Establishment and characterization of a fin tissue cell line derived from silver pomfret,Pampus argenteus

A cell line (PaF) derived from the fin tissue of silver pomfret (Pampus argenteus) was established and characterized in this study. The cell line has been subcultured for more than 50 times in Dulbecco's modified Eagle's medium (DMEM) containing 15% foetal bovine serum (FBS) since the initial primary culture. PaF cells grew well at temperatures from 24°C to 28°C in DMEM supplemented with 15% FBS. Partial amplification and sequence analysis of the cytochrome B gene indicated that PaF originated from silver pomfret. Cytogenetic analysis demonstrated that the modal chromosome number was 48. A significant cytopathic effect was observed in PaF cells during viral haemorrhagic septicaemia virus (VHSV) infection, and the VHSV replication was confirmed by qRT‐PCR and viral titre assays. In contrast, PaF cells were resistant to red‐spotted grouper nervous necrosis virus infection. Moreover, PaF cells could respond to VHSV and lipopolysaccharide treatments, as indicated by the expression of immune‐related genes, TLR5 and TLR9. In conclusion, the establishment of PaF cell line will provide an appropriate in vitro tool for the study of mechanisms of pathogen–silver pomfret interaction.     

Dietary n‐3 LC‐PUFAs affect lipoprotein lipase (LPL) and fatty acid synthase (FAS) activities and mRNA expression during vitellogenesis and ovarian fatty acid composition of female silver pomfret (Pampus argenteus) broodstock

We studied the effects of dietary n‐3 LC‐PUFAs on the activities and mRNA expression levels of tissue lipoprotein lipase (LPL) and fatty acid synthase (FAS) during vitellogenesis and ovarian fatty acid composition in female silver pomfret broodstock. Broodstock were fed one of four experimental diets for 185 days: FO (100% fish oil), FSO (70% fish oil + 30% soybean oil), SFO (30% fish oil + 70% soybean oil) or SO (100% soybean oil). The results revealed that hepatic LPL and FAS and ovarian FAS activities and mRNA expression levels significantly increased at vitellogenesis and postvitellogenesis relative to previtellogenesis, with no significant differences between these two stages, except for hepatic LPL mRNA expression. Dietary n‐3 LC‐PUFAs decreased tissue FAS and increased LPL activities and mRNA expression levels. The ovarian concentrations of 20:4n‐6 (ARA), 20:5n‐3 (EPA), 22:6n‐3 (DHA) and n‐3 LC‐PUFAs were directly influenced by n‐3 LC‐PUFA levels. Total n‐3 LC‐PUFA concentrations in SO were 57% lower than those in FO, while 18:2n‐6 concentrations in SO were 4.7 ×  higher than those in FO. These results revealed that high dietary n‐3 LC‐PUFAs levels significantly affected tissue lipid metabolism in female silver pomfret broodstock during vitellogenesis by upregulating LPL and downregulating FAS.     

银鲳人工育苗技术研究

2005~2006年,在舟山海域银鲳繁殖季节(4~5月),随流刺网和张网捕鱼船出海,捕捞性腺成熟的银鲳进行人工授精,把胚胎运回岸上在孵化桶中继续孵化,得到初孵仔鱼并移入水泥池中进行培育。在水温19.0~24.0℃、盐度25.0~28.0的人工育苗条件下培育苗种。饵料为轮虫、卤虫无节幼体和配合饲料,孵化后3 d仔鱼开始开口摄食。银鲳初孵仔鱼~12日龄为仔鱼期,13~40日龄为稚鱼期,41日龄起转为幼鱼期。经50 d培育,获得20~27 mm叉长的银鲳幼鱼。育苗成活率为5%~14%。     

养殖与野生银鲳精巢发育形态学和组织学的初步比较

采用组织学与形态学等方法研究养殖与野生银鲳(Pampus argenteus)精巢结构、细胞形态、发育过程的异同点。结果表明:银鲳精巢结构为典型的小叶型结构,由精小叶、精小囊、小叶间质、小叶腔和输出管构成;生殖细胞可划分为5类;精巢发育与其他海水鱼类一样,可划分为6个时期。通过实验得知,养殖银鲳个体普遍小于野生银鲳的个体,且同等大小个体的养殖银鲳的精巢发育也不如野生银鲳精巢饱满,推测可能由于营养和环境温度的差异所造成。     

渤海银鲳的营养级及摄食习性

根据2017年9—11月在渤海进行的3次定点底拖网调查采集的216个样品[包括120个银鲳(Pampus argenteus)样品, 51个饵料生物样品和45个比较研究鱼类样品],采用碳、氮稳定同位素技术测定了样品的稳定同位素比值。对银鲳各饵料种类的贡献比率进行了计算,探讨其摄食习性、营养级、生态位宽度和生态位重叠随叉长变化的特征。同时也通过对比研究验证了采用稳定同位素技术研究银鲳摄食生态的准确性。结果表明:(1)渤海银鲳的δ~(13)C值范围为-19.50‰～-14.85‰,平均值为-17.18‰,与叉长相关性不显著(r=-0.03,P=0.71);δ~(15)N值范围为11.55‰～14.77‰,平均值为13.30‰,与叉长相关性极显著,但相关强度是弱相关(r=0.26,P0.01)。(2)基于R语言的贝叶斯稳定同位素混合模型(SIAR)计算各饵料贡献率,表明渤海银鲳为杂食性,其主要饵料为底层虾类,其贡献率为11.52%～57.49%,平均贡献率为35.03%;其次是中国毛虾(Acetes chinensis),其贡献率为13.52%～42.82%,平均贡献率为27.87%。其他饵料的贡献率从高到低依次为日本枪乌贼(Loligo japonica)、浮游植物和浮游动物,其贡献率范围分别为6.41%～42.57%、0～21.33%和0～16.21%;平均贡献率分别为23.29%、8.08%和5.77%。(3)随叉长增加,银鲳的食物组成存在一定变化。生态位宽幅计算结果表明,渤海银鲳的营养生态位宽度随叉长增大存在先升高后下降的特征, 90～109 mm叉长组的生态位宽幅达到最大;但各叉长组营养生态位相似,生态位存在较多的重叠。(4)渤海银鲳的营养级范围为2.84～3.79,平均营养级为3.35;营养级随着叉长增大有升高的趋势。(5)MDS图分析得出银鲳与赤鼻棱鳀(Thryssa kammalensis)的δ~(13)C和δ~(15)N值相似性最高。本研究通过碳氮稳定同位素技术对银鲳的营养级和摄食习性有了较全面的了解,对构建渤海全程食物网,进而研究其动态变化具有重要的意义。     

银鲳繁殖生物学及人工繁育技术的研究进展

银鲳是我国主要的经济鱼种之一,开展银鲳繁殖生物学的研究和人工育苗对资源的合理开发利用及海水养殖品种的结构调整、提高养殖效益等具有重要意义。本文根据近年来国内外对银鲳生物学以及育苗等方面的研究内容,归纳了银鲳繁殖生物学及人工繁育技术研究的现状,并提出了今后研究的重点。     

银鲳卵黄发生期间组织中抗氧化水平的变化及饲料n-3 LC-PUFA对其的影响

研究了银鲳(Papus argenteus)肝及卵巢组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性、总抗氧化能力(T-AOC)及丙二醛(MDA)含量在整个卵黄发生过程中的变化情况,并分析了饲料n-3 LC-PUFA对卵黄发生期间组织中抗氧化水平的影响。分别以100%鱼油(FO组)、70%鱼油和30%大豆油(FSO组)、30%鱼油和70%大豆油(SFO组)、100%大豆油(SO组)为脂肪源,配制了4组等氮、等能及等脂的试验饲料。以1年龄雌性银鲳为试验对象,每组饲料设3重复,试验周期185 d。研究结果表明,肝与卵巢组织SOD、CAT活性、T-AOC水平及MDA含量在卵黄发生过程中均呈现逐渐升高的趋势,且卵黄发生后期各指标水平均显著高于卵黄发生前期(P0.05)。肝SOD(除SO饲料组外)、CAT活性、T-AOC水平及MDA含量在卵黄发生中期与前期之间未表现出显著性差异(P0.05),而卵黄发生中期FO与FSO饲料组卵巢SOD、CAT活性及T-AOC水平则均显著高于卵黄发生前期(P0.05)。FSO饲料组肝与卵巢SOD、CAT活性在卵黄发生过程中均为最高值,且在卵黄发生中、后期均显著高于SO饲料组(P0.05),但与FO饲料组无显著性差异(P0.05)。各饲料组间肝与卵巢T-AOC水平在卵黄发生前期均未表现出显著性差异(P0.05),而在卵黄发生后期,FO与FSO饲料组肝与卵巢T-AOC水平均显著高于SO饲料组(P0.05),但FO与FSO饲料组间无显著性差异(P0.05)。肝与卵巢中MDA含量随着饲料n-3 LC-PUFA含量的升高而呈现出升高趋势,且这种升高趋势在肝组织中表现更为明显,卵巢组织MDA含量在卵黄发生中、后期仅FO饲料组表现出显著性升高趋势(P0.05),其他各饲料组在卵黄发生各期均未表现出显著性差异(P0.05)。统计分析表明,银鲳卵黄发生过程中组织中抗氧化水平逐渐升高,适宜的饲料n-3 LC-PUFA含量(4.01%,FSO饲料组)可明显改善银鲳卵黄发生中期与后期组织中的抗氧化水平。双因素方差分析结果表明,试验饲料与卵黄发生时期对银鲳组织抗氧化水平均具有极显著性影响(P0.01),且两者对肝T-AOC水平与MDA含量存在显著性的交互作用(P0.05)。     

Changes in the gut microbiome of the Chinese mitten crab (Eriocheir sinensis) in response to White spot syndrome virus (WSSV) infection

Intestinal microorganisms play important roles in maintaining host health, but their functions in aquatic animal hosts have yet to be fully elucidated. The Chinese mitten crab, Eriocheir sinensis, is one such example. We attempted to identify the shift of gut microbiota that occurred in response to infection of white spot syndrome virus (WSSV), an emerging viral pathogen in the crab aquaculture industry. The microbiota may exert some control over aspects of the viral pathogenesis. We investigated the changes in composition and structure of the crab gut microbiome during various WSSV infection stages of 6 h post‐infection (hpi) and 48 hpi, using a 16S rRNA approach on the MiSeq Illumina sequencing platform. Four phyla (Firmicutes, Proteobacteria, Tenericutes and Bacteroidetes) were most dominant in the gut of E. sinensis regardless of the WSSV infection stages. However, further analysis revealed that over 12 bacterial phyla, 44 orders and 68 families were significantly different in abundance at various states of WSSV infection. Several intriguing aspects of E. sinensis gut bacteria that had not been previously reported were also uncovered, such as class Mollicutes was dominant here, but absent in crabs from Yangtze River estuary and Chongming Islands. Overall, this study provided the first evidence that changes in gut microbiome were closely associated with the severity of WSSV infection and that indicator taxa could be used to evaluate the crab health status.     

银鲳亲鱼不同组织的氨基酸及其随性腺发育的变化

测定了海捕银鲳亲鱼肌肉,肝脏和性腺组织的氨基酸,并分析了不同性腺发育阶段的氨基酸变化。结果表明,雄性V期亲鱼精巢中的牛磺酸含量最高（27.8mg/g）,显著高于肌肉和肝脏组织,而雄性V期亲鱼氨基酸总量在肌肉中最高（631.4 mg/g）,其次是精巢（544.8 mg/g）和肝脏（468.0 mg/g）组织。雌性亲鱼肝脏中的牛磺酸含量（13.7 mg/g）显著高于卵巢和肌肉组织。在卵巢从III期发育到V期过程中,雌性亲鱼肌肉和肝脏中的氨基酸总量在V期下降显著,而卵巢氨基酸总量维持稳定。在总氨基酸的组成上,肌肉中含量高的氨基酸为Glu,Lys, Asp,Leu和Arg;肝脏中含量高的为Glu,Lys, Asp,Val和Leu;精巢中含量高为Glu,Asp, Lys, Arg和Val;卵巢含量高中为Glu,Lys,Leu,Val和Asp。性别和性腺发育阶段对亲鱼肌肉总氨基酸组成无影响。游离氨基酸含量在III 、IV和 V期卵巢中的含量分别为17.7 mg/g ,41.5 mg/g和29.6 mg/g,且其组成随性腺发育阶段的不同而有显著差异。     

不同饲料对银鲳幼鱼增重率、肝脏脂酶及抗氧化酶活性的影响

利用营养学与生物化学的方法,研究分析了不同饲料对银鲳幼鱼增重率、饲料系数、肝脏脂酶及抗氧化酶活性的影响。试验共设4组不同饲料,依次为饲料1(新鲜鱼肉糜)、饲料2(新鲜鱼肉糜+饲料)、饲料3(新鲜鱼肉糜+饲料+蛏子肉糜)和饲料4(新鲜鱼肉糜+饲料+蛏子肉糜+桡足类)。试验用银鲳幼鱼的平均体重为(4.80±0.11)g,每组饲料设3重复,试验周期为9周。研究结果显示,不同饲料可显著影响银鲳的增重率,各饲料组中以饲料1组的增重率最低,并显著低于其它各饲料组;饲料4组的增重率最高,并显著高于饲料2、3组的增重率(P<0.05)。饲料系数以饲料1组最高,且显著高于其它3组饲料组;饲料2、3、4组饲料系数间并无显著性差异(P>0.05)。饲料1组肝脂酶与总脂酶活性均显著低于其它3组饲料组(P<0.05),但饲料2、3、4组间肝脏脂蛋白脂酶、肝脂酶和总脂酶活性均未有显著性差异(P>0.05)。各组间肝脏超氧化物歧化酶(SOD)与谷胱甘肽过氧化物酶(GSH-PX)活性均未有显著性差异(P>0.05),但均以饲料1组最低、饲料4组最高;饲料1、2、3组间肝脏过氧化氢酶(CAT)活性未有显著性差异(P>0.05),但饲料4组CAT活性显著高于饲料1组的CAT活性(P<0.05)。分析结果表明,单纯利用鱼肉糜作为饲料不利于银鲳的生长;饲料中添加桡足类不但有助于促进银鲳的生长,也可提高其抗氧化能力。     

银鲳4个地理种群遗传多样性的初步研究

采用随机扩增多态DNA(RAPD)技术对取自海南(HN)、浙江(ZJ)、江苏(JS)、河北(HB)等近海海域的4个地理群体银鲳进行遗传多样性分析。从20个随机引物中筛选出10个,利用POPGEN Version 1.31软件对多态位点比例和遗传距离进行统计分析。共检测出总位点数56个,其中多态位点有39个,多态位点比例为69.64%。4个海域银鲳群体的Shannon多样性指数分别为0.123 2~0.158 7,Ne i基因多样性指数分别为0.077 6~0.100 4。JS群体与HN群体的遗传距离最远,为0.321 6;JS群体与HB群体的遗传距离最近,为0.231 6。结果表明,RAPD技术具有较高的灵敏性和多态性,是分析评估银鲳遗传多样性较为适宜的分子标记之一;JS群体保持着最高的遗传多样性,而HN群体多态性比例最低、ZJ群体Shannon多样性指数最低,应采取一些有效的保护措施,以避免HN群体遗传多样性的进一步丧失。     

饲料组成对银鲳幼鱼生长率及肌肉氨基酸、脂肪酸组成的影响

研究分析了饲料组成对银鲳(Pampus argenteus)幼鱼特定生长率(SGR)及肌肉氨基酸与脂肪酸组成的影响。实验共设4组不同的饲料组成,依次为饲料A(鱼肉糜)、饲料B(鱼肉糜+配合饲料)、饲料C(鱼肉糜+配合饲料+蛏子肉糜)和饲料D(鱼肉糜+配合饲料+蛏子肉糜+桡足类)。实验用银鲳幼鱼的平均体重为4.80±0.11 g,每组饲料设3重复,实验周期为9周。研究结果显示,不同饲料组成可显著影响银鲳的特定生长率,饲料A组的特定生长率最低,并显著低于其它各饲料组;饲料D组的特定生长率最高,且显著高于饲料B、C组的特定生长率(P<0.05);但饲料B、C组间银鲳特定生长率无显著性差异(P>0.05)。银鲳肌肉氨基酸与脂肪酸的分析结果显示,4组饲料组成对银鲳肌肉氨基酸的组成及含量并无显著性影响(P>0.05),但可显著影响肌肉脂肪酸的组成及含量(P<0.05)。饲料D组的多不饱和脂肪酸(PUFA)、高度不饱和脂肪酸(HUFA)及n-3HUFA含量均分别显著高于饲料A、B和C组(P<0.05),饲料B和C组的PUFA、HUFA及n-3HUFA均分别显著高于饲料A组(P<0.05),但饲料B、C组间并无显著性差异(P>0.05)。综合分析得出,丰富的饲料组成以及饲料中较高的HUFA含量均有利于银鲳幼鱼的生长。     

舟山渔场银鲳人工授精及孵化

2005-2008年,在舟山海域银鲳(Pampus argenteus)繁殖季节(4-5月),随流刺网或张网捕鱼船出海,捕捞性腺成熟的银鲳,进行人工授精和孵化.人工授精试验采用干法、湿法和半干法,比较受精率和孵化率.通过4年连续测量银鲳成熟卵的卵径、油球径等形态指标,对卵子成熟度进行判别,在水温16.0～18.5 ℃、盐度28.0±0.5的条件下进行孵化.结果表明,以干法受精后间隔3～5 min水洗和半干法受精的方法受精率最高,受精率达18.50%～33.50%,最高达40%;孵化率达到43.83%～51.00%,最高达66%.银鲳成熟卵子的卵径为(1.368±0.082)mm,油球径为(0.550±0.031)mm,油球1个.对影响海捕银鲳亲体受精率和孵化率的环境条件也进行了讨论.     

Formulated diet alters gut microbiota compositions in marine fish Nibea coibor and Nibea diacanthus

Nibea, an economical marine fish, is generally fed on trash fish (the low‐value fish), which can cause high feed costs and waste pollutions in high‐density aquaculture. To assess the effect of formulated diet on the gut microbiota in Nibea coibor and Nibea diacanthus, denaturing gradient gel electrophoresis, clone libraries analysis and Illumina sequencing of the 16S ribosomal RNA gene were used in this study. Two Nibea fishes were both dominated by Gammaproteobacteria (especially Photobacterium) and shared a set of gut microbiota, including Bacilli, Mollicutes, Alphaproteobacteria and Fusobacteriia. Statistical analyses revealed that formulated diet led to lower feed conversion ratio (p < 0.001), lower abundance of Vibrio (p = 0.040) and infectious diseases pathways (p = 0.001), higher abundance of polysaccharide‐degrading bacterium Cellvibrio (p = 0.006) in two Nibea species, with higher weight gain rate (p = 0.023) and microbial diversity (Shannon, p = 0.049 and Simpson, p = 0.044) and more carbohydrate metabolism (p = 0.020) observed in N. coibor. The distribution and correlation network of 17 potential short‐chain fatty acid producing bacteria were obtained and visualized in all treatment groups. The results reveal that formulated diet has beneficial effects on the gut microbial ecology in two Nibea fishes, which suggests the possibility of replacing trash fish diet with formulated diet in Nibea aquaculture.     

Scuticociliatosis-associated mortalities and histopathology of natural infection in cultured silver pomfret (Pampus argenteus Euphrasen) in Kuwait

Sub-adults of silver pomfret (Pampus argenteus), produced and reared in the mariculture experimentation facilities of Mariculture and Fisheries Department of Kuwait Institute for Scientific Research (KISR), suffered 55–70% mortalities due to scuticociliatosis by Uronema sp. The parasitic infestation was noticed during April–May 2005. Affected fish showed varying levels of tissue damage including severe epidermal and dermal necrotic lesions. The disease occurred with the raise in water temperature from 20 to 22 °C during April. Loss of scales, appearance of bleached spots that coalesced to form brownish patches, haemorrhagic and severe dermal necrotic lesions were the major clinico-pathological manifestations. The parasite was found abundantly in the blood, peritoneal fluid and the cerebrospinal fluid, the skin and the gill wet mounts. Extensive fouling, necrotic degeneration of the gill epithelium and deep dermal necrosis resulted in mortality of the infected fish. The parasite was noticed in the lumen of the collecting ducts of the kidney and the alimentary canal. The parasite was also seen distributed extensively in the entire brain causing widespread nerve necrosis. Earliest separation of the clinically normal fish from the affected fish resulted in significantly higher survival. The investigations are of significant importance in view of the mariculture potentials of the fish especially after the success of captive spawning and larval rearing achieved by the KISR.     

Assessment of the bacterial community diversity associated with the queen conch Strombus gigas (Linnaeus, 1758) from the Caribbean coast of Colombia using denaturing gradient gel electrophoresis and culturing

The biotic diversity of Strombus gigas has not been thoroughly studied despite the status of the queen conch as an important ecological resource. The bacteria associated with the conch influence their host in several ways, including through the metabolism of nutrients, protection against invasive bacteria and the regulation of the physical conditions. In this study, conventional microbiological methods and molecular tools such as denaturing gradient gel electrophoresis (DGGE) were used to assess the composition of the bacterial communities associated with the queen conch (S. gigas) in wild and captive habitats in Colombia. A genetic analysis of the bacterial communities revealed a high level of diversity based on the large number of bands detected using DGGE. In addition, differences in bacterial community structure were found between the conchs in captivity and the wild populations. The dominant phylogenetic affiliations of the bacteria, as determined using 16S rRNA gene sequencing, were grouped into four classes, namely, Betaproteobacteria (16%), Gammaproteobacteria (70%), Firmicutes (7%) and Actinobacteria (2%). These groups are related to host defence processes and the decomposition of organic matter. The 16S rDNA sequence analysis of the cultured bacteria and the resulting DGGE profiles are useful tools for characterizing the diversity of the bacteria associated with the analyzed conchs.     

Characterization of the bacterial community in different parts of the gut of sea cucumber (Apostichopus Japonicus) and its variation during gut regeneration

Bacterial community plays an important role in keeping the health status of the host. A study on the characteristics of gut bacterial community of sea cucumber (Apostichopus japonicus) not only helps improve the current aquaculture model, but promotes healthy and rapid development of the aquaculture industry as well. Therefore, taking pond‐cultured sea cucumber (A. japonicus) as the studying object, the metagenomic and 16S rRNA sequencing technology were used in this study to explore the characteristics of bacterial community in different parts of the gut of sea cucumber, as well as during gut regeneration after evisceration. The results showed that the compositions of bacterial community are different in varying parts of the gut of sea cucumber (A. japonicus). Specifically, bacterial community in the midgut and hindgut are highly similar, showing significantly diversified bacterial species compared to the foregut. GO annotation indicated that the foregut is associated with richer catalytic activity and binding than the midgut and the hindgut. According to the KEGG annotation, metabolism‐related genes are mainly concentrated in the foregut, while genes related to signal transduction and the immune system are mostly annotated in the midgut and hindgut. During the gut regeneration stage, the structure of bacterial community varied greatly in different stage of the regeneration stage, with significant differences between the earlier and later stage. The dominant bacteria in the earlier stage is Rubritalea, and that in the later stage is Arcobacter. Besides, there were Loktanella, Thalassobacter and Phaeobacter in the gut throughout the entire regeneration stage. Cupriavidus, Hellea, HTCC2207, Methylophaga, Methylotenera, Stenotrophomonas and Tenacibaculum were only present in the earlier stage, and gradually disappeared in the later stage due to improving gut functions. The abundance and diversity of bacteria in the gut were higher in the earlier regeneration stage than that in the later stage, with a peak between the 15th and 25th day of the regeneration stage. At 45th day, the abundance and diversity became stable.     

Short‐term starvation in silver pomfret (Pampus argenteus): molecular effects on lipid mobilization and utilization

To investigate the effects of short‐term starvation on lipid metabolism, juvenile silver pomfret (Pampus argenteus) with an initial weight of 18.1 ± 1.53 g were starved for 6 days. Fish were sampled on days 0, 2, 4 and 6 of starvation (S0, S2, S4 and S6, respectively) and then analysed. The results showed that short‐term starvation induced a significant decrease in visceral index, hepatosomatic index. The crude lipid content was also significantly decreased by 42.22% and 82.96% on S2 and S6 respectively. In addition, short‐term starvation significantly decreased the plasma triacylglycerol, non‐esterified fatty acid and low‐density lipoprotein cholesterol. Moreover, short‐term starvation significantly increased the expressions of hormone‐sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) at the mRNA and protein levels in the muscle and the ATGL expression at the protein level in the liver. The expressions of fatty acid translocase (CD36) and plasma membrane fatty acid‐binding protein (FABPpm) at the protein level in the muscle were significantly increased by short‐term starvation, while the expressions of fatty acid transport protein 1 (FATP1), FABPpm and lipoprotein lipase (LPL) at the protein level in the liver were significantly increased by short‐term starvation. Furthermore, the expressions of peroxisome proliferator activated receptor (PPAR) α and PPARγ at the mRNA and protein levels in the muscle were significantly elevated by short‐term starvation. These findings suggested that short‐term starvation increased lipid mobilization and utilization possibly through activation of lipolysis‐related genes (HSL and ATGL), lipid uptake‐related genes (LPL, CD36, FATP1 and FABPpm) and PPARs.     

Development of hatchery technology for the silver pomfret Pampus argenteus (Euphrasen): effect of microalgal species on larval survival

The silver pomfret Pampus argenteus (Euphrasen) is a new candidate for aquaculture and there is not much information available on its larval rearing. Investigations carried out using microalgae alone in the culture system for the initial feeding of the silver pomfret larvae showed that Chlorella, Isochrysis and Nannochloropsis without rotifers are not conducive to the survival of newly hatched larvae. At 6 days after hatching (DAH), a maximum survival of 3% (1.8 ± 1.69%) was observed with Isochrysis followed by Nannochloropsis (0.35 ± 0.21%) and Chlorella (0.25 ± 0.21%). All control larvae died at 6 DAH without microalgae. Further investigations using the above microalgae with rotifers and a mixture of these same microalgae with rotifers showed that significantly higher (P < 0.05) survival could be achieved in the mixture of microalgae with rotifers in the culture system. At 12 DAH, the larval survival was 9.73 ± 1.39% in mixed species of algae compared with that of Isochrysis (6.93 ± 1.86%), Nannochloropsis (6.83 ± 0.61%), Chlorella (5.93 ± 2.76%) and seawater without microalgae or the control (0.73 ± 0.31%). The first incidence of feeding on rotifers at 4 DAH was significantly higher (P < 0.05) in all treatments with microalgae than that of the control. The incidence of feeding in mixed species of algae at 4 DAH (60.0 ± 0.00%) and in Isochrysis (55.0 ± 35.36%) was significantly higher (P < 0.05) than that of Chlorella (40.0 ± 0.00%) and the control (25.0 ± 7.07%). Prey consumption of individual larvae increased significantly (P < 0.01) at 8 DAH compared with that at 4 DAH. During this period, predation on rotifers by larvae was significantly higher (P < 0.05) in mixed species of algae (12.85 ± 5.73 rotifers larva^?1) than that of the control (6.75 ± 1.20 rotifers larva^?1). The fatty acid composition of rotifers used during this investigation shows that significantly higher (P < 0.05) ω3 HUFA was present in rotifers treated with mixed algae plus commercial enrichment media ‘Super Selco’ and ‘DHA Protein Selco’. Rearing of silver pomfret larvae up to the juvenile stage using mixed species of microalgae in the hatchery has been discussed. During 38 days of the larval rearing period, it was possible to achieve 3.6–4.2% larval survival with a mean of 3.9 ± 0.42%, which was considerably higher than in previous attempts (survival up to 1.5%).