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81.
K. J. Kasha N. C. Subrahmanyam A. Ali 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1978,51(4):169-175
Summary Haploids from Hordeum vulgare (2n = 14) X H. Bulbosum (2n = 14) crosses result after fertilization from the subsequent elimination of bulbosum chromosomes during early embryo development. Seed set from the cross is high but embryo culture is necessary to obtain seedlings. Application of gibberellin A3 (GA3) to pollinated florets was effective for increasing the frequency of haploid seedlings produced on both nutrient-fed detached tillers and intact plants. GA3 increased both seed set and embryo yield. The number of cells per embryo during its transition to the haploid state was increased two to three times following GA3 treatments. Enhanced embryo and endosperm development was attributed to increased mitotic activity. The number of visibly differentiated embryos was doubled to about 35 % of the cultured embryos after GA3 was applied to detached tillers in nutrient solution. About 70 % of the resulting haploid plants developed from the visibly differentiated embryos. The detached tiller technique offers a convenient method of culturing haploids from field-grown plants. 相似文献
82.
l-threo-2,3-Hexodiulosono-1,4-lactone 2-(arylhydrazones) (2) were prepared by condensation of dehydro-l-ascorbic acid with various arylhydrazines. Reaction of 2 with hydroxylamine gave the 2-(arylhydrazone) 3-oximes (3). On boiling with acetic anhydride, 3 gave 2-aryl-4-(2,3-di-O-acetyl-l-threo-glycerol-l-yl)-1,2,3-triazole-5-carboxylic acid 5,41-lactones (4). On treatment of 4 with liquid ammonia, 2-aryl-4-(l-threo-glycerol-l-yl)-1,2,3-triazole-5-carboxamides (5) were obtained. Acetylation of 5 with acetic anhydride-pyridine gave the triacetates, and vigorous acetylation with boiling acetic anhydride gave the tetraacetyl derivatives. Periodate oxidation of 5 gave the 2-aryl-4-formyl-1,2,3-triazole-5-carboxamides (8), and, on reduction, 8 gave the 2-aryl-4-(hydroxymethyl)-1,2,3-triazole-5-carboxamides, characterized as the monoacetates and diacetates. Controlled reaction of 2 with sodium hydroxide, followed by neutralization, gave 3-(l-threo-glycerol-l-yl)-4,5-isoxazolinedione 4-(arylhydrazones), characterized by their triacetates. Reaction of 2 with HBr-HOAc gave 5-O-acetyl-6-bromo-6-deoxy-l-threo-2,3-hexodiulosono-1,4-lactone 2-(arylhydrazones); these were converted into 4-(2-O-acetyl-3-bromo-3-deoxy-l-threo-glycerol-l-yl)-2-aryl-1,2,3-triazole-5-carboxylic acid 5,41-lactones on treatment with acetic anhydride-pyridine. 相似文献
83.
Christophe Biju-Duval Hajer Ennafaa Nicole Dennebouy Monique Monnerot Françoise Mignotte Ramon C. Soriguer Amel El Gaaïed Ali El Hili Jean-Claude Mounolou 《Journal of molecular evolution》1991,33(1):92-102
Summary A characterization was conducted on mitochondrial DNA (mtDNA) molecules extracted separately from 107 European rabbits (Oryctolagus cuniculus) both wild and domestic, 13 European hares (Lepus capensis), and 1 eastern cottontail (Sylvilagus floridanus). Experimentally this study took into account restriction site polymorphism, overall length variation of the noncoding region, and numbers of repeated sequences. Nucleotide divergences indicate that the mtDNAs from the three species derived from a common ancestor some 6–8 million years (Myr) ago. Every animal appeared heteroplasmic for a set of molecules with various lengths of the noncoding region and variable numbers of repeated sequences that contribute to them. This systematic heteroplasmy, most probably generated by a rate of localized mtDNA rearrangements high enough to counterbalance the cellular segregation of rearranged molecules, is a shared derived character of leporids.The geographic distribution of mtDNA polymorphism among wild rabbit populations over the western European basin shows that two molecular lineages are represented, one in southern Spain, the second over northern Spain, France, and Tunisia. These two lineages derived from a common ancestor some 2 Myr ago. Their present geographical distribution may be correlated to the separation of rabbits into two stocks at the time of Mindel glaciation.Finally the distribution of mtDNA diversity exhibits a mosaic pattern both at inter- and intrapopulation levels. 相似文献
84.
Extraction of whole lobes of normal rat liver with dimethyl sulphoxide (DMSO) under N2 gives extracts which contain 5—10 μmol/l·O?2 (50-100 nmol·O?2 per 10 ml extract per 4 g liver; 1.25-2.50 nmol·O?2 per millilitre per gram liver). Evidence for ·O?2 in the extracts is given by: (1) electron spin resonance signals (ESR), (2) differential pulse polarography (DPP), (3) chemiluminescence (CL), and (4) nitroblue tetrazolium reduction (NBT). All tests yield results identical with those obtained with authentic ·O?2. Extraction of ·O?2 is enhanced by tetrabutyl ammonium ion, and is maximal at 1-3 min. These results raise the possibility that substantial amounts of ·O?2 are normally sequestered in protective membranous sites in vivo. 相似文献
85.
A microtiter plate-based enzyme immunoassay has been developed for phaseolinone, a phytotoxin isolated from the culture filtrate of the plant-pathogenic fungus Macrophomina phaseolina (Tassi) Goid. The smallest amount of phaseolinone detectable by the method is 5 pg per well. The method is validated by comparison with high-performance liquid chromatography and used to confirm and estimate phaseolinone production in seeds infected with the fungus. The degree of seed inhibition correlated well with the amount of toxin produced in infected seeds, 50% inhibition being observed at a toxin concentration of 0.60 micrograms/g of wet tissue. 相似文献
86.
Detection of Vibrio cholerae O1 in the aquatic environment by fluorescent-monoclonal antibody and culture methods. 总被引:8,自引:6,他引:2
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A Huq R R Colwell R Rahman A Ali M A Chowdhury S Parveen D A Sack E Russek-Cohen 《Applied microbiology》1990,56(8):2370-2373
Vibrio cholerae O1 in plankton samples collected from ponds and rivers between February 1987 and January 1990 in Matlab, Bangladesh, was detected by the fluorescent-monoclonal antibody (FA) technique. Samples were collected at sites which were monitored fortnightly (fixed sites) as well as at sites that were part of a case-control study. FA results were compared with those obtained by conventional culture methods (CM). A total of 876 samples were collected; V. cholerae O1 was detected in 563 samples (64.27%) by the FA method and in 3 samples (0.34%) by CM. Of the fixed-site plankton samples, 439 (63.62%) were positive by FA and none were positive by CM. Of the 93 case sites sampled on the day after the occurrence of a case of cholera, 73 (78.49%) were positive for V. cholerae O1 by FA and 3 (3.2%) were positive by CM. In comparison, of the 93 first-day sample collections at control sites at the time a case of cholera occurred, only 51 (54.83%) were positive by FA and none were positive by CM. From the data, it is concluded that V. cholerae O1 is present throughout the year in the ponds and rivers of Bangladesh that were examined in this study and that V. cholerae can be detected by FA but not always by CM. The FA procedure was found to be very useful in detecting V. cholerae in plankton, with which it was associated and often occurred in large numbers in the nonculturable stage. Thus, studies investigating the significance of the role of environmental factors in the epidemiology of cholera can be performed effectively by using FA. Such studies are in progress. 相似文献
87.
A new class of therapeutic agents, sharing inhibition of the slow calcium channel, will soon be available to the American patient. Selective action of these agents upon the atrioventricular node, the smooth muscle of coronary and peripheral arteries, and the contractility of cardiac muscle opens new vistas in cardiovascular pharmacology. Early release of these agents by the Federal Drug Administration for general use is urged, based upon the already wide and successful experience in the European and South American continents. 相似文献
88.
Bovine gastric mucosal and muscle microsomes synthesize prostaglandins and thromboxane B2 (TXB2) from arachidonic acid (AA). TXB2 and 6-keto-prostaglandin F1α (6-keto-PGF1α) were the major products synthesized by pylorus, body, and cardiac region of the gastric mucosa. Gastric muscle mainly synthesized 6-keto-PGF1α. TXB2 and 6-keto-PGF1α synthesis occurs at an appreciable rate from endogenous precursors but more rapidly with added arachidonate. Prostaglandins E2, F2α and D2 were synthesized in smaller amounts under the conditions studied. 相似文献
89.
90.
Ali E. Engin Richard D. Peindl Vasundara V. Varadan Vijay K. Varadan 《Journal of biomechanics》1980,13(12):1053-1059
This investigation is concerned with a scattering matrix approach which is proposed for the non-destructive, differential diagnosis of muscle diseases. A number of muscle diseases are classified according to their various pathological indications and appropriate material parameters are derived for utilization as input data for a theoretical model. In the mathematical analysis phase of the model, Waterman's T-matrix approach in conjunction with statistical averaging for both position and orientation of muscle fibers are employed to obtain the attenuation due to geometric dispersion for a wide range of frequencies. The numerical results not only exhibit qualitative agreement with existing experimental data for normal muscle but also display differentiable patterns for the various muscle disease cases. The formulation is an improvement over the previously applied scattering theory in that it obtains the attenuation over a continuous frequency spectrum. 相似文献