Dietary arginine requirement of juvenile kuruma shrimp Marsupenaeus japonicus (Bate)

The requirements for essential amino acids by kuruma shrimp, Marsupenaeus japonicus (Bate) have not yet been determined using the dose–response method due to poor utilization of crystalline amino acids (CAA). In a previous study, we produced coated CAA that could be used to retard leaching losses. Therefore, to determine the arginine requirement of juvenile kuruma shrimp, a growth study was conducted using test diets containing six levels of coated arginine (from 1.20% to 3.19% of diet) for 42 days. Crystalline amino acids was supplemented to correspond to the amino acid pattern in the whole body protein of the kuruma shrimp except for arginine. To reduce leaching losses, CAA were coated with carboxymethylcellulose (CMC) and diets were further bound with CMC and k‐carrageenan. Test diets were fed to triplicate groups of juveniles (0.25±0.02 g) twice a day. Proximate composition and the amino acid composition of shrimp whole bodies were analysed at the end of the feeding trial. Percent body weight gain (WG), specific growth rate, feed intake, feed efficiency ratio and protein retention efficiency were significantly affected by the dietary arginine concentrations. Estimating the arginine requirement of kuruma shrimp using broken‐line analysis of percent WG resulted in a value of 2.66% of diet or 5.32% of protein. After correcting for leaching of arginine from the diets, the optimum dietary value of arginine for kuruma shrimp was a little lower than the estimated value.     

Effects of Na/K and Mg/Ca ratios in saline groundwaters on Na-K-ATPase activity, survival and growth of Marsupenaeus japonicus postlarvae

The effects of the Na⁺/K⁺ and Mg²⁺/Ca²⁺ ratios in saline groundwaters on Na⁺-K⁺-ATPase activity, survival and growth of Marsupenaeus japonicus postlarvae were investigated. The results indicate that the Na⁺-K⁺-ATPase activity, survival rate and weight gain of postlarvae were significantly affected by the Na⁺/K⁺ and Mg²⁺/Ca²⁺ ratios (P < 0.05). The Na⁺-K⁺-ATPase activity of postlarvae, in every treatment, changed corresponding to Na⁺/K⁺ and Mg²⁺/Ca²⁺ ratios, and came to a stable level after 24 h. There was a negative relation between Na⁺-K⁺-ATPase activity and Na⁺/K⁺ ratio, while there was a positive relation between Na⁺-K⁺-ATPase activity and Mg²⁺/Ca²⁺ ratio. Compared with seawater (the Na⁺/K⁺ and Mg²⁺/Ca²⁺ ratios are 27.8 and 4.64 respectively), the Na⁺-K⁺-ATPase activity of the Na⁺/K⁺ ratio 30 treatment showed no significant difference, while the Mg²⁺/Ca²⁺ ratio 4.5 treatment showed distinct difference. The survival rates and weight gain of postlarvae increased markedly when the suitable amount of K⁺ and Ca²⁺ was added to test water, and arrived at their maximum in the Na⁺/K⁺ ratio 20-30 or Mg²⁺/Ca²⁺ ratio 4.5 treatment, having no significant difference compared with normal seawater. Therefore, considering the Na⁺/K⁺, Mg²⁺/Ca²⁺ ratios and the absolute concentration of Mg²⁺, Ca²⁺ in the experimental saline groundwaters applied to Marsupenaeus japonicus farming, it should be modulated to around 30, 4.5 and 1312 mg/l, 291 mg/l, respectively.     

Assessment of requirement values for essential amino acids in the prawn, Marsupenaeus japonicus (Bate)

The requirements of juvenile prawn, Marsupenaeus japonicus (Bate), 0.79 g initial body weight, for essential amino acids (EAA) were evaluated based on the daily increase of each EAA in the whole body when the prawn was maintained on a diet with a high nutritive value (a casein‐squid protein‐based diet). The quantities of each EAA needed daily for growth and maintenance of prawn are conceived to correspond to the daily requirements of this prawn species for EAA. Therefore, these requirement values of respective EAA should be supplied from dietary proteins. To determine these values, protein and amino acids of the whole body of the prawn were quantified before and after feeding experiments, and the quantities of respective EAA needed to meet the requirements were estimated based on the EAA profile of the whole body protein of prawn. As a result, the contents of EAA in dietary proteins (%) needed to meet the requirements of the prawn for EAA were assessed to be: threonine (2.3), methionine (1.3), valine (2.4), isoleucine (2.3), leucine (3.4), phenylalanine (2.6), lysine (3.2), histidine (1.1), arginine (2.9) and tryptophan (0.6), respectively, when the prawn are fed 50% protein diet with 90% protein digestibility at a ration size of 2% (% of body weight).     

浙麦冬黑斑病病原菌的分离鉴定及淀粉酶产色链霉菌对其生物防治效果

黑斑病是浙江省慈溪市浙麦冬种植基地常发病害,传染速度快且严重影响麦冬的产量与品质。为了明确引起黑斑病的病原菌以便后续有效防治该病害,本文通过对染病组织培养、病原菌分离纯化和柯赫法则验证、形态学观察与基因序列分析比对（ITS、EF-1α、RPB2、Alt a 1、His 3、ATP）,最终鉴定出引起浙麦冬黑斑病的病原菌是链格孢菌Alternaria alternata。研究淀粉酶产色链霉菌Streptomycesdiastatochromogenes 1628代谢产物对黑斑病的防效结果表明,1628代谢产物对链格孢菌菌丝生长具有较强的抑制作用,其EC₅₀=0.764%（体积浓度）。田间防效结果表明7和14 d校正防效分别可达74.08%和65.28%,均高于阳性对照多菌灵。本研究明确了浙麦冬黑斑病病原菌的分类地位,并筛选到能有效抑制该病原菌的生防菌株淀粉酶产色链霉菌,为后续浙麦冬黑斑病的防治提供依据。     

SO_2胁迫对大叶黄杨和贴梗海棠膜脂过氧化及保护酶的影响

以贴梗海棠和大叶黄杨为试材,研究经SO2胁迫后,其生理生化的变化,结果表明,SO2处理使贴梗海棠和大叶黄杨O2-速率、MDA含量、细胞膜相对透性均增加,而且贴梗海棠的增加比率比大叶黄杨大,且随SO2质量浓度的增加,这3个指标的增加比率均呈升高趋势;经SO2处理后,贴梗海棠和大叶黄杨的SOD和POD活性均上升,抗性植物的升高比率大于敏感植物,随SO2质量浓度的增加,SOD和POD活性的增加比率升高,脱离熏气后,POD活性均经一个应激上升过程随后下降,且抗性植物大叶黄杨出现应激反应早于贴梗海棠;经SO2处理后,贴梗海棠和大叶黄杨的CAT活性下降,且随SO2质量浓度的增加下降比率增加。     

溴氰菊酯对日本对虾的急性毒性及积累试验研究

采用半静态换水补药的方法,开展溴氰菊酯对日本对虾的急性毒性及积累试验,并且记录下不同溴氰菊酯浓度下日本对虾的中毒症状。通过试验获得溴氰菊酯对日本对虾24h、48h、72h和96h的半致死浓度(LC50)值分别为0.00090mg/L、0.00050mg/L、0.00019mg/L、0.00012mg/L,96h安全质量浓度为0.046μg/L。通过药物积累试验表明在试验期间内,水体中溴氰菊酯浓度与受试生物体内溴氰菊酯的积累量成负相关。     

日本对虾人工选育种繁育试验

本文对虾人工育苗的各个阶段对抗病选育的日本对虾的人工繁育情况进行了试验。结果表明,抗病选育的日本对虾子3代可以正常产卵,产出的受精卵能正常孵化出无节幼体,并顺利发育到子虾。     

武明欣1，2王际英2李宝山2张德瑞3蔡胜昌1，2王世信2孙永智2张利民2?

本试验旨在研究酶制剂对刺参生长、体成分、免疫能力及氨氮胁迫下免疫酶活力和热休克蛋白70含量的影响。试验共配制粗蛋白质含量为20％的试验饲料5种,首先配制不含酶制剂的基础饲料作为对照,然后分别以0．04％木聚糖酶、0．10％纤维素酶、0．01％淀粉酶和0．15％复合酶（由0．04％木聚糖酶、0．10％纤维素酶和0．01％淀粉酶组成）等量替代基础饲料配方中的α－淀粉。每种饲料设3个重复,每个重复放养体重（4．02±0．04） g 的幼参40头。试验期为56 d。结果表明：1）木聚糖酶、纤维素酶、淀粉酶、复合酶组的增重率分别比对照组提高了17．38％（P＜0．05）、7．63％（P＜0．05）、1．88％（P＞0．05）和20．75％（P＜0．05）,特定生长率分别比对照组提高了0．25％／d（P＜0．05）、0．03％／d（P＜0．05）、0．01％／d（P＞0．05）、0．30％／d（P＜0．05）。2）饲料中添加木聚糖酶显著提高了刺参体壁粗蛋白质的含量（ P＜0．05）,添加纤维素酶、淀粉酶和复合酶显著提高了刺参体壁粗蛋白质、粗脂肪和粗灰分的含量（ P＜0．05）。3）饲料中添加木聚糖酶、纤维素酶和复合酶显著提高了体腔液中过氧化氢酶的活力（ P＜0．05）;添加淀粉酶显著提高了体腔液中溶菌酶、超氧化物歧化酶、过氧化氢酶活力（ P＜0．05）。4）在120 h氨氮胁迫过程中,各组体腔液中溶菌酶、超氧化物歧化酶、过氧化氢酶活力及热休克蛋白70含量基本呈先上升后下降趋势。除纤维素酶组外,其余加酶组体腔液中热休克蛋白70含量的最大值均高于对照组。综上,饲料中适量添加木聚糖酶、纤维素酶、淀粉酶或其复合酶均能显著促进刺参生长,改善体成分,提高免疫能力,木聚糖酶的促生长作用更明显,而淀粉酶的促免疫作用更明显。氨氮胁迫下,饲料中适量添加木聚糖酶、纤维素酶、淀粉酶或其复合酶均能使刺参更迅速和强烈地表现出免疫抵抗反应。