CD40 induces an antimicrobial response against the intracellular pathogen Streptococcus agalactiae in Nile tilapia,Oreochromis niloticus

Streptococcus agalactiae is a Gram‐positive facultative intracellular bacterium that leads to severe economic loss of tilapia worldwide. Previous studies demonstrated that CD40 contributes to host protection against intracellular injection. In this study, CD40 was characterized from Nile tilapia (Oreochromis niloticus), named OnCD40. Sequence analysis showed that open reading frame of OnCD40 was 933 bp, containing a single peptide, a transmembrane domain and four cysteine‐rich domains. The qRT‐PCR revealed that OnCD40 was expressed in all examined tissues with the most abundant ones in spleen and thymus. After S. agalactiae stimulation, the expression of OnCD40 was significantly induced in most of the detected organs. Moreover, OnCD40‐overexpressing fish elicited significant protection against subsequent S. agalactiae challenge; approximately 10000‐fold fewer bacteria were detected in spleen of OnCD40‐overexpressing fish in comparison with control fish. Thus, CD40 had protecting function in Nile tilapia against intracellular pathogens.     

Assessing the effects of line capture and barotrauma relief procedures on post-release survival of key tropical reef fish species in Australia using recreational tagging clubs

Abstract  Common coral trout, Plectropomus leopardus Lacepède, crimson snapper, Lutjanus erythropterus Bloch, saddletail snapper, Lutjanus malabaricus (Bloch & Schneider), red emperor, Lutjanus sebae (Cuvier), redthroat emperor, Lethrinus miniatus (Schneider) and grass emperor, Lethrinus laticaudis Alleyne & Macleay, were tagged to determine the effects of barotrauma relief procedures (weighted shot-line release and venting using a hollow needle) and other factors on survival. Release condition was the most significant factor affecting the subsequent recapture rate of all species. Capture depth was significant in all species apart from L. malabaricus and L. miniatus , the general trend being reduced recapture probability with increasing capture depth. Recapture rates of fish hooked in either the lip or mouth were generally significantly higher than for those hooked in the throat or gut. Statistically significant benefit from treating fish for barotrauma was found in only L. malabaricus , but the lack of any negative effects of treating fish indicated that the practices of venting and shot-lining should not be discouraged by fisheries managers for these species.     

Relative potencies of natural estrogens on vitellogenin and choriogenin levels in the Indian freshwater spotted snakehead, <Emphasis Type="Italic">Channa punctata</Emphasis>: in vivo and in vitro studies

The relative efficacies of three natural estrogens viz., estrone (E₁), estradiol-17β (E₂) and estriol (E₃) to induce synthesis of vitellogenin (Vg) and choriogenin (Chg) were assessed in primary hepatocyte cultures of the Indian freshwater spotted snakehead, Channa punctata. Hepatocytes were isolated from the spotted snakehead liver by a non-enzymatic protocol. Optimum culture conditions were standardized for ensuring their viability and functioning. Isolated hepatocytes were cultured for 48 h for monolayer formation and then exposed to various concentrations (0.001–10 μM) of the three estrogens. Competitive homologous ELISAs, developed and validated for spotted snakehead Vg and Chg were employed to determine the amounts of these two proteins secreted into the culture medium after 48 h of incubation. The results reveal that although all the three estrogens were effective in inducing the production of Vg and Chg in a dose-dependent manner, there were differences in their relative potencies. Of three estrogens, E₁ was the least potent and could induce synthesis of Vg and Chg only at a minimum concentration of 0.5 μM; whereas significant levels of both the proteins were quantified in culture medium by exposing the hepatocytes to E₂ or E₃ even at a concentration of 0.001 μM. All three estrogens were effective in inducing synthesis of Vg and Chg in vivo also. These results suggest the possibility of employing the above in vitro experimental design to monitor the presence of estrogens/estrogen-like chemicals in natural waters, which could interfere with the estrogen receptor system of fish. This study further points to the possibility of using Chg, in addition to Vg, as a parameter for screening various chemicals for their estrogenic activity.     

Haemolymph metabolic variables in relation to eyestalk ablation and gonad development of Pacific white shrimp Litopenaeus vannamei Boone

The present study analyses some biochemical variables in haemolymph proposed as predictive indicators of the maturation capability following eyestalk ablation. Haemolymph of captive females was obtained before and 8 days after eyestalk ablation, and levels of haemocyanin, total proteins, glucose, lactate, cholesterol, triacylglycerides and vitellogenin were determined. Biochemical variables were also analysed in the hepatopancreas at the end of the experiment. Females were grouped as immature (previtellogenic stage) and mature (vitellogenic and cortical stages) based on histological analysis done 8 days after eyestalk ablation. To analyse haemolymph variables before eyestalk ablation in relation to maturation capability, immature females were classified as those with a low maturation capability and mature females as those with a high maturation capability. Females of high maturation capability had significantly higher vitellogenin levels before eyestalk ablation than females of low maturation capability. No significant differences were found for the other biochemical variables. Vitellogenin was also higher in mature than in immature females at the end of the experiment. These results indicate that vitellogenin levels in haemolymph could be used as possible predictive criteria of maturation capability, possibly because they reflect the degree of ovarian development at the time of eyestalk ablation.     

卤虫虾片对水体pH值的影响

通过喂养中国对虾幼体试验，分别以卤虫虾片试验组和传统饵对照组进行。试验表明，在幼体成活率方面，前者稍优于后者，在养殖水体的最主要指标PH方面，二者差别不大。说明投喂卤虫虾片对中国对虾幼体的成活率和水质无良影响，用低值的卤虫虾片代替部分或全部高价的活体饵料是切实可行的，能够满足育苗需要。     

对虾皮下及造血组织坏死杆状病毒的精细结构、核酸、多肽及血清学研究

对纯化的对虾皮下及造血组织坏死杆状病毒（ＨＨＮＢＶ）进行了超微结构、紫外吸收、核酸类型及多肽ＳＤＳ－ＰＡＧＥ的研究。同时用单克隆抗体对ＨＨＮＢＶ的两分离株和ＭＢＶ进行了血清学比较研究。用ＴＭＶ作为内标定物测得病毒粒子大小为１５０ｎｍ×４５０ｎｍ，其衣壳为两个帽状物端夹１３圈螺旋对称的园柱体结构。病毒在２６０ｎｍ处吸光系数为０．１１７ｍｇ／ｍＬ／ＯＤ２６０。病毒核酸为双链ＤＮＡ，分子量大于３５×１０６ｄ。病毒囊膜有１２种主要多肽。病毒衣壳有两种主要多肽。从寿光（ＨＨＮＢＶ—９３７）和青岛（ＨＨＮＢＶ—９３８）分离到的病毒种在ＳＤＳ—ＰＡＧＥ和抗ＨＨＮＢＶ—９３７单抗ＥＬＩＳＡ反应上没有显著差异。ＨＨＮＢＶ与斑节对虾杆状病毒（ＭＢＶ）在抗原决定簇上存在差别。     

Probiotic microorganisms and antiviral plants reduce mortality and prevalence of WSSV in shrimp (Litopenaeus vannamei) cultured under laboratory conditions

The protective effect of a probiotic mixture (PM) and antiviral plants, against the white spot syndrome virus (WSSV) in Litopenaeus vannamei , was evaluated in three experiments. The PM was composed of four lactic acid bacteria (LAB) and one yeast strain. The plant mixture was composed of Ocimum sanctum and commercial antiviral plants (VPH^®, HSV^®). Shrimp in each experiment (weighing 2.7±0.7, 11.5±1.3, 11.70±2.5 g) were cultured in 120-L plastic tanks and fed twice a day with commercial feed plus additives (plants or bacteria and yeast). Animals were monitored for the occurrence of WSSV by single-step and nested PCR. The PM and powdered antiviral plants added to the commercial feed showed an increase in survival and a decrease in the prevalence of WSSV in shrimp. The results showed that both the PM and the powdered antiviral plants can provide protection for shrimp against WSSV.     

Evolutionary implications of two rainbow trout growth hormone genes

The primary structures of two rainbow trout growth hormone mRNAs (GH1 and GH2) have been deduced by direct sequencing of their respective cDNA clones and portions of the mRNA. Both GH1 and GH2 mRNA contain open reading frames comprised of 630 nucleotides and encode 210 amino acid residues of which 11 are variant. The translated regions of both mRNA are flanked by a short but rather conserved 5′-end, and a relatively long but highly diverged 3′-end. The differences at translated and 3′-untranslated regions suggest that the GH1 and GH2 mRNA originate from different loci. The GH1 and GH2 mRNA are likely transcribed from two distinct loci which were duplicated during tetraploidization of salmonid genome between 50 to 100 million years ago. The GH2 gene has been isolated and sequenced from a rainbow trout genomic library. This gene spans a region of approximately 4 kilobases. The trout GH gene is comprised of 6 exons and 5 introns, in contrast to 5 exons and 4 introns in mammals. The additional intron in the trout gene interrupts the translated regions that are analogous to the last exon of the mammalian counterpart. The alleged internally repeating sequences in mammalian GH, prolactin (Pr1) and placental lactogen (PL) are not observed in the predicted polypeptide sequence of trout GH. In addition, direct repeats that flank exons I, III and V of mammalian GH, Pr1 and PL genes are absent in trout gene. These findings indicate that the rainbow trout GH gene structure does not support the current hypothesis that internally repeated regions in GH, Pr1 and PL arose from a small primordial gene.     

Effects of glycinin on growth performance,immunity and antioxidant capacity in juvenile golden crucian carp,Cyprinus carpio × Carassius auratus

This study was designed to examine the effects of glycinin on growth, digestive ability, immune responses, antioxidant capacity and gene expression levels of golden crucian carp. Golden crucian carp were fed diets containing glycinin at 0, 30, 60, 90 and 120 g/kg, respectively, for 8 weeks. Body weight, weight gain percentage, specific growth rate and feed efficiency ratio were negatively related to the content of glycinin in diet. Activities of protease, acid phosphatase, alkaline phosphatase, lysozyme in hepatopancreas, and activities of catalase, glutathione peroxidase, superoxide dismutase, and total antioxidant capacity in the proximal intestine, mid intestine, distal intestine and hepatopancreas were negatively related to the content of glycinin in diet, whereas malondialdehyde in proximal intestine, mid intestine, distal intestine and hepatopancreas increased directly with the content of glycinin in diet. Furthermore, the relative expressions of TNF‐α and IL‐1β in proximal intestine, mid intestine and distal intestine increased directly with the content of glycinin in diet, whereas the relative expressions of TNF‐α and IL‐1β in hepatopancreas were negatively related to the content of glycinin in diets. The relative expressions of IL‐10 in proximal intestine, mid intestine, distal intestine and hepatopancreas all were negatively related to the content of glycinin in diets. In conclusion, reductions in growth, immunity and antioxidant capacity, intestine inflammation with dysfunction of digestive system occurred in golden crucian carp that fed a diet containing glycinin at 30 g/kg or higher after 8 weeks.