An in computo investigation of the Landau-Kleffner syndrome

We describe a computational model of the thalamus and the cortex able to reproduce some essential epileptiform features commonly observed in the Landau-Kleffner syndrome. Investigation with this realistic model leads us to the formulation of a cellular mechanism that could be responsible for the epileptic discharges occuring with this severe syndrome. Understanding this mechanism is of prime importance for developing new therapeutical strategies. © 2007 IEEE.

Feeding rates affect heat shock protein levels in liver of larval white sturgeon (Acipenser transmontanus)

A two-week trial was conducted to study the effect of feeding rates on heat shock protein levels in larval white sturgeon. The larvae (30 day post hatch, 230 mg initial body weight) were fed a commercial feed (12.6% moisture, 49.5% crude protein. 20.7% Crude fat, and 8.6% ash) at 5, 15. or 25% body weight per clay (BW d(-1)). Liver heat shock proteins (Hsp) were measured before and after the larvae were subjected to a heat shock from 18 to 26 degrees C at 1 degrees C/15 min and maintained at 26 degrees C for 4 h thereafter. Before heat shock, larvae fed 5% BW d(-1) had significantly (P<0.05) lower final body weight, RNA/DNA ratio, whole body lipid and protein content, and Hsp60 and Hsp70 levels but higher protein efficiency ratio, and whole body moisture content than larvae fed the two higher feeding rates. Heat shock significantly induced Hsp60 and Hsp70 levels in the liver of all fish but they were lower in larvae fed the 5% than those fed 15 and 25% BW d(-1). Hsp70 level increased much more than Hsp60 after the heat shock Suggesting that Hsp70 is a more sensitive biomarker under our experimental conditions. (c) 2008 Elsevier B.V. All rights reserved.

Application of methyl parathion hydrolase (MPH) as a labeling enzyme

Methyl parathion hydrolase (MPH) is an enzyme that catalyzes the degradation of methyl parathion, generating a yellow product with specific absorption at 405 nm. The application of MPH as a new labeling enzyme was illustrated in this study. The key advantages of using MPH as a labeling enzyme are as follows: (1) unlike alkaline phosphatase (AP), horseradish peroxidase (HRP), and glucose oxidase (GOD), MPH is rarely found in animal cells, and it therefore produces less background noise; (2) its active form in solution is the monomer, with a molecular weight of 37 kDa; (3) its turnover number is 114.70 +/- 13.19 s(-1), which is sufficiently high to yield a significant signal for sensitive detection; and (4) its 3D structure is known and its C-terminal that is exposed to the surface can be easily subjected to the construction of genetic engineering monocloning antibody-enzyme fusion for enzyme-linked immunosorbent assay (ELISA). To demonstrate its utility, MPH was ligated to an single-chain variable fragment (scFv), known as A1E, against a white spot syndrome virus (WSSV) with the insertion of a [-(Gly-Ser)(5)-] linker peptide. The resulting fusion protein MPH-A1E possessed both the binding specificity of the scFv segment and the catalytic activity of the MPH segment. When MPH-A1E was used as an ELISA reagent, 25 ng purified WSSV was detected; this was similar to the detection sensitivity obtained using A1E scFv and the HRP/Anti-E Tag Conjugate protocol. The fusion protein also recognized the WSSV in 1 mu L hemolymph from an infected shrimp and differentiated it from a healthy shrimp.

Identification of a WSSV neutralizing scFv antibody by phage display technology and in vitro screening

White spot syndrome virus (WSSV) is one of the most significant viral pathogens causing high mortality and economic damage in shrimp aquaculture. Although intensive efforts were undertaken to detect and characterize WSSV infection in shrimp during the last decade, we still lack methods either to prevent or cure white spot disease. Most of the studies on neutralizing antibodies from sera have been performed using in vivo assays. For the first time, we report use of an in vitro screening method to obtain a neutralizing scFv antibody against WSSV from a previously constructed anti-WSSV single chain fragment variable region (scFv) antibody phage display library. From clones that were positive for WSSV by ELISA, 1 neutralizing scFv antibody was identified using an in vitro screening method based on shrimp primary lymphoid cell cultures. The availability of a neutralizing antibody against the virus should accelerate identification of infection-related genes and the host cell receptor, and may also enable new approaches to the prevention and cure of white spot disease.

Isolation and identification of a novel WSSV nucleocapsid protein by cDNA phage display using an scFv antibody

In a previous study, a scFv phage display library against white spot syndrome virus (WSSV) was constructed and yielded a clone designated A I with conformational specificity against native but not denatured viral antigen. Although the clone A1 has been used successfully as a diagnostic antibody, its precise target antigen has not been elucidated. A different strategy was adopted involving the construction of a second T7 phage display library utilizing mRNA isolated from shrimp infected with WSSV. Following RT-PCR and T7 phage library construction, phages displaying the candidate epitope were selected with A I scFv. Since successive enrichment steps were not associated with an increased titer of the phages, enrichment after successive tests was confirmed by PCR resulting in the prefer-red selection of a specific DNA sequence encoding a novel nucleocapsid protein WSSV388. Immune electron microscopy revealed that WSSV388 is located on the nucleocapsid. This result demonstrated that unknown antigen could be identified by phage display using the epitope conformation dependent scFv. (c) 2006 Elsevier B.V. All rights reserved.

Effects of feeding rate on growth performance of white sturgeon (Acipenser transmontanus) larvae

Four 1-week trials were conducted to determine the effects of feeding rates on growth performance and body proximate composition of white sturgeon larvae during each of the first 4 weeks after initiation of feeding. Feeding rates (% body weight day(-1)) were 10, 20, 30, 40, 50, and 60 for trial I; 5, 10, 15, 20, 25, and 30 for trial II; and 2.5, 5.0, 7.5, 10.5, 12.5, and 15.0 for trials III and TV Four tanks with 200 larvae each were randomly assigned to each of the six feeding rates. Average initial body weights of the larvae were 49, 94, 180, and 366 mg, respectively, for trials I-IV. The larvae were kept at 19-20 degreesC in circular tanks and fed continuously one of two commercial salmonid soft-moist feeds using automatic feeders. Proximate composition (%) of the feeds for trials I-III and IV were 13.9 and 14.9 moisture, 52.5 and 50.0 crude protein, 10.3 and 12.9 crude fat, and 8.1 and 8.7 ash, respectively. Except mortality in trial I, gain per food fed in trial III, and body ash in all trials, growth performance and body composition were significantly (P<0.05) affected by all feeding rates. Broken line analysis on specific growth rates indicated the optimum feeding rates of white sturgeon larvae to be 26%, 13%, 11%, and 6% body weight day-respectively, for weeks 1, 2, 3, and 4 after initiation of feeding. (C) 2003 Elsevier Science B.V. All rights reserved.

Characterization of an iridovirus from the cultured pig frog Rana grylio with lethal syndrome

Three virus isolates, RGV-9506, RGV-9807 and RGV-9808, were obtained from cultured pig frogs Rana grylio undergoing lethal infections. Previously, the first isolate, RGV-9506, was shown to be an iridovirus based on ultrastructural and morphological studies. In the present study, the original isolate, along with 2 recent ones, were more extensively characterized by experimental infection studies, histopathology, electron microscopy, serological reactivity, gel electrophoresis of viral polypeptides and DNA restriction fragments, PCR amplification, and nucleic acid sequence analysis of the major capsid protein (MCP) gene. The 3 isolates were shown to be identical to each other, and very similar to FV3, the type species of the genus Ranavirus (family Iridoviridae). These results suggest that RGV should be considered a strain of FV3, and indicate that FV3-like iridoviruses are capable of causing widespread, severe disease among cultured frogs.

Growth performance of juvenile white sturgeon as affected by feeding regimen

Juvenile (mean +/- SE, 8.6 +/- 0.1 g) white sturgeon Acipenser transmontanus were fed for 8 weeks under one of six feeding regimens: continuously 24 h/d (C24); continuously 12.8 h/d during the day (C12/D), continuously 12.8 h/d at night (C12/N), 6 meals/d (M6), 4 meals/d (M4), and 2 meals/d (M2). Specific growth rate, feed efficiency, and body lipid content were significantly (P < 0.05) affected by the feeding regimen. These variables were highest in the C24 group and lowest in the M2 group; fish in the M6 group showed the second best performance. Specific growth rate and feed efficiency in terms of wet weight in the M6 groups were not significantly different from those in the C24 groups, but specific growth rate in terms of energy and energy retention efficiency were significantly lower. Feeding regimen had no effect on condition factor, hepatosomatic index, coefficient of variation in final body weight, and protein and ash contents. There was no significant difference in these indexes between 12.8-h/d continuous feeding by day or by night. It was concluded that continuous feeding for 24 h/d was the optimum feeding regimen for juvenile white sturgeon.

Effect of feeding strategy and carbohydrate source on carbohydrate utilization by white sturgeon (Acipenser transmontanus) and hybrid tilapia (Oreochromis niloticus X O-aureus)

Two 8-week growth trials were conducted to determine the effect of continuous (CF) versus 2 meals day(-1) (MF) feeding and 30% starch versus 30% glucose diets on the carbohydrate utilization of 9.0-g white sturgeon and 0.56-g hybrid tilapia. The two trials were conducted under similar conditions except that sturgeon were kept at 18.5 degrees C in a flow-through system and tilapia were kept at 26 degrees C in a recirculating system. Significantly (P less than or equal to 0.05) higher specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER), body lipid content and liver glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) activities were observed in the CF than MF sturgeon. Only SGR, FE and PER were higher in sturgeon fed the starch than the glucose diets. Only higher liver G6PDH and malic enzyme (ME) activities were observed in the CF than MF tilapia but higher SGR, FE, PER and liver G6PDH, 6PGDH and ME activities were observed in tilapia fed the starch diet than those fed the glucose diet. This suggested that carbohydrate utilization by sturgeon was more affected by feeding strategy whereas tilapia was more affected by carbohydrate source. Furthermore, white sturgeon can utilize carbohydrates better than hybrid tilapia regardless of feeding strategy and carbohydrate source.

Effect of ration and body size on the energy budget of juvenile white sturgeon

Growth and energy budget were measured for three sizes(2.4, 11.1 and 22.5 g) of juvenile white sturgeon Acipenser transmontanus held at 18.5 degrees C and fed tubificid worms at different levels ranging from starvation to ad libitum. For each size-class, specific growth rate increased linearly with increasing ration, and conversion efficiency was highest at the maximum ration. Growth rate decreased with increasing fish size at the maximum ration, but increased with size al each restricted ration. Conversion efficiency increased with increasing ration for each size-class and was usually highest at the maximum ration. Faecal production accounted for 3.2-5.2% of food energy. The proportion of food energy lost in nitrogenous excretion decreased with increasing ration. With increases in ration, the allocation of metabolizable energy to metabolism decreased, while that to growth increased. Fish size had no significant effect on the allocation of metabolizable energy to metabolism or growth. Al the maximum ration, on average 64.9% of metabolizable energy was spent on metabolism, and 35.1% on growth. (C) 1996 The Fisheries Society of the British Isles

Phosphor-conversion white light using InGaN ultraviolet laser diode

We fabricated a phosphor-conversion white light using an InGaN laser diode that emits 405 nm near-ultraviolet (n-UV) light and phosphors that emit in the blue and yellow regions when excited by the n-UV and blue light, respectively.The relationship of the luminous flux and the luminous efficacy of the white light with injection current was discussed. The luminous flux increased linearly with increasing current above the threshold of the laser diode, and at 80 mA injection current, the luminous flux and luminous efficacy were estimated to be 5.7 lm and 13 lm/w, respectively. The shift of the Commission International de I'Eclairage coordinates, color temperature, and color rendering index with current are very slight and negligible, which indicates that the blue and the yellow phosphors have an excellent stability and a highly stable white light can be obtained by this way. (c) 2008 American Institute of Physics.

White light emission from ultraviolet laser diode

A phosphor-conversion white light using an InGaN laser diode that emits 405 nm near-ultraviolet (n-UV) light and phosphors that emit in the red/green/blue region when excited by the n-UV light was fabricated. The relationship of the luminous flux and the luminous efficacy of the white light with injection current were discussed. Based on the evaluation method for luminous efficacy of light sources established by the Commission International de I'Eclairage (CIE) and the phosphor used in this experiment, a theoretical analysis of the experiment results and the maximum luminous efficacy of this white light fabrication method were also presented.