Location: Animal Disease ResearchTitle: Association of TMEM8B and SPAG8 with mature weight in sheep
|CINAR, MEHMET - Erciyes University|
|HERNDON, MARIA - Washington State University|
|Taylor, Joshua - Bret|
Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2020
Publication Date: 12/15/2020
Citation: Cinar, M.U., Mousel, M.R., Herndon, M.K., Taylor, J.B., White, S.N. 2020. Association of TMEM8B and SPAG8 with mature weight in sheep. Animals. 10(12). Article 2391. https://doi.org/10.3390/ani10122391.
Interpretive Summary: Understanding how traditional livestock selection changes DNA allows for additional tools to manage and improve production and health of livestock. One region of sheep chromosome 2 has been shown to be under great change for an unknown reason. This study looked at a single change in each of two genes (TMEM8B and SPAG8) found in the region of selection and tested if individual ewe growth or lifetime production traits were associated with these DNA changes. Nearly 800 sheep of four different breeds were included in the study. Specifically, Polypay produce many lambs, Rambouillet produce very high-quality wool used to make clothing, Targhee are dual purpose sheep known for being adapted to extensive management systems, and Suffolk produce fast growing and meaty lambs. Weight of sheep at 3 and 4 years of age was influenced by changes in TMEM8B and SPAG8 where the DNA change fixed in Suffolk sheep had heavier weights. No other growth or lifetime measurement associated with the two evaluated DNA changes in these two genes. This is the first time TMEM8B has been associated with body weight in any species. These results should be verified in other breeds of sheep and additional scrutiny of the region of high selection on chromosome 2 needs to be conducted. Once confirmed, these DNA changes could be used to improve sheep production through selective breeding.
Technical Abstract: Signature of selection studies have identified many genomic regions with known functional importance, and some without verified functional roles. Multiple studies have identified TMEM8B rs426272889 as having been under extreme recent selection pressure in domesticated sheep, but no study had provided sheep phenotypic data clarifying a reason for extreme selection. We tested rs426272889 for production trait association in 779 U.S. Rambouillet, Targhee, Polypay, and Suffolk sheep. TMEM8B rs426272889 was associated with mature weight at 3 and 4 years (P<0.05). This suggested selection for sheep growth and body size might explain the extreme historical selection pressure in this genomic region. We also tested SPAG8 rs160159557 encoding a G493C substitution. While this variant was associated with mature weights at ages 3 and 4, it was not as strongly associated as TMEM8B rs426272889. Transmembrane protein 8B has little functional information except as an inhibitor of cancer cell proliferation. To our knowledge, this is the first study linking TMEM8B to growth and body size under normal conditions. Additional work is necessary to identify the underlying functional variant(s). Once identified, such variants could be used to improve sheep production through selective breeding.