Trichoderma Biocontrol of Colletotrichum acutatum and Botrytis cinerea and Survival in Strawberry

Trichoderma isolates are known for their ability to control plant pathogens. It has been shown that various isolates of Trichoderma, including T. harzianum isolate T-39 from the commercial biological control product TRICHODEX, were effective in controlling anthracnose (Colletotrichum acutatum) and grey mould (Botrytis cinerea) in strawberry, under controlled and greenhouse conditions. Three selected Trichoderma strains, namely T-39, T-161 and T-166, were evaluated in large-scale experiments using different timing application and dosage rates for reduction of strawberry anthracnose and grey mould. All possible combinations of single, double or triple mixtures of Trichoderma strains, applied at 0.4% and 0.8% concentrations, and at 7 or 10 day intervals, resulted in reduction of anthracnose severity; the higher concentration (0.8%) was superior in control whether used with single isolates or as a result of combined application of two isolates, each at 0.4%. Only a few treatments resulted in significant control of grey mould. Isolates T-39 applied at 0.4% at 2 day intervals, T-166 at 0.4%, or T-161 combined with T-39 at 0.4% were as effective as the chemical fungicide fenhexamide. The survival dynamics of populations of the Trichoderma isolates (T-39, T-105, T-161 and T-166) applied separately was determined by dilution plating and isolates in the mixtures calculated according to the polymerase chain reaction (PCR) using repeat motif primers. The biocontrol isolates were identified to the respective species T. harzianum (T-39), T. hamatum (T-105), T. atroviride (T-161) and T. longibrachiatum (T-166), according to internal transcribed spacer sequence analysis.     

DNA甲基化与基因组印记

综合论述了DNA甲基化与基因组印记的最新研究进展,论述了它们的生物学意义,并阐述了两者的关系.     

H5亚型禽流感DNA疫苗质粒pCAGGoptiHA5对高致病力禽流感病毒攻击的免疫保护

对H5亚型禽流感DNA疫苗质粒pCAGGoptiHA5的免疫效果进行了研究。pCAGGoptiHA5分别以100和10μg剂量一次或两次免疫3周龄SPF鸡，首次免疫后4周以同样剂量和途径进行第二次免疫，一次免疫后4周、两次免疫后2周分别用100LD50的HPAIV A／Goose／GuangDong／1／96（H5N1）鼻腔途径进行攻击，观察发病与死亡情况，分别于攻毒后第3、5、7天采集喉头及泄殖腔拭子进行病毒分离、滴定检测排毒情况，同时检测免疫后、攻毒前及攻毒后血清HI抗体、NT抗体以及AGP抗体的动态变化。结果，100μg pCAGGoptiHA5一次免疫、100μg pCAGGoptiHA5两次免疫以及10μg pCAGGoptiHA5两次免疫均可对免疫鸡形成100％完全保护（不发病、不致死、不排毒），10μg剂量pCAGGoptiHA5一次免疫可对免疫鸡形成100％的保护（不发病、不致死），结果表明，pCAGGoptiHA5作为疫苗效果良好、成本低廉，有望成为预防H5亚型高致病力禽流感的高效、安全新型基因工程疫苗。     

Methyl donors dietary supplementation to gestating sows diet improves the growth rate of offspring and is associating with changes in expression and DNA methylation of insulin‐like growth factor‐1 gene

The study aimed to investigate the effects of maternal dietary methyl donors on the performance of sows and their offspring, and the associated hepatic insulin‐like growth factor‐1 (IGF‐1) expression of the offspring. A total of 24 multiparous sows were randomly fed the control (CON) or the CON diet supplemented with methyl donors (MD) at 3 g/kg betaine, 15 mg/kg folic acid, 400 mg/kg choline and 150 μg/kg VB₁₂, from mating until delivery. After farrowing, sows were fed a common lactation diet through a 28‐days lactation period and six litters per treatment were selected to be fed until at approximately 110 kg BW. Maternal MD supplementation resulted in greater birthweight (p < 0.05) and increased the piglet weights (p < 0.01) and litter weights (p < 0.05) at the age of day 28, compared with that in CON group. The offspring pigs in the MD group had greater ADG (p < 0.05) and tended to lower F:G ratio (p = 0.07) compared with that of CON group from day 28 to 180 of age. The offspring pigs from MD group had greater serum IGF‐1 concentrations and expressions of hepatic IGF‐1 gene and muscular IGF‐1 receptor (IGF‐1r) protein at birth (p < 0.05), and greater hepatic IGF‐1 protein (p = 0.03) and muscular IGF‐1r gene expressions (p < 0.05) at slaughter, than that from the CON group. Moreover, the methylation at the promoter of IGF‐1 gene in the liver of newborn piglets and finishing pigs was greater in the MD group than that of the CON group (p < 0.05). In conclusion, maternal MD supplementation throughout gestation could enhance the birthweight and postnatal growth rate of offspring, associated with an increased expression of the IGF‐1 gene and IGF‐1r, as well as the altered DNA methylation of IGF‐1 gene promotor.     

Evaluation of two commercial PRRSV antibody ELISA kits with samples of known status and singleton reactors

Two commercial PRRSV ELISA kits (IDEXX and Bionote) were evaluated for their sensitivity and specificity using 476 PRRS-positive serum samples collected from 7 animal challenge experiments and 1,000 PRRS-negative sera. Both ELISA kits exhibited 100% sensitivity with sera collected 14 to 42 days post-infection, and the results from the kits were highly correlated (R²=0.9207). The specificity of IDEXX or Bionote kit was 99.9% or 99.7%, respectively. In addition, the Bionote ELISA kit was used to examine 100 sera that were determined to be falsely positive either by IDEXX 2XR or 3XR ELISA, and only 7 of these samples were found to be positive. These results indicate that both ELISA kits exhibited similar levels of sensitivity and specificity and would complement one another for the verification of false-positive samples.     

Feasibility analysis of NIR for detecting sweet corn seeds vigor

This paper explores the feasibility of particle-based detection and grading of seed vigor based on a self-built seed single-granulation device using near infrared spectroscopy (NIRS). Sweet corn with uniform kernel size was used for this study. The seed samples were divided into three types, they were normal seeds, artificially aged seeds and heat-damaged seeds. A 2-part spectral acquisition of each seed were performed, one for the collection of seeds that fall into the detection zone within the separation pipe, another was on the static platform, whose collection was performed on 5 faces of each seed. Partial least squares discriminant analysis (PLS-DA) was used to classify the original data of the seeds. In the 2 parts, the discriminant results of the unprocessed normal seeds and the artificial accelerated aging seeds, the untreated normal seeds and the heat-damaged seeds showed that classification accuracy was higher than 98%. The research indicates that the spectral data of different positions of seeds can reflect their activity information, and it is feasible to detect and classify seeds in real time in the detection area of the separation pipeline.     

粉条加工中添加石蜡的检测技术研究

【目的】探讨粉条加工过程中非法添加石蜡的测定方法,为食品监管提供保障。【方法】先以石蜡成品摸索石蜡测定的气相色谱质谱条件,再以石蜡成分C18H38和C24H50进行回收率和相对标准偏差试验。【结果】不同预处理方法中,超声萃取处理的C18H38和C24H50在粉条中的萃取回收率最高,分别为93.5%和91.0%;20min超声时间萃取粉条中烷烃成分较为适宜;所建立的粉条中石蜡含量测定方法的相对标准偏差为3.6～4.8,样品回收率均大于90.0%,达到定量检测要求。【结论】所建立的石蜡检测方法操作简单,测定结果准确可靠,可用于粉条中石蜡成分的定性及定量测定。