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A mathematical model for traveling bands of motile and chemotactic bacteria in the presence of cell growth and death is examined.
It is found that asymptotic traveling wave solutions exist in the absence of chemotaxis, due to the balance of growth, death
and random motility. Thus random motility confers the ecological advantage of population propagation through migration into
nutrient-rich regions. The presence of chemotaxis amplifies this advantage by moving more cells into higher nutrient concentration
regions, resulting in larger and faster bands. Therefore there seem to be two types of traveling bands that can be attained
by chemotactic bacteria in the presence of growth and death: (1) these growth/death/motility bands; and (2) pure chemotactic
‘Keller-Segel'-type bands. Comparison to experimental observations by Chapman in 1973 indicate that the latter seem to be
formed. The relationship between these two types of solution is at present uncertain. The growth/death/motility bands may
have relevance on longer time or distance scales characteristic of microbial ecological systems. 相似文献
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Mavericks are virus-like mobile genetic elements found in the genomes of eukaryotes. Although Mavericks encode capsid morphogenesis homologs, their viral particles have not been observed. Here, we provide new evidence supporting the viral nature of Mavericks and the potential existence of virions. To this end, we conducted a phylogenomic analysis of Mavericks in hundreds of vertebrate genomes, discovering 134 elements with an intact coding capacity in 17 host species. We reveal an extensive genomic fossil record in 143 species and date three groups of elements to the Late Cretaceous. Bayesian phylogenetic analysis using genomic fossil orthologs suggests that Mavericks have infected osteichthyans for ∼419 My. They have undergone frequent cross-species transmissions in cyprinid fish and all core genes are subject to strong purifying selection. We conclude that vertebrate Mavericks form an ancient lineage of aquatic dsDNA viruses which are probably still functional in some vertebrate lineages. 相似文献
5.
The Fo subunits of the Escherichia coli F1Fo-ATP synthase are sufficient to form a functional proton pore 总被引:11,自引:0,他引:11
The assembly of the Fo sector of the Escherichia coli ATP synthase has been studied using both structural and functional criteria for assembly. Cross-linking E. coli minicell membranes containing only the Fo subunits a, b, and c with dithiobis(succinimidyl propionate) (DSP) produces b2 and c2 dimers that are generated by cross-linking membranes containing the assembled holoenzyme. Five plasmids carrying the genes specifying the Fo polypeptides in a bacterial strain lacking all of the unc (ATP synthase) genes show a good correlation between Fo function and the amount of the membrane-bound Fo polypeptides. In this report we revise a conclusion reached previously (Klionsky, D.J., Brusilow, W.S.A., and Simoni, R.D. (1983) J. Biol. Chem. 258, 10136-10143) and present evidence that the Fo subunits alone are sufficient to assemble a functional proton pore. 相似文献
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Suresh Anand Sadananthan Mya Thway Tint Navin Michael Izzuddin M. Aris See Ling Loy Kuan Jin Lee Lynette Pei‐Chi Shek Fabian Kok Peng Yap Kok Hian Tan Keith M. Godfrey Melvin Khee‐Shing Leow Yung Seng Lee Michael S. Kramer Peter D. Gluckman Yap Seng Chong Neerja Karnani Christiani Jeyakumar Henry Marielle Valerie Fortier S. Sendhil Velan 《Obesity (Silver Spring, Md.)》2019,27(3):470-478
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Non-enzymic in vitro formation of nitrosamines by bacteria isolated from meat products 总被引:3,自引:0,他引:3
D L Collins-Thompson N P Sen B Aris L Schwinghamer 《Canadian journal of microbiology》1972,18(12):1968-1971
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