水产动物苯丙氨酸研究进展

苯丙氨酸(Phe)是鱼类不能靠自身代谢合成的几种必需氨基酸之一,属芳香族氨基酸。Phe的营养和生理活性已被广泛应用于畜牧、医药和食品等领域,但Phe在水产动物中的生理活性机制尚不明晰。本文对Phe的合成与代谢、水产动物需求量及其在水产养殖中的应用作一综述,为全面了解各类水产动物对Phe的营养需求、代谢机制提供参考。     

于桥水库重要经济鱼类肌肉营养价值评定

对于桥水库8种重要经济鱼类营养价值进行分析评价.采样氨基酸自动分析仪和凯氏自动定氮仪对肌肉进行成分分析.结果表明:8种鱼样品均检测出17种氨基酸,必需氨基酸的含量及其占氨基酸总量的比例都高于联合国粮食及农业组织/世界卫生组织(FAO/WHO)提出的标准.根据氨基酸评分(AAS),8种鱼类的第一限制性氨基酸为甲硫氨酸和胱氨酸,第二限制性氨基酸为苏氨酸;而根据化学评分(CS),其第一限制性氨基酸为甲硫氨酸和胱氨酸,第二限制性氨基酸为苯丙氨酸+酪氨酸.于桥水库出产的鱼类是营养全面的优质蛋白源,是人类理想的动物食品.     

冷水性鱼类对蛋白质与氨基酸的营养需求

阐述冷水性鱼类(鲑鳟鱼类)对蛋白质与氨基酸的营养需求,即蛋白质的生理功能、蛋白质在冷水性鱼类体内的消化利用过程、冷水性鱼类对蛋白的营养需求、冷水性鱼类对氨基酸的营养需求、冷水性鱼类必需氨基酸营养缺乏症、氨基酸间的相互关系。     

鱼类维生素营养研究概况

文章概述了国内外鱼类维生素营养的研究情况,并提供了鱼类维生素需要量和供给量的推荐值,以期对鱼类维生素营养研究起到一定的引导作用。     

磷在鱼类营养中应用的研究进展

磷是鱼类营养中的研究重点之一.本文综述了近年来磷在鱼类营养中的研究进展,为今后鱼类对磷需要的研究提供参考.     

鱼类饲料配制中的营养问题

鱼类是栖息于水中的变温动物,它们与陆生的畜禽比较,虽然物质代谢的原理相同,但鱼类的消化器官及其机能、对饲料的要求和营养需要等方面却与畜禽有很大差异。为了充分发挥鱼类的生产潜力,在鱼类饲料配制中必须注意其营养需要的特点,现简要分述于下。1 能量和蛋白能量比 鱼类生长发育,首先需要能量,饲料能量是鱼类营养中最基本的营养需求,是鱼类饲料     

锌调节鱼类脂肪代谢的研究进展

锌是鱼类必需的微量元素,具有维持鱼类正常生长、发育和营养代谢等功能。饲料中锌缺乏或锌过量均对水产动物的生长、发育和营养代谢等产生负面影响。因此,文章概述了锌在鱼体内的代谢过程,总结了目前锌调控鱼类脂肪代谢的分子机制,展望了锌在鱼类营养代谢方面的研究方向,为加强氨基酸螯合锌等新型饲料添加剂开发、推进鱼类营养代谢的分子机制的探索提供参考。     

鱼类的生长模型及其在营养需求研究中的应用

<正>以统计分析方法对鱼类的生长、营养需求进行研究并建立生长模型,可以得到更准确、更科学的数据。通过对鱼类生长模型的分析研究,不仅可以动态地了解鱼类的生长过程,预测鱼类的生长规律,而且在鱼类营养需求研究中的应用也非常广泛。     

鲷科鱼类蛋白质和氨基酸营养需求研究进展

鲷科（Sparidae）鱼类为世界性主要海水养殖鱼类品种之一。近年来，鲷科鱼类在我国养殖规模逐年扩增，对营养全面的专用配合饲料需求日益增加。尽管国内外对金头鲷（Sparus aurata）、黑鲷（Acanthopagrus schlegelii）和真鲷（Pagrus major）等品种已经进行了较为全面的营养研究，但对其他品种（如黄鳍鲷，Acanthopagrus latus）尚未进行系统研究。考虑到几种鲷科鱼类在分类地位和生活习性有一定相似之处，因此很有必要对鲷科鱼类营养研究进行系统整理和比较。文章就国内外对鲷科鱼类的蛋白质和氨基酸营养研究进行综述，以期为鲷科新品种鱼类营养生理研究及专用饲料研发提供科学参考。     

鱼类脂类代谢调控机制

<正>近年来关于鱼类脂类营养研究较多,但鱼类脂类代谢机制方面还缺少相应的资料。如何满足鱼类脂肪营养需求,不仅节省蛋白质和多不饱和脂肪酸,而且可以最大限度的利用廉价脂肪酸,这方面的内容会直接影响鱼类代谢和饲料质量。因此,了解和掌握鱼类脂肪代谢规律,对于研究鱼类营养非常重要。     

苯丙氨酸缺乏幼建鲤的病理组织学观察及抗氧化能力变化

本试验旨在研究苯丙氨酸缺乏对幼建鲤组织器官病理变化和抗氧化能力的影响。将平均体重为(7.53±0.01)g的幼建鲤随机分为2组(每组4个重复,每个重复50尾鱼),分别饲喂苯丙氨酸含量为1.9(缺乏组)和10.9 g/kg(对照组)的试验饲料60 d。结果表明:苯丙氨酸缺乏引起幼建鲤尾鳍向上弯曲;肠上皮细胞坏死、脱落,肠黏膜固有层水肿;肝细胞空泡变性;胰腺细胞肿胀,胰腺腺泡中酶原颗粒减少;脾脏含铁血红素沉积;肌纤维肌浆凝固,部分肌浆溶解或肌纤维断裂;后肾肾小球充血、肿大,管腔轻度变形;鳃小片毛细血管扩张充血,严重者鳃小片溶解、脱落,软骨消失;脂质过氧化和蛋白质氧化增加,血清抗氧化酶活性、谷胱甘肽含量以及自由基清除能力降低。由此得出,苯丙氨酸缺乏会造成幼建鲤组织器官不同程度的病理损伤以及抗氧化能力的降低。     

Purification and partial characterization of a cadmium-binding protein from the liver of rainbow trout (Onchorynchus mykiss).

This study describes the isolation and partial characterization of a low molecular weight (approximately 14 kDa), cadmium-binding protein from rainbow trout (Onchorynchus mykiss) liver. Rainbow trout were injected intraperitoneally with 3.5 mg/kg cadmium chloride (total body dose) twice weekly for 3 wk. Livers were removed and a cadmium-binding protein was isolated. Monoclonal antibodies produced against this protein were used in the affinity purification process. Amino acid analysis showed the protein contained 3.8 mol% cysteine, 3.5 mol% phenylalanine, 2.2 mol% tyrosine and 1.9 mol% histidine. The low cysteine content suggests that it was distinct from metallothionein. The monoclonal antibodies were also used to identify the protein in liver homogenates from both cadmium-exposed and control fish and in the testes of cadmium-exposed mice lacking the gene for both metallothionein-1 and metallothionein-II. The compound identified in this study represents a non-metallothionein cadmium-binding protein that appears to be highly conserved.     

Isolation of mannose-binding C-type lectin from sea lamprey (Petromyzon marinus) plasma and binding to Aeromonas salmonicida

The sea lamprey (Petromyzon marinus) is a parasitic cartilaginous fish of the North American Great Lakes and a predator of many bony fish species of commercial importance to the fishing industry. Mannose-binding C-type lectin (MBL) was isolated by mannan-agarose affinity chromatography from sea lamprey plasma. Mannose-binding lectin has not before been identified and quantitated in the plasma of this sea lamprey species. The affinity-purified and 2-ME reduced lamprey MBL showed two bands of 35kDa and 65kDa by SDS-PAGE and Western blotting using guinea pig anti-MBL IgG as the primary antibody. Amino acid composition analysis (mol%) of the purified lamprey MBL found high amounts of histidine, threonine, tyrosine and phenylalanine present when compared with three other vertebrate MBLs. N-terminal amino acid sequencing by Edman degradation for the first 10 residues gave XXXTKGCPDA. Lamprey plasma contained 261mug of MBL/ml of plasma. Plasma protein concentration was 40.1mg/ml. Lamprey MBL was present then in plasma at 6.5mug MBL/mg total protein. The sea lamprey MBL also specifically binds to mannose on the surface of the pathogen Aeromonas salmonicida. The presence of MBL in high concentration in lamprey plasma could be important in their innate immunity and resistance to infection. This study describes the presence of MBL in sea lamprey plasma and evidence for a C-type lectin complement pathway of innate immunity.     

Assessment of the neurologic effects of dietary deficiencies of phenylalanine and tyrosine in cats

OBJECTIVE: To determine the neurologic effects of reduced intake of phenylalanine and tyrosine in black-haired cats. ANIMALS: 53 specific pathogen-free black domestic shorthair cats. PROCEDURE: Cats were fed purified diets containing various concentrations of phenylalanine and tyrosine for < or = 9 months. Blood samples were obtained every 2 months for evaluation of serum aromatic amino acid concentrations. Cats were monitored for changes in hair color and neurologic or behavioral abnormalities. Three cats with neurologic deficits underwent clinical and electrophysiologic investigation; muscle and nerve biopsy specimens were also obtained from these cats. RESULTS: After 6 months, neurologic and behavioral abnormalities including vocalization and abnormal posture and gait were observed in cats that had received diets containing < 16 g of total aromatic amino acid/kg of diet. Electrophysiologic data and results of microscopic examination of muscle and nerve biopsy specimens from 3 cats with neurologic signs were consistent with sensory neuropathy with primary axonal degeneration. Changes in hair color were detected in cats from all groups receiving < 16 g of phenylalanine plus tyrosine/kg of diet. CONCLUSIONS AND CLINICAL RELEVANCE: Findings suggested that chronic dietary restriction of phenylalanine and tyrosine in cats may result in a predominantly sensory neuropathy. In cats, the long-term nutritional requirement for phenylalanine and tyrosine appears to be greater for normal neurologic function than that required in short-term growth experiments. Official present-day recommendations for dietary phenylalanine and tyrosine in cats may be insufficient to support normal long-term neurologic function.     

Effect of low levels of dietary tyrosine on the hair colour of cats

Experiments were conducted to investigate the basis for the change in hair colour of black cats to reddish-brown. Black cats were given purified diets based on gelatin, casein plus lactalbumin, or crystalline amino acids as protein sources. Diets that caused the colour of hair to change to reddish-brown were associated with a reduction in melanin in hair (observed by direct microscopic examination), a decreased total melanin concentration and low concentrations of tyrosine in plasma. Reddish hair coat was induced in black kittens born to queens given a tyrosine-deficient diet during pregnancy. Black hair colour was maintained or restored by diets containing a high concentration of tyrosine or phenylalanine. Current dietary recommendations for dietary tyrosine and phenylalanine for cats are below those required to support maximal melanin synthesis in black cats. The requirement appears to be greater than a combination of 4.5 g tyrosine plus 12 g phenylalanine/kg diet but less than 24 g phenylalanine alone/kg diet.     

Regulation of pancreatic exocrine secretion in goats: differential effects of short‐ and long‐term duodenal phenylalanine treatment

Four yearling goats (31.2 ± 2.5 kg), surgically fitted with common bile duct reentrant and duodenal catheter, were used in two 4 × 4 Latin square design experiments to investigate the effects of duodenal infusion of phenylalanine for different times on pancreatic exocrine secretion (PES). In experiment 1 (the long‐term experiment), goats were duodenally infused with 0, 2, 4 or 8 g/day phenylalanine for 14 day. Pancreatic juice and jugular blood samples were collected over 1‐h intervals for 6 h daily from day 11 to day 14 to encompass a 24‐h day. In experiment 2 (the short‐term experiment), goats were infused with phenylalanine for 10 h continuously at the same infusion rate as experiment 1 after feed deprivation for 24 h repeated every 10 day. Pancreatic juice and blood samples were collected at 0, 1, 2, 4, 6, 8 and 10 h of infusion. The volume and pH of pancreatic juice were measured, and a 5% subsample was composited and frozen until analysis of enzyme activities. Plasma was frozen until analysis of insulin and cholecystokinin (CCK). In experiment 1, pancreatic juice, α‐amylase secretion and plasma CCK concentration responded quadratically (p < 0.05), with the top value observed at the 2 g/day phenylalanine. Trypsin secretion had a quadratic response (p < 0.05), with secretion increasing up to 4 g/day phenylalanine and decreasing thereafter. Phenylalanine linearly decreased pancreatic protein and lipase secretion (p < 0.05). The results of correlation analysis showed significant correlations (p < 0.05) between plasma CCK concentration and secretion of α‐amylase and trypsin. However, the short‐term phenylalanine infusion did not influence (p > 0.05) pancreatic juice, protein, α‐amylase, lipase, trypsin secretion and plasma CCK concentration. These results indicate PES of ruminants is stimulated by phenylalanine and is potentially mediated by CCK in the long‐term duodenal infusion treatment, but is not influenced by phenylalanine in the short‐term duodenal infusion treatment.     

Pig blastocyst development in vitro is affected by amino acids

Pig embryos were removed 5 d after onset of estrus and cultured in modified Krebs-Ringer bicarbonate (mKRB) medium containing bovine serum albumin (BSA; 1 mg/ml). Media in Exp. 1 and 2, but not in Exp. 3, contained 10% heat-inactivated lamb serum (LS). In Exp. 1, embryos were cultured in 1) mKRB + LS or mKRB + LS supplemented with 2) glutamine (2 mM); 3) phenylalanine (.1 mM), methionine (.05 mM) and isoleucine (.2 mM); or 4) phenylalanine, methionine, isoleucine and glutamine. Embryos cultured in media with supplemental phenylalanine, methionine and isoleucine attained larger (P less than .05) volumes during culture and initiated hatching at an increased (P less than .05) frequency compared with embryos cultured without additional amino acids. In contrast, adding glutamine depressed (P less than .05) the maximum volumes observed during culture. In Exp. 2 mKRB + LS was compared with mKRB + LS plus phenylalanine (.1 mM), methionine (.05 mM) and isoleucine (.2 mM); methionine and isoleucine; phenylalanine and isoleucine, or phenylalanine and methionine. Embryos cultured in media supplemented with phenylalanine and methionine attained larger (P less than .05) volumes than embryos cultured in either media without added methionine. Fewer (P less than .05) embryos cultured without methionine initiated hatching (56%) compared with embryos provided methionine (89%). In Exp. 3, we evaluated the addition of glutamine (1 mM) with or without phenylalanine (.1 mM), methionine (.05 mM) and isoleucine (.2 mM) to serum-free mKRB. Adding glutamine alone, but not in combination, increased (P less than .05) blastocyst volumes on d 3 and maximum volume attained during culture compared with embryos cultured in mKRB alone.(ABSTRACT TRUNCATED AT 250 WORDS)     

A Preliminary Study of 13C-Phenylalanine and 13C-Dipeptide Breath Tests in Horses

This study aimed to establish a standard dose and sample collection time for ¹³C phenylalanine and ¹³C-Dipeptide breath test in horses. To evaluate dose-dependent effects, healthy horses received 2.5 mg/kg, 5 mg/kg, and 10 mg/kg ¹³C phenylalanine dissolved in 1 ml/kg distilled water and 1.25 mg/kg, 2.5 mg/kg, and 5 mg/kg ¹³C dipeptide dissolved in 2 ml/ kg distilled water. Tmax was observed during the sample collection time. For ¹³C phenylalanine, the standard deviation of Cmax at 5 mg/kg was lower than that of 10 mg/kg. For ¹³C dipeptide, the standard deviation of Tmax was the lowest at 5 mg/kg. This study revealed that an optimal dose for breath tests with ¹³C phenylalanine and ¹³C dipeptide may be 5 mg/kg in horses.     

日粮苯丙氨酸水平对0～4周龄泰和乌鸡生产性能及组织黑色素含量的影响

为研究日粮苯丙氨酸水平对泰和乌鸡生产性能和组织黑色素含量的影响。选用1日龄泰和乌鸡108只,随机分成3组,每组设3个重复,每个重复12只鸡(公母各半),饲养至4周龄。试验鸡组分别饲喂3种苯丙氨酸水平的日粮,日粮苯丙氨酸水平分别为0.73%、1.00%和1.27%。结果表明:日粮苯丙氨酸水平显著影响0~4周龄泰和乌鸡平均日增重(P<0.01),其中1.27%组日增重极显著高于0.73%组(P<0.01),显著高于1.00%组(P<0.05);1.00%组显著高于0.73%组(P<0.05)。但日粮苯丙氨酸水平对泰和乌鸡的饲料转化效率(料重比)和平均日采食量无显著影响(P>0.05)。胸肌黑色素含量随着日粮苯丙氨酸水平的提高而降低,1.27%组胸肌黑色素含量极显著低于0.73%和1.00%组(P<0.01),但0.73%和1.00%两组之间无显著差异(P>0.05)。尽管腿肌和皮肤黑色素含量在各组之间不存在显著差异(P>0.05),但黑色素含量有随日粮苯丙氨酸水平提高而增大的趋势。     

The effect of diarrhea on the oxidation of 14C-phenylalanine in piglets receiving diets varying in protein and proline concentration.

The oxidation rate of L-[1-14C]phenylalanine in piglets suffering from diarrhea and receiving diets varying in concentration of protein or proline was compared to the oxidation rates in healthy animals. Phenylalanine oxidation was used to indicate the partition of absorbed amino acids between protein synthesis and oxidation. Piglets receiving adequate protein diets and suffering from diarrhea oxidized significantly more phenylalanine (P less than 0.001) than healthy piglets. Piglets receiving additional proline and with symptoms of diarrhea oxidized phenylalanine at rates 50 to 70% higher than healthy piglets. The results show that piglets with diarrhea are less able to retain absorbed amino acids for protein synthesis than healthy pigs. The reduced nitrogen retention commonly observed in animals with diarrhea may be partly explained by the increased catabolism of absorbed amino acids.