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The Journal of Nutrition Vol. 128 No. 11 November 1998,
pp. 1878-1883
Department of Diabetes, INSERM U341, Hôtel-Dieu Hospital, 75004 Paris and * INSERM U465, Institut Biomedical des Cordeliers, 75270 Paris cedex 06, France
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ABSTRACT |
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Abstract
Introduction
Methods
Results
Discussion
References
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The of this study was to evaluate the chronic effects of a high (waxy corn) vs. a low (mung beans) glycemic index starch diet on the lipogenic enzymes, fatty acid synthase (FAS) and lipoprotein lipase (LPL). Normal and diabetic (streptozotocin-injected on d 2 of life) male Sprague-Dawley rats consumed a diet containing 575 g/kg carbohydrates either as waxy cornstarch (WCS) or as mung bean starch (MBS). After 3 wk, neither body weights nor relative epididymal fat pad weights differed. In diabetic rats, the WCS diet induced high basal plasma insulin levels. Plasma triglycerides were not significantly affected by diet in either normal or diabetic rats. Adipose tissue and liver LPL activities were not modified by the type of starch in the diet. In normal rats, FAS activity and gene expression in epididymal adipose tissue but not in liver were greater in rats consuming the WCS diet than in those consuming MBS. To evaluate the implication of insulin in this regulation, two genes regulated by insulin [GLUT4 and phosphoenolpyruvate carboxykinase (PEPCK)] were also studied. The high glycemic index WCS diet compared with the low glycemic index MBS diet resulted in lower hepatic PEPCK mRNA in both normal and diabetic rats. Normal, but not diabetic rats fed WCS had greater GLUT4 gene expression in adipocytes than did those fed MBS. We conclude that the total replacement of 575 g/kg low glycemic index starch by a high glycemic index starch for 3 wk caused the following in normal rats: 1) high FAS activity and mRNA in adipose tissue but not in liver and 2) high GLUT4 gene expression in adipose tissue. In both normal and diabetic rats this same diet resulted in lower hepatic PEPCK mRNA. Therefore, high glycemic index starch diet is implicated in stimulating FAS activity and lipogenesis and might have undesirable long-term metabolic effects.
KEY WORDS: glycemic index · fatty acid synthase · lipoprotein lipase · adipose tissue · rats
The determination of factors that limit the postprandial rise in blood glucose has been recognized as a major aim of diabetes therapy. In prospective studies, postprandial hyperglycemia and hyperinsulinemia were shown to increase the risk of developing atherosclerotic heart disease (Ducimetriere et al. 1980 The main reason for high postprandial glycemia is a high carbohydrate diet. Attention has recently been focused on determining the best type of dietary carbohydrate to avoid deleterious postprandial changes. Only a few studies (Bornet et al. 1989 Fatty acid synthesis is a major metabolic pathway for the provision of energy reserves and cellular structural components. This pathway is regulated by complex nutritional and hormonal controls (Goodridge et al. 1986 In addition to an effect on lipid biosynthesis, dietary high glycemic index starch may also increase circulating lipid levels through an effect on LPL, one of the major lipoprotein-catabolizing enzymes (Eckel 1989 We chose a rat model of noninsulin-dependent diabetes induced by neonatal streptozotocin administration to Sprague-Dawley rats on d 2 after birth, (STZ-n2). This model is characterized by persistent hyperglycemia over 2-4 d after STZ administration, after which plasma glucose levels return to normal. By 4 wk of age, rats develop chronic hyperglycemia and insulin resistance with plasma glucose concentrations between 11 and 14 mmol/L (Levy et al. 1984 Thus, in this study, we evaluated the effects of two starches with different glycemic indices [WCS and mung bean starch (MBS)] on the activity and gene expression of enzymes implicated in lipogenesis, i.e., FAS and LPL in both normal and diabetic rats. To evaluate the implication of insulin peaks (after the high glycemic index starch diet), two genes regulated by insulin were also studied (GLUT4 and PEPCK).
Rats and diets.
Normal (n = 24) and diabetic (n = 24) male Sprague-Dawley rats (Centre d'Elevage Robert Janvier, Le Genest St-Isle, France) were used. Approval to use laboratory animals was given by the French Ministry of Agriculture, and the protocol complied with NIH guidelines (NRC 1985). Diabetes was induced by injecting rats with STZ (Zanosar R, Upjohn, La Défence, France) on d 2 of life (100 mg/kg body weight in 5 mmol/L citrate buffer, pH 4.5), according to the method described by Bonner-Weir et al. (1981)
Intraperitoneal glucose tolerance test.
Two tests were performed, before the start and 3 d before the end of the experimental period. On the morning of the experiment, food was removed at 0800 h. At 1400 h, rats were anesthetized with pentobarbital (0.5 mL/kg body weight). Blood samples were taken from the tip of the tail (time 0). A glucose challenge was given intraperitoneally (2 g glucose /kg body weight); other blood samples were taken after 15 and 50 min.
Measurement of FAS activity.
Epididymal adipose tissue and the liver were homogenized in ice-cold buffer containing 0.25 mol/L sucrose, 1 mmol/L dithiothreitol, 1 mmol/L EDTA, 0.1 mmol/L phenylmethylsulfonylfluoride, pH 7.4, and cytosolic fractions were obtained by centrifugation (1 h, 105000 × g at 4°C). Infranatants (below the fat cake) were immediately used for spectrophotometric assay of FAS (EC 2.3.1.85) by measuring malonyl-CoA-dependent oxidation of NADPH at 37°C, according to Halestrap and Denton (1973) Measurement of LPL activity.
Epididymal adipose tissue and skeletal muscle were homogenized (100 mg/mL) at 4°C in an extraction buffer containing 0.2 mol/L Tris-HCl, pH 8.3, 0.25 mol/L sucrose, 0.008% Nonidet (v/v), 2g/L Na-deoxycholate and 4 × 103 U/L heparin (Iverius and Brunzell 1985 RNA analysis.
Total RNA was extracted from frozen epididymal adipose tissue and liver samples as described by Chomczynski and Sacchi (1987) Quantification of FAS mRNA by semiquantitative RT-PCR.
Rat FAS mRNA was semiquantified in total RNA preparations by reverse-transcription reaction followed by polymerase chain reaction (RT-PCR). Total RNA was treated for 15 min at 37°C with RNase-free DNase I (RQ1 DNase, Promega, Madison, WI) 0.1 U/µg of nucleic acid in 40 mmol/L Tris-HCl, pH 7.9, 10 mmol/L NaCl, 6 mmol/L MgCl2 and 10 mmol/L CaCl2 in the presence of 2 U/µL of placenta RNase inhibitor (RNasine, Promega). After phenol/chloroform extraction and ethanol precipitation, RNA was quantified by spectrophotometry. Sample concentrations were adjusted according to optical densities. To further demonstrate that equal quantities of total RNA were loaded, samples of the RNA were resolved by electrophoresis and stained with ethidium bromide to quantify the 28S and 18S rRNA bands. RNA (2µg) underwent a RT reaction with Moloney Murine Leukemia Virus (M-MLV) RT (400 U/µg, Gibco BRL, Life Technologies, Cergy Pontoise, France) in the presence of 10 µmol/L random hexanucleotides (Pharmacia, Biotech, Orsay, France), 400 µmol/L of each dNTP and 2 U/µL of placenta RNase inhibitor. Final volume was adjusted to 40 µL with buffer (50 mmol/L Tris-HCl, pH8.3, 3 mmol/L MgCl2, 75 mmol/L KCl, and 10 mmol/L dithiotreitol). After a 30 min-incubation at 37°C, M-MLVRT was heat-inactivated at 95°C. To avoid contamination with genomic DNA, a control without M-MLV RT was included for each RNA sample. cDNA was amplified in the presence of 1 U Taq DNA Polymerase (Promega), 0.125 µL of 25 mmol/L each dNTP, 2 µL of 10X PCR buffer (500 mmol/L KCl, 100 mmol/L Tris-HCl, pH 8.3, and 0.1 g/L gelatin), 0.25 µL of 25 mmol/L MgCl2, 0.25 µL of 25 µmol/L each sense and antisense oligonucleotides for FAS and 0.15 µL of 25 µmol/L for Quantification of PEPCK and GLUT4 mRNA by Northern blot.
For the liver and epididymal adipose tissue, equal amounts (20 µg) of total RNA were applied onto 1% agarose gel containing 0.66 mol/L formaldehyde, fractionated by electrophoresis and transferred by capillarity onto nylon membrane (Positive membrane, Appligene, Illkirch, France). For hybridization of PEPCK, the filters were prehybridized (6 h at 42°C) and then hybridized overnight at 42°C in the presence of formamide. The pPC116 cDNA probe used is a 1305-bp length of rat PEPCK mRNA inserted into SmaI-SpHI sites of pBR 322 provided by D. K. Granner (Ganner et al. 1986). The cDNA probe was labeled with [ Measurement of plasma glucose, insulin and lipid concentrations.
Plasma glucose was measured by the glucose oxidase technique with a Beckman Glucose analyzer (Fullerton, CA). Plasma insulin (Insulin RIA kits, CIS Bio International, Gif sur Yvette, France), triacylglycerols (Enzymatic triglyceride kit, BioMérieux, Marcy-l'Etoile, France), cholesterol (Labintest cholesterol kit, Labintest, Aix-en-Provence, France), phospholipids (Enzymatic phospholipid kits, BioMérieux) and free fatty acids (Enzymatic free fatty acids kits, Nefa C*, Unipath, Dardilly, France) were also measured.
Statistical analysis.
Overall comparisons among the four groups were made by using two-way ANOVA to test effects of diet, diabetes and their interaction. In the presence of an interaction, the difference between the dietary groups was tested separately in diabetic and normal rats by Student's t test for unpaired data. When the variances associated with each experimental mean were heterogeneous, a logarithmic transformation was performed. All analyses were carried out with Statview 512+ software program (Brainpower, Calabasas, CA). Results are given as means ± SEM. Differences were considered significant when P < 0.05.
Body weight, food intake and epididymal adipose tissue weights.
Neither body weights nor food intakes were affected by diabetes or diet (Table 2). There was no difference in relative (per 100 g of body weight) epididymal fat pad weights between rats fed MBS or WCS diets or between normal and diabetic rats.
Intraperitoneal glucose tolerance test.
Plasma glucose responses were significantly higher, whereas plasma insulin responses were lower in diabetic rats than in normal rats before (results not shown) and at the end of the experimental period (Fig. 1). These results are consistent with previous results from our laboratory (Kabir et al. 1998
Plasma glucose, insulin and lipid concentrations.
At the end of the experimental period, the diabetic rats were hyperglycemic (P < 0.05) compared with the nondiabetic rats. Plasma triacylglycerol, cholesterol, free fatty acid and phospholipid concentrations did not differ in normal and diabetic rats (data not shown). Plasma insulin concentration was higher in diabetic rats fed the WCS diet than in those fed the MBS diet (P < 0.05) (Table 2).
FAS and LPL activities.
In normal rats, FAS activity was greater in those consuming the WCS diet (137 ± 14 vs. 230 ± 39 mU/mg protein, P < 0.05, MBS vs. WCS) in epididymal adipose tissue. No difference was found in the liver (35 ± 4 vs. 56 ± 9 mU/mg protein). In diabetic rats, there was no difference in the FAS activity in either the adipose tissue (153 ± 22 vs. 122 ± 23 mU/mg protein, MBS vs. WCS) or the liver (67 ± 16 vs. 52 ± 9 mU/mg protein, MBS vs. WCS). LPL activity was not affected by diet in normal or diabetic rats in adipose tissue or liver.
FAS, PEPCK and GLUT4 gene expression.
For adipose tissue, the analysis of FAS expression by RT-PCR showed that the WCS diet led to an overexpression of the FAS gene only in normal rats (P < 0.005); in diabetic rats, FAS expression was lower than that in normal rats and no difference was detected between the two diet groups. In liver, the expression of FAS did not differ in normal or diabetic rats fed the MBS or WCS diet (Fig. 2).
In this study, a high (waxy cornstarch, WCS) diet compared with a low glycemic index starch diet (mung bean starch, MBS) raised FAS activity and mRNA levels in adipose tissue of normal rats. This is the first evidence for a regulation of adipose tissue FAS gene by a variation in the type and not the amount of starch in the diet.
INTRODUCTION
Abstract
Introduction
Methods
Results
Discussion
References
), possibly leading to a deterioration in diabetic control and carrying an inherent risk in selected individuals.
) report or suggest that the type of starch present in the carbohydrate is a potential factor in the glycemic response. Previously, we showed that a high amylopectin starch (waxy cornstarch, WCS)4 diet induced postprandial hyperglycemia and hyperinsulinemia as well as an increase in adipose tissue lipogenesis after 3 wk, in diabetic and even in normal rats (Kabir et al. 1998). Over a longer period (5 wk), another high glycemic index starch diet that contained wheat starch was found to increase adiposity and triglycerides (Lerer-Metzger et al. 1996), again in both normal and diabetic rats. These results suggest that this type of diet may prove harmful even in normal animals; the repeated high glycemic and insulinemic responses might result in a shift to a more diabetogenic or atherogenic plasma profile. In addition, adipose tissue might be a major target for the effect of high glycemic index starch diets on glucose utilization and lipid metabolism via postprandial hyperglycemia and hyperinsulinemia found with this type of diet (Kabir et al. 1998). Thus, it could be questioned whether the chronic postprandial hyperglycemia and hyperinsulinemia due to a high glycemic index starch diet induce the genes implicated in adiposity and lipogenesis, an effect that could be deleterious. To address this problem, we studied the effect of a high vs. a low glycemic index starch diet on some lipid storage-related enzymes regulated by insulin, i.e., fatty acid synthase (FAS) and lipoprotein lipase (LPL), in both normal and noninsulin-dependent diabetic rats.
, Hillgartner et al. 1995). As a rule, high carbohydrate, fat-free diets stimulate lipogenesis at least in the liver, whereas starvation has an inhibitory effect (Clarke et al. 1990). Hormonal factors involved in the regulation of lipogenesis such as insulin, glucagon and thyroid hormone interact with these nutritional controls to achieve lipid homeostasis. This homeostasis is reached by altering the activity and gene expression of key lipogenic enzymes, particularly acetyl-CoA carboxylase and FAS (Clarke et al. 1990, Katsurada et al. 1990a and 1990b, Volpe and Vagelos 1976).
).
). This model is also characterized by mild hypoinsulinemia in fed rats, but a lack of insulin release in response to glucose in vivo (Portha et al. 1989). There is some capacity for 
-cell regeneration, and rats could survive without insulin therapy. The defects in insulin secretion and action that develop in this model in some ways resemble those described in human noninsulin-dependent diabetics. This model appears to be well-suited to study the effects of modulating dietary factors involved in the development and/or deterioration of noninsulin-dependent diabetes.
MATERIALS AND METHODS
Abstract
Introduction
Methods
Results
Discussion
References
and Portha et al. (1989). Normal rats used as controls were injected with an equivalent volume of vehicle buffer.
, (semisynthetic modified powder no. 210, fabricated by the UAR, Usine d'Alimentation Rationnelle, Villemoisson-sur-Orge, France, Table 1). The MBS consisted of cooked and powdered Chinese noodles, Pagoda Brand, manufactured in the Republic of China, purchased from local Asian supermarkets in France and prepared by Nestlé, Switzerland. The WCS was from Cerestar (Benelux, Breda, Netherlands). Daily food intake was determined and rats were weighed at the beginning of the dietary period and at the end of each week.
View this table:
Table 1.
Composition of experimental diets
20°C for further plasma glucose, insulin and lipid measurements. Epididymal fat pads, skeletal muscle (gastrocnemius and soleus) and liver were immediately removed and weighed. Samples were homogenized immediately to determine FAS activity in epididymal adipose tissue and liver, whereas LPL activity was measured in epididymal adipose tissue and muscle. Other samples were immediately frozen in liquid nitrogen. Tissues were then stored at 80°C for later gene expression studies.
. One unit of enzyme represents the oxidation of 1 nmol NADPH per minute at 37°C. Protein concentration was measured by using bovine serum albumin as standard (Bradford 1976). The results were expressed as mU/mg protein.
). After centrifugation (1500 × g, 10 min at 4°C), the clear solution between the floating fat layer and the precipitated nuclei and red blood cells was aspirated and diluted (
). Aliquots (100 µL) were used to determine the LPL activity according to Nilsson-Ehle and Schotz (1976) by using an artificial emulsion of 14C-triolein (Amersham, les Ulis, France). One unit of LPL activity corresponds to 1 nmol free fatty acid released during 1 h. LPL activity was expressed as U/g tissue for both skeletal muscle and adipose tissue.
, with the use of an RNA plus kit (Bioprobe Systems, Montreuil-Sous-Bois, France).
-actin, and water to 25 µL samples. Then, 25 µL mineral oil (Sigma Chemical, St. Louis, MO) was added. cDNA were then denatured for 5 min at 92°C and amplified (92°C, 1 min; 58°C, 1 min 30 s; 72°C, 1 min 30 s) followed by a final extension of 7 min at 72°C in a thermal cycler (Techne PHC-3 Thermal cycler, Oxford, UK). The amount of template and the number of cycles were chosen in the exponential phase to allow semiquantitative measurements. Samples from adipose tissue, 75 ng and 150 ng in normal and diabetic rats, respectively; 200 ng of cDNA from liver was coamplified as described above. cDNA were amplified only in presence of FAS primers for 7 cycles and in the presence of both FAS and -actin primers for the remaining 23 cycles. Sequences of sense and antisense oligonucleotides were: 5'-CAGCTGACATTTCATCAGGCCA-3' and 5'-ATGGATATCTGCAGCATTGTGTCC-3' for FAS; 5'-GAGACCTTCAACACCCC-3' and 5'-GTGGTGGTGAAGCTGTAGCC-3' for -actin. The oligonucleotides of FAS were derived from the sequences of corresponding genes and cDNA (Amy et al. 1989). The PCR products (370 and 236 Bq for FAS and -actin, respectively) were separated on 2% agarose gel, visualized by ethidium bromide staining, and signals were analyzed and quantified by scanning densitometry using NIH image 1.56 software. FAS signals were normalized to those of -actin.
-32p] dCTP by using a multiprime DNA labeling system Kit (Amersham). Epididymal adipose tissue glucose transporter (GLUT4) mRNA was hybridized with a rat rRNA probe prepared from a plasmid provided by M. J. Charron (Vanderbilt University, Nashville, TN) (Charron et al. 1989), under stringent conditions. Northern blots were then hybridized with an oligonucleotide specific for 18S ribosomal RNA labeled with 
[32P] ATP to control the amount of total RNA loaded on the gel. Quantification was performed by scanning densitometry and corrected for variations of the amount of RNA loaded by the 18S rRNA values.
RESULTS
Abstract
Introduction
Methods
Results
Discussion
References
View this table:
Table 2.
Food intake, body and epididymal adipose tissue weights and plasma glucose, insulin and lipid concentrations in normal and diabetic rats after 3 wk of consuming diets containing 575 g/kg mung bean starch or waxy cornstarch1
, Lerer-Metzger et al. 1996) and those of others studying this type of diabetes (Bonner-Weir et al. 1981, Portha et al. 1989).
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Fig 1.
Plasma glucose and insulin response curves after an intraperitoneal glucose challenge (2 g glucose /kg body weight) in normal (N) and diabetic (D) rats fed a waxy cornstarch (WCS)- or mung bean starch (MBS)-containing diet for 3 wk. Values are means ± SEM, n = 12.
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[in a new window]
Fig 2.
Fatty acid synthase (FAS) expression measured by semiquantitative reverse transcription-polymerase chain reacion (RT-PCR) in the epididymal adipose tissue (left panel) and liver (right panel) of normal and diabetic rats fed the waxy cornstarch or the mung bean starch diet for 3 wk. The FAS values were normalized to those of -actin.Values are means ± SEM, n = 6-8/group; *P < 0.05 between diet groups.
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[in a new window]
Fig 3.
Phosphoenolpyruvate carboxykinase (PEPCK) expression measured by Northern-blot analysis in the liver of normal and diabetic rats fed the waxy cornstarch or mung bean starch diet for 3 wk. The PEPCK values were normalized to those of 18 S. Values are means ± sem, n = 4-5; *P < 0.05 between diet groups.
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Fig 4.
Adipose tissue GLUT4 expression measured by Northern-blot analysis in normal and diabetic rats fed the waxy cornstarch or mung bean starch diet for 3 wk. The GLUT4 values were normalized to those of 18 S. Values are means ± SEM, n = 4-5; *P < 0.05 between diet groups.
DISCUSSION
Abstract
Introduction
Methods
Results
Discussion
References
). That study demonstrated that lipogenesis in normal rats was 160% higher after consuming the WCS than after consuming the MBS diet. In the diabetic rats, which were less sensitive to dietary effects, the increase in lipogenesis due to WCS was less than that found in normal rats. This is consistent with results of this study in which differences in FAS activity and gene expression due to diet were significant only in normal rats.
, Coupe et al. 1990, Goodridge 1987, Rousseau et al. 1997), changing the type of starch as in this study affected only adipose tissue lipogenesis within 3 wk. Other carbohydrates such as fructose, however, regulated lipogenesis differently, i.e., lipogenesis was shifted from adipose tissue to the liver (Chevalier et al. 1972). When a sucrose diet was supplemented by fish oil (Petit-Jean et al. 1997, Sebokova et al. 1996) or by fructooligosaccharides (Agheli et al. 1998), FAS activity decreased in the liver but increased in the adipose tissue. The explanations for these effects are not clear. Shillabeer et al. (1992) showed that changes in adipose tissue FAS mRNA levels were almost reciprocal with those in hepatic levels. They suggested that the regulation of FAS mRNA levels in adipose tissue may depend on substrate availability rather than on plasma hormonal concentration, which may differ from hepatic regulation. In this study, adipose tissue FAS mRNA was not regulated by substrate availability because there was no variation in plasma triglycerides or free fatty acids after 3 wk of consuming the high glycemic index starch diet. Some authors, however, have demonstrated that adipose tissue FAS mRNA could by regulated by plasma insulin in vivo (Becker et al. 1995, Hillgartner et al. 1995) and in vitro (Foufelle et al. 1992). In this study, although there were no variations in basal insulin levels in normal rats, the consistently high postprandial hyperinsulinemia and hyperglycemia after consumption of the high glycemic index starch diet (Kabir et al. 1998) cannot be excluded as a main factor affecting adipose tissue FAS mRNA in normal rats. This hypothesis is likely. Two arguments in this study strengthen the implication of postprandial insulin peaks. First, hepatic PEPCK expression, which is under negative control of insulin (Cimbala et al. 1982), was strongly inhibited. Becker et al. (1995) found that low plasma insulin concentration during the suckling period was accompanied by high expression of PEPCK, whereas the high plasma glucose and insulin concentration after consumption of a high carbohydrate diet was concomitant with a rapid decrease of PEPCK (Becker et al. 1995). Second, GLUT4 mRNA, another gene positively regulated by insulin in vivo (Hillgartner et al. 1995, Kahn and Flier 1990), was greater in normal rats fed the high rather than the low glycemic index starch diet. In the literature, the increase in lipogenic enzymes and GLUT4 expression in hyperinsulinemic fa/fa rats after weaning (Penicaud et al. 1991) as well as in otherwise normal rats with lesions of the ventromedial hypothalamus (Cousin et al. 1992), was attributed to a large extent to hyperinsulinemia. Similarly, 4 d of insulin treatment in adult STZ-diabetic rats increased both FAS and GLUT4 mRNA levels rapidly and markedly (Becker et al. 1995).
). Taken together, these data suggest that lipogenic enzymes, GLUT4 and glucose-6-phosphate, might be regulated by both postprandial hyperinsulinemia and hyperglycemia. In this study, however, adipose tissue FAS and GLUT4 of diabetic rats seemed to be more resistant to the increased postprandial plasma insulin and glucose values than were those of normal rats.
, Spooner et al. 1979). Similarly, administration of glucose and/or insulin to experimental animals resulted in an increase in the adipose tissue enzyme activity (Grafinkel et al. 1976). In this study, the repeated peaks of insulin after the high glycemic index starch diet were not accompanied by greater adipose tissue LPL activity. This might be due to the presence of large adipocytes, produced by consuming the high glycemic index starch diet (Kabir et al. 1998, Lerer-Metzger et al. 1996), that were less sensitive to the insulin effect (Fried et al. 1990). Moreover, Guy-Grand and Bigorie (1975) demonstrated that the correlation between insulin and LPL activity depends on adipose tissue cell size.
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FOOTNOTES |
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Manuscript received 15 June 1998. Initial reviews completed 1 July 1998. Revision accepted 12 July 1998.
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ACKNOWLEDGEMENTS |
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The authors thank B. Guy-Grand for agreeing to measure plasma lipids in his laboratory and Nestlé Switzerland for the preparation of the powdered mung bean. We express our gratitude to D. K. Granner, Vanderbilt University (Nashville, TN) for offering the pPC116 of rat PEPCK used.
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LITERATURE CITED |
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Abstract
Introduction
Methods
Results
Discussion
References
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