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61.
OBSERVATIONS ON THE SWOLLEN LATERAL ROOTS OF THE CYPERACEAE 总被引:5,自引:1,他引:5
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Protein contents and glutamate: glyoxylate, serine: glyoxylate,alanine: glyoxylate and glutamate: pyruvate aminotransferaseactivities per gram fresh weight declined sharply when Lemnaminor L., previously grown on nitrate medium, was starved ofnitrogen. Nitrogen replenishment after 5 d caused complete recoveryof these parameters with higher values in ammonium-fed thannitrate-fed plants 7 d after transfer of plants from nitrogen-freemedium. Glutamate: glyoxylate and alanine: glyoxylate aminotransferasespecific activities (based on total extracted protein) showedlittle change with nitrogen availability. Serine: glyoxylateaminotransferase increased slowly during nitrogen starvationand decreased following nitrogen replenishment whether withammonium or nitrate. After 1 d of nitrogen starvation the specificactivity of glutamate: pyruvate aminotransferase declined; itincreased following nitrogen replenishment and ammonium gaverise to agreater activity than nitrate. The results are discussed in relation to the differences instability of the various enzymes relative to the overall proteinturnover rate. Key words: Aminotransferases, Nitrogen source, Photorespiration 相似文献
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JOHN A. WIENS 《Ibis》1995,137(S1):S97-S104
Fragments of habitat are often viewed as islands and are managed as such; however, habitat fragmentation includes a wide range of spatial patterns of environments that may occur on many spatial scales. Fragments exist in a complex landscape mosaic, and dynamics within a fragment are affected by external factors that vary as the mosaic structure changes. The simple analogy of fragments to islands, therefore, is unsatisfactory. Understanding how birds respond to these complexities of fragmentation requires mechanistic studies focused on habitat selection and movement behaviour. Conservation efforts must be based on viewing fragmentation as a range of conditions that occurs in a landscape mosaic, and management should be directed toward the mosaics rather than focusing solely on reserves. 相似文献
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JOHN H. HAYDEN HOWARD ROTHSTEIN 《Differentiation; research in biological diversity》1979,15(1-3):153-160
Three weeks after hypophysectomy mitosis and DNA synthesis are absent in the lens of the leopard frog ( Rana pipiens ). By labeling germinative zone cells in their last DNA synthetic period we were able to follow them in the absence of further proliferation. By this means it has been demonstrated that migration of epithelial cells to the equator of the lens is stopped. Based on indirect measurements it seems that lens fiber formation also ceases. A correlation coefficient of 0.86 was computed between average labeling index and average distance migrated. In hypophysectomized animals the correlation coefficient between time and migration was 0.02 while in intact animals it is 0.87. 相似文献
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CHRIS EIPPER 《The Australian journal of anthropology》1985,15(3):203-213
Double-bind theory is applied to the concept of hegemony in this paper in order to analyse the dependency of a small community (Bantry Bay in Ireland) upon a multinational corporation (Gulf Oil). The implications for state policy of this relationship are then considered. The argument is that the dispensation of development as patronage in the form of industrial projects provided to needy communities puts such communities in an invidious predicament. The result is that they become ambivalent advocates of the interests of multinationals in the defence of their own. 相似文献
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FEDERICA G. PANNACCIULLI SANIT PIYAPATTANAKORN JOHN D. D. BISHOP STEPHEN J. HAWKINS NORMAN MACLEAN 《Molecular ecology resources》2005,5(3):641-643
This study reports the isolation and characterization of seven highly polymorphic microsatellite loci in Chthamalus montagui (Crustacea, Cirripedia). The loci were isolated from a library constructed from genomic DNA enriched for CA repeats. The markers yielded three to 43 alleles per locus (mean 16.7) in samples averaging 49 individuals. Observed heterozygosity ranged from 0.08 to 0.58 (mean 0.39). These microsatellite loci will be valuable tools for population genetic studies of this species. 相似文献