Extraction of Chitin from the Shell Wastes of Two Shrimp Species Fenneropenaeus semisulcatus and Fenneropenaeus indicus using Microorganisms

Traditionally, chitin is extracted from crustacean shells using chemical methods involving the use of strong acids and alkali. In this study, chitin was extracted from the shrimp shell waste using microbes isolated from the fermented milk and bread. The chitin yield from the shells of Fenneropenaeus semisulcatus was 14.054% and 16.062%, respectively, for shell:bacterial broth ratios of 1:15 and 1:25; whereas, the yield of chitin from the shells of Fenneropenaeus indicus was 14.93% and 13.871%, respectively, at 1:15 and 1:25 broth ratios. The Fourier transform infrared spectra obtained from the chitin samples showed characteristic chitin peaks in both shell to bacterial broth ratio. The X-ray diffraction analysis revealed peaks between 10–15 and 25–30 degrees in the chitin recovered from both species, though some variations between species were observed. In conclusion, results of the present study indicate that application of microorganisms for the extraction of chitin from the shrimp shell waste could be an alternative for the traditional chemical methods.     

Evaluation of a spray-dried artificial diet for larval culture of freshwater prawn, Macrobrachium rosenbergii, and striped bass, Morone saxatilis

Larvae of the freshwater prawn, Macrobrachium rosenbergii (De Man), and the striped bass, Morone saxatilis (Walbaum), were fed artificial diets manufactured by a spray-drying process or live Artemia nauplii , separately or in various combinations. Spray-dried diets were neutrally buoyant, water stable (low protein leaching rate), and were satisfactorily consumed as verified by the observation of full guts after feeding. Survival and growth of larvae fed live Artemia nauplii was significantly greater than those of larvae fed spray-dried diets. Lowest survival and growth rates were observed when larvae were fed artificial diets exclusively from the onset of exogenous feeding. Survival rates were positively related to the duration of feeding live Artemia nauplii before weaning to artificial diets. The poor performance associated with spray-dried artificial diets may be the result of the digestive capabilities of the larvae of caridean shrimp and striped bass being insufficient to process compact, dense particles.     

First report of white spot syndrome virus in wild crustaceans and mollusks in the Paraíba River,Brazil

The aim of the present study was to investigate the presence of white spot syndrome virus (WSSV) in the Paraíba River, Brazil. Eight sampling sites were established on the bank of the river near water intake areas for the farming of Litopenaeus vannamei. Ten specimens of the shrimp Palaemon pandaliformis and the gastropods Pomacea lineata and Melanoides tuberculatus were collected at each site. Eighty‐one gill fragments from P. pandaliformis, 40 whole individuals of M. tuberculatus and 26 muscle fragments from P. lineata were collected. All samples were stored in microcentrifuge tubes with 95% ethanol (1:10; v:v). Tests were performed at the Potiporã Molecular Analysis Laboratory (state of Rio Grande do Norte, Brazil) for the detection of WSSV using Loop Mediated Isothermal Amplification with the aid of the LAMP WSSV kit (Concepto Azul, Ecuador). Twenty‐nine per cent of P. pandaliformis, 48% of M. tuberculatus and 8% of P. lineata tested positive. The findings demonstrate that WSSV is present in wild crustaceans and mollusks, which may serve as vectors and/or reservoirs of the virus, thereby posing a potential risk to local shrimp farming. This is the first report of WSSV in wild specimens of M. tuberculatus and P. lineata.     

青虾高血糖激素基因全长cDNA序列的克隆及表达分析

本研究首次克隆了青虾(Macrobrachium nipponense)高血糖激素(crustacean hyperglycemic homone,CHH)基因全长cDNA序列,并使用荧光定量PCR技术首次检测了CHH基因在青虾不同组织中的表达。青虾CHH基因cDNA全长1 017 bp,包括241 bp的5′UTR,408 bp的开放阅读框(ORF),355 bp的3′UTR,开放阅读框编码135个氨基酸。成熟肽包含6个CHH家族中位置保守的Cys残基。青虾CHH成熟肽C端为GK,确定为ES型CHH基因。蛋白相似度比对显示,所分离的青虾CHH被归为CHH家族I型肽。系统进化树分析表明,青虾CHH多肽与罗氏沼虾聚在一起,具有最近的亲缘关系。荧光定量PCR检测显示,CHH基因在青虾不同组织中均有表达,其表达量由高到依次为眼柄、精巢、腹神经节、脑、肠、肝、心脏、卵巢。以卵巢为参照其表达量设为1时,眼柄与精巢CHH基因表达量分别为卵巢的500倍和250倍,由此推测CHH基因可能与雄性生殖过程相关。     

Dietary astaxanthin supplementation for hatchery‐cultured red king crab,Paralithodes camtschaticus,juveniles

We conducted large‐scale production trials in Seward, Alaska, USA to investigate effects of dietary astaxanthin supplementation on survival, growth and shell colouration of recently settled juvenile (C1–C4) red king crabs (Paralithodes camtschaticus). We supplemented a control diet of commercial crustacean feeds with astaxanthin, and fed these diets to juvenile king crabs at densities of 2000 and 4000 crabs m^?2 for 56 days. We assessed survival and growth by counting crabs and individually measuring carapace width and weighing crabs at the start and end of the experiment, and quantified crab colour (hue, saturation, brightness) in digital photographs. Diets containing astaxanthin had higher survival, suggesting that astaxanthin may provide nutritional or immune system benefits. Crabs had lower hue, higher saturation and lower brightness values when fed diets containing astaxanthin, suggesting that red king crab colouration is plastic and responds to diet. Astaxanthin is likely an important dietary component for hatchery or laboratory reared red king crab juveniles, and should be considered for aquaculture and other rearing of this and possibly other crustacean species.     

Growth trajectory analysis of Pacific whiteleg shrimp (Litopenaeus vannamei): Comparison of the specific growth rate,the thermal‐unit growth coefficient and its adaptations

Empirical growth models have widespread application in the field of aquaculture. These models allow estimates of harvest size and waste outputs in addition to nutrient and feed requirements. In an effort to increase the ability to predict shrimp growth, the specific growth rate (SGR) and thermal‐unit growth coefficient (TGC) models were fitted to 15 datasets encompassing growth of Pacific whiteleg shrimp (Litopenaeus vannamei). Shrimp were reared under commercial conditions in Southeast Asia with weights ranging from 0.01 g to 34 g. Growth rates were regressed against body weights to identify changes in growth pattern across life stages. Analysis identified two distinct patterns of growth, with a break point between stanzas at 7.5 g. The body weight exponent of the TGC model, traditionally assumed to be (1 ? b) = 1/3, was solved for iteratively in each identified growth stanza in an effort to improve the goodness of fit of the TGC model. Average body weight exponents in the first and second stanzas were 0.416 and 0.952 respectively. Projected growth trajectories using these exponents resulted in significantly better fits in comparison to the traditional TGC and the SGR on the basis of statistical measures of goodness of fit.     

甲壳动物免疫系统回路分析

利用构建的甲壳动物免疫系统困,运用系统生物学方法对各免疫因子的相关关系进行探讨。将免疫系统困中重要的免疫因子抽象为节点,节点之间的边代表着因子之间的相关关系,则将整个免疫系统图抽象为一个充满节点的系统网络图。通过所构建的系统网络图,寻找了两个或多个因子之间的作用机制,以及各免疫路径之间的关系;利用建立的物理数学原理来揭示因子之间的免疫反应作用机制,解答免疫中的反应现象。揭示免疫刺激剂的免疫作用机理,促进整个免疫系统的免疫水平评价。     

Tilapia polyculture: a global review

Tilapia are the second most farmed fish worldwide and their production has quadrupled over the past decade due to ease of aquaculture, marketability and stable market prices. Tilapia aquaculture must adopt sustainable practices (such as polyculture) for continuing increased production and improved sustainability. This article reviews tilapia polyculture around the world and discusses its benefits, strategies and practices. Tilapia polyculture improves feed utilization, enhances water quality, increases total yield and profit. Further investment will increase these gains. Research on tilapia polyculture in China was also summarized and addressed that polyculture in semi‐intensive systems was a way of improving sustainability for tilapia aquaculture.     

A biophysical model to assess the trade‐off between larval recruitment and catch in southern Australia's largest prawn fishery

Data from stock assessment surveys, published research and climate sensors were linked to model the interaction between fishing, physical‐oceanographic processes and spatial patterns of larval settlement for western king prawn [Penaeus (Melicertus) latisulcatus]. This information was used to evaluate the trade‐off between larval recruitment and catch during fishing periods that demand high prices but coincide with spawning. Total rates of larval settlement were maximized when tidal currents and atmospheric physical‐forcing components were coupled with simulations of larval swimming behaviour under average gulf temperatures. Average gulf temperatures sustained longer larval durations and increased larval settlement rates by over 12% compared with warmer gulf conditions simulated under a scenario of global warming. Reproductive data coupled with outputs from the biophysical model identified consistent inter‐annual patterns in the areas contributing to larval settlement success. Areas located in the north‐east, and central‐west of the fishery, consistently contributed to over 40% of all larvae reaching a settlement in each year. Harvest sensitivity analyses indicated that changes in the spatial patterns of pre‐Christmas fishing could lead to improvements in overall rates of the larval settlement while maintaining or improving the levels of catch. Future studies to refine the model inputs relating to physical processes, larval behaviour and mortality rates for P. latisulcatus coupled with surveys of juvenile prawn abundance to ground truth the modelled predictions, would allow stock recruitment relationships to be more closely examined and inform adaptive management of the fishery in the future.     

三疣梭子蟹心激肽基因克隆及在低盐适应中的功能验证

采用RACE技术克隆获得三疣梭子蟹(Portunus trituberculatus)心激肽(CCAP)基因。该基因全长606 bp, 5￠端非编码区72bp,3￠端非编码区108bp,开放阅读框426bp,编码141个氨基酸,预测分子量15.6kD,理论等电点9.55。同源性分析表明,三疣梭子蟹CCAP与拟穴青蟹(Scylla paramamosain)和蓝蟹(Callinectes sapidus)的CCAP同源性较高,分别为85%和82%。系统进化树分析显示,三疣梭子蟹与蓝蟹首先聚为一支,之后再与拟穴青蟹相聚。组织表达分析发现, CCAP基因在胸神经节中的相对表达量最高,其次是脑和眼柄组织。通过分析CCAP基因在低盐胁迫过程中的表达规律发现,低盐可显著改变CCAP在胸神经节中的表达模式,在24 h, 48 h和72 h实验组的表达量显著高于对照组(P0.05),分别为对照组的1.73, 2.16和2.19倍。体外注射CCAP多肽可降低三疣梭子蟹在低盐条件下的死亡率,并诱发钠钾ATP酶(Na~+/K~+-ATPase)和V型ATP酶(V-ATPase)酶活力显著提高。本实验结果暗示CCAP通过调控Na~+/K~+-ATPase和V-ATPase活力以达到盐度适应的作用。