Activity of polyamine synthesising enzymes in wool follicles.

Abstract

Proc. Aust. Soc. Anim. Prod. Vol. 18 ACTIVITY OF POLYAMINE-SYNTHES ISING ENZYMES IN WOOL FOLLICLES T.M. JARVIS*, P.I. HYND* and A.M. SNOSWELL* Inhibition of ornithine decarboxylase (ODc3 8 the rate-limiting enzyme in polyamine synthesis, alters the ratio of length growth rate (L) to diameter (D) of wool fibres (Reis 1989; Reis and Hynd 1989), suggesting a vital role for the polyamines in follicle function. This paper examines the effects of nutrition on the activity of two of the main enzymes involved in polyamine synthesis, ornithine decarboxylase (ODC) and S-adenosyl methionine decarboxylase (SAMDC), in wool follicle preparations. Three adult strongwool Merinos (Bungaree strain), were offered a low plane of nutrition (400 g/day wheaten straw) for 3 weeks, followed by a high plane of nutrition (2000 g/da of lucerne pellets) for a further 6 weeks. Wool fibre L Midside was estimated using 35 S labelling in the final-week of each period. patches were clipped at 3-week intervals. Strips of skin (200mm x 2mm) were removed from the midside of the sheep and immediately placed in cold (4C) buffer. The follicle bulb region of the dermis was excised, homogenised (by ultraturrax and ultrasonication) in buffer (1:2 tissue:buffer) and centrifuged for 5 minutes. Enzyme activities in the supernatant were estimated from the rate of 14co liberation (trapped in phenalethalamine) from 14C0,-labelled ornithine (for2 ODC) or 14C-S-adenosyl methionine (for SAMDC). Table 1 Effects of nutritson (Low or High plane) on fibre L (urn/d), patch wool growth (mg/cm /d) and enzyme activity (pmol/h/mg protein). Nutrition significantly altered fibre L (P~O.022) and patch wool output (P<O.O05), had no effect on ODC activity (P=O.76), and significantly altered SAMDC activity (P<O.O20). We tentatively conclude that the supply of decarboxylated SAM, not putrescine, normally limits wool growth. REIS, P. J. (1989). In 'The Biology of Wool and Hair', p. 185, editors G-E. Rogers, P-J. Reis, K-A. Ward and RX. Marshall. (Chapman and Hall Ltd.: London). REIS, P. J. and HYND, P. I. (1989). Asian-Australasian J. Anim. Sci. 2:204. * Dept Animal Sciences, Waite Agric. Res. Inst., Glen Osmond, S.A- 5064. 498