Metabolism of exogenous histamine in rainbow trout (Oncorhynchus mykiss)

Information on the metabolism of exogenous histamine in fish is of much concern regarding the effect of dietary histamine on fish. Histamine catabolic enzymes, diamine oxidase and histamine N-methyl transferase were measured in the tissues of rainbow trout. Diamine oxidase was detected in the stomach, pylorus caeca and intestine. Histamine N-methyl transferase was detected only in the liver.A change in the contents of histamine and its metabolites was observed in the tissues of rainbow trout after oral administration of histamine. A large amount of imidazole acetic acid was observed in the serum, kidney, liver and muscle. On the other hand, 1-methyl histamine was detected only in the liver. Histamine and its metabolites, imidazole acetic acid and 1-methyl histamine were metabolized and diminished within 48 hr in all tissues.These results showed that histamine was metabolized by two metabolic routes in rainbow trout. One is the main pathway producing imidazole acetic acid by intestinal diamine oxidase and the other is the complementary pathway producing 1-methyl histamine by liver N-methyl-transferase.     

The glutathione S-transferases of fish

Substantial soluble glutathione S-transferase activity and millimolar reduced glutathione (GSH) are present in most tissues of both teleosts and elasmobranchs. The hepatic enzymes of fish conjugate a range of electrophilic substrates with GSH, although their specificities are less broad than those of the transferases in rodent liver. There is no good evidence that fish transferases have ligandin-like activity or a suicide function. All fish livers tested have several transferase isoenzymes. They are dimers of subunits whose M_rs are about 25 kDa and which may have different catalytic properties. In some species transferase activity is induced by agents such as phenols or 3-methylcholanthrene. Glutathione S-transferases are important detoxication enzymes in fish.     

基于全基因组和转录组的绿豆谷胱甘肽转移酶基因及其对镉胁迫的响应

以绿豆为材料,运用生物信息学、转录组学和酶学等分析方法,对绿豆GST家族基因结构及其表达蛋白的特征进行分析,并检测镉（Cd）胁迫下GST基因表达谱和酶活性变化。结果表明,绿豆基因组中包含有93个GST基因,分为Tau、Phi、Lambda、Theta、Zeta、DHAR、EF1Bg、GHRs、mPGES2和TCHQD等10类,以Phi和Tau类基因数最多;不同类基因结构存在较大差异,Tau类和TCHQD类含有2个外显子,Phi类和GHRs类分别含3和5个外显子,其余基因外显子数目在6~10个。其中只有40个基因在绿豆中表达,31个基因在根、茎、叶中都有表达,6个基因选择性表达。Cd胁迫上调大多数基因的表达量,根、茎、叶中被显著上调的GST基因分别为10、8和4个,平均上调倍数为2.17、2.25和3.26;Cd胁迫显著升高根和茎中GST酶活分别达2.14和1.27倍,与基因表达量的变化一致。表明绿豆根中GST基因及其酶活在Cd胁迫响应中起最主要作用。研究结果为植物GST基因的进一步研究和在植物抗逆中生物技术应用提供了科学资料。     

Biochemical response in rats to the addition of curry leaf (Murraya koenigii) and mustard seeds (Brassica juncea) to the diet

Three groups with 12 weanling male albino rats were group fed for 90 days on a standard laboratory rat diet plus 20% coconut oil either without a supplement or with the addition of 10% curry leaf or 10% mustard seeds. Feed was offered at a level of 10% body weight. At the end of the trial, measurements were made on the total serum cholesterol, high density lipoproteins, low density lipoproteins, and very low density lipoproteins fractions, release of lipoproteins into the circulation, lecithin cholesterol acyl transferase activity and lipoprotein lipase activity. Feed intake and mean body weight of the rats on each treatment was not significantly different. Both spices resulted in a reduction in total serum cholesterol and LDL+VLDL, an increase in the HDL, lower release of lipoproteins into the circulation and an increase in the LCAT activity.     

Does sward height grazed by ewes in mid- to late-pregnancy affect indices of colostrum intake by twin and triplet lambs?

AIMS: To determine if sward height grazed by ewes in mid- to late-pregnancy affects subsequent indices of colostrum intake by twin and triplet lambs, and the extent of the variation in colostrum intake between twin and triplet litter-mates.

METHODS: Blood samples were collected from 75 twin and 46 triplet litters, respectively, 24–36 h after birth. Samples were not collected from lambs that died before this age. Lambs were born to ewes which had grazed one of four sward heights (2, 4, 6 and 8 cm) during mid- to late-pregnancy. Serum samples were analysed for gamma-glutamyl transferase (GGT) activities and glucose concentrations. The number of lambs present at weaning was used to determine lamb survival rate.

RESULTS: GGT activities of lambs born to ewes that grazed swards 2 cm high were lower than those born to ewes that grazed swards 4 and 6 cm high (p=0.053 and p=0.037, respectively). Glucose concentrations were higher in twin than triplet lambs (p=0.003) and in lambs born to ewes grazed on swards 6 cm high than those born to ewes grazed on swards 2 cm high (p=0.033). These differences were not evident after correction for differences in birthweight. There was significant (p<0.001) variation within litter-mates for GGT activities and glucose concentrations in both twins and triplets. The blood constituent status of lambs that died before the 24–36 h collection period is not known. However, lambs which died after this period had significantly lower GGT activities (p=0.009) and glucose (p=0.010) concentrations at the time of sampling than those which survived.

CONCLUSIONS: Farmers should ensure twin- and tripletbearing ewes in mid- to late-pregnancy are grazing at least 4 cm of herbage to ensure colostrum intake of lambs in the postpartum period is not adversely affected.     

A review of diagnostic tests for diagnosing failure of transfer of passive immunity in dairy calves in New Zealand

ABSTRACT

The aim of this review is to critically assess the test characteristics and practicality of published data on direct and indirect tests for diagnosing failure of transfer of passive immunity (FPT) in dairy calves in New Zealand, to provide recommendations for veterinary practitioners, and to examine the recommended sample size for assessing herd-level prevalence of FPT and the confidence in the results obtained. The definition of FPT is based on measurement of concentrations of IgG in serum of neonatal calves after colostrum intake. The gold standard method for measurement of concentrations of IgG is radial immunodiffusion. However its cost, requirements for laboratory equipment, and the time taken to obtain results have meant that alternative tests have been developed. The turbidimetric immunoassay and ELISA also directly measure concentrations of IgG. Indirect tests include measurement of concentrations of total proteins (TP) in the laboratory or using a refractometer, γ-glutamyl transferase (GGT) activity, and the zinc sulfate turbidity (ZST) test. Of the indirect tests, measurement of concentrations of TP in the laboratory or using a refractometer combine high specificity and sensitivity with a consistent association with concentrations of IgG in calves between 1–7 days of age. Using a refractometer is less accurate than direct measurement in a laboratory, but is still a suitable test if low cost and speed are important. Although GGT activity is strongly associated with concentrations of IgG in serum, the relationship varies with time after birth. Therefore the target thresholds change with time, increasing error compared to the measurement of concentrations of TP in serum. Similarly, factors other than total concentrations of IgG have a significant effect on the association with ZST test, complicating interpretation. Thus, when direct measurement of concentrations of IgG is not feasible, the recommendation is that concentrations of TP in serum should be used as the diagnostic test for diagnosis of FPT, providing calves are not dehydrated. Using a sample size of 12 calves is suitable for estimating whether the herd-level prevalence of FPT is <20% or >20%, if there are no calves or >5 calves diagnosed with FPT, respectively, but is limited in diagnostic confidence when 1–4 calves test positive. Diagnostic interpretation can be significantly improved if tests of FPT are used alongside information on the likely risk of FPT on the tested farm.     

Molecular approaches for enhancing sweetness in fruits and vegetables

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.     

DGAT基因在畜禽育种中的应用

DGAT是一种甘油酰基转移酶(Diacylgycerol Acyltransferase,DGAT),该酶与脂肪代谢、脂类在组织中的沉积有很大关系,它的主要作用机制是使二酰甘油加上脂肪酸酰基形成三酰甘油。编码该酶的基因有DGAT1和DGAT2,前者属于ACAT基因家族,后者属于DGAT2基因超家族。综述了DGAT基因定位、结构、生物学效应及在畜禽育种上的应用,并对DGAT基因在畜禽育种中的应用前景进行了探讨。     

肉碱棕榈酰转移酶基因在绵羊和山羊不同肌肉组织中的表达分析

采用实时荧光定量PCR方法比较分析了肉碱棕榈酰转移酶(carnitine palmitoyl transferase,CPT)基因在绵羊和山羊不同组织中的表达差异。研究结果表明,CPT1A mRNA在绵羊肝脏、脾脏中表达明显高于CPT1B、CPT2,CPT1B mRNA在绵羊腹外斜肌中的表达明显高于CPT1A、CPT2。CPT1A mRNA在山羊脾脏中表达明显高于CPT1B、CPT2 mRNA在山羊脾脏中的表达,CPT1B mRNA在山羊后腿股二头肌、腹外斜肌中的表达明显高于CPT1A、CPT2 mRNA在山羊后腿股二头肌中的表达。CPT1A mRNA在绵羊肝脏中的表达显著高于山羊中CPT1A mRNA的表达(P＜0.05)。CPT1A、CPT1B、CPT2基因在绵羊心脏、脾脏、腰大肌中的表达显著高于在山羊中的表达(P＜0.05),CPT1A、CPT1B、CPT2基因在山羊后腿股二头肌中的表达显著高于在绵羊中的表达(P＜0.05)。CPT1A、CPT1B、CPT2基因在绵羊、山羊各组织中的表达存在差异,可能与各基因表达模式、肌肉组织纤维类型、脂肪沉积含量不同等因素有关。     

PRDM家族蛋白结构与功能研究进展

PRDM家族蛋白是具有一个PR结构域和数量不等锌指结构(除了PRDM11),广泛存在于灵长类、啮齿动物、鸟类和两栖动物中能够调控表观遗传的蛋白。部分PRDM蛋白家族成员的PR结构域具有组蛋白赖氨酸转移酶活性(HMT),影响表观遗传,PRDM蛋白锌指结构具有DNA、RNA、蛋白识别结合能力;另一部分PRDM家族成员虽然具有PR结构域,但不具有HMT活性,在癌症发生、原始生殖细胞特化、神经系统发育、造血、血管发展、胚胎发育中发挥重要作用。PRDM家族蛋白通过甲基转移或募集染色体结构重塑复合物,调控基因表达和修改染色体结构,在细胞特化和疾病调控中起到重要作用。论文综述了PRDM家族蛋白结构与功能最新研究进展。