歙县许村方言异读及音变现象研究

方言存在异读是一种普遍现象,从歙县许村方言[1]的实际情况看,其异读情况主要有四种表现形式：一是文白异读,二是元音内部屈折变化,三是变调,四是在语音发展中产生的合音现象。而音变则是在语流中由于音节的相互影响而产生的语音变化,从许村方言看,主要是清入与平、上、去三声结合而产生的变化。严格意义上说,它不属于异读,是与异读有本质区别的语音变化形式。对于这两种现象的研究,对于揭示方言语音与中古音韵的联系具有一定的意义。尤其是方言语音内部元音的屈折变化的研究,对于中古汉语是否存在形态变化更具有一定的理论意义。     

水稻谷氨酰胺合成酶同工型基因转录表达量与启动子结构关系分析

研究选用籽粒蛋白质含量差异显著的5个品种(系),比较分析品种间GS同工型基因在灌浆过程中籽粒和叶片表达特性及启动子序列与结构特点。结果表明,不同品种间OsGS同工型基因表达量差异显著;OsGS1;1和OsGS1;2基因在籽粒和叶片中大量表达;OsGS1;3和OsGS2基因分别仅在籽粒和叶片中大量表达;在灌浆过程中籽粒和叶片中OsGS同工型基因m RNA表达量均呈单峰曲线变化,灌浆前期m RNA表达量平稳升高,中期出现峰值,后期快速降低,且高蛋白质含量品种m RNA表达量高于低蛋白质含量品种。籽粒蛋白质含量差异显著品种间OsGS同工型基因启动子序列同源性高达99%以上;品种间有性杂交子代OsGS同工型基因启动子序列可发生碱基变化,但启动子核心元件无变化。在调控元件数量和功能上OsGS同工型基因启动子保守性很强,启动子在结构和功能上不易发生遗传变异,籽粒OsGS同工型基因m RNA表达量变化受OsGS基因启动子调控影响较小。     

犬细小病毒2型变异株对高母源抗体犬的致病性

为了探究CPV-2变异株的致病性,用CPV-2a和CPV-2b野毒株,分别攻击犬细小病毒(CPV-2)高母源抗体(MDA)幼犬,根据犬临床症状,组织病理学,粪便排毒和血清抗体应答等指标,评价高母源抗体(HI滴度≥1∶160)对不同CPV病毒变异株的保护作用。结果表明, CPV-2a和CPV-2b攻毒后引起明显临床症状,攻毒后3～6 d粪便中CPV排毒。感染犬的组织样品经PCR检测表明,CPV-2a/2b病毒广泛分布。组织病理学分析表明,CPV-2a/2b感染引起肠道黏膜出血。研究表明,CPV-2高母源抗体对CPV-2a/2b变异株攻击不能提供有效保护,有必要开发CPV变异株的新型疫苗。     

鸡传染性法氏囊病病毒地方流行毒株的免疫原性

从河北省一些发病鸡场分离到JD1～JD10共10株鸡传染性法氏囊病病毒(IBDV)毒株,用IBD标准阳性血清以琼扩试验进行了初步鉴定.并进行了IBDV分离物及其鸡胚适应毒免疫原对标准强毒IBDV-BC6/85株免疫保护试验,D78弱毒疫苗对IBDV各分离毒株的免疫保护试验以及分离毒株间交互免疫保护试验.结果表明,D78疫苗对JD2,JD5和JD10 IBDV分离株的保护率较低,分别为40%、50%和60%.分离毒株JD5、JD2及其鸡胚传代物E-JD2对强毒株的免疫保护率可达100%.交互免疫保护试验表明,JD2对其余各分离株的免疫保护指数达到80%以上,对标准强毒株和地方分离株均可产生有效免疫保护.     

甘蔗DNA导入玉米自交系性状变异的研究

采用花粉管通道法将甘蔗DNA导入普通玉米自交系,获得了变异植株,从中选出优良变异株,经3代自交观察,在D3代各农艺性状趋于稳定.对其主要农艺性状进行方差分析和D3代植株的叶绿素含量等生理生化分析,从中选出优良株系20-5000①和20-500②,其叶绿素、可溶性糖、蛋白质含量均比对照提高,可为今后玉米杂交育种提供中间材料.     

盐度对条斑紫菜体细胞生长发育的影响及耐低盐度变异体的初步观察

盐度对条斑紫菜体细胞的生长发育有明显的影响。盐度在19.6—32.8‰之间,体细胞生长发育正常;但超过32.8或低于19.6‰,体细胞成活率均下降,发育速度明显减慢。适当剂量的紫外线能促进体细胞苗生长,且可提高体细胞后代对高盐度和低盐度的忍耐力,同时获得少量能在低盐度下生长的变异体。刚酶解出的体细胞在高盐度下培养1天,然后逐渐降低盐度,可获得较高的成活率。     

Main environmental drivers of abundance, diversity and community structure of comammox Nitrospira in paddy soils

The recently discovered complete ammonia oxidizers comammox Nitrospira contain clades A and B that can establish an independent one-step nitrification process; however, little is known about their environmental drivers or habitat distributions in agricultural soils. Previous studies on comammox Nitrospira in paddy soils have mainly focused on small-scale samples, and there is a lack of multisite research on comammox Nitrospira in paddy soils. In this study, we conducted a survey of 36 paddy soils to understand the community structure, abundance, and diversity of comammox Nitrospira and the degree to which they are affected by environmental factors at a large scale. Comammox Nitrospira were found to be widely distributed among the paddy soils. The abundance of comammox Nitrospira clade A was mostly lower than that of clade B, whereas its diversity was mostly higher than that of clade B. Correlation analysis showed that multiple factors affected (P < 0.05) the abundance of comammox Nitrospira, including soil pH, organic matter, total carbon, and total nitrogen, latitude, mean annual temperature, and mean annual precipitation. Moreover, there was a clear relationship between the comammox Nitrospira community and habitat, indicating that some amplicon sequence variants (ASVs) had a unique dominant position in specific habitats. Phylogenetic analysis showed that the ASVs of comammox Nitrospira clade A clustered with the known sequences in the paddy soils and were significantly different from the known sequences in other habitats, which may be related to the unique paddy field habitat. In contrast, comammox Nitrospira clade B showed no clear habitat dependence. These results support the wide distribution and high abundance of comammox Nitrospira in paddy soils and provide novel insights into nitrogen cycling and nutrient management in agricultural ecosystems.