@conference {41469,
	title = {Expression of the tight junction protein zonula occludens-1 during mammary engorgement},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {64},
	year = {2004},
	month = {Jan},
	pages = {43-47},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {An increase in tight junction (TJ) permeability occurs during extended milking intervals and is associated with reduced milk secretion. This paper examines temporal changes in the expression of a major TJ protein, zonula occludens-1 (ZO-1), during mammary engorgement. Alveolar mammary tissue was collected from 52 mid-lactation dairy heifers at 0, 6, 12, 18, 24, 36 and 72 h, and at 8 d following abrupt cessation of milking (n >= 6 cows per time point). ZO-1 protein expression significantly decreased during mammary engorgement (P<0.05). Similarly, ZO-1 mRNA expression had halved by 36 h to 8 d post-milking (P<0.05). In a second trial, alveolar tissue was collected from the udder halves of late-lactation dairy cows (n = 4) that were milked unilaterally, either once-daily or twice-daily for 4 days. A 1.7-fold increase in ZO-1 mRNA expression was detected after once-daily milking, compared with twice-daily milking (P<0.05). The down-regulation of ZO-1 during mammary engorgement is consistent with increased TJ permeability. However, the up-regulation of ZO-1 mRNA expression during short-term once-daily milking suggests that TJ function is repaired as the mammary gland adjusts to the extended milking interval. In conclusion, we have identified changes in ZO-1 critical to TJ function in bovine mammary glands. },
	issn = {1176-5283},
	author = {Cooper CV and Stelwagen K and Singh K and Farr VC and Prosser CG and Davis SR}
}
