Effect of size reduction by freeze-milling on processing properties of beta-glucan oat bran

An effect of freeze-milling on processing properties of beta-glucan oat bran has been evaluated. A comparison with existing, patented methods of high molecular weight oat beta-glucan has been carried out. The new method employs raw material pre-treatment with freezing and milling in a hammer mill, resulting in significant reduction of particle size – 89% was between 80 and 50 μm in comparison with initial material when 79% were between 250 and 200 μm. Reduction of particle size also improved some process parameters of extraction technology – 30% improvement in fat removal during first stage of beta-glucan recovery was observed. The achieved pilot plant yield of product containing beta-glucan extraction was 64,03%, purity (ie. beta-glucan content), of achieved product was 84,4% and average molecular weight was about 69,500 g/mol.     

Production of inbred larvae through self‐fertilization using oocytes and cryopreserved sperm from the same individuals after sex reversal in eastern oyster Crassostrea virginica

The eastern oyster Crassostrea virginica can change sex which makes self‐fertilization possible if sperm can be cryopreserved. In this study, small (~1 year old) and large (~2–3 years old) oysters were biopsied for sperm collection. Survival of the biopsied oysters after 1 year was 50% for small oysters and 17% for large oysters. Oocytes were collected from sex‐reversed females, and self‐fertilized with cryopreserved sperm. Of the 24 cryopreserved samples, 14 individuals had ≤1% fertility when crossed with oocytes from unrelated females, indicating that the cryopreserved sperm had reduced fertility. The other 10 individuals had a fertility of 39 ± 25% when crossed with oocytes from unrelated females (non‐selfing), but showed a significantly lower success of self‐fertilization (12 ± 16%) (P = 0.008), while aliquots of the same oocytes had a fertilization of 83 ± 11% when crossing with fresh sperm. Larvae were produced at day 3 in the self‐fertilized families (12–94% of the fertilized oocytes), and survived to eyed‐larvae stage at days 11–14. Genotyping with 9 microsatellite markers confirmed that the larvae resulted from self‐fertilization in four families. This study demonstrated the feasibility of creating self‐fertilized inbred lines of oysters by use of non‐lethal sperm collection and cryopreservation.     

Evaluation of angler reporting accuracy in an off‐site survey to estimate statewide steelhead harvest

Accuracy of angler‐reported data on steelhead, Oncorhynchus mykiss (Walbaum), harvest in Idaho, USA, was quantified by comparing data recorded on angler harvest permits to the numbers that the same group of anglers reported in an off‐site survey. Anglers could respond to the off‐site survey using mail or Internet; if they did not respond using these methods, they were called on the telephone. A majority of anglers responded through the mail, and the probability of responding by Internet decreased with increasing age of the respondent. The actual number of steelhead harvested did not appear to influence the response type. Anglers in the autumn 2012 survey overreported harvest by 24%, whereas anglers in the spring 2013 survey under‐reported steelhead harvest by 16%. The direction of reporting bias may have been a function of actual harvest, where anglers harvested on average 2.6 times more fish during the spring fishery than the autumn. Reporting bias that is a function of actual harvest can have substantial management and conservation implications because the fishery will be perceived to be performing better at lower harvest rates and worse when harvest rates are higher. Thus, these findings warrant consideration when designing surveys and evaluating management actions.     

Variation in growth rates and aggressiveness of naturally occurring self‐fertile and self‐sterile isolates of the wilt pathogen Ceratocystis albifundus

Ceratocystis albifundus is the most important fungal pathogen of black wattle (Acacia mearnsii) grown in plantations in southern and eastern Africa. It is a homothallic fungus but also undergoes unidirectional mating type switching. As a result, the ascospore progeny can be either self‐fertile or self‐sterile. The only apparent difference between these mating types is the deletion of the MAT1‐2‐1 gene in self‐sterile isolates. There is some evidence suggesting that self‐sterile isolates grow more slowly than self‐fertile isolates, but this has not been tested rigorously. The aim of this study was to determine whether self‐sterile isolates are less fit by examining growth rate, relative germination rate and pathogenicity. Five self‐sterile isolates were generated from each of five self‐fertile isolates of C. albifundus and these 30 isolates were compared. The results showed that the self‐sterile isolates grew consistently slower and were less pathogenic than the self‐fertile isolates. The germination ratio of self‐fertile to self‐sterile isolates from single ascospores collected from the ascomata of five self‐fertile isolates was on average 7:3. This could be a consequence of the self‐sterile isolates having a lower germination rate. This observation, and the lower growth and pathogenicity levels, suggests that self‐sterile isolates are not likely to compete effectively in nature, raising intriguing questions regarding their role and value to C. albifundus and other fungi having a similar mating system.     

Validation of two models for self‐incompatibility in autotetraploid perennial ryegrass using high resolution melting‐based markers

Perennial ryegrass (Lolium perenne L.) displays a two‐locus gametophytic self‐incompatibility (SI) system that remains intact at the tetraploid level. Two models are plausible for SI in autotetraploids. In Model I: both alleles at the S locus and both at the Z locus in diploid pollen matching the female genotype results in incompatibility. In Model II: only one allele at S and one at Z locus in diploid pollen matching the female results in incompatibility. The goals were to determine which of the models best explains SI in our autotetraploid ryegrass population and to evaluate the efficiency of high‐resolution melting (HRM) genotyping for discriminating different iso‐allelic genotypes. The progeny of a cross between two autotetraploids was characterized with three HRM‐based markers co‐segregating with Z. Segregation ratios were used to make inferences about the mode of action of the SI system. The observed segregation differed significantly (P < 0.001) from the expected under Model I, but not from the expected under Model II (P = 0.463). Thus, Model II explains SI in this population, and HRM is an efficient tool to distinguish different iso‐allelic genotypic classes.     

4M-2型马铃薯联合收获机土薯分离运动仿真

采用ADAMS软件对马铃薯收获机虚拟样机抖动分离装置进行了运动仿真,研究了其运动规律,模拟了运动过程,明确了薯块在分离器上的运动机理,分析了薯块质心点的运动参数曲线.结果表明:分离器安装角为17°,抖动器抖动频率为8.89 Hz,长、短轴半径分别为69 mm、55 mm,马铃薯质心点的竖向平均速度大部分≤468mm.s-1、水平方向速度在1 342~1 530 mm.s-1范围内时,输送顺畅,可满足设计要求.     

Can the presence of a large conspecific improve the production and welfare of groups of smaller self‐feeder competent rainbow trout?

This study examined the production and welfare effects of including a large self‐feeder competent rainbow trout, Oncorhynchus mykiss (Walbaum) (~665 g) in groups of smaller self‐feeder competent conspecifics (~234 g). Costs and benefits were examined for both welfare (aggression, fin damage, condition and mortality) and production (self‐feeder utilization and growth). The 8‐week experiment used six groups of small trout; three treatment groups containing a large trout and three control groups. After 4 weeks the large fish were removed from treatment groups and added to control groups, thus reversing the treatments. Whilst it was thought that the presence of a larger fish would suppress aggression in smaller conspecifics this did not occur. In fact aggression was significantly (P = 0.036) higher when large trout were present during the first 4 weeks. No significant differences were found between other welfare indicators, self‐feeder utilization or production parameters. From a production and welfare perspective these results suggest that with the exception of initially increasing aggression larger fish do not represent a significant benefit or risk to smaller conspecifics being cultured in self‐feeder equipped tanks, when all fish are self‐feeder competent.     

水稻黑条矮缩病毒P91在烟草表皮细胞中自我互作并形成包涵体

水稻黑条矮缩病毒(Rice black streaked dwarf virus,RBSDV)是斐济病毒属的成员,由昆虫介体灰飞虱传播,能够在植物宿主和昆虫介体中复制。同其他斐济病毒成员一样,RBSDV的复制与装配是在细胞质病毒包涵体结构即毒质结构里进行的。RBSDV有10条基因组dsRNAs(S1—S10),其第9条片段(S9)的第一个阅读框(ORF)编码的蛋白P9 1是形成毒质结构的框架蛋白。将P9 1与绿色荧光蛋白(GFP)融合后,在本氏烟草的表皮细胞中单独表达,通过激光共聚焦扫描显微镜观察发现P9 1可以形成包涵体结构;利用双分子荧光互补(BiFC)实验证明了P9 1具有自我互作的能力,并形成包涵体结构。     

高校大学生就业竞争力的自我认知研究

为了更多地了解大学生就业竞争力的自我认知现状,对河北农业大学570名大学生进行了关于大学生就业状况的问卷调查,调查结果显示,大学生对自身就业竞争力的自我认知不足。针对这一现状,提出从加强大学生思想政治教育、职业生涯规划教育、就业指导等方面来提升大学生就业竞争力。     

大学生自我和谐与日常烦心事及其应对方式的关系研究

采用自我和谐、日常烦心事和应对方式问卷对300名大学新生进行调查。研究结果表明：①大学新生自我和谐处于中等程度;在日常烦心事中,人际关系、学业疏离、时间压力对学生影响较大;解决问题和求助是学生常采用的应对方式。②不同性别和生源地学生在自我和谐、日常烦心事和应对方式部分维度上存在显著差异。③自我和谐及各维度与日常烦心事和...