红富士苹果芽变系DNA甲基化研究

以35份富士苹果(Malus×domestica Borkh.‘Fuji’)芽变材料为试材,利用甲基化敏感扩增多态性(Methylation Sensitive Amplified Polymorphism,MSAP)分析和UPGMA聚类方法,对其基因组甲基化修饰水平、变异模式以及表观遗传变异关系进行研究。结果表明:(1)不同富士系得到不同的MSAP扩增,总DNA甲基化水平27.90%～36.16%,平均32.87%,双链全甲基化为主要甲基化方式;(2)富士芽变材料绝大多数位点保持了原有甲基化模式;(3)绝大多数芽变(68.57%)检测到全部的甲基化变异模式(12种),去甲基化频率极显著高于甲基化频率(P 0.01),且CG去甲基化极显著高于CHG;(4)36份种质遗传相似系数平均值0.89(0.79～0.92),在聚类图上,富士原种分布在芽变系集中区外,新近发生的芽变系更倾向于聚在一起,着色系片红型和条红型芽变呈分散排布状态。总的来看,富士芽变的甲基化变异模式丰富,超甲基化和去甲基化相伴发生,但以去甲基化为主;‘富士’着色芽变与其最原始品种富士,以及芽变之间发生了较大表观遗传变异;片红和条红型芽变聚类未表现明显偏好性。本研究将为进一步开展富士着色系芽变机理研究提供指导,可以CG去甲基化为切入点展开深入研究。     

Thresholds,sensitive stages and genetic variability of finger millet to high temperature stress

Finger millet [Eleusine coracana (L.) Gaertn.] is an important coarse cereal crop grown in the arid and semi‐arid regions and often experiences high temperature (HT) stress. The objectives of this research were (i) to quantify effects of season‐long HT stress on physiological and yield traits, (ii) to identify the developmental stages most sensitive to HT stress and (iii) to quantify the genetic variability for HT stress tolerance in finger millet. Research was conducted in controlled environment conditions. HT stress decreased the chlorophyll index, photosystem II activity, grain yield and harvest index. Maximum decrease in number of seeds per panicle and grain yield per plant was observed when stress was imposed during booting, panicle emergence or flowering stages. Maximum genotypic variation was explained by panicle width and number of seeds per panicle at optimum temperature (OT) and grain yield per plant at HT and number of seeds at HT. Based on the stress response and grain yield, tolerant or susceptible genotypes were identified. Finger millet is sensitive to HT stress during reproductive stages, and there was genotypic variability among the finger millet genotypes for number of seeds per panicle and grain yield under HT, which can be exploited to enhance stress tolerance.     

一例湖羊纤维素性肺炎的病理组织学观察

为探究四川省某养殖场湖羊患病情况,以1只发病湖羊为例,研究观察病羊临床症状、解剖变化,采用H.E.染色方法分析病羊实质器官病理组织学变化,并从病羊中分离出菌株Z-1,采用生理生化、16S rDNA基因测序对其鉴定,采用腹腔注射对菌株Z-1进行动物回感试验,纸片扩散法对菌株Z-1进行药敏分析。结果表明:患病羊病症有高热、剧烈咳嗽并伴有喘气,口鼻周围可见黄色浓稠分泌物;解剖变化为多个实质器官明显肿大、充血,肺脏充血、颜色暗红,切开有血样泡沫状液体流出;病理组织切片可见肺、肝、脾等组织细胞肿胀、充血、出血,肺泡腔和细支气管中有大量粉红色纤维素性渗出物,炎性细胞浸润;菌株Z-1为革兰氏阳性菌,乳糖、七叶苷和山梨醇等生化反应呈阳性反应,木糖醇、甘露糖和蜜二糖等生化反应呈阴性反应;16S rDNA基因目的片段长度为1 428bp,与菌株NR_026471的相似性达到98%,综合鉴定为链球菌;动物回感试验表明该菌株对小鼠具有很强的致病性;药敏试验表明该菌株对氧氟沙星、诺氟沙星、环丙沙星和庆大霉素等敏感,对氨苄西林、青霉素和拉氧头孢等耐药。综上,该病湖羊患链球菌感染的纤维素性肺炎。     

考虑植株氮垂直分布的夏玉米营养诊断敏感位点筛选

探明夏玉米氮素营养生化指标(叶绿素a、叶绿素b、类胡萝卜素、叶片氮含量和叶片氮积累量)与叶片SPAD值垂直分布特征及两者间定量回归关系,确立基于叶绿素仪的夏玉米氮营养无损诊断敏感叶位和叶片部位,以实现氮营养时空变化的快捷和精准监测。利用2018-2019年连续2季不同氮营养水平下夏玉米关键生育期主茎各叶位(顶1叶~顶12叶,TL1~TL12)和叶片部位(每张叶片从叶片基部开始根据叶片长度每20%分为1个测试区间) SPAD值及氮营养指标数据,研究基于偏最小二乘(partial least square, PLS)回归模型的夏玉米不同位点SPAD值与氮营养指标间关系,确定可稳定指示夏玉米氮营养空间异质性变化的敏感叶位及叶片部位。结果表明,不同叶位间夏玉米叶片SPAD值和氮营养指标于植株间分布均呈典型的"钟型"特征,至TL5或TL6时达至峰值。同一叶位不同部位间SPAD值由20%至100%位点时则逐步升高,且80%~100%位点间无显著差异(P>0.05)。PLS分析结果显示,夏玉米不同叶位SPAD值与氮营养指标间模型精度决定系数(coefficient of determination, R2)和相对分析误差(relative percent deviation,RPD)范围分别为0.693~0.821和1.425~2.744。不同测试位点R2和RPD值范围则分别为0.660~0.847和1.607~2.451,满足模型精确诊断需求。此后,基于PLS模型中各叶位和叶片部位无量纲评价指标变量重要性投影值(variable importance for projection,VIP),确定顶4叶(TL4)完展叶60%~80%区间为夏玉米氮营养诊断的敏感区域,VIP值均高于临界值1.40,预测效果较为理想。研究可为实现氮营养的高效、快捷诊断和精准施氮提供参考。     

定量泵负载敏感系统卸荷压力冲击抑制研究

定量泵负载敏感系统在快速卸荷时容易出现压力冲击现象,对系统的可靠性和寿命产生较大危害。三通压力补偿阀是定量泵负载敏感系统中关键的调压元件,本文以三通压力补偿阀为切入点,建立定量泵负载敏感系统功率键合图模型,基于键合图模型推导系统的状态方程,建立Matlab动态仿真模型,探讨系统卸荷压力冲击的抑制方案。基于系统仿真模型,首先对系统卸荷压力冲击的仿真与试验进行对比,验证了仿真模型的正确性;然后,针对三通压力补偿阀的系统压力腔阻尼、阀芯直径、Ls腔阻尼、阀口锥角等关键参数,对卸荷压力冲击影响规律进行仿真;最后,基于关键参数对卸荷压力冲击影响规律的分析,提出了一种"小阀芯、双阀口"型三通压力补偿阀结构优化方案,并对其卸压冲击抑制效果进行了仿真和试验。结果表明,该方案可以有效抑制卸荷压力冲击,优化后系统卸压冲击压差比原系统降低了89%,卸荷压力降低了20%,进一步实现了节能。     

香果树种子休眠和萌发的生理特性

为了解决香果树Emmenopterys henryi种子萌发困难的问题,使用不同的光照条件较系统地研究了香果树种子休眠和萌发的生理特性.结果表明:香果树种子属典型的光敏感性种子,在黑暗中无论恒温或变温条件下均完全不能萌发;整个萌发过程需1 000 lx光照强度和每天照光16 h;在光照条件下适宜的萌发温度为20℃、25℃恒温,其次是30℃恒温和30℃(日)、20℃(夜)变温.     

土壤盐分离子对浸提液电导率的敏感性分析建模

为了研究土壤盐分离子对浸提液电导率的敏感性,首先采用灰色关联分析法对影响土壤浸提液电导率的盐分离子进行初步分析,之后采用缺省因子法与主成分分析法进一步分析检验.结果表明:Cl-、Na+这两种离子对土壤浸提液电导率的变化最为敏感;灰色关联分析法所得结果与基于缺省因子法的主成分分析模型结果基本一致;影响土壤浸提液电导率的7...     

山西省粮食作物对气候敏感性的分析

利用1961-2008年平均气温、降水量等气象要素资料和冬小麦、玉米等主要农作物的产量资料为依据,分析并探讨了山西省粮食作物对气候的敏感性及其资源利用状况。结果表明：山西省近年来粮食作物产量基本都呈增加趋势,而气候生产力在近48年中下降了301.2kg/hm2,其分布从北到南增加,年际变化和年代际变化都比较明显;年平均...     

母猪热应激敏感指标体系的研究进展

母猪由于其皮下脂肪厚、汗腺不发达等特点,在高温环境下容易发生热应激。有研究表明：热应激会改变其生理状态和血液生化成分等,降低母猪繁殖力,造成严重的经济损失。然而,目前针对母猪热应激敏感指标的研究总体较粗略、评价体系不全面;而且,母猪的耐热性受遗传、年龄和日粮等多种因素的影响,使得准确评价母猪热应激状态比较困难,成为制约母猪适宜环境参数研究的重要因素。笔者在系统总结母猪热应激研究的基础上,从表型、生理、生化、分子等不同层次探讨了相关指标对热应激的敏感程度及其作为母猪热应激评价指标的可行性,以期为生产中母猪热应激诊断及环境参数的优化奠定基础。总结发现：母猪热应激敏感指标有表皮温度、呼吸频率、直肠温度、血液和肝脏热休克蛋白70（HSP70）等;比较敏感的指标有：血中皮质醇（COR）、天门冬氨酸转移酶（AST）、丙氨酸转移酶(ALT)、肌酸激酶（CK）和乳酸脱氢酶（LDH）。其他指标如血清蛋白、血糖、血液免疫细胞、K ⁺、Na ⁺等随母猪热应激也有所变化,可作为辅助参考指标。其中,表皮温度、呼吸频率、直肠温度和HSP70水平可作为评价母猪长期热应激的指标。此外,尽管母猪热应激造成的行为变化相对滞后,但其测定成本低、对动物无应激,仍然具有一定价值。     

Acquired Thermo‐Tolerance and Trans‐Generational Heat Stress Response at Flowering in Rice

In rice, pre‐exposure to sublethal treatment followed by harsh lethal treatment is known to improve tolerance of different abiotic stresses at the vegetative stage within and across generations. Our major aim was to test the phenomenon of thermo‐tolerance at flowering across (trans)‐generations and within generation using rice cultivars contrasting for heat stress tolerance at flowering. To test trans‐generational response, plants were exposed to higher temperature at flowering stage and seeds obtained from previous generations were exposed to heat stress during flowering, which recorded significantly lower fertility when exposed to the same degree of stress in their subsequent generations. A pre‐acclimation to moderately high acclimating temperatures imposed over three different durations during the vegetative and initial reproductive stage showed positive response in the tolerant N22, particularly under severe heat stress (40 °C). This finding indicates the possibility of acquiring ameliorative thermo‐tolerant mechanisms at anthesis, restricted to tolerant genetic backgrounds to combat subsequent harsh conditions within the same generation. However, trans‐generational memory was ineffective in mitigating spikelet sterility losses in both tolerant and susceptible backgrounds. Rice is extremely sensitive to heat stress during flowering; hence, similar exercise across other crops of interest needs to be carried out before generalizing conclusions.