Edwardsiellosis in farmed turbot,Scophthalmus maximus (L.), associated with an unusual variant of Edwardsiella tarda: a clinical,aetiological and histopathological study

During 2005 and 2010, a survey of edwardsiellosis on eight turbot, Scophthalmus maximus (L.), farms was conducted in China. This report presents the detailed results of the study on this disease. Diseased turbot displayed two distinct types of gross signs: black discoloration of the dorsal skin on the posterior portion of the body; and red cutaneous foci on the ventral side. Internally, the most pronounced clinical signs in all fish examined were enlarged kidneys. The causal agent of the disease was finally proved to be one species of bacterium that was identified as Edwardsiella tarda by physiological and biochemical tests, API 32E and 16S ribosomal RNA sequence analysis. It is noteworthy that unlike the commonly described E. tarda strains, the isolates in this study were non‐motile strains without flagella. A histopathological study revealed that E. tarda infection was systemic in turbot and that kidney showed the most significant pathological changes, including acute focal necrosis, an influx of macrophages and formation of granuloma. The most common histopathological characteristics of this disease are the proliferation of macrophage in various organs and formation of granuloma. In addition, this article also gave background information on the disease and presented the results of virulence tests with the E. tarda strain identified in this study.     

日本米虾胚胎发育及离体孵化

本研究采用自制离体孵化装置,对日本米虾(Caridina japonica)不同发育期胚胎进行离体孵化研究,结果显示,水温为25.5℃时,日本米虾受精卵孵化大约需要25 d,发育积温为637.5℃。胚胎发育历经受精卵、卵裂期、囊胚期、原肠胚期、前无节幼体期、后无幼体期、前溞状幼体期和膜内溞状幼体期8个时期。各期离体胚胎均能孵化出幼体,膜内溞状幼体期离体胚胎孵化率最高,为(80.7±2.4)%,非离体孵化的对照组为(79.1±4.9)%,二者差异不显著;卵裂期离体胚胎孵化率最低,为(28.2±2.6)%,与对照组差异显著。各组离体胚胎所孵化出的Ⅰ期(ZⅠ)和Ⅱ期溞状幼体(ZⅡ)的变态率无显著差异。温度对日本米虾前溞状幼体期胚胎离体孵化影响显著,在15.0℃~32.5℃范围内,随水温升高孵化时间逐渐缩短,15.0℃时,前溞状幼体离体孵化时间为(436.8±124.8) h,32.5℃时缩短至(228.0±88.8) h,但温度高于29.0℃时,孵化出的幼体变态率开始下降。本研究可为日本米虾繁殖生物学及甲壳动物胚胎离体孵化技术研究提供参考。     

海带孢子体光合活性对不同温度和光照的响应

为了从生理生态学角度解答温度和光照对海带孢子体生长过程的影响,探索海带孢子体对温度和光环境的生理响应机制,实验在测定养殖海域海带孢子体生长参数的基础上,设定了6、10、14和18°C 4个水温梯度的海带孢子体暂养实验,以及它们在0、25、70、133、230、317、421、582、786μmol photons/(m2·s) 9个光合有效辐射(PAR)梯度下的光合活性荧光参数测定。结果显示:①在6°C水温条件下,海带孢子体荧光参数Fv/Fm和Fv/F0最大,分别为0.71和2.40;在18°C水温条件下,其Fv/Fm和Fv/F0最小,分别为0.65和1.85;②暂养海带孢子体的光化学淬灭(qP)和非光化学淬灭(qN或NPQ)在18°C水温条件下达到最大,分别为0.92和3.29;③海带孢子体的快速光曲线随着光合有效辐射(PAR)的增强呈现先上升后下降的趋势;④海域养殖海带孢子体的最大叶长增长速率、叶宽增长速率和干重增重率分别为1.34 cm/d、0.33 cm/d和1.01 g/d。研究表明,海带孢子体干重生长率变化与不同水温条件下的快速光曲线变化一致,高温抑制了海带孢子体光合效率;...     

Dietary lysine requirement of juvenile Protonibea diacanthus

An 8‐week experiment was conducted to determine the optimal dietary lysine requirement for juvenile Protonibea diacanthus. Six isonitrogenous and isolipidic diets were formulated to contain levels of 10.8 (L10.8), 18.2 (L18.2), 26.1 (L26.1), 33.9 (L33.9), 40.7 (L40.7) and 48.6 g/kg (L48.6) of diets and were fed to the juvenile Protonibea diacanthus, respectively. The results indicated that weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and final weight (FW) increased as the dietary lysine level increased from 10.8 to 26.1 g/kg and then decreased as the dietary lysine levels further increased (p < .05). The lowest feed conversion ratio (FCR) was found when dietary lysine level was 26.1 g/kg. Analysis of specific growth rate by two slope broken‐line model indicated that the estimated optimal dietary levels of lysine for juvenile Protonibea diacanthus was 23.06 g/kg (51.24 g/kg dietary protein).     

Effects of alternative dietary lipid sources on growth performance,health status and fillet fatty acid composition of hybrid sturgeon (Acipenser baeri Brandt ♀ × Acipenser schrenckii Brandt ♂)

An 8‐week trial was conducted to determine the effects of total replacement of 12.9% fish oil (FO) with soybean oil (SBO), peanut oil (PNO), sunflower seed oil (SFSO), corn oil (CO) and canola oil (CNO) on growth performance, health status and fillet fatty acid composition of hybrid sturgeon (194.28 ± 0.14 g). Compared to the FO group, dietary SBO decreased growth performance (p < .05), increased serum glucose and hepatic lipid content (p < .05). No obvious adverse effects on growth performance and health status were observed in PNO, SFSO and CO groups (p > 0.05). The fish fed with CNO had increased growth performance (p < .05), reduced serum ALT, AST, LDL‐C (p < .05) and enhanced serum GSH‐Px, T‐AOC, and LZM, MPO, C4 (p < .05). The contents of C18:1n9, C18:2n6, and ∑n‐3 PUFA and ∑n‐6 PUFA in fillets showed a positive linear correlation with the diets (p < .05). In summary, PNO, SFSO and CO are probable alternative lipid sources to fully replace FO. Hybrid sturgeon prefers to use CNO as a lipid source with improved growth performance and health status. The fillet fatty acid composition mirrors the dietary fatty acid composition.     

Fe~(3+)对鼠尾藻光合呼吸作用和生化组成的影响

研究了不同浓度Fe~(3+)对鼠尾藻光合作用、呼吸作用和体内不同生化组成的影响。结果表明,不同的Fe~(3+)浓度对鼠尾藻真光合速率和呼吸速率均有显著的影响,在0.04 mg/L的Fe~(3+)浓度下鼠尾藻的光合作用能力达到最强,而0.06 mg/L的Fe~(3+)浓度下鼠尾藻的呼吸作用达到最高;不同Fe~(3+)浓度下,鼠尾藻体内叶绿素a浓度和类胡萝卜素浓度变化显著,可溶性蛋白含量和可溶性糖含量变化不显著。     

Effect of heat stress and recovery on viability,oxidative damage,and heat shock protein expression in hepatic cells of grass carp (Ctenopharyngodon idellus)

In this study, we investigated the effects of hyperthermia and recovery on cell viability, lactate dehydrogenase (LDH) activity, superoxide dismutase (SOD) activity, malondialdehyde (MDA), total antioxidant capacity (T-AOC), and heat shock protein (HSP60, 70, and 90) mRNA expression in the hepatic cells of the grass carp, Ctenopharyngodon idellus. Triplicate groups of cultured cells were exposed to 30, 32, or 34 °C for 0.5 h and then immediately incubated at 27 °C in 5 % CO₂ for 6, 12, 24, or 48 h. Hyperthermia stress greatly reduced cell viability and increased LDH release. Cell damage declined after recovery. Hyperthermia stress increased the lipid peroxide levels and reduced the antioxidant capacity (e.g., reduced SOD and T-AOC) of the cells. However, oxidative damage declined as the recovery period increased, and the levels of MDA, SOD, and T-AOC were restored. After cells were exposed to 32 °C, the expression of HSP60 after recovery for 1, 2, and 4 h (P < 0.05), the expression of HSP70 after recovery for 0.5 and 1 h (P < 0.01), and the expression of HSP90 throughout recovery were significantly higher (P < 0.01) than the prestress levels. During the recovery period, the variations in HSP gene expression reflected the transition period from a state of cellular growth to one of the cellular repairs. In conclusion, hyperthermia depresses cell viability, induces oxidative damage, and increases HSP expression, which plays an important role during hyperthermic stress in grass carp hepatic cells.     

Effect of enrofloxacin and emodin on heat-shock proteins’ expression in hepatic cells of grass carp (Ctenopharyngodon idellus)

The aim of the present study was to compare the expression pattern of heat-shock protein 60 (HSP60), 70 (HSP70), and 90 (HSP90) mRNA in hepatic cells of grass carp exposed to enrofloxacin and emodin concentrations. The expression pattern of different genes encoding heat-shock proteins in hepatic cells of grass carp was exposed to graded levels of enrofloxacin (12.5, 25, 50, 100, and 200 μg/ml) or emodin (0.04, 0.2, 1, 5, and 25 μg/ml) for 24 h and were investigated by real-time quantitative PCR. When cells were exposed to up 50 μg/ml enrofloxacin, both HSP60 and HSP70 mRNA levels firstly were increased and thereafter significantly dropped at high concentrations (P < 0.05), while HSP90 decreased with increasing enrofloxacin concentration. Besides, HSP60 and HSP70 expressions were significantly inhibited in the high-concentration groups. In addition, the HSP90 mRNA levels in the treatment exposed to 100 and 200 μg/ml enrofloxacin were significantly lower than those of the control group (P < 0.05). Furthermore, when cells were exposed to graded levels of emodin, HSPs (HSP60, 70, and 90) mRNA levels significantly increased in the groups exposed to 5 and 25 μg/ml of emodin. The different expression pattern of HSPs implied that enrofloxacin could inhibit the expression levels of HSPs, while optimal level of emodin could trigger higher expression levels of HSPs in hepatic cell of grass carp to protect against further damage.     

珍味贝丝的研制报告

本试验利用扇贝加工时大量废弃的裙边,制作调味焙烤品珍味贝丝,经1％冰醋酸软化处理15s,150℃焙烤6min,较好地解决了艮韧问题,并对工艺路线和主要工艺参数进行了选择。制品档次较高,保质期达6个月以上。     

Dietary quercetin improved the growth,antioxidation, and flesh quality of grass carp (Ctenopharyngodon idella)

To investigate the effects of dietary quercetin on growth, antioxidation, and flesh quality of grass carp, Ctenopharyngodon idella, six diets were prepared with quercetin inclusion rates of 0 (control diet), 0.1, 0.2, 0.4, 0.6, and 0.8 g/kg. Grass carp with a body weight of 13.3 ± 0.1 g were fed with one of the six diets for 60 days. The weight gain (WG) showed a quadratic relationship with dietary quercetin levels; the supplementation of 0.4 g/kg quercetin significantly improved WG (+4.73%) and decreased feed conversion ratio (?0.06) (p < .05) when compared to those of the control group. The intestinal fat ratio was reduced by the addition of 0.2 or 0.4 g/kg of quercetin (p < .05), and serum activities of alkaline phosphatase and superoxide dismutase were increased by the addition of 0.4 and 0.6 g/kg of quercetin (p < .05). The inclusion of 0.2–0.6 g/kg of quercetin increased the contents of delicious amino acids and decreased the cooking loss of flesh (p < .05). Flesh collagen content was increased by the addition of 0.4–0.8 g/kg of quercetin (p < .05). In conclusion, dietary quercetin could improve the growth and enhance the antioxidation and flesh quality of grass carp, with the recommended supplemental level of quercetin was 0.37 g/kg.