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N C Rawlings I J Churchill W D Currie I B Joseph 《Journal of reproduction and fertility》1991,93(1):1-7
Stimulation by naloxone, an opioid antagonist, of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion was examined in spring-born crossbred ram lambs raised under natural photoperiod. Vehicle (n = 6) or 1 mg naloxone/kg vehicle (n = 6) was injected (i.m.) 3 times at 2-h intervals at 5, 10 and 15 weeks of age and 4 times at 2-h intervals at 20, 25, 30 and 35 weeks of age. Blood samples were taken every 12 min for 6 h at 5, 10 and 15 weeks of age and for 8 h at 20, 25, 30 and 35 weeks of age. Naloxone had no effect on age at sexual maturity (controls 239 +/- 23 days; naloxone 232 +/- 33 days). The only significant (P less than 0.05) effect of naloxone on FSH was a greater pulse amplitude in 10-week-old treated lambs than in control lambs. Naloxone treatment resulted in greater LH pulse amplitude at 5 and 10 weeks of age (P less than 0.05), lower basal serum concentration of LH at 10 weeks of age (P less than 0.05), greater LH pulse frequency at 25 weeks of age (P less than 0.05), and greater mean serum concentrations of LH, basal LH and LH pulse amplitude at 35 weeks of age (P less than 0.01) than in the controls. In both groups of lambs, mean and basal FSH, and LH and FSH pulse amplitude were highest at 5 weeks of age and fell with age. LH pulse amplitude was lowest at 35 weeks of age (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Ovarian tissues were obtained from cyclic goats during the early, mid and late breeding season. Immunoreactive oxytocin was measured by RIA in tissue extracts after chromatography on octadecylsilica cartridges. Luteal oxytocin concentrations were significantly greater during the early breeding season than during the mid or late breeding season. Oxytocin is luteolytic in goats. High concentrations of luteal oxytocin may be related to the high incidence of short estrus at the onset of the breeding season. 相似文献
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A rapid sensitive method for the detection of viable bacterial cells is described in which P32 as inorganic orthophosphate is used to label the cells. Factors affecting the uptake of P32 by cells as well as the sensitivity of the method have been explored with suspensions of Aerobacter aerogenes. The uptake of P32O4 is dependent on several factors. Of various incubation media tested, one composed of 0.005 m KCl, 0.002 m MgSO4 and 10 mg/ml of glucose was found to best stimulate the uptake of the tracer. Incubation time and temperature and level of isotope and of unlabeled P also affected uptake. Labeled cells were collected on a membrane filter for measurement of radioactivity. Under optimal conditions, as few as 23 viable cells per milliliter were detected in 1 hr with 95% confidence. 相似文献
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Intragenic Dominant Suppressors of Glp-1, a Gene Essential for Cell-Signaling in Caenorhabditis Elegans, Support a Role for Cdc10/Sw16/Ankyrin Motifs in Glp-1 Function
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The glp-1 gene product mediates cell-cell interactions required for cell fate specification during development in Caenorhabditis elegans. To identify genes that interact with glp-1, we screened for dominant suppressors of two temperature-sensitive glp-1 alleles and recovered 18 mutations that suppress both germline and embryonic glp-1 phenotypes. These dominant suppressors are tightly linked to glp-1 and do not bypass the requirement for a distal tip cell, which is thought to be the source of a signal that is received and transduced by the GLP-1 protein. Using single-strand conformation polymorphism (SSCP) analysis and DNA sequencing, we found that at least 17 suppressors are second-site intragenic revertants. The suppressors, like the original glp-1(ts) mutations, are all located in the cdc10/SWI6/ankyrin domain of GLP-1. cdc10/SWI6/ankyrin motifs have been shown to mediate specific protein-protein interactions in other polypeptides. We propose that the glp-1(ts) mutations disrupt contact between GLP-1 and an as yet unidentified target protein(s) and that the dominant suppressor mutations restore appropriate protein-protein interactions. 相似文献