Differences between Brahman and Holstein cows in heat-shock induced alterations of protein synthesis and secretion by oviducts and uterine endometrium.

Abstract

Our objectives were to test differences in protein synthesis and secretion by cultured oviducts and endometrium from Brahman and Holstein cows and the response of those tissues to in vitro heat shock. Explants of oviductal tissue obtained at estrus from Holstein (n = 5) and Brahman (n = 6) cows were cultured at a homeothermic (39 degrees C) or heat shock (43 degrees C) temperature. At 6 h, cultures were pulse-chase labeled (2 h, L[4,5-3H]leucine; 2 h, L-leucine). Endometrial explants were cultured similarly except that pulse labeling was performed for the first 0 to 15, 0 to 30, 30 to 60 and 60 to 90 min following onset of heat shock. A temperature of 43 degrees C increased secretion of nondialyzable 3H-labeled macromolecules by both oviducts of Brahmans but depressed secretion by the oviduct ipsilateral to the side of ovulation of Holsteins. For both breeds, 43 degrees C decreased incorporation of [3H]leucine into trichloroacetic acid (TCA)-precipitable radioactivity in oviducts from the ipsilateral side. Secretion of 3H-labeled macromolecules by pulse-labeled endometrial explants increased at 43 degrees C. Heat shock caused an immediate increase in TCA-precipitable radioactivity in tissue during pulse labeling for Holstein tissues. Incorporation was decreased at 43 degrees C in tissue from Brahmans in the first 30 min and increased thereafter. Incorporation of [3H]thymidine by endometrial explants from Brahmans was increased at 43 degrees C, whereas it was suppressed at 43 degrees C in explants from Holstein cows. Heat shock proteins of 72,000 and 90,000 molecular weight were present in endometrial tissues. A major secretory product of endometrium had a molecular weight of 57,500 for Brahmans and a lower molecular weight (55,600) for Holsteins.