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11.
Mutations in the gene encoding 11-cis retinol dehydrogenase cause delayed dark adaptation and fundus albipunctatus. 总被引:8,自引:0,他引:8
The metabolic pathways that produce 11-cis retinal are important for vision because this retinoid is the chromophore residing in rhodopsin and the cone opsins. The all-trans retinal that is generated after cone and rod photopigments absorb photons of light is recycled back to 11-cis retinal by the retinal pigment epithelium and Müller cells of the retina. Several of the enzymes involved have recently been purified and molecularly cloned; here we focus on 11-cis retinol dehydrogenase (encoded by the gene RDH5; chromosome 12q13-14; ref. 4), the first cloned enzyme in this pathway. This microsomal enzyme is abundant in the retinal pigment epithelium, where it has been proposed to catalyse the conversion of 11-cis retinol to 11-cis retinal. We evaluated patients with hereditary retinal diseases featuring subretinal spots (retinitis punctata albescens and fundus albipunctatus) and patients with typical dominant or recessive retinitis pigmentosa for mutations in RDH5. Mutations were found only in two unrelated patients, both with fundus albipunctatus; they segregated with disease in the respective families. Recombinant mutant 11-cis retinol dehydrogenases had reduced activity compared with recombinant enzyme with wild-type sequence. Our results suggest that mutant alleles in RDH5 are a cause of fundus albipunctatus, a rare form of stationary night blindness characterized by a delay in the regeneration of cone and rod photopigments. 相似文献
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Although the oceans cover 70% of the Earth's surface, our knowledge of biodiversity patterns in marine phytoplankton and zooplankton is very limited compared to that of the biodiversity of plants and herbivores in the terrestrial world. Here, we present biodiversity data for marine plankton assemblages from different areas of the world ocean. Similar to terrestrial vegetation, marine phytoplankton diversity is a unimodal function of phytoplankton biomass, with maximum diversity at intermediate levels of phytoplankton biomass and minimum diversity during massive blooms. Contrary to expectation, we did not find a relation between phytoplankton diversity and zooplankton diversity. Zooplankton diversity is a unimodal function of zooplankton biomass. Most strikingly, these marine biodiversity patterns show a worldwide consistency, despite obvious differences in environmental conditions of the various oceanographic regions. These findings may serve as a new benchmark in the search for global biodiversity patterns of plants and herbivores. 相似文献
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Detection of human leukaemia associated antigens in leukaemic serum and normal embryos 总被引:4,自引:0,他引:4
R Harris D Viza R Todd J Phillips R Sugar R F Jennison G Marriott M H Gleeson 《Nature》1971,233(5321):556-557
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Macpherson AJ Martinic MM Harris N 《Cellular and molecular life sciences : CMLS》2002,59(12):2088-2096
There is an immense load of non-pathogenic commensal bacteria in the distal small intestine and the colon of mammals. The
physical barrier that prevents penetration (translocation) of these organisms into the body is a simple epithelium comprised
of the single enterocyte/colonocyte cell layer with its overlying mucus. In this review, we discuss the roles of intestinal
T cells in initiating and regulating innate and adaptive mucosal immune responses of the mucosal immune system that avoid
or limit penetration of the commensal intestinal bacteria.
Received 9 August 2002; accepted 9 September 2002
RID="*"
ID="*"Corresponding author. 相似文献
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Bentley SD Chater KF Cerdeño-Tárraga AM Challis GL Thomson NR James KD Harris DE Quail MA Kieser H Harper D Bateman A Brown S Chandra G Chen CW Collins M Cronin A Fraser A Goble A Hidalgo J Hornsby T Howarth S Huang CH Kieser T Larke L Murphy L Oliver K O'Neil S Rabbinowitsch E Rajandream MA Rutherford K Rutter S Seeger K Saunders D Sharp S Squares R Squares S Taylor K Warren T Wietzorrek A Woodward J Barrell BG Parkhill J Hopwood DA 《Nature》2002,417(6885):141-147
Streptomyces coelicolor is a representative of the group of soil-dwelling, filamentous bacteria responsible for producing most natural antibiotics used in human and veterinary medicine. Here we report the 8,667,507 base pair linear chromosome of this organism, containing the largest number of genes so far discovered in a bacterium. The 7,825 predicted genes include more than 20 clusters coding for known or predicted secondary metabolites. The genome contains an unprecedented proportion of regulatory genes, predominantly those likely to be involved in responses to external stimuli and stresses, and many duplicated gene sets that may represent 'tissue-specific' isoforms operating in different phases of colonial development, a unique situation for a bacterium. An ancient synteny was revealed between the central 'core' of the chromosome and the whole chromosome of pathogens Mycobacterium tuberculosis and Corynebacterium diphtheriae. The genome sequence will greatly increase our understanding of microbial life in the soil as well as aiding the generation of new drug candidates by genetic engineering. 相似文献
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