Highly prolific Booroola sheep have a mutation in the intracellular kinasedomain of bone morphogenetic protein IB receptor (ALK-6) that is expressedin both oocytes and granulosa cells
T. Wilson et al., Highly prolific Booroola sheep have a mutation in the intracellular kinasedomain of bone morphogenetic protein IB receptor (ALK-6) that is expressedin both oocytes and granulosa cells, BIOL REPROD, 64(4), 2001, pp. 1225-1235
The Booroola fecundity gene (FecB) increases ovulation rate and litter size
in sheep and is inherited as a single autosomal locus. The effect of FecB
is additive for ovulation rate (increasing by about 1.6 corpora lutea per c
ycle for each copy) and has been mapped to sheep chromosome 6q23-31, which
is syntenic to human chromosome 4q21-25. Bone morphogenetic protein IB (BMP
-IB) receptor (also known as ALK-6), which binds members of the transformin
g growth factor-beta (TGF-beta) superfamily, is located in the region conta
ining the FecB locus. Booroola sheep have a mutation (Q249R) in the highly
conserved intracellular kinase signaling domain of the BMP-IB receptor. The
mutation segregated with the FecB phenotype in the Booroola backcross and
half-sib flocks of sheep with no recombinants. The mutation was not found i
n individuals from a number of sheep breeds not derived from the Booroola s
train. BMPR-IB was expressed in the ovary and in situ hybridization reveale
d its specific location to the oocyte and the granulosa cell. Expression of
mRNA encoding the BMP type II receptor was widespread throughout the ovary
. The mutation in BMPR-IB found in Booroola sheep is the second reported de
fect in a gene from the TGF-beta pathway affecting fertility in sheep follo
wing the recent discovery of mutations in the growth factor, GDF96/BMP15.