表型同型交配群体的Shannon信息熵和互信息

应用信息论方法研究了在表型同型交配下一对等位基因群体的基因型信息熵和互信息。在表型同型交配下,从随机交配下的平衡状态开始,群体的基因型信息熵逐代减少,但这种减少的趋势越来越慢,最终趋向于零。随着基因型信息熵的减少,群体的遗传多样性程度也越来越小。在表型同型交配下,群体的配子间互信息逐代增加,但这种减少的趋势越来越慢,最终趋向于零。配子间互信息的增加说明,配子间的信息交流程度逐代增加,两性配子间的信息关联程度越来越密切,而这用表型信息关联系数反映会更好。最后应用Matlab软件进行了数学模拟,直观验证了所得的结论。     

根结线虫在中国的新纪录种——西班牙根结线虫(Meloidogyne hispanica Hirschmann)

 A root-knot nematode, Meloidogyne hispanica Hirschmann, was first described and illustrated from roots of papaya in Danzhou, Hainan province in China. The perineal pattern of female was characterized by oval shaped to rectangular with a low dorsal arch; dorsal striae varied from fine and wavy to coarse; lateral lines forked with fringe-like striae between lines and phasmidial ducts distinctly appeared. Male had high and rounded head region with labial disc and medial lips fused to form elongate lip structures. Second-stage juve-nile had distinct body annules and stylet with rounded, posteriorly sloping knobs, and the tail terminus was slender with indistinct hyaline. This Chinese new record of M. hispanica had a unique esterase phenotype (S2-M1) which was different from that of other Meloidogyne species.     

老芒麦衰老过程形态特征变化规律及对养分添加的响应

试验以青藏高原青海省高寒草地中广泛分布和退化草地补播改良中的常用牧草品种-‘青牧1号’老芒麦为研究对象,在青藏高原东北部,青海湖湖东地区设置1龄到6龄老芒麦自然生长田,6龄老芒麦施肥田和老芒麦连续施肥田（6年）的3个处理,测定老芒麦地上生物量和穗部特征并进行比较分析。结果表明：青牧1号老芒麦2龄和3龄地上生物量较高,3龄后逐年降低。青牧1号老芒麦地上生物量变化情况,可以分为4个阶段,1龄期,2~3龄期,4~5龄期和6龄期。老芒麦单穗重从2龄到5龄逐渐增加,6龄显著性降低。青牧1号老芒麦从2龄到5龄,单株穗重占比逐渐升高,6龄开始降低。6龄田施用氮肥和磷肥均显著提高了老芒麦地上生物量,氮肥增产效果优于磷肥。高氮（N₇₅）处理下6龄老芒麦地上生物量最高。6龄青牧1号老芒麦单穗重在N₆₀处理下最高。长期施肥可有效提高老芒麦地上生物量,N₆₀P₇₅处理下地上生物量最高,在N₇₅P₇₅处理下6龄老芒麦单穗重最高。长期不施肥,6龄老芒麦茎重比例最高。N₄₅P₉₀长期施肥处理下,茎秆重量比例下降,穗重和叶重比例相对增加明显。N₆₀P₉₀和N₇₅P₇₅长期施肥处理下,也可有效提高单株老芒麦穗重的比例。     

孕期应激对绵羊子代表型编程效应研究进展

家畜孕期应激对子代行为、生理和神经方面有着复杂的影响,这种影响可以持续到子代成年甚至跨代遗传。家畜孕期管理不当会对母体产生应激,使母体及其子代的生长、健康和福利受损,从而影响家畜的经济价值。本文以绵羊孕期应激模型和人工合成糖皮质激素模拟应激模型的试验结果为切入点,系统总结了绵羊孕期应激对子代表型的影响,并讨论了研究结果异同的可能原因。研究发现,绵羊孕期应激可以影响子代出生体重、调节子代下丘脑—垂体—肾上腺轴发育、影响子代行为模式和认知能力、改变子代基因表达和大脑形态,并且母体糖皮质激素水平是决定子代表型变化的主要因素。未来研究方向应该侧重于绵羊孕期应激对子代基因表达、免疫功能、生产性能和母性行为的影响,以及不同妊娠时期母体应激的比较研究、对子代影响的连续研究和探讨孕期应激不良编程的应对策略研究。     

核桃亲子鉴定方法的建立

 【目的】针对核桃育种中父本不清、亲本混淆问题,建立简便快捷高效的核桃亲本鉴定方法,也为其它林木和果树品种亲本鉴定提供参考。【方法】以‘鲁果2号’为鉴定材料,采用表型性状和SSR标记的方法对‘鲁果2号’及其可能的亲本进行亲子分析。【结果】表型性状方法统计的8对坚果性状在各品种间差异很小,不能鉴定出子代亲本;SSR分型检测出疑似亲本中只有‘上宋6号’和‘鲁香’与子代‘鲁果2号’的等位基因遗传符合孟德尔遗传规律,其累积RCP（亲子关系概率）为99.997%,‘slz-40’与已知亲本鉴定结果与实际相符。【结论】‘上宋6号’和‘鲁香’是‘鲁果2号’的亲本,SSR分型技术较好地鉴别出了‘鲁果2号’的亲本,为其它林木和果树品种寻找和鉴别亲本,提供有效手段。     

部分表型交配群体的信息熵

研究了在世代交替中群体总有50%的个体表型同型交配、50%的的个体随机交配的大盂德尔群体,推得各世代基因型频率分布、母子间基因型频率分布,给出各世代基因型信息熵、母子间基因型联合信息熵的算式,并证明二者随世代交替逐渐减少,最终趋于定值,群体最终达到一种远离Hardy-Weinberg平衡的非平衡定态.模拟结果验证了所得...     

Genetic diversity, aggressiveness and metalaxyl sensitivity of Pythium aphanidermatum populations infecting cucumber in Oman

Seventy three isolates of Pythium aphanidermatum obtained from cucumber from four different regions of Oman and 16 isolates of muskmelon from the Batinah region in Oman were characterized for aggressiveness, sensitivity to metalaxyl and genetic diversity using AFLP fingerprinting. Twenty isolates of P. aphanidermatum from diverse hosts from different countries were also included in the study. Most isolates from Oman were found to be aggressive on cucumber seedlings and all were highly sensitive to metalaxyl (EC₅₀ < 0·80 µg mL^?1). Isolates from cucumber and muskmelon were as aggressive as each other on both hosts (P > 0·05), which implies a lack of host specialization in P. aphanidermatum on these two hosts in Oman. AFLP analysis of all isolates using four primer–pair combinations resolved 152 bands, of which 61 (~40%) were polymorphic. Isolates of P. aphanidermatum from Oman and other countries exhibited high genetic similarity (mean = 94·1%) and produced 59 different AFLP profiles. Analysis of molecular variance indicated that most AFLP variation among populations of P. aphanidermatum in Oman was associated with geographical regions (F_ST = 0·118; P < 0·0001), not hosts (F_ST = –0·004; P = 0·4323). These data were supported by the high rate of recovery (24%) of identical phenotypes between cucumber and muskmelon fields in the same region as compared to the low recovery (10%) across regions in Oman, which suggests more frequent movement of Pythium inoculum among muskmelon and cucumber fields in the same region compared to movement across geographically separated regions. However, recovering clones among regions and different countries may imply circulation of Pythium inoculum via common sources in Oman and also intercontinental spread of isolates.     

The wheat stem rust pathogen in the central region of the Russian Federation

A total of 387 isolates of Puccinia graminis f. sp. tritici (Pgt) collected in the central region of the Russian Federation from 2000 to 2009 was analysed with North American differential sets comprising 16 genotypes for samples of 2000–2006 and 20 genotypes for samples from 2007–2009. Forty‐five races were identified. The race composition of the local population underwent changes during this period. Race MKBT was the predominant race in the earlier years, but TKNT and TKNTF were in the majority later. During 2000–2009 there were no stem rust epidemics in the region. It was assumed that the local pathogen population cycled on wild grasses (including Elytrigia, Agropyron, Festuca, Dactylis, Phleum and Lolium spp.) and not only on wheat. The existence of host communities of wheat stem rust was supported by random amplified polymorphic DNA (RAPD) markers produced with high‐GC primers. The local population of Pgt was considered to be sexual based on the relatively high diversity of races isolated from various hosts and the absence of correlation between virulence attributes and molecular markers.     

Understanding pathogen population structure and virulence variation for efficient resistance breeding to control cucurbit powdery mildews

Cucurbit powdery mildew (CPM) is caused most frequently by well-differentiated obligate erysiphaceous ectoparasites Golovinomyces orontii and Podosphaera xanthii, which vary in their ecology and virulence. All economically important cucurbit crops host both of these CPM species. Breeding of cucurbits for CPM resistance is highly important worldwide, but adequate knowledge of CPM species determination, as well as virulence structure, population dynamics, and spatiotemporal variation of these pathogens, has not yet been achieved. New tools have been developed to enhance research on CPM virulence variation for more efficient breeding and seed and crop production. A set of differential genotypes of Cucumis melo, with high differentiation capacity, may contribute substantially to understanding of variation in CPM virulence at both individual and population levels. Long-term observations (2001–2012) of CPM pathogens in the Czech Republic were used to analyse virulence variation within and among annual CPM populations and demonstrate the utility of recently developed tools for studying species variability and virulence variation of CPM pathogens worldwide. Detailed analyses of diversity and spatiotemporal fluctuations in the composition of CPM populations provide crucial information for shaping breeding programmes and predicting the most effective sources of race-specific resistance. The primary aim of this work was to create a uniform framework for determination of CPM species structure and diversity, virulence phenotypes, virulence and phenotype frequencies, phenotype complexity, dynamics, and variation within and among CPM populations. In addition, practical advice is presented on how to select the most relevant data and interpret them for use in cucurbit resistance breeding.     

Practical implications of using non-relational databases to store large genomic data files and novel phenotypes

The objective of our study was to provide practical directions on the storage of genomic information and novel phenotypes (treated here as unstructured data) using a non-relational database. The MongoDB technology was assessed for this purpose, enabling frequent data transactions involving numerous individuals under genetic evaluation. Our study investigated different genomic (Illumina Final Report, PLINK, 0125, FASTQ, and VCF formats) and phenotypic (including media files) information, using both real and simulated datasets. Advantages of our centralized database concept include the sublinear running time for queries after increasing the number of samples/markers exponentially, in addition to the comprehensive management of distinct data formats while searching for specific genomic regions. A comparison of our non-relational and generic solution, with an existing relational approach (developed for tabular data types using 2 bits to store genotypes), showed reduced importing time to handle 50M SNPs (PLINK format) achieved by the relational schema. Our experimental results also reinforce that data conversion is a costly step required to manage genomic data into both relational and non-relational database systems, and therefore, must be carefully treated for large applications.