菲莱氏温扬球虫(Wenyonella philiplevinei)受精和卵囊壁形成的超微结构研究

本文利用透射电镜研究了寄生于家鸭小肠上皮细胞的菲莱氏温扬球虫的受精和卵囊壁的形成过程。作者在感染后96 h 的样品中发现一例大、小配子已受精;小配子已进入大配子中,大配子胞质中有一根纵切的鞭毛,小配子的核呈流体状,位于大配子核附近。卵囊壁是由成囊颗粒内含物进入合子表面的膜之间沉积成层而形成。成囊颗粒Ⅰ形成外层卵囊壁,成囊颗粒Ⅱ形成内层卵囊壁。沉积于膜之间的成囊颗粒Ⅰ内含物逐渐浓缩,堆积成颗粒状,使卵囊壁外层外表面形成颗粒状突起。成熟的卵囊壁由三层组成:即薄的外周膜、外层和内层。其内的合子原生质还被两层单位膜包裹。     

破壁蜂花粉对蛋鸡免疫功能及肠道菌群的影响

试验将槐花蜂花粉进行振动磨超微粉碎破壁,分别按1 g/kg、5 g/kg、10 g/kg三个不同剂量混到蛋鸡饲料中,从7日龄开始饲喂至50日龄,每个剂量分两个试验,试验一用新城疫Ⅳ系疫苗免疫雏鸡,利用β-微量法监测血清中的血凝抑制抗体效价的动态变化;试验二用大肠杆菌油乳苗免疫雏鸡,利用间接血凝法监测血清中大肠杆菌抗体效价的动态变化。分别定期称重捕杀取脾、胸腺、法氏囊,计算免疫器官指数,取肠道内容物计数大肠杆菌和乳酸菌,测定肠道内pH值。结果表明,不同剂量的破壁蜂花粉均能不同程度地提高病毒抗原性抗体效价和菌体抗原性抗体效价,对雏鸡免疫器官的发育以及肠道内环境、菌群的平衡也有一定影响。     

The evolution and application of enzymes in the animal feed industry: the role of data interpretation

ABSTRACT

1. Enzymes have been used commercially for nearly 40 years and save significant costs through sparing of expensive nutrients but the mechanism by which this is achieved is still debated.

2. The research focused on non-starch polysaccharidase (NSPase) enzymes is used as an example of where greater progress could have been made if the details of the work had been described more fully and the analysis of the data generated had been broader in scope and more critical.

3. Lack of standardisation of the details presented in the materials and methods has been identified as a significant barrier to meaningful retrospective analysis and thus limits advances in the understanding of the mode of action of these enzymes.

4. The identity of the enzyme employed and its activity is often lacking, and more importantly the purity is rarely disclosed. Contaminant activities which are neither listed nor assayed could play a significant role in the responses observed.

5. The dose optimum of most enzymes is often considerably higher than that employed in most studies. Thus studies claiming synergy between two ‘activities’ should ensure that the response is not related to each enzyme simply augmenting the dose of just one activity in the finished feed. This is a common problem, and coupled with the lack of factorial experiments to justify the presence of each enzyme in a multi-enzyme product, it is not surprising that there is still debate as to whether single or multi-enzymes are best suited poultry rations.

6. The three proposed mechanisms for NSPases (viscosity, cell wall and prebiotic) are discussed, and along with their strengths and weaknesses it is suggested that a re-evaluation of each is needed. Viscosity may have to be re-evaluated as being a function not only of the cereal being fed, but of the age of the animal as well. The cell wall theory as described is poorly modelled in vitro and hence the validity of these data is questioned. The prebiotic theory may need significant modification as it appears that the quantities of oligomers produced are insufficient to generate the additional volatile fatty acids (VFA)’s reported. It is likely that all three mechanisms play a role in the responses observed, but the prebiotic mechanism probably plays by far the most important part in low viscosity diets.

7. Future research would be improved if it considered all potential mechanisms when designing a trial. Significant failings are apparent as a result of adherence to tenets in explanation of the results. Most importantly, it should be emphasised that a hypothesis is there to be tested, not defended.     

温湿度调控对番茄灰霉病菌产生的细胞壁降解酶的影响

 番茄灰霉病菌在致病过程中能够产生4种细胞壁降解酶,以PMG酶活性最高,其次是β-葡萄糖苷酶和PG酶,Cx最少。灰霉病菌在不同温度下侵染番茄叶片时产生的致病酶活性不同,4种酶在20℃时表现了最高的活性,15℃次之,当温度达到25℃时,各种酶的活性都急剧下降,随着温度的再升高,酶活更低。随着湿度的增高,病菌产生的细胞壁降解酶的活性也增加,当相对湿度达到90%以上时,4种酶的活性也达到最高。温湿度对番茄灰霉病菌产生细胞壁降解酶的影响趋势,与其对发病的影响趋势是一致的。     

Use of real-time PCR to examine the relationship between disease severity in pea and <Emphasis Type="Italic">Aphanomyces euteiches</Emphasis> DNA content in roots

Aphanomyces euteiches causes severe root rot of peas. Resistance is limited in commercial pea cultivars. Real-time fluorescent PCR assay specific for A. euteiches was used to study the relationship between disease severity and pathogen DNA content in infected peas. Five pea genotypes ranging in levels of resistance were inoculated with five isolates of A. euteiches. Plants were visually rated for disease development and the amount of pathogen DNA in roots was determined using the PCR assay. The susceptible genotypes Genie, DSP and Bolero tended to have significantly more disease and more pathogen DNA than the resistant genotypes 90-2079 and PI 180693. PI 180693 consistently had less disease, while 90-2079 had the lowest amount of pathogen DNA. The Spearman correlation between pathogen DNA quantity and disease development was positive and significant (P < 0.05) for three isolates, but was not significant for two other isolates. This suggests that the real-time PCR assay may have limited application as a selection tool for resistance in pea to A. euteiches. Its utility as a selection tool would be dependent on the correlation between disease development and pathogen DNA content for a given pathogen isolate. The accuracy and specificity of the real-time PCR assay suggests considerable application for the assay in the study of mechanisms of disease resistance and the study of microbial population dynamics in plants.     

利用果胶酶改善烟梗内在品质的研究（英文）

[目的]为了降低烟梗中细胞壁物质的含量,改善烟梗的内在品质。[方法]利用果胶酶处理烟梗,降解其细胞壁物质,并对烟梗中4种细胞壁物质、6种常规化学成分和致香成分进行测定。[结果]果胶酶可有效降低烟梗中细胞壁物质的含量,最高下降幅度为6.84%;果胶酶处理后,烟梗中还原糖含量明显升高,总糖、钾离子、氯离子和总氮也都有不同程度地升高,且随着果胶酶浓度的升高,钾离子、还原糖含量呈上升趋势;果胶酶处理可明显提高美拉德反应产物的量,最高可增加67.2%,类胡萝卜素降解产物、苯丙氨酸降解产物和新植二烯也都有不同程度地提高,且随着酶浓度的升高,美拉德反应产物和苯丙氨酸降解产物的量都有升高趋势。[结论]果胶酶处理烟梗可有效降解其细胞壁物质,改善常规化学成分,并能提高烟梗中致香成分的含量。     

响应面法对鱼肝油微胶囊化复合壁材的优化研究

[目的]优化鱼肝油进行微胶囊化的壁材用量。[方法]以天然鱼肝油为芯材,通过单因素试验研究乳清蛋白、β-环糊精、阿拉伯胶壁材对鱼肝油微胶囊化包埋率的影响,再结合中心组合响应面设计优化复合壁材用量,建立3种壁材用量与包埋率的数学模型。[结果]试验表明,在乳液浓度为25%时,鱼肝油微胶囊化3种壁材乳清蛋白、β-环糊精、阿拉伯胶的最佳使用比例为0.217、0.217、0.217,3种壁材比例为1∶1∶1。在此条件下,鱼肝油微粉的包埋率可达85.44%。[结论]研究可为鱼肝油的高效利用和产品开发提供技术支持。     

酵母SOD1基因缺失突变体应答真菌细胞壁抑制剂CFW的转录组学分析

以酿酒酵母为研究材料,采用酵母全基因组表达谱芯片,分析超氧化物歧化酶SOD1基因缺失(sod1Δ)对酵母细胞应答真菌细胞壁抑制剂钙荧光白(CFW)全基因组转录表达谱的影响,为揭示植物病原真菌细胞壁调控机制以及植物抗真菌基因工程改造提供新的理论基础。结果表明:CFW(10μg/m L)处理1 h后,与野生型酵母细胞相比,sod1Δ酵母细胞中211个基因发生了显著差异表达(97个基因表达上调、114个基因表达下调)。随机选取5个差异表达基因采用定量PCR验证,结果与芯片分析结果一致。差异表达基因功能主要涉及细胞壁、细胞代谢、蛋白质合成、细胞防御以及大量功能未知蛋白。以上结果表明,SOD1基因缺失可显著改变酵母细胞应答真菌细胞壁抑制剂CFW胁迫的全基因组转录表达谱。     

Role of Salicylic Acid in Alleviating Cadmium Toxicity in Rice Roots

In order to understand how salicylic acid (SA) is involved in modulating rice responses to cadmium (Cd) toxicity, particularly in Cd immobilization, a series of hydroponic experiments were conducted to examine changes in cell wall composition, activities of the enzymes related to lignin synthesis including phenylalanine ammonia-lyase (PAL), peroxidase (POD), and polyphenol oxidase (PPO), subcellular Cd distribution, levels of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and lignin and non-protein thiols (NPT) in rice roots under Cd stress with or without the pretreatment of SA. Results showed that Cd treatment decreased root biomass by 40% compared with the control (no Cd treatment) and pretreatment with SA significantly mitigated the Cd-induced inhibition of root growth. There was no significant difference in root cell wall composition or lignification between the treatment with Cd alone and the treatment with Cd with SA. No effects were observed for SA pretreatment on the activities of PAL, POD, or PPO under Cd stress. Furthermore, soluble Cd concentrations in root cells were significantly higher in the treatment with Cd with SA than in the treatment with Cd alone. However, H₂O₂ and MDA concentrations in rice roots were significantly lower but NPT levels were higher in the treatment with Cd with SA than in the treatment with Cd alone, which indicated that SA alleviated Cd-induced oxidative damage. It seems to suggest that SA-mediated enhancement of Cd tolerance was not due to enhanced Cd retention in the cell wall but to enhanced Cd bindings with thiols (─SH) group. The effects of SA-enhanced Cd tolerance were discussed with regard to H₂O₂ signaling pathways.     

粘性Cahn-Hilliard方程的高精度线性化差分方法

讨论粘性Cahn-Hilliard方程的高精度线性化差分方法.利用降阶法对粘性Cahn-Hilliard方程建立三层线性化紧差分格式.用离散能量分析法证明差分格式的唯一可解性及在L_∞-范数下的收敛性,其收敛阶为时间方向二阶、空间方向四阶.最后,通过数值算例验证了差分格式的理论结果.