Publication

Multi-Locus Major Histocompatibility Complex Class IIB and Parasite Diversity in the Rio Grande Silvery Minnow

URL: https://webapps.usgs.gov/mrgescp/documents/Osborne%20and%20Turner_2009_Collaborative%20Research%20and%20Monitoring%20Evaluation%20of%20the%20RGSM%20Health%20in%20Relation%20to%20Changes%20in%20Water%20Quality%2C%20Pathogens%20and%20Other%20Environ....pdf

Date: 2009/01/30

Author(s): Osborne M.J., Turner T.F.

Publication: Report prepared for U.S. Fish and Wildlife Service, 43 p.

Abstract:

Long-term persistence of species depends partially on avoiding loss of genetic variation (Hedrick et al. 1996). This variation forms the basis of a species’ ability to adapt and respond to changing environments. For example, genetic variation of genes involved with immunity serves as the foundation of an individual’s response to disease pressures. Variation at immune genes is especially important for aquatic species, whose chemical and microbial environment is impacted heavily by humans, which may increase their risk of exposure to pathogens (De Swart et al. 1996; Harvell et al. 1999). In this portion of the fish health study we characterized and measured diversity at genes of the major histocompatibility complex (MHC) Class IIβ in the Rio Grande silvery minnow, Hybognathus amarus. These data were used to examine the relationship between MHC variation and pathogen diversity. Major findings of this study were:

• Seventy-two different MHC alleles were identified based on MHC Class IIβ Exon two cDNA sequences and all alleles shared conserved features of classical MHC Class IIβ.
• Three divergent groups of alleles were identified on the basis of phylogenetic analysis.
• The expression of Hyam-DAB1*05 was associated with lighter Costia spp. infection whilst expression of Hyam-DAB2*06 was associated with heavier Costia spp. infection. Expression of Hyam-DAB1*13 was associated with heavier Apiosoma infection. No relationship was detected between presence or absence of Hyam-DAB1*03 or HyamDAB2*04 an infection with particular species.
• No association between gill parasite diversity (number of species per individual) or abundance and MHC diversity (number of MHC alleles per fish) was detected.
• No association was detected between pathogen diversity or abundance and the number of MHC allelic groups expressed by individuals.
• Parasite and bacterial species diversity and abundance also differed spatially.