光周期对青饲玉米耐高氮的调控效应

以光周期敏感型‘华农1号’青饲玉米为材料,在大田条件下,设置N1(75kg/hm2)、N2(225kg/hm2)、N3(375kg/hm2)3个氮素水平和3个光周期处理(16h、13h和10h),分析了其在不同光照长度条件下耐高氮胁迫的能力,探讨光周期对玉米氮高效相关的农艺性状和光合特性指标的影响。结果表明,(1)16h光照处理下,玉米植株的根长、根表面积、根体积分别比10h处理增加了113.19%、45.73%和97.71%,叶片叶绿素含量与净光合速率比10h处理分别提高97.90%和60.24%,且根长、根体积、叶绿素含量和净光合速率在16h和10h处理下差异极显著;16h处理与10h处理叶片数的平均相差值(12)显著,根系直径随光周期延长逐渐减小,但光周期对植株分蘖数无显著影响。(2)‘华农1号’青饲玉米地下部和地上部部分农艺性状指标,在16h长光照处理下随氮素水平的提高而增加,表现出耐高氮胁迫的生物学特征;在10h短光照处理下氮素水平过高相关性状指标反而下降。(3)随着光照时间逐渐延长,地上部生物量逐渐显著增加。研究发现,光周期敏感型‘华农1号’青饲玉米具有较强的耐高氮能力,长光周期促进了其植株营养生长阶段的生长发育,增强了其对高氮的适应能力。     

Length-weight relationships of Ponto-Caspian gammarids that have overcome the salinity barrier of the southern Baltic Sea coastal waters

Gammarids from the Caspian complex have invaded many European waters along the rivers and canals of the inland migration corridors. The species examined in this work are well known as invaders of European freshwater environments, so the colonization of brackish habitats is a phenomenon inviting more detailed investigation. The aim of this study was to determine the condition of the Ponto-Caspian gammarids Pontogammarus robustoides (G.O. Sars, 1894), Obesogammarus crassus (G.O. Sars, 1894), Dikerogammarus haemobaphes (Eichwald, 1841) and Dikerogammarus villosus (Sowinsky, 1894) as expressed by the relationship between total length and the wet weight of specimens in the brackish waters of the Gulf of Gdansk (Poland). The relationships can be regarded as responses to a newly expanded habitat after they overcome the salinity barrier of the southern Baltic Sea coastal waters. All these Ponto-Caspian gammarids demonstrated an increase in weight with increasing total length: P. robustoides (b = 2.852), O. crassus (b = 3.3477), D. haemobaphes (b = 3.7855) and D. villosus (b = 2.6917). The results are an indicator of the relatively good condition of the organisms and indicate that the brackish environment of the Gulf of Gdansk affords them excellent possibilities for growth.     

The diet of whiting Merlangius merlangus in the western Baltic Sea

The diet of whiting Merlangius merlangus in the western Baltic Sea was investigated and compared to the diet in the southern North Sea. Clupeids were important prey in both areas, but especially in the western Baltic Sea where they constituted up to 90% of the diet of larger individuals. Gobies, brown shrimps and polychaetes were the main prey of juveniles in the western Baltic Sea, while a wider range of species were consumed in the North Sea. The shift to piscivory occurred at smaller sizes in the western Baltic Sea and the fish prey consumed was proportionately larger than in the southern North Sea. Estimates of prey abundance and food intake of M. merlangus are required to evaluate its predatory significance in the western Baltic Sea, but its diet suggests that it could be just as significant a fish predator here as in the southern North Sea.     

The phytoplasma associated with purple woodnettle witches'‐broom disease in Taiwan represents a new subgroup of the aster yellows phytoplasma group

In October 2013, a new disease affecting purple woodnettle, Oreocnide pedunculata, plants was found in Miaoli County, Taiwan. Diseased plants exhibited leaf yellowing and witches'‐broom symptoms. Molecular diagnostic tools and electron microscopic cell observation were used to investigate the possible cause of the disease with a specific focus on phytoplasmas. The result of polymerase chain reaction with universal primer pairs indicated that phytoplasmas were strongly associated with the symptomatic purple woodnettles. The virtual restriction fragment length polymorphism (RFLP) patterns and phylogenetic analysis based on 16S rDNA and ribosomal protein, rplV‐rpsC region revealed that purple woodnettle witches'‐broom phytoplasma (PWWB) belongs to a new subgroup of 16SrI and rpI group and was designated as 16SrI‐AH and rpI‐Q, respectively, herein. RFLP analysis based on tuf gene region revealed that the PWWB belongs to tufI‐B, but phylogenetic analysis suggested that PWWB should be delineated to a new subgroup under the tufI group. Taken together, our analyses based on 16S rRNA and rplV‐rpsC region gave a finer differentiation while classifying the subgroup of aster yellows group phytoplasmas. To our knowledge, this is the first report of a Candidatus Phytoplasma asteris‐related strain in 16SrI‐AH, rpI‐Q and tufI‐B subgroup affecting purple woodnettle, and of an official documentation of purple woodnettle as being a new host of phytoplasmas.     

Interaction parameters between carbon nanotubes and water in Dissipative Particle Dynamics

Flow of water past an array of single-walled carbon nanotubes (SWNTs) is simulated in this work to determine the interaction parameters of carbon nanotubes (CNTs) and water using Dissipative Particle Dynamics (DPD). For this flow configuration, results from molecular dynamics simulations by Walther et al. are available and can be used for validation (Phys. Rev. E, 2004, 062201). The hydrodynamic properties for SWNT (32, 0) with diameter of 2.5 nm were determined in different Reynolds number flows. A set of appropriate DPD parameters was found so that the drag coefficients of the CNT agreed well with the Stokes–Oseen analytical solution and the fluid slip length on the CNT wall was comparable with the Walther et al. results. It was also found that it is feasible to apply these parameters in longer length and time scales by increasing the number of water molecules grouped into each DPD bead and still maintain the hydrodynamic properties of CNTs as well as their hydrophobic surface character.     

克拉玛依油田石油污染土壤细菌群落结构与环境因子的关系

【目的】以16S rRNA为分子标记,探讨克拉玛依油田石油污染土壤中细菌群落多样性和系统发育,并分析环境因子对群落分布的影响,为生物降解石油污染物提供理论基础。【方法】在克拉玛依油田分别采集深度为5、20、50 cm的石油污染土壤样品,测定环境参数;提取石油污染土壤细菌群落基因组DNA,分别构建3个土层细菌16S rRNA基因文库,利用限制性片段长度多态性分析(Restriction fragment length polymorphisms RFLP)技术初步分群,确定各文库中的代表菌株并测定16S rRNA基因序列;利用软件Biodap计算各群落多样性和丰富度指数,以Neighbor-Joining法构建3个土层细菌的系统发育树;运用软件CANOCO 4.5结合不同样品环境因子的差异进行典型对应分析(CCA),并探讨了环境因子对细菌多样性的影响。【结果】环境参数结果表明20 cm土层总磷(TP)、总氮(TN)含量最低,50 cm含量最高;5 cm土层中有机碳(TOC)含量最高,50 cm含量最低。基于16S rRNA序列的生物多样性和物种丰富度指数表明20 cm土层生物多样性和丰富度指数较高,而50 cm土层各项指数均较低。各土层供试序列RFLP聚类分析表明,克拉玛依油田石油污染土壤细菌种群具有丰富的多样性。Neighbor-Joining构建的系统发育分析表明,石油污染土壤被分为5个类群(I–V),分别为变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、厚壁菌门(Firmicute)、拟杆菌门(Bacteroidetes)、浮霉状菌门(Planctomycetes),其中群Ⅰ占78.57%,广泛分布于不同的生态环境;其中来自5 cm土层代表菌的69.23%分布于群Ⅰ。CCA分析结果显示TN、TP和TOC对大部分细菌影响较大;TOC含量对Pseudomonas影响明显。【结论】克拉玛依油田石油污染土壤细菌群落具有丰富的多样性;环境因子是影响石油污染土壤细菌群落空间分布的重要因素。     

Lifelong leukocyte telomere dynamics and survival in a free‐living mammal

Telomeres play a fundamental role in the maintenance of genomic integrity at a cellular level, and average leukocyte telomere length (LTL) has been proposed as a biomarker of organismal aging. However, studies tracking LTL across the entire life course of individuals are lacking. Here, we examined lifelong patterns of variation in LTL among four birth cohorts of female Soay sheep (Ovis aries) that were longitudinally monitored and sampled from birth to death. Over the first 4 months of life, there was within‐individual loss of LTL, consistent with findings in the human and primate literature, but there was little evidence of consistent LTL loss associated with age after this point. Overall, we observed only weak evidence of individual consistency in LTL across years and over the entire lifespan: Within‐individual variation was considerable, and birth cohorts differed markedly in their telomere dynamics. Despite the high levels of LTL variation within the lifetimes of individuals, there remained significant associations between LTL and longevity. Detailed analysis of the longitudinal data set showed that this association was driven by improved survival of individuals with longer LTL over the first 2 years of life. There was no evidence that LTL predicted survival in later adulthood. Our data provide the first evidence from a mammal that LTL can predict mortality and lifespan under natural conditions, and also highlight the potentially dynamic nature of LTL within the lifetimes of individuals experiencing a complex and highly variable environment.