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分子遗传学阅读文献:B染色体和多倍体

已有 7005 次阅读 2008-8-28 17:21 |个人分类:科学感想|系统分类:科研笔记| 多倍体, 分子遗传学阅读文献, 分子遗传学阅读文献, B染色体

The chromosome number in humans

 

Gartler SM. The chromosome number in humans: a brief history. Nat Rev Genet. 2006 Aug; 7 (8): 655-60

 

Following the rediscovery of Mendel's work in 1900, the field of genetics advanced rapidly. Human genetics, however, lagged behind; this was especially noticeable in cytogenetics, which was already a mature discipline in experimental forms in the 1950s. We did not know the correct human chromosome number in 1955, let alone were we able to detect a chromosomal abnormality. In 1956 a discovery was reported that markedly altered human cytogenetics and genetics. The following is an analysis of that discovery.

The chromosome number in humans

B chromosomes in plants: escapees from the A chromosome genome?

 

Jones N, Houben A. B chromosomes in plants: escapees from the A chromosome genome? Trends Plant Sci. 2003 Sep; 8 (9): 417-23

 

B chromosomes are dispensable elements that do not recombine with the A chromosomes of the regular complement and that follow their own evolutionary track. In some cases, they are known to be nuclear parasites with autonomous modes of inheritance, exploiting "drive" to ensure their survival in populations. Their "selfishness" brings them into conflict with their host nuclear genome and generates a host-parasite relationship, with anti-B-chromosome genes working to ameliorate the worst of their excesses in depriving their hosts of genetic resources. Molecular studies are homing in on their sequence organization to give us an insight into the origin and evolution of these enigmatic chromosomes, which are, with rare exceptions, without active genes. 

B chromosomes in plants

The advantages and disadvantages of being polyploidy

 

Comai L. The advantages and disadvantages of being polyploid. Nat Rev Genet. 2005 Nov; 6 (11): 836-46

 

Polyploids - organisms that have multiple sets of chromosomes - are common in certain plant and animal taxa, and can be surprisingly stable. The evidence that has emerged from genome analyses also indicates that many other eukaryotic genomes have a polyploid ancestry, suggesting that both humans and most other eukaryotes have either benefited from or endured polyploidy. Studies of polyploids soon after their formation have revealed genetic and epigenetic interactions between redundant genes. These interactions can be related to the phenotypes and evolutionary fates of polyploids. Here, I consider the advantages and challenges of polyploidy, and its evolutionary potential.

 The advantages and disadvantages of being polyploidy

 

Breaking down taxonomic barriers in polyploidy research

 

Mable BK. Breaking down taxonomic barriers in polyploidy research. Trends Plant Sci. 2003 Dec; 8 (12): 582-90

 

Polyploidy is important in the evolutionary history of plants, and it has played a crucial role in shaping the genome structures of all eukaryotes. New and rapidly improving techniques in genomics, cytogenetics and molecular ecology have resulted in a dramatic increase in publications about duplicate genes, genome rearrangements and detection of ancient duplication events. Similarly, research associated with the origins of polyploidy, its persistence in natural populations and the resulting ecological consequences is receiving more attention. Although polyploidy research has been conducted using both animal and plant systems, inferences based on cross-disciplinary comparisons have been rare. Here, I review recent developments in the field in both plants and animals, emphasizing the benefits of communication between the two groups.

Breaking down taxonomic barriers in polyploidy research

Polyploidy and genome evolution in plants

 

Adams KL, Wendel JF. Polyploidy and genome evolution in plants. Curr Opin Plant Biol. 2005 Apr; 8 (2): 135-41

 

Genome doubling (polyploidy) has been and continues to be a pervasive force in plant evolution. Modern plant genomes harbor evidence of multiple rounds of past polyploidization events, often followed by massive silencing and elimination of duplicated genes. Recent studies have refined our inferences of the number and timing of polyploidy events and the impact of these events on genome structure. Many polyploids experience extensive and rapid genomic alterations, some arising with the onset of polyploidy. Survivorship of duplicated genes are differential across gene classes, with some duplicate genes more prone to retention than others. Recent theory is now supported by evidence showing that genes that are retained in duplicate typically diversify in function or undergo subfunctionalization. Polyploidy has extensive effects on gene expression, with gene silencing accompanying polyploid formation and continuing over evolutionary time.

Polyploidy and genome evolution in plants

 



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