| Autor: |
Davis, George H., Galloway, Susan M., O'Connell, Anne R., Farquhar, Phillip A., McNatty, Kenneth P., Juengel, Jennifer L. |
| Zdroj: |
Biology of Reproduction; May 2008, Vol. 78 Issue: 1, Number 1 Supplement 1 p110-110, 1p |
| Abstrakt: |
Mutations responsible for increased ovulation rate in Booroola (FecB) and Inverdale (FecXI) sheep have been identified in two genes belonging to the TGFβ superfamily. Data suggest that the very similar maternally imprinted Woodlands (FecX2W) and Metherell (FecX2M) genes are on the X-chromosome and there is some anecdotal evidence that these may be the same mutation. This knowledge has provided the opportunity to study the interactions between major genes by breeding ewes carrying copies of three major genes for prolificacy and measuring ovulation rates. During 2000 - 2003, progeny tested sires carrying FecX2W or FecX2M were joined with a small flock of ewes that each carried a copy of the FecB and FecXI genes. DNA marker tests for FecB and FecXI identified four daughters that carried a copy of each gene. In addition, because FecX2W and FecX2M are carried on the X-chromosome all daughters inherit a copy of these genes from their sire. On this basis four ewes carrying each of three mutations were identified. In 2005 and 2006 these four ewes had ovulation rates measured six times at 17-22 day intervals during the autumn breeding season. The mean ovulation rates were 11.0 (SE = 0.54; range = 7-13), 7.6 (SE = 0.33; range = 6-10), 7.8 (SE = 0.61; range = 4-11) and 7.7 (SE = 0.68; range = 3-10) for the four ewes respectively. Ovulation rates of 11 contemporary wild-type ewes from the same genetic background averaged 2.1 (SE = 0.13; range = 1-3). Single copies of FecB, FecXI and FecX2W have been shown to increase ovulation rate by 1.5, 1.0 and 0.4 respectively, but the very high ovulation rates among the ewes carrying all three genes suggests a synergistic interaction. It has been previously shown that FecB and FecXI interact to increase ovulation rate by 35% more than predicted from an additive model. Data from the present study suggest that FecX2W and FecX2M also interact synergistically with the TGFβ pathway as animals carrying one copy of each of three genes have ovulation rates increased by 100 200% more than predicted from an additive model. Hence, animals carrying three mutations affecting ovulation rate provide a unique resource for determining how the products of these genes interact to induce this greatly enhanced ovulation rate, and a program is underway to establish a research flock of these sheep. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
