The Cyst-Dividing Bacterium Ramlibacter tataouinensis TTB310 Genome Reveals a Well-Stocked Toolbox for Adaptation to a Desert Environment

Ramlibacter tataouinensis TTB310T (strain TTB310), a betaproteobacterium isolated from a semi-arid region of South Tunisia (Tataouine), is characterized by the presence of both spherical and rod-shaped cells in pure culture. Cell division of strain TTB310 occurs by the binary fission of spherical “cyst-like” cells (“cyst-cyst” division). The rod-shaped cells formed at the periphery of a colony (consisting mainly of cysts) are highly motile and colonize a new environment, where they form a new colony by reversion to cyst-like cells. This unique cell cycle of strain TTB310, with desiccation tolerant cyst-like cells capable of division and desiccation sensitive motile rods capable of dissemination, appears to be a novel adaptation for life in a hot and dry desert environment. In order to gain insights into strain TTB310's underlying genetic repertoire and possible mechanisms responsible for its unusual lifestyle, the genome of strain TTB310 was completely sequenced and subsequently annotated. The complete genome consists of a single circular chromosome of 4,070,194 bp with an average G+C content of 70.0%, the highest among the Betaproteobacteria sequenced to date, with total of 3,899 predicted coding sequences covering 92% of the genome. We found that strain TTB310 has developed a highly complex network of two-component systems, which may utilize responses to light and perhaps a rudimentary circadian hourglass to anticipate water availability at the dew time in the middle/end of the desert winter nights and thus direct the growth window to cyclic water availability times. Other interesting features of the strain TTB310 genome that appear to be important for desiccation tolerance, including intermediary metabolism compounds such as trehalose or polyhydroxyalkanoate, and signal transduction pathways, are presented and discussed

Indiferença, simetria e perfeição segundo Leibniz

Na Teodicéia, Leibniz apresentatrês soluções para o sofisma de Buridan, em particular, e para o problema da liberdade de indiferença, em geral. A primeira refuta a idéia de que, mesmo em uma situação de perfeito equilíbrio e total ausência de uma razão determinante, os homens (diferentemente dos animais irracionais) seriam capazes de agir. As outras duas refutam diretamente a possibilidade de haver no universo tal situação de equilíbrio e simetria perfeitos, de modo que o próprio sofisma perde seu sentido.<br>In the Theodicy, Leibniz presents three different solutions to the sophism of Buridan's Ass, and more generally, to the problem of the liberty of indifference. The first criticizes the idea that, even in a situation of perfect equilibrium and complete absence of a determining reason, men (as opposed to irrational animals) would be able to act. The other two deny the very possibility of perfect equilibrium and symmetry in the universe, such that this sophism looses its meaning

Modeling recent bark stripping by red deer (Cervus elaphus) in South Belgium coniferous stands

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FMR2 expression in families with FRAXE mental retardation

Normal individuals express the two alternative transcripts, FMR2 and Ox19, from the FRAXE-associated CpG island. Molecular analysis of the Ox19 transcript suggests that it is a truncated isoform of the FMR2 gene with an alternative 3′ end. Both isoforms showed a similar pattern of expression, with the Ox19 isoform expressed at a much lower level. Fibroblasts, chorionic villi and hair roots showed the highest level of FMR2 expression, whole blood cells and amniocytes showed very low expression, and the transcript was not detected in lymphoblasts. Fibroblasts of 11 individuals from seven families segregating FRAXE were assayed for FMR2 expression and FRAXE CpG island methylation. A man with an unmethylated expansion of 0.6 kb expressed FMR2 and represents a pre-mutation carrier. All chromosomes with FRAXE CCG expansions of 0.8 kb or greater were fully methylated and did not express the FMR2 gene, analogous to the mechanism of silencing the FMR1 gene in carriers of the FRAXA full mutation. The boundary between FRAXE pre-mutation and FRAXE full mutation is between 0.7 and 0.8 kb. Two men with absence of FMR2 expression in fibroblasts were not mentally impaired, suggesting that IQ in some men with FRAXE full mutation may remain within the normal range. Although molecular tools to study FRAXE non-specific mental retardation are now available, further psychometric and molecular studies are needed to characterize the effect of the FRAXE full mutation for the purpose of genetic counselling.Jozef Gécz, Ben A. Oostra, Athel Hockey, Pablo Carbonell, Gillian Turner, Eric A. Haan, Grant R. Sutherland, and John C. Mulle