Utilization of metabolic scope in relation to feeding and activity by individual and grouped zebrafish, Brachydanio rerio (Hamilton-Buchanan)

Metabolic scope and its utilization in relation to feeding and activity were measured in individual and grouped zebrafish (weight range, 430–551 mg) at 24° C by respirometry. Mean maximum metabolic rate, induced by swimming to exhaustion, R_max(i), was 1223 (s.d. , 157) mg O₂, kg^?1 h^?1 for individuals. Standard metabolic rate, R_s. was 364 mg O₂ kg^?1 h^?1, as estimated by extrapolating to zero activity from measurements of unfed, spontaneously active individuals. Mean routine metabolic rate, R_rout, of individuals was 421 (s.d. , 58) mg O₂, kg_-1 h_-1. The mean voluntary maximum metabolic rate, R_max(v), following transfer of minimally exercised fish to the respirometer, was 1110 (s.d. , 83) mg O₂ kg ^?1 h^?1 for groups of six fish, and was not significantly different from the value measured for individuals, 1066 (s.d. , 122) mg O₂, kg^?1 h^?1. Grouped fish acclimated to the respirometer more slowly than individual fish and exhibited significantly higher R_rout, apparently a result of greater social interaction and activity in groups. Mean R_rout for groups was 560 (s.d. , 78) mg O₂, kg^?1 h^?1. While groups of zebrafish fed a ration of 5% wet body weight day^?1 exhibited consistently higher metabolic rates than fish fed rations of 2.5% wet body weight day^?1 the high ration group still used only a maximum of 77% of the metabolic scope. Zebrafish of the size studied do not appear to demonstrate a high degree of conflict in utilization of metabolic scope by different respiratory components. The metabolic rates measured for zebrafish are among the highest yet measured for fish of similar size and at similar temperatures.     

Biosynthesis of the anti‐diabetic metabolite montbretin A: glucosylation of the central intermediate mini‐MbA

Type 2 diabetes (T2D) affects over 320 million people worldwide. Healthy lifestyles, improved drugs and effective nutraceuticals are different components of a response against the growing T2D epidemic. The specialized metabolite montbretin A (MbA) is being developed for treatment of T2D and obesity due to its unique pharmacological activity as a highly effective and selective inhibitor of the human pancreatic α‐amylase. MbA is an acylated flavonol glycoside found in small amounts in montbretia (Crocosmia × crocosmiiflora) corms. MbA cannot be obtained in sufficient quantities for drug development from its natural source or by chemical synthesis. To overcome these limitations through metabolic engineering, we are investigating the genes and enzymes of MbA biosynthesis. We previously reported the first three steps of MbA biosynthesis from myricetin to myricetin 3‐O‐(6′‐O‐caffeoyl)‐glucosyl rhamnoside (mini‐MbA). Here, we describe the sequence of reactions from mini‐MbA to MbA, and the discovery and characterization of the gene and enzyme responsible for the glucosylation of mini‐MbA. The UDP‐dependent glucosyltransferase CcUGT3 (UGT703E1) catalyzes the 1,2‐glucosylation of mini‐MbA to produce myricetin 3‐O‐(glucosyl‐6′‐O‐caffeoyl)‐glucosyl rhamnoside. Co‐expression of CcUGT3 with genes for myricetin and mini‐MbA biosynthesis in Nicotiana benthamiana validated its biological function and expanded the set of genes available for metabolic engineering of MbA.     

Examination of lymphokines induced in mice following immunization with recombinant simian virus 40 large tumor antigen

Baculovirus-derived recombinant simian virus 40 (SV40) large tumor antigen (T-Ag) was used to immunize BALB/c mice to examine the lymphokines produced following immunization. Specifically, we examined production of interleukin-2 (IL-2), IL-4, IL-5 and interferon (IFN) from immune lymphocytes cultured with decreasing concentrations of recombinant SV40 T-Ag. We identified elevated levels of IFN and IL-2 by enzyme-linked immunosorbent assay and a murine CTLL-2 proliferation biossay respectively. We were unable to detect either IL-4 or IL-5. These data indicate the previously reported tumor immunity induced by recombinant SV40 T-Ag immunization most likely reflects a TH1-like immune response based on thein vitro production of both IFN and IL-2 by immune lymphocytes.     

Regulatory and molecular properties of citrate synthases from methylotrophs

Abstract Gram-negative methylotrophs contain a high- M _r'large' citrate synthase. Gram-positive methylotrophs, on the other hand, contain a 'small' citrate synthase. These differences in M _r coincided partly with differences in NADH sensitivity. Citrate synthases from obligate Gram-negative and Gram-positive facultative methylotrophs were insensitive to feedback inhibition by NADH; only the enzymes from Gram-negative facultative methylotrophs were inhibited by NADH.     

Genetic metabolic polymorphisms and the risk of cancer: a review of the literature

The purpose of this paper is to systematically analyse the design and results of epidemiological studies on the association between various types of cancer (lung, bladder, breast, colon, stomach) and four genetically-based metabolic polymorphisms, involved in the metabolism of several carcinogens (glutathione-S-transferase M1, debrisoquine hydroxylase, N acetyltransferase, aryl hydrocarbon hydroxylase). These inherited polymorphisms usually cause modifications in the quality or quantity of the relevant enzymes. Such enzymes are involved in the activation/inactivation of known carcinogens and seem to modify the extent to which carcinogens interact with DNA in target tissues. Two enzymes, debrisoquine hydroxylase and aryl hydrocarbon hydroxylase, activate procarcinogens to carcinogens (phase I enzymes). The other two, glutathione-S-transferase M1 and N-acetyltransferase, mainly detoxity carcinogenic substances (phase II enzymes). Because of their role as host factors (modulating the action of carcinogens), it has been hypothesized that subjects presenting a specific phenotype for such polymorphisms could be at a greater risk of developing various types of cancer. A number of epidemiological studies have investigated such associations, often with discordant results. We examine and discuss the design of the studies, and present a meta-analysis of the available data.     

Two tumor models of curative adoptive chemoimmunotherapy using tumor-infiltrated spleen cells with potent antitumor cytotoxicity stimulated by antigen-sharing tumors

Previously we have established curative protocols for adoptive chemoimmunotherapy (ACIT) of mice bearing different plasmacytomas that are known to bear cross-reacting antigens: (a) the cure of mice bearing an early-stage, nonpalpable MOPC-315 tumor by a very low dose of cyclophosphamide (10 mg/kg) and cultured MOPC-315-tumor-infiltrated (TI) spleen cells (25×10⁶) and (b) the cure of mice bearing a late-stage, relatively drug-resistant, highly metastatic RPC-5 tumor with cyclophosphamide (100 mg/kg) and cultured RPC-5 TI spleen cells (25×10⁶–50×10⁶). In both models, the spleen cells were obtained from mice bearing a late-stage tumor and were cultured for 5 days in the presence of polyethyleneglycol 6000 and autochthonous tumor cells as a source of tumor antigen. Here we show that RPC-5 tumor cells could substitute for MOPC-315 tumor cells in the 5-day culture of MOPC-315 TI spleen cells so that they became curative in ACIT for mice bearing an early-stage MOPC-315 tumor. Similarly, MOPC-315 tumor cells could substitute for RPC-5 tumor cells in the 5-day culture of RPC-5 TI spleen cells so that they became curative in ACIT of mice bearing a late-stage RPC-5 tumor. In addition, RPC-5 TI spleen cells cultured with either MOPC-315 or RPC-5 tumor cells were effective in curing all mice bearing an early-stage MOPC-315 tumor by ACIT. However, MOPC-315 TI spleen cells whether cultured with MOPC-315 or RPC-5 tumor cells, were much less effective than cultured RPC-5 TI spleen cells in curing mice bearing a late-stage RPC-5 tumor by ACIT (although the survival of these mice was extended significantly). Interestingly, whereas RPC-5 TI spleen cells cultured with either MOPC-315 or RPC-5 tumor cells were as effective as MOPC-315 TI spleen cells cultured under the same conditions in lysing MOPC-315 tumor cells in vitro, MOPC-315 TI spleen cells that had been cultured with either MOPC-315 or RPC-5 tumor cells exerted a much weaker in vitro cytotoxic T lymphocyte activity against RPC-5 tumor cells than did RPC-5 TI spleen cells that had been cultured under the same conditions.Work was supported by research grant CA-30088 from the National Cancer Institute and IM-435 from the American Cancer Society. M. B. M. was supported by Career Development Award CA-01350 from the National Cancer InstituteThis work is in partial fulfillment of the requirements for the Ph. D. degree     

蛋白质O-GlcNAc修饰的检测技术

O-连接的N-乙酰葡糖胺（O-GlcNAc）修饰是位于细胞浆和细胞核蛋白质的丝氨酸或苏氨酸上的一种翻译后修饰,在高等真核生物细胞中广泛存在.越来越多的研究表明,O-GlcNAc修饰在代谢调控、压力应激、细胞周期、凋亡、糖尿病、心血管疾病和癌症等多种生理和病理过程中发挥重要作用,因此, O-GlcNAc修饰已受到众多生命科学领域研究人员的关注.然而,由于O-GlcNAc修饰与传统的N聚糖和O聚糖修饰有所不同,常规糖基化修饰的检测方法并不适用于O-GlcNAc.本文对O-GlcNAc修饰的检测及其修饰位点的确定方法进行了综述,并分析了各种方法的优缺点.     

种植模式对当归根际细菌群落多样性及代谢通路的影响

连作障碍严重限制了当归产业的可持续发展.为了探索当归(Angelica sinensis)高效栽培技术,本研究在当归主产区甘肃省渭源县设置5种种植模式(A:豌豆-当归-当归,对照;B:豌豆-小麦-当归;C:豌豆-蒙古黄芪-当归;D:豌豆-马铃薯-当归;E:豌豆-休耕-当归),于采挖期分别测定不同种植模式下,当归根际土壤...     

斜纹夜蛾抗药性监测及茚虫威对其解毒代谢酶的影响

【目的】斜纹夜蛾Spodoptera litura (Fabricius)是主要的农业害虫之一。本研究旨在明确该害虫在湖南省5个主要蔬菜种植区的抗药性水平,并探讨该害虫对茚虫威的抗性与解毒代谢酶活性之间的关系,为斜纹夜蛾有效防控及抗性治理提供依据。【方法】采用浸叶法测定了2014-2016年湖南5地斜纹夜蛾田间种群对10种杀虫剂的抗性水平;将斜纹夜蛾敏感种群3龄幼虫在死亡率40%~70%的选择压下用茚虫威进行汰选,比较了斜纹夜蛾敏感种群和抗茚虫威种群的羧酸酯酶、谷胱甘肽S-转移酶和多功能氧化酶对硝基苯甲醚O-脱甲基活性。【结果】湖南5地斜纹夜蛾田间种群对有机磷类杀虫剂产生了26.9~220.2倍的抗性,对氨基甲酸酯类杀虫剂产生了68.3~890.8倍的抗性,对拟除虫菊酯类杀虫剂产生了21.0~267.2倍的抗性,对相对较新型杀虫剂（甲维盐、阿维菌素、茚虫威和溴虫腈）产生了5.2~53.4倍的抗性。经茚虫威汰选后第14代[抗性倍数(resistance ratio, RR)=26.43]斜纹夜蛾羧酸酯酶、谷胱甘肽S-转移酶和对硝基苯甲醚O-脱甲基酶活性分别上升2.86, 1.01和1.83倍。【结论】斜纹夜蛾对多种药剂产生了不同水平的抗性,斜纹夜蛾幼虫羧酸酯酶和对硝基苯甲醚O-脱甲基活性增强可能是斜纹夜蛾对茚虫威的抗性上升的重要因素。