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A simplified method for the preparation of rotifers for transmission and scanning electron microscopy 总被引:1,自引:0,他引:1
Tor TEM and SEM prepatations, rotifers are placed in little panels made of plastic Beem capsules normally used for embedding, with their conical parts cut off and closed by plankton filter cloth. Thus, the risk of losing animals is considerably reduced. 相似文献
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Caburet S Zavadakova P Ben-Neriah Z Bouhali K Dipietromaria A Charon C Besse C Laissue P Chalifa-Caspi V Christin-Maitre S Vaiman D Levi G Veitia RA Fellous M 《PloS one》2012,7(3):e33412
Background
The human condition known as Premature Ovarian Failure (POF) is characterized by loss of ovarian function before the age of 40. A majority of POF cases are sporadic, but 10–15% are familial, suggesting a genetic origin of the disease. Although several causal mutations have been identified, the etiology of POF is still unknown for about 90% of the patients.Methodology/Principal Findings
We report a genome-wide linkage and homozygosity analysis in one large consanguineous Middle-Eastern POF-affected family presenting an autosomal recessive pattern of inheritance. We identified two regions with a LODmax of 3.26 on chromosome 7p21.1-15.3 and 7q21.3-22.2, which are supported as candidate regions by homozygosity mapping. Sequencing of the coding exons and known regulatory sequences of three candidate genes (DLX5, DLX6 and DSS1) included within the largest region did not reveal any causal mutations.Conclusions/Significance
We detect two novel POF-associated loci on human chromosome 7, opening the way to the identification of new genes involved in the control of ovarian development and function. 相似文献44.
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Bacteriocins are antimicrobial peptides generally active against bacteria closely related to the producer. Escherichia coli produces two types of bacteriocins, colicins and microcins. The in vitro efficacy of isolated colicins E1, E6, E7, K and M, was assessed against Escherichia coli strains from patients with bacteraemia of urinary tract origin. Colicin E7 was most effective, as only 13% of the tested strains were resistant. On the other hand, 32%, 33%, 43% and 53% of the tested strains exhibited resistance to colicins E6, K, M and E1. Moreover, the inhibitory activity of individual colicins E1, E6, E7, K and M and combinations of colicins K, M, E7 and E1, E6, E7, K, M were followed in liquid broth for 24 hours. Resistance against individual colicins developed after 9 hours of treatment. On the contrary, resistance development against the combined action of 5 colicins was not observed. One hundred and five E. coli strains from patients with bacteraemia were screened by PCR for the presence of 5 colicins and 7 microcins. Sixty-six percent of the strains encoded at least one bacteriocin, 43% one or more colicins, and 54% one or more microcins. Microcins were found to co-occur with toxins, siderophores, adhesins and with the Toll/Interleukin-1 receptor domain-containing protein involved in suppression of innate immunity, and were significantly more prevalent among strains from non-immunocompromised patients. In addition, microcins were highly prevalent among non-multidrug-resistant strains compared to multidrug-resistant strains. Our results indicate that microcins contribute to virulence of E. coli instigating bacteraemia of urinary tract origin. 相似文献
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The Escherichia coli (E. coli) SOS response is the largest, most complex, and best characterized bacterial network induced by DNA damage. It is controlled by a complex network involving the RecA and LexA proteins. We have previously shown that the SOS response to DNA damage is inhibited by various elements involved in the expression of the E. coli toxin-antitoxin mazEF pathway. Since the mazEF module is present on the chromosomes of most E. coli strains, here we asked: Why is the SOS response found in so many E. coli strains? Is the mazEF module present but inactive in those strains? We examined three E. coli strains used for studies of the SOS response, strains AB1932, BW25113, and MG1655. We found that each of these strains is either missing or inhibiting one of several elements involved in the expression of the mazEF-mediated death pathway. Thus, the SOS response only takes place in E. coli cells in which one or more elements of the E. coli toxin-antitoxin module mazEF or its downstream pathway is not functioning. 相似文献
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Several phenotypic properties of dissociated rat embryo cerebral cells cultivated in the absence of serum on poly(l-lysine) coated surfaces were investigated. A great enrichment of neuronal cells is attained after 3–4 weeks in culture as a result of cessation of nonneuronal cell proliferation. The monolayer pattern of cell-cell reassociation and neuritic sprouting is promoted by poly(l-lysine) and it is independent of serum presence or the existence of a layer of nonneuronal cells. Synaptic profiles and typical regions of neuropil are prominent. The neuronal plasma membrane is often characterized by irregular foldings at points of cell-cell contacts. A few biochemical parameters investigated lend support to the suggestion that the cerebral neurons acquire a certain state of functional maturation. It is proposed that substances secreted by the cells or released as a result of cell death may be conspicuous components for long-term survival of the cerebral neurons. 相似文献
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