Virulence of 10 human and 10 bovine isolates (5 type II and 5 type III of each origin) of group B streptococci (GBS) was measured in two experimental mouse models. In the first model, mice were intraperitoneally (i.p.) infected, and the 50% lethal doses (LD50) were significantly lower for human isolates than for bovine isolates. In the second model, abortion and lethality were recorded for mice infected intravenously (i.v.) on day 13 of pregnancy. All 10 human isolates induced abortions, whereas only 5 bovine isolates did so. There was no relationship between 50% abortive doses determined for 9 isolates (4 human and 5 bovine) and the LD50 values. Post-partum lethality was significantly correlated with LD50 values.Our studies suggested that the lethality test for nonpregnant mice and the abortion test for pregnant mice were not redundant and that the latter would be a useful additional model for identification of virulence factors of GBS. 相似文献
Summary Enzymatic O-glycosylation of dipeptide derivatives containing a serine residue in the N or C terminal position and alanine or glycine as the second amino acid was achieved using the transgalactosylation activity of -galactosidase from the Achatina achatina digestive juice. Reactions were performed with lactose as glycosyl donor and the dipeptide ethyl (or methyl) esters N-protected by a benzyloxycarbonyl group (Z) as glycosyl acceptors. Yields of galactosyl-dipeptide derivatives were much higher than those obtained with the E.coli -galactosidase as catalyst. 相似文献
Summary— We have previously shown the presence, in the amplified DNA of a Drosophila cell line resistant to N-phosphonacetyl-L-aspartate (PALA), of two units of 150 kb and 120 kb respectively duplicated and amplified. The two joints (J1 and J2) linking these units as well as their respective wild-type counterparts have been sequenced. Sequence analysis indicates that a region of the Drosophila genome which corresponds to the proximal boundary of the 150 kb unit is common to both joints. In addition to this common region, the J1 junction possesses a 26-nucleotide sequence belonging to the J2 junction. This indicates that the J2 junction was the first formed, and that J1, therefore, results from recombination between J2 and a region of the wild-type genome 120 kb distal to J2. Sequence analysis also reveals that the joints result from illegitimate recombination between unrelated regions. AT-rich sequences, strand bias composition and putative topoisomerase I and II sites were found in at least one of the two parental sequences involved in the formation of the joints. On the basis of these results we can hypothesize that after two illegitimate recombinations between sister chromatids, leading first to J2 and then to J1, the amplification may have arisen by a series of homologous (unequal crossing-over) or illegitimate recombinations, or by an intrachromosomal rolling circle. 相似文献
Journal of Physiology and Biochemistry - Thermogenic (brown and beige) adipose tissues improve glucose and lipid homeostasis and therefore represent putative targets to cure obesity and related... 相似文献
Plant and Soil - Land cover change (LCC) from natural forest (NF) to plantations (PF) has occurred worldwide over the past several decades. However, the different LCC effects on soil aggregate C... 相似文献
Inland recreational fisheries have social, economic, and ecological importance worldwide but these fisheries are increasingly challenged by the diverse effects of climate change. Coupled with other anthropogenic stressors, climate change has contributed to declines in freshwater biodiversity of greater severity than those observed across marine or terrestrial taxa. At a macro level, inland fisheries are experiencing declines. There are, however, a number of success stories, or ‘bright spots,’ in inland recreational fisheries management, where innovative approaches are leading to increases in social and ecological well-being in the face of climate change. Cases such as these are important sources of inspiration and learning about adaptation to climate and environmental change. In this article, we analyze 11 examples of such ‘bright spots’ drawn from multiple jurisdictions around the world from which we extracted lessons that might apply to fisheries management challenges beyond the region and context of each case. Collectively, these bright spots highlight adaptive initiatives that allow for recreational fisheries management to mitigate to stressors associated with current and future climate change. Examples identified include community-based restoration projects, collaborative and adaptive approaches to short-term fisheries closures, transdisciplinary large-scale conservation projects, and conservation-minded efforts by individuals and communities. By highlighting examples of ‘small wins’ within inland recreational fisheries management, this review contributes to the idea that a ‘positive future’ for inland recreational fisheries in the face of climate change is possible and highlights potential strategies to adapt to current and future climate scenarios.