Display Settings:

Format

Send to:

Choose Destination
BMC Evol Biol. 2008 Apr 11;8:108. doi: 10.1186/1471-2148-8-108.

Consistent and contrasting properties of lineage-specific genes in the apicomplexan parasites Plasmodium and Theileria.

Author information

  • 1Department of Genetics, University of Georgia, Athens, GA 30602, USA. chkuo@uga.edu

Abstract

BACKGROUND:

Lineage-specific genes, the genes that are restricted to a limited subset of related organisms, may be important in adaptation. In parasitic organisms, lineage-specific gene products are possible targets for vaccine development or therapeutics when these genes are absent from the host genome.

RESULTS:

In this study, we utilized comparative approaches based on a phylogenetic framework to characterize lineage-specific genes in the parasitic protozoan phylum Apicomplexa. Genes from species in two major apicomplexan genera, Plasmodium and Theileria, were categorized into six levels of lineage specificity based on a nine-species phylogeny. In both genera, lineage-specific genes tend to have a higher level of sequence divergence among sister species. In addition, species-specific genes possess a strong codon usage bias compared to other genes in the genome. We found that a large number of genus- or species-specific genes are putative surface antigens that may be involved in host-parasite interactions. Interestingly, the two parasite lineages exhibit several notable differences. In Plasmodium, the (G + C) content at the third codon position increases with lineage specificity while Theileria shows the opposite trend. Surface antigens in Plasmodium are species-specific and mainly located in sub-telomeric regions. In contrast, surface antigens in Theileria are conserved at the genus level and distributed across the entire lengths of chromosomes.

CONCLUSION:

Our results provide further support for the model that gene duplication followed by rapid divergence is a major mechanism for generating lineage-specific genes. The result that many lineage-specific genes are putative surface antigens supports the hypothesis that lineage-specific genes could be important in parasite adaptation. The contrasting properties between the lineage-specific genes in two major apicomplexan genera indicate that the mechanisms of generating lineage-specific genes and the subsequent evolutionary fates can differ between related parasite lineages. Future studies that focus on improving functional annotation of parasite genomes and collection of genetic variation data at within- and between-species levels will be important in facilitating our understanding of parasite adaptation and natural selection.

PMID:
18405380
[PubMed - indexed for MEDLINE]
PMCID:
PMC2330040
Free PMC Article

Images from this publication.See all images (8)Free text

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for BioMed Central Icon for PubMed Central
    Loading ...
    Write to the Help Desk