基于Hertz接触理论的黑水虻幼虫碰撞恢复系数测定

为建立黑水虻幼虫与收集、输送、分离等机械工作部件间发生碰撞时的碰撞模型，基于黑水虻幼虫生物特性，应用Hertz弹性碰撞理论推导了黑水虻幼虫碰撞过程动力学方程，结合运动学方程原理构建了黑水虻幼虫恢复系数的测定装置并进行了黑水虻幼虫恢复系数测定试验。试验针对第5龄期的黑水虻幼虫，采用L16(44×23)混合正交试验方案研究了碰撞材料、材料厚度、下落高度、碰撞角、跌落方向、含水率等因素对黑水虻幼虫恢复系数的影响，然后对碰撞材料、材料厚度、下落高度、碰撞角、跌落方向进行单因素试验，并获得了材料厚度、下落高度、碰撞角对恢复系数的影响规律与回归方程，且方程的决定系数均不小于0.9427。试验结果表明，影响黑水虻幼虫恢复系数的因素影响由大到小为：碰撞材料、下落高度、碰撞角、跌落方向、碰撞材料厚度、含水率，其中含水率对恢复系数影响不显著。单因素试验结果可得：黑水虻幼虫与Q235钢、铝合金、有机玻璃、橡胶等碰撞材料间的恢复系数依次降低，随下落高度的增大而逐渐减小，随材料厚度的增加而逐渐增大，恢复系数随碰撞角的增大而整体呈增大趋势，且横向跌落方向大于纵向跌落方向。该文研究结果可为黑水虻幼虫收集、输送、分离等机械相关工作部件优化设计提供参考依据。     

小麦山农4143抗黑胚病遗传分析及抗性遗传位点检测

 黑胚病是小麦生产的重要籽粒病害,麦根腐平脐蠕孢(Bipolaris sorokiniana)是黑胚病的主要致病菌。为分析小麦抗黑胚病遗传规律并检测抗性位点,本研究以抗黑胚病小麦品系山农4143与感病品系宛原白1号的F₇代重组自交系(RIL)群体为材料,于2018~2019年在3个试验点种植,采用“孢子液喷洒、套袋保湿”的方法进行接菌鉴定,用“主基因＋多基因混合遗传模型”进行遗传分析,并挑选极端抗、感自交系构建混池、结合小麦660K SNP芯片进行混合分组分析(BSA)。研究结果显示小麦品系山农4143对黑胚病抗性符合“4对主基因加性-上位性遗传模型”,主基因遗传力为0.88~0.95;通过BSA检测到黑胚病抗性位点36个,分别位于1A、2B(6)、2D(2)、3A、3B(2)、3D、4A(6)、4D、5A(4)、5B(6)、5D(3)、7A、7B和7D共14条染色体上,A、B、D染色组上分别为13、 15和8个,36个位点中有18个为抗黑胚病新鉴定位点。本研究结果为小麦抗黑胚病位点的精细定位和抗性育种中分子标记的开发奠定了基础。     

核桃细菌性黑斑病杀菌剂筛选及药效研究

本文以黄单胞杆菌Xanthomonas campestris pv.juglandis(Pierce Dowson)为供试菌株,选用不同浓度的13种杀菌剂进行室内毒力测定。结果表明:有10种药剂对该菌有一定的抑制效果,但只有5种杀菌剂能够产生明显的抑菌圈。其中,四霉素和链霉素的抑菌效果最强,最低抑菌浓度为0.165、3μg/mL,抑菌率为74.76%、69.23%,EC_(50)为12.764、35.318μg/mL。其他依次为乙蒜素、中生菌素和春雷霉素。选用这5种杀菌剂进行盆栽防治试验,四霉素和链霉素的平均防效达74.60%、71.69%,乙蒜素和中生菌素防效分别为65.98%、58.40%,春雷霉素防效最低为39.38%。其结果与室内基本一致。室内试验及盆栽试验结果表明四霉素、链霉素、乙蒜素、中生菌素和春雷霉素可作为防治核桃黑斑病的杀菌剂,其中四霉素为首选杀菌剂。     

5种药物对异育银鲫"中科3号"受精卵孵化的影响

在水温21~23℃,pH 6.2~6.5条件下,采用半静水试验法,按等对数间距设置药物质量浓度梯度,日换水50%,补充药物50%,24 h观察记录1次,比较美婷Ⅱ、霉灵、纳他霉素、杀毒矾和高锰酸钾5种药物对异育银鲫"中科3号"受精卵水霉抑制作用及孵化率的影响。试验结果显示,试验药物对受精卵水霉生长均有一定抑制作用,其抑霉率为美婷Ⅱ>霉灵>高锰酸钾、纳他霉素和杀毒矾,但杀毒矾对异育银鲫"中科3号"受精卵的毒副作用较大,显著降低了受精卵孵化率,不宜使用;美婷Ⅱ、霉灵、纳他霉素和高锰酸钾对异育银鲫"中科3号"受精卵的适宜使用质量浓度分别为4.90~6.50、1.97~3.87、1.50、2.50 mg/L,使用方法为长时间浸浴,可有效抑制受精卵孵化过程中水霉的生长,显著提高受精卵孵化率,适合在异育银鲫"中科3号"受精卵孵化过程中使用。     

Three SNPs within exons of INHA and ACVR2B genes are significantly associated with litter size in Dazu black goats

The aim of this study was to analyse the association between single-nucleotide polymorphisms within INHA and ACVR2B and litter size in Dazu black goats. In total, twenty-two SNPs were genotyped in 190 individuals by SNaPshot and resequencing. The results showed that three SNPs (SNP_1, SNP_12 and SNP_13 in this study) were detected to have significant additive genetic effect on the recorded goat litter size (p < .05). The SNP_1 (NC_030809.1), a non-synonymous substitution of G for T at chr2-g. 28314990 in the exon 2 of INHA gene (NM_001285606.1), resulted in homozygote 2 (HOM2) contributed 0.25 and heterozygote (HET) contributed 0.12 larger litter than homozygote 1 (HOM1). Meanwhile, SNP_12 (Chr22-g. 11721225 A > T) and SNP_13 (Chr22-g. 11721227 A > C) (NC_030829.1) simultaneously mutated at the first and third position of a triplet AAA (lysine, K) in the exon 4 of ACVR2B gene (XM_018066623.1) had estimated genetic effects of HOM1 (0.00) and HOM2 (0.03) larger than HET (−0.12). In conclusion, one SNPs (chr2-g. 28314990 T > G) within the exon 2 of INHA and two SNPs (Chr22-g. 11721225 A > T and Chr22-g. 11721227 A > C) i n the exon 4 of ACVR2B gene were highly recommended as candidate markers of litter size in Dazu black goats. A large-scale association study to assess the impact of these variants on litter size is still necessary.     

山下黑猪与鲁莱黑猪正反交F1代杂种优势的估计

旨在估计山下黑猪和鲁莱黑猪正反交F₁代杂种优势，筛选出合适的杂交方式，以提高优质肉猪的生产效率，满足人们对于优质猪肉的需求。本研究在山下黑猪（164头）和鲁莱黑猪（69头）及其正（6头山下黑猪♂×25头鲁莱黑猪♀）、反（3头鲁莱黑猪♂×35头山下黑猪♀）交4个群体中测定了生长肥育、体尺外貌（75～110 kg）、繁殖和胴体肉质（90～115 kg）4大类共43个性状，比较了这些性状在群体间的差异，并估计了正反交F₁代的杂种优势。结果表明，山下黑猪的生长肥育和体尺性状较好，鲁莱黑猪的繁殖和肉质性状较好，正反交群体介于它们之间。正交群体的繁殖性能优于反交群体，但生长肥育性能比反交差。由于这4个群体的母猪都是纯种，因此繁殖性状没有表现出明显杂种优势。除膘厚、胸椎数、45 min pH和剪切力无显著的杂种优劣势外，大部分胴体性状和肉质性状有明显的杂种劣势。生长肥育性状的杂种优势在正反交群体中的表现不一致，反交群体表现出显著杂种优势，而正交则无明显的杂种优势。本研究估计了山下黑猪和鲁莱黑猪正反交的杂种优势，为筛选山下黑猪和鲁莱黑猪的最佳杂交方式奠定基础。     

Differences in the effectiveness of reproduction among ten breeding strains of the common carp Cyprinus carpio L. after stimulation of ovulation with carp pituitary homogenate or [(D‐Ala6, Pro9NEt) mGnRH‐a + metoclopramide] (Ovopel)

This study focused on the reproduction effectiveness of 10 breeding strains of common carp (Polish strains 2, 3, 6; Hungarian strains 0, W, 7; Lithuanian strain B; French strain F; Israeli strain D and Yugoslavian strain J) after stimulation of ovulation with carp pituitary homogenate or Ovopel. The percentage of females with recorded ovulation became higher after Ovopel treatment in as many as eight breeding strains (2, 3, 6, 0, W, B, F, D). The interaction between the spawning agent and the breeding strain was statistically significant (P ≤ 0.05) for the mass of spawn and non‐significant for traits determining the quality of eggs. Among the 10 breeding strains, in 4 (3, 7, B, J) the least‐squares means (LSM) for the weight of egg (g) were higher for fish stimulated with Ovopel. Among the strains tested, in seven (3, W, F, J, 2, 7, B), the LSM for the percentage of living embryos after 36 h incubation were higher for fish treated with Ovopel. The evaluation of reproduction effects based on the values of such parameters as the percentage of ovulating females, weight of eggs (g) and the percentage of live embryos (36 h) showed that after Ovopel treatment the poorer effects were obtained only for strains 6, 0 and D.     

Isolation of infectious microalga Prototheca wickerhamii from a carp (Cyprinus carpio) – a first confirmed case report of protothecosis in a fish

Protothecosis is a rare infection caused by environmentally ubiquitous achlorophyllic microalgae of the genus Prototheca. Here, we describe a first case of protothecosis in a carp (Cyprinus carpio), which is at the same time the first case of protothecosis in a fish, confirmed by phenotype‐ and molecular‐based methods, including PCR sequencing of the rDNA cluster and protein profiling using matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry.     

射流式鱼泵输送草鱼的性能研究

为了分析射流式鱼泵输送草鱼的性能及其损伤因素,文章设计了一台喉管直径为60 mm的射流式鱼泵,开展了草鱼输送实验,并采用高速摄影和计算流体力学方法进行了研究。结果显示,该射流式鱼泵在扬程2.24m时最高草鱼输送能力达918 kg·h~(-1),其所需水功率为2.83 k W。进一步的检测表明,部分实验鱼有鳞片脱落的情况,但未出现游泳异常,解剖后也未发现内脏受损等情况;实验鱼在过泵后呼吸频率及部分血液指标存在明显变化,但在24 h内基本可以恢复。数值模拟和高速摄影方法分析得出,剪切层是造成实验鱼泵内鳞片脱落的主要原因,撞击伤是由内流偏转诱导实验鱼撞击泵内壁面产生的,包含压力梯度在内的水力因素都可能使实验鱼产生应激反应。但由于鱼类在泵内时间极短,上述因素都不会致实验鱼死亡。     

Cyprinid herpesvirus 3 as a potential biological control agent for carp (Cyprinus carpio) in Australia: susceptibility of non‐target species

Carp (Cyprinus carpio L.) is a pest species in Australian waterways, and cyprinid herpesvirus 3 (CyHV‐3) is being considered as a potential biological control (biocontrol) agent. An important consideration for any such agent is its target specificity. In this study, the susceptibility to CyHV‐3 of a range of non‐target species (NTS) was tested. The NTS were as follows: 13 native Australian, and one introduced, fish species; a lamprey species; a crustacean; two native amphibian species (tadpole and mature stages); two native reptilian species; chickens; and laboratory mice. Animals were exposed to 100–1000 times the approximate minimum amount of CyHV‐3 required to cause disease in carp by intraperitoneal and/or bath challenge, and then examined clinically each day over the course of 28 days post‐challenge. There were no clinical signs, mortalities or histological evidence consistent with a viral infection in a wide taxonomic range of NTS. Furthermore, there was no molecular evidence of infection with CyHV‐3, and, in particular, all RT‐PCRs for viral mRNA were negative. As a consequence, the results encourage further investigation of CyHV‐3 as a potential biocontrol agent that is specific for carp.