Abstract
BackgroundThe Major Histocompatibility Complex (MHC) is a key component of the adaptive immune system of all vertebrates and consists of the most polymorphic genes known to date. Due to this complexity, however, MHC remains to be characterized in many species including any Neotropical cichlid fish. Neotropical crater lake cichlids are ideal models to study evolutionary processes as they display one of the most convincing examples of sympatric and repeated parallel radiation events within and among isolated crater lakes.ResultsHere, we characterized the genes of MHC class IIB chain of the Midas cichlid species complex (Amphilophus cf. citrinellus) including fish from five lakes in Nicaragua. We designed 19 new specific primers anchored in a stepwise fashion in order to detect all alleles present. We obtained 866 genomic DNA (gDNA) sequences from thirteen individuals and 756 additional sequences from complementary DNA (cDNA) of seven of those individuals. We identified 69 distinct alleles with up to 25 alleles per individual. We also found considerable intron length variation and mismatches of alleles detected in cDNA and gDNA suggesting that some loci have undergone pseudogenization. Lastly, we created a model of protein structure homology for each allele and identified their key structural components.ConclusionsOverall, the Midas cichlid has one of the most diverse repertoires of MHC class IIB genes known, which could serve as a powerful tool to elucidate the process of divergent radiations, colonization and speciation in sympatry.
Highlights
The Major Histocompatibility Complex (MHC) is a key component of the adaptive immune system of all vertebrates and consists of the most polymorphic genes known to date
Cloning, sequencing and MHC organization For a total of 13 individuals we obtained 867 genomic DNA (gDNA) and 756 complementary DNA (cDNA) sequences, all belonging to the MHC IIB
Taken altogether, MHC IIB genes in the Midas cichlid showed enormous richness in allele diversity and copy number
Summary
The Major Histocompatibility Complex (MHC) is a key component of the adaptive immune system of all vertebrates and consists of the most polymorphic genes known to date. Due to this complexity, MHC remains to be characterized in many species including any Neotropical cichlid fish. The function of the MHC molecules is to present short self and non-self peptides often derived from parasites and pathogens for recognition by T-lymphocytes [3]. This sets off the cascade of targeted immune defenses against those specific parasites and pathogens. There are two classical antigen presenting MHC molecules, MHC class I, that is expressed on all nucleated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
