@conference {40305,
	title = {Effect of high and sustained zinc supplements on trace element metabolism in sheep},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {51},
	year = {1991},
	month = {Jan},
	pages = {173-178},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Alpha-lactalbumin (alpha-lac) is a component of the enzyme  complex lactose synthetase which plays a key role in the regulation of  lactose synthesis and milk water secretion. Ribozyme mediated  manipulation of alpha-lac expression should enable more precise  elucidation of its physiological significance and may lead to the  development of transgenic animals.   Five ribozymes and controls targeting different regions of the alpha-sac  gene have been synthesised and cloned. In vitro ribozyme  analysis involved the incubation of in vitro transcribed alpha-  lac and ribozyme RNA. The rate of ribozyme cleavage in vitro was  influenced by temperature, MgC1 2 concentration, length of antisense  flanking sequences and region of the alpha-lac gene targeted.   In vivo ribozyme analysis was carried out in the T7/vaccinia  expression system using C127I mouse mammary cells. This system utilises  the powerful bacteriophage T7 RNA polymerase which is expressed when  cells are infected with a recombinant vaccina virus. Gene constructs,  cloned into vaccina plasmids downstream from a T7 promoter are  transfected into the cells and are transcribed and translated at very  high levels. Using this system we have identified that ribozymes that  targeted exposed stem loops and the 3{\textquoteright} end of the gene down regulated  the level of alpha-lac RNA to 10-20\% of the controls. Similar  reductions in expression of alpha-lac protein were observed for these  key ribozymes, but in addition a full length antisense was equally as  effective. The expression of these ribozymes in transgenic mice will  enable evaluation of their effectiveness to influence lactose synthesis  and milk water secretion.  },
	issn = {1176-5283},
	author = {Lee J and Grace ND and Martell S}
}
