仔猪雷极氏普罗菲登斯菌的分离鉴定及系统进化分析

为了解猪雷极氏普罗菲登斯菌(P.rettgeri)的生物学特性、致病性及16SrRNA基因系统进化关系,从发生严重腹泻、血便的哺乳仔猪群的内脏器官中分离到1株病原菌,根据形态特征、培养特性、生化特性、16SrRNA基因序列分析鉴定为P.rettgeri。小鼠攻毒试验证实,该分离菌株对试验小鼠有较强致病力,哺乳仔猪回归试验可复制出与临床上相似的典型症状,并从发病死亡小鼠及哺乳仔猪中分离到攻毒菌株。系统进化分析表明,分离菌株与雷极氏普罗菲登斯菌系统进化关系最为密切,其16SrRNA基因序列与雷极氏普罗菲登斯菌代表菌株的同源性在97.3%~99.6%之间。药敏试验结果表明,分离菌株对头孢哌酮钠、头孢噻肟钠、头孢曲松钠、头孢唑啉、头孢呋肟、头孢吡肟、阿莫西林、链霉素、氨曲南、诺氟沙星、左氟沙星、恩诺沙星、卡那霉素、氨苄青霉素、米诺环素、链霉素、阿米卡星等多数药物敏感。首次报道了雷极氏普罗菲登斯菌可以引起哺乳仔猪严重腹泻,提示在仔猪腹泻中应注意该菌感染的诊断、监测和防控。     

Impact of Endocrine‐Disrupting Chemicals on Reproductive Function in Zebrafish (Danio rerio)

The prevalence of endocrine‐disrupting chemicals (EDCs) in the aquatic environment has been associated with the wide detection of alterations in the development and physiology of vertebrates. Zebrafish, as a model species, has been extensively used in toxicological research. In this review, we focus on recent published evidence of the harmful effects of EDCs on reproductive function in zebrafish, including skewed sex ratio, immature gonads, diminished sexual behaviour, decreased sperm count, reduced spawning and fertilization. These impairments mostly result from disruption to sex‐steroid hormones induced by endocrine disruptors. We also discuss other effects of exposure to EDCs. In EDC exposure research, despite incomplete assessments of altered gonad histopathology and sexual behaviour, these present potential effective biomarkers or pathways for evaluating the reproductive function in zebrafish on EDC exposure. To date, the pernicious effects of some EDCs on the reproductive performance in laboratory zebrafish are well understood; however, similar alterations remain for further determination in wild‐type fish and more kinds of EDCs. More studies should be performed under established scientific regulatory criteria to investigate the impact of EDCs on reproduction in zebrafish. Moreover, further research is required to explain the definite mechanism of sexual differentiation, which helps in understanding the shift of sexual phenotype with EDC exposure.     

Impact of relationships between test and training animals and among training animals on reliability of genomic prediction

One of the factors affecting the reliability of genomic prediction is the relationship among the animals of interest. This study investigated the reliability of genomic prediction in various scenarios with regard to the relationship between test and training animals, and among animals within the training data set. Different training data sets were generated from EuroGenomics data and a group of Nordic Holstein bulls (born in 2005 and afterwards) as a common test data set. Genomic breeding values were predicted using a genomic best linear unbiased prediction model and a Bayesian mixture model. The results showed that a closer relationship between test and training animals led to a higher reliability of genomic predictions for the test animals, while a closer relationship among training animals resulted in a lower reliability. In addition, the Bayesian mixture model in general led to a slightly higher reliability of genomic prediction, especially for the scenario of distant relationships between training and test animals. Therefore, to prevent a decrease in reliability, constant updates of the training population with animals from more recent generations are required. Moreover, a training population consisting of less‐related animals is favourable for reliability of genomic prediction.     

Astaxanthin Normalizes Epigenetic Modifications of Bovine Somatic Cell Cloned Embryos and Decreases the Generation of Lipid Peroxidation

Astaxanthin is an extremely common antioxidant scavenging reactive oxygen species (ROS) and blocking lipid peroxidation. This study was conducted to investigate the effects of astaxanthin supplementation on oocyte maturation, and development of bovine somatic cell nuclear transfer (SCNT) embryos. Cumulus–oocyte complexes were cultured in maturation medium with astaxanthin (0, 0.5, 1.0, or 1.5 mg/l), respectively. We found that 0.5 mg/l astaxanthin supplementation significantly increased the proportion of oocyte maturation. Oocytes cultured in 0.5 mg/l astaxanthin supplementation were used to construct SCNT embryos and further cultured with 0, 0.5, 1.0 or 1.5 mg/l astaxanthin. The results showed that the supplementation of 0.5 mg/l astaxanthin significantly improved the proportions of cleavage and blastulation, as well as the total cell number in blastocysts compared with the control group, yet this influence was not concentration dependent. Chromosomal analyses revealed that more blastomeres showed a normal chromosomal complement in 0.5 mg/l astaxanthin treatment group, which was similar to that in IVF embryos. The methylation levels located on the exon 1 of the imprinted gene H19 and IGF2, pluripotent gene OCT4 were normalized, and global DNA methylation, H3K9 and H4K12 acetylation were also improved significantly, which was comparable to that in vitro fertilization (IVF) embryos. Moreover, we also found that astaxanthin supplementation significantly decreased the level of lipid peroxidation. Our findings showed that the supplementation of 0.5 mg/l astaxanthin to oocyte maturation medium and embryo culture medium improved oocyte maturation, SCNT embryo development, increased chromosomal stability and normalized the epigenetic modifications, as well as inhibited overproduction of lipid peroxidation.     

Assessment of caecal parameters in layer hens fed on diets containing wheat distillers dried grains with solubles

1. There is much interest in quantifying the nutritional value of UK wheat distillers dried grains with solubles (W-DDGS) for livestock species. A study was designed to evaluate caecal parameters (pH, short chain fatty acids (SCFAs) and bacterial diversity) in layer hens fed on balanced diets containing graded concentrations of W-DDGS.

2. A total of 32 layer hens (Bovans Brown strain at 27 weeks of age) were randomly allocated to one of 4 dietary treatments containing W-DDGS at 0, 60, 120 or 180 g/kg. Each treatment was fed to 8 replicate individually housed layer hens over a 5-d acclimatisation period, followed by a 4-week trial. Individual feed intakes were monitored and all eggs were collected daily for weeks 2, 3 and 4 of the trial, weighed and an assessment of eggshell “dirtiness” made. All hens were culled on d 29 and caecal pH and SCFAs measured. Polymerase chain reaction denaturing gradient gel electrophoresis of the bacterial 16 S rDNA gene was used to assess total bacterial diversity of luminal caecal content from hens fed the 0 and 180 g W-DDGS/kg diets. Unweighted pair group method with arithmetic mean (UPGMA) dendrograms were generated from DGGE banding patterns.

3. Increasing W-DDGS dietary concentrations resulted in a more acidic caecal environment. Caecal SCFAs were unaffected by diet aside from a quadratic effect for molar proportions of isobutyric acid. Diversity profiles of the bacterial 16S rRNA gene from luminal caecal contents were unaffected by W-DDGS inclusion.

4. The results of the current study suggest that W-DDGS can be successfully formulated into nutritionally balanced layer diets (supplemented with xylanase and phytase) at up to 180 g/kg with no detrimental effects to the caecal environment.

     

Genetic characterization of bovine viral diarrhea virus strains in Beijing,China and innate immune responses of peripheral blood mononuclear cells in persistently infected dairy cattle

To acquire epidemiological data on the bovine viral diarrhea virus (BVDV) and identify cattle persistently infected (PI) with this virus, 4,327 samples from Holstein dairy cows were screened over a four-year period in Beijing, China. Eighteen BVD viruses were isolated, 12 from PI cattle. Based on genetic analysis of their 5''-untranslated region (5''-UTR), the 18 isolates were assigned to subgenotype BVDV-1m, 1a, 1d, 1q, and 1b. To investigate the innate immune responses in the peripheral-blood mononuclear cells of PI cattle, the expression of Toll-like receptors (TLRs), RIG-I-like receptors, interferon-α (IFN-α), IFN-β, myxovirus (influenza virus) resistance 1 (MX1), and interferon stimulatory gene 15 (ISG15) was assessed by qPCR. When compared with healthy cattle, the expression of TLR-7, IFN-α, and IFN-β mRNA was downregulated, but the expression of MX1 and ISG-15 mRNA was upregulated in PI cattle. Immunoblotting analysis revealed that the expression of interferon regulatory factor 3 (IRF-3) and IRF-7 was lower in PI cattle than in healthy cattle. Thus, BVDV-1m and 1a are the predominant subgenotypes in the Beijing region, and the strains are highly divergent. Our findings also suggest that the TLR-7/IRF-7 signaling pathway plays a role in evasion of host restriction by BVDV.     

Daily variation in body mass and thermoregulation in male Hwamei(Garrulax canorus) at different seasons

Background: Acclimatization to winter conditions is an essential prerequisite for survival of small passerines of the northern temperate zone. In the present study, we measured diurnal variations in body mass, body temperature and basal metabolic rate(BMR) for seasonally acclimatized Hwameis(Garrulax canorus).Methods: Body mass was determined with a Sartorius balance. Metabolic rates of Hwameis were measured with an open-circuit respirometry system.Results: Body masses varied with time of day and were higher in daytime for Hwameis in both summer and winter, and body masses in winter were higher compared to that in summer. Body temperatures of Hwameis were higher in daytime, and the summer acclimatized birds had significantly higher body temperatures compared to the winter acclimatized birds. BMRs of Hwameis were significantly higher during the daytime compared to the nighttime of the daily cycle in both summer and winter, and Hwameis in winter had significantly higher BMRs than that in summer.Conclusions: This result showed that Hwameis rely mostly on metabolic capacity to maintain their body temperature in cold weathers, and Hwameis exhibited daily and seasonal flexibility in morphology and physiology which is important under changing environmental conditions.     

松毛虫早期灾害点遥感监测研究初报

松毛虫早期灾害点遥感监测研究初报武红敢，黄建文，乔彦友（中国林业科学研究院资源信息所北京１００００１）严小君，陈林洪（浙江省江山市森林防疫站江山３２４１００）关键词松毛虫害，ＴＭ数据，影像，监测松毛虫为我国最为严重的森林害虫［１］。几十年来，各级政府...     

思茅松研究现状的探讨

本文从区系地理、生物特性、生态特点和开发利用等方面对思茅松的研究现状和存在问题作了系统的总结。认为思茅松是个重要的森林树种、在起源及分布上都与云南松和卡西亚松有联系，从理论到生产实践，都需要开展深入细致的研究。     

苌楚鸠蝠蛾的生物学特性及防治研究

苌楚鸠蝠蛾Ｐｈａｓｓｕｓ ａｃｔｉｎｉｄｉａｅ Ｙａｎｇ ｅｔ Ｗａｎｇ是福建近年来严重为害猕猴的一种新的蛀干害虫。我们于１９８４－１９８９年在建宁县猕猴桃试验站进行研究。该虫一年一代，以卵在树兜的地面越冬，幼虫为害猕猴桃植株韧皮部和髓部，外部形成虫屑包，内部形成蛀道，阻滞养分和水分的正常输送，轻者枝叶发黄，重者风折枯死。除选用抗虫品种外，采用２．５％溴氰菊脂１∶５０００液灌注；９０％敌百虫晶体１