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Feeding previously fasted perch with a carbohydrate‐rich pelleted diet resulted in a rapid transient insulin response followed by a transient increase in the activity of the hepatic low‐affinity hexokinase (glucokinase, GK). The activity of the high‐affinity hexokinase (hexokinase, HK) increased more slowly and steadily to about seven times the fasting value on the 10th day after start of feeding, in parallel with an increase in the hepatic glycogen content. An insulin response was also observed when fasted perch were fed a diet consisting of boiled fillet of cod (a high‐protein, very low‐fat and practically carbohydrate‐free diet). In this case no GK activity was observed, whereas the glycogen content increased steadily from the start of feeding to about the same level as when fish were given the carbohydrate‐rich diet. There was a delayed increase in the activity of HK, starting on about the sixth day (after the glycogen stores were filled), concomitant with increased activities of lipogenic enzymes (glucose‐6‐phosphate dehydrogenase, ATP citrate lyase and malic enzyme). The results are in line with the hypothesis that the mitochondria‐bound hepatic HK has a particular anabolic function in glycogen and fat synthesis. 相似文献
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寄生海水养殖鱼类的拟格拉夫涡虫的流行、危害与防治 总被引：1，自引：0，他引：1
葡萄糖激酶（GK；E．-C．2．7．1．1）是己糖激酶家族成员，葡萄糖激酶在控制葡萄糖利用率保持葡萄糖平衡方面起着重要的作用。但是，鱼类对糖的利用率却较低，目前对此较公认的解释是由于鱼类肝脏缺乏可诱导的GK活力而不能有效地使细胞内的葡萄糖转化为6-磷酸葡萄糖，可这一解释和现有有关鱼类存在有功能的GK样酶活力以及饲料中碳水化合物对GK表达的诱导作用明显有矛盾。本文报导了从翘嘴红鲐肝脏中分离到的GKcDNA全序列，对其序列进行了比较和分析，为进一步研究翘嘴红鲐GK酶在不同营养条件下的表达奠定基础。 相似文献
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Stefano Moscatello Franco Famiani Simona Proietti Daniela Farinelli Alberto Battistelli 《Scientia Horticulturae》2011
Changes in fruit growth rate, carbohydrate content (glucose, fructose, sucrose and starch) and enzyme activity (sucrose synthase, UDPglucose pyrophosphorylase, fructokinase, glucokinase, sucrose phosphate synthase, ADPglucose pyrophosphorylase and invertases), in the external pericarp of kiwifruit, were measured throughout the growing season. Sucrose synthase showed the highest activity among the sucrose cleaving enzymes during large part of the growing season. The activity of invertases were much lower than that of sucrose synthase until ripening started. Sucrose synthase showed a tight although not linear relationship with the fruit RGR. Furthermore, sucrose synthase showed linear and significant correlations with the activities of both fructokinase and UDPglucose pyrophosphorylase indicating a strong co-regulation of the activities of these three enzymes involved in sucrose cleavage and sink strength, in kiwifruit. Sucrose synthase is suggested to be the dominating enzyme in the cleavage of imported carbon in kiwifruit, in tight coordination with fructokinase and UDPglucose pyrophosphorylase. 相似文献
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Carbohydrates in fish nutrition: effects on growth, glucose metabolism and hepatic enzymes 总被引：20，自引：1，他引：20
The utilisation of dietary carbohydrates and their effects on fish metabolism are reviewed. Details on how dietary carbohydrates affect growth, feed utilisation and deposition of nutrients are discussed. Variations in plasma glucose concentrations emphasizing results from glucose tolerance tests, and the impact of adaptation diets are interpreted in the context of secondary carbohydrate metabolism. Our focus then shifts to selected aspects of hormonal regulation of carbohydrate metabolism and dietary carbohydrates and their variable effects on glycogen and glucose turnover. We analyse the interaction of carbohydrates with other nutrients, especially protein and protein sparing, and de novo synthesis of lipids, and finish by discussing the correlation of dietary carbohydrates with fish health. 相似文献
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Akula Nookaraju Chandrama P. Upadhyaya Shashank K. Pandey Ko Eun Young Se Jin Hong Suk Keun Park Se Won Park 《Scientia Horticulturae》2010
The quality of fruits and vegetables is mainly dependant on the sweetness determined by the level of soluble sugars such as glucose, fructose and sucrose. Other fruit quality parameters include Brix content, acidity, aroma, color, size and shape. Total sugar content in fruits and vegetables is a function of genetic, nutritional, environmental and developmental factors. Understanding the factors controlling sweetness is important to design strategies for enhancing quality of fruits and vegetables. Modifying the activity of enzymes in carbohydrate metabolism such as sucrose synthase (SuSy), acid invertase, ADP-glucose pyrophosphorylase (AGPase), sucrose phosphate synthase (SPS) and sucrose transporters were found to influence carbohydrate partitioning and sucrose accumulation in sink tissues of several food crops. Plant based taste-modifying sweet proteins such as brazzein, cucurmin, mabinlin, monellin, miraculin, neoculin and thaumatin have potential application for developing transgenic plants to improve the sweetness and quality of fruits and vegetables. The present review envisages various cultural, breeding and molecular approaches used for enhancing sugar content and sweetness in fruits and vegetables. 相似文献
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C. Blin S. Panserat F. Médale E. Gomes J. Brèque S. Kaushik R. Krishnamoorthy 《Fish physiology and biochemistry》1999,21(2):93-102
The efficiency of enzymatic conversion of glucose into glucose-6-phosphate in fish fed carbohydrates is still a matter of debate. This study reports the first ever identification of hexokinase-family members at a molecular level in fish. The deduced amino acid sequences of six cDNA clones allowed their assignement either to hexokinase IV (glucokinase) for rainbow trout (Oncorhynchus mykiss), common carp (Cyprinus carpio) and gilthead seabream (Sparus aurata) or to hexokinase I/II for the common carp (two clones) and the gilthead seabream, based on their similarities to known members of the HK family. The evolutionary relationships among these sequences were investigated by phylogenetic analysis. These hexokinase sequences constitute potential molecular tools for analysis of interspecific differences in dietary carbohydrate utilization in fish. 相似文献
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在白色莱航鸡孵化第13d~21d期间,每天随机选取7个-8个胚胎,从中随机选取3个胚胎,分别采肝脏和骨骼肌样品(n=3),用Primer Express2.0(Applied Biosystem)和BLAST(NCBI)软件设计引物,从采取的肝脏和骨骼肌样品中分离出总RNA,采用反转录聚合酶链式反应(RT-PCR)法,合成cDNA。并应用限制性内切酶产物琼脂糖凝胶电泳法和核酸序列分析法对其进行同源性分析和鉴定目的片段。分别对其肝脏和骨骼肌中葡萄糖激酶、己糖激酶-I和己糖激酶-II的mRNA进行定量分析,旨在了解鸡胚胎发育过程中糖酵解关键酶的mRNA表达规律。结果表明:在孵化期的第13d~21d,鸡胚胎肝脏中葡萄糖激酶、己糖激酶-I和己糖激酶-II的mRNA含量均高于骨骼肌中的含量,但差异不显著(p>0.05)。孵化第17d时肝脏中葡萄糖激酶mRNA的含量明显减少(p<0.05),之后缓慢增加,到第21d时其含量仍低于第13d~15d时的含量;肝脏中己糖激酶-I mRNA在孵化第15d明显减少,之后缓慢增加,到孵化第19d时与第13d的含量接近;在孵化第13d~17d期间,肝脏中己糖激酶-II mRNA含量基本没有变化,到孵化第19d时略有升高,但差异均无显著(p>0.05)。骨骼肌中的3个关键酶的mRNA表达,在整个胚胎发育期均无明显的变化(p>0.05)。 相似文献
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Effects of dietary glucose and starch levels on the growth,haematological indices and hepatic hexokinase and glucokinase mRNA expression of juvenile mirror carp (Cyprinus carpio) 
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下载免费PDF全文 The effect of the different dietary carbohydrate types and levels on growth performance, haematological indices and hepatic hexokinase (HK) and glucokinase (GK) genes expression involved in control of glucose metabolism, was studied in juvenile mirror carp (Cyprinus carpio). Two carbohydrates (glucose and starch) diets with two levels (250 and 500 g kg?1) were fed to triplicate groups of 35 fish for 60 days. The best weight gain rate and specific growth rate were observed in fish fed with 250 g kg?1 glucose diet and 500 g kg?1 starch diet (P < 0.05). Fish fed with 500 g kg?1 glucose showed low feed utilization, with the highest food conversion ratio and the lowest protein efficiency ratio (P < 0.05). Hepatosomatic index was significantly higher in fish fed with glucose diets and the 500 g kg?1 starch diet compared to 250 g kg?1 starch. CHOL, HDL‐C and LDL‐C were significantly highest in fish fed with 500 g kg?1 starch than all other diets (P < 0.05). Hepatic GK mRNA expression level and activity were positively related to glucose and starch levels (P < 0.05). Correlation analysis showed that hepatic glycogen concentration was increased by dietary carbohydrate content (P < 0.05). These results suggest that GK may play a major role in the postprandial glucose utilization in juvenile mirror carp. 相似文献
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