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- Thompson, Luke R., et al.
(författare)
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A communal catalogue reveals Earth's multiscale microbial diversity
- 2017
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 551:7681, s. 457-463
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Our growing awareness of the microbial world's importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth's microbial diversity.
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- Lohmander, Stefan, et al.
(författare)
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Chemical and metabolic heterogeneity of chondroitin sulfate and keratan sulfate in guinea pig cartilage and nucleus pulposus
- 1973
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Ingår i: Biochimica et Biophysica Acta. General Subjects. - : Elsevier BV. - 0304-4165. ; 304:2, s. 430-448
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Tidskriftsartikel (refereegranskat)abstract
- Chondroitin sulfate and keratan sulfate in guinea pig costal cartilage, nasal septum cartilage and nucleus pulposus were separated and fractionated by chromatography on CPC-cellulose, ECTEOLA-cellulose and Sephadex G-200 columns. Characterization of the chondroitin sulfates included determination of molecular weight and of the number, and position, of sulfate groups of the disaccharide units. Distinct chemical differences were found between the total fractions of chondroitin sulfate from the three tissues. Within the total fractions a marked heterogeneity was also apparent. The turnover of the two glycosaminoglycans was studied by using radioactive sulfate as precursor. The guinea pigs were killed at eight intervals, ranging from 30 min to 40 days after injection of the isotope. Total fractions of chondroitin sulfate from rib, nasal septum and nucleus pulposus showed half-lives of about 80, 40 and 30 days, respectively. In addition, the existence of a second metabolic component with a faster turnover (half-life about 3 days) was indicated in chondroitin sulfate from all three tissues. Similarly, keratan sulfate from the rib contained a 'slow' component with a half-life of about 90 days and a 'fast' component with a half-life of 4 days. For keratan sulfate from nucleus pulposus only a single component was demonstrable; it had a half-life of about 30 days. Within the total fractions of both chondroitin sulfate and keratan sulfate from the three tissues studied, a considerable degree of metabolic heterogeneity was apparent between, and within, subfractions of differing molecular weight.
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