Inflammation-related changes in cyclic AMP and cyclic GMP in bovine mastitis

Cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) cocentrations in milk and plasma samples from healthy and mastitic cows were determined by radioi-immunoassay and compared with prostaglandins (PGE2, PGF2 and thromboxane B2 [TXB2]), phospholipids and other relevant parameters in milk and blood. The concentrations of cAMP were about five times higher in plasma (p<0.01) than in milk, whereas the cGMP concentration in milk was three times higher (p<0.01) than that in plasma in both healthy and diseased animals. In mastitic milk, the cAMP and cGMP concentrations were 19% and 65% and in blood plasma 13% and 84% higher respectively than in healthy animals. In milk, cyclic nucleotide concentrations correlated with the markedly elevated cell count and also with the prostaglandin concentration and pH. In blood, cAMP correlated positively with phospholipids and cGMP with reduced glutathione (GSH). These changes are considered to be important in the disease process and, in particular, the increase in cGMP deserves further study.     

冻结和冻藏对中华绒螯蟹蟹肉品质的影响

为了研究冻结和冻藏对中华绒螯蟹蟹肉品质的影响,本研究对冻结和冻藏中华绒螯蟹的蛋白质特性、游离氨基酸、核苷酸关联成分、Ca2+-ATPase活性以及解冻汁液流失率进行了全面的评价。中华绒螯蟹较耐冻结但不耐冻藏,冻藏2周后蟹肉弹性程度开始下降。中华绒螯蟹在冻藏过程中,蟹肉中游离氨基酸、呈味核苷酸、Ca2+-ATPase活性以及解冻汁液流失率都发生明显变化。冻藏12周后相对于新鲜蟹,游离氨基酸、呈味核苷酸、Ca2+-ATPase活性以及解冻汁液流失率分别下降了25.3%、100%、41.6%和增加了9.2%。普通冻藏(-20℃)条件下,中华绒螯蟹蟹肉发生快速蛋白质分解和ATP降解,表现为游离氨基酸成分与ATP关联物成分都发生很大变化,蛋白质变性显著、汁液流失现象严重等。推测中华绒螯蟹蟹肉不耐冻藏可能与其自身的自溶酶和ATP酶类有关。     

Immunostimulant effects of nucleotide isolated from yeast RNA on carp, Cyprinus carpio L.

Nucleotides from yeast RNA were evaluated for their ability to enhance the non-specific immune responses in carp, Cyprinus carpio . Oral administration of nucleotides to fish daily for 3 days resulted in enhanced responses of phagocytic and nitroblue tetrazolium (NBT) activities in kidney phagocytic cells. This activation of kidney cells was observed for at least 10 days post-treatment. The serum complement and lysozyme activities also increased in fish treated with nucleotides. Furthermore, the number of Aeromonas hydrophila in nucleotide-treated fish significantly decreased in the blood, kidney and liver after intraperitoneal injection. Thus yeast nucleotides appear to enhance non-specific immune responses in fish.     

乳中环核苷酸提取方法研究

根据环核苷酸理化性质及乳的特点，采用酶法从乳汁中提取环核苷酸。研究表明，该方法条件温和、工艺合理、操作方便。经放射免疫测定提取浓缩液浓度为ｃＡＭＰ２０μｍｏｌ·Ｌ－１，ｃＧＭＰ０．２μｍｏｌ·Ｌ－１．     

尼罗罗非鱼制作传统上海熏鱼过程中的风味变化

为探究上海熏鱼制作过程中不同加工阶段风味物质的变化,本研究以尼罗罗非鱼肉为对象,通过高效液相色谱法、氨基酸自动分析法和固相微萃取—气相色谱—质谱联用技术对上海熏鱼4个加工阶段(生鲜罗非鱼、一次浸渍、一次浸渍后油爆和上海熏鱼成品)的风味物质进行分析和鉴定。结果显示,各阶段IMP含量呈逐渐上升趋势,是主要的鲜味核苷酸。游离氨基酸总量和呈味氨基酸含量也逐渐升高,并呈显著性差异,其中天冬氨酸和谷氨酸对上海熏鱼风味影响最大。生鲜罗非鱼、一次浸渍、一次浸渍后油爆和上海熏鱼成品中挥发性物质依次为50、84、78和82种,主要由醛类、酮类、醇类和烃类构成。因此,浸渍和油爆是上海熏鱼风味形成的主要原因,使得罗非鱼鱼体的腥味得以有效改善。     

Dietary nucleotides enhance growth performance,feed efficiency and intestinal functional topography in European Seabass (Dicentrarchus labrax)

Nucleotides, nucleosides and nucleic acids (NU) have many critical functions in supporting life and increasing evidence suggests that exogenous supply can benefit the health of mammals and fish. For these reasons, a 6‐week feeding trial was conducted on juvenile European seabass (Dicentrarchus labrax) with diets containing 0%, 0.15% and 0.3% inclusion of a NU mixture (Laltide^®) derived from the yeast Saccharomyces cerevisiae. At the end of the study no significant differences were found in fish performance, although a tendency towards better performance was indicated in fish fed the Nu0.3 diet. In relation to histological assessment, a significantly greater perimeter ratio; internal to outer (IP/OP) was observed in the posterior intestine of fish fed supplemental NU. Microvilli heights in the posterior intestine were also shown to be significantly promoted in fish fed NU diets (p < 0.05). Goblet cell abundance was shown to be unaffected by the inclusion of NU in the diet (p > 0.05). Overall, this study indicates that orally administered NU may be effective promoters of gut functional topography with marginal associated improvements to fish performance. Nonetheless, longer exposure and/or commercial scale application, and in diets that were challenging in use of high inclusion levels of plant by‐products would potentially amplify improvements in production characteristics, in turn benefiting fish culturists.     

核苷酸对动物摄食、生长与免疫功能的影响

饲料中的核苷酸对动物生长发育和免疫功能等具有重要作用。核苷酸作为一种无毒无害无残留的新型饲料添加剂,在动物营养方面有很大的发展前途。近年来国内外学者对核苷酸的研究逐渐增多。本文从促生长、诱食和改善免疫功能等方面对核苷酸在动物营养方面的应用做一综述。     

Effects of dietary nucleotides on growth,survival and metabolic response in whiteleg shrimp,Litopenaeus vannamei against ammonia stress condition

This trial was conducted to evaluate the effects of nucleotides on growth of whiteleg shrimp, Litopenaeus vannamei, and the survival and metabolic responses to ammonia stress test. Experimental diets were as follows: low fish meal diet (LFMD), and four LFMD test diets, each supplemented with 0.1% guanosine monophosphate (GMP), 0.1% inosine monophosphate (IMP), 0.1% mixture of GMP and IMP and 0.1% mixture of GMP, IMP, uridine monophosphate (UMP) and cytidine monophosphate (CMP). The shrimp specimens (initial body weight: 0.99 ± 0.01 g) were randomly allocated into five groups and fed four times daily for 8‐weeks. After the trial, final body weight was recorded and haemolymph was withdrawn for haematological analysis. The shrimp was then challenged with 70 mg/L ammonia (LC50) for 10 days. Survival and haemolymph of the shrimp were taken after exposure to ammonia. The highest growth performance was observed in the shrimp fed diet supplemented with GMP (p < .05), while survival was not influenced by the test diets in the feeding trial. In the ammonia challenge test, the highest survival was observed in the shrimp fed GMP supplemented diet compared to others. The plasma protein, glucose and cholesterol levels increased in all the treatments while triglycerides level decreased post challenge. Cortisol level recovered at day 10th after the challenge. Shrimps fed with nucleotides diets showed higher protein and glucose level compared to control groups post challenge. In general, nucleotides supplemented in the diet enhanced growth, improved stress resistance while modulating the haemolymph metabolites in L. vannamei under ammonia stress.     

Dietary nucleotides improve the growth performance,antioxidative capacity and intestinal morphology of turbot (Scophthalmus maximus)

A growth trial was conducted to evaluate the effects and safety of nucleotides in low fish meal diets on the growth performance, antioxidative capacity and intestinal morphology of turbot (Scophthalmus maximus). High fish meal control diet was formulated with 500 g kg^?1 fish meal. Seven levels (0.075, 0.15, 0.225, 0.300, 1.5 and 3.0 g kg^?1, respectively) of nucleotides were added to a low fish meal basal diet, which was formulated with 400 g kg^?1 fish meal. The eight experimental diets were fed to groups of juvenile turbot (initial weight: 6.0 ± 0.03 g) for 60 days. Results showed that compared with high fish meal control diet, low fish meal basal diet treatment had lower total antioxidative capacity (T‐AOC), glutathione peroxidase activity, fold height of proximal and distal intestine, enterocyte height of all evaluated enteric section and microvillus height of mid‐intestine and distal intestine (P < 0.05). However, supplemented nucleotides in diets could significantly improve growth (specific growth rate, SGR), feed utilization, antioxidative capacity and intestinal morphology of turbot (P < 0.05). Broken‐line regression analysis of SGR and T‐AOC showed that the optimal supplemental levels of dietary nucleotide for juvenile turbot were 0.366 and 0.188 g kg^?1, respectively. In summary, 0.300 g kg^?1 of dietary nucleotides was helpful in improving growth, feed utilization, antioxidative capacity and intestinal morphology of turbot fed with low fish meal diet. Excessive dietary nucleotides (3.0 g kg^?1) might cause oxidative stress and morphological damage in intestine and then reduce the growth of turbot.     

核苷酸对大黄鱼生长性能、肠道形态和抗氧化能力的影响

为探究饲料中添加核苷酸对大黄鱼生长性能、肠道形态和抗氧化能力的影响,实验选取初始体质量为(7.71±0.02)g的大黄鱼幼鱼为研究对象,设置2个对照组,即高鱼粉对照组FM(鱼粉含量为45.0%)和低鱼粉对照组N0(鱼粉含量为31.5%),在低鱼粉对照组基础上分别添加0、75、150、300、600和1 000 mg/kg的核苷酸,共配制出7种等氮等脂饲料,在海水浮式网箱中进行为期63 d的养殖实验。结果表明:饲料中添加核苷酸对大黄鱼的存活率、饲料效率、摄食率、鱼体组成和形体指标没有显著影响(P0.05);但增重率随着核苷酸添加量的增加呈先升高后下降趋势,在添加量为300~600 mg/kg时显著高于其他处理组(P0.05)。随着核苷酸添加量的增加,血清中超氧化物歧化酶(SOD)和总抗氧化力(T-AOC)的活力呈先升高后下降的趋势,并在300 mg/kg时显著高于低鱼粉对照组(P0.05)。核苷酸对大黄鱼肠道肌肉层厚度和微绒毛高度有显著影响(P0.05),分别在添加量为150和300mg/kg时出现最大值;而对肠道褶皱高度无显著影响(P0.05)。结果表明,饲料中添加核苷酸能促进大黄鱼生长,改善肠道形态结构和增强机体的抗氧化能力。以增重率为指标,利用折线模型计算得到大黄鱼幼鱼饲料中核苷酸的适宜添加量为194.91 mg/kg。