ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    Genomic evidence for ameiotic evolution in the bdelloid rotifer Adineta vaga (2013)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2013-07-23
    Description: Loss of sexual reproduction is considered an evolutionary dead end for metazoans, but bdelloid rotifers challenge this view as they appear to have persisted asexually for millions of years. Neither male sex organs nor meiosis have ever been observed in these microscopic animals: oocytes are formed through mitotic divisions, with no reduction of chromosome number and no indication of chromosome pairing. However, current evidence does not exclude that they may engage in sex on rare, cryptic occasions. Here we report the genome of a bdelloid rotifer, Adineta vaga (Davis, 1873), and show that its structure is incompatible with conventional meiosis. At gene scale, the genome of A. vaga is tetraploid and comprises both anciently duplicated segments and less divergent allelic regions. However, in contrast to sexual species, the allelic regions are rearranged and sometimes even found on the same chromosome. Such structure does not allow meiotic pairing; instead, we find abundant evidence of gene conversion, which may limit the accumulation of deleterious mutations in the absence of meiosis. Gene families involved in resistance to oxidation, carbohydrate metabolism and defence against transposons are significantly expanded, which may explain why transposable elements cover only 3% of the assembled sequence. Furthermore, 8% of the genes are likely to be of non-metazoan origin and were probably acquired horizontally. This apparent convergence between bdelloids and prokaryotes sheds new light on the evolutionary significance of sex.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Flot, Jean-Francois -- Hespeels, Boris -- Li, Xiang -- Noel, Benjamin -- Arkhipova, Irina -- Danchin, Etienne G J -- Hejnol, Andreas -- Henrissat, Bernard -- Koszul, Romain -- Aury, Jean-Marc -- Barbe, Valerie -- Barthelemy, Roxane-Marie -- Bast, Jens -- Bazykin, Georgii A -- Chabrol, Olivier -- Couloux, Arnaud -- Da Rocha, Martine -- Da Silva, Corinne -- Gladyshev, Eugene -- Gouret, Philippe -- Hallatschek, Oskar -- Hecox-Lea, Bette -- Labadie, Karine -- Lejeune, Benjamin -- Piskurek, Oliver -- Poulain, Julie -- Rodriguez, Fernando -- Ryan, Joseph F -- Vakhrusheva, Olga A -- Wajnberg, Eric -- Wirth, Benedicte -- Yushenova, Irina -- Kellis, Manolis -- Kondrashov, Alexey S -- Mark Welch, David B -- Pontarotti, Pierre -- Weissenbach, Jean -- Wincker, Patrick -- Jaillon, Olivier -- Van Doninck, Karine -- England -- Nature. 2013 Aug 22;500(7463):453-7. doi: 10.1038/nature12326. Epub 2013 Jul 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉University of Namur, Department of Biology, URBE, Laboratory of Evolutionary Genetics and Ecology, 5000 Namur, Belgium. jean-francois.flot@ds.mpg.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23873043" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Gene Conversion/*genetics ; Gene Transfer, Horizontal/genetics ; Genome/*genetics ; Genomics ; Meiosis/genetics ; Models, Biological ; Reproduction, Asexual/*genetics ; Rotifera/*genetics ; Tetraploidy
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    Genome-Level Analysis of Selective Constraint without Apparent Sequence Conservation (2013)
    Oxford University Press
    Details
    Publication Date: 2013-03-17
    Description: Conservation of function can be accompanied by obvious similarity of homologous sequences which may persist for billions of years (Iyer LM, Leipe DD, Koonin EV, Aravind L. 2004. Evolutionary history and higher order classification of AAA+ ATPases. J Struct Biol. 146:11–31.). However, presumably homologous segments of noncoding DNA can also retain their ancestral function even after their sequences diverge beyond recognition (Fisher S, Grice EA, Vinton RM, Bessling SL, McCallion AS. 2006. Conservation of RET regulatory function from human to zebrafish without sequence similarity. Science 312:276–279.). To investigate this phenomenon at the genomic scale, we studied homologous introns in a quartet of insect species, and in a quartet of vertebrate species. Each quartet consisted of two pairs of moderately distant genomes, with a much larger evolutionary distance between the pairs. In both quartets, we found that introns that carry a regulatory segment or a conserved segment in the first pair tend to carry a conserved segment in the second pair, even though no similarity of these segments could be detected between the two pairs. Furthermore, introns from one pair that are preserved in the other pair tend to carry a conserved segment within the first pair, and be longer in the first pair, compared with the introns that were lost between pairs, even though no similarity between pairs could be detected in such preserved introns. These results indicate that selective constraint, presumably caused by conservation of the ancestral function, often persists even after the homologous DNA segments become unalignable.
    Electronic ISSN: 1759-6653
    Topics: Biology
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    Functional implications of splicing polymorphisms in the human genome (2013)
    Oxford University Press
    Details
    Publication Date: 2013-08-08
    Description: Proper splicing is often crucial for gene functioning and its disruption may be strongly deleterious. Nevertheless, even the essential for splicing canonical dinucleotides of the splice sites are often polymorphic. Here, we use data from The 1000 Genomes Project to study single-nucleotide polymorphisms (SNPs) in the canonical dinucleotides. Splice sites carrying SNPs are enriched in weakly expressed genes and in rarely used alternative splice sites. Genes with disrupted splice sites tend to have low selective constraint, and the splice sites disrupted by SNPs are less likely to be conserved in mouse. Furthermore, SNPs are enriched in splice sites whose effects on gene function are minor: splice sites located outside of protein-coding regions, in shorter exons, closer to the 3'-ends of proteins, and outside of functional protein domains. Most of these effects are more pronounced for high-frequency SNPs. Despite these trends, many of the polymorphic sites may still substantially affect the function of the corresponding genes. A number of the observed splice site-disrupting SNPs, including several high-frequency ones, were found among mutations described in OMIM.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Polymerase {zeta} Activity Is Linked to Replication Timing in Humans: Evidence from Mutational Signatures (2015)
    Oxford University Press
    Details
    Publication Date: 2015-11-20
    Description: Replication timing is an important determinant of germline mutation patterns, with a higher rate of point mutations in late replicating regions. Mechanisms underlying this association remain elusive. One of the suggested explanations is the activity of error-prone DNA polymerases in late-replicating regions. Polymerase zeta (pol ), an essential error-prone polymerase biased toward transversions, also has a tendency to produce dinucleotide mutations (DNMs), complex mutational events that simultaneously affect two adjacent nucleotides. Experimental studies have shown that pol is strongly biased toward GC-〉AA/TT DNMs. Using primate divergence data, we show that the GC-〉AA/TT pol mutational signature is the most frequent among DNMs, and its rate exceeds the mean rate of other DNM types by a factor of approximately 10. Unlike the overall rate of DNMs, the pol signature drastically increases with the replication time in the human genome. Finally, the pol signature is enriched in transcribed regions, and there is a strong prevalence of GC-〉TT over GC-〉AA DNMs on the nontemplate strand, indicating association with transcription. A recurrently occurring GC-〉TT DNM in HRAS and SOD1 genes causes the Costello syndrome and amyotrophic lateral sclerosis correspondently; we observe an approximately 1 kb long mutation hotspot enriched by transversions near these DNMs in both cases, suggesting a link between these diseases and pol activity. This study uncovers the genomic preferences of pol , shedding light on a novel cause of mutational heterogeneity along the genome.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    Bursts of nonsynonymous substitutions in HIV-1 evolution reveal instances of positive selection at conservative protein sites (2006)
    National Academy of Sciences
    Details
    Publication Date: 2006-12-12
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Complex Selection on Human Polyadenylation Signals Revealed by Polymorphism and Divergence Data (2016)
    Oxford University Press
    Details
    Publication Date: 2016-07-04
    Description: Polyadenylation is a step of mRNA processing which is crucial for its expression and stability. The major polyadenylation signal (PAS) represents a nucleotide hexamer that adheres to the AATAAA consensus sequence. Over a half of human genes have multiple cleavage and polyadenylation sites, resulting in a great diversity of transcripts differing in function, stability, and translational activity. Here, we use available whole-genome human polymorphism data together with data on interspecies divergence to study the patterns of selection acting on PAS hexamers. Common variants of PAS hexamers are depleted of single nucleotide polymorphisms (SNPs), and SNPs within PAS hexamers have a reduced derived allele frequency (DAF) and increased conservation, indicating prevalent negative selection; at the same time, the SNPs that "improve" the PAS (i.e., those leading to higher cleavage efficiency) have increased DAF, compared to those that "impair" it. SNPs are rarer at PAS of "unique" polyadenylation sites (one site per gene); among alternative polyadenylation sites, at the distal PAS and at exonic PAS. Similar trends were observed in DAFs and divergence between species of placental mammals. Thus, selection permits PAS mutations mainly at redundant and/or weakly functional PAS. Nevertheless, a fraction of the SNPs at PAS hexamers likely affect gene functions; in particular, some of the observed SNPs are associated with disease.
    Electronic ISSN: 1759-6653
    Topics: Biology
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Extraordinary Genetic Diversity in a Wood Decay Mushroom (2015)
    Oxford University Press
    Details
    Publication Date: 2015-09-22
    Description: Populations of different species vary in the amounts of genetic diversity they possess. Nucleotide diversity , the fraction of nucleotides that are different between two randomly chosen genotypes, has been known to range in eukaryotes between 0.0001 in Lynx lynx and 0.16 in Caenorhabditis brenneri . Here, we report the results of a comparative analysis of 24 haploid genotypes (12 from the United States and 12 from European Russia) of a split-gill fungus Schizophyllum commune . The diversity at synonymous sites is 0.20 in the American population of S. commune and 0.13 in the Russian population. This exceptionally high level of nucleotide diversity also leads to extreme amino acid diversity of protein-coding genes. Using whole-genome resequencing of 2 parental and 17 offspring haploid genotypes, we estimate that the mutation rate in S. commune is high, at 2.0 x 10 –8 (95% CI: 1.1 x 10 –8 to 4.1 x 10 –8 ) per nucleotide per generation. Therefore, the high diversity of S. commune is primarily determined by its elevated mutation rate, although high effective population size likely also plays a role. Small genome size, ease of cultivation and completion of the life cycle in the laboratory, free-living haploid life stages and exceptionally high variability of S. commune make it a promising model organism for population, quantitative, and evolutionary genetics.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Strong Mutational Bias Toward Deletions in the Drosophila melanogaster Genome Is Compensated by Selection (2013)
    Oxford University Press
    Details
    Publication Date: 2013-03-16
    Description: Insertions and deletions (collectively indels) obviously have a major impact on genome evolution. However, before large-scale data on indel polymorphism became available, it was difficult to estimate the strength of selection acting on indel mutations. Here, we analyze indel polymorphism and divergence in different compartments of the Drosophila melanogaster genome: exons, introns of different lengths, and intergenic regions. Data on low-frequency polymorphisms indicate that 0.036–0.039 short (1–30 nt) insertion mutations and 0.085–0.092 short deletion mutations, with mean lengths 3.23 and 4.78, respectively, occur per single-nucleotide substitution. The excess of short deletion over short insertion mutations implies that indel mutations of these lengths should lead to a loss of approximately 0.30 nt per single-nucleotide replacement. However, polymorphism and divergence data show that this deletion bias is almost completely compensated by selection: Negative selection is stronger against deletions, whereas insertions are more likely to be favored by positive selection. Among the inframe low-frequency polymorphic mutations in exons, long introns, and intergenic regions, selection prevents a larger fraction of deletions (80–87%, depending on the type of the compartment) than of insertions (70–82%) or single-nucleotide substitutions (49–73%), from reaching high frequencies. The corresponding fractions were the lowest in short introns: 66%, 47%, and 15%, respectively, consistent with the weakest selective constraint in them. The McDonald–Kreitman test shows that 32–46% of the deletions and 60–73% of the insertions that were fixed in the recent evolution of D. melanogaster are adaptive, whereas this fraction is only 0–29% for single-nucleotide substitutions.
    Electronic ISSN: 1759-6653
    Topics: Biology
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Negative selection in humans and fruit flies involves synergistic epistasis (2017)
    Sohail, M., Vakhrusheva, O. A., Sul, J. H., Pulit, S. L., Francioli, L. C., Genome of the Netherlands Consortium, Alzheimers Disease Neuroimaging Initiative, van den Berg, L. H., Veldink, J. H., de Bakker, P. I. W., Bazykin, G. A., Kondrashov, A. S., Sunyaev, S. R., Menelaou, van Dijk, Palamara, Elbers, Neerincx, Ye, Guryev, Kloosterman, Deelen, Abdellaoui, van Leeuwen, van Oven, Vermaat, Li, Laros, Karssen, Kanterakis, Amin, Hottenga, Lameijer, Kattenberg, Dijkstra, Byelas, van Setten, van Schaik, Bot, Nijman, Renkens, Marschall, Schnhuth, Hehir-Kwa, Handsaker, Polak, Vuzman, Hormozdiari, van Enckevort, Mei, Koval, Moed, Joeri van der Velde, Rivadeneira, Estrada, Medina-Gomez, Isaacs, McCarroll, Beekman, de Craen, Suchiman, Hofman, Oostra, Uitterlinden, Willemsen, Life; Lines Cohort Study, Platteel, Pitts, Potluri, Sundar, Cox, den Dunnen, Stoneking, de Knijff, Kayser, Li, Li, Du, Chen, Cao, Li, Cao, Wang, Bovenberg, Peer, Slagboom, van Duijn, Boomsma, van Ommen, Swertz, Wijmenga
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2017-05-05
    Description: Negative selection against deleterious alleles produced by mutation influences within-population variation as the most pervasive form of natural selection. However, it is not known whether deleterious alleles affect fitness independently, so that cumulative fitness loss depends exponentially on the number of deleterious alleles, or synergistically, so that each additional deleterious allele results in a larger decrease in relative fitness. Negative selection with synergistic epistasis should produce negative linkage disequilibrium between deleterious alleles and, therefore, an underdispersed distribution of the number of deleterious alleles in the genome. Indeed, we detected underdispersion of the number of rare loss-of-function alleles in eight independent data sets from human and fly populations. Thus, selection against rare protein-disrupting alleles is characterized by synergistic epistasis, which may explain how human and fly populations persist despite high genomic mutation rates.
    Keywords: Genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Weak Negative and Positive Selection and the Drift Load at Splice Sites (2014)
    Oxford University Press
    Details
    Publication Date: 2014-06-27
    Description: Splice sites (SSs) are short sequences that are crucial for proper mRNA splicing in eukaryotic cells, and therefore can be expected to be shaped by strong selection. Nevertheless, in mammals and in other intron-rich organisms, many of the SSs often involve nonconsensus (Nc), rather than consensus (Cn), nucleotides, and beyond the two critical nucleotides, the SSs are not perfectly conserved between species. Here, we compare the SS sequences between primates, and between Drosophila fruit flies, to reveal the pattern of selection acting at SSs. Cn-to-Nc substitutions are less frequent, and Nc-to-Cn substitutions are more frequent, than neutrally expected, indicating, respectively, negative and positive selection. This selection is relatively weak (1 〈 |4 N e s | 〈 4), and has a similar efficiency in primates and in Drosophila. Within some nucleotide positions, the positive selection in favor of Nc-to-Cn substitutions is weaker than the negative selection maintaining already established Cn nucleotides; this difference is due to site-specific negative selection favoring current Nc nucleotides. In general, however, the strength of negative selection protecting the Cn alleles is similar in magnitude to the strength of positive selection favoring replacement of Nc alleles, as expected under the simple nearly neutral turnover. In summary, although a fraction of the Nc nucleotides within SSs is maintained by selection, the abundance of deleterious nucleotides in this class suggests a substantial genome-wide drift load.
    Electronic ISSN: 1759-6653
    Topics: Biology
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...