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1.
Development and evaluation of the polymerase chain reaction to detect Mycoplasma genitalium 总被引:11,自引:0,他引:11
The polymerase chain reaction (PCR) was developed to detect Mycoplasma genitalium. Oligonucleotide primers were used to amplify a 374 bp region of the attachment protein of the mycoplasma. DNA from three strains of M. genitalium tested gave a characteristic PCR product which was not seen with DNA from any other source. As little as 10(-15) g of M. genitalium DNA could be detected and it was found in the vagina of progesterone-treated BALB/c mice inoculated with M. genitalium organisms later than they could be cultured from this site, but not in mice that never became colonised vaginally. 相似文献
2.
S Gilfillan S Aiso D Smilek D L Woodland E Palmer H O McDevitt 《Journal of immunology (Baltimore, Md. : 1950)》1991,147(12):4074-4081
The effects of quantitative differences in class II cell surface expression have been difficult to address in intact animals. This study uses several lines of H-2s/s mice carrying an A beta k transgene that differ significantly in terms of class II cell surface expression. Due to inefficient chain pairing, mice carrying 60 to 65 copies of this transgene express only low levels of A alpha s/A beta k on the cell surface, and cell surface expression of the endogenous A alpha s/A beta s complex (and total Ia) is severely reduced (to 7-15% control levels). The significant decrease in class II cell surface expression in the thymic cortex of these mice did not affect the frequency of peripheral T cells expressing at least 10 distinct TCR V beta chains. However, T cell proliferative responses to the A alpha s/A beta s-restricted peptide MBP 89-101 were abrogated in high copy number A beta k mice. Experiments using bone marrow chimeras demonstrated that both inefficient Ag presentation and failure to positively select appropriate T cells contributed to this lack of response. Inefficient Ag presentation was clearly the dominant defect, and the density of class II cell surface expression required for positive selection appeared to be quite low. 相似文献
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Liver plasma membranes prepared from genetically diabetic (db/db) mice expressed levels of Gi α-2, Gi α-3 and G-protein β-subunits that were reduced by some 75, 63 and 73% compared with levels seen in membranes from lean animals. In contrast, there were no significant differences in the expression of the 42 and 45 kDa forms of Gs α-subunits. Pertussis toxin-catalysed ADP-ribosylation of membranes from lean animals identified a single 41 kDa band whose labelling was reduced by some 86% in membranes from diabetic animals. Cholera toxin-catalysed ADP-ribosylation identified two forms of Gs α-subunits whose labelling was about 4-fold greater in membranes from diabetic animals compared with those from lean animals. Maximal stimulations of adenylyl cyclase activity by forskolin (100 μM), GTP (100 μM), p[NH]ppG (100 μM), NaF (10 mM) and glucagon (10 μM) were similar in membranes from lean and diabetic animals, whereas stimulation by isoprenaline (100 μM) was lower by about 22%. Lower concentrations (EC50-60 nM) of p[NH]ppG were needed to activate adenylyl cyclase in membranes from diabetic animals compared to those from lean animals (EC50-158 nM). As well as causing activation, p[NH]ppG was capable of eliciting a pertussis toxin-sensitive inhibitory effect upon forskolin-stimulated adenylyl cyclase activity in membranes from both lean and diabetic animals. However, maximal inhibition of adenylyl cyclase activity in membranes from diabetic animals was reduced to around 60% of that found using membranes from lean animals. Pertussis toxin-treatment in vivo enhanced maximal stimulation of adenylyl cyclase by glucagon, isoprenaline and p[NH]ppG through a process suggested to be mediated by the abolition of functional Gi activity. The lower levels of expression of G-protein β-subunits, in membranes from diabetic compared with lean animals, is suggested to perturb the equilibria between holomeric and dissociated G-protein subunits. We suggest that this may explain both the enhanced sensitivity of adenylyl cyclase to stimulation by p[NH]ppG in membranes from diabetic animals and the altered ability of pertussis and cholera toxins to catalyse the ADP-ribosylation of G-proteins in membranes from these two animals. 相似文献
6.
R. G. Palmer 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,85(4):389-393
Summary Conditional lethality in soybean, Glycine max (L.) Merr., occurred in F2 plants when cytoplasmicchlorophyll mutant Genetic Type T275 was the female parent and when either nuclear mutants T253 or T323 plants were the male parents. Mutant T253 [Mdh1-n (Urbana) y20 (Urbana) k2] is missing two of three mitochondrial malate dehydrogenase isozymes [Mdh1-n (Urbana)] and has yellowish-green leaves [y20 (Urbana)] and a tan-saddle pattern seed coat (k2). Mutant T323 [Mdh1-n (Ames 2) y20 (Ames 2)] also is missing two of three mitochondrial malate dehydrogenase isozymes [Mdh1-n (Ames 2)] and has yellowishgreen leaves [y20 (Ames 2)], but has yellow seed coat (K2). Mutants T275, T253, and T323 are viable both in the field and glasshouse. The genotypes cyt-Y2 Mdh1-n (Urbana) y20 (Urbana) k2/Mdh1-n (Urbana) y20 (Urbana) k2 and cyt-Y2 Mdh1-n (Ames 2) y20 (Ames 2)/Mdh1-n (Ames 2) y20 (Ames 2) are conditional lethals. These genotypes are lethal under field conditions, but plants survive in reduced light under shadecloth in the glasshouse. We do not know if their interaction with cyt-Y2 is due to Mdh1-n, y20, or Mdh1-n y20. The reciprocal cross (cyt-Y2 as male parent) gives viable genotypes. These conditional lethal genotypes should be useful for studies on the interaction between organelle and nuclear genomes.This is journal paper no. J-14777 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA 50011-1010. Project 2985 相似文献
7.
The Mus musculus domesticus Tdy allele acts later than the Mus musculus musculus Tdy allele: a basis for XY sex-reversal in C57BL/6-YPOS mice. 总被引:3,自引:0,他引:3
Consomic C57BL/6 males, carrying either the Mus musculus musculus-derived C57BL/6 Y chromosome or the Mus musculus domesticus-derived Poschiavinus Y chromosome, were outcrossed to females of the inbred strains C3H/Bi and CXBH/By and to females of the random bred strain MF1/Ola. In a study at 12.5 days post coitum, gonads of XYC57 and XYPOS fetuses were assessed for the presence of testicular cords. It was found that XYPOS fetuses had a later onset of testicular development than XYC57 fetuses. Limb development, which was monitored as a measure of overall development, was unaffected by the strain of Y present. These data were supported by a longitudinal study in which the increased growth rate of the testes relative to undifferentiated gonads, was also shown to be delayed in XYPOS fetuses. The extent of the delay was estimated to be approximately 14 h. It is concluded that this delay in the onset of testicular differentiation must be caused by differences between the two Y-chromosome types, most probably allelic differences in the testis determinant Tdy. 相似文献
8.
The combined effects of endurance run training and renal hypertension on cytosolic Ca2+ concentration ([Ca2+]c) dynamics and Na+-dependent Ca2+ regulation in rat left ventricular cardiomyocytes were examined. Male Fischer 344 rats underwent stenosis of the left renal artery [hypertensive (Ht), n = 18] or a sham operation [normotensive (Nt), n = 20]. One-half of the rats from each group were treadmill trained for >16 wk. Cardiomyocyte fura 2 fluorescence ratio transients were recorded for 7 min during electrical pacing at 0.5 Hz, 2 mM extracellular Ca2+ concentration, and 29 degrees C. The rate of [Ca2+]c decline was not changed by run training in the Nt group but was reduced in the Ht group. At 7 min, cardiomyocytes were exposed to 10 mM caffeine in the absence of Na+ and Ca2+, which triggered sarcoplasmic reticular Ca2+ release and suppressed Ca2+ efflux via Na+/Ca2+ exchanger. External Na+ was then added, and Na+-dependent Ca2+ efflux rate was recorded. Treadmill training significantly enhanced Na+-dependent Ca2+ efflux rate under these conditions in the Nt group but not in the Ht group. These data provide evidence that renal hypertension prevents the normal run training-induced modifications in diastolic [Ca2+]c regulation mechanisms, including Na+/Ca2+ exchanger. 相似文献
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The environmental texture hypothesis (ETH) proposes that the spatial geometry or texture of the environment influences the
rate at which species are accumulated in space or time. Specifically, the ETH suggests that regions, and spatial scales, that
exhibit a larger rate of environmental distance decay (DD) should exhibit more rapid rates of species turnover. The ETH should
apply over any range of scales where the environment is driving species distributions. To examine the relevance of the ETH
at local spatial scales, we tested for a positive relationship between the rate of change in soil chemical properties and
vascular plant species composition in grassland and woodland habitats. We recorded presence–absence data along a 1.883 km
transect in each habitat and estimated the rate of turnover and environmental DD for spatial lags of 1–41 m. We found that
the soil environment explained spatial patterns of species composition more accurately in the grassland habitat compared to
the woodland habitat. Consequently the rate of change in soil properties as a function of spatial distance was significantly
positively correlated with the rate of species turnover in the grassland but not the woodland. Our study suggests that one
of the central premises of the ETH is relevant for local patterns of species turnover if the environment appears to influence
species composition. 相似文献