豆科树种根瘤菌共生体系研究进展

本文根据国内外有关豆科树种根瘤菌共生固氮研究现状,结合作者几年来的工作,对豆科树种的结瘤情况进行综述;对绝大多数苏木亚科树种既不结瘤,又不固氮的原因,以及豆科树种根瘤菌的分类地位和这一共生体系的其他性状,也进行了扼要的评述。     

油菜籽粒干物质来源的研究

本试验采用分部位去叶、遮光、环割果柄和测定茎枝的干物质积累等方法,研究了油菜的光合产物和贮藏物质对籽粒产量的影响,结果表明:(1)角果的光合产物是籽粒产量的主要来源,占2/3左右,其中果喙的光合产物约占籽粒产量的8％。(2)茎枝的光合产物对产量的贡献占13.5％,其中花序轴供给约5％。(3)茎枝中的贮藏物质对籽粒的灌浆结实作用较小,占10％以下。(4)叶片的光合产物直接用于籽粒灌浆结实的量很少,约占10％;它主要是通过影响植株、角果和内部籽粒的正常生长发育而影响产量。(5)油菜高产栽培的首要问题是调节结角层结构,使之处于良好的环境条件下,就个体而言,并不要求植株过分粗大。     

Directed evolution and characterization of a novel D-pantonohydrolase from Fusarium moniliforme

D-Pantonohydrolase has attracted increasing attention as a biocatalyst for stereospecific production of D-pantoic acid. The Fusarium moniliforme D-pantonohydrolase was selected for directed evolution through error-prone Polymerase Chain Reaction (PCR) combined with DNA shuffling for improved activity and pH stability using a convenient two-step high-throughput screening method based on the product formation and pH indicator. After three sequential error-prone PCRs and two rounds of DNA shuffling followed by screening, about 60 positive mutants were produced and a best mutant, Mut H-1287, with improved activity and pH stability was obtained. As compared to wild-type D-pantonohydrolase, Mut H-1287 showed a 10.5-fold higher specific activity; moreover, it could retain 85% of its original activity after incubation under low pH. Gene analysis indicated that the Mut H-1287 had D63H, K118Q, and V241I substitutions. The wild-type and evolved D-pantonohydrolase (Mut H-1287) was purified in three steps. The activities and characteristics of purified wild-type and evolved D-pantonohydrolase were also studied and compared.     

杨树杂交品种汉杨2号、汉杨3号、汉杨8号的选育初报

经过12年研究,选育出"汉杨2号"(鲁山杨×圣山杨)、"汉杨3号"(I-69杨×鲁山杨)、"汉杨8号"(圣山杨×鲁山杨)等3个杨树杂交新品种,其5 a生单株材积达到0.218 24 m3,0.241 3 m3,0.218 2 m3,其遗传增益为15.18%,26.08%,15.18%;通过初步试验结果,将进一步开展区域造林试验和推广应用。     

橡胶树四种有机肥肥效试验

通过2006-2007年两年对橡胶树品种RRIM600、GT1的4种有机肥肥效试验结果:千州有机—无机复混肥处理的两个橡胶树品种的干胶含量显著高于生产常规施肥(对照)和其它肥料处理;RRIM600的平均刀次干胶产量显著高于生产常规施肥(对照)和其他肥料处理。     

Effects of excessive selenium supplementation to diet contaminated with deoxynivalenol on blood phagocytic activity and antioxidative status of broilers

This study examined the effects of excessive dietary supplementation with organic selenium on phagocytic activity and antioxidative status of chickens for fattening fed diet contaminated with deoxynivalenol (DON). Sixty chickens of Ross 308 hybrids were at day of hatching divided into four groups with 15 birds in each. The background DON dietary levels in both negative and positive control groups were 0.2 mg/kg. The complete feed for positive control group was supplemented with Se dose 1 mg/kg in the form of Se-yeast. Group 3 was fed diet with DON level 3 mg/kg while diet for group 4 combined DON level 3 mg/kg with a excessive supplement of Se-yeast (Se dose 1 mg/kg). After 6 weeks of dietary intake, six randomly-chosen chickens from each group were sampled. Feeding of contaminated diet resulted in significantly reduced blood phagocytic activity (19.5 ± 1.1% in the negative control vs. 12.8 ± 0.8% in the DON-treated group, p < 0.05). Se-yeast supplemented to the DON contaminated diet prevented suppression of phagocytic activity. Dietary intake of DON at levels 3 mg/kg did not influence the plasma α-tocopherol level while excessive dietary Se dose reduced it in both Se supplemented groups. Neither the birds of DON-treated group nor the birds from group 4 with DON and Se-yeast showed any response in plasma γ-glutamyltransferase (GGT) activity. Subtoxic dietary level of DON significantly increased the activity of glutathione peroxidase (GPx) in the duodenal mucosa, while additional Se supplementation prevented such a response to mycotoxin. On the other hand, both Se supplemented groups showed significantly elevated GPx activities in blood, liver and kidney, (p < 0.05). The results suggest a potential ability of excessive supplementation of organic selenium to prevent the blood phagocytic activity suppression and changes in GPx activity in duodenal tissue induced in broilers by subtoxic dietary levels of DON.     

鸽感染鸡白痢沙门氏菌的诊断及药敏试验

无菌取病鸽的心脏、肝脏、肺脏、脾脏及肾脏等组织病料,进行细菌的分离培养与鉴定,结合临床症状和剖解病变,确诊病鸽为鸡白痢沙门氏菌感染。对分离菌株进行药敏试验,该菌对丁胺卡那、庆大霉素等敏感。     

做好气象微博客户服务的初步探讨与实践

笔者通过对气象微博的服务特点和开展情况的初步探讨,提出了针对气象微博在公共服务方面的发展建议。     

论林业合作经济组织在林业中的作用——以辽宁省抚顺市林业经济组织发展现状为依据

通过林业经济合作组织的产生、发展和现状的分析,探讨其在林业中的作用及其对林业的影响,以开拓读者的思路,求得读者对林业经济合作组织的关注。     

认清农村基本特征，促进社会道德建设——对当代农村社会主义核心价值建设的思考

三十年的改革开放加速了中国农村社会的转型和农民精神生活的深层变革，使当代中国农村社会具有了一些新的特征，表现为农村社会成份的混合性、农村社会成员个体属性的模糊性、农村社会信息传播的复杂性、农村生活方式的多元性和社会道德选择与建设的功利性等。这一切都使农村地区社会主义核心价值建设面临着新的挑战。