution in introns was very similar to the rate of synonymous substitution in exons, and both were about
three times the rate of substitution at nonsynonymous sites in exons. G+C content of introns and exons of the same gene were
correlated; but mean G+C content at the third positions of exons was significantly higher than that of introns or positions
1–2 of exons from the same gene. G+C content was conserved over evolutionary time, as indicated by strong correlations between
mouse and rat; but the change in G+C content was greatest at position 3 of exons, intermediate in introns, and lowest at positions
1–2 in introns.
Received: 23 December 1996 / Accepted: 1 April 1997 相似文献
32.
Meredith F. Small 《International journal of primatology》1981,2(1):91-95
Using weight and skinfold thickness to calculate relative body fat, the fat content of 21 captive female rhesus macaques was
estimated. Although age and. pregnancy had no effect on fat, rank was significant, especially during winter, with high-rank
females having the highest fat scores. Rank therefore has a significant effect on the health of captive animals and may also
affect the health of individuals in feral groups. 相似文献
33.
K Hoffken I D Meredith R A Robins R W Baldwin C J Davies R W Blamey 《BMJ (Clinical research ed.)》1977,2(6081):218-220
In a retrospective study in women with breast cancer circulating immune complex levels were measured by radioimmunoprecipitation with 125I-Clq. Before operation all the patients showed plasma immune complex levels significantly higher than those in controls. Twelve months after mastectomy patients identified clinicopathologically as having a good prognosis had almost normal levels of immune complexes. By contrast, patients with detectable dissemination on diagnosis or those who died within 22 months after mastectomy had significantly raised plasma levels. The tumour-specific nature of the immune complexes detected remains to be shown and suggestions about the applicability of this test not only for prognosis but also for monitoring the course of malignant diseases need to be confirmed by further investigations. 相似文献
34.
The report of R. J. Gillies, M. P. Rosenberg, and D. W. Deamer (1981, J. Cell. Phys., 108, 115–122) that sea urchin fertilization acid is anaerobically produced CO2, was reinvestigated by inseminating Strongylocentrotus purpuratus eggs in HCO?3-free seawater, then bubbling the seawater with N2 to remove volatile acid. Fertilization acid production occurred in HCO?3-free seawater and with N2-bubbling, the pH rose 0.28 ± 0.08 unit, significantly less than the rise of 0.63 ± 0.14 unit during N2-bubbling of HCO?3-free seawater that had been acidified with CO2 and similar to the rise of 0.18 ± 0.07 unit when acidification was with HCl. We conclude that most, if not all, of the sea urchin fertilization acid is nonvolatile and thus is not CO2; since it is not a weak acid, it must be H+. 相似文献
35.
A review of the salt sensitivity of the Australian freshwater biota 总被引:13,自引:7,他引:6
Barry T. Hart Paul Bailey Rick Edwards Kent Hortle Kim James Andrew McMahon Charles Meredith Kerrie Swadling 《Hydrobiologia》1991,210(1-2):105-144
In Victoria, Australia, both dryland salinity and salinity in irrigation regions are serious agricultural problems. One option
to control the latter is to pump groundwater to maintain it below the surface. However, this leaves a saline wastewater for
disposal, probably into local streams or wetlands. This review of the salt sensitivity of the biota of Australian streams
and wetlands gives information of interest to those responsible for developing controls on these discharges. The review addresses
the lethal and sub-lethal effects of salinity on microbes (mainly bacteria), macrophytes and micro-algae, riparian vegetation,
invertebrates, fish, amphibians, reptiles, mammals, and birds. Data suggest that direct adverse biological effects are likely
to occur in Australian river, stream and wetland ecosystems if salinity is increased to around 1 000 mg L−1. The review highlights a general lack of data on the sensitivity of freshwater plants and animals to salinity increases. 相似文献
36.
R McKenna J Galante F Bachmann D L Wallace P S Kaushal P Meredith 《BMJ (Clinical research ed.)》1980,280(6213):514-517
A prospective study of patients undergoing total knee replacement was carried out by using a combination of 125I-fibrinogen scanning and phlebography, and showed a high incidence of venous thromboembolic disease (TE). Ventilation-perfusion lung scanning was performed to detect pulmonary emboli in most patients. High doses of aspirin and an intermittent low-pressure pneumatic compression device (IPCD) were effective, even in women, in preventing TE. Low doses of aspirin and placebo were equally ineffective in preventing TE. Lung-scan abnormalities compatible with pulmonary emboli were found in six out of 10 patients with isolated calf-vein thrombi. Conventional tests of platelet function did not predict the development of TE. No significant differences were found between the patients receiving low and high doses of aspirin with respect to the mean template bleeding time or platelet aggregation in response to adenosine diphosphate, collagen, and epinephrine, although these variables were significantly abnormal in the two groups receiving aspirin compared with those treated with placebo and the IPCD. Thus high doses of aspirin and a new low-pressure IPCD were effective in preventing venous TE in patients (predominantly women) undergoing total knee replacement. 相似文献
37.
38.
Nitrogen fixation and assimilation in nodules and roots were studied in soybean (Glycine max L.) exposed to different levels of aluminium (Al) stress (0, 50, 200 and 500 μM). Al at 500 μM induced oxidative stress,
which became evident from an increase in lipid peroxidation accompanied by a concomitant decline in antioxidant enzyme activities
and leghaemoglobin breakdown. Consequently, there was also a reduction in nitrogenase activity. However, the leghaemoglobin
levels and nitrogenase activity were unexpectedly found to be higher in nodules when the plants were treated with 200 μM Al.
Of the enzymes involved in nitrogen assimilation, the activity of glutamate dehydrogenase-NADH was reduced in nodules under
Al stress, but it was significantly higher in roots at 500 μM Al as compared to that in the control. In nodules, the glutamine
synthetase/glutamate synthase-NADH pathway, assayed in terms of activity and expression of both the enzymes, was inhibited
at >50 μM Al; but in roots this inhibitory effect was apparent only at 500 μM Al. No significant changes in ammonium and protein
contents were recorded in the nodules or roots when the plants were treated with 50 μM Al. However, Al at ≥200 μM significantly
increased the ammonium levels and decreased the protein content in the nodules. But these contrasting effects on ammonium
and protein contents due to Al stress were observed in the roots only at 500 μM Al. The results suggest that the effect of
Al stress on nitrogen assimilation is more conspicuous in nodules than that in the roots of soybean plants. 相似文献
39.
Research across groups and methods consistently finds a gender difference in patterns of specificity of genital response; however, empirically supported mechanisms to explain this difference are lacking. The information-processing model of sexual arousal posits that automatic and controlled cognitive processes are requisite for the generation of sexual responses. Androphilic women’s gender-nonspecific response patterns may be the result of sexually-relevant cues that are common to both preferred and nonpreferred genders capturing attention and initiating an automatic sexual response, whereas men’s attentional system may be biased towards the detection and response to sexually-preferred cues only. In the present study, we used eye tracking to assess visual attention to sexually-preferred and nonpreferred cues in a sample of androphilic women and gynephilic men. Results support predictions from the information-processing model regarding gendered processing of sexual stimuli in men and women. Men’s initial attention patterns were gender-specific, whereas women’s were nonspecific. In contrast, both men and women exhibited gender-specific patterns of controlled attention, although this effect was stronger among men. Finally, measures of attention and self-reported attraction were positively related in both men and women. These findings are discussed in the context of the information-processing model and evolutionary mechanisms that may have evolved to promote gendered attentional systems. 相似文献
40.