Salt tolerance of bacteria isolated from tropical marine fish and prawn

Salt tolerance of selected cultures of Pseudomonas, Moraxella, Vibrio, Micrococcus, Acinetobacter and Flavobacteria/ Cytophaga was determined. More than 80% of the cultures belonging to each of the above genera, were capable of growth in presence of 1.5 to 3.5% salt (NaCl) and at least 25 to 30% of the cultures in each group required 1.5 to 3.5% salt for growth. 40% each of Pseudomonas and Vibrio strains and 30% each of Moraxella, Micrococcus and Flavobacteria/Cytophaga strains tolerated 10% salt. Majority of the cultures belonging to the genera Pseudomonas, Vibrio, Moraxella, Micrococcus, Acinetobacter and Flavobacteria/Cytophaga were slightly halophilic (2 to 5% salt tolerant), about 25% especially of Micrococcus spp. moderately halophilic (5 to 20% salt tolerant) and none from Pseudomonas, Vibrio, Moraxella, Acinetobacter and Flavobacteria/Cytophaga spp. extremely halophilic (20 to 32% salt tolerant).

Tolerance of Penaeus monodon larvae to cupric sulfate added in bath

Copper is used to deter the growth of bacterial, fungal and protozoan disease organism in fishes. Zoeae (Z SUB-1 ), myses (M SUB-1 ) and postlarvae (P SUB-1 ) were exposed to copper sulfate at concentrations of 0 . 025, 0 . 05, 0 . 75, 0 . 1 and 0 . 2 ppm from 24 to 96 hours. The number of surviving larvae were counted at the end of each 24-hour period and the percentage of survival is determined for each dose level. The LC SUB-50 for each of the larval stages was interpolated from the data whenever possible. Three trials with 2 replicates per trial were conducted. The physico-chemical characteristics of the bath taken before and at the end of the experimental period show insignificant differences between initial and final values in each trial. Results indicate that mortality rates of all larval stages increased with exposure time and that mortality rates of the experimental group is higher than the control. Interpolation of the LC SUB-50 is possible only for the 48-h and 72-h exposure times for both zoeae and myses and for the 48-h exposure time for the postlarvae. This is due to the high survival percentage of the 24-h group and the low survival percentage (below 50%) of the larvae exposed for 96 hours. The 48-hour LC SUB-50 for Z SUB-1 , M SUB-1 and P SUB-1 are 0 . 225, 0 . 350 and 0 . 125 ppm respectively. Postlarvae seem to be more sensitive than either of the 2 larval stages having a lower 48-h LC SUB-50 and a low survival rate after 72 hours. The larvae were observed to lose their balance and were lethargic, producing few swimming movements so that they were mostly confined to the bottom of the aquaria. Moribund larvae observed under the microscope had a faster but weak heartbeat compared to healthy larvae. Slight or complete loss of feeding ability indicated by empty guts and delayed molting of Z SUB-1 to Z SUB-2 were also noted.

Minimum dissolved oxygen tolerance of four different sizes of milkfish

Four size groups of milkfish were tested, 4-18 g, 20-34 g, 35-95 g and 200-300 g. A number of fish from each group were placed separately in identical 1.2 m2 wooden tanks containing seawater filled up to 30 cm depth. The aggregate weight of fish per size group was approximately 1 kg. The fish were held for 72 h, fed with lab-lab and provided with continuous aeration to allow recovery from stress during transport and handling. After the recovery period, aeration was stopped and 200 g of the fine rice bran was spread over the water in each tank creating a film of bran particles on the water surface. This was designed to speed up depletion of dissolved oxygen considering the combined effects of the screening-off of sunlight, the reduction of air-water interface and the breakdown of the bran particles. It is probable that stress on milkfish in brackishwater ponds could start when oxygen level drops to about 1.4 ppm. A further decrease to 0.04 ppm could produce a total kill of all specimens above 4 grams with marketable size and bigger size fish dying first.

EEG activities in the orbitofrontal cortex and dorsolateral prefrontal cortex during the development of morphine dependence, tolerance and withdrawal in rhesus monkeys

Investigating the activities of the prefrontal cortex (PFC) in the process of addiction is valuable for understanding the neural mechanism underlying the impairments of the PFC after drug abuse. However, limited data are obtained from primate animals and few studies analyze Electroencephalogram (EEG) in the gamma band, which plays an important role in cognitive functions. In addition, it is yet unclear whether drug abuse affects the orbitofrontal cortex (OFC) and dorsolateral PFC (DLPFC) - the two most important subregions of the PFC - in similar ways or not. The aim of this study is to address these issues. We recorded EEG in the OFC and DLPFC in three rhesus monkeys. All animals received a course of saline (NaCl 0.9%, 2 ml) injection (5 days) followed by 10 days of morphine injection (every 12 h), and then a further series of saline injection (7 days). A main finding in the present study was that morphine decreased EEG power in all frequency bands in a short period after injection in both the OFC and DLPFC in monkeys. And gamma power decreased not just in short period after morphine injection but lasted to 12 h after injection. Moreover, we found that although the changes in EEG activities in the OFC and DLPFC at 30-35 min after injection were similar, the DLPFC was more sensitive to the effect of morphine than the OFC. (c) 2005 Elsevier B.V. All rights reserved.

Enhancement of GABAA Receptor-Mediated Inhibitory Postsynaptic Currents Induced by "Partial Oxygen-Glucose Deprivation

下载PDF阅读器"氧糖剥夺"模型作为研究脑缺血的离体模型被广泛使用,该模型模拟了局灶性脑缺血的主要病理变化.然而在缺血病灶核心区与正常脑组织之间称为缺血半暗带的区域,脑血流也有程度不一的降低.为了模拟这种病理变化,发展了一种"不完全氧糖剥夺"的离体脑片模型,该模型满足两个条件,灌流液里氧气部分剥夺而葡萄糖含量降低;"氧糖剥夺"可以导致谷氨酸介导的兴奋性毒性,从而引起神经细胞的坏死.而A型γ-氨基丁酸受体(GABAAR)介导的神经元抑制性活动可以对抗谷氨酸引起的兴奋性毒性,因此近年来引起广泛的研究兴趣.而谷氨酸受体和γ-氨基丁酸受体功能在缺血半暗带是否有改变尚不得而知.因此本文采用海马脑片全细胞膜片钳的记录方法,研究"不完全氧糖剥夺"对海马CA1区神经元的A型γ-氨基丁酸受体介导的抑制性突触后膜电流(IPSCs)的影响.研究发现"不完全氧糖剥夺"使GABAAR介导的IPSCs的峰值增加而衰减时程延长.进一步研究发现该电流的峰值增加是由于GABAAR-氯离子通道的电导增加所致,而与氯离子的反转电位变化无关.这些发现提示在脑缺血的缺血半暗带区域GABAAR介导的神经元抑制性活动可能是增强的,这可能是神经元面对缺血状态产生自我保护的一种内稳态机制.

Enriched environment treatment restores impaired hippocampal synaptic plasticity and cognitive deficits induced by prenatal chronic stress

Prenatal stress can cause long-term effects on cognitive functions in offspring. Hippocampal synaptic plasticity, believed to be the mechanism underlying certain types of learning and memory, and known to be sensitive to behavioral stress, can be changed

Chronic Morphine Treatment Impaired Hippocampal Long-Term Potentiation and Spatial Memory via Accumulation of Extracellular Adenosine Acting on Adenosine A(1) Receptors

Chronic exposure to opiates impairs hippocampal long-term potentiation (LTP) and spatial memory, but the underlying mechanisms remain to be elucidated. Given the well known effects of adenosine, an important neuromodulator, on hippocampal neuronal excitability and synaptic plasticity, we investigated the potential effect of changes in adenosine concentrations on chronic morphine treatment-induced impairment of hippocampal CA1 LTP and spatial memory. We found that chronic treatment in mice with either increasing doses (20-100 mg/kg) of morphine for 7 d or equal daily dose (20 mg/kg) of morphine for 12 d led to a significant increase of hippocampal extracellular adenosine concentrations. Importantly, we found that accumulated adenosine contributed to the inhibition of the hippocampal CA1 LTP and impairment of spatial memory retrieval measured in the Morris water maze. Adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine significantly reversed chronic morphine-induced impairment of hippocampal CA1 LTP and spatial memory. Likewise, adenosine deaminase, which converts adenosine into the inactive metabolite inosine, restored impaired hippocampal CA1 LTP. We further found that adenosine accumulation was attributable to the alteration of adenosine uptake but not adenosine metabolisms. Bidirectional nucleoside transporters (ENT2) appeared to play a key role in the reduction of adenosine uptake. Changes in PKC-alpha/beta activity were correlated with the attenuation of the ENT2 function in the short-term (2 h) but not in the long-term (7 d) period after the termination of morphine treatment. This study reveals a potential mechanism by which chronic exposure to morphine leads to impairment of both hippocampal LTP and spatial memory.

Design of carbon nanotube fiber microelectrode for glucose biosensing

BACKGROUND: Carbon nanotube (CNT) fiber directly spun from an aerogel has a unique, well-aligned nanostructure (nano-pore and nano-brush), and thus provides high electro-catalytic activity and strong interaction with glucose oxidase enzyme. It shows great potential as a microelectrode for electrochemical biosensors. RESULTS: Cyclic voltammogram results indicate that post-synthesis treatments have great influence on the electrocatalytic activity of CNT fibers. Raman spectroscopy and electrical conductivity tests suggest that fibers annealed at 250 °C remove most of the impurities without damaging the graphite-like structure. This leads to a nano-porous morphology on the surface and the highest conductivity value (1.1 × 10 5 S m -1). Two CNT fiber microelectrode designs were applied to enhance their electron transfer behaviour, and it was found that a design using a 30 nm gold coating is able to linearly cover human physiological glucose level between 2 and 30 mmol L -1. The design also leads to a low detection limit of 25 μmol L -1. CONCLUSIONS: The high performance of CNT fibers not only offers exceptional mechanical and electrical properties, but also provides a large surface area and electron transfer pathway. They consequently make excellent bioactive microelectrodes for glucose biosensing, especially for potential use in implantable devices. © 2011 Society of Chemical Industry.

A critical review of Glucose biosensors based on Carbon nanomaterials: Carbon nanotubes and graphene

There has been an explosion of research into the physical and chemical properties of carbon-based nanomaterials, since the discovery of carbon nanotubes (CNTs) by Iijima in 1991. Carbon nanomaterials offer unique advantages in several areas, like high surface-volume ratio, high electrical conductivity, chemical stability and strong mechanical strength, and are thus frequently being incorporated into sensing elements. Carbon nanomaterial-based sensors generally have higher sensitivities and a lower detection limit than conventional ones. In this review, a brief history of glucose biosensors is firstly presented. The carbon nanotube and grapheme-based biosensors, are introduced in Sections 3 and 4, respectively, which cover synthesis methods, up-to-date sensing approaches and nonenzymatic hybrid sensors. Finally, we briefly outline the current status and future direction for carbon nanomaterials to be used in the sensing area. © 2012 by the authors; licensee MDPI, Basel, Switzerland.