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1.
Spatial dynamics of foraging long-fingered bats (Myotis capaccinii) were studied in the Eastern Iberian Peninsula. We analysed the locations of 45 radio-tracked individuals during three discrete periods through the breeding season and measured the spatial parameters related to their foraging behaviour in order to test whether variations in spatial use occur. Colony range, measured as the minimum convex polygon through all the radiolocations, was 345 km2, but the area used during each period was smaller. During pre-breeding, foraging bats gathered at two stretches of different tributary rivers; during lactation, they scattered throughout the river system; and during weaning, they aggregated at a stretch of the main river. Individuals on average flew 5.7 km from roosts to foraging areas, with a maximum absolute distance of 22.7 km. Individual foraging ranges were measured linearly, because the bats foraged mostly along rivers; their values averaged 1.3 km/night and overlapped extensively between neighbouring bats (>65% on average). The sampling period, rather than the bats’ reproductive status, age, or sex, explained the observed variability in spatial distribution and size of hunting sites. We did not find differences in spatial parameters between lactating females and non-lactating bats, nor between juveniles and adults. This is the first study to split the independent effects of season and population class in order to enable unconfounded interpretations of the spatial dynamics of foraging reproductive females and juveniles. We speculate that the relationship between colony size and prey availability ruled the observed changes in foraging area through seasons. The considerable overlap in individual foraging ranges may be a necessary adaption to large colonies forced by the specific roost requirements of the long-fingered bat and the narrow foraging niche they appear to occupy.  相似文献   
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To perform a genetic analysis of the influenza A virus NS1 gene, a library of NS1 mutants was generated by PCR-mediated mutagenesis. A collection of mutant ribonucleic proteins containing the nonstructural genes was generated from the library that were rescued for an infectious virus mutant library by a novel RNP competition virus rescue procedure. Several temperature-sensitive (ts) mutant viruses were obtained by screening of the mutant library, and the sequences of their NS1 genes were determined. Most of the mutations identified led to amino acid exchanges and concentrated in the N-terminal region of the protein, but some of them occurred in the C-terminal region. Mutant 11C contained three mutations that led to amino acid exchanges, V18A, R44K, and S195P, all of which were required for the ts phenotype, and was characterized further. Several steps in the infection were slightly altered: (i) M1, M2, NS1, and neuraminidase (NA) accumulations were reduced and (ii) NS1 protein was retained in the nucleus in a temperature-independent manner, but these modifications could not justify the strong virus titer reduction at restrictive temperature. The most dramatic phenotype was the almost complete absence of virus particles in the culture medium, in spite of normal accumulation and nucleocytoplasmic export of virus RNPs. The function affected in the 11C mutant was required late in the infection, as documented by shift-up and shift-down experiments. The defect in virion production was not due to reduced NA expression, as virus yield could not be rescued by exogenous neuraminidase treatment. All together, the analysis of 11C mutant phenotype may indicate a role for NS1 protein in a late event in virus morphogenesis.  相似文献   
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Food availability and pond desiccation are two of the most studied factors that condition amphibian metamorphosis. It is well known that, when food is abundant, organisms undergo metamorphosis early and when they are relatively large. The capability of anurans to accelerate their developmental rate in response to desiccation is also common knowledge. These two variables must act together in nature, since we know that, as a pond dries, the per capita resources decrease. We conduct an experiment to evaluate the effects of desiccation and food availability separately and in combination in tadpoles of the painted frog (Discoglossus pictus). We demonstrate that food deprivation leads to slow growth rates, which delay metamorphosis and produce smaller size and weight. The capability to accelerate metamorphosis when facing a drying pond is also confirmed, but, nevertheless, with factor interaction (when the pool is drying and resources are scarce) the capacity to respond to desiccation is lost. In addition, slow drying rates are shown to be stressful situations, but not enough to provoke a shortening of the larval period; in fact, the larval period becomes longer. We also demonstrate that the interaction of these factors changes the allometric relationship of different parts of the hind limb, which has implications for the biomechanics of jumping. Due to low mortality rates and an adequate response to both environmental factors, we expect D. pictus to have a great invasive potential in its new Mediterranean distribution area, where lots of temporary and ephemeral ponds are present.  相似文献   
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Lysosomal biomarkers are early warning signals of the biological effects caused by environmental pollutants but the promptness of lysosomal responses to pollutants has not been investigated yet. This work is aimed to determine the response-time of digestive cell lysosomes in mussels exposed to metals and hydrocarbons. Mussels, Mytilus galloprovincialis, were exposed, under laboratory conditions to Cd and to the water-accommodated fraction of a lubricant oil. One mussel per experimental group was sacrificed and processed every hour from 0 h to 30 h. Changes in AcP activity, immunoreactivity and LMS test based on AcP histochemistry, discriminates significantly control and exposed mussels within 5 h exposure. The present results suggested that after 15–20 h exposure digestive cell loss might be accompanied by increased AcP activity (extralysosomal) without a parallel increase in the levels of immunoreactive AcP protein, especially after Cd-exposure. The reduced labilisation period of lysosomal membrane constitute a cost effective early warning signal that, however, is not necessarily correlated with the exposure time. The routine application of immunochemical techniques deserves more research efforts before its implementation although, these techniques are very valuable to understand and interpret correctly lysosomal responses to pollutants.  相似文献   
7.
Goiti  Urtzi  Vecin  Patricia  Garin  Inazio  Saloña  Marta  Aihartza  Jose R. 《Acta theriologica》2003,48(4):457-468
The trophic ecology of Kuhl’s pipistrellePipistrellus kuhlii (Kuhl, 1817) was investigated monthly from May to October 1999. Nine insect and two arachnid orders were identified in faeces and classified in 24 different categories. The most frequently occurring prey categories were Culicidae, Lepidoptera, Chironomidae/Ceratopogonidae, Hymenoptera, unidentified Brachycera, Tipulidae and unidentified Coleoptera in decreasing order. Other categories exhibited seasonal importance, such as the coleopteranRhizotrogus sp. Prey availability was evaluated monthly using Malaise traps in known feeding areas. Bats preyed selectively through a temporarily changing pattern. Some taxa constituted an important part of the diet and were positively selected either monthly or in most of the months. Many of them were the largest prey featuring in the diet and changes of their relative profitability across time would determine their selection index. The small size of some prey categories as well asP.kuhlii’s morphofunctional constraints relative to flight and echolocation could explain their underexploitation or rejection. Our results suggest thatP. kuhlii could be regarded as a ‘selective opportunist’ species.  相似文献   
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Stress granules (SGs) are cytoplasmic structures that are induced in response to environmental stress, including viral infections. Here we report that hepatitis C virus (HCV) triggers the appearance of SGs in a PKR- and interferon (IFN)-dependent manner. Moreover, we show an inverse correlation between the presence of stress granules and the induction of IFN-stimulated proteins, i.e., MxA and USP18, in HCV-infected cells despite high-level expression of the corresponding MxA and USP18 mRNAs, suggesting that interferon-stimulated gene translation is inhibited in stress granule-containing HCV-infected cells. Finally, in short hairpin RNA (shRNA) knockdown experiments, we found that the stress granule proteins T-cell-restricted intracellular antigen 1 (TIA-1), TIA1-related protein (TIAR), and RasGAP-SH3 domain binding protein 1 (G3BP1) are required for efficient HCV RNA and protein accumulation at early time points in the infection and that G3BP1 and TIA-1 are required for intracellular and extracellular infectious virus production late in the infection, suggesting that they are required for virus assembly. In contrast, TIAR downregulation decreases extracellular infectious virus titers with little effect on intracellular RNA content or infectivity late in the infection, suggesting that it is required for infectious particle release. Collectively, these results illustrate that HCV exploits the stress granule machinery at least two ways: by inducing the formation of SGs by triggering PKR phosphorylation, thereby downregulating the translation of antiviral interferon-stimulated genes, and by co-opting SG proteins for its replication, assembly, and egress.  相似文献   
10.

Background

Chronic hepatitis B virus (HBV) infection remains incurable. Although HBsAg-specific chimeric antigen receptor (HBsAg-CAR) T cells have been generated, they have not been tested in animal models with authentic HBV infection.

Methods

We generated a novel CAR targeting HBsAg and evaluated its ability to recognize HBV+ cell lines and HBsAg particles in vitro. In vivo, we tested whether human HBsAg-CAR T cells would have efficacy against HBV-infected hepatocytes in human liver chimeric mice.

Results

HBsAg-CAR T cells recognized HBV-positive cell lines and HBsAg particles in vitro as judged by cytokine production. However, HBsAg-CAR T cells did not kill HBV-positive cell lines in cytotoxicity assays. Adoptive transfer of HBsAg-CAR T cells into HBV-infected humanized mice resulted in accumulation within the liver and a significant decrease in plasma HBsAg and HBV-DNA levels compared with control mice. Notably, the fraction of HBV core–positive hepatocytes among total human hepatocytes was greatly reduced after HBsAg-CAR T cell treatment, pointing to noncytopathic viral clearance. In agreement, changes in surrogate human plasma albumin levels were not significantly different between treatment and control groups.

Conclusions

HBsAg-CAR T cells have anti-HBV activity in an authentic preclinical HBV infection model. Our results warrant further preclinical exploration of HBsAg-CAR T cells as immunotherapy for HBV.  相似文献   
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