盐胁迫下欧李叶片叶绿体结构及功能与超微弱发光激发的关系

为初步探索叶绿体及其功能与超微弱发光（Ultraweak luminescence,UWL）激发的关系,揭示UWL与植物生长生理的关系及植物中UWL产生的来源,本试验以欧李（Cerasus humilis）为材料,采用室内盆栽试验,设置不同浓度盐胁迫处理,研究盐胁迫下欧李叶片的叶绿体结构和功能（叶绿素代谢、光系统Ⅱ活性、光合性能和能量水平）及UWL的变化规律和相关性。结果表明：（1）盐胁迫降低了欧李叶片的UWL强度,且盐浓度越高,UWL强度下降程度越大;（2）盐胁迫破坏了欧李叶片叶绿体结构,并降低了其功能,具体表现为叶绿素合成主要前体物质（ALA、Mg-ProtoⅨ）含量显著降低,叶绿素降解酶叶绿素酶（Chlase）活性显著升高,导致叶绿素（Chla、Chlb、Car和Chla+b）含量显著降低;同时欧李叶片FV/Fm、FV/FO、PIABS、RC/CSm、φE0和ΨE0快速下降,光系统Ⅱ活性受到严重抑制;进一步Pn、Tr、Gs下降,Ci同时升高,光合性能显著减弱;ATP含量和EC的显著降低,导致能量水平整体下降;（3）欧李叶片UWL强度与其叶绿素代谢物质及叶绿素含量（ALA、Mg-ProtoⅨ、Chla、Chlb、Car和Chla+b）、光系统Ⅱ活性（FV/Fm、FV/FO、PIABS、RC/CSm、φE0、ΨE0）、光合性能（Pn、Tr、Gs）及能量水平（ATP、EC）等参数均呈显著或极显著性正相关关系。（4）盐浓度越高,胁迫时间越长,欧李叶片UWL强度与叶绿体功能各指标变化程度越大,且高浓度处理下的相关性整体高于低浓度处理。可见,在盐胁迫条件下,欧李叶片叶绿体结构被破坏,同时其功能受到损伤活力下降,从而导致UWL强度降低;UWL强度与叶绿体及其功能关系密切,叶绿体可能是UWL的细胞器之一;UWL强度可以用来反映欧李叶片受盐胁迫伤害的程度。     

Nonparametric and semiparametric estimation with sequentially truncated survival data

In observational cohort studies with complex sampling schemes, truncation arises when the time to event of interest is observed only when it falls below or exceeds another random time, that is, the truncation time. In more complex settings, observation may require a particular ordering of event times; we refer to this as sequential truncation. Estimators of the event time distribution have been developed for simple left-truncated or right-truncated data. However, these estimators may be inconsistent under sequential truncation. We propose nonparametric and semiparametric maximum likelihood estimators for the distribution of the event time of interest in the presence of sequential truncation, under two truncation models. We show the equivalence of an inverse probability weighted estimator and a product limit estimator under one of these models. We study the large sample properties of the proposed estimators and derive their asymptotic variance estimators. We evaluate the proposed methods through simulation studies and apply the methods to an Alzheimer's disease study. We have developed an R package, seqTrun , for implementation of our method.     

Effects of ROS and caspase-3-like protein on the growth and aerenchyma formation of Potamogeton perfoliatus stem

Protoplasma - Aerenchyma formation plays an important role in the survival of Potamogeton perfoliatus in submerged environment. To understand the regulatory role of reactive oxygen species (ROS)...     

Effects of compound sodium nitrophenol on microspore embryogenesis and plantlet regeneration in flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee)

Isolated microspore culture has been implemented in breeding programs to produce doubled haploid (DH) lines and thus accelerates the breeding process. However, low microspore embryogenesis frequency in flowering Chinese cabbage remains a key obstacle to the practical application of this technique. This study aimed to establish an efficient microspore culture protocol for flowering Chinese cabbage that would be applied for heterosis breeding. Microspores of five genotypes, 19AY05, 19AY06, 19AY10, 19AY12, and 19AY15, were successfully induced to produce embryos in NLN-13 medium. Microspores of two genotypes, 19AY05 and 19AY15, were cultivated in NLN-13 medium supplemented with different concentrations (0, 0.01, 0.05, 0.1, or 0.2 mg·L⁻¹) of compound sodium nitrophenol (sodium nitrophenol, 5-nitrophenol) to enhance microspore embryogenesis and plant regeneration without an intervening callus phase. The results showed that 0.05 ~ 0.1 mg· L⁻¹ sodium nitrophenol and 0.01 ~ 0.2 mg· L⁻¹ of 5-nitrophenol significantly promoted the induction of microspore embryogenesis of two genotypes, and the best concentrations required for different genotypes are different. Moreover, 0.1 mg· L⁻¹ sodium nitrophenol can significantly increase the plant regeneration rate of the two genetypes. The 5-nitrophenol at 0.01 mg·L⁻¹ significantly increased rate of embryos directly convert to plant in 19AY15. In addition, the average doubled haploid rates in the five genotypes were close to 63%. Horticultural traits of DH lines from 19AY05 were identified and all of them were self-incompatible lines. They showed a high uniformity and consistency that can be directly used for hybrid breeding. Furthermore, the hybrid combination was prepared with the selected DH lines and the Guangdong nucleus genic sterile line GMS019 to screen the excellent hybrid combination for the flowering Chinese cabbage breeding program. This method accelerates the application of microspore culture in hybrid breeding of flowering Chinese cabbage.

     

Investigation of <i>GhFAT</i> Genes Related to Seed Oil Content and Fatty Acid Composition in <i>Gossypium hirsutum</i> L.

Fatty Acyl-ACP thioesterase (FAT) is a key enzyme controlling oil biosynthesis in plant seeds. FATs can be divided into two subfamilies, FATA and FATB according to their amino acid sequences and substrate specificity. The Upland cotton genome contains 20 GhFAT genes, amongst which 6 genes were of the GhFATA subfamily and 14 of the GhFATB subfamily. The 20 GhFAT genes are unevenly distributed on 14 chromosomes. The GhFATA genes have 5 or 7 exons and the GhFATB genes have 6 or 7 exons. All GhFAT proteins have the conserved Acyl-ACP_TE domain and PLN02370 super family, the typical characteristics of plant thioesterases. Analyses of the expression level of GhFATs and the compositions of fatty acid in 5–60 days-post-anthesis seeds showed that the ratio of saturated fatty acids to unsaturated fatty acids was consistent with the expression profile of GhFATB12, GhFATB3, and GhFATB10; the ratio of monounsaturated fatty acid to polyunsaturated fatty acids was consistent with the expression profile of GhFATA3. The oil contents of mature cottonseeds were positively correlated with the contents of palmitic acid and linolenic acid as well as seed vigor. These results provide essential information for further exploring the role(s) of the specific GhFATs in determining oil biosynthesis and cottonseed compositions.     

废用条件下大鼠和达乌尔黄鼠骨骼肌氧化应激和抗氧化防御能力与肌萎缩的比较研究

有鳞类(蛇和蜥蜴)具有较发达的嗅器和犁鼻器,对其不同种类嗅觉结构的认识有助于阐明爬行动物化学感觉的进化。本文采用组织学方法比较了草原沙蜥(Phrynocephalus frontalis)、荒漠沙蜥(P. przewalskii)、密点麻蜥(Eremias multiocellata)和秦岭滑蜥(Scincella tsinlingensis)的嗅器及犁鼻器。结果发现,草原沙蜥的鼻腔较为狭长,秦岭滑蜥呈梨形,其他两种蜥蜴的鼻腔略成圆形。秦岭滑蜥的嗅上皮最厚,其次是密点麻蜥和草原沙蜥,荒漠沙蜥最薄。犁鼻器主要由犁鼻腔、犁鼻感觉上皮、犁鼻神经及蘑菇体等组成,没有腺体。草原沙蜥和荒漠沙蜥的犁鼻腔较为宽阔,密点麻蜥和秦岭滑蜥的较窄。4种蜥蜴的犁鼻感觉上皮均较嗅上皮厚,蘑菇体向后逐渐缩小至消失,犁鼻感觉上皮成闭环状,包围犁鼻腔。密点麻蜥和秦岭滑蜥的犁鼻感觉上皮位于犁鼻器的背侧,蘑菇体位于腹侧;与此不同,两种沙蜥的犁鼻感觉上皮偏向于犁鼻器的腹内侧,蘑菇体位于背外侧。密点麻蜥的犁鼻感觉上皮最厚,其次为秦岭滑蜥,两种沙蜥最薄;秦岭滑蜥犁鼻感觉上皮的感觉细胞密度最高,其次是密点麻蜥,两种沙蜥最低。这些结果提示,密点麻蜥和秦岭滑蜥对嗅觉信号的依赖和投入较两种沙蜥多;4种蜥蜴犁鼻器的结构差异间接地佐证了有鳞类犁鼻器系统发生的特异性。     

灵芝液态发酵胞内外多糖结构特征及其活性研究进展

灵芝是一味传统的中药材,具有很高的药用价值,多糖是其主要的活性成分之一,可从其子实体、孢子粉、发酵菌丝体和胞外液中获得。近年来,从灵芝菌丝体和胞外液中发现的多糖越来越得到研究者们的关注。本文从发酵培养基成分及发酵条件对灵芝胞内外多糖的影响、灵芝胞内外多糖的结构、灵芝胞内外多糖生物活性3个方面进行综述,为发酵来源灵芝多糖的开发利用提供科学理论依据。     

水产动物副溶血弧菌病及其噬菌体防治研究进展

副溶血弧菌是水产动物弧菌病的重要病原微生物之一,又是食源性致病菌,摄入被其污染的水产品后可引发肠胃炎、败血症和坏死性筋膜炎等疾病,对水产养殖业及公共卫生安全均具有较大威胁。抗生素大量使用甚至滥用,不可避免地会带来水产品药物残留和细菌耐药等问题,开发安全有效的抗生素替代品迫在眉睫。作为细菌病毒,噬菌体具有宿主特异性强、易筛选、易保存、高效直接等优点,在水产养殖病害防控和食品安全领域受到广泛关注。本文概述了水产动物的副溶血弧菌病及该菌噬菌体防治的研究进展,为副溶血弧菌噬菌体及制剂应用于水产养殖病害生物防控提供参考。     

新疆阿克苏地区一株羊源沙门菌及其小菌落变异株的生物学特性

【背景】小菌落变异株(smallcolonyvariant,SCV)是一种具有独特的表型及致病特征且生长缓慢的细菌亚群,而国内鲜有关于食源性沙门菌SCV的研究报道。【目的】为食源性沙门菌的防治及动物性食品安全提供实验数据。【方法】使用氨基糖苷类抗生素对羊源胆汁中分离的沙门菌进行实验室诱导得到SCV,然后分别对野生株和诱导株的菌落形态、生长、生化特性、营养缺陷型检测、运动性、耐药性检测及耐药基因、毒力基因、生物被膜形成能力进行比较和分析。【结果】经卡那霉素诱导获得一株血红素依赖型沙门菌SCV,与野生株相比,诱导株生长缓慢,低于野生株84%,不利用柠檬酸盐,溶血能力增强40%,对磺胺类和氨基糖苷类药物的耐受性增强,生物被膜形成能力减弱45%,运动能力减弱78%。【结论】沙门菌SCV的生长和生理生化特性与野生株相比有显著差异,使得沙门菌SCV的分离鉴定尤为困难;并且SCV的致病性与耐药性等方面的变化可能给沙门菌病的防治带来更大挑战,其机制还有待深入研究。