Identification of the DDAH2 Protein in Pig Reproductive Tract Mucus: A Putative Oestrus Detection Marker

Abstract

Precisely detecting oestrus is important for artificial insemination. The aims of this study were to identify oestrus-specific sow mucus proteins to determine the optimal time for artificial insemination. The proestrous- and oestrous-stage mucus proteins were purified and analysed with proteomic tools such as two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization-time-of-flight analyses. Among the differentially expressed proteins, the dimethylarginine dimethylaminohydrolase 2 (DDAH2) protein showed a 3.6-fold increase during the proestrous stage compared to that during the oestrous stage. A western immunoblot study revealed that two of three sow mucus samples clearly showed negative anti-DDAH2 antibody activity during the oestrous stage. This study demonstrated that the pig DDAH2 mucus protein exists during the proestrous stage, but not during the oestrous stage, suggesting that mucus DDAH2 could be useful as an oestrus detection marker.

Histomorphometry and uterine proteomics during the normal reproductive cycle in bitches

“…This finding is possibly related to the participation of these proteins in preparing the uterus for the reception of gametes during fertilization. However, in bovine (Faulkner et al, 2013) and swine (Lee et al, 2013) species, the secretory or diestrus phase, under the action of progesterone, is reported as the phase with the highest number of proteins, differently from the canine species.…”

“…Although molecular dynamics studies are known in equine (Swegen et al, 2017), bovine (Faulkner et al, 2013), and swine (Lee et al, 2013), few studies have addressed the phases of the canine estrous cycle. It is essential to understand the proteomic profile in the proliferative phases, in which the uterus is adapted to receive sperm and, during the secretory phase, to receive the embryo.…”

“…Thus, substances synthesized and secreted by endometrial cells are essential for pregnancy and embryo survival (Holst, 2019), however, molecular changes in the glands and endometrial epithelium alter the composition of uterine secretions (Gao et al, 2009). Molecular studies have identified uterine proteins in domestic females (Faulkner et al, 2013;Lee et al, 2013;Freitas et al, 2015;Swegen et al, 2017), constituting potential biotechnological applicability for the early diagnosis and treatment of reproductive disorders. However, studies of proteomic analysis in dogs are scarce, addressing pyometra (Kuleš et al, 2020), pregnancy (Valdés et al, 2019) or diestrus phases (Praderio et al, 2019), estrus (Fahiminiya et al, 2010), and proestrus (Reynaud et al, 2015), lacking studies that cover all phases of the estrous cycle.…”