A3α-肽聚糖对凡纳滨对虾磷酸酶及细胞内酚氧化酶活性的影响

为考察A3α-肽聚糖(Peptidoglycan,PG)在凡纳滨对虾(Litopenaeus vannamei)的养成期对其免疫酶活性的影响,设立了连续投喂、间隔投喂和浸浴共6个实验组。连续投喂组中PG的添加量分别为0(对照)、0.01%、0.05%和0.1%;间隔投喂组中PG的添加量为0.05%;浸浴组的给予方式为50mg/ml,3h/次/15d。分别在30、60和90d时,测定对虾体内及血浆上清中的酸性磷酸酶(Acid phosphatase,ACP)和碱性磷酸酶(Alkaline phosphatase,AKP)活性,另外,在60d和90d时,测定对虾血细胞内酚氧化酶(Phenoloxidase,PO)活性。结果表明,30d时,PG浸浴组、0.05%和0.1%PG添加量组的ACP活性,各PG作用组的AKP活性均较对照组高,且0.1%PG添加量组的ACP活性及0.05%和0.1%PG添加量组的AKP活性较对照组增长显著(P<0.05);60d时,除间隔投喂组外,各组的ACP活性均较对照组高,且0.1%PG添加量组增长显著(P<0.05),而各实验组的AKP活性均较对照组高,且0.05%PG添加量组增长显著(P<0.05),除浸浴组外,各组血细胞内PO活性均有提高;90d时,浸浴组和间隔组的ACP和AKP活性均较对照组高,且间隔投喂组的AKP活性增长显著(P<0.05);间隔投喂组的血细胞内PO活性较对照组有增长。实验证明,PG能激活对虾的免疫力,并可作为免疫增强剂应用于对虾的生产。     

对虾白黑斑病的病原病因研究

对虾白黑斑病是养殖中国对虾的常见病，曾被怀疑是细菌性疾病，本试验通过对病虾肝胰腺、血液和病灶组织的细菌分离，对正常虾用白黑斑虾的细菌注射感染等一系列试验发现：细菌或其它生物性病原与对虾白黑斑病并无直接关系。     

蝴蝶和蝗虫肠道共生菌次生代谢产物的分离

测定长尾潜蝇茧蜂（Diachasmimorpha longicaudata）寄生的4日龄橘小实蝇（B. dorsalis）幼虫体内过氧化氢酶（CAT）、过氧化物酶（POD）、超氧化物歧化酶（SOD）、酚氧化物酶（PO）活性。结果表明：幼虫在被寄生后,在其免疫系统的调节下产生大量的活性氧自由基（ROS）,致使被寄生的幼虫较未被寄生的3种抗氧化物酶（CAT、POD、SOD）活性明显高,然而被寄生的幼虫PO活性明显低于未被寄生的幼虫。这4种酶协同作用,从而有效减少寄主体内过量的ROS,保证寄生蜂能有效地寄生,提     

Inhibitory effects of Schiff analogs of salicylidene aniline on phenoloxidase from Pieris rapae L. (Lepidoptera: Pieridae)

In order to gain insight into the development of insecticides with novel modes of action, the effects of salicylidene aniline (a), salicylidene-4-chloroaniline (b), salicylidene-4-bromoaniline (c), and salicylidene-4-nitroaniline (d) on partially purified phenoloxidase (PO) from Pieris rapae L. were investigated. The results showed that the 4 compounds could inhibit PO activity, and the inhibitor concentrations leading to a loss of 50% activity (IC₅₀) were estimated to be 0.025 mmol L⁻¹, 0.732 mmol L⁻¹, 0.471 mmol L⁻¹, and 0.675 mmol L⁻¹, respectively. Meanwhile, all the inhibitors showed reversible competitive inhibition, except (d), which showed reversible mixed inhibition. The K_I values were determined as 0.106 mmol L⁻¹, 10.059 mmol L⁻¹, 8.390 mmol L⁻¹, and 20.198 mmol L⁻¹ for the four compounds, respectively. The UV-vis spectra of (a) and (d) in the presence of copper ions and the enzyme showed that (a) could directly chelate the copper ions of PO; however, (d) could neither chelate the additional copper ions nor the copper ions of PO.     

Enzymatic dynamics of catechol oxidase from Gastrolina depressa

Properties of the phenoloxidase (PO) from adult of Gastrolina depressa Baly (Coleoptera: Chrysomelidae) as well as effects of some metal ions and inhibitors on the activity of PO purified by (NH₄)₂SO₄ were determined. The optimal pH and temperature of the enzyme for the oxidation of catechol were determined to be at pH 7.5 and at 40 °C, respectively. The kinetic parameters for the oxidation of L-DOPA and catechol by the PO were 15.01 and 9.17 mM, respectively. The PO activity was strongly inhibited by Zn²⁺ and Cu²⁺, different to Mg²⁺ slightly. Both ascorbic acid and cysteine exhibited competitive inhibition and the inhibitory constants (K_i) were determined to be 2.22 mM and 0.40 mM, respectively.     

曲酸对小菜蛾酚氧化酶抑制作用的研究

 研究了曲酸对小菜蛾酚氧化酶的单酚酶和二酚酶活力的影响并初步探讨了其抑制作用机理，结果表明,曲酸对小菜蛾酚氧化酶的单酚酶和二酚酶活力均有抑制作用，其I50分别为0.07 mmol·L-1和1 mmol·L-1。曲酸对单酚酶活力表达的迟滞时间有明显的延长效应，对二酚酶的抑制作用表现为典型的可逆竞争型抑制类型，其抑制常数Ki为0.47 mmol·L-1。曲酸与酚氧化酶中催化氧化反应活性中心的Cu2+鳌合可能是其产生抑制作用的重要原因。金属铁离子可明显地缩短单酚酶的迟滞时间，但对单酚酶的活力无明显影响。     

不同提取方法对东亚飞蝗酚氧化酶活性的测定与比较

[目的]研究东亚飞蝗酚氧化酶活性及动态变化。[方法]通过不同抽提方法制备虫体体液和淋巴液,测定不同位点酚氧化酶活性及动态变化。[结果]血淋巴中酚氧化酶活性显著高于虫体体液中酚氧化酶活性,且雌虫酶活性显著高于雄虫;虫体体液内酚氧化酶活性随着体外放置时间的延长而显著增强;成虫血淋巴内酚氧化酶活性随着时间的延长而显著增强。[结论]酚氧化酶一部分存在于东亚飞蝗组织和细胞中参与虫体发育和构建,一部分存在于血淋巴中参与免疫防御作用。酚氧化酶稳定性非常强,是昆虫宽泛适应能力和强大免疫能力的有效保障。     

Inhibitory Effects of Kojic Acid on Phenoloxidase of Diamondback Moth Plutella xylostella

The effects of kojic acid on phenoloxidase (PO) of Plutella xylostella were investigated, when it had been partially purified by 40% saturated [(NH4)2SO4] and Sephadex G-100 gel filtration. Kojic acid showed inhibitory effects on both monophenolase and o-diphenolase activity of the PO. The inhibitor concentrations leading to 50% (IC50) activity lost were estimated to be 0.07 mmol L-1 for monophenolase and 1 mmol L-1 for diphenolase, respectively. Kojic acid can also prolong the lag time of PO for oxidation of L-tyrosine. The inhibition kinetics were analyzed by Lineweaver-Burk plots and kojic acid was found to be a reversible competitive inhibitor with the Ki of 0.47 mmol L-1. The ability of kojic acid to inhibit the enzyme activity may be associated with its ability to chelate copper at the active site. In addition, the iron ion was found to shorten the lag time obviously, but have no important effect on the monophenolase activity.     

南美白对虾和罗氏沼虾血细胞中酚氧化酶活力的比较

对比研究了不同化合物对南美白对虾和罗氏沼虾血细胞溶解上清液(HLS)中酚氧化酶原激活系统(pwPO系统)的激活效果.实验结果表明南美白对虾和罗氏沼虾HLS中proPO系统可以被多种化合物激活.其中实验用内源性激活剂以LPS的激活作用最强,Laminarin、Zymosan A、β-1,3-1,6-glucan和Peptide的激活效果次之;外源性激活剂中SDS对2种虾都有显著的激活作用,而Trpsin对南美白对虾的激活作用不显著,对罗氏沼虾激活作用显著;金属离子Ca2+和Mg2+对proPO系统都有激活作用,对南美白对虾HLS中PO活力,Ca2+的激活作用随着Ca2+浓度的增加而增强,Mg2+在100 mmol/L时激活作用最强,而对罗氏沼虾HLS中PO活力,Ca2+和Mg2+均在20 mmol/L时激活作用最强.     

南极磷虾与鹰爪糙对虾酚氧化酶生化性质对比分析

黑变是南极磷虾(Euphausia superba)贮运流通过程中的突出问题,为探究南极磷虾与普通海捕虾在黑变进程方面的异同,选取南极磷虾和海捕鹰爪糙对虾(Trachypenaeus curvirostris)作为研究对象,对2种虾在(2±1)℃贮藏过程中的黑变进程进行了感官评价,提取其酚氧化酶(PO)并进行了纯化,对2种虾PO的生化性质进行了对比分析。结果显示,冷藏条件下,24 h时南极磷虾的黑变已非常严重,黑变部位主要集中在头胸部、腹部甲壳以及尾节部分。72 h时鹰爪糙对虾的头胸部和尾节部分开始有轻微的黑变,之后逐渐扩散到躯干。南极磷虾和鹰爪糙对虾PO粗酶液经硫酸铵沉淀、Sephadex G-100凝胶过滤后,酶的纯化倍数分别达到17.22和19.67。2种虾PO的最适温度分别为30℃和40℃,南极磷虾PO在低温下仍具有较高的活力。二者的最适pH均为6.0~7.0之间。焦亚硫酸钠、亚硫酸氢钠、4-己基间苯二酚、L-半胱氨酸和抗坏血酸均可较好地抑制2种虾PO活力,其中,4-己基间苯二酚抑制效果最好。研究结果为南极磷虾冷链物流过程中的品质控制提供了依据,同时,为虾死后如何有效抑制其黑变提供了参考。