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21.
22.
Tom Müller 《Biodiversity and Conservation》1994,3(2):116-125
The need to integratein situ conservation into the planning process is outlined, and the importance of vegetation survey to determine conservation priorities and to identify areas suitable forin situ conservation is stressed. A case is presented, drawing on experience gained in Zimbabwe, of how a botanical institute can become an integral part of biological conservation. The institute should consist of a herbarium, a botanical garden, a gene bank and a vegetation survey unit. The function of each section, how they interlink, and how they can be integrated are discussed. 相似文献
23.
Alicia P. Higueruelo Adrian Schreyer G. Richard J Bickerton Tom L. Blundell Will R. Pitt 《PloS one》2012,7(12)
Efforts to increase affinity in the design of new therapeutic molecules have tended to lead to greater lipophilicity, a factor that is generally agreed to be contributing to the low success rate of new drug candidates. Our aim is to provide a structural perspective to the study of lipophilic efficiency and to compare molecular interactions created over evolutionary time with those designed by humans. We show that natural complexes typically engage in more polar contacts than synthetic molecules bound to proteins. The synthetic molecules also have a higher proportion of unmatched heteroatoms at the interface than the natural sets. These observations suggest that there are lessons to be learnt from Nature, which could help us to improve the characteristics of man-made molecules. In particular, it is possible to increase the density of polar contacts without increasing lipophilicity and this is best achieved early in discovery while molecules remain relatively small. 相似文献
24.
Douglas G. Gilmour Walter M. Collins Tom L. Fredericksen Willard E. Urban Jr. Paul F. Ward Nancy L. DiFronzo 《Immunogenetics》1986,23(1):1-6
Chickens of Regional Poultry Research Laboratory (RPRL) inbred line 63 regress sarcomas induced by Bryan high-titer Rous sarcoma virus to a greater extent than chickens of line RPRL 100, although these lines are identical for the major histocompatibility B complex. They differ, however, at three independent autosomal loci: Ly-4 and Th-1 determine the surface alloantigens of partly overlapping subsets of T lymphocytes, and Bu-1 determines a surface alloantigen of B lymphocytes. The association of genotypes at these loci with quantitative variation in their ability to regress Rous sarcomas was tested in segregating F4 generation progeny derived from crosses of lines 100 and 63. The Ly-4 and Bu-1 genotypes showed association with Rous sarcoma regression, but the Th-1 genotype did not. Chickens of the Ly-4
a/Ly-4
a, Bu-1
b/Bu-1
b and Ly-4
b/Ly-4
b, Bu-1
a/Bu-1
a genotypes had a significantly higher regressor ability than the other two double homozygous genotypes. These results indicate that higher regression is associated with (1) interaction between the Ly-4 and Bu-1 loci, and (2) complementation between either the line 6 Ly-4
a allele and the line 100 Bu-1
b allele, or the line 100 Ly-4
b allele and the line 6 Bu-1
a allele. 相似文献
25.
The structure of the actin-myosin head complex during the ATPase cycle has been studied by electron microscopy of negatively stained acto-heavy-meromyosin. In the absence of ATP, heavy meromyosin molecules generally showed a regular, angled appearance, with both heads attached to the actin filament. In the presence of ATP, attached molecules showed a less ordered structure, often with only one head attached. We conclude that configurations other than the rigor structure occur during the actomyosin cross-bridge cycle. 相似文献
26.
27.
28.
Craig R. Allen Ahjond S. Garmestani Jill A. LaBram Amanda E. Peck Luanna B. Prevost 《Biological invasions》2006,8(2):169-176
Woodlots are forest islands embedded within an urban matrix, and often represent the only natural areas remaining in suburban
areas. Woodlots represent critical conservation areas for native plants, and are important habitat for wildlife in urban areas.
Invasion by non-indigenous (NIS) plants can alter ecological structure and function, and may be especially severe in remnant
forests where NIS propagule pressure is high. Woody shrubs in the Family Berberidaceae have been well documented as invaders
of the forest–urban matrix in North America. Mahonia bealei (Berberidaceae) is a clonal shrub native to China, and is a popular ornamental in the Southeastern United States. Mahoni bealei is listed as “present” on some local and state floras, but almost nothing is known regarding its invasion potential in the
United States. We sampled 15 woodlots in Clemson, South Carolina, to assess the invasion of M. bealei and other woody non-indigenous species (NIS). M. bealei invaded 87% of the woodlots surveyed and species richness of NIS on these woodlots varied from 5 to 14. Stepwise-multiple
regression indicated that less canopy cover and older M. bealei predicted greater abundance of M. bealei , and that not all subdivisions were equally invaded (P < 0.0001; r2 = 0.88). The impact of M. bealei on native flora and fauna may be considerable, and it is likely to continue to spread in the Southeastern United States.
M. bealei should be recognized as an aggressive invader in the Southeastern United States, with the potential for negative impacts
on native flora and fauna. 相似文献
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30.
Summary Cellular fatty acids inLactobacillus büchneri were transmethylated with H2SO4 catalyst in methanol at elevated temperature. By optimising the reaction time and the amounts of catalyst and methanol used at a fixed temperature it was possible to maximise the lactobacillic acid yield. The yield of lactobacillic acid with this method was better than with the traditional method using base-catalysed saponification followed by HCL-catalysed methylation. 相似文献