Mh. Cake et al., KINETIC-BEHAVIOR OF MUSCLE CARNITINE PALMITOYLTRANSFERASE-I IN THE LAMPREY GEOTRIA-AUSTRALIS, BEFORE AND AFTER THE MARINE TROPHIC PHASE, The Journal of experimental zoology, 281(1), 1998, pp. 6-11
This study was aimed at determining whether the marked changes that oc
cur in the diet during the life cycle of the lamprey Geotria australis
, and thus also in the fatty acid composition of the triacylglycerol s
tores, are accompanied by alterations in the v(max) and apparent K-0.5
of skeletal muscle carnitine palmitoyltransferase I (CPT I) towards t
he CoA derivatives of the fatty acids 16:0, 16:1n-7, 18:1n-9, 18:2n-6,
and 22:6n-3. The activity of CPT I towards the last four of these acy
l CoAs increased progressively from the microphagous larvae to young a
dults, prior to the onset of their marine trophic phase, to fully grow
n adults, which had ceased feeding on fish and embarked on their spawn
ing run. For example, the nu(max) of CPT I towards 18:1n-9 rose from 4
.4, to 7.6 to 11.5 nmol.min(-1).mg mitochondrial protein(-1) over the
course of the three life-cycle stages. The values for the nu(max) of l
amprey muscle CPT I towards the various CoA esters were not directly c
orrelated with the percentage contributions of the corresponding fatty
acids to the triacylglycerol stores. Despite very pronounced differen
ces in the biochemistry, physiology, and physical activity of each lif
e-cycle stage, as well as in the fatty acid composition of the triacyl
glycerols, before and after the adult trophic phase, the nu(max) for C
PT I was always greatest for 16:1n-7 and 18:1n-9. Because the reactivi
ty of CPT I towards the latter two monoenoic fatty acids is also high
in teleost fishes and in rat, such a characteristic may have been cons
erved throughout vertebrate evolution. (C) 1998 Wiley-Liss, Inc.