PROCEEDINGS OF THE BIOCHEMICAL SOCIETY 21 p are apparently correlated with changes in dihydroxy- of sucrose-fed animals were always higher than those acetone phosphate concentration. In non-diabetic of controls. ATP citrate lyase (EC 22.214.171.124) and 'malic' rats they are both decreased in starvation and in- enzyme (EC 126.96.36.199) increased in activity after creased 48 h after re-feeding with glucose, glycerol or weaning to a maximum at 35-40 days of age and then sucrose. Further, in diabetes the activity of liver-type fell to the end of the experiment, and feeding with pyruvate kinase and dihydroxyacetone phosphate sucrose caused elevated activities at all ages studied. concentration are decreased, and in this state both Extramitochondrial aconitate hydratase (EC 188.8.131.52) are raised by treatment with insulin and by re-feeding and NADP-dependent isocitrate dehydrogenase (EC with sucrose or glycerol but not with glucose. How- 184.108.40.206) activities fell after weaning until 25-30 days ever, no causal relationship has been established. of age and then rose throughout the rest of the The authors are indebted to the Science Research experimental period. From 30 days of age the activi- Council for a grant to J. M. G. ties of both these enzymes were lowered by feeding with sucrose. Glucose 6-phosphate dehydrogenase Bailey, E., Taylor, C. B. & Bartley, W. (1968) Nature (EC 220.127.116.11) activity rose rapidly after weaning to (London) 217,471 40 days of age and then remained constant for the Sillero, A., Sillero, M. A. G. & Sols, A. (1969) Eur. J. remainder of the experimental period. Feeding with Biochem. 10, 351 sucrose increased this enzyme activity at all ages Weber, G., Singhal, R. L., Stamm, N. B., Lea, M. A. & studied. Fisher, E. A. (1966a) Advan. Enzyme Regul. 4, 59 Weber, G., Lea, M. A., Fisher, E. A. & Stamm, N. B. We thank the Medical Research Council for a grant to (1966b) Enzymol. Biol. C/in. 7, 11 J. R. W. The Effect on the Activities of some Hepatic Bailey, E., Taylor, C. B. & Bartley, W. (1968) Nature (London) 217, 471-472 Enzymes of Weaning Rats on to a Diet High in Lockwood, E. A., Bailey, E. & Taylor, C. B. (1970) Sucrose Content Biochem. J. 118,155-162 Taylor, C. B., Bailey, E. & Bartley, W. (1967) Biochem. J. By JENNIFER R. WEBB and E. BAILEY (Department of 105, 717-722 Biochemistry, University of Sheffield, Sheffield S10 2TN, U.K.) Changes in the Activities of some Kidney There is a marked increase in hepatic lipogenesis Enzymes during Development of the Rat and the activities of enzymes associated with lipo- genesis on weaning rats from the high-fat-content By CHRIsTINE A. HAUSER, ELIZABErH A. LOCKWOOD milk diet of suckling to the high-carbohydrate and E. BAILEY (Department of Biochemistry, Univer- (starch)-content laboratory diet (Taylor et al., 1967; sity of Sheffield, Sheffield S10 2TN, U.K.) Lockwood et al., 1970), Hepatic lipogenesis is also considerably higher in rats fed on sucrose rather than Although changes in the activities of many hepatic on starch-containing diets (Bailey et al., 1968). To enzymes during development of the rat are well docu- investigate further the involvement of diet in the post- mented, little is known about the developmental weaning increase in lipogenesis we have studied the changes that occur in the activity of rat kidney en- effect on the activity of some enzymes involved in zymes (for review see Greengard, 1971). We have carbohydrate conversion into fatty acids of weaning measured the postnatal changes that occur in the female rats on to a diet high in sucrose content. activities of the following kidney enzymes: hexo- Fructokinase (EC 18.104.22.168) activity increased after kinase (EC 22.214.171.124), pyruvate kinase (EC 126.96.36.199), weaning (at 21 days of age) to a maximum at 40-45 'malic' enzyme (EC 188.8.131.52), glucose 6-phosphate days and then fell to pre-weaning values by the end dehydrogenase (EC 184.108.40.206), extramitochondrial of the experiment (70 days of age), and feeding with NADP-dependent isocitrate dehydrogenase (EC sucrose had little effect on the enzyme activity. 220.127.116.11), extramitochondrial aconitate hydratase Phosphofructokinase (EC 18.104.22.168) and fructose 1,6- (EC 22.214.171.124), ATP citrate lyase (EC 126.96.36.199) and diphosphatase (EC 188.8.131.52) activities varied little fructose 1,6-diphosphatase (EC 184.108.40.206). We have during the period studied and dietary sucrose had also measured developmental changes in the in- little effect on the activity of either enzyme. Aldolase corporation of [U-14C]acetate into lipid by kidney (EC 220.127.116.11) activity was constant between 21 days homogenates. The experiments were carried out with and 40 days of age, rose to a maximum at 50 days both male and female rats weaned at 21 days of age, and then fell to 70 days of age. Feeding with sucrose and unless otherwise stated similar results were caused slightly elevated aldolase activities at all ages obtained with both sexes. studied. Pyruvate kinase (EC 18.104.22.168) activity rose Hexokinase activity increases after birth to a maxi- steadily during the experiment to a maximum at mum at 30 days of age, thereafter falling to reach about 50-60 days of age, and activities in the livers adult values by 50 days of age. These results extend 22 p PROCEEDINGS OF THE BIOCHEMICAL SOCIETY the findings of Sydow (1969). The activity of pyruvate Male Wistar rats were force-fed on a protein-free kinase, the other glycolytic enzyme studied, changed purified diet for 5-7 days. In agreement with our very little during the period investigated. Glucose previous work, the activity of microsomal UDP- 6-phosphate dehydrogenase activity fell slightly after glucuronyltransferase in livers from these animals birth to a minimum at 20 days of age and then rose was substantially higher than in those from control gradually to reach adult values at 50 days of age. animals fed on the same diet supplemented with 18% Isocitrate dehydrogenase and 'malic' enzyme ex- casein (protein-deficient, 148.7±13.4nmol of glucur- hibited similar developmental patterns, the activities onide formed/h per mg of microsomal protein; of both enzymes rising steadily throughout postnatal controls, 63.2±6.8). development. The activity of kidney 'malic' enzyme Although the weights of microsomal protein and was 50 % higher in female rats than in male rats. phospholipid per g of liver were both 30 % lower in Extramitochondrial aconitate hydratase activity protein-deficient animals than in control animals, increased after birth, reaching adult values by 20 days there was no significant difference in the ratio of of age. ATP citrate lyase activity, which was very low phospholipid to protein between the groups (protein- throughout development, fell after birth to a mini- deficient, 1.07±0.03g/g; controls, 1.00±0.01 g/g). mum at 20 days of age and then rose steadily to adult The microsomal phospholipid compositions were values. [U-14C]Acetate incorporation into lipid rose similar in the two groups, but there were significant after birth to a maximum at 20 days of age and then differences in the content of phosphatidylinositol fell to a minimum at 50 days of age, thereafter rising (protein-deficient, 6.1±0.5% of total phospholipid; to adult values. Fructose 1,6-diphosphatase activity controls 8.7±0.3%.) and sphingomyelin (protein- rose after birth, reaching adult values at about 30 days deficient, 7.0 ±0.6 %; controls, 4.2 ±0.3 Y.). Moreover, of age, thus exhibiting a similar developmental pattern lysophosphatidylcholine (7.4±0.5%) and lysophos- to that of glucose 6-phosphatase and gluconeo- phatidylethanolamine (3.1 ±0.9%) were found with genesis reported by Zorzoli et al. (1969). protein-deficient rats whereas no lysophosphatides were detected with control animals. We thank the Medical Research Council for grants to Hanninen & Puukka (1971) report that addition of C. A. H. and E. A. L. lysophosphatides to rat liver microsomal fractions or Greengard, 0. (1971) Essays Biochem. 7, 159-205 their treatment with phospholipase A increases Sydow, G. (1969) Hoppe-Seyler's Z. Physiol. Chem. 350, UDP-glucuronyltransferase activity. Treatment of 263-268 our control microsomal preparations with phospho- Zorzoli, A., Turkenkopf, I. J. & Mueller, V. L. (1969) lipase A showed that a degree of phospholipid hydro- Biochem. J. 111, 181-185 lysis similar to that observed in preparations from protein-deficient rats increased enzyme activity 2-3- fold. Effects of Protein Deficiency on Uridine We therefore suggest that the elevated enzyme Diphosphate Glucuronyltransferase Activity and activity in microsomal fractions from protein-defici- Phospholipid Composition of Rat Liver ent rats is probably due to the presence of lysophos- Microsomal Fraction phatides. The involvement of other factors such as the alterations of phosphatidylinositol and sphingo- By ALLAN B. GRAHAM, GEOFFREY C. WOOD and myelin contents cannot, however, be excluded. BARRY G. WOODCOCK (Drug Metabolism Research Unit, Department of Pharmaceutical Chemistry, We gratefully acknowledge support for this work from University ofStrathclyde, Glasgow G1 1 XW, U.K.) the Medical Research Council and the Science Research Council. Protein deficiency markedly increases the activity of rat liver microsomal UDP-glucuronyltransferase Attwood, D., Graham, A. B. & Wood, G. C. (1971) with o-aminophenol or p-nitrophenol as acceptor Biochem. J. 123, 875-882 (Wood & Woodcock, 1970; Woodcock & Wood, Graham, A. B. & Wood, G. C. (1969) Biochem. Biophys. Res. Commun. 37, 567-575 1971). Since the enzyme's activity is affected by treat- Hanninen, 0. & Puukka, R. (1971) Chem.-Biol. Inter- ment of microsomal preparations with agents per- act. 3, 282-284 turbing the phospholipids of the microsomal mem- Wood, G. C. & Woodcock, B. G. (1970) J.Pharm.Pharma- brane (Graham & Wood, 1969; Attwood et al., col. 22, 60S-63S 1971; Hanninen & Puukka, 1971), it was suggested Woodcock, B. G. & Wood, G. C. (1971) Biochem. (Woodcock & Wood, 1971) that protein deficiency Pharmacol. 20, 2703-2713 might affect enzyme activity by altering the structure of the microsomal membrane. We have therefore determined the phospholipid composition of liver microsomal preparations from normal and protein- deficient rats.