Synteny

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In comparative genomics, synteny (a neologism meaning "on the same ribbon"; Greek: σύν, syn = along with + ταινία, tainiā = band) describes the preserved order of genes between related species. During evolution, chromosomal rearrangement occurs and hence even closely related species have different patterns of synteny. In cytogenetics and comparative genomics, the disruption of synteny is an indication of divergent evolution. Disruption of synteny is caused by chromosome rearrangement. These rearrangements may have a significant functional impact on the organism's phenotype. Evolutionary biologists use these disruptions of synteny to infer the evolutionary relationships between organisms.

In Drosophila, chromosome arms of various species tend to display almost absolute conservation of gene content, with very few duplicative transpositions and almost no translocations evident between current populations. Gene order on the chromosomes however is completely scrambled. 931 rearrangements were detected between D. melanogaster and D. pseudoobscura (the first sequenced genomes of this genus), almost all were inversions within chromosome arms (paracentric inversions).

Cytologeneticists use synteny to denote the occurrence of two or more genetic loci on the same chromosome. All genetic loci on one chromosome are said to be syntenic. Loci may appear to be unlinked by conventional genetic tests for linkage, but still be syntenic.

[edit] External Links

• Synteny server Server for Synteny Identification and Analysis of Genome Rearrangement—the Identification of synteny and calculating reversal distances.

• Comparative Maps NIH's National Library of Medicine NCBI link to Gene Homology resources, and Comparative Chromosome Maps of the Human, Mouse, and Rat.

• NCBI Home Page NIH's National Library of Medicine NCBI (National Center for Biotechnology Information) link to a tremendous number of resources.