De novo synthesis and release of polypeptides from cyclic and early pregnant porcine oviductal tissue in explant culture

Abstract

The objective of the present study was to identify and characterize in a limited manner the major de novo oviductal secretory proteins (OSP) synthesized and released by the porcine oviduct. Oviductal tissue was collected on various days of the estrous cycle (EC) and early pregnancy (EP) and cultured in a modified minimal essential medium supplemented with 100 muCi L-[3H]-leucine. Oviductal secretory activity, as measured by the rate of incorporation of 3H-leucine (dpm/mg wet tissue weight) into nondialyzable macromolecules, was greatest (P less than .01) between days 0 and 2 and reached its lowest levels on days 10 to 15. There was no difference between left and right side or pregnancy status. This increased rate of incorporation at proestrus and estrus is temporally associated with elevated levels of estrogen. Incorporation rate for ampulla was greater than for the isthmus. Analysis of oviductal culture medium by one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis and fluorography revealed three protein bands of relative molecular weight (Mr) 335,000, 115,000, and 85,000, which were associated with proestrus, estrus, and metestrus and were not detectable on other days. All three proteins also incorporated 3H-glucosamine. The 115,000 Mr band was the major 3H-glucosamine-labeled protein. Two protein bands (Mr 60,000 and 20,000) were expressed with increasing progesterone during diestrus. Other de novo synthesized protein bands appear to be present throughout the EC and EP with little modulation by estrogen or progesterone. Thus, this study demonstrates that for the porcine oviduct, the increase in the incorporation rate of 3H-leucine into OSP by both whole oviduct and ampulla and de novo synthesis and secretion of three glycoproteins, Mr 335,000, 115,000, and 85,000, were associated with proestrus and estrus when events such as fertilization and early cleavage stages of embryo development occurred.

Determination of glycosidase activity in porcine oviductal fluid at the different phases of the estrous cycle

“…In sows, Iritani et al (1974) described no changes in protein concentration during the estrous cycle. A higher secretion rate of proteins has been described at proestrus and estrus when events such as fertilization and early cleavage stages of embryos occur (Buhi et al 1989). This would be more in agreement with our results showing a higher total amount of protein at estrus.…”

Regulation of IGF-I and porcine oviductal secretory protein (pOSP) secretion into the pig oviduct in the peri-ovulatory period, and effects of previous nutrition

“…The strong correlations between these different characteristics support the concept that the oviduct environment is indeed associated with changes in steroids in the peri-ovulatory period. In particular, the inverse relationship between protein concentrations and the concentrations of P 4 is consistent with the findings of Buhi et al [8] who showed that porcine oviductal tissue during estrus has the highest levels of de novo protein synthesis and secretion. The temporal changes in pOSP mRNA expression and the secreted pOSP proteins in relation to the time of ovulation are consistent with evidence that pOSP expression is E 2 -dependent [11].…”

“…Furthermore, de novo protein synthesis and secretion by explanted porcine oviducts was the highest for tissue recovered at estrus and was associated with elevated E 2 concentrations [8]. Finally, in Experiment 1, the highest total protein concentration was seen in oviduct flushings in the pre-ovulatory period and was associated with a higher E:P ratio.…”

Secreted Proteins of the Oviduct

“…Oviductal biosynthetic activity is greater under estrogen than progesterone domination. Significantly greater activity has been demonstrated in the oviduct of the pig [Buhi et al, 1989], sheep [Buhi et al, 1991] and cow [Geisert et al, 1987;Malayer et al, 1988] at estrus and at mid cycle in the human [Buhi, unpublished] than on other days of the cycle. Furthermore, this increase in biosynthetic activity is reflected in the activity of certain functional segments during the estrous cycle and early pregnancy ( fig.…”

“…1). In the pig [Buhi et al, 1989[Buhi et al, , 1997a, significantly increased synthesis and secretion was shown by the infundibulum and ampulla at estrus compared to other days of the cycle or early pregnancy. No change in activity was demonstrated for the isthmus regardless of day or status.…”