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991.
Sílvia S. Monteiro José V. Vingada Alfredo López Graham J. Pierce Marisa Ferreira Andrew Brownlow 《Marine Biology Research》2016,12(6):595-607
Determining how intra-specific genetic diversity is apportioned among natural populations is essential for detecting local adaptation and identifying populations with inherently low levels of extant diversity which may become a conservation concern. Sequence polymorphism at two adaptive loci (MHC DRA and DQB) was investigated in long-finned pilot whales (Globicephala melas) from four regions in the North Atlantic and compared with previous data from New Zealand (South Pacific). Three alleles were resolved at each locus, with trans-species allele sharing and higher levels of non-synonymous to synonymous substitution, especially in the DQB locus. Overall nucleotide diversities of 0.49?±?0.38% and 4.60?±?2.39% were identified for the DRA and DQB loci, respectively, which are relatively low for MHC loci in the North Atlantic, but comparable to levels previously described in New Zealand (South Pacific). There were significant differences in allele frequencies within the North Atlantic and between the North Atlantic and New Zealand. Patterns of diversity and divergence are consistent with the long-term effects of balancing selection operating on the MHC loci, potentially mediated through the effects of host-parasite coevolution. Differences in allele frequency may reflect variation in pathogen communities, coupled with the effects of differential drift and gene flow. 相似文献
992.
Eukaryotic release factor 1 (eRF1) abolishes readthrough and competes with suppressor tRNAs at all three termination codons in messenger RNA. 总被引:6,自引:3,他引:3
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G Drugeon O Jean-Jean L Frolova X Le Goff M Philippe L Kisselev A L Haenni 《Nucleic acids research》1997,25(12):2254-2258
It is known from experiments with bacteria and eukaryotic viruses that readthrough of termination codons located within the open reading frame (ORF) of mRNAs depends on the availability of suppressor tRNA(s) and the efficiency of termination in cells. Consequently, the yield of readthrough products can be used as a measure of the activity of polypeptide chain release factor(s) (RF), key components of the translation termination machinery. Readthrough of the UAG codon located at the end of the ORF encoding the coat protein of beet necrotic yellow vein furovirus is required for virus replication. Constructs harbouring this suppressible UAG codon and derivatives containing a UGA or UAA codon in place of the UAG codon have been used in translation experiments in vitro in the absence or presence of human suppressor tRNAs. Readthrough can be virtually abolished by addition of bacterially-expressed eukaryotic RF1 (eRF1). Thus, eRF1 is functional towards all three termination codons located in a natural mRNA and efficiently competes in vitro with endogenous and exogenous suppressor tRNA(s) at the ribosomal A site. These results are consistent with a crucial role of eRF1 in translation termination and forms the essence of an in vitro assay for RF activity based on the abolishment of readthrough by eRF1. 相似文献
993.
Using a screening procedure that is based on a histochemical stain for the enzyme beta-glucuronidase, we have isolated several mutants of the nematode Caenorhabditis elegans affected in beta-glucuronidase activity. All of the mutations fall into one complementation group and identify a new gene, gus-1, which has been mapped on the right arm of linkage group I (LG I), 1.1 map units to the left of unc-54. The mutants have no visible phenotype, and their viabilities and fertilities are unaffected. Linked revertants of two of the mutations have been isolated. They restore enzyme activity to almost wild-type levels; the beta-glucuronidase that one of the revertants produces differs from that of the wild type. We propose that gus-1 is the structural locus for beta-glucuronidase. 相似文献
994.
Tracing Pediococcus acidilactici in ensiled maize by plasmid-encoded erythromycin resistance 总被引:3,自引:3,他引:0
Curing experiments undertaken on Pediococcus acidilactici strain S364, isolated from maize silage, revealed a linkage between a resident 40 MD plasmid and resistance to erythromycin, oleandomycin and tylosin. The possibility of using erythromycin resistance to monitor the fate of this strain in a model ensiling system was also demonstrated. 相似文献
995.
996.
Nerve growth factor-independent development of embryonic mouse sympathetic neurons in dissociated cell culture 总被引:8,自引:0,他引:8
Although ganglia from neonatal mouse sympathetic ganglia require nerve growth factor (NGF) for survival in culture, explanted sympathetic ganglia from early embryonic stages do not require added NGF for survival and growth. To determine whether the change in growth factor requirement is due to changes in the neurons themselves, to variations in neuronal populations, or to changes in nonneuronal cells, we examined the response to growth factors by dissociated sympathetic neurons at various stages of development. Results indicate that neurons from the 14-day gestational (E14) superior cervical ganglion (SCG) do not require NGF for initial survival and neurite extension, but do require the conditioned medium neurite extension factor, CMF. By 2 to 3 days thereafter, whether in vivo or in culture, most neurons have developed a requirement for NGF for survival in culture. During the same period, there is a concomitant increase in responsiveness to NGF alone as a trophic agent. Changes in response to NGF are not due to changes in NGF content of ganglia, to interactions in culture with nonneuronal cells, or to age-related differences in NGF requirements for maximum survival. The changes in growth factor requirements may be related to mechanisms regulating specificity of nerve-target connections. 相似文献
997.
Conformational requirements of tobacco mosaic virus RNA for aminoacylation and adenylation. 总被引:2,自引:0,他引:2
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The RNA conformational requirements for both aminoacylation and adenylation emerging from our studies performed using the valine- and the tyrosine-accepting plant viral RNAs are now strongly supported by the histidine-accepting tobacco mosaic virus RNA: an 'L'-shaped conformation is recognized by the aminoacyl-tRNA synthetase whereas only the aminoacyl RNA domain (equivalent in tRNAs to the continuous helix formed by the acceptor stem and the T stem and loop) interacts with the tRNA nucleotidyltransferase. 相似文献
998.
Gabriele Giacomo Schiattarella Fabio Cattaneo Gianluigi Pironti Fabio Magliulo Giuseppe Carotenuto Marinella Pirozzi Roman Polishchuk Domenica Borzacchiello Roberta Paolillo Marco Oliveti Nicola Boccella Marisa Avvedimento Maria Sepe Assunta Lombardi Rosa Anna Busiello Bruno Trimarco Giovanni Esposito Antonio Feliciello Cinzia Perrino 《PloS one》2016,11(5)
A-kinase anchoring proteins (AKAPs) transmit signals cues from seven-transmembrane receptors to specific sub-cellular locations. Mitochondrial AKAPs encoded by the Akap1 gene have been shown to modulate mitochondrial function and reactive oxygen species (ROS) production in the heart. Under conditions of hypoxia, mitochondrial AKAP121 undergoes proteolytic degradation mediated, at least in part, by the E3 ubiquitin ligase Seven In-Absentia Homolog 2 (Siah2). In the present study we hypothesized that Akap1 might be crucial to preserve mitochondrial function and structure, and cardiac responses to myocardial ischemia. To test this, eight-week-old Akap1 knockout mice (Akap1-/-), Siah2 knockout mice (Siah2-/-) or their wild-type (wt) littermates underwent myocardial infarction (MI) by permanent left coronary artery ligation. Age and gender matched mice of either genotype underwent a left thoracotomy without coronary ligation and were used as controls (sham). Twenty-four hours after coronary ligation, Akap1-/- mice displayed larger infarct size compared to Siah2-/- or wt mice. One week after MI, cardiac function and survival were also significantly reduced in Akap1-/- mice, while cardiac fibrosis was significantly increased. Akap1 deletion was associated with remarkable mitochondrial structural abnormalities at electron microscopy, increased ROS production and reduced mitochondrial function after MI. These alterations were associated with enhanced cardiac mitophagy and apoptosis. Autophagy inhibition by 3-methyladenine significantly reduced apoptosis and ameliorated cardiac dysfunction following MI in Akap1-/- mice. These results demonstrate that Akap1 deficiency promotes cardiac mitochondrial aberrations and mitophagy, enhancing infarct size, pathological cardiac remodeling and mortality under ischemic conditions. Thus, mitochondrial AKAPs might represent important players in the development of post-ischemic cardiac remodeling and novel therapeutic targets. 相似文献
999.
Roberto Bezerra Vital Pedro Tadao Hamamoto Filho Gustavo Jose Luvizutto Luis Gustavo Ducati Gabriel Pereira Braga Helio Rubens de Carvalho Nunes Flavio Ramalho Romero Eliana Marisa Ganem Marco Antonio Zanini Rodrigo Bazan 《PloS one》2016,11(1)