The role of glycogen phosphorylase in the regulation of glycogenolysis by insulin and glucagon in isolated eel (Anguilla rostrata) hepatocytes   总被引：1，自引：0，他引：1  

Glen D. Foster  T. W. Moon 《Fish physiology and biochemistry》1990,8(4):299-309

The effects of porcine, scombroid, and salmon insulins, and bovine and anglerfish glucagons on glycogen depletion and glycogen phosphorylase (GPase) activities were examined in freshly isolated American eel (Anguilla rostrata) hepatocytes. Eel liver GPase in crude homogenates was activated (increase in % GPase a) by phosphorylating conditions and was rapidly inactivated (less than 1 h) when a phosphatase inhibitor (fluoride) was absent. Caffeine inhibits, and AMP activates, the b form of GPase consistent with their effects on rat liver GPase. Both mammalian and fish glucagons increased glucose production in eel hepatocytes, but had more ambiguous effects on glycogen levels and GPase activities. The magnitude of bovine glucagon effects were dependent on the initial glycogen content of the cells; only at glycogen concentrations less than approximately 70 μmoles.g⁻¹ did glucagon significantly increase % GPase a. Anglerfish glucagon significantly increased cyclic AMP (cAMP) concentrations by 90% at 10⁻⁷ M, but had no effects at 10⁻⁹ M and 10⁻⁸ M. Scombroid and salmon insulins maintained hepatocyte glycogen concentrations and decreased glucose production, with these effects more pronounced at low (10⁻⁹ to 10⁻⁸ M) rather than high (10⁻⁷ M) hormone concentrations. Porcine and salmon insulins decreased total GPase and % GPase a activities, and salmon insulin decreased CAMP levels, but only at 10⁻⁸ M (by 44%). Glycogen is, therefore, depleted by glucagon and maintained by insulin in freshly isolated American eel hepatocytes, and these changes are accomplished, at least in part, by changes in the activities of GPase. Changes in cAMP do not explain all of the observed hormone effects.  相似文献   

Insulin binding to isolated hepatocytes of Atlantic salmon and rainbow trout     

Erika M. Plisetskaya  Elena Fabbri  Thomas W. Moon  Joaquim Gutiérrez  Celestina Ottolenghi 《Fish physiology and biochemistry》1993,11(1-6):401-409

The questions addressed in this study were: 1) whether insulin added to the incubation medium can down-regulate ¹²⁵I insulin binding to isolated hepatocytes of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss); 2) whether quantitative assessment of insulin processing can be made on isolated fish liver cells; 3) how ambient temperatures can affect insulin binding, and down-regulation of insulin receptors. After isolation and a short (up to 4h) “metabolic recovery period”, liver cells were used either directly in ¹²⁵I insulin binding assay or first preincubated for 18h at 4°C or for 3h at 15°C, with or without mammalian or salmon insulin in concentrations ranging from 1 to 1000 nM. Preincubation at 15°C, decreased binding capacity (number of binding sites per liver cell) in all five independent hepatocyte preparations treated with 1000 nM insulin and in four out of five preparations treated with 100 nM insulin. At 4°C insulin binding sites were down-regulated in less than 50% of all hepatocyte preparations and only in the presence of 1000 nM insulin. Differential quantitive assessment was made of a) intact free insulin; b) insulin degraded; c) intact insulin bound to the cell membrane; d) internalized but degraded insulin, and e) intact insulin internalized by liver cells. Hepatocytes preincubated with 100 – 1000 nM insulin at 15°C bound and internalized less ¹²⁵I insulin. We hypothesize that in vivo, at water temperatures of 15°C and higher, extreme physiological levels of plasma insulin may regulate the numbers of insulin receptors in the salmonid liver. In contrast, in fish inhabiting cold waters the regulation of insulin receptors by circulating plasma insulin seems to be of little physiological importance. Presented in part at the Western Regional Conference on Comparative Endrocrinology, Tempe, Arizona, U.S.A., 1991 and at the Meeting of Italian Society of Experimental Biology, Sorrento, Italy, 1991. Supported by grants from NSF of the USA#DCB 8915935 to E.M.P., NSERC of Canada OPGA 6944 to T.W.M., North Atlantic Treaty Organization (NATO) grant #0926/87 to C.O. and E.M.P., and CYCIT grant of Spain to J.G.  相似文献   

Actions of epinephrine on the contractility of fast and slow skeletal muscle fibres in teleosts     

T. P. Johnson  T. W. Moon  I. A. Johnston 《Fish physiology and biochemistry》1991,9(1):83-89

Fast and slow muscle fibers were isolated from the myotomes of atlantic cod (Gadus morhua L.) and sculpin (Myoxocephalus scorpius L.). Epinephrine was found to have no effect on twitch or sub-tetanic contractions in fast muscle fibres. Isoprenaline (10^–6M) had no effect on the contractility of slow muscle fibres. In contrast, epinephrine elicited a dose-dependent decrease in the half-time for twitch relaxation (t_1/2r), and in most cases a decrease in twitch amplitude. The maximum decrease in t_1/2r was around 5–20% of control values (at 10^–6M epinephrine), with a half maximal response at about 30 nmol l^–1. Responses to epinephrine were unaffected by propranolol and reversed by phentolamine, consistent with the stimulation of -adrenoreceptors. 10^–6M epinephrine produced a rise in cAMP levels from 1.8 to 3.1 pmol mg dry wt^–1 in cod slow fibres. However, the cellular mechanism underlying the action of epinephrine is unclear since forskolin, a potent activator of adenylate cyclase activity, where it has been investigated, was found to increase not decrease twitch duration and amplitude. The responses of fast and slow fibres to epinephrine and its antagonists were similar in summer (13°C) and winter acclimatized (5–6°C) sculpin.It is suggested that epinephrine may act to modulate the active state of slow muscle fibres at high cruising speeds and thereby increase swimming performance.  相似文献   

Endogenous antioxidant systems of two teleost fish,the rainbow trout and the black bullhead,and the effect of age     

Diana M. E. Otto  Thomas W. Moon 《Fish physiology and biochemistry》1996,15(4):349-358

Antioxidant enzyme activities and glutathione status were determined in different tissues of two teleost species, the rainbow trout (Oncorhynchus mykiss) and the black bullhead (Ameiurus melas) to establish whether age-related changes exist between mature and immature individuals. Glutathione reductase and superoxide dismutase activities were significantly lower in hepatic and extrahepatic tissues of 3+ year than 1+ year trout and bullheads. Activities of glutathione peroxidase, catalase and glutathione S-transferase did not exhibit a clear pattern, with decreases in liver and kidney, but increases in gill and muscle tissues. Glutathione concentrations were significantly higher in most tissues of 3+ year than in 1+ year trout, but remained unchanged or decreased in tissues of older bullheads. The results imply an age- or maturation-dependent effect on key antioxidant enzymes in various tissues of these 2 teleost species. Thus, age and maturation may impact upon the use of oxidative stress parameters as indicators of contaminant exposure in environmental studies.  相似文献   

Restricted growth of U-type infectious haematopoietic necrosis virus (IHNV) in rainbow trout cells may be linked to casein kinase II activity     

Park JW  Moon CH  Harmache A  Wargo AR  Purcell MK  Bremont M  Kurath G 《Journal of fish diseases》2011,34(2):115-129

  相似文献   

Metabolic actions of glucagon-family hormones in liver   总被引：1，自引：0，他引：1  

Thomas P. Mommsen  Thomas W. Moon 《Fish physiology and biochemistry》1989,7(1-6):279-288

This review addresses direct and indirect metabolic actions of hormones co-encoded in the preproglucagon gene of fishes. Emphasis is placed on a critical analysis of the effects of glucagon and glucagon-like peptide (GLP) and the current knowledge of the respective modes of action is reviewed. In mammals GLPs exert no direct metabolic actions. In fish liver, GLP and glucagon act on similar targets of intermediary metabolism by enhancing flux through glycogenolysis, lipolysis and gluconeogenesis. Increases in substrate oxidation are not uniform. Hormonal activation of glycogen phosphorylase and triglyceride lipase and inhibition of pyruvate kinase are implicated in these actions. Hormone-dependent hyperglycemia, depletion of hepatic glycogen and increases in free fatty acids are noticeablein vivo. Glucagon also activates hepatic amino acid uptake and ammonia excretion. Glucagon actions are accompanied by large increases in hepatic cAMP and increased phosphorylation of pyruvate kinase. Metabolic effects measured after GLP administration are associated with minor, if any, increases in cAMP and effects on pyruvate kinase are variable. We hypothesize that different hepatic receptors with differing modes of intracellular message transduction are involved in glucagon and GLP actions while targetting identical metabolic routes. Responses of different species of fish cover a wide spectrum, and variation of response with the circannual cycle of experimental animals makes comparisons of results, even within one species, difficult.  相似文献   

Cooperative action of alpha-glucanotransferase and maltogenic amylase for an improved process of isomaltooligosaccharide (IMO) production   总被引：2，自引：0，他引：2  

Lee HS  Auh JH  Yoon HG  Kim MJ  Park JH  Hong SS  Kang MH  Kim TJ  Moon TW  Kim JW  Park KH 《Journal of agricultural and food chemistry》2002,50(10):2812-2817

Maltogenic amylase and alpha-glucanotransferase (alpha-GTase) were employed in an effort to develop an efficient process for the production of isomaltooligosaccharides (IMOs). Bacillus stearothermophilus maltogenic amylase (BSMA) and alpha-GTase from Thermotoga maritima were overexpressed in Escherichia coli using overexpression vectors. An IMO mixture containing 58% of various IMOs was produced from liquefied corn syrup by the hydrolyzing and transglycosylation activities of BSMA alone. When BSMA and alpha-GTase were reacted simultaneously, the IMO content increased to 68% and contained relatively larger IMOs compared with the products obtained by the reaction without alpha-GTase. Time course analysis of the IMO production suggested that BSMA hydrolyzed maltopentaose and maltohexaose most favorably into maltose and maltotriose and transferred the resulting molecules simultaneously to acceptor molecules to form IMOs. alpha-GTase transferred donor sugar molecules to the hydrolysis products such as maltose and maltotriose to form maltopentaose, which was then rehydrolyzed by BSMA as a favorable substrate.  相似文献   

Antimicrobial activity of p-hydroxyphenyl acrylate derivatives     

Kim JH  Park ES  Shim JH  Kim MN  Moon WS  Chung KH  Yoon JS 《Journal of agricultural and food chemistry》2004,52(25):7480-7483

To estimate the antimicrobial effect of p-hydroxyphenyl acrylate (H5) derivatives on the basis of their molecular structure, the hydroxy and acryl groups of p-hydroxyphenyl acrylate were modified. The antimicrobial activity of the resulting compounds was assessed against a Gram-positive bacterium (Staphylococcus aureus), a Gram-negative bacterium (Pseudomonas aeruginosa), and fungi (Aspergillus fumigatus and Penicillium pinphilum) by the halo zone and the shake flask test. The antimicrobial activity of H5 was ascribed mainly to the acryl group. Compounds with acryl or acryloxy groups bound to the phenyl moiety were found to exhibit particularly high antimicrobial activities. The activities of phenyl acrylate and phenyl vinyl ketone were excellent as compared to aliphatic acrylates such as cyclohexyl acrylate and hexyl acrylate, indicating that the stereoelectronic effect of the phenyl group was important to the antimicrobial activity.  相似文献   

H5N1 subtype highly pathogenic avian influenza virus isolated from healthy mallard captured in South Korea     

Kim HR  Kim BS  Bae YC  Moon OK  Oem JK  Kang HM  Choi JG  Lee OS  Lee YJ 《Veterinary microbiology》2011,151(3-4):386-389

On December 7, 2010, H5N1 highly pathogenic avian influenza virus was isolated from a healthy mallard captured at the Mankyung River in South Korea. Phylogenetic analysis showed that this virus was classified into clade 2.3.2 and closely related to H5N1 viruses isolated from wild birds in Mongolia, Russia and China in 2009 and 2010.  相似文献   

Genetic comparison of Brucella canis isolates by the MLVA assay in South Korea     

Kang SI  Heo EJ  Cho D  Kim JW  Kim JY  Jung SC  Her M 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2011,73(6):779-786

The multiple-locus VNTR analysis (MLVA) assay is a method frequently employed as a molecular epidemiological tool for Brucella genetic fingerprinting. The purpose of this study was to assess the genotyping of 77 B. canis isolates from 14 different dog breeding farms in Korea by the MLVA assay and to compare the epidemiological relationships between the Korean isolates and foreign ones. Simpson's diversity index for 17 loci showed a range from 0 to 0.846 in 77 B. canis isolates. B. canis isolates in Korea were observed to have high genetic diversity at the most variable loci and were divided into 30 distinct genotypes by phylogenetic analysis. Some B. canis isolates were closely related to previously typed isolates in other countries. The MLVA assay can be helpful to analyze the epidemiological correlation of B. canis isolates in domestic pet animals and to track the geographic origin by comparing the genetic patterns with foreign isolates. Therefore, the MLVA assay will be useful as a tool for control and preventive measures of canine brucellosis.  相似文献