Application of acoustic Doppler current profiler combined with a scientific echo sounder for krill Euphausia pacifica density estimation

ABSTRACT:   An application of the acoustic Doppler current profiler (ADCP, 153.6 kHz) in combination with a scientific echo sounder (EK60, 38 and 200 kHz) was investigated to estimate the density of krill Euphausia pacifica . The acoustic backscattering strength from sound scattering layers was compared with biomass estimates from midwater trawls. Euphausia pacifica was targeted among mixed species populations in the sound scattering layer in the offshore Funka Bay area of Hokkaido, Japan. The frequency characteristics of acoustic backscattering by krill were calculated using a distorted wave Born approximation scattering model at three frequencies. Krill aggregations identified from the EK60 data were extracted as the mean volume backscattering strength difference between two frequencies. They were then used to identify similar aggregations in the ADCP data by matching observation times and depths for the two methods, which were applied simultaneously. Results from the comparison of the mean volume backscattering strength and the density calculated from the ADCP and EK60 showed that ADCP can be used to measure density and spatial–temporal distribution of krill aggregations. Current speed and direction at the study site were found to be 16.1 cm/s and 187.0°, respectively, and krill speed and direction (including the current component) were found to be 19.8 cm/s and 172.2°, respectively. Based on the ADCP data, the net speed and direction of the krill aggregations were found to be 5.9 cm/s and 128.0°, respectively.     

酥梨采后灰霉病生防菌株的鉴定及抑菌作用

以微生物拮抗病原菌是防治病害安全高效的可行手段。通过对果实表面微生物进行筛选鉴定,以期得到一株可以有效抑制灰霉病的生物防治菌株。对拮抗菌株H-1进行形态学特征、生理生化特性分析,结合16S rDNA序列分析和gyrB 基因序列分析构建系统发育树;采用平板对峙法结合果实伤口试验考察拮抗菌H-1在体外及梨果表面的抑菌作用。结果表明：经鉴定H-I菌株为贝莱斯芽孢杆菌（Bacillus velezensis）;B. velezensis H-1在体外条件下可显著抑制灰葡萄孢霉（Botrytis cinerea）、细极链格孢（Alternaria tenuissima）和串珠镰孢菌（Fusarium verticillioides）的菌丝生长,其中对灰葡萄孢霉菌丝的抑制作用最强;果实伤口试验表明,1×1011 CFU/mL的B. velezensis H-1可完全抑制梨果表面灰霉菌生长。由此可见,B. velezensis H-1可以有效抑制梨果采后灰霉病的发生。     

Detection of squash mosaic virus in seeds of melon (Cucumis melo) by enzyme-linked immunosorbent assay (ELISA)

Squash mosaic virus (SqMV, comovirus) is seed-transmitted in severalCucurbitaceae. Therefore, the use of virus-free seed is important to prevent establishment of this virus in the Netherlands and to avoid spread to other countries.This study was undertaken to develop an enzyme-linked immunosorbent assay (ELISA) for the detection of SqMV in melon seeds. An antiserum was produced to a serotype 1 isolate from melon. Two ELISA variants were investigated viz. an ELISA variant with simultaneous incubation of sample and enzyme conjugate (ELISA 1) and an ELISA variant with successive incubation of sample and enzyme conjugate (ELISA 2). The sensitivity of ELISA was tested by mixing fluor of ground infected and non-infected seeds in different proportions. SqMV was detected by both ELISA variants at dilutions of 1 160 (1 part of infected flour mixed with 159 parts of non-infected flour) or higher after a substrate incubation period of 4 h. However, ELISA 1 gave relatively higher absorbance values than ELISA 2 for nearly all dilutions. Since ELISA 1 is also faster than ELISA 2, ELISA 1 is advised for routine testing. In these test, using subsamples of 100 melon seeds SqMV is detected reliably. ELISA 1 is now used in the Netherlands for routine-indexing of melon seed lots for SqMV.Samenvatting Het pompoenemozaïekvirus gaat over met het zaad van verscheideneCucurbitaceae. Het gebruik van virusvrij zaad is belangrijk om te voorkomen dat het virus zijn intrede doet in Nederland en zich naar andere landen verspreidt.Een antiserum werd geproduceerd tegen een serotype 1 isolaat van meloen. Met behulp van dit antiserum werd een ELISA ontwikkeld om pompoenemozaïekvirus in zaden van meloen aan te tonen. Twee varianten van ELISA werden vergeleken, namelijk een variant waarbij monster en enzymconjugaat gelijktijdig geïncubeerd werden (ELISA 1) en een variant waarbij monster en enzymconjugaat na elkaar geïncubeerd werden (ELISA 2). De gevoeligheid van de ELISA varianten werd uitgetoetst door meel van zieke zaden in verschillende verhoudingen te mengen met meel van gezonde zaden. Het pompoenemozaïekvirus werd met beide ELISA varianten aangetoond in verdunningen van 1 160 (1 deel meel van zieke zaden gemengd met 159 delen meel van gezonde zaden) of hoger na 4 uur incubatie met substraat. ELISA 1 gaf doorgaans hogere extinctiewaarden dan ELISA 2 voor bijna alle verdunningen. Omdat ELISA 1 ook nog sneller is dan ELISA 2, wordt ELISA 1 aanbevolen voor routinematig gebruik. Wanneer voor routinematig gebruik 100 meloenezaden per submonster getoetst worden, kan het pompoenemozaïek virus betrouwbaar worden aangetoond. In Nederland worden momenteel per zaadpartij 20 submonsters van 100 zaden getoetst.     

国内一种玉米新病害--玉米黑腐病

1999年7月云南省元谋县城郊玉米地发现一种玉米新病害,发病面积大约70hm2.其典型症状表现为植株矮化,节间缩短,叶片密集簇生,叶片上有黄绿相间的条斑.叶鞘上有坏死或腐烂病斑,幼穗腐烂,不实,严重者绝产,颗粒无收.从坏死或腐烂的叶鞘和果穗上可镜检到分生孢子及分生孢子梗.纯化培养后,并按柯赫氏法则进行接种试验,病原鉴定为柔弱无枝孢Acladium tenellum(Berk.& Curt.)Subram.comb.nov..本文对病害症状、病原形态、发病情况等进行了详细研究,确定该病为玉米一种新病害.     

乌鲁木齐周边地区奶牛乳房炎沙门氏菌的分离鉴定及耐药性分析

为了解乌鲁木齐周边地区奶牛场奶牛乳房炎沙门氏菌的流行与耐药情况,本研究采集了5个牧场300份奶牛乳房炎奶样,进行沙门氏菌的分离、培养,利用荧光PCR方法鉴定,同时对分离出的阳性菌株采用纸片扩散法进行耐药性分析。结果表明：从奶牛乳房炎样品中分离出12株沙门氏菌,分离率4%;耐药性分析表明分离的沙门氏菌对氨苄西林、四环素、多西环素、链霉素耐药率超过50%,对氨曲南、诺氟沙星、多粘菌素B、头孢他啶敏感性大于70%。此外4株沙门氏菌分离株具有多重耐药性。本研究为本地区奶牛乳房炎的防治提供了依据。     

美洲鲥鱼嗜水气单胞菌病原的分离与鉴定

2021年,山东省临沂市一养殖场养殖的美洲鲥鱼(Alosa sapidissima)突发疾病并出现严重死亡,日死亡率高峰期达到2.5%,累积死亡率约为90%。患病鱼主要症状为体表出血、溃疡,解剖可见腹腔腹水、肝脏暗红,并伴有肠炎。组织病理学检测发现,病鱼肝脏出现弥散性坏死,嗜碱性粒细胞增多和细胞肿胀空泡变性;脾脏出现出血性贫血性坏死灶、核破裂和核固缩;肾脏淋巴细胞坏死脱落,肾小体毛细血管球萎缩,近端小管和远端小管内的细胞出现不同程度的细胞结构消失。发病鱼肉眼和显微镜观察未见明显寄生虫,利用PCR方法检测鲤疱疹病毒2型(Cyprinid herpesvirus 2)、鲈鱼蛙病毒(largemouth bass ranavirus)等淡水鱼类常见病毒均为阴性。细菌分离培养结果显示,从发病鱼的肝脏、肾脏和脾脏中分离得到形态一致的优势菌,命名为AS-AH2101。经16S rRNA测序比对和生理生化鉴定,确定AS-AH2101为嗜水气单胞菌(Aeromonas hydrophila)。毒力基因检测结果显示,AS-AH2101携带气溶素(aerA)、溶血素(hlyA)、丝氨酸蛋白酶(ahpA)、...     

柔性坐标测量机参数辨识方法

设计了一种六自由度关节式柔性坐标测量机,并对该测量机测量方程中的参数进行了辨识,提出了一种快速简易的单点锥窝标定方法。该方法基于单点锥窝提供的空间单点基准,利用非线性最小二乘中的高斯-牛顿法,求解测量机测量方程的参数值。实验结果表明,该方法能够有效提高测量机的整体精度,且操作简单、计算效率高。     

一例荚膜血清A型多杀性巴氏杆菌和牛肺炎支原体混合感染犊牛的诊治

新疆某牛场的犊牛出现咳喘、鼻镜干燥、精神不振、食欲废绝、呼吸困难甚至出现死亡的症状,通过对患病牛群的发病情况、剖检、细菌分离鉴定、PCR鉴定等试验方法进行检查。结果显示:病死牛肺部可见明显出血并且伴有肺部实质性肝变;牛支原体和多杀性巴氏杆菌PCR检测都为阳性,曼氏杆菌PCR检测为阴性。通过实验室诊断最终确定该牛场为多杀性巴士杆菌和牛肺炎支原体混合感染。本研究通过病理变化、实验室诊断等方法找到病因,为此类疾病的防控提供借鉴意义。     

1株黄曲霉颉颃菌的鉴定及其抑菌活性成分分析

【目的】筛选黄曲霉颉颃菌,探究其最佳培养条件及有效抗菌成分,为实际生产中应用生物防治方法抑制黄曲霉污染提供新的理论依据。【方法】通过平板对峙法及分子生物学鉴定方法对待测菌株进行筛选鉴定。以抑菌率作为衡量标准,判断所得黄曲霉颉颃菌的最佳培养温度、培养时间、接种量、转速、pH及装液量。通过硫酸铵沉淀法从颉颃菌无菌发酵上清液中提取蛋白,观测粗提物对黄曲霉菌丝生长的影响。通过离子交换色谱和凝胶过滤色谱进一步纯化粗提蛋白,并进行质谱测序及序列对比分析,筛选鉴定颉颃菌产生的有效抑菌成分。【结果】筛选到1株解淀粉芽孢杆菌B10(菌种保藏号CCTCCNO:M2018353)。最佳培养条件为温度40℃,培养时间36 h,接种量3%,转速120 r/min, pH 6.0,装液量30 mL,最大抑菌率可达46.56%。其粗提蛋白能有效抑制黄曲霉生长,破坏菌丝正常形态,并从中筛选出几丁质结合蛋白、壳聚糖酶、葡聚糖酶等8种可能的有效抑菌成分。【结论】本试验分离鉴定出1株抑制黄曲霉正常生长发育的解淀粉芽孢杆菌B10,其产生的多种蛋白成分对黄曲霉有显著抑菌活性。     

无花果树苗中截获的无花果孢囊线虫形态和分子鉴定

上海口岸从旅客携带进境的树苗中分离到1种孢囊线虫属的2龄幼虫,通过形态特征和分子特征分析,鉴定为无花果孢囊线虫(Heterodera fici Kirjanova,1954)。该2龄幼虫的主要形态特征为:体长409.9~454.4μm;唇环3个;口针发达,长22.6~24.0μm,基部球圆形略向前倾斜;侧线4条;尾长圆锥形,末端细圆,尾部透明区长24.7~30.5μm,约占尾长的1/2。序列分析显示其ITS区序列与GenBank中无花果孢囊线虫的序列相似性为99.48%~99.90%,序列差异为1~5 bp。系统发育分析显示该线虫与无花果孢囊线虫处于一个聚类组内。这是我国口岸首次报道截获无花果孢囊线虫。