Nucleoid Visible vs. Non-Nucleoid Visible Bacterial Cells: A New Approach to Assessing in Situ Bacterioplankton Dynamics

9633712 Sherr 异养细菌处理大部分的初级 在海洋中生产，并负责一个重大的 海洋食品中的呼吸和矿化部分 网。因此，阐明细菌的作用对于 了解海洋的结构和功能 特别是在海洋生态系统的作用方面 生物群在吸收大气中的二氧化碳。一个新 荧光，DNA染色法显示， 浮游细菌可分为两组细胞： 那些有，和那些没有，可见nucleoids（作为 通过该方法可视化）。初步工作表明， 具有可见类核的细胞（NV细胞）代表 浮游细菌群落的组成部分，包括 目前代谢活跃和最近活跃 细胞没有可见的类核细胞（非NV）似乎是 不活跃/休眠;但在适当的条件下， 细胞可以产生可见的类核，因此非NV细胞必须 含有DNA在沿海浮游细菌群落中， NV细胞比例（20 ~ 60%）和细胞比例（20 ~ 60%） 被鉴定为代谢活性（6% -40%， 总细菌丰度的变量。的能力 标识当前活动+最近活动的部分 细菌浮游生物在常规基础上可能提供令人兴奋的新 组件可以整合细菌的反应， 在较长的时间尺度上对环境变化的影响 （天-周）比目前活跃的部分， 集合（小时-天的时间尺度）。此外该 目前活跃的：NV细胞的比例是一个潜在的有价值的 NV细菌生长状态的指标。这个项目 代表了实验室和现场取样相结合的程序 评估NV与非NV细胞在 浮游细菌群落需要审查的想法包括： 1)非NV细胞可以通过增加 DNA/细胞的数量。2)NV细胞受到更大的 放牧死亡率相比，非NV细胞，这可能 部分解释了非活性细胞的持续存在， 浮游细菌3)浮游细菌的NV组分 集合与自下而上的指数耦合更紧密 对照（叶绿素-a浓度，细菌 生产力）和自上而下的控制（丰富的 nanoflagellates，率bacterivory）比总的 沿海上升流系统中的细菌丰度。的 该研究项目的结果将产生重要的新成果。 关于海洋浮游细菌如何应对 控制它们在海洋中生长和生物量的因素。 ***

9633712 SHERR Heterotrophic bacteria process a large share of primary production in the sea, and are responsible for a significant portion of respiration and remineralization in marine food webs. Elucidating the roles of bacteria is thus essential to understanding the structure and functioning of marine ecosystems, particularly with respect to the role of marine biota in sequestering atmospheric carbon dioxide. A new epifluorescence, DNA staining method has revealed that bacterioplankton can be divided into two groups of cells: those with, and those without, visible nucleoids (as visualized by the method). Preliminary work suggests that cells with visible nucleoids (NV cells) represent the component of the bacterioplankton assemblage that includes both currently metabolically active and recently active cells. Cells without visible nucleoids (non-NV) appear to be inactive/dormant; however under appropriate conditions such cells can develop visible nucleoids, thus non-NV cells must contain DNA. In coastal bacterioplankton assemblages,the fraction of NV cells (20 ~ - 60%), and of cells separately identified as metabolically active (6% - 40%, was more variable than total bacterial abundance. The ability to identify the currently active + recently active portion of bacterioplankton on a routine basis may provide exciting new component can integrate the response of a bacterial assemblage to environmental change over longer time scales (days-weeks) than would the currently active fraction of the assemblage (time scale of hours-days). In addition, the ratio of currently active:NV cells is a potentially valuable index of the growth state of NV bacteria. This project represents a combined laboratory and field sampling program to evaluate the implications of NV versus non-NV cells in bacterioplankton assemblages. Ideas to be examined include: 1) Non-NV cells can develop visible nucleoids by increasing the amount of DNA/cell. 2) NV cells are subject to greater grazing mortality compared to non-NV cells, which could explain in part the persistence of inactive cells in bacterioplankton. 3) The NV component of bacterioplankton assemblages is more tightly coupled to indices of bottom-up control (chlorophyll-a concentration, bacterial productivity), and of top-down control (abundance of nanoflagellates, rate of bacterivory) than is total bacterial abundance in a coastal upwelling system. The results of this research project should yield important new insights concerning how marine bacterioplankton respond to factors controlling their growth and biomass in the sea. ***