Delayed parturition in cloned calves associated with persistently elevated placentomal TGF-β 1 expression

Abstract

The objective of this study was to investigate hormonal and TGF-β 1 characterizations of delayed parturition in the SCNT recipients (Korean native beef cattle: Hanwoo). The SCNT blastocysts produced by Hanwoo fetal fibroblast cells were transferred into the synchronized Hanwoo recipients. The artificially inseminated Hanwoo recipients (AI-R) were used as control. All AI-R were labored by natural delivery. The SCNT recipients (SCNT-R) with no signs of delivery were operated by Caesarean section. The blood and placentomes were collected during parturition. The weight of placentomes in SCNT-R ( n = 12, 301 ± 41.22 g) was significantly higher than that of AI-R ( n = 10, 204.8 ± 24.89 g) ( p < 0.05). There were significantly lower E2 ( p < 0.05) or higher P4 ( p < 0.01) and TGF-β 1 ( p < 0.01) levels in the SCNT-R compared to that of AI-R, respectively. The SCNT-R showed a higher placentomal TGF-β 1 protein level compared to that of AI-R ( p < 0.01). Interestingly, the TGF-β 1 protein level in SCNT-R with normal delivery was dramatically decreased as same as AI-R, but it was highly maintained in C-sec at days 250 of pregnancy in AI-R. These results suggest that delayed parturition in clone calving may be associated with persistence of elevated TGF-beta-1 expression in late pregnancy.