Production of gamma-linolenic acid by disrupted mycelia of Mortierella isabellina

AIMS: To optimize the production of linolenic acid by disrupted mycelia of Mortierella isabellina. METHODS AND RESULTS: Effects of incubation conditions such as incubation time, pH of reaction mixture, concentration of Mg2+ or malate and incubation temperature on production of linolenic acid were studied. The production of gamma-linolenic acid reached 224 mg g-1 dry cells when the reaction mixture was composed of 1.0 g (dry mycelial mass) of disrupted mycelia of M. isabellina, 50 ml (50 mmol l(-1)) potassium phosphate buffer supplemented with 0.312 mmol l(-1) of Mg2+ and 10 mmol l(-1) of malate, pH 7.0 and incubated at 5 degrees C for 1 day. CONCLUSIONS: Incubation temperature, concentration of Mg2+ and malate showed major effects on the increased linolenic acid production. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights conditions for increasing gamma-linolenic acid production by cell-free mycelia of M. isabellina and an insight into rapidly gaining high production of polyunsaturated fatty acids.     

Kupffer cell-initiated remote hepatic injury following bilateral hindlimb ischemia is complement dependent

Intravital fluorescence microscopy was applied to the livers of male Wistar rats to test the hypothesis that complement mobilization stimulates Kupffer cells and subsequently initiates hepatic injury after hindlimb ischemia/reperfusion (I/R). Following 3 h of limb reperfusion, hepatocellular viability (serum levels of alanine transaminase and cell death via propidium iodide labeling) decreased significantly from levels in sham-operated animals. Inhibition of complement mobilization with soluble complement receptor type 1 (20 mg/kg body wt) and interruption of Kupffer cell function with GdCl(3) (1 mg/100g body wt) resulted in significant hepatocellular protection. Although the effects of hindlimb I/R on hepatic microvascular perfusion were manifest as increased heterogeneity, both complement inhibition and suppression of Kupffer cell function resulted in marked improvements. No additional hepatocellular protection and microvascular improvements were provided by combining the interventions. Furthermore, inhibition of complement mobilization significantly depressed Kupffer cell phagocytosis by 42% following limb reperfusion. These results suggest that the stimulation of Kupffer cells via complement mobilization is necessary but is not the only factor contributing to the early pathogenesis of hepatic injury following hindlimb I/R.     

Occurrence of Bothriocephalus acheilognathi in cyprinid fish from three lakes in the flood plain of the Yangtze River, China

Cyprinid fish, Hemiculter leucisculus, Cultrichthys erythropterus and Culter dabryi, were sampled from Liangzi, Honghu and Tangxun lakes in the flood plain of the Yangtze River. The cestode Bothriocephalus acheilognathi Yamaguti, 1934 was found in the 3 lakes, but C. erythropterus sampled from Liangzi lake was found uninfected due probably to the small sample size. Findings of the cestode in the 3 lakes represent the first record of the parasite in the flood plain of the Yangtze River, indicating that B. acheilognathi may be distributed much wider in China than previously recognized.     

Stimulation of p53 DNA binding by c-Abl requires the p53 C terminus and tetramerization

The carboxyl terminus of p53 is a target of a variety of signals for regulation of p53 DNA binding. Growth suppressor c-Abl interacts with p53 in response to DNA damage and overexpression of c-Abl leads to G(1) growth arrest in a p53-dependent manner. Here, we show that c-Abl binds directly to the carboxyl-terminal regulatory domain of p53 and that this interaction requires tetramerization of p53. Importantly, we demonstrate that c-Abl stimulates the DNA-binding activity of wild-type p53 but not of a carboxyl-terminally truncated p53 (p53Delta363C). A deletion mutant of c-Abl that does not bind to p53 is also incapable of activating p53 DNA binding. These data suggest that the binding to the p53 carboxyl terminus is necessary for c-Abl stimulation. To investigate the mechanism for this activation, we have also shown that c-Abl stabilizes the p53-DNA complex. These results led us to hypothesize that the interaction of c-Abl with the C terminus of p53 may stabilize the p53 tetrameric conformation, resulting in a more stable p53-DNA complex. Interestingly, the stimulation of p53 DNA-binding by c-Abl does not require its tyrosine kinase activity, indicating a kinase-independent function for c-Abl. Together, these results suggest a detailed mechanism by which c-Abl activates p53 DNA-binding via the carboxyl-terminal regulatory domain and tetramerization.     

alpha-Amylase immobilized on bulk acoustic-wave sensor by UV-curing coating

A new method for immobilization of alpha-amylase by UV-curing coating is proposed in this paper. The immobilization procedure of UV-curing coating on piezoelectric quartz crystal is simple and convenient, and causes less loss of enzymatic activity. The activity of the immobilized alpha-amylase is monitored by a technique based on bulk acoustic-wave (BAW) sensor. The frequency shift of BAW sensor can reflect the degree of hydrolysis of starch by the immobilized alpha-amylase. It is appropriate for the immobilized alpha-amylase to hydrolyze the soluble starch under pH 7.0 condition, which is similar to that of the free alpha-amylase. Kinetic parameters (the Michaelis constant, K(m), and the maximum initial rate V(max)) of the enzymatic hydrolysis of starch by the immobilized alpha-amylase are estimated by using a linear method of Lineweaver-Burk plot. K(m)=12.7mgml(-1) and V(max)=15.9Hzmin(-1). And the experimental results show that the immobilized alpha-amylase entrapped by the UV-curing coating retains adequate enzymatic activity and can be reused more than 50 times under certain experimental conditions.     

Rational design of selective antimetabolites of DNA-thymine biosynthesis: 5-propynylpyrimidine nucleoside derivatives

A novel series of 5-propynylpyrimidine nucleosides are proposed as potential antimetabolites of DNA-thymine biosynthesis. This proposal is based on the results of detailed mechanistic analyses of the molecular interactions between dTMP synthase and its inhibitors. It is proposed that a propynyl side-chain at the 5-position of dUMP, bearing an appropriate leaving group, would cause irreversible inactivation of dTMP synthase, which would not require the presence of the cofactor, CH2H4folate.     

雌激素与阿尔采末病

阿尔采末病（ＡＤ）是一种慢性的大脑神经退行性变性疾病,主要表现为进行性远近记忆力障碍、语言、情感、认知、行为等方面改变。近年研究发现,ＡＤ的发病与雌激素缺乏有密切关系。雌激素可通过多种途径、环节延缓ＡＤ发生、发展。如促进可溶性β－淀粉样蛋白（Ａβ）生成,维持中枢神经元组织结构,影响中枢神经递质含量、酶活性、载脂蛋白Ｅ（ａｐｏＥ）生成及抗氧化等。目前,雌激素作为预防和治疗ＡＤ的药物日益受到重视,可望     

天花粉收白诱发白血病细胞K562凋亡的研究

Trichosanthin (TCS), an eukaryotic ribosome-inactivating protein isolated from the root tuber of Trichosanthes plant, has various biological activities including abortion induction, antitumor, and anti-HIV. In this study, cultured human leukemia K562 cells treated with trichosanthin were examined. Analysis of the cells by single laser flow cytometry showed the sub-G1 peak. DNA extracted from these cells formed a characteristic "ladder" on agarose gel electrophoresis. Under electromicroscope, typical morphological changes of apoptosis were also observed. From all of these findings, we concluded that trichosanthin was able to induce apoptosis in K562 cells.     

对鲇鱼鳃部寄生的固着鳋的生态研究

作者研究了江西江口水库鲇鳃部寄生固着鳋的种群生态学及其对寄生部位的选择性。固着鳋的感染率和丰盛度表现出明显的季节变化,以夏初最高;其繁殖也具有季节性,怀卵个体的比例同样有夏初最高。固着鳋对寄生部位的选择性似乎与种群的数量有关,当种群数量高时更多的固着鳋分布于中间的鳃片上,对多种寄生虫同时寄生条件下固着鳋寄生部位选择性的研究,将有助于进一步了解固着鳋和寄生鲇鳃部其它种类的寄生虫之间的关系。