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21.
Hüiwan Han Dali Shao Jinyi Wu Germaine Cornélissen Franz Halberg 《Cell biochemistry and biophysics》1991,18(3):217-229
An earlier demonstration of a circadian rhythm in rat atria by others is complemented herein by observations in culture: A single murine myocardial cell and two sets of grouped cells beating in culture for several days reveal several features of an anticipated, presumably built-in spectrum of multifrequency rhythms and trends, the chronome. Circadian and about 12-h (circasemidian) components are modulated by an approximately 84-h (circasemiseptan) component, which cannot be separated from trends in view of the brevity of the series. The circumstance under which the culture is aging and in which fibroblasts proliferate is a further complication that limits the findings to a single cycle reproduced in three separate cultures. Whether it is a rhythm that repeats itself or a response to placement into culture, an approximately 3.5-d component in the beating of myocardial cells in culture is to be aligned with a very prominent similar component found in the incidence of 85,819 human myocardial infarctions. 相似文献
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A real-time PCR assay is described for detection of the macrolide efflux gene, mef. Following amplification, unambiguous discrimination between the two mef subclasses, mef(A) and mef(E), is easily established using a melting curve analysis. The results of this novel assay were 100% concordant with a conventional PCR-RFLP approach but requires far less hands-on time. Furthermore, the real-time format offers semiquantitative results allowing identification of contaminated cultures and/or DNA preparations. 相似文献
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Larson MA Bressani R Sayood K Corn JE Berger JM Griep MA Hinrichs SH 《Nucleic acids research》2008,36(16):5260-5269
The placement of the extreme thermophile Aquifex aeolicus in the bacterial phylogenetic tree has evoked much controversy. We investigated whether adaptations for growth at high temperatures would alter a key functional component of the replication machinery, specifically DnaG primase. Although the structure of bacterial primases is conserved, the trinucleotide initiation specificity for A. aeolicus was hypothesized to differ from other microbes as an adaptation to a geothermal milieu. To determine the full range of A. aeolicus primase activity, two oligonucleotides were designed that comprised all potential trinucleotide initiation sequences. One of the screening templates supported primer synthesis and the lengths of the resulting primers were used to predict possible initiation trinucleotides. Use of trinucleotide-specific templates demonstrated that the preferred initiation trinucleotide sequence for A. aeolicus primase was 5′-d(CCC)-3′. Two other sequences, 5′-d(GCC)-3′ and d(CGC)-3′, were also capable of supporting initiation, but to a much lesser degree. None of these trinucleotides were known to be recognition sequences used by other microbial primases. These results suggest that the initiation specificity of A. aeolicus primase may represent an adaptation to a thermophilic environment. 相似文献
26.
Stephen A. Diamond Peter C. Trenham Michael J. Adams Blake R. Hossack Roland A. Knapp Stacey L. Stark David Bradford P. Stephen Corn Ken Czarnowski Paul D. Brooks Dan Fagre Bob Breen Naomi E. Detenbeck Kathy Tonnessen 《Ecosystems》2005,8(5):462-477
Ultraviolet-B radiation (UV-B, 280–320-nm wavelengths) doses were estimated for 1024 wetlands in six national parks: Acadia
(Acadia), Glacier (Glacier), Great Smoky Mountains (Smoky), Olympic (Olympic), Rocky Mountain (Rocky), and Sequoia/Kings Canyon
(Sequoia). Estimates were made using ground-based UV-B data (Brewer spectrophotometers), solar radiation models, GIS tools,
field characterization of vegetative features, and quantification of DOC concentration and spectral absorbance. UV-B dose
estimates were made for the summer solstice, at a depth of 1 cm in each wetland. The mean dose across all wetlands and parks
was 19.3 W-h m−2 (range of 3.4–32.1 W-h m−2). The mean dose was lowest in Acadia (13.7 W-h m−2) and highest in Rocky (24.4 W-h m−2). Doses were significantly different among all parks. These wetland doses correspond to UV-B flux of 125.0 μW cm−2 (range 21.4–194.7 μW cm−2) based on a day length, averaged among all parks, of 15.5 h. Dissolved organic carbon (DOC), a key determinant of water-column
UV-B flux, ranged from 0.6 (analytical detection limit) to 36.7 mg C L−1 over all wetlands and parks, and reduced potential maximal UV-B doses at 1-cm depth by 1%–87 %. DOC concentration, as well
as its effect on dose, was lowest in Sequoia and highest in Acadia (DOC was equivalent in Acadia, Glacier, and Rocky). Landscape
reduction of potential maximal UV-B doses ranged from zero to 77% and was lowest in Sequoia. These regional differences in
UV-B wetland dose illustrate the importance of considering all aspects of exposure in evaluating the potential impact of UV-B
on aquatic organisms. 相似文献
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In cancer and other therapeutic research, an interpretation of median survival times can and should take cure into account. With this qualification, an analysis of recently published data provides further statistically significant evidence in favor of cancer chronotherapy as compared to homeostatic therapy. 相似文献
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J P Durbec J Cornée 《Comptes rendus des séances de la Société de biologie et de ses filiales》1975,169(4):1012-1020
Correspondances analysis dealing with four hundred items of pain in patients suffering of various digestive diseases showed relations between the localisations and temporal evolution of pain. A critical study of results with regard to different diagnoses has been performed. 相似文献