信号分子ppGpp与微生物环境适应性

微生物能感知环境胁迫信号,通过触发严谨反应对生长速率进行调节,并通过一系列代谢调控,使细胞能在不利环境中生存。高度磷酸化的鸟苷四/五磷酸ppGpp/pppGpp（文中以ppGpp统称）作为信号分子对微生物生理具有广泛的调节作用,至今仍是微生物学研究热点之一。ppGpp对于微生物适应高温、高压等环境起到了积极的作用。综述了信号分子ppGpp合成降解机制及其调控微生物适应性方面的研究进展。     

Evolutionary ecology of opsin gene sequence,expression and repertoire

Linking molecular evolution to biological function is a long‐standing challenge in evolutionary biology. Some of the best examples of this involve opsins, the genes that encode the molecular basis of light reception. In this issue of Molecular Ecology, three studies examine opsin gene sequence, expression and repertoire to determine how natural selection has shaped the visual system. First, Escobar‐Camacho et al. ( 2017 ) use opsin repertoire and expression in three Amazonian cichlid species to show that a shift in sensitivity towards longer wavelengths is coincident with the long‐wavelength‐dominated Amazon basin. Second, Stieb et al. ( 2017 ) explore opsin sequence and expression in reef‐dwelling damselfish and find that UV‐ and long‐wavelength vision are both important, but likely for different ecological functions. Lastly, Suvorov et al. ( 2017 ) study an expansive opsin repertoire in the insect order Odonata and find evidence that copy number expansion is consistent with the permanent heterozygote model of gene duplication. Together these studies emphasize the utility of opsin genes for studying both the local adaptation of sensory systems and, more generally, gene family evolution.     

Detection and validation of EST‐derived SNPs for poplar leaf rust Melampsora medusae f. sp. deltoidae

We report the discovery, characterization and validation of 118 single nucleotide polymorphisms (SNPs) for poplar leaf rust Melampsora medusae f. sp. deltoidae identified using a gene‐targeted approach in an expressed sequence tag (EST) library. We developed a genotyping assay using the iPLEX? primer extension method for two multiplex assays of 28 and 22 SNPs.     

Multiple chromosomal rearrangements in a hybrid zone between Littorina saxatilis ecotypes

Both classical and recent studies suggest that chromosomal inversion polymorphisms are important in adaptation and speciation. However, biases in discovery and reporting of inversions make it difficult to assess their prevalence and biological importance. Here, we use an approach based on linkage disequilibrium among markers genotyped for samples collected across a transect between contrasting habitats to detect chromosomal rearrangements de novo. We report 17 polymorphic rearrangements in a single locality for the coastal marine snail, Littorina saxatilis. Patterns of diversity in the field and of recombination in controlled crosses provide strong evidence that at least the majority of these rearrangements are inversions. Most show clinal changes in frequency between habitats, suggestive of divergent selection, but only one appears to be fixed for different arrangements in the two habitats. Consistent with widespread evidence for balancing selection on inversion polymorphisms, we argue that a combination of heterosis and divergent selection can explain the observed patterns and should be considered in other systems spanning environmental gradients.     

Diversity of halophilic microorganisms: Environments,phylogeny, physiology,and applications

The phylogenetic diversity of microorganisms living at high salt concentrations is surprising. Halophiles are found in each of the three domains: Archaea, Bacteria, and Eucarya. The metabolic diversity of halophiles is great as well: they include oxygenic and anoxygenic phototrophs, aerobic heterotrophs, fermenters, denitrifiers, sulfate reducers, and methanogens. The diversity of metabolic types encountered decreases with salinity. The upper salinity limit at which each dissimilatory process takes place is correlated with the amount of energy generated and the energetic cost of osmotic adaptation. Our understanding of the biodiversity in salt-saturated environments has increased greatly in recent years. Using a combination of culture techniques, molecular biological methods, and chemotaxonomic studies, we have obtained information on the nature of the halophilic Archaea as well as the halophilic Bacteria that inhabit saltern crystallizer ponds. Several halophilic microorganisms are being exploited in biotechnology. In some cases, such as the production of ectoine, the product is directly related to the halophilic behavior of the producing microorganism. In other cases, such as the extraction of β-carotene from Dunaliella or the potential use of Haloferax species for the production of poly-β-hydroxyalkanoate or extracellular polysaccharides, similar products can be obtained from non-halophiles, but halophilic microorganisms may present advantages over the use of non-halophilic counterparts. Journal of Industrial Microbiology & Biotechnology (2002) 28, 56–63 DOI: 10.1038/sj/jim/7000176 Received 20 May 2001/ Accepted in revised form 20 June 2001     

昆虫记忆的形成机制及生态适应性

介绍近十几年来利用蜜蜂Apis mellifera L.、果蝇Drosophila melanogaster Meigen和寄生蜂等昆虫对学习和记忆行为研究的成果。这些研究表明昆虫的记忆形成是多阶段的。从短时记忆向长时记忆的形成过程中,cAMP反应元件结合蛋白(cAMP response element-bindingprotein,CREB)起重要的作用;而蘑菇体是学习、记忆形成的主要位点。已有的研究还表明昆虫记忆的动态是适应于不同物种的生态学需要。这些研究为探索昆虫和其它动物记忆的形成和生态适应性提供了理论基础。     

喀斯特石漠结皮细尖鳞叶藓的吸水机制及耐旱适应性

生物结皮是由隐花植物和相关土壤微小生物与表层土壤颗粒胶结而形成的复合体,与维管束植物覆盖一样,它是干旱区地表的重要覆盖类型。苔藓是荒漠植被演替过程中常见的一类先锋植物,同时也是生物结皮中生物量最大的2个类群之一。研究了结皮细尖鳞叶藓的吸水机制和耐旱适应性。结果表明:细尖鳞叶藓最大吸水量和持水率分别达到干重的9.74倍和700%以上,动力学总吸水过程的表观Km值和Vmax值分别为21.67g、10.42g·g-·1DW·min-1,外吸水过程为28.91g和8.56g·g-·1DW·min-1,内吸水过程为43.18g和1.76g·g-·1DW·min-1。可溶性糖含量从142.6mg·g-·1DW(CK)上升到344.3mg·g-·1DW,增长近2.4倍,而游离脯氨酸积累微弱。抗氧化酶SOD活性变化不明显,在0.04U·g-·1FW上下浮动;POD活性在PEG6000胁迫浓度在20%之前呈大幅度上升状态,以后趋于缓和,30%时达最高的131U·g-·1min-·1FW,增加近2倍;CAT活性的变化情况与POD变化趋势相同,但变化量较小。膜脂过氧化指标MDA先略有升高又逐步回落,说明细尖鳞叶藓抗氧化酶系统利用提高POD和CAT活性清除SOD在清除超氧阴离子自由基过程中产生的H2O2。因此,在喀斯特石漠化缺少土壤、极度干旱且保水能力弱的环境区域,结皮藓类植物以其特有的吸水特征、持水功能和抗旱机制等生态功能在石漠化治理、退化生态系统的恢复中具有十分重要的作用。     

绿原酸提高舞毒蛾核型多角体病毒(LdNPV)的致病力

【目的】明确绿原酸(chlorogenic acid,CA)对舞毒蛾核型多角体病毒Lymantria dispar necleopolyhydrovirus(Ld NPV)致病力的影响,为舞毒蛾的防治提供参考依据。【方法】采用食料给毒法进行生物测定,测定舞毒蛾2龄幼虫对单独Ld NPV及添加绿原酸的Ld NPV(CA+Ld NPV)的剂量及致死时间响应。【结果】CA+Ld NPV与单独Ld NPV对舞毒蛾2龄幼虫的剂量及时间响应间有显著差异,二者对舞毒蛾2龄幼虫的致死中浓度(LC50)分别为161.8 OBs/μL(95%的置信区间为105.6~235.3 OBs/μL)和264.4 OBs/μL(95%的置信区间为178.6~384.0 OBs/μL),前者对舞毒蛾的致病力较后者强。CA+Ld NPV对舞毒蛾2龄幼虫的致死中时间(LT_(50))较Ld NPV的短,当Ld NPV浓度为590 OBs/μL,CA+Ld NPV及Ld NPV对舞毒蛾2龄幼虫的LT_(50)分别为9.9 d和12.3 d;当Ld NPV浓度为5 900 OBs/μL时,则LT_(50)分别为6.9 d和8.0 d。绿原酸降低了Ld NPV对舞毒蛾幼虫的致死中浓度,缩短了致死中时间。【结论】绿原酸可提高Ld NPV对舞毒蛾2龄幼虫的致病力,其机理有待进一步研究。     

细胞培养技术在植物抗性生理研究领域中的应用

本文综述了近10年来有关利用细胞培养技术所进行的抗性生理领域的研究成果,包括在培养过程中植物细胞对外界胁迫的反应、有关利用细胞培养技术研究植物的抗逆性反应,以及植物抗逆性的理论在实际中的应用。大量的实验证明,细胞培养技术在植物抗逆性研究领域具有广阔的应用前景。