Impact of yellow head virus outbreaks in the whiteleg shrimp,Penaeus vannamei (Boone), in Thailand

Yellow head virus (YHV) is known as a major pathogen in the black tiger shrimp, Penaeus (Penaeus) monodon. It can also cause serious mortality in farmed whiteleg shrimp, Penaeus (Litopenaeus) vannamei. However, there is no published information on the economic and/or production impact of the disease in P. vannamei. Shrimp with gross signs of YHV disease (faded body colour and 60–70% mortality) were observed in 20 study farms rearing P. vannamei in the central part of Thailand from the end of 2007 through early 2008. The estimated economic loss for these farms according to the Thai Animal Aquaculture Association was approximately US$3 million. Detailed sequence analysis of RT‐PCR amplicons from shrimp in all the study ponds revealed the presence of YHV Type 1b (YHV‐1b) alone (characterized by a 162‐bp deletion in the ORF3 region encoding the structural gene for gp116) and the absence of YHV Type 1a (YHV‐1a), the original YHV type reported from Thailand. Despite the large 162‐bp deletion (= 54 deduced amino acids) in the gp116 structural gene, histopathology of YHV‐1b infections was identical to that of YHV‐1a infections, and electron microscopy revealed that YHV‐1b virions were morphologically indistinguishable from those previously reported for YHV‐1a. In addition, an existing commercial RT‐PCR detection kit and an immunochromatographic test strip for the detection of YHV were proven to have been valid tests for both YHV‐1b and YHV‐1a. The source of the virus for these outbreaks was unlikely to have been the post‐larvae used to stock the ponds, as they were derived from domesticated specific pathogen‐free stocks free of YHV. Thus, it is possible that they originated from an unknown, natural reservoir.     

Mushroom tyrosinase: recent prospects

Tyrosinase, also known as polyphenol oxidase, is a copper-containing enzyme, which is widely distributed in microorganisms, animals, and plants. Nowadays mushroom tyrosinase has become popular because it is readily available and useful in a number of applications. This work presents a study on the importance of tyrosinase, especially that derived from mushroom, and describes its biochemical character and inhibition and activation by the various chemicals obtained from natural and synthetic origins with its clinical and industrial importance in the recent prospects.     

Molecular characterization,tissue distribution of Follicle‐Stimulating Hormone (FSH) beta subunit and effect of kisspeptin‐10 on reproductive hormonal profile of Catla catla (Hamilton, 1822)

Gonadotropin (GTH) hormones are glycoprotein which stimulates gonadal maturation in vertebrates. Follicle stimulating hormone is involved in initiation of gametogenesis and regulation of gonadal growth. FSHβ has been cloned and characterized from the brain of Catla catla. The FSHβ full‐length of cDNA sequence of 523 bp comprised 3, 394 and 128 bp of 5′‐UTR, open reading frame (ORF) 3′‐UTR respectively. The coding region of C. catla FSHβ encoded a peptide of 130 amino acids. Phylogenetic analysis of C. catla FSHβ deduced amino acid sequence showed high similarity with Gobiocypris rarus followed by goldfish, Carassius auratus. The qPCR result shows that FSHβ mRNA is mainly expressed in pituitary while moderate and low expression was observed in testis and ovary respectively. Chitosan‐nanoconjugated kisspeptin‐10 (CK‐10) of particle size 125 nm, polydispersity index of 0.335 to 0.65 and zeta potential of ?34.95 mV were synthesized and evaluated at against naked kisspeptin‐10 for their reproductive hormonal profile. Treatment of fish with CK‐10 showed controlled and sustained surge of the reproductive hormones (FSH & LH) with peak at 12 h. The hormone levels of naked kisspeptin‐10 treated fish decline after 6 h. The sustained release of this CK‐10 will help in reducing maturation age, synchronization of ovulation and spawning in fish. This is the first report on use of chitosan‐nanoconjugated kisspeptin‐10 (CK‐10) for reproduction in fish.     

饲料中添加强化爱渔灵对凡纳滨对虾生长、存活及免疫指标以及攻毒实验的影响

在实验室条件下研究了强化爱渔灵对凡纳滨对虾(Litopenaeus vannamei)生长、存活和免疫反应的影响。生长实验设计了三种颗粒饲料,分别添加不同含量的强化爱渔灵(0%、0.05%和0.1%),每个处理有6个重复,每个重复对应1个鱼缸,其中有25尾虾。生长实验进行60d,期间每天投喂实验饲料4次,日投饵率为3%。实验结果表明,生长实验40d后,0.1%强化爱渔灵组虾体重(16.76±1.33)g,显著高于0.05%强化爱渔灵组(15.84±0.99)g和对照组(15.40±1.19)g的体重(P<0.05)。两个实验组之间成活率(97.18%～97.60%)没有显著差异,但显著高于对照组的成活率(83.20%)(P<0.05)。通过总血细胞计数(THC)、吞噬百分率、酚氧化酶活力以及杀菌活性等评价了各处理组虾的免疫力。结果表明,0.1%添加组的THC值和吞噬百分率以及酚氧化酶活性显著高于0.05%添加组和对照组。0.1%添加组和0.05%添加组杀菌活性的血清稀释度为1:16,而对照组为1:8。生长实验60d后,对各处理组的虾肌肉注射哈维病毒,两个实验组均未发现死亡率,而对照组的死亡率达43.33%。同时,用白斑综合症病毒感染虾,两个强化爱渔灵添加组在感染7d后的死亡率达到100%,而对照组的死亡率在6d内就达到100%。各处理组虾在感染黄头病毒后的死亡率结果与白斑综合征病毒感染实验结果类似。本研究表明,在饲料中添加0.1%强化爱渔灵可显著改善凡纳滨对虾的生长、成活率以及免疫力。     

Effects of dietary Leucas aspera levels on growth performance,nutrient utilization,digestive enzymes and physio-metabolic and health status of bagrid catfish,Rita rita (Hamilton, 1822)

The study was to examine the effects of dietary L. aspera on growth performance, physio-metabolic response and health status of Rita rita fish reared in tanks for 60 days. Six experimental diets were formulated containing 0 g/kg, 3 g/kg, 6 g/kg, 9 g/kg and 12 g/kg L. aspera and designated as D0, D3, D6, D9 and D12 respectively. The inclusion of L. aspera at graded levels resulted in significantly varying effects on growth performance where the weight gain (%), specific growth rate (SGR) and feed conversion efficiency (FCE) were significantly higher (p<0.05) in D6 and D9 groups than others. The protease and amylase activities were elevated in L. aspera supplemented groups than the control group (p<0.05), whereas lactate dehydrogenase, malate dehydrogenase and serum transaminase enzyme activities were significantly reduced with the increasing level of L. aspera and comparatively higher activities of the respective enzymes were found in the control group. The activities of oxidative stress enzymes were significantly higher (p<0.05) in the D9 group and lower in control. The blood glucose level significantly decreased with the increasing level of L. aspera in the experimental diets. The L. aspera supplemented fish had significantly higher liver glycogen, serum protein, albumin and globulin than control group. Red blood cell count was significantly higher (p<0.05) in D6-D12, whereas white blood cell count and haemoglobin content were significantly higher (p<0.05) in D6 and D9 groups. Regression analysis showed that L. aspera at the level of 7.3–7.9 g/kg is optimum for better growth and feed efficiency.     

Pharmacokinetics,optimal dosages and withdrawal time of florfenicol in Asian seabass (Lates calcarifer) after oral administration via medicated feed

Asian seabass (Lates calcarifer) is an economically important fish in Asian and Australian markets, but few pharmacokinetic (PK) data of antimicrobial drugs in this species is available. The present study investigated the PK behaviour of florfenicol (FF) through medicated feed in Asian seabass cultured at 25°C. The serum and muscle/skin concentrations of FF and its metabolite florfenicol amine (FFA) were determined by the HPLC-FLD method and analysed by one-compartmental model. The optimal dosages were determined by pharmacokinetic-pharmacodynamic (PK-PD) approach and the linear regression analysis was used to determine the withdrawal time (WDT). The PK study following a single oral administration of 15 mg/kg FF via medicated feed revealed that the absorption half-life (t_1/2Ka), elimination half-life (t_1/2K), peak concentration (C_max), area under the concentration-time curve (AUC), volume of distribution (Vd/F) and clearance (CL/F) were 1.47 h, 8.07 h, 8.61 μg/ml, 146.41 h·μg/ml, 1.19 L/kg and 0.102 L/kg/h, respectively. The muscle/skin concentration-time profile was similar to that of the serum, suggesting well distribution but only a small fraction of FF was metabolized to FFA. The optimal dosage for a minimum inhibitory concentration of 2 μg/ml was calculated as 13.38 mg/kg/day. The appropriate WDT after multiple oral medications with 15 mg/kg FF once daily for 7 days was determined as 8 days. Information obtained from the current study can potentially be applied for the treatment of bacterial diseases in farming Asian seabass.     

Antimicrobial activity of partially characterized analytes from Bacillus pumilus(B2)

This study was carried out to characterize the antimicrobial substance produced by the strain of Bacillus pumilus (B2) obtained from Novozymes Biologicals Inc. to compare its antimicrobial activity by agar well diffusion assay and bacteriocin activity assay via critical dilution method against seven different strains of Vibrio spp., specifically V. alginolyticus (A01), V. cholerae (C01), V. fluvialis (F01, F02), V herveyii (H), V. mimicus (M01), V. parahaemolyticus (P01) and V. vulnificus (V01, V02). All Vibrio spp. were isolated from the hemolymph and intestine of the white faeces disease‐infected moribund pacific white‐leg shrimp Litopenaeus vannamei (Boone 1931) and one strain (V. harveyi) from its diseased postlarva. The cell‐free neutralized supernatant (CFNS) of B2 showed moderate thermo‐stability being stable up to 70°C for 60 min with, however, reducing activity above 80°C for 20 min. B2 antimicrobials showed a stable activity within the pH ranging from 6 to 10 at room temperature and at 4°C, while residual antimicrobial activity of crude CFNS showed tolerance to salinity up to 7% of sodium chloride below 4°C. No B2 activity was obtained while exposed to proteolytic enzyme, such as proteinase k and pepsin, while its activity kept stable exposed to lipase. Initial B2 characterization for antimicrobial substance in CFNS revealed proteinaceous in nature owing to activity loss against proteolytic enzymes and no lipid moiety activity against lipase, which could be categorized as bacteriocin‐like inhibitory substance having potential application against several strains of Vibrio spp. in aquaculture.     

Quantitative dissection of antioxidative bioactive components in cultivated and wild sesame germplasm reveals potentially exploitable wide genetic variability

Sesame (Sesamum indicum L.) is one of the oldest oilseed crops grown in India and worldwide. This oilseed crop has high nutritional value due to the presence of antioxidants such as lignans and tocopherols. Screening of oilseed germplasm for important nutritional attributes is of prime importance in quality breeding programs. In the present study, the content of lignans (sesamin and sesamolin) and tocopherol homologues (α-, γ-, and δ-tocopherol) was determined using reverse phase HPLC (RP-HPLC) in 143 sesame lines collected from diverse agro-ecological zones of India. Exploitable levels of sesamin, sesamolin, γ-, and δ-tocopherol was observed in the studied sesame lines. Sesamum indicum cultivar CO 1, introgressed line MKN 9, and Sesamum malabaricum showed high values for sesamin. Exotic and indigenous accessions of S. indicum (EC 542283 and IC 132176, IC 204681, IC 204773) showed high sesamolin contents. Cultivars, AKT 64, AKT 101, Phule til 1, and Tapi A showed high values for γ- and δ-tocopherol. The average content of sesamin and sesamolin was 0.86 and 0.50 mg g^?1 seed, respectively. The average tocopherol content (292 μg g^?1 seed) found in this study indicates the presence of a high amount of tocopherol in Indian sesame germplasm. Superior genotypes of sesame reported in this study could be utilized in sesame breeding programs for enhancing oil yield and nutritional attributes.