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51.
Tumor hypoxia may be an indicator of poor survival in cancer patients. Thus, an understanding of the molecular mechanism responsible for hypoxic tumor selection is essential to gain further insight into tumor biology. Our aim in this study was to investigate whether hypoxia-responsive GLTSCR2 contributes to death resistance and increased invasiveness of hypoxia-selected glioblastoma cells. We found that repeated hypoxia downregulates p53-upstream regulator, GLTSCR2, which resulted in increased death resistance and invasive potential of glioblastoma cells. Restoration of GLTSCR2 expression suppressed the malignant potential of hypoxia-selected cells. Our results indicate that GLTSCR2 participates in hypoxia-induced malignant potential. 相似文献
52.
Natural populations are confronted with multiple selection pressures resulting in a mosaic of environmental stressors at the landscape level. Identifying the genetic underpinning of adaptation to these complex selection environments and assigning causes of natural selection within multidimensional selection regimes in the wild is challenging. The water flea Daphnia is a renowned ecological model system with its well-documented ecology, the possibility to analyse subfossil dormant egg banks and the short generation time allowing an experimental evolution approach. Capitalizing on the strengths of this model system, we here link candidate genome regions to three selection pressures, known to induce micro-evolutionary responses in Daphnia magna: fish predation, parasitism and land use. Using a genome scan approach in space, time and experimental evolution trials, we provide solid evidence of selection at the genome level under well-characterized environmental gradients in the wild and identify candidate genes linked to the three environmental stressors. Our study reveals differential selection at the genome level in Daphnia populations and provides evidence for repeatable patterns of local adaptation in a geographic mosaic of environmental stressors fuelled by standing genetic variation. Our results imply high evolutionary potential of local populations, which is relevant to understand the dynamics of trait changes in natural populations and their impact on community and ecosystem responses through eco-evolutionary feedbacks. 相似文献
53.
The intra- and interspecific diversity of avian beak morphologies is one of the most compelling examples for the power of natural selection acting on a morphological trait. The development and diversification of the beak have also become a textbook example for evolutionary developmental biology, and variation in expression levels of several genes is known to causally affect beak shape. However, until now, no genomic polymorphisms have been identified, which are related to beak morphology in birds. QTL mapping does reveal the location of causal polymorphisms, albeit with poor spatial resolution. Here, we estimate heritability and genetic correlations for beak length, depth and width and perform a QTL linkage analysis for these traits based on 1404 informative single-nucleotide polymorphisms genotyped in a four-generation pedigree of 992 captive zebra finches (Taeniopygia guttata). Beak size, relative to body size, was sexually dimorphic (larger in males). Heritability estimates ranged from 0.47 for beak length to 0.74 for beak width. QTL mapping revealed four to five regions of significant or suggestive genome-wide linkage for each of the three beak dimensions (nine different regions in total). Eight out of 11 genes known to influence beak morphology are located in these nine peak regions. Five QTL do not cover known candidates demonstrating that yet unknown genes or regulatory elements may influence beak morphology in the zebra finch. 相似文献
54.
Simple sequence repeats (SSRs) can be derived from the complete genome sequence. These markers are important for gene
mapping as well as marker-assisted selection (MAS). To develop SSRs for cotton gene mapping, we selected the complete genome
sequence of Gossypium raimondii, which consisted of 4447 non-redundant scaffolds. Out of 775.2 Mb sequence examined, a total of
136,345 microsatellites were identified with a density of 5.69 kb per SSR in the G. raimondii genome leading to development of
112,177 primer pairs. The distributions of SSRs in the genome were non-random. Among the different motifs ranging from 1 to 6
bp, penta-nucleotide repeats were most abundant (30.5%), followed by tetra-nucleotide repeats (18.2%) and di-nucleotide repeats
(16.9%). Among all identified 457 motif types, the most frequently occurring repeat motifs were poly-AT/TA, which accounted for
79.8% of the total di-nt SSRs, followed by AAAT/TTTA with 51.5% of the total tetra-nucleotede. Further, 18,834 microsatellites
were detected from the protein-coding genes, and the frequency of gene containing SSRs was 46.0% in 40,976 genes of G. raimondii.
These genome-based SSRs developed in the present study will lay the groundwork for developing large numbers of SSR markers
for genetic mapping, gene discovery, genetic diversity analysis, and MAS breeding in cotton. 相似文献
55.
56.
Susanne Schmitt Peter Tsai James Bell Jane Fromont Micha Ilan Niels Lindquist Thierry Perez Allen Rodrigo Peter J Schupp Jean Vacelet Nicole Webster Ute Hentschel Michael W Taylor 《The ISME journal》2012,6(3):564-576
Marine sponges are well known for their associations with highly diverse, yet very specific and often highly similar microbiota. The aim of this study was to identify potential bacterial sub-populations in relation to sponge phylogeny and sampling sites and to define the core bacterial community. 16S ribosomal RNA gene amplicon pyrosequencing was applied to 32 sponge species from eight locations around the world''s oceans, thereby generating 2567 operational taxonomic units (OTUs at the 97% sequence similarity level) in total and up to 364 different OTUs per sponge species. The taxonomic richness detected in this study comprised 25 bacterial phyla with Proteobacteria, Chloroflexi and Poribacteria being most diverse in sponges. Among these phyla were nine candidate phyla, six of them found for the first time in sponges. Similarity comparison of bacterial communities revealed no correlation with host phylogeny but a tropical sub-population in that tropical sponges have more similar bacterial communities to each other than to subtropical sponges. A minimal core bacterial community consisting of very few OTUs (97%, 95% and 90%) was found. These microbes have a global distribution and are probably acquired via environmental transmission. In contrast, a large species-specific bacterial community was detected, which is represented by OTUs present in only a single sponge species. The species-specific bacterial community is probably mainly vertically transmitted. It is proposed that different sponges contain different bacterial species, however, these bacteria are still closely related to each other explaining the observed similarity of bacterial communities in sponges in this and previous studies. This global analysis represents the most comprehensive study of bacterial symbionts in sponges to date and provides novel insights into the complex structure of these unique associations. 相似文献
57.
Yáñez JM González R Angulo J Vidal R Santos JL Martínez V 《Molecular ecology resources》2008,8(6):1442-1444
The emu (Dromaius novaehollandiae), a member of ratite family, is native to Australia and has been introduced to other countries worldwide. In this work, 10 polymorphic microsatellite loci were isolated and characterized for emu from public sequences. Polymorphism was surveyed in 22 individuals from two different populations kept in captivity. Between two and 11 alleles were found per locus, and the observed heterozygosity ranged from 0.05 to 0.85, in accordance with expectations. These markers will be useful as tools for detecting levels of genetic variation, reconstructing pedigrees (for quantitative genetic analysis) and identifying markers associated to fitness traits in emu populations. 相似文献
58.
利用Peri,C 语言编写了鉴定和分析简单重复序列的一系列程序,在全基因组水平上分析了拟南芥(Arabidopsisthaliana L.)简单重复序列的分布及简单重复序列和基因的关系.共发现5 652个简单重复序列(≥20bp),大约每20.6kb有1个简单重复序列.拟南芥各染色体之间简单重复序列的密度基本一致.拟南芥的27 480条编码序列中,只有677条编码序列含有725个简单重复序列,其中的3碱基简单重复序列多数对应的是小的亲水性的氨基酸.在拟南芥和水稻(Oryza sativa L.)第4号染色体的高度保守的基因中,简单重复序列却并不保守.通过比较拟南芥和水稻之间简单重复序列的差异,推论出:水稻的全基因组和基因中简单重复序列的密度都比拟南芥大,这可能是水稻基因组序列比拟南芥大的原因之一,水稻基因组中0.21%来自简单重复序列,而拟南芥中只有0.13%;不但不同物种的基因组对简单重复序列的偏好性不同,而且不同物种的基因对简单重复序列的偏好性也不同.在水稻和拟南芥中部发现了一些嵌套性的卫星序列. 相似文献
59.
Maria Luisa Brandi Luigi Gennari Marco Matucci Cerinic Lucia Becherini Alberto Falchetti Laura Masi Carlo Gennari Jean-Yves Reginster 《Arthritis research & therapy》2001,3(5):270-11
Osteoarthritis and osteoporosis are the two most common age-related chronic disorders of articular joints and skeleton, representing
a major public health problem in most developed countries. Apart from being influenced by environmental factors, both disorders
have a strong genetic component, and there is now considerable evidence from large population studies that these two disorders
are inversely related. Thus, an accurate analysis of the genetic component of one of these two multifactorial diseases may
provide data of interest for the other. However, the existence of confounding factors must always be borne in mind in interpreting
the genetic analysis. In addition, each patient must be given an accurate clinical evaluation, including family history, history
of drug treatments, lifestyle, and environment, in order to reduce the background bias. Here, we review the impact of recent
work in molecular genetics suggesting that powerful molecular biology techniques will soon make possible both a rapid accumulation
of data on the genetics of both disorders and the development of novel diagnostic, prognostic, and therapeutic approaches. 相似文献
60.
Andrew J. Lowe Alexandra E. Jones Alan F. Raybould Martin Trick Carolyn L. Moule Keith J. Edwards 《Molecular ecology resources》2002,2(1):7-11
We present a new set of 12 highly polymorphic simple sequence repeat primer sequences for use with Brassica species. These new primers, and four from A.K.S. SzewcMcFadden and colleagues, were tested in four Brassica species (B. rapa, B. napus, B. oleracea and B. nigra). Most primers successfully amplified products within all species and were polymorphic. Due to the risk of gene flow from GM oilseed rape to its wild relatives, hybrid formation in the Brassicaceae is of great interest. We identify six primer pairs as specific to the A, B or C genomes that could be used to identify such hybrids. 相似文献