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Female white-footed mice (Peromyscus leucopus) fail to produce offspring when paired with a male from weaning until 150 days of age if an adult female or her odor is also present. The present study delineates more clearly which stage of the young female's reproductive cycle is inhibited by the chemosignal of the older female. Age at vaginal opening and first estrus are delayed by the presence of the older female, but only for about 10 days. The presence of a male counteracts this delay. Thus, the basis for the block is not a delay in puberty. The older female's presence does not influence the number of estrous cycles experienced during the 30 days following first estrus, nor does it influence the number of corpora lutea found at autopsy. The presence of sperm in the vaginae of young females indicates that they were copulating. Likewise, examination of embryos 2 and 3 days after copulation reveals normal developmental progress. However, implantation does not occur in young females that have been exposed to an adult female. Thus, the block occurs either during the final stages of embryo transport or in relation to the implantation process itself.  相似文献   
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The effectiveness of combining the subcutaneous administration of short- and intermediate-acting insulin with the intravenous infusion of glucose in maintaining normoglycemia during labour and delivery in insulin-dependent diabetic women was tested. Fifty women were given intermediate-acting insulin twice daily in doses that were fractions of their usual dose, based on the projected duration of labour. In addition, they were given regular (i.e., short-acting) insulin every 6 hours, the dose being 1% of their total daily insulin dose for every increase of 10 mg/dl above 100 mg/dl (5.6 mmol/l) in the plasma glucose level 1 hour previously; the levels were measured every 3 hours. All the patients were fasting and received a basal intravenous infusion of 6 g/h of glucose; the rate of infusion was increased by 1 g/h for every decrease of 10 mg/dl in the plasma glucose level below 100 mg/dl. The mean plasma glucose levels (+/- standard deviation) were 90 +/- 46 mg/dl after 3 hours of labour, 92 +/- 35 mg/dl after 6 hours, 97 +/- 49 mg/dl after 9 hours and 107 +/- 65 mg/dl after 12 hours. With only one exception, in a premature infant, the 5-minute Apgar scores were identical to those of the infants of nondiabetic women.  相似文献   
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Listeria monocytogenes is a foodborne pathogen causing systemic infection with high mortality. To allow efficient tracking of outbreaks a clear definition of the genomic signature of a cluster of related isolates is required, but lineage-specific characteristics call for a more detailed understanding of evolution. In our work, we used core genome MLST (cgMLST) to identify new outbreaks combined to core genome SNP analysis to characterize the population structure and gene flow between lineages. Whilst analysing differences between the four lineages of L. monocytogenes we have detected differences in the recombination rate, and interestingly also divergence in the SNP differences between sub-lineages. In addition, the exchange of core genome variation between the lineages exhibited a distinct pattern, with lineage III being the best donor for horizontal gene transfer. Whilst attempting to link bacteriophage-mediated transduction to observed gene transfer, we found an inverse correlation between phage presence in a lineage and the extent of recombination. Irrespective of the profound differences in recombination rates observed between sub-lineages and lineages, we found that the previously proposed cut-off of 10 allelic differences in cgMLST can be still considered valid for the definition of a foodborne outbreak cluster of L. monocytogenes.  相似文献   
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Members of the RNaseA family are present in various tissues and secretions but their function is not well understood. Some of the RNases are proposed to participate in host defence. RNase4 and RNase5 are present in cows' milk and have antimicrobial activity. However, their presence in many tissues and secretions has not been characterised. We hypothesised that these two RNases are present in a range of tissues and secretions where they could contribute to host defence. We therefore, determined the relative abundance of RNase4 and RNase5 mRNA as well as protein levels in a range of host defence related and other tissues as well as a range of secretions in cattle, using real time PCR and western blotting. The two RNases were found to be expressed in liver, lung, pancreas, mammary gland, placenta, endometrium, small intestine, seminal vesicle, salivary gland, kidney, spleen, lymph node, skin as well as testes. Corresponding proteins were also detected in many of the above tissues, as well as in seminal fluid, mammary secretions and saliva. This study provides evidence for the presence of RNase4 and RNase5 in a range of tissues and secretions, as well as some major organs in cattle. The data are consistent with the idea that these proteins could contribute to host defence in these locations. This work contributes to growing body of data suggesting that these proteins contribute to the physiology of the organism in a more complex way than acting merely as digestive enzymes.  相似文献   
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Cell migration is essential during development, regeneration, homeostasis, and disease. Depending on the microenvironment, cells use different mechanisms to migrate. Yet, all modes of migration require the establishment of an intracellular front–rear polarity axis for directional movement. Although front–rear polarity can be easily identified in in vitro conditions, its assessment in vivo by live‐imaging is challenging due to tissue complexity and lack of reliable markers. Here, we describe a novel and unique double fluorescent reporter mouse line to study front–rear cell polarity in living tissues, called GNrep. This mouse line simultaneously labels Golgi complexes and nuclei allowing the assignment of a nucleus‐to‐Golgi axis to each cell, which functions as a readout for cell front–rear polarity. As a proof‐of‐principle, we validated the efficiency of the GNrep line using an endothelial‐specific Cre mouse line. We show that the GNrep labels the nucleus and the Golgi apparatus of endothelial cells with very high efficiency and high specificity. Importantly, the features of fluorescent intensity and localization for both mCherry and eGFP fluorescent intensity and localization allow automated segmentation and assignment of polarity vectors in complex tissues, making GNrep a great tool to study cell behavior in large‐scale automated analyses. Altogether, the GNrep mouse line, in combination with different Cre recombinase lines, is a novel and unique tool to study of front–rear polarity in mice, both in fixed tissues or in intravital live imaging. This new line will be instrumental to understand cell migration and polarity in development, homeostasis, and disease.  相似文献   
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The hitch-hiking effect of a favourable gene   总被引:70,自引:0,他引:70  
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