Duplicated paralogous genes subject to positive selection in the genome of Trypanosoma brucei.
BACKGROUND
Whole genome studies have highlighted duplicated genes as important substrates for adaptive evolution. We have investigated adaptive evolution in this class of genes in the human parasite Trypanosoma brucei, as indicated by the ratio of non-synonymous (amino-acid changing) to synonymous (amino acid retaining) nucleotide substitution rates.


RESULTS
We have identified duplicated genes that are most rapidly evolving in this important human parasite. This is the first attempt to investigate adaptive evolution in this species at the codon level. We identify 109 genes within 23 clusters of paralogous gene expansions to be subject to positive selection.


CONCLUSIONS
Genes identified include surface antigens in both the mammalian and insect host life cycle stage suggesting that competitive interaction is not solely with the adaptive immune system of the mammalian host. Also surface transporters related to drug resistance and genes related to developmental progression are detected. We discuss how adaptive evolution of these genes may highlight lineage specific processes essential for parasite survival. We also discuss the implications of adaptive evolution of these targets for parasite biology and control.
Emes
Richard D
RD
Institute for Science and Technology in Medicine, Keele University, Stoke-on-Trent, United Kingdom. r.d.emes@hfac.keele.ac.uk
Yang
Ziheng
Z
D000262:Adenylyl Cyclases / Q000235:genetics; D026905:Amino Acid Transport Systems / Q000235:genetics; D000818:Animals; D019143:Evolution, Molecular; D020440:Gene Duplication; D018503:Genome, Protozoan; D008562:Membrane Glycoproteins / Q000235:genetics; D033703:Nucleoside Transport Proteins / Q000235:genetics; D015800:Protozoan Proteins / Q000235:genetics; D012641:Selection, Genetic; D014346:Trypanosoma brucei brucei / Q000235:genetics*
D026905:Amino Acid Transport Systems; D008562:Membrane Glycoproteins; D033703:Nucleoside Transport Proteins; D015800:Protozoan Proteins; C444719:adenosine transporter; C053277:procyclic acidic repetitive protein, Trypanosoma; D000262:Adenylyl Cyclases