Differential levels of antioxidants in paraquat-resistant and -susceptible Erigeron canadensis biotypes in Korea

To characterize the biochemical differences in paraquat-resistant and -susceptible biotypes of Erigeron canadensis L. collected from Korea, we investigated the constitutive levels of various antioxidants such as antioxidant enzymes and low molecular weight antioxidants in leaves, as well as after paraquat treatment. The activities of superoxide dismutase, peroxidase, ascorbate peroxidase, and catalase were higher in the paraquat-resistant biotype than in the paraquat-susceptible biotype. Reduced ascorbic acid content was higher in the resistant biotype, but the content of reduced glutathione was higher in the susceptible biotype. These results indicate that one of the paraquat-resistant mechanisms in E. canadensis in the present study might be related to protecting the activities of antioxidant enzymes, such as superoxide dismutase, peroxidase ascorbate peroxidase, and catalase, as well as the contents of low molecular weight antioxidants such as ascorbate and glutathione.     

Evidence of density-dependent effects on population variation of Japanese sardine (Sardinops melanosticta) off Korea

Interannual variation of some biological parameters for the Japanese sardine, Sardinops melanosticta, population in Korean waters was investigated using scientific surveys and fisheries information since the late 1970s. The abundance and geographical coverage of sardine eggs were high (peak in 1986) and broad when spawning biomasses were high in the mid 1980s, and vice versa in the late 1970s and the early 1990s. Also, feeding and spawning areas based on fisheries information exhibited the same pattern of expansion/contraction as seen in ichthyoplankton surveys. Annual Gonadal Somatic Index (GSI) in spawning season (February to April) and the size at age 1 of sardine were reduced during the high abundance period. It is suggested that density‐dependent effects on the reproduction and growth of the sardine population in Korean waters existed.     

Physiological basis of differential phytotoxic activity between fenoxaprop-P-ethyl and cyhalofop-butyl-treated barnyardgrass

This study investigated the physiological causes of differences in phytotoxic symptoms shown in barnyardgrass from foliar applications of the herbicides fenoxaprop-P-ethyl and cyhalofop-butyl. When these were applied to the third leaves of the whole plant, the chlorosis and desiccation in the third leaf was greater in fenoxaprop-P-ethyl than cyhalofop-butyl. However, initial growth inhibition of the fourth leaf was greater when using cyhalofop-butyl than when using fenoxaprop-P-ethyl. In the shoot regrowth test, regrowth at five days after treatment (DAT) was smaller in cyhalofop-butyl than in fenoxaprop-P-ethyl; the regrowth at 10 DAT exhibited the reverse trend. The chlorosis (decrease of chlorophylls: carotenoids ratio) in barnyardgrass leaf segments that were floated on herbicide solution was greater in the fenoxaprop-P-ethyl treatment. These results indicate that different herbicidal responses induced by the two herbicides are likely to be related to differential translocation and metabolism. The relatively light chlorosis and desiccation in treated leaves, severe cessation of initial growth (but a lower final herbicidal efficacy in the cyhalofop-butyl treatment) are probably related to its rapid translocation to the meristem region from the treated leaf, followed by faster metabolism. In contrast, the relatively greater chlorosis and desiccation compared to inhibition of initial growth in the fenoxaprop-P-ethyl treatment is likely to be related to its relatively slower translocation and metabolism in the treated leaf.     

鲫皮肤蛋白质组双向电泳与部分蛋白点的质谱鉴定

为了建立鱼类皮肤蛋白质组双向电泳图谱及质谱鉴定,以鲫为实验动物,采用蛋白双向电泳(2-DE)结合基质辅助激光解吸电离飞行时间质谱(MALDI-TOF/TOF-MS)技术,进行鲫皮肤的蛋白质组学研究。结果表明,当上样量为800μg,采用18 cm、p H3~10 IPG胶条,等电聚焦80 000 Vh,2-DE图谱检测为214个皮肤蛋白点,匹配率达88%;对其中31个蛋白点进行MS/MS鉴定为22种蛋白,包括肌球蛋白、肌动蛋白、角蛋白、锌指蛋白585B、效应蛋白Rab15、卷曲螺旋结构域蛋白168、NCK1相关蛋白,肌酸激酶、烯醇化酶、丙酮酸脱氢酶、腺苷酸激酶同工酶等;进行蛋白功能聚类(GO)分析发现12种生物学过程,主要参与代谢、细胞、有机体、免疫应答、生物调节和信号等过程。本研究首次初步揭示鲫皮肤蛋白质组及分子机制,以期为鱼类病害的预防和治疗提供科学参考。     

斑马鱼肠道细菌的16S rDNA分子鉴定及PCR-SSCP分析

为了解斑马鱼Danio rerio肠道细菌多样性,采用细菌分离纯化、16S r DNA基因分子鉴定技术,对斑马鱼肠道细菌进行PCR-SSCP分析。结果表明:从斑马鱼肠道分离纯化出12株细菌,分别命名为Zf1、Zf2、Zf3、Zf4、Zf5、Zf6、Zf7、Zf8、Zf9、Zf10、Zf11和Zf12,其中对7株分离菌构建p MD18-T/16S r DNA的阳性克隆测序显示,Zf1、Zf11菌株与Aeromonas veronii的16S rDNA序列一致性为99%,Zf4、Zf8菌株与Sphingomonas sp.的一致性为99%,Zf5菌株与Bacillus subtilis的一致性为99%,Zf7菌株与Aeromonas sp.M10的一致性为99%,Zf10菌株与uncultured bacterium clone GI3-M-5-G01的一致性为92%;16S r DNA分子鉴定表明,Zf1、Zf7和Zf11属于气单胞菌属Aeromonas,Zf4、Zf8属于鞘氨醇单胞菌属Sphingomonas,Zf5属于芽孢杆菌属Bacillus,Zf10为一种新菌株;采用PCR-SSCP技术对12株细菌16S r DNA基因V3区进行多态性分析,结果显示,斑马鱼肠道细菌16S r DNA基因V3区存在多态性,其中Zf1与Zf11菌株带型一致,Zf4与Zf8菌株带型一致。本研究结果可为揭示鱼类肠道菌群结构对其生命活动的影响提供科学参考。     

草鱼肠道约氏不动杆菌的分离鉴定及药敏特性研究

研究草鱼肠道不动杆菌,为鱼类肠道细菌的分离鉴定与微生态机制研究积累资料。从草鱼肠道中分离纯化获得1株细菌,编号为SW-2,采用细菌形态观察、生理生化特性分析、16S rDNA克隆测序及系统发育树构建等进行研究。结果表明SW-2菌株为革兰氏阴性短杆菌,对葡萄糖、甘露糖、木糖、枸椽酸盐利用等均为阴性;PCR方法扩增SW-2菌株16S rDNA并亚克隆至pMD18-T载体,测序获得序列长度为1 503 bp,与约氏不动杆菌(Acinetobacter johnsonii)序列相似性最高为99.7%;进一步构建系统发育树显示与A.johnsonii亲缘关系最近,自然聚类为一支,从而确定为约氏不动杆菌(A.johnsonii);药敏试验结果显示SW-2菌株对庆大霉素、羧苄青霉素、阿莫西林、氨苄西林、卡那霉素等药物敏感。人工回归感染草鱼7 d后未出现发病死亡现象,但是否为条件致病菌有待进一步研究。     

鲶源维氏气单胞菌的分离鉴定及药敏特性

为探明发病怀头鲶Silurus soldatovi的病原及其生物学特征,从发病怀头鲶体内分离出1株革兰氏阴性细菌SG-1,通过细菌形态学观察、理化特性、16S r DNA测序和构建系统发育进化树分析对其进行了鉴定。结果表明:分离菌SG-1菌株葡萄糖产气、氧化酶、硝酸盐还原为阳性,鸟氨酸脱羧酶、硫化氢为阴性;进一步采用PCR方法扩增其16S r DNA序列,测序获得片段大小为1409 bp,与维氏气单胞菌Aeromonas veronii模式菌株ATCC35624序列相似性达99.86%;构建系统发育树分析显示,分离菌与维氏气单胞菌自然聚为一支,最终判定SG-1菌株为维氏气单胞菌;人工感染斑马鱼Danio rerio、鲶S.soldatovi,其死亡率均达100%,病鱼呈现体表出血、肛门红肿、腹水等症状;药敏试验结果显示,该菌对头孢克肟、头孢哌酮、头孢噻肟、诺氟沙星、左氟沙星、恩诺沙星、氟苯尼考等药物敏感,对阿莫西林、氨苄西林、磺胺异恶唑、甲氧嘧啶、复方新诺明等耐药。本研究结果为了解维氏气单胞菌感染鲶的致病机理及其该病的预防治疗提供了科学参考。     

鱼源嗜水气单胞菌全菌蛋白双向电泳与质谱鉴定

为建立鱼源嗜水气单胞菌全菌蛋白图谱并进行质谱分析,利用双向电泳(2-DE)结合基质辅助激光解吸电离飞行时间质谱(MALDI-TOF/TOF-MS)技术对嗜水气单胞菌的蛋白质组学进行鉴定研究。结果显示,嗜水气单胞菌28°C培养12 h、三氯醋酸(TCA)/丙酮沉淀法提取全菌蛋白、等电聚焦20 000 Vh的2-DE图谱匹配率达81%;采用18 cm、p H 3-10 IPG胶条进行2-DE分析获得146个蛋白点,随机选取部分蛋白点进行肽质量指纹图谱(PMF)分析,共鉴定23个蛋白点包括膜脂蛋白、分子伴侣、30S核糖体蛋白S1、延伸因子、细胞色素C等,其中发现烯醇化酶、甘油醛-3-磷酸脱氢酶、二氢硫辛酰胺脱氢酶、精氨酸脱亚氨酶、ATP合酶α亚基、脱氧核糖核酸聚合酶亚基α、氨基甲酸激酶、腺苷酸激酶、尿苷磷酸化酶、硝基还原酶、肽酰脯氨酰异构酶共计11个代谢相关蛋白酶;基于分子功能进行蛋白分类(GO)分析,发现主要为结合(17.1%)、催化(14.3%)和转移酶(11.4%)等生物学过程。建立鱼源嗜水气单胞菌全菌蛋白图谱与部分蛋白鉴定,有助于理解嗜水气单胞菌的蛋白质组学及其分子机制。