Abstract
BackgroundGoats (Capra hircus), one of the first domesticated species, are economically important for milk and meat production, and their broad geographical distribution reflects their successful adaptation to diverse environmental conditions. Despite the relevance of this species, the genetic research on the goat traits is limited compared to other domestic species. Thanks to the latest goat reference genomic sequence (ARS1), which is considered to be one of the most continuous assemblies in livestock, we deduced the genomic structure of the T cell receptor beta (TRB) and gamma (TRG) loci in this ruminant species.ResultsOur analyses revealed that although the organization of the goat TRB locus is broadly similar to that of the other artiodactyl species, with three in-tandem D-J-C clusters located at the 3′ end, a complex and extensive series of duplications have occurred in the V genes at the 5′ end, leading to a marked expansion in the number of the TRBV genes. This phenomenon appears to be a feature of the ruminant lineage since similar gene expansions have also occurred in sheep and cattle.Likewise, the general organization of the goat TRG genes is typical of ruminant species studied so far, with two paralogous TRG loci, TRG1 and TRG2, located in two distinct and distant positions on the same chromosome as result of a split in the ancestral locus. Each TRG locus consists of reiterated V-J-J-C cassettes, with the goat TRG2 containing an additional cassette relative to the corresponding sheep and cattle loci.ConclusionsTaken together, these findings demonstrate that strong evolutionary pressures in the ruminant lineage have selected for the development of enlarged sets of TRB and TRG genes that contribute to a diverse T cell receptor repertoire. However, differences observed among the goat, sheep and cattle TRB and TRG genes indicate that distinct evolutionary histories, with independent expansions and/or contractions, have also affected each ruminant species.
Highlights
Goats (Capra hircus), one of the first domesticated species, are economically important for milk and meat production, and their broad geographical distribution reflects their successful adaptation to diverse environmental conditions
Using the corresponding sheep genomic sequences as reference, we retrieved from the Capra hircus chromosome 4 genomic scaffold (GenBank ID: CM004565) the T cell receptor beta (TRB) and TRG genomic regions and established their structures
The general structural organization of the goat TRB locus is conserved with respect to the other artiodactyl species [11,12,13,14, 16, 17], with a library of TRBV genes positioned at the 5′ end of three D-J-C clusters, that is followed by a single TRBV gene located at the 3′ end in an inverted transcriptional orientation (Fig. 1)
Summary
Goats (Capra hircus), one of the first domesticated species, are economically important for milk and meat production, and their broad geographical distribution reflects their successful adaptation to diverse environmental conditions. Ruminant species are the most efficient herbivores and are distributed across diverse territories in terms of latitude (from tropical to arctic regions), altitude (from plains to plateaus) and habitat (from deserts to rainforests). Beyond their adaptability, these species show recognizable divergent phenotypes, including distinct morphological characteristics in the headgear (e.g., ossicones in giraffids, antlers in cervids and horns in bovids) [1] and variations in body size, which ranges from 2 kg (lesser deer) to 1200 Kg (giraffa and buffalo) [2]. The ruminant species have 10 or more lysozyme C genes, while most mammals have only one or a few lysozyme C genes [4, 5]
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
