牛GDF9和BMP15基因遗传变异与双胎性状的关系研究

以生长分化因子9(Growth differentiation factor 9,GDF9)基因和骨形态发生蛋白15(Bone morphogenet-ic protein 15,BMP15)基因作为牛双胎性状的候选基因,研究了它们在鲁西牛、秦川牛、南阳牛和中国荷斯坦牛4个品种中的遗传变异,并在鲁西牛群体中研究了其多态位点与双胎性状的关系。结果表明:在鲁西牛中GDF9基因的3′UTR发现缺失突变,而其它3个品种中没有发现该突变。对鲁西牛群体中该多态位点与单、双胎性状之间进行卡方显著性检验表明,单胎牛群体与双胎牛群体基因型分布有极显著的差异(P=0.006),双胎牛群体的B等位基因频率明显大于单胎牛群体。通过生物信息学分析表明,突变体mRNA的二级结构与野生型相比总自由能值差异不大,但突变体mRNA翻译起始位点的二级结构稳定性明显大于野生型。在鲁西牛、南阳牛和秦川牛的BMP15基因中发现编码区第759~762位有GAAA 4个碱基存在缺失突变,但没有检测到突变纯合个体,中国荷斯坦牛中没有检测到该突变。卡方显著性检验表明单胎牛群体和双胎牛群体在该位点基因型组成差异不显著(P=0.947)。     

黄河中游多沙粗沙区近40年降水特征分析

本文采用黄河中游多沙粗沙区具有代表性的17个雨量站的近40年旬降水量资料,分析了其降水量变化的特点和分布规律。结果表明:多沙粗沙区降水量年内分布集中,季节差异大;区间降水分配不均匀,且可分为三种明显不同的类型。各区降水量近几年来都呈现出明显的减少趋势。     

Molecular characterization of <Emphasis Type="Italic">Phoma tracheiphila</Emphasis>, causal agent of Mal secco disease of citrus,in Israel

Mal secco disease of citrus caused by Phoma tracheiphila is a devastating disease in the Mediterranean basin. Susceptible citrus species include lemon, citron, lime and others. Trees attacked by the fungus show characteristic symptoms; the smallest twigs die first, followed by the larger branches. Eventually, the whole tree is killed. The symptoms are clear in the orchards but by the time they are visible the disease is already well established. The need for a sensitive, reliable and rapid diagnostic method for the early identification of the fungus in trees and fruit exists. We have developed a PCR-based method for the identification of P. tracheiphila from plant tissues including fruit. Any such method must take into account the genetic variability in the pathogen population. Molecular methods were used to compare different isolates of P. tracheiphila. This study found no significant differences between different isolates from different citrus species from different parts of Israel.     

Roles of stolbur phytoplasma and <Emphasis Type="Italic">Reptalus panzeri</Emphasis> (Cixiinae,Auchenorrhyncha) in the epidemiology of Maize redness in Serbia

Maize redness (MR), a disease causing midrib, leaf and stalk reddening and abnormal ear development in maize, has been reported from Serbia, Romania and Bulgaria for 50 years. Recent epiphytotics reduced yields by 40%–90% in southern Banat, Serbia. MR was recently associated with the presence of the stolbur phytoplasma, although the epidemiology of the disease remained unknown. Diseased fields in southern Banat were surveyed for potential vectors of the phytoplasma during 2005 and 2006, and high populations of Reptalus panzeri were found. In affected fields, 20% of the R. panzeri individuals and 85% of symptomatic maize plants carried the stolbur phytoplasma. When stolbur phytoplasma-infected R. panzeri were introduced into insect-free mesh cages containing healthy maize plants, midrib and leaf reddening developed on 48% of plants and stolbur phytoplasma was detected in 90% of the symptomatic plants. No symptoms or phytoplasma-positive plants were found in cages without insects. These data indicate that MR symptoms are associated with the stolbur phytoplasma. Reptalus panzeri is both abundant in affected fields and can transmit the stolbur phytoplasma, indicating the insect is likely to be a major vector of MR.     

‘Candidatus Phytoplasma australiense’ is the phytoplasma associated with Australian grapevine yellows, papaya dieback and Phormium yellow leaf diseases

Sequence comparisons and phylogenetic analysis of the 16S rRNA genes and the 16S/23S spacer regions of the phytoplasmas associated with Australian grapevine yellows, papaya dieback and Phormium yellow leaf diseases revealed minimal nucleotide differences between them resulting in the formation of a monophyletic group. Therefore, along with Australian grapevine yellows, the phytoplasmas associated with Phormium yellow leaf and papaya dieback should also be considered as Candidatus Phytoplasma australiense.     

公路路线方案优选中的多目标决策

本论述应用层次分析法对林区公路路线方案进行优化决策，从中确定最佳路线方案。以克服传统上使用定性分析法的一些不足，使结果更加科学合理。     

经济后发地区农村新型医疗保障体系模式研究——以江苏省宿迁市为例

以江苏省宿迁市农村为研究对象,分析了现阶段宿迁市农村医疗保障体系运行中存在的主要问题,研究设计一个符合我国经济欠发达地区农村居民需求的多层次新型医疗保障体系,对农村新型医疗保障体系的结构模式和各种制度政策进一步完善优化,并提出切实可行的政策措施,以期完善经济后发达地区农村医疗保障体系,满足农村居民医疗保障需求。     

适应不同成熟度大豆的差速脱粒滚筒性能试验与分析

针对南方地区大豆草谷比和未成熟豆荚占比高，造成收获机脱粒清选分离质量差、功耗大等问题，设计了一种前后两段组合且两段转速差可调的脱粒滚筒，研究了脱粒滚筒参数变化对豆荚和籽粒的能量、等效形变量等的影响。以脱粒齿类型、前段滚筒转速、两段滚筒转速差为影响因素，以破碎率、未脱净率和夹带损失率为评价指标，得到了差速与非差速脱粒滚筒的最优参数组合，并通过综合性能试验对比了两种脱粒滚筒的脱粒质量、作业油耗和工作效率。结果表明，差速脱粒滚筒最优参数组合是脱粒齿类型为纹杆齿-杆齿组合式脱粒齿，前段滚筒转速为450 r/min，两段滚筒转速差为150 r/min。此时，相较于传统的杆齿式非差速脱粒滚筒，脱粒质量更高，油耗降低了2.7 L/hm²，最大作业效率增大了10.35%。该研究能够为解决南方地区大豆联合收获机脱粒装置适应性问题提供依据。     

吉林林区社会养老保障制度改革研究

在大量调查和深入分析的基础上，揭示了吉林林区现行社会养老保障制度存在的问题，论证了深入进行社会养老保障制度改革的必要性，提出了改革和完善吉林林区社会养老保障制度的措施     

地膜覆盖下豆禾混播草地根系的动态研究

使用差额法连续分层次地对燕麦＋豌豆人工草地的根系在地膜覆盖条件下的生长发育动态进行了研究，结果表明：燕麦根系的58％分布浅，豌豆的77％根系分布在10～20cm深，两者混播后，其根系可有效地互补，且在地膜覆盖条件下互补性增强。同时地膜覆盖后，使根系的分布更浅，根量减少。