首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
3.
Genetic deficiency of the alpha-gamma-subunit of the eighth complement component (C8 alpha-gamma) was found in a strain of the New Zealand White rabbit. The serum of this deficient rabbit lacked the immunochemical and functional alpha-gamma-subunit of C8. Mating tests indicate that the C8 alpha-gamma deficiency is transmitted as a simple autosomal recessive trait with the following physiologic characteristics. The body weight at the first week of life, mature weight, and litter size of the deficient animals were smaller than those of heterozygous and normal ones. In addition, survival rates for the first 3 mo of life of the deficient animals tended to be lower than those of heterozygous and normal littermates.  相似文献   

4.
Landscape-scale approaches to conservation stem largely from the classic ideas of reserve design: encouraging bigger and more sites, enhancing connectivity among sites, and improving habitat quality. Trade-offs are imposed between these four strategies by the limited resources and opportunities available for conservation programmes, including the establishment and management of protected areas, and wildlife-friendly farming and forestry. Although debate regarding trade-offs between the size, number, connectivity and quality of protected areas was prevalent in the 1970–1990s, the implications of the same trade-offs for ongoing conservation responses to threats from accelerating environmental change have rarely been addressed. Here, we reassess the implications of reserve design theory for landscape-scale conservation, and present a blueprint to help practitioners to prioritise among the four strategies. We consider the new perspectives placed on landscape-scale conservation programmes by twenty-first century pressures including climate change, invasive species and the need to marry food security with biodiversity conservation. A framework of the situations under which available theory and evidence recommend that each of the four strategies be prioritized is provided, seeking to increase the clarity required for urgent conservation decision-making.  相似文献   

5.
A random sample from the endogamic population of Greek Sarakatsans has been studied for eight blood groups, eleven enzymic genetic systems and haemoglobin variants. The allelic frequencies of the polymorphic loci have been compared with those of other samples from the Greek mainland and other European populations. The Sarakatsans tend to resemble their neighbours. The comparison with European populations indicates that the Sarakatsans have gene frequencies similar to other Mediterranean and European populations. However, the monomorphism of the Kell system, the low frequency of the ACP*B, AK*1 and GLO*1 allelas and the high frequency of the ACP*C, ESD*1 and GPT*1 alleles, are some of the distinguishing features of Sarakatsans. Furthermore, the Sarakatsans are not a high risk population for G6PD deficiency and haemoglobinopathies.  相似文献   

6.
7.
Genetic modification of animals in the next century   总被引:2,自引:0,他引:2  
Murray JD 《Theriogenology》1999,51(1):149-159
Since the initial demonstration in 1982 of profound phenotypic effects stemming from the expression of a single transgene, genetic engineering has revolutionized fundamental biological and biomedical research. The application of transgenic technology to farm animals has held the promise of being able to improve animal agriculture significantly and has resulted in a new industry, i.e., the successful expression of foreign proteins in the mammary gland for the pharmaceutical industry. Work over the last few years in model species (e.g., the mouse) and new technical developments such as cloning have now set the stage for the initial application of transgenic technology for the improvement of farm animals. Major limitations that remain are the lack understanding of which genes we should transfer in order to alter quantitative production traits usefully and the low efficiency of producting transgenic founders. Furthermore, more research is needed concerning the consequences and potential problems arising from the integration of transgenes into populations with varying genetic backgrounds. Recent advances suggest that within the first decade of the 21 st century the first transgenic animals will become available to the livestock industry, with acceptance depending upon their cost versus their potential economic benefit to the producers.  相似文献   

8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号