Gene Expression of Aquaporins (AQPs) in Cumulus Oocytes Complex and Embryo of Cattle

SIMPLE SUMMARY: Aquaporins are membrane channels that allow for the movement of water and solutes in cells. They have been reported to play crucial roles in mammalian early development and cryopreservation processes. However, there are few studies focused on the characterization of aquaporins in cumulus oocyte and embryo complexes of cattle. Moreover, no studies have been carried out on Brahman, Holstein, Gir and Romosinuano, important bovine breeds in milk and meat production. Therefore, the objective of this study was to evaluate their presence, transcript level and possible functions in the cumulus oocyte complex of the Brahman, Holstein, Gir and Romosinuano breeds and in embryos from five bovine crosses. Aquaporins 1–12 were found in both cumulus oocyte complexes and embryos, and we found possible parental effects on the expression of aquaporins 6 and 12b in cumulus oocyte complexes and aquaporins 4, 8 and 9 in embryos. This allows one to evidence possible functions in the early development of the Brahman, Holstein, Gir and Romosinuano bovine breeds. ABSTRACT: Aquaporins (AQPs) are proteins with various functions related to proper cell function and early development in mammals. The aim of this study was to evaluate the presence of AQPs and determine their mRNA levels in the cumulus oocyte complex (COC) of four bovine breeds and in blastocysts of five bovine crosses. Grade I, II and III COCs were collected by ovum pick up from non-lactating heifers of the Brahaman, Holstein, Gir and Romosinuano breeds. Embryos were produced in vitro up to the blastocyst stage of the bovine ♀Gir × ♂Holstein, ♀Holstein × ♂Gir, ♀Brahman × ♂Holstein, ♀Holstein × ♂Brahman, and ♀Romosinuano × ♂Holstein crosses. mRNA expression of AQP1-AQP12b was estimated in COC and embryos by real-time-PCR. The presence of the twelve AQPs in the COCs and bovine embryos was established. Additionally, significant differences were determined in the expression of AQP6 and AQP12b in COCs, as well as in transcripts levels of AQP4, AQP8 and AQP9 from bovine embryos. Gene expression of AQPs in COCs and bovine embryos is consistent with the previously described biological functions. This is the first report of AQPs in COC of Gir, Brahman, Holstein and Romosinuano and embryos of five crossbreeds between Bos indicus and B. taurus.