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71.
Estimation of gene number in mammals is difficult due to the high proportion of noncoding DNA within the nucleus. In this study, we provide a direct measurement of the number of genes in human and mouse. We have taken advantage of the fact that many mammalian genes are associated with CpG islands whose distinctive properties allow their physical separation from bulk DNA. Our results suggest that there are approximately 45,000 CpG islands per haploid genome in humans and 37,000 in the mouse. Sequence comparison confirms that about 20% of the human CpG islands are absent from the homologous mouse genes. Analysis of a selection of genes suggests that both human and mouse are losing CpG islands over evolutionary time due to de novo methylation in the germ line followed by CpG loss through mutation. This process appears to be more rapid in rodents. Combining the number of CpG islands with the proportion of island-associated genes, we estimate that the total number of genes per haploid genome is approximately 80,000 in both organisms. 相似文献
72.
The association between hereditary motor and sensory neuropathy (HMSN) and optic atrophy has been termed HMSN type VI. The autosomal dominant inheritance of this syndrome is reported. Three generations were affected with optic atrophy, which differed in some respects from classic dominant optic atrophy, and an asymptomatic, mainly sensory, neuropathy. 相似文献
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The Rose-of-Sharon,Hibiscus syriacus (L.), can be a significant alternate host plant for the boll weevil,Anthonomus gradis (Boh.). Boll weevils are known to be deterred from feeding and ovipositing in the buds unless the calyx is removed. This investigation was initiated to identify calyx allelochemicals that deter feeding with the eventual strategy of breeding for cotton lines high in these allelochemicals in the appropriate tissues. The feeding deterrency of calyx tissue from the buds of Rose-of-Sharon for the boll weevil was confirmed. The most active deterrent fraction was found to contain mostly fatty acids and their methyl esters. Saturated fatty acids and their methyl esters were generally found to be stimulatory, while the unsaturated species were found to be deterrent. Higher quantities of the fatty acids, particularly the unsaturated species, were found in Rose-of-Sharon calyx tissue than in the buds without calyx. This supports the hypothesis developed through the isolational work and testing of standards that the unsaturated fatty acids are significant deterrents of boll weevil feeding.Coleoptera: Curculionidae.Malvales: Malvaceae.Mention of a commercial or proprietary product in this paper does not constitute endorsement of this product by Delta State University or USDA. 相似文献
76.
A brief history is given of antenna research and development at the Commonwealth Scientific and Industrial Research Organization (CSIRO) Division of Radiophysics. It covers wartime radar (1939-45), radio astronomy (1945-76), reflector-feed R&D (1963 to present), a microwave landing system (1971-83), the Australia telescope (1982-90), and satellite communications (1977 to present). Antenna measurement facilities and current projects are briefly described 相似文献
77.
S. John Pirt Susan M. A. Pickett Andrew M. Pickett Erick J. Vandamme Clive W. Bird 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1981,31(1):167-177
A new streptomyces strain, designated Streptomyces elizabethii, was isolated from a soil sample using a method which selected antifungal antibiotic producers. S. elizabethii produces an antifungal polyene (elizabethin) and antibacterial actinomycins. Optimal conditions were elucidated for sporulation of the streptomycete in bottle cultures and for polyene production in shake flask cultures. High sugar concentrations were found to repress actinomycin biosynthesis and increase polyene production. Excess potassium phosphate inhibited polyene production. 相似文献
78.
Two data sets are presented that were generated with a rigorous radiative transfer code. One data set is an AM1.5 direct normal spectrum, and the other data set is an AM1.5 global spectrum on a surface tilted 37° from the horizontal towards the sun. These data are updates to data that are nearing acceptance as standards of the American Society of Testing and Materials. An improved extraterrestrial spectrum and other refinements were made to improve the accuracy of these data sets. A preliminary comparison between modeled and measured data is shown, which supports the accuracy of the data sets. 相似文献
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The elevation of intracellular levels of cyclic AMP by forskolin stimulation of adenylate cyclase regulates early and late phase neutrophil responses differentially. Early phase neutrophil responses as measured by shape change in response to chemotactic factors, transmigration across a polycarbonate membrane and priming were unaffected by forskolin-induced elevation of intracellular cAMP. Late phase neutrophil responses such as release of superoxide anions, activation of phospholipase A2 and platelet activating factor (PAF) synthesis were inhibited by increasing intracellular cAMP through the addition of 10 microM forskolin for 10 min prior to stimulation. N-Formyl-methionyl-leucyl-phenylalanine-stimulated arachidonic acid release fell from 9.3% (untreated cells) to 4.6% in forskolin-treated cells. PAF generation was also inhibited from 430 pg/10(6) cells in untreated cells to background levels in forskolin-treated cells (110 pg/10(6) cells). Also, the reduction of cytochrome c by superoxide anions fell from 4.2 nmol/10(6) cells in the absence of forskolin to 2.0 nmol/10(6) cells following forskolin treatment. These results indicate that in neutrophils the elevation of cAMP acts differentially on cellular responses, not affecting early activation events, but markedly inhibiting late events such as the release of inflammatory mediators. 相似文献