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A centrifugation binding assay has been used to demonstrate the binding of [3H] (±) abscisic acid to membrane-rich fractions prepared from leaves of Vicia faba L. Kinetic analysis of this binding shows evidence of saturation of binding sites with increasing concentration of ligand. Scatchard analysis of these data yields a biphasic plot possibly indicating the presence of two types of binding sites. The dissocation constant for the high affinity site has been calculated to be 3.5×10-8 mol 1-1. 相似文献
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Interspecific plant hybridization is a common and evolutionarily important phenomenon. Here, the results of a study of hybridization in the Florida Keys between two species of sea oxeye daisy, Borrichia frutescens and B. arborescens, are reported. Nuclear and chloroplast genetic loci, log-likelihood assignment tests, and maximum likelihood estimates of genealogical class frequencies were used to identify hybrid and parent genotypes, to investigate the utility of leaf and flower morphology for hybrid identification, and to study symmetry and degree of introgression between the species. Genetic analyses confirmed the identity of the hybrid and parent plants that were used for the morphological studies. Together, leaf and flower morphology can be used to identify hybrid and parental types with moderate accuracy (4% error rate). Population genetic analyses indicate that, in spite of a significant level of hybridization, pure B. frutescens and B. arborescens are persisting in the hybrid zone. Of the nonparentals, about 18% appear to be F(1) hybrids, over 50% F(2) hybrids, and the remainder backcrossed individuals but only with the B. frutescens parent. It is postulated that the hybrid zone in the Florida Keys is being maintained by a combination of positive assortative mating and clonal reproduction. 相似文献
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L. R. I. Baker P. Ackrill W. R. Cattell T. C. B. Stamp L. Watson 《BMJ (Clinical research ed.)》1974,3(5924):150
In a patient receiving regular dialysis prolonged hypophosphataemia due to aluminium hydroxide therapy resulted in osteomalacia and severe proximal myopathy. Both osteomalacia and myopathy responded to correction of hypophosphataemia without vitamin D therapy. 相似文献
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S E Banner S J Wood R H Osborne K J Cattell 《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1990,95(2):233-236
1. Octopamine (OA) (10(-7)-10(-5) M) relaxed isolated foreguts. Tyramine mimicked the effects of OA but was 64x less potent. 2. Proctolin (10(-8) M to 10(-6) M) induced contraction of isolated foreguts was antagonised non competitively by tyramine. 3. Mianserin (10(-6) M) was a non competitive antagonist of relaxation caused by tyramine but was without effect on proctolin induced contraction. 4. Caffeine (1 microM and 2 microM) caused non competitive inhibition of proctolin-induced tissue contraction. 5. It is concluded that tyramine antagonises proctolin-induced contraction of the foregut by activating an adenylate cyclase-linked OA2 receptor. 相似文献
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Stewart GS Graham C Cattell S Smith TP Simmons NL Smith CP 《American journal of physiology. Regulatory, integrative and comparative physiology》2005,289(2):R605-R612
The UT-A (SLC14a2) and UT-B (SLC14a1) genes encode a family of specialized urea transporter proteins that regulate urea movement across plasma membranes. In this report, we describe the structure of the bovine UT-B (bUT-B) gene and characterize UT-B expression in bovine rumen. Northern analysis using a full-length bUT-B probe detected a 3.7-kb UT-B signal in rumen. RT-PCR of bovine mRNA revealed the presence of two UT-B splice variants, bUT-B1 and bUT-B2, with bUT-B2 the predominant variant in rumen. Immunoblotting studies of bovine rumen tissue, using an antibody targeted to the NH2-terminus of mouse UT-B, confirmed the presence of 43- to 54-kDa UT-B proteins. Immunolocalization studies showed that UT-B was mainly located on cell plasma membranes in epithelial layers of the bovine rumen. Ussing chamber measurements of ruminal transepithelial transport of (14)C-labeled urea indicated that urea flux was characteristically inhibited by phloretin. We conclude that bUT-B is expressed in the bovine rumen and may function to transport urea into the rumen as part of the ruminant urea nitrogen salvaging process. 相似文献
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Systemic lupus erythematosus (SLE) is a common, potentially fatal, non-organ-specific autoimmune disorder. Immune complex-mediated kidney disease is the major cause of mortality. Apoptotic cells in the epidermis are a possible source of self Ags, and apoptosis of endothelial cells and lymphocytes is thought to contribute to end-organ damage. We have previously shown that female transgenic mice expressing IFN-gamma in the epidermis develop inflammatory skin disease and features of SLE that have striking parallels with the human condition. We have now tested the effects of a pan-caspase inhibitor, carbobenzoxy-valyl-alanyl-aspartyl-(beta-o-methyl)-fluoromethylketone, on disease progression. Daily s.c. administration of carbobenzoxy-valyl-alanyl-aspartyl-(beta-o-methyl)-fluoromethylketone to female transgenic mice over a 3-wk period resulted in significant amelioration of both glomerular and interstitial renal damage, independent of the effects on autoantibody levels or skin inflammation. We propose that apoptosis inhibitors could be beneficial in the treatment of human SLE. 相似文献
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