Effects of Yeast Oligosaccharide Diet Supplements on Growth and Disease Resistance in Juvenile Nile Tilapia,Oreochromis niloticus

Commercially available yeast and yeast subcomponents consisting mainly of β-glucan or oligosaccharide feed additives were added to diets of juvenile (12–18g) Nile tilapia (Oreochromis niloticus) at rates recommended by suppliers. Three experiments were conducted following a basic protocol with varied rates of supplementation, duration of feeding, and stocking densities. Experimental diets were fed twice daily to apparent satiation for a period of two or four weeks, at the end of which feed consumption and weight gain were measured. Following the experimental feeding period, serum components, including protein and immunoglobulin concentrations, as well as lysozyme and complement activities, were measured. A disease challenge was conducted with pathogenic isolates of Streptococcus iniae or Edwardsiella tarda. Weight gains were not significantly different in fish fed the supplemented diets when compared to the control diet. There were significant differences in fed intake within individual experiments; however, this effect was not consistent in all three experiments. Overall feed efficiency was not significantly affected by diet. There were no differences in serum components of fish sampled at two or four weeks. Fish fed the experimental diets did not have lower mortality or morbidity after disease challenge compared to fish fed the control diets. Specific antibody against S. iniae or E. tarda measured by ELISA did not reveal differences in the fish surviving the challenge. We conclude that the incorporation of these commercial yeast component products into the diet of juvenile Nile tilapia at these rates and for these feeding periods had no effect on growth, serum components, antibody responses, or survival following S. iniae or E. tarda infection.     

通过染色体整合β-1,4-葡聚糖酶基因glu14提高绿色木霉对小麦纹枯病的防治效果

 绿色木霉LTR-2是生物防治菌株。利用来自巨大芽胞杆菌Ap25的β-1,4-葡聚糖酶基因glu14构建木霉表达载体pSilent/glu14,利用限制性内切酶介导法(REMI)转化绿色木霉LTR-2。PCR扩增及Southern杂交证实目的基因已插入木霉转化子的染色体DNA上。转化子的β-1,4-葡聚糖酶水解活性,对小麦纹枯病菌的平板抑制作用及温室防治效果较原始菌株LTR-2明显提高(P<0.01),其中转化子L-10的效果最好,平板抑制率比LTR-2提高了27.0%,温室防治效果比LTR-2提高了26.7%。本试验表明,利用REMI技术,将β-1,4-葡聚糖酶基因重组到木霉染色体DNA上,是获得高效木霉工程菌株的有效手段。     

水稻与稻瘟病菌非亲和性互作中重要防御酶活性变化规律研究

 选以CO39为背景的水稻抗稻瘟病近等基因系,与稻瘟菌生理小种ZC₁₃(菌株97-151a)组成的3类典型非亲和性互作,以亲和性互作为对照,对各互作中过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、几丁质酶及β-1,3-葡聚糖酶的活性变化规律进行了系统研究。完全非亲和性互作C101A51/97-151a、高度非亲和性互作C101L AC/97-151a及中度非亲和性互作C104 PKT/97-151a,POD比活性接种后即开始明显升高,48h前达到高峰,升高趋势一直持续到7d完全显症时,幅度基本与各互作非亲和程度呈正相关;亲和性互作CO39/97-151a接种后40 h POD比活性才开始升高,4~6 d达到高峰,峰值也较大。3类非亲和性互作PAL比活性在接种后0 h或16 h开始较明显升高,整个互作中形成3~4个较明显的峰;亲和性互作中PAL比活性一直明显下降。3类非亲和性互作外切几丁质酶比活性接种后即开始升高,基本一直保持升高趋势,在40 h前幅度较大,并形成1~3个较高的峰;亲和性互作外切几丁质酶比活性接种后即开始大幅度升高直至完全显症,48h后幅度远高于非亲和性互作。3类非亲和性互作β-1,3-葡聚糖酶比活性在24 h内开始较明显升高,在48h前形成2~3个较明显的峰;亲和性互作在接种后β-1,3-葡聚糖酶比活性即开始升高,在48h后显著高于非亲和性互作。讨论了POD、PAL、几丁质酶及β-1,3-葡聚糖酶参与水稻抗稻瘟病的可能性。     

洱源丛枝瑚杀虫活性成分研究

洱源丛枝瑚(Ramaria eryuanensis)石油醚萃取物经过柱层析得到单体化合物B8,该化合物对小菜蛾3龄幼虫72 h的LC50为3.375 7 mg/mL。经FAB-MS、1HNMR、13CNMR及DEPT等波谱鉴定,并与文献值对照,确定其为麦角甾-7,22-二烯-3β,5α,6β-三醇。     

利用凝胶扩散法测定刺萼龙葵种子中β-甘露聚糖酶的活性

β-甘露聚糖酶是种子萌发过程中降解胚乳细胞壁的关键酶,明确其活性的动态变化可为揭示杂草种子的休眠萌发机制提供重要依据。以外来杂草刺萼龙葵Solanum rostratum Dunal种子为材料,建立了种子中β-甘露聚糖酶活性的检测方法—凝胶扩散法。利用凝胶扩散法对不同贮存时间及贮存条件下刺萼龙葵种子中β-甘露聚糖酶的活性进行了检测,发现贮存3年以上的种子中该酶的活性为0.03 nmol/(min·mg),显著低于贮存3年以下的种子中的酶活性0.15 nmol/(min·mg),而湿润冷藏的种子中β-甘露聚糖酶的活性为0.12 nmol/(min·mg),显著高于干燥冷藏的种子的酶活性0.02 nmol/(min·mg)。实际应用结果表明,凝胶扩散法综合了传统方法的优势,检测特异性强、灵敏度高、重复性好,可同时检测大量种子样品,具有良好的实用性。     

Induction of defense response of Oryza sativa L. against Pyricularia grisea (Cooke) Sacc. by treating seeds with chitosan and hydrolyzed chitosan

Seeds of rice (Oryza sativa L.) were treated with chitosan and hydrolyzed chitosan at 100, 500 and 1000 mg L⁻¹. After 18 days of germination, spore suspension of Pyricularia grisea was applied. The enzyme activity of phenylalanine ammonia-lyase, β-1-3-glucanase, chitinase and chitosanase in leaves of rice seedlings was evaluated after 24, 72, 120 and 168 h of inoculation. Blast affected area (%) was evaluated 7 and 14 days after spraying spore suspension. Chitosan performance to elicit defense response induction was associated with the concentration and type of chitosan. The activity of most of the enzymes tested was induced in leaves of treated seeds with chitosan and hydrolyzed chitosan at 1000 and 500 mg L⁻¹, respectively. The highest enzyme activities were observed with hydrolyzed chitosan after 72 h however, compared to chitosan, the activity was not maintained during the entire post-inoculation period. The highest control (0 = no lesions) of P. grisea in rice seedlings was observed at 1000 mg L⁻¹ in both chitosan and hydrolyzed chitosan treated leaves. Symptoms of infection by P. grisea were evident after 14 days evaluation date, but according to the standard scale proposed by the International Rice Research Institute, these symptoms fell into the resistance category of blast diseases.     

螺旋毛壳ND35 β-1,3-葡聚糖酶的诱导、性质及其抑菌作用

 以病原菌Rhizoctonia solani的细胞壁为诱导物,模拟毛壳菌自然的重寄生过程,研究了内生真菌螺旋毛壳(Chaetomium spirale) ND35 β-1,3-葡聚糖酶的产酶条件、性质,尤其是不同碳源的调控作用。结果表明,不同种类的真菌细胞壁及几丁质和昆布多糖,均可诱导产生β-1,3-葡聚糖酶,而作为分解代谢产物的葡萄糖则抑制产酶。经硫酸铵沉淀、DEAE-Sepharose阴离子交换层析及Phenyl-Sepharose疏水层析,并通过SDS-PAGE鉴定,纯化了一种分子量约为73 kDa的内切β-1,3-葡聚糖酶GLUC73。其最适反应温度为55℃,在40℃以下较稳定;最适pH值为5.5,在pH 5-9范围内均很稳定;酶活性受Hg²⁺、Fe³⁺、Zn²⁺、Mg²⁺等金属离子不同程度的抑制,Mn²⁺和Co²⁺对酶有激活作用;以昆布多糖为底物时,该酶的米氏常数K_m为0.412 mg·mL^-1,最大反直速度V_max为3.876 U·mL^-1。粗酶液同时具有β-1,3-葡聚糖酶和几丁质酶活性,离体抑菌试验表明,对苹果炭疽病菌(Glomerella cingulata)、杨树腐烂病菌(Valsa sordida)、苹果树腐烂病菌(Valsa mali)的菌丝生长和孢子萌发有明显的抑制作用。通过对β-1,3-葡聚糖进行免疫细胞化学标记和超微结构观察,间接证明了β-1,3-葡聚糖酶在螺旋毛壳重寄生过程中的作用。     

Glycinin和β-Conglycinin对不同生长阶段猪生长性能和粗蛋白消化率的影响

选取仔猪(7.06±0.18)kg、生长猪(44.54±9.04)kg和肥育猪(78.93±7.37)kg军牧一号去势公猪各15头,用于3个生长阶段的动物试验,每一阶段分为A、B、C 3组,其中A组为对照组,B、C以Glycinin或β-Conglycinin的提纯产物作为日粮唯一大豆蛋白来源,每组5个重复。仔猪在28日龄断奶,试验分组之前,猪均不接触任何豆科日粮。7 d试验期过后,收集消化道各段食糜,测定干物质和粗蛋白表观消化率。结果表明:Glycinin或β-Conglycinin降低仔猪或生长猪的生产性能以及干物质、粗蛋白在消化道各段的表观消化率(P<0.001),最终导致回肠养分表观消化率的绝对值与对照组相比减少3%～6%。2个生长阶段猪的粗蛋白质表观消化率只在胃中受抗原蛋白的影响有显著差异(Glycinin,P=0.005;β-Conglycinin,P=0.001),仔猪的下降程度大于生长猪。     

雌激素胁迫对萝卜种子萌芽和幼苗生长及其累积效应的影响

通过水培试验,研究了不同浓度17β-雌二醇(17β-E2)胁迫对萝卜种子萌芽、幼苗生长和抗氧化酶系统活性的影响,以及17β-E2在幼苗体内的积累。结果发现,萝卜种子的发芽势、发芽率和根长与17β-E2处理浓度呈负相关,在10 μg/L浓度时17β-E2刺激萝卜种子的发芽势和根长明显增加,诱导幼苗体内抗氧化酶SOD、POD和CAT活性显著上升;但在50 μg/L浓度的17β-E2胁迫下,SOD、CAT和POD活性受到明显抑制,MDA含量显著升高,幼苗抗氧化能力显著降低,膜质过氧化程度加剧;受17β-E2污染,萝卜幼苗体内17β-E2积累量随着处理浓度的升高而增加,其在根部累积量要大于地上部分,在转运过程中发生17β-E2代谢,产生具有低雌激素活性的雌酮。萝卜对17β-E2胁迫具有一定的抗性,在17β-E2污染土壤中种植萝卜存在潜在的食用安全风险。