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Title: A deleterious effect associated with UNH159 is attenuated in twin embryos of an inbred line of tilapia (Oreochromis aureus)

item SHIRAK, ANDREY - Israel Agricultural Research Organization (ARO)
item Palti, Yniv
item BERN, ORNA - Bar-Ilan University
item KOCHER, THOMAS - University Of Maryland
item HULATA, GIDEON - Israel Agricultural Research Organization (ARO)
item RON, MICHA - Israel Agricultural Research Organization (ARO)
item AVTALION, RAMY - Bar-Ilan University

Submitted to: Journal of Fish Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2012
Publication Date: 4/1/2013
Citation: Shirak, A., Palti, Y., Bern, O., Kocher, T.D., Hulata, G., Ron, M., Avtalion, R. 2013. A deleterious effect associated with UNH159 is attenuated in twin embryos of an inbred line of tilapia (Oreochromis aureus). Journal of Fish Biology. 82:42-53.

Interpretive Summary: Identification of the genes that affect sex determination in tilapia is important for growers as a means to avoid early life cycle reproduction in aquaculture systems. Previous work on inbred lines identified genetic markers that are linked to sex determination and are associated with deleterious effects. We extended this work to add a set of genes to the genome map of tilapia to create a comparative map with model species and support identification of candidate genes which may be involved in sex determination or differentiation. Identification of these genes will permit the use of markers to enhance production efficiency in this species.

Technical Abstract: Offspring of a highly inbred gynogenetic line of Oreochromis aureus displayed 12-fold increase in twinning rate compared to the outbred population. Asymmetric conjoined twins which consist of a normal embryo attached to a malformed-atrophic twin were frequently encountered in both gynogenetic (90.7%) and outbred (38.2%) spawns. The monozygotic origin of these twins was determined using five microsatellite markers. Progeny of heterozygous parents for the microsatellite UNH159 were separated into subsets of twins and normal full sibs. Consistent with previous reports, the normal embryo subset exhibited elimination of both types of homozygotes for the UNH159 genetic marker at 2-8 days after fertilization. Unexpectedly, this elimination was less frequent in twins. We mapped the UNH159 marker as well as RBMX, SOX3 and ATRX genes to linkage group 2. These gene orthologs are all located on the mammalian X chromosome and ATRX is necessary for the X-chromosome inactivation.