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Dani?l P Melters Keith R Bradnam Hugh A Young Natalie Telis Michael R May J Graham Ruby Robert Sebra Paul Peluso John Eid David Rank José Fernando Garcia Joseph L DeRisi Timothy Smith Christian Tobias Jeffrey Ross-Ibarra Ian Korf Simon WL Chan 《Genome biology》2013,14(1):R10
Background
Centromeres are essential for chromosome segregation, yet their DNA sequences evolve rapidly. In most animals and plants that have been studied, centromeres contain megabase-scale arrays of tandem repeats. Despite their importance, very little is known about the degree to which centromere tandem repeats share common properties between different species across different phyla. We used bioinformatic methods to identify high-copy tandem repeats from 282 species using publicly available genomic sequence and our own data.Results
Our methods are compatible with all current sequencing technologies. Long Pacific Biosciences sequence reads allowed us to find tandem repeat monomers up to 1,419 bp. We assumed that the most abundant tandem repeat is the centromere DNA, which was true for most species whose centromeres have been previously characterized, suggesting this is a general property of genomes. High-copy centromere tandem repeats were found in almost all animal and plant genomes, but repeat monomers were highly variable in sequence composition and length. Furthermore, phylogenetic analysis of sequence homology showed little evidence of sequence conservation beyond approximately 50 million years of divergence. We find that despite an overall lack of sequence conservation, centromere tandem repeats from diverse species showed similar modes of evolution.Conclusions
While centromere position in most eukaryotes is epigenetically determined, our results indicate that tandem repeats are highly prevalent at centromeres of both animal and plant genomes. This suggests a functional role for such repeats, perhaps in promoting concerted evolution of centromere DNA across chromosomes. 相似文献6.
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Marsin S McGovern S Ehrlich SD Bruand C Polard P 《The Journal of biological chemistry》2001,276(49):45818-45825
Primosomes are nucleoprotein assemblies designed for the activation of DNA replication forks. Their primary role is to recruit the replicative helicase onto single-stranded DNA. The "replication restart" primosome, defined in Escherichia coli, is involved in the reactivation of arrested replication forks. Binding of the PriA protein to forked DNA triggers its assembly. PriA is conserved in bacteria, but its primosomal partners are not. In Bacillus subtilis, genetic analysis has revealed three primosomal proteins, DnaB, DnaD, and DnaI, that have no obvious homologues in E. coli. Interestingly, they are involved in primosome function both at arrested replication forks and at the chromosomal origin. Our biochemical analysis of the DnaB and DnaD proteins unravels their role in primosome assembly. They are both multimeric and bind individually to DNA. Furthermore, DnaD stimulates DnaB binding activities. DnaD alone and the DnaD/DnaB pair interact specifically with PriA of B. subtilis on several DNA substrates. This suggests that the nucleoprotein assembly is sequential in the PriA, DnaD, DnaB order. The preferred DNA substrate mimics an arrested DNA replication fork with unreplicated lagging strand, structurally identical to a product of recombinational repair of a stalled replication fork. 相似文献
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McGovern TM 《Proceedings. Biological sciences / The Royal Society》2003,270(1532):2517-2522
Plastic reproductive allocation may allow individuals to maximize their fitness when conditions vary. Mate availability is one condition that may determine the fitness of an individual's allocation strategy. Using a variety of methods, I detected evidence of plastic allocation to asexual (clonal) reproduction in response to mate availability in the brittle star Ophiactis savignyi. There were more mature individuals in populations in which both sexes were present, and clones from these populations had fewer clone-mates than clones from single-sex populations. Animals placed with mates in a field experiment divided less frequently than animals without a mate. These findings demonstrate that animals reduce their allocation to asexual reproduction when mates are present and when a loss of fecundity associated with cloning would decrease offspring production. This plasticity is probably adaptive because it maximizes sexual-reproductive potential when fertilization is more likely, but maximizes survival of the clone when mates are absent and gametes are unlikely to be converted to offspring. 相似文献
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Cavalieri D McGovern PE Hartl DL Mortimer R Polsinelli M 《Journal of molecular evolution》2003,57(Z1):S226-S232
Saccharomyces cerevisiae is the principal yeast used in modern fermentation processes, including winemaking, breadmaking, and brewing. From residue present inside one of the earliest known wine jars from Egypt, we have extracted, amplified, and sequenced ribosomal DNA from S. cerevisiae. These results indicate that this organism was probably responsible for wine fermentation by at least 3150 B.C. This inference has major implications for the evolution of bread and beer yeasts, since it suggests that S. cerevisiae yeast, which occurs naturally on the surface bloom of grapes, was also used as an inoculum to ferment cereal products. 相似文献