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PubMed1997

Glycogen Formation by the Ruminal Bacterium Prevotella ruminicola.

Prevotella ruminicola is an important ruminal bacteria. In maltose-grown cells, nearly 60% of cell dry weight consisted of high-molecular-weight (>2 x 10(sup6)) glycogen. The ratio of glycogen to protein (grams per gram) was relatively low (1.3) during exponential growth, but when cell growth slowed during the transition to the stationary phase, the ratio increased to 1.8. As much as 40% of the maltose was converted to glycogen during cell growth. Glycogen accumulation in glucose-grown cells was threefold lower than that in maltose-grown cells. In continuous cultures provided with maltose, much less glycogen was synthesized at high (>0.2 per h) than at low dilution rates, where maltose was limiting (28 versus 60% of dry weight, respectively). These results indicated that glycogen synthesis was stimulated at low growth rates and was also influenced by the growth substrate. In permeabilized cells, glycogen was synthesized from [(sup14)C]glucose-1-phosphate but not radiolabelled glucose, indicating that glucose-1-phosphate is the initial precursor of glycogen formation. Glycogen accumulation may provide a survival mechanism for P. ruminicola during periods of carbon starvation and may have a role in controlling starch fermentation in the rumen.

Journal Article↗

PubMed1977

Activation of protein kinase and glycogen phosphorylase in isolated rat liver cells by glucagon and catecholamines.

In liver cells isolated from fed female rats, glucagon (290nM) increased adenosine 3':5'-monophosphate (cyclic AMP) content and decreased cyclic AMP binding 30 s after addition of hormones. Both returned to control values after 10 min. Glucagon also stimulated cyclic AMP-independent protein kinase activity at 30 s and decreased protein kinase activity assayed in the presence of 2 muM cyclic AMP at 1 min. Glucagon increased the levels of glycogen phosphorylase a, but there was no change in total glycogen phosphorylase activity. Glucagon increased glycogen phosphorylase a at concentrations considerably less than those required to affect cyclic AMP and protein kinase. The phosphodiesterase inhibitor, 1-methyl-3-isobutyl xanthine, potentiated the action of glucagon on all variables, but did not increase the maximuM activation of glycogen phosphorylase. Epinephrine (1muM) decreased cyclic AMP binding and increased glycogen phosphorylase a after a 1-min incubation with cells. Although 0.1 muM epinephrine stimulated phosphorylase a, a concentration of 10 muM was required to increase protein kinase activity. 1-Methyl-3-isobutyl xanthine (0.1 mM) potentiated the action of epinephrine on cyclic AMP and protein kinase. (-)-Propranolol (10muM) completely abolished the changes in cyclic AMP binding and protein kinase due to epinephrine (1muM) in the presence of 0.1mM 1-methyl-3-isobutyl xanthine, yet inhibited the increase in phosphorylase a by only 14 per cent. Phenylephrine (0.1muM) increased glycogen phosphorylase a, although concentrations as great as 10 muM failed to affect cyclic AMP binding or protein kinase in the absence of phosphodiesterase inhibitor. Isoproterenol (0.1muM) stimulated phosphorylase and decreased cyclic AMP binding, but only a concentration of 10muM increased protein kinase. 1-Methyl-3-isobutyl xanthine potentiated the action of isoproterenol on cyclic AMP binding and protein kinase, and propranolol reduced the augmentation of glucose release and glycogen phosphorylase activity due to isoproterenol. These data indicate that both alpha- and beta-adrenergic agents are capable of stimulating glycogenolysis and glycogen phosphorylase a in isolated rat liver cells. Low concentrations of glucagon and beta-adrenergic agonists stimulate glycogen phosphorylase without any detectable increase in cyclic AMP or protein kinase activity. The effects of alpha-adrenergic agents appear to be completely independent of changes in cyclic AMP protein kinase activity.

Animals↗

PubMed2000

Evidence for a functional glycogen metabolism in mature mammalian spermatozoa.

The glycogen content in fresh raw dog spermatozoa was 0.22+/-0.03 micromol/mg protein. This matched with the presence of a glycogen-like staining in the head and midpiece. Glycogen levels lowered to 0.05 micromol/mg protein after incubation for 60 min without sugars. Addition of either 10 mM fructose or 10 mM glucose increased glycogen content to 0.70 micromol/mg protein. On the other hand, glycogen synthase activity ratio of fresh dog sperm (0.35+/-0.07, measured in the absence and the presence of glucose 6-P) increased to 0.55 with 10 mM fructose for 20 min, whereas glucose had a smaller effect. Spermatozoa extracts had also a protein of about 100 Kd, which reacted against a rat liver glycogen synthase antibody. This was located in sperm head and midpiece. Furthermore, glycogen phosphorylase activity ratio measured in presence and absence of AMP (0.25+/-0.03 in fresh samples) decreased to 0.15 by 10 mM glucose for 20 min, whereas fructose was less potent in this regard. The maximal effect of glucose and fructose were observed from 10-20 mM onwards. This work is the first indication for a functional glycogen metabolism in mammal spermatozoa, which could play an important role in regulating sperm survival in vivo.

Animals↗

PubMed1993

Localization of glycogen synthase activity in liver of fasted normal and adrenalectomized rats after injection of dexamethasone.

Hepatic glycogen synthase activity was localized in normal and adrenalectomized (ADX) rats after fasting overnight and in fasted ADX rats after injection of dexamethasone (DEX) 2-8 h prior to sacrifice to stimulate glycogen synthesis. Cryostat sections were incubated in medium containing substrate to demonstrate glycogen synthase activity as indicated by glycogen synthesized during incubation. Sections from fasted normal rats showed limited dispersed glycogen synthase activity in both periportal and centrilobular regions. In contrast, activity for glycogen synthase in hepatocytes from fasted ADX rats appeared as large aggregates in random hepatocytes throughout the lobule. Two hours after injection of DEX the reaction product appeared as aggregates in some hepatocytes, but other cells revealed dispersed enzyme activity. Glycogen synthase activity was evident in more hepatocytes after 4 h treatment with DEX and after 8 h virtually all hepatocytes contained abundant reaction product. The results suggest that synthase activity becomes concentrated in limited regions of selected hepatocytes in fasted ADX rats. DEX stimulation of glycogen synthesis for 4-8 h results in increased enzyme activity.

Adrenalectomy↗

PubMed1977

Glycogen metabolism in adult rat liver parenchymal cell primary cultures.

Parenchymal cells were isolated from adult rat liver with an enzyme perfusion technique. The single-cell suspension, representing 40-50% of the liver's hepatocytes was suspended in medium and maintained in primary culture for up to four days. The cells were found to carry out glycogen synthesis for the first eight hours in culture after which time the accumulated glycogen was gradually degraded. The ability of the liver cell cultures to accumulate glycogen was found to be dependent upon the metabolic state of the animal prior to cell isolation. Cells prepared during the feeding period from animals on the 8+16 feeding schedule had markedly different capacities for glycogen accumulation. Changes in glycogen metabolism were found to be due, in part, to changes in the fraction of cells involved in metabolism at any given time. High concentrations of glucose stimulated the cells to deposit glycogen but the response was reduced the longer the cells were in culture over a 3-day period. This loss of glycogen synthesizing capacity appears to be due to a decrease in glycogen synthetase activity. The activities of pyruvate kinase, hexokinase and aldolase also decrease during the culture period.

Animals↗

PubMed1980

Effects of insulin on glycogen metabolism of serum-deprived BHK-21 fibroblasts.

We have studied the effects of insulin on glycogen metabolism of cultured BHK-21 fibroblasts. Addition of insulin to cells cultured in 0.5% serum stimulated incorporation of 5mM 14C-glucose into glycogen and increased cellular glycogen content, without inducing proliferation. With serum-deprived cells incubated for 2 hr, maximal stimulation of incorporation of glucose into glycogen was 3.5-fold and the half-maximal dose of insulin was 5nM. After culture for 24 hr with 100nM insulin, incorporation was increased 13-fold and glycogen content was increased by 44%. Incorporation of glucose into glycogen was reduced by agents which elevate cellular adenosine 3',5-cyclic monophosphate (cyclic AMP): 10 microM prostaglandin E1 (PGE1), 0.25 mM 1-methyl-3-isobutylxanthine (MIX), 10 microM L-epinephrine (L-EPI), and 10 microM L-isoproterenol (L-ISO). Culture with 100nM insulin for 2 hr stimulated incorporation three-fold in the presence of any of these compounds, but insulin did not affect cellular cyclic AMP. At all times from 1 hr to 24 hr after addition of insulin to serum-deprived cultures, the 1-min uptake of 10 microM 3H-2-deoxyglucose (3H-2DG) was increased. There were small (30 to 40%) increases in glycogen synthase I activity at 15 and 30 min but not 4 hr after addition of insulin. After 24 hr with insulin, total glycogen synthase and phosphorylase activities were increased approximately two-fold, without changes in their activation states. We conclude that insulin promotes glycogenesis in serum-deprived BHK-21 cells. This response is mediated principally by increased entry of glucose into cells, and is not mediated by a change in cellular cyclic AMP concentration.

Cell Line↗

PubMed2005

Glucocorticoid-induced insulin resistance in skeletal muscles: defects in insulin signalling and the effects of a selective glycogen synthase kinase-3 inhibitor.

AIMS/HYPOTHESIS: Treatment with glucocorticoids, especially at high doses, induces insulin resistance. The aims of the present study were to identify the potential defects in insulin signalling that contribute to dexamethasone-induced insulin resistance in skeletal muscles, and to investigate whether the glycogen synthase-3 (GSK-3) inhibitor CHIR-637 could restore insulin-stimulated glucose metabolism. MATERIALS AND METHODS: Skeletal muscles were made insulin-resistant by treating male Wistar rats with dexamethasone, a glucocorticoid analogue, for 12 days. Insulin-stimulated glucose uptake, glycogen synthesis and insulin signalling were studied in skeletal muscles in vitro. RESULTS: Dexamethasone treatment decreased the ability of insulin to stimulate glucose uptake, glycogen synthesis and glycogen synthase fractional activity. In addition, the dephosphorylation of glycogen synthase by insulin was blocked. These defects were paralleled by reduced insulin-stimulated protein kinase B (PKB) and GSK-3 phosphorylation. While expression of PKB, GSK-3 and glycogen synthase was not reduced by dexamethasone treatment, expression of the p85alpha subunit of phosphatidylinositol 3-kinase (PI 3-kinase) was increased. Inhibition of GSK-3 by CHIR-637 increased glycogen synthase fractional activity in soleus muscle from normal and dexamethasone-treated rats, although the effect was more pronounced in control rats. CHIR-637 did not improve insulin-stimulated glucose uptake in muscles from dexamethasone-treated rats. CONCLUSIONS/INTERPRETATION: We demonstrated that chronic dexamethasone treatment impairs insulin-stimulated PKB and GSK-3 phosphorylation, which may contribute to insulin resistance in skeletal muscles. Acute pharmacological inhibition of GSK-3 activated glycogen synthase in muscles from dexamethasone-treated rats, but GSK-3 inhibition did not restore insulin-stimulated glucose uptake.

Animals↗

PubMed2005

Compartmentation of lactate originating from glycogen and glucose in cultured astrocytes.

Brain glycogen metabolism was investigated by employing isofagomine, an inhibitor of glycogen phosphorylase. Cultured cerebellar and neocortical astrocytes were incubated in medium containing [U-(13C)]glucose in the absence or presence of isofagomine and the amounts and percent labeling of intra- and extracellular metabolites were determined by mass spectrometry (MS). The percent labeling in glycogen was markedly decreased in the presence of isofagomine. Surprisingly, the percent labeling of intracellular lactate was also decreased demonstrating the importance of glycogen turnover. The decrease was limited to the percent labeling in the intracellular pool of lactate, which was considerably lower compared to that observed in the medium in which it was close to 100%. These findings indicate compartmentation of lactate derived from glycogenolysis and that derived from glycolysis. Inhibiting glycogen degradation had no effect on the percent labeling in citrate. However, the percent labeling of extracellular glutamine was slightly decreased in neocortical astrocytes exposed to isofagomine, indicating an importance of glycogen turnover in the synthesis of releasable glutamine. In conclusion, the results demonstrate that glycogen in cultured astrocytes is continuously synthesized and degraded. Moreover, it was found that lactate originating from glycogen is compartmentalized from that derived from glucose, which lends further support to a compartmentalized metabolism in astrocytes.

Amino Acids↗

PubMed1983

Comparative effects of insulin and hydrocortisone on glycogen content of fetal and newborn rat liver cultures.

Organ cultures prepared from 18- to 19-day fetal and 3- to 6-day-old newborn rat liver were maintained for 2 days in Trowell's T8 medium without insulin and supplemented with 0.1% albumin and 300 mg% glucose. The atmosphere for culture was 95% O2 and 5% CO2. Medium alone was used for control cultures, whereas insulin, hydrocortisone, or insulin plus hydrocortisone were used in experimental groups. Explant glycogen stores were maintained better in cultures grown in hormone-supplemented media than in control cultures. Fetal explants were found to have higher levels of glycogen than controls in the insulin or insulin plus hydrocortisone groups. Postnatal explants did not have higher levels of glycogen in the hormone-treated groups. Gestational age appeared to determine whether the liver explants reacted to hydrocortisone or insulin to maintain glycogen stores. Enzymatic assays, in vitro of glycogen synthetase and phosphorylase, indicated that the fetal liver response to insulin plus hydrocortisone by increasing the total and independent form of glycogen synthetase; but similar enzyme studies on postnatal rat liver did not show convincing differences as to an effect on synthetase. No definite in vitro temporal relationships could be identified. Late in gestation, the effect of hydrocortisone on glycogen synthesis is apparently dependent on the presence of insulin. Insulin appears to be required for glycogen storage in vitro in the cultures of postnatal rat liver.

Animals↗

PubMed1984

Glycogen regulation in LPS-stimulated murine splenocytes.

Enzymatic glycogen regulation in mouse splenocytes cultured in vitro with and without LPS, was studied from 0-72 h. Increased [3H]glucose uptake and hexokinase activity demonstrated the activation of cells treated with LPS. There was a greater time-dependent increase of cellular glycogen content in LPS-stimulated cells as compared to control. Glycogen synthetase I in LPS-stimulated cells increased about 200% above control cells to a plateau at 48 h, while in unstimulated cells there was little increase throughout. Glycogen synthetase D increased continually to 72 h in both groups. In the stimulated cells, phosphorylase increased only 90% above control cells up to 48 h. It was concluded that the increased glycogen content of LPS-stimulated cells seen at 48 h may result from an increase in both glycogen synthetase I and D activity compared to lesser increase in hydrolysis. However, between 48 and 72 h, the period of RNA and DNA increased synthesis, the glycogen content of stimulated cells did not increase further, consistent with the observation that synthetase I activity remained constant and synthetase D decreased. Thus, following mitogenic stimulation, the net effect of the enzymatic regulation is to increase cellular glycogen, as an energy source for subsequent events.

Animals↗

PubMed1991

Proglycogen: a low-molecular-weight form of muscle glycogen.

We recently reported that muscle contains a trichloroacetic acid-precipitable component having Mr approx. 400 kDa that can be glucosylated by an endogenous enzyme acting on UDPglucose. This component contains within itself the autocatalytic, self-glucosylating protein glycogenin, the primer for glycogen synthesis. We now report that this substance, to which we give the name proglycogen, is a glycogen-like molecule constituting about 15% of total glycogen. It acts as a very efficient acceptor of glucose residues added from UDPglucose. Further, that the endogenous enzyme that adds the glucose to proglycogen is not the autocatalytic protein but a glycogen synthase-like enzyme. Proglycogen may be an intermediate in the synthesis and degradation of macromolecular glycogen and may exist and be metabolized as a separate entity. Consideration should now be given to the revival of the concept that tissue contains two forms of glycogen. One is proglycogen. The other is the 'classical', macromolecular glycogen. Additionally, proglycogen and glycogen may be glucosylated by different forms of synthase.

Amylases↗

PubMed1991

Glycogen hyperaccumulation in Saccharomyces cerevisiae ras2 mutant. A biochemical study.

The mechanism by which yeast ras2 mutant hyperaccumulates glycogen has been investigated. Total glycogen synthase activity was between 2.5 and 1.3 times higher in the ras2 mutant than in an isogenic strain. In addition, while in the normal strain the glycogen synthase activation state decreased along the exponential phase, in the mutant strain the opposite behaviour was observed: glycogen synthase activation state rose continuously reaching full activation at the beginning of the stationary phase. Glycogen phosphorylase a activity was up to 40 times higher in the mutant than in the normal strain. Glucose 6-phosphate and fructose 2,6-bisphosphate levels were slightly more elevated in the mutants. The increase in total glycogen synthase and, particularly, the full activation of this enzyme may explain glycogen hyperaccumulation in the ras2 mutant even in the presence of elevated levels of glycogen phosphorylase a.

Cyclic AMP↗

PubMed1990

Non-hormonal and hormonal control of glycogen metabolism in isolated sheep liver cells.

1. Control of glycogen metabolism by various substrates and hormones was studied in ruminant liver using isolated hepatocytes from fed sheep. 2. In these cells glucose appeared uneffective to stimulate glycogen synthesis whereas fructose and propionate activated glycogen synthase owing to (i) a decrease in phosphorylase a activity and (ii) changes in the intracellular concentrations of glucose 6-phosphate and adenine nucleotides. 3. The activation of hepatic glycogenolysis by glucagon and alpha 1-adrenergic agents was associated with increased phosphorylase a and decreased glycogen synthase activities. 4. The simultaneous changes in these two enzyme activities suggest that in sheep liver, activation of phosphorylase a is not a prerequisite step for synthase inactivation. 5. In sheep hepatocytes, in the presence of propionate and after a lag period, insulin activated glycogen synthase without affecting phosphorylase a. 6. This latter result suggests that the direct activation of glycogen synthase by insulin is mediated by a glycogen synthase-specific kinase or phosphatase. Insulin also antagonized glucagon effect on glycogen synthesis by counteracting the rise of cAMP.

Animals↗

PubMed1984

Effects of age on glycogen synthase and phosphorylase activities in rat liver.

The activities of glycogen synthase and phosphorylase were determined in homogenates and subcellular fractions of liver from young adult (6 months' old), adult (12 months' old) and aged (24 months' old) rats. The specific activities (enzyme activity expressed as units per mg protein) of the active form of glycogen synthase (synthase a) as well as of total synthase (synthase a + b) were significantly lower in liver homogenates of aged compared to young adult or adult rats. The age-associated decrease in the specific activity of synthase a was most marked in the 10 000 g and 100 000 g particulate fractions of liver. The specific activities of the active form of phosphorylase (phosphorylase a) as well as of total phosphorylase (phosphorylase a + b) were also significantly lower in liver homogenates of aged compared to young adult or adult animals. The age-related decrease in the specific activity of phosphorylase a was most pronounced in the 10 000 g particulate fraction of liver. Analysis of the specific activity ratios of glycogen synthase a/glycogen synthase a + b indicated a disproportionately greater age-related decrement in the active form of this enzyme. No such age-related difference was evident in the specific activity ratios of phosphorylase a/phosphorylase a + b. The age-associated decrease in the activities of glycogen synthase (a or a + b) and phosphorylase (a or a + b) was also discernible when the enzyme activities were expressed as units per g liver; this decrement in enzyme activity was reflected in all subcellular fractions examined. The levels of plasma insulin, plasma glucose and liver glycogen were not significantly different in rats of the three age groups used in these studies. The reduced activities of liver glycogen synthase and phosphorylase in aged rats is indicative of a likely diminution in the turnover of glycogen in liver during aging. Such an age-associated deficit in liver glycogen metabolism may contribute, at least in part, to the generally observed glucose intolerance upon aging.

Aging↗

PubMedDate not supplied

Glycogen content of placenta and of fetal and maternal liver in cadmium-exposed rats. I: A descriptive light microscopic study.

Female Wistar rats were injected subcutaneously with CdCl2 (0.49 mg Cd/kg/day) daily during pregnancy. Placentae, fetal livers and maternal livers were prepared for histological investigation of the glycogen content 14, 16, 18, 19 and 20 days after mating. The glycogen content was estimated semiquantitatively in periodic acid-Schiff-(PAS-)stained sections. The development of the glycogen content of the placenta and the fetal liver from days 14 to 20 of pregnancy in control animals is described and compared with the development of the glycogen content of these tissues from cadmium-exposed animals. No clear changes due to cadmium exposure were observed in the glycogen content of maternal and fetal livers, nor in the spongiotrophoblast and the islets of glycogen in the placenta. The glycogen content in the placental labyrinth increased from day 14 up to day 18 in both control and cadmium-exposed animals. In control animals, the glycogen content decreased after day 18, whereas it remained high in the placental labyrinth of cadmium-exposed animals; this might be considered as a feature of retarded maturation. Regulating mechanisms and similarities between the effects of cadmium exposure and the diabetic state are discussed.

Animals↗

PubMed1982

A comparative study of trout and chicks regarding dietary effects on glycogen concentration in liver and muscle during feeding and subsequent to feed withdrawal.

1. Glycogen concentrations in liver and skeletal muscle were compared in rainbow trout and in chicks of two genetic sources. 2. Tissue glycogen concentrations were determined during feeding and after feed withdrawal in response to diets high in carbohydrate and oil, respectively. 3. Livers of trout and chicks were heavier and glycogen concentrations were higher in both liver and muscle of trout and chicks fed high-carbohydrate diets. 4. Feed withdrawal resulted in gradual but steady declines in trout glycogen over a 16-day period but caused sharp declines in liver glycogen in chicks followed by a rebound and a more gradual decline within a 5-day period. 5. Feed withdrawal from trout caused declines in muscle glycogen followed by rebounds which occurred more rapidly when the high-carbohydrate diet had been fed. 6. Feed withdrawal had little effect on muscle glycogen in broiler-type chicks. In White Leghorn chicks there was a general decline in muscle glycogen which showed marked fluctuations when the high-fat diet had been fed.

Animal Feed↗

PubMed1980

Influence of insulin, glucocorticoids and glucose on glycogen synthase activity in hepatocyte cultures.

A preparation method of monolayer cultures from rat hepatocytes with up to 95% plating efficiency is described. Cell number and DNA content per dish remained stable during 3 days in culture in hormone-free media containing 10 mM glucose. The cellular content of protein was decreased to 50% in the same time period. Glycogen content and specific activity of glycogen synthase present in the original hepatocyte suspension declined rapidly during 2 days in the absence of hormones. Addition of 20 nM insulin or 0.1 microM triamcinolone did not prevent this loss of cellular contents, however, in the simultaneous presence of both hormones the original levels of protein, glycogen and glycogen synthase were maintained for 2 days. In 2-day-old hepatocytes an increase of glycogen synthase activity could be evoked by insulin in the presence of 20 or even 5 mM glucose provided these cells had been precultivated in the presence of triamcinolone. Both the I-form and the activity determined at 6.7 mM glucose 6-phosphate rose after exposition of hepatocytes to insulin and 20 mM glucose, whereas a 'total activity' being unchanged by hormone treatment of the cells was only obtained if 50 mM glucose 6-phosphate were present during determination of enzyme activity. Addition of 10 microgram/ml cycloheximide during incubation of the cells reduced the effect of 20 mM glucose and abolished that of insulin on glycogen synthase and on the corresponding glycogen deposition. It is discussed that insulin and glucose activate glycogen synthase in two successive steps by regulating synthesis and activity of an interconverting enzyme.

Animals↗

PubMed2003

Control of glycogen deposition.

Traditionally, glycogen synthase (GS) has been considered to catalyze the key step of glycogen synthesis and to exercise most of the control over this metabolic pathway. However, recent advances have shown that other factors must be considered. Moreover, the control of glycogen deposition does not follow identical mechanisms in muscle and liver. Glucose must be phosphorylated to promote activation of GS. Glucose-6-phosphate (Glc-6-P) binds to GS, causing the allosteric activation of the enzyme probably through a conformational rearrangement that simultaneously converts it into a better substrate for protein phosphatases, which can then lead to the covalent activation of GS. The potency of Glc-6-P for activation of liver GS is determined by its source, since Glc-6-P arising from the catalytic action of glucokinase (GK) is much more effective in mediating the activation of the enzyme than the same metabolite produced by hexokinase I (HK I). As a result, hepatic glycogen deposition from glucose is subject to a system of control in which the 'controller', GS, is in turn controlled by GK. In contrast, in skeletal muscle, the control of glycogen synthesis is shared between glucose transport and GS. The characteristics of the two pairs of isoenzymes, liver GS/GK and muscle GS/HK I, and the relationships that they establish are tailored to suit specific metabolic roles of the tissues in which they are expressed. The key enzymes in glycogen metabolism change their intracellular localization in response to glucose. The changes in the intracellular distribution of liver GS and GK triggered by glucose correlate with stimulation of glycogen synthesis. The translocation of GS, which constitutes an additional mechanism of control, causes the orderly deposition of hepatic glycogen and probably represents a functional advantage in the metabolism of the polysaccharide.

Animals↗