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21.
Kevin CR Kerr Sharon M Birks Mikhail V Kalyakin Yaroslav A Red'kin Eugeny A Koblik Paul DN Hebert 《Frontiers in zoology》2009,6(1):1-13
Background
Many fish species experience long periods of fasting in nature often associated with seasonal reductions in water temperature and prey availability or spawning migrations. During periods of nutrient restriction, changes in metabolism occur to provide cellular energy via catabolic processes. Muscle is particularly affected by prolonged fasting as myofibrillar proteins act as a major energy source. To investigate the mechanisms of metabolic reorganisation with fasting and refeeding in a saltwater stage of Atlantic salmon (Salmo salar L.) we analysed the expression of genes involved in myogenesis, growth signalling, lipid biosynthesis and myofibrillar protein degradation and synthesis pathways using qPCR.Results
Hierarchical clustering of gene expression data revealed three clusters. The first cluster comprised genes involved in lipid metabolism and triacylglycerol synthesis (ALDOB, DGAT1 and LPL) which had peak expression 3-14d after refeeding. The second cluster comprised ADIPOQ, MLC2, IGF-I and TALDO1, with peak expression 14-32d after refeeding. Cluster III contained genes strongly down regulated as an initial response to feeding and included the ubiquitin ligases MuRF1 and MAFbx, myogenic regulatory factors and some metabolic genes.Conclusion
Early responses to refeeding in fasted salmon included the synthesis of triacylglycerols and activation of the adipogenic differentiation program. Inhibition of MuRF1 and MAFbx respectively may result in decreased degradation and concomitant increased production of myofibrillar proteins. Both of these processes preceded any increase in expression of myogenic regulatory factors and IGF-I. These responses could be a necessary strategy for an animal adapted to long periods of food deprivation whereby energy reserves are replenished prior to the resumption of myogenesis. 相似文献22.
Marcelo L Laia Leandro M Moreira Juliana Dezajacomo Joice B Brigati Cristiano B Ferreira Maria IT Ferro Ana CR Silva Jesus A Ferro Julio CF Oliveira 《BMC microbiology》2009,9(1):12-17
Background
Citrus canker is a disease caused by the phytopathogens Xanthomonas citri subsp. citri, Xanthomonas fuscans subsp. aurantifolli and Xanthomonas alfalfae subsp. citrumelonis. The first of the three species, which causes citrus bacterial canker type A, is the most widely spread and severe, attacking all citrus species. In Brazil, this species is the most important, being found in practically all areas where citrus canker has been detected. Like most phytobacterioses, there is no efficient way to control citrus canker. Considering the importance of the disease worldwide, investigation is needed to accurately detect which genes are related to the pathogen-host adaptation process and which are associated with pathogenesis. 相似文献23.
João CR Cardoso Florbela A Vieira Ana S Gomes Deborah M Power 《BMC evolutionary biology》2010,10(1):135
Background
The secretin family is a pleotropic group of brain-gut peptides with affinity for class 2 G-protein coupled receptors (secretin family GPCRs) proposed to have emerged early in the metazoan radiation via gene or genome duplications. In human, 10 members exist and sequence and functional homologues and ligand-receptor pairs have been characterised in representatives of most vertebrate classes. Secretin-like family GPCR homologues have also been isolated in non-vertebrate genomes however their corresponding ligands have not been convincingly identified and their evolution remains enigmatic. 相似文献24.
25.
João CR Cardoso Edwin CJM de Vet Bruno Louro Greg Elgar Melody S Clark Deborah M Power 《BMC evolutionary biology》2007,7(1):221
Background:
Duplicated genes are common in vertebrate genomes. Their persistence is assumed to be either a consequence of gain of novel function (neofunctionalisation) or partitioning of the function of the ancestral molecule (sub-functionalisation). Surprisingly few studies have evaluated the extent of such modifications despite the numerous duplicated receptor and ligand genes identified in vertebrate genomes to date. In order to study the importance of function in the maintenance of duplicated genes, sea bream (Sparus auratus) PAC1 receptors, sequence homologues of the mammalian receptor specific for PACAP (Pituitary Adenylate Cyclase-Activating Polypeptide), were studied. These receptors belong to family 2 GPCRs and most of their members are duplicated in teleosts although the reason why both persist in the genome is unknown. 相似文献26.
Pungitore CR León LG García C Martín VS Tonn CE Padrón JM 《Bioorganic & medicinal chemistry letters》2007,17(5):1332-1335
The naturally occurring iridoid catalpol (1) is a Taq DNA polymerase inhibitor. However, its poor lipophilicity might account for the lack of biological activity against human solid tumor cell lines. The traditional prodrug approach by means of peracetylation of the free hydroxyl groups led to a compound, which showed a marginal growth inhibition against the most sensitive cell line A2780 (ovarian cancer). However, the formation of analogs bearing one to three silyl ether groups led to antiproliferative compounds against a panel of six human solid tumor cell lines, with GI50 values in the range 1.8-4.8 microM. Cell cycle studies revealed arrest in G0/G1 phase that is consistent with DNA polymerase inhibition. 相似文献
27.
Slawson EE Shaffer CD Malone CD Leung W Kellmann E Shevchek RB Craig CA Bloom SM Bogenpohl J Dee J Morimoto ET Myoung J Nett AS Ozsolak F Tittiger ME Zeug A Pardue ML Buhler J Mardis ER Elgin SC 《Genome biology》2006,7(2):R15-18
Background
Chromosome four of Drosophila melanogaster, known as the dot chromosome, is largely heterochromatic, as shown by immunofluorescent staining with antibodies to heterochromatin protein 1 (HP1) and histone H3K9me. In contrast, the absence of HP1 and H3K9me from the dot chromosome in D. virilis suggests that this region is euchromatic. D. virilis diverged from D. melanogaster 40 to 60 million years ago.Results
Here we describe finished sequencing and analysis of 11 fosmids hybridizing to the dot chromosome of D. virilis (372,650 base-pairs) and seven fosmids from major euchromatic chromosome arms (273,110 base-pairs). Most genes from the dot chromosome of D. melanogaster remain on the dot chromosome in D. virilis, but many inversions have occurred. The dot chromosomes of both species are similar to the major chromosome arms in gene density and coding density, but the dot chromosome genes of both species have larger introns. The D. virilis dot chromosome fosmids have a high repeat density (22.8%), similar to homologous regions of D. melanogaster (26.5%). There are, however, major differences in the representation of repetitive elements. Remnants of DNA transposons make up only 6.3% of the D. virilis dot chromosome fosmids, but 18.4% of the homologous regions from D. melanogaster; DINE-1 and 1360 elements are particularly enriched in D. melanogaster. Euchromatic domains on the major chromosomes in both species have very few DNA transposons (less than 0.4 %).Conclusion
Combining these results with recent findings about RNAi, we suggest that specific repetitive elements, as well as density, play a role in determining higher-order chromatin packaging. 相似文献28.
Assessing horizontal transfer of nifHDK genes in eubacteria: nucleotide sequence of nifK from Frankia strain HFPCcI3 总被引:2,自引:1,他引:1
Hirsch AM; McKhann HI; Reddy A; Liao J; Fang Y; Marshall CR 《Molecular biology and evolution》1995,12(1):16-27
The structural genes for nitrogenase, nifK, nifD, and nifH, are crucial for
nitrogen fixation. Previous phylogenetic analysis of the amino acid
sequence of nifH suggested that this gene had been horizontally transferred
from a proteobacterium to the gram-positive/cyanobacterial clade, although
the confounding effects of paralogous comparisons made interpretation of
the data difficult. An additional test of nif gene horizontal transfer
using nifD was made, but the NifD phylogeny lacked resolution. Here nif
gene phylogeny is addressed with a phylogenetic analysis of a third and
longer nif gene, nifK. As part of the study, the nifK gene of the key taxon
Frankia was sequenced. Parsimony and some distance analyses of the nifK
amino acid sequences provide support for vertical descent of nifK, but
other distance trees provide support for the lateral transfer of the gene.
Bootstrap support was found for both hypotheses in all trees; the nifK data
do not definitively favor one or the other hypothesis. A parsimony analysis
of NifH provides support for horizontal transfer in accord with previous
reports, although bootstrap analysis also shows some support for vertical
descent of the orthologous nifH genes. A wider sampling of taxa and more
sophisticated methods of phylogenetic inference are needed to understand
the evolution of nif genes. The nif genes may also be powerful phylogenetic
tools. If nifK evolved by vertical descent, it provides strong evidence
that the cyanobacteria and proteobacteria are sister groups to the
exclusion of the firmicutes, whereas 16S rRNA sequences are unable to
resolve the relationships of these three major eubacterial lineages.
相似文献
29.
Since gastrin and its related peptides are secreted by a minority population of widely dispersed cells in mamamalian tissues it has, in the past, been difficult to study the subcellular aspects of their secretion. From published reports (1, 2) it seemed possible that a satisfactory system for such studies might be provided by the skin of certain amphibians such as Xenopus laevis since in these tissues high concentrations of peptides such as caerulein exist, and there is some indication (3) that this, or a similar gastrin-like peptide, may be a dermal gland secretory product. We have therefore explored this possibility by studying the structure, secretory process, and secretory product of the most prominent non mucous type of gland in the skin of X. laevis. These studies clearly demonstrate that most, if not all, of the caerulein in which the skin is contained in secretion granules within the dermal glands and that its release can be specifically evoked by adrenergic stimulation. The release process by a holocrine mechanism expels all of the stored secretion onto the skin surface and thus for biosynthetic studies it should now be possible to synchronize the processes which lead to the replenishment of the peptide. 相似文献
30.
Zimmerman PA; Katholi CR; Wooten MC; Lang-Unnasch N; Unnasch TR 《Molecular biology and evolution》1994,11(3):384-392
Polymerase chain reaction (PCR) products were characterized for a repeated
sequence family (designated "O-150") of the human filarial parasite
Onchocerca volvulus. In phylogenetic inferences, the O-150 sequences
clustered into closely related groups, suggesting that concerted evolution
maintains sequence homology in this family. Using a novel mathematical
model based on a nested application of an analysis of variance, we
demonstrated that African rainforest and savannah strain parasite
populations are significantly different. In contrast, parasites collected
in the New World are indistinguishable from African savannah strains of O.
volvulus. This finding supports the hypothesis that onchocerciasis was
recently introduced into the New World, possibly as a result of the slave
trade.
相似文献