Regulation of oocyte maturation in the rainbow trout,Salmo gairdneri: role of cyclic AMP in the mechanism of action of the maturation inducing steroid (MIS), 17α-hydroxy, 20β-dihydroprogesterone

In fish, oocyte maturation (resumption of meiosis after completion of vitellogenesis and before ovulation) is triggered by maturation inducing steroids (MIS) which generally appear to be secreted in the ovary in response to stimulation by a pituitary maturational gonadotropin. Converging data from different laboratories show that 17-hydroxy, 20-dihydroprogesterone (17, 20-OH-P) is the principal MIS in salmonoids; but clear identification remains to be done in other taxonomic groups.The experiments reported here in the rainbow troutSalmo gairdneri examine the possible involvement of oocyte cAMP on the mechanism of MIS action. The action of 17, 20-OH-P, on germinal vesicle breakdown (GVBD) in oocytes incubatedin vitro within the follicle, was inhibited by various substances expected to elevate the intraoocyte concentrations of cAMP: cAMP ( 1 mM) or dibutyril cAMP ( 2 mM), phosphodiesterase inhibitors such as theophylline ( 0.2 mM) or 3-isobutyl-1 methylxanthine (IBMX 0.1 mM), adenylate cyclase activators such as cholera toxin (> 100 nM) or forskolin ( 0.03 mM). In fact, the combined action of IBMX (1 mM) and forskolin (0.01 or 0.05 mM)in vitro was to promote accumulation of intraoocyte cAMP within 1 to 5 hours. Oocyte cAMP concentrations exhibited a large variability between different females, depending on the stage of oocyte development; a significant positive correlation between oocyte cAMP concentration and the follicular weight, and a significant negative correlation between oocyte cAMP concentration and the median efficient dose of 17, 20-OH-P for induction of GVBD, were observed. Finally, when intrafollicular oocytes were incubatedin vitro, the addition of a maturation-inducing concentration of 17, 20-OH-P (3×10^–6M) induced a significant decrease of oocyte cAMP within the first 10 hours of incubation. These results show that cAMP appears to play a central role in the regulation of oocyte sensitivity to 17, 20-OH-P and in the intraoocyte mechanisms leading to GVBD in trout.These data are discussed together with the few indications available in fish concerning the mechanism of MIS action which can be compared to some extent with the amphibian model.     

不同生长期长白猪体脂代谢的特点与cAMP的调控作用

本文分析了６０－２４０日龄长白猪血中ｃＡＭＰ激光素敏感脂酶、游离脂脂酸和腺苷酸环化酶以及脂肪组织中ｃＡＭＰ、ＡＣ和各种脂酸组成。／     

Application and optimization of the tenderization of pig Longissimus dorsi muscle by adenosine 5'‐monophosphate (AMP) using the response surface methodology

Based on single factor experiments, NaCl concentration, adenosine 5'‐monophosphate (AMP) concentration and temperature were selected as independent variables for a three‐level Box‐Behnken experimental design, and the shear force and cooking loss were response values for regression analysis. According to the statistical models, it showed that all independent variables had significant effects on shear force and cooking loss, and optimal values were at the NaCl concentration of 4.15%, AMP concentration of 22.27 mmol/L and temperature of 16.70°C, which was determined with three‐dimensional response surface diagrams and contour plots. Under this condition, the observed shear force and cooking loss were 0.625 kg and 8.07%, respectively, exhibiting a good agreement with their predicted values, showing the good applicability and feasibility of response surface methodology (RSM) for improving pork tenderness. Compared with control pig muscles, AMP combined with NaCl treatment demonstrated significant effects on improvement of meat tenderness and reduction of cooking loss. Therefore, AMP could be regarded as an effective tenderization agent for pork.     

Signals controlling renin release in aglomerular toadfish

The toadfish,Opsanus tau, lacks renal glomeruli and macula densa, but has high renal renin activity and abundant granulated cells in renal arteries and arterioles. Reduction of blood pressure (BP) or blood volume by hemorrhage or vasodilatory drugs causes renin release, indicating that an intrarenal or extrarenal pressure- or volume-sensitive mechanism exists for controlling renin release in the toadfish. Thus, we examined whether 1) β-adrenergic receptor-mediated activation of renin release, and 2) calcium influx which may underlie the baroreceptor mechanism are involved in the cellular control of renin release. Acute injection of isoproterenol (1 μg/kg, n = 6) decreased BP and increased plasma renin activity (PRA) 4–5 fold in unanesthetized toadfish. Propranolol abolished both effects, but did not decrease basal PRA levels.In vitro superfusion of renal slices with bicarbonate Ringer's solution showed a steady secretion of renin, and addition of 50 mM K⁺ (K⁺ methylsulfate replacing NaCl, n = 10) to the superfusate markedly suppressed renin secretion. Nifedipine (10⁻⁵ M, n = 8) completely restored the high K⁺-induced inhibition of renin secretion from renal slices, whereas isoproterenol (10⁻⁴ M, n = 6) neither increased basal renin secretion nor restored K⁺-induced renin suppression. These results suggest that calcium influx may mediate inhibitory messages for renin secretion, while the β-adrenoceptor-mediated activation of granulated cells appears absent in toadfish.     

反相高效液相色谱法测定小鼠心肌中ATP、ADP和AMP含量及分析

建立同时测定小鼠心肌组织中ATP（三磷酸腺苷）、ADP（二磷酸腺苷）和AMP（一磷酸腺苷）含量的高效液相色谱方法。采用反相高效液相色谱模式,使用SepaxBio-C18（250ram×4．6mmID,μm,200A）色谱柱,以60mmoL·L^-1磷酸二氢钾、60mmoL·L^-1磷酸氢二钾组成的缓冲液（pH=6．68）为流动相等比洗脱,流速：O．6mL·min^-1紫外检测波长为259Nm,带宽为30nm。三种目标组分在10min内实现基线分离,平均加标回收率均在99％以上,线性范围为1-200mg·L^-1检出限分别为20、20、25ng。该法简便、准确,易于移植。     

农业机械化项目绩效模糊综合评价算法

对农业机械化项目的可实施性以及实施效果进行科学、合理、正确的评价,可为其进一步发展和长期规划提供有效的决策依据。由于其地域环境、发展阶段、产业结构的不同存在着诸多模糊性和不确定性,建立多层次多指标的模糊综合评价模型进行模糊评判是较为常用的评判方法。但现有的模糊隶属度转换算法存在着目标分类不明确和出现冗余数值的问题,采用基于熵的数据挖掘方法,通过定义指标区分权,清除对目标分类不起作用的冗余数值,实现正确的隶属度转换并用于农业机械化项目绩效模糊综合评价中,使评价结果更具真实性和可靠性。     

Ecklonia cava Polyphenol Has a Protective Effect against Ethanol-Induced Liver Injury in a Cyclic AMP-Dependent Manner

Previously, we showed that Ecklonia cava polyphenol (ECP) treatment suppressed ethanol-induced increases in hepatocyte death by scavenging intracellular reactive oxygen species (ROS) and maintaining intracellular glutathione levels. Here, we examined the effects of ECP on the activities of alcohol-metabolizing enzymes and their regulating mechanisms in ethanol-treated hepatocytes. Isolated hepatocytes were incubated with or without 100 mM ethanol. ECP was dissolved in dimethylsulfoxide. ECP was added to cultured cells that had been incubated with or without ethanol. The cells were incubated for 0–24 h. In cultured hepatocytes, the ECP treatment with ethanol inhibited cytochrome P450 2E1 (CYP2E1) expression and activity, which is related to the production of ROS when large quantities of ethanol are oxidized. On the other hand, ECP treatment with ethanol increased the activity of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase. These changes in activities of CYP2E1 and ADH were suppressed by treatment with H89, an inhibitor of protein kinase A. ECP treatment with ethanol enhanced cyclic AMP concentrations compared with those of control cells. ECP may be a candidate for preventing ethanol-induced liver injury via regulating alcohol metabolic enzymes in a cyclic AMP-dependent manner.     

氨卞西林钠和马来酰肼对菊花形态、花色和花期的影响

在秋菊品种姹紫嫣红的营养生长期,以氨卞西林钠(AMP 1000 mg/L)和不同浓度马来酰肼(MH 100 mg/L,200 mg/L和300 mg/L)的水溶液进行叶面喷雾处理,初步研究了AMP和MH对菊花绿蕾期叶片、盛花期植株与花瓣形态、花色和花期的影响。结果表明,AMP处理使菊花绿蕾期叶片叶绿素含量、干重/鲜重和叶面积均明显高于对照,始花日期比对照提早8.8 d,单花寿命、盛花期株高、株径、花瓣干重/鲜重和花青素含量也比对照明显提高,有助于提高菊花的观赏价值;MH处理提高了菊花的叶绿素含量,但明显降低了菊花的叶面积,延迟了菊花的花期,在MH100~300 mg/L范围内,对菊花的延迟效应为4.2~16.6 d,对菊花的观赏价值也有不同程度的降低效应,且随着MH浓度的提高,处理效应逐渐增强。     

家蚕抗菌肽基因研究进展

抗菌肽是昆虫先天性免疫系统中十分重要的效应因子,近年来一直是昆虫免疫学研究的热点。家蚕作为鳞翅目昆虫的代表,其抗菌肽研究取得了长足进展。根据已经研究获得的抗菌肽基因序列在家蚕基因组中进行同源搜寻,共获得了40个家蚕抗菌肽基因。这些基因编码的多肽在大小、氨基酸组成和性质上差异很大,但基于结构性质可以分成3类:(1)具有α-螺旋结构并且缺乏半胱氨酸(cysteine,Cys)的线性抗菌肽;(2)富含脯氨酸或甘氨酸的组成性抗菌肽;(3)富含半胱氨酸的环形抗菌肽。以这3类结构作为主线,综述了家蚕抗菌肽近年来的研究进展。     

Impact of cycloheximide addition on adenylates in soil

Cycloheximide inhibits specifically the ribosomal protein synthesis of eukaryotic cells, i.e. the metabolism of soil fungi. We measured cycloheximide effects on adenylates in 20 different soils (0-10 cm depth) from arable, grass and forest land with a large variety of soil properties. The aims were (1) to assess the interactions between cycloheximide effects and soil properties and (2) to prove the relationship between cycloheximide effects on ATP and the ergosterol-to-microbial biomass C ratio, which is an indicator for the fungal proportion of the total microbial biomass. The adenylates ATP, ADP and AMP were measured 6 h after adding either 10 mg cycloheximide per gram soil in combination with 24 mg talcum per gram soil or 24 mg talcum per gram soil solely. The medians of the relative increases in AMP and ADP were 45 and 25% and the medians of the relative decreases in ATP and adenylates were −36 and −12%. These changes in adenylate composition lead to a cycloheximide-induced relative decrease in the adenylate energy charge level of 15%. The relative decrease in ATP content after cycloheximide addition was significantly correlated with the ATP-to-microbial biomass C ratio, but not with the ergosterol-to-microbial biomass C ratio. The absolute increase in ADP and the absolute decrease in ATP were affected by the clay content according to principal component analysis. The reduction of the ATP-to-microbial biomass C ratio indicates that this ratio had the potential of being an important ecotoxicological indicator of direct toxic effects of organic pollutants on soil microorganisms.