Major histocompatibility complex class I loci from the gray whale (Eschrichtius robustus)

Area of Science:

• * Marine Mammal Genetics
• * Evolutionary Immunology
• * Cetacean Genomics

Background:

• * The major histocompatibility complex class I (MHC-I) is crucial for immune response.
• * Investigating MHC-I variation in cetaceans provides insights into their evolutionary history and immune system.
• * The California gray whale (Eschrichtius robustus) is a key species for understanding mysticete (baleen whale) evolution.

Purpose of the Study:

• * To isolate and characterize MHC class I gene sequences from the California gray whale.
• * To investigate the genetic variation within the peptide-binding region of these MHC-I genes.
• * To compare gray whale MHC-I sequences with those of other mammals to infer phylogenetic relationships and evolutionary pressures.

Main Methods:

• * Isolation of DNA from California gray whale genomic samples.
• * Sequencing of exons encoding the peptide-binding region of MHC class I molecules.
• * Bioinformatic analysis of sequence variation and substitution patterns.

Main Results:

• * First report of mysticete MHC class I sequences, specifically from the California gray whale.
• * Identification of at least three distinct MHC-I loci in the gray whale.
• * Gray whale MHC-I sequences show greatest similarity to ungulate MHC-I, supporting cetacean phylogenetics.
• * Polymorphism patterns in the peptide-binding region suggest evolutionary selection, similar to other species.

Conclusions:

• * The study establishes a foundational dataset for gray whale MHC-I genetics.
• * Findings support the hypothesis of balancing selection acting on MHC-I in gray whales.
• * The genetic similarity to ungulates offers further evidence for cetacean evolutionary links.