Assessment of cholesterol requirements in the prawn, Penaeus japonicus

Two feeding experiments were conducted to assess the quantitative cholesterol requirement of the juvenile prawn, Penaeus japonicus . The prawns were fed casein-based (experiment 1) and casein- or crab protein-based (experiment 2) diets with or without supplemental cholesterol. The daily increases in quantities of body cholesterol (mg kg⁻¹ prawn day⁻¹) at maximum growth and dietary cholesterol intake over a 40-day feeding period were determined. Prawns fed 5 g kg⁻¹ supplemental cholesterol, regardless of protein sources, gave the highest weight gain. Body retention efficiencies of dietary cholesterol (cholesterol retained × 100/cholesterol intake) vary among prawns fed 5 g kg⁻¹ supplemental cholesterol (diets 3, 5 and 7) but dietary cholesterol requirements expressed as mg kg⁻¹ body weight (BW) day⁻¹ were not significantly different (180 to 200 mg kg⁻¹ BW day⁻¹). Based on dietary cholesterol requirement, the optimum dietary cholesterol levels for the juvenile prawns were estimated in relation to feeding levels. When feeding levels were 3%, 5% and 7% of body weight, optimum dietary cholesterol levels were 5.0 to 6.0, 3.6 to 4.0, and 2.6 to 2.9 g kg⁻¹ of dry diet, respectively. The present study showed the advantages of determining daily cholesterol requirement (mg kg⁻¹ BW day⁻¹) at maximum growth through a factorial method in determining optimum dietary cholesterol levels in P. japonicus .     

Relatedness structure estimated by microsatellites DNA and mitochondrial DNA polymerase chain reaction–restriction fragment length polymorphisms analyses in the wild population of kuruma prawn Penaeus japonicus

ABSTRACT: The genetic structure and variability of four wild populations of kuruma prawn in Japan were examined by estimating relatedness among individuals. The relatedness was estimated by five microsatellites (MS) DNA markers. Examination of relatedness showed that individuals were related significantly in Kumamoto and Kagoshima. In Kagoshima, some individuals showed full-sib level of relatedness. The analysis of mitochondrial (mt)DNA polymerase chain reaction–restriction fragment length polymorphisms (PCR-RFLP) was also performed, showing that the closely related individuals in Kagoshima tended to share a common haplotype. It is, therefore, supposed that there are many kins in Kumamoto and Kagoshima. However, the heterozygosities and allelic and genotypic frequencies in MS-DNA analysis were not significantly different among the localities. Moreover, the haplotype distributions of mtDNA in Kumamoto and Kagoshima were significantly different from other localities. Thus, it is suggested that no spatial differentiations occurred due to the geographic or historical effects between the localities and that there is the possibility of a mixture of hatchery populations in Kumamoto and Kagoshima.     

甲壳动物内分泌学研究与展望

在斑节对虾(Penaeus monodon)体内新发现了2种高血糖激素(crustacean hyperglycemic hormone, CHH)家族基因PmCHH和PmHHLPP。基因组分析结果显示,其均具有CHH-Ⅰ型基因基本的“信号肽-CPRP-KR/ER/RR-成熟肽”结构,且与已报道的CHHs基因的基因组结构相似;聚类分析结果显示,尽管PmCHH 和PmHHLPP与多个CHHs基因序列相似性超过50% (最高达99%),但与其聚为一支的基因均不是CHH-Ⅰ型基因;生物信息学分析结果显示,PmCHH和PmHHLPP的转录起始位点“A”及其核心启动子区域分别位于开放阅读框(ORF)上游的99 bp和190 bp,同时在预测其空间结构后发现,两者的三维结构中均含有4个α螺旋构型;组织表达结果显示,2个基因均在肠中有较高的表达量,而PmCHH在鳃、PmHHLPP在眼柄中表达量也较高,但在肝胰腺和肌肉中表达量较低;幼体发育阶段表达结果显示,2个基因在无节幼体Ⅲ~Ⅳ期、溞状幼体Ⅰ期和糠虾幼体期表达量均有较大波动,与代谢强度呈弱相关关系。根据其一级结构的特征和相关表达情况,可推测PmCHH和PmHHLPP均为CHHs家族基因。     

Inheritance mode of microsatellite DNA markers and their use for kinship estimation in kuruma prawn Penaeus japonicus

The allelic inheritance mode of microsatellite DNA markers was examined using seven copulated wild females and their offspring. Five microsatellite loci, CSPJ002 *, CSPJ010 *, CSPJ012 *, CSPJ014 *, and CSPJ015 *, were used in the study. At almost all family/locus combinations, one sire was determined and distributions of genotypes in offspring were consistent with the Mendelian segregation ratio. Distributions of genotypes were consistent with the ratio after assuming a null allele at some loci. Consequently, the alleles of CSPJ002 * and CSPJ012 * were inherited following the Mendelian inheritance mode in every family; however, the null allele was expected in CSPJ010 *, CSPJ014 *, and CSPJ015 * in some families. Thus, these loci should be used carefully in population genetic analysis, but siblings could be detected in the dendrograms based on unweighted pair-group method using arithmetic averages (UPMGA).     

日本对虾杆状核病毒性传染病诊断技术

本文提出了分别用暗视野显微技术和透射电子显微技术快速确诊日本对虾杆状核病毒性传染病的方法。在暗视野显微镜下观察到的血淋巴中的病毒粒子大小约为0.5μm;胃表层上皮被病毒感染的细胞核明显地呈白色均质小体,直径10～15μm,球形或椭圆形,坏死细胞被囊化为棕色小块(约20～50μm)。病虾血淋巴和胃经负染制样在透射电子显微镜下观察病毒颗粒大小为400×150nm;核衣壳大小为390×85nm。     

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。     

Comparison of spatiotemporal patterns in reproduction of the kuruma prawn Marsupenaeus japonicus between two regions having different geographic conditions in Kyushu, southern Japan

ABSTRACT:   The Yatsushiro Sea and Shibushi Bay are, respectively, located on the western and south-eastern coast of Kyushu, southern Japan. The Yatsushiro Sea is a shallow semi-enclosed inland sea, whereas Shibushi Bay is an open-type bay with a deep and wide mouth facing the open sea. The size at sexual maturity and spatiotemporal patterns of reproduction of the kuruma prawn Marsupenaeus japonicus (Decapoda, Penaeidae) were examined and compared between these two regions. In the Yatsushiro Sea, the size at sexual maturity was estimated to be 131 mm body length. However, the estimated size at sexual maturity was considerably larger (154 mm) in Shibushi Bay. The spawning season of M. japonicus was estimated to continue from April to September in the Yatsushiro Sea, whereas it was estimated to be longer in Shibushi Bay, from March to November. It is believed that the warm water temperature due to the strong effect of the Kuroshio Current prolonged the spawning season of M. japonicus in Shibushi Bay. The spawning grounds were estimated to be in areas deeper than 10 m in the Yatsushiro Sea and deeper than 20 m in Shibushi Bay. In Shibushi Bay, body size distribution of mature females was considered to be less affected by water depth in comparison with the Yatsushiro Sea, although older mature females larger than 200 mm body length also spawned outside of the bay.     

Effect of recombinant crustacean hyperglycemic hormones rCHH‐B1 and rCHH‐B2 on lipid metabolism in the Pacific white shrimp Litopenaeus vannamei

The crustacean hyperglycemic hormones (CHH) are pleiotropic neuropeptides controlling diverse processes in the life cycle of crustaceans. In the Pacific white shrimp Litopenaeus vannamei, CHH‐B1 and CHH‐B2 are generated by alternative splicing of the same gene, and the recombinant versions of these peptides have shown differential effects on glucose metabolism and osmoregulation in this species. In this work, we explored the role of both recombinant variants, expressed in yeast Pichia pastoris, on lipid metabolism. The results showed that rCHH‐B1 and rCHH‐B2 injections into eyestalk‐ablated shrimp significantly increased the phospholipid and triglyceride levels in haemolymph and restored free fatty acid levels, suggesting that these CHH variants mobilize lipid reserves in shrimp. The effects on lipids were concomitant to its hyperglycemic activity, suggesting that both variants, in addition to their hyperglycemic activity, have hyperlipidemic functions.     

Effects of stocking density on the nutrient budget and growth of the western king prawn (Penaeus latisulcatus Kishinouye) in a recirculating aquaculture system

Intensification in the commercial culture of prawns can have a significant impact on the water quality and hence on the survival, growth and the surrounding environment. The present study aims to evaluate the effects of stocking density on the water quality and performance of the western king prawns (Penaeus latisulcatus) and the nutrient budget of the culture environment. Four stocking densities of 4, 8, 16 and 32 prawns m^?2 were tested in 12 recirculating systems. Prawn weight and specific growth rate increased with decreasing stocking density, while the survival rate showed the reverse trend. The mean total ammonia nitrogen, nitrate nitrogen, total phosphorus and soluble reactive phosphorus were significantly higher (P<0.05) at the higher stocking density. The nutrient budget revealed that the prawns could assimilate only 9.34–20.13% nitrogen and 4.97–11.25% phosphorus of the total nutrient inputs. The drained water at harvest was the major sink of phosphorus and nitrogen at stocking densities of 4, 8 and 16, which accounted for 45.59–64.82% and 44.28–65.62% of the total inputs, respectively, while a significant proportion of nitrogen sunk into the sediment at 32 prawns m^?2. The study suggested that the stocking densities of western king prawns can be up to 16 prawns m^?2 in the recirculating water environment.