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31.
The initiation of protein synthesis on mRNAs within eukaryotic cells is achieved either by a 5' cap-dependent mechanism or through internal initiation directed by an internal ribosome entry site (IRES). Picornavirus IRES elements, located in the 5' untranslated region (5'UTR), contain extensive secondary structure and multiple upstream AUG codons. These features can be expected to inhibit cap-dependent initiation of translation. However, we have now shown that certain mutant hepatitis C virus-like picornavirus IRES elements (from porcine teschovirus-1 and avian encephalomyelitis virus), which are unable to direct internal initiation, are not significant barriers to efficient translation of capped monocistronic mRNAs that contain these defective elements within their 5'UTRs. Moreover, the translation of these mRNAs is highly sensitive to the expression of an enterovirus 2A protease (which induces cleavage of eIF4G) and is also inhibited by hippuristanol, a specific inhibitor of eIF4A function, in contrast to their parental wild-type IRES elements. These results provide a possible basis for the evolution of viral IRES elements within the context of functional mRNAs that are translated by a cap-dependent mechanism. 相似文献
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We consider a very simple adaptive rule that induces cooperative behavior in a large class of dilemma games. The rule has a Pavlovian flavor and can be described as win-continue, lose-reverse. It assumes no knowledge about the underlying structure of the environment (the "rules of the game") and requires very little cognitive effort. Both features make it an appealing candidate for explaining the emergence of cooperative behavior in non-human species. 相似文献
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KC Lødrup Carlsen S Roll KH Carlsen P Mowinckel AH Wijga B Brunekreef M Torrent G Roberts SH Arshad I Kull U Krämer A von Berg E Eller A Høst C Kuehni B Spycher J Sunyer CM Chen A Reich A Asarnoj C Puig O Herbarth JM Mahachie John K Van Steen SN Willich U Wahn S Lau T Keil;GALEN WP . ‘Birth Cohorts’ working group 《PloS one》2012,7(8):e43214
Objective
To examine the associations between pet keeping in early childhood and asthma and allergies in children aged 6–10 years.Design
Pooled analysis of individual participant data of 11 prospective European birth cohorts that recruited a total of over 22,000 children in the 1990s.Exposure definition
Ownership of only cats, dogs, birds, rodents, or cats/dogs combined during the first 2 years of life.Outcome definition
Current asthma (primary outcome), allergic asthma, allergic rhinitis and allergic sensitization during 6–10 years of age.Data synthesis
Three-step approach: (i) Common definition of outcome and exposure variables across cohorts; (ii) calculation of adjusted effect estimates for each cohort; (iii) pooling of effect estimates by using random effects meta-analysis models.Results
We found no association between furry and feathered pet keeping early in life and asthma in school age. For example, the odds ratio for asthma comparing cat ownership with “no pets” (10 studies, 11489 participants) was 1.00 (95% confidence interval 0.78 to 1.28) (I2 = 9%; p = 0.36). The odds ratio for asthma comparing dog ownership with “no pets” (9 studies, 11433 participants) was 0.77 (0.58 to 1.03) (I2 = 0%, p = 0.89). Owning both cat(s) and dog(s) compared to “no pets” resulted in an odds ratio of 1.04 (0.59 to 1.84) (I2 = 33%, p = 0.18). Similarly, for allergic asthma and for allergic rhinitis we did not find associations regarding any type of pet ownership early in life. However, we found some evidence for an association between ownership of furry pets during the first 2 years of life and reduced likelihood of becoming sensitized to aero-allergens.Conclusions
Pet ownership in early life did not appear to either increase or reduce the risk of asthma or allergic rhinitis symptoms in children aged 6–10. Advice from health care practitioners to avoid or to specifically acquire pets for primary prevention of asthma or allergic rhinitis in children should not be given. 相似文献37.
Inga Herpfer Henning Hezel Wilfried Reichardt Kristin Clark Julia Geiger Claus M. Gross Andrea Heyer Valentin Neagu Harsharan Bhatia Hasan C. Atas Bernd L. Fiebich Josef Bischofberger Carola A. Haas Klaus Lieb Claus Normann 《PloS one》2012,7(10)
Background
Early life trauma is an important risk factor for many psychiatric and somatic disorders in adulthood. As a growing body of evidence suggests that brain plasticity is disturbed in affective disorders, we examined the short-term and remote effects of early life stress on different forms of brain plasticity.Methodology/Principal Findings
Mice were subjected to early deprivation by individually separating pups from their dam in the first two weeks after birth. Distinct forms of brain plasticity were assessed in the hippocampus by longitudinal MR volumetry, immunohistochemistry of neurogenesis, and whole-cell patch-clamp measurements of synaptic plasticity. Depression-related behavior was assessed by the forced swimming test in adult animals. Neuropeptides and their receptors were determined by real-time PCR and immunoassay. Early maternal deprivation caused a loss of hippocampal volume, which returned to normal in adulthood. Adult neurogenesis was unaffected by early life stress. Long-term synaptic potentiation, however, was normal immediately after the end of the stress protocol but was impaired in adult animals. In the forced swimming test, adult animals that had been subjected to early life stress showed increased immobility time. Levels of substance P were increased both in young and adult animals after early deprivation.Conclusion
Hippocampal volume was affected by early life stress but recovered in adulthood which corresponded to normal adult neurogenesis. Synaptic plasticity, however, exhibited a delayed impairment. The modulation of synaptic plasticity by early life stress might contribute to affective dysfunction in adulthood. 相似文献38.
Secretion of hyperglycaemic hormone from the corpus cardiacum of flying blowflies, Calliphora erythrocephala 总被引:2,自引:0,他引:2
In flies with an intact brain-corpus cardiacum system, the haemolymph trehalose concentration is kept near the resting level (~23 g/l.) during continuous flight for at least 45 min. Upon cardiacectomy or corpus cardiacum denervation haemolymph trehalose decreases during the first 15 min of flight to one-third of the resting level, and complete flight exhaustion occurs within 45 min. In such flight-exhausted flies a slow, apparently hormone-independent, increase of haemolymph trehalose occurs during subsequent rest. Squeezing of denervated (i.e. non-secreting) corpora cardiaca in situ in flight-exhausted flies leads temporarily to a steep rise of haemolymph trehalose level and restoration of flight performance. 相似文献
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Marion Kuhn Nora H?ger Bernd Feige Jens Blechert Claus Normann Christoph Nissen 《PloS one》2014,9(12)