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151.
Summary Surgical bursectomy in chicken at 62 h of incubation produces a delay in skin allograft rejection, whereas later bursectomized chickens show normal rejection time. It is proposed that the Bursa of Fabricius in early stages of development influences the development of cellular immunity.The authors are indebted to Miss Nelly Pérez Jimeno for her invaluable technical assistance. 相似文献
152.
Additive threats from pathogens, climate and land-use change for global amphibian diversity 总被引:1,自引:0,他引:1
Amphibian population declines far exceed those of other vertebrate groups, with 30% of all species listed as threatened by the International Union for Conservation of Nature. The causes of these declines are a matter of continued research, but probably include climate change, land-use change and spread of the pathogenic fungal disease chytridiomycosis. Here we assess the spatial distribution and interactions of these primary threats in relation to the global distribution of amphibian species. We show that the greatest proportions of species negatively affected by climate change are projected to be found in Africa, parts of northern South America and the Andes. Regions with the highest projected impact of land-use and climate change coincide, but there is little spatial overlap with regions highly threatened by the fungal disease. Overall, the areas harbouring the richest amphibian faunas are disproportionately more affected by one or multiple threat factors than areas with low richness. Amphibian declines are likely to accelerate in the twenty-first century, because multiple drivers of extinction could jeopardize their populations more than previous, mono-causal, assessments have suggested. 相似文献
153.
Erwin Knecht Carmen Aguado Jaime Cárcel Inmaculada Esteban Juan Miguel Esteve Ghita Ghislat José Félix Moruno José Manuel Vidal Rosana Sáez 《Cellular and molecular life sciences : CMLS》2009,66(15):2427-2443
In higher organisms, dietary proteins are broken down into amino acids within the digestive tract but outside the cells, which
incorporate the resulting amino acids into their metabolism. However, under certain conditions, an organism loses more nitrogen
than is assimilated in the diet. This additional loss was found in the past century to come from intracellular proteins and
started an intensive research that produced an enormous expansion of the field and a dispersed literature. Therefore, our
purpose is to provide an updated summary of the current knowledge on the proteolytic machinery involved in intracellular protein
degradation and its physiological and pathological relevance, especially addressed to newcomers in the field who may find
further details in more specialized reviews. However, even providing a general overview, this is an extremely wide field and,
therefore, we mainly focus on mammalian cells, while other cells will be mentioned only for comparison purposes. 相似文献
154.
Endoglin regulates mural cell adhesion in the circulatory system 总被引:1,自引:1,他引:0