Bouvier Thierry, Del Giorgio Paul A, Gasol Josep M
Laboratoire Ecosystèmes Lagunaires, UMR5119 CNRS-UM2, Université Montpellier 2, case 093, 34095 Montpellier cedex 05, France.
Environ Microbiol. 2007 Aug;9(8):2050-66. doi: 10.1111/j.1462-2920.2007.01321.x.
Flow cytometry has revealed the existence of two distinct fractions of bacterioplankton cells, characterized by high and low nucleic acid contents (HNA and LNA cells). Although these fractions seem ubiquitous in aquatic systems, little is known concerning the variation in the cytometric parameters used to characterize them. We have performed cytometric analyses of samples from a wide range of aquatic systems to determine the magnitude and variability in the cytometric characteristics of HNA/LNA. We show that neither group is associated to a fixed level of fluorescence and of light scatter. Rather, the relative position of HNA and LNA in the fluorescence versus side scatter cytograms varies greatly, both within and among ecosystems. Although the cytometric parameters of both groups tend to covary, there is often uncoupling between the two, particularly in light scatter. Our results show that, although the basic HNA/LNA configuration is present in most samples, its cytometric expression changes greatly in different ecosystems and along productivity gradients. The patterns in cytometric parameters do not support the simple, dichotomous view of HNA and LNA as active and inactive cells, or the notion of two distinct and independent communities, but rather suggest that there may be cells that are intrinsic to each fraction, as well as others that may exchange between fractions.
流式细胞术已揭示存在两类不同的浮游细菌细胞，其特征在于核酸含量高和低（高核酸含量细胞和低核酸含量细胞）。尽管这些细胞组分在水生系统中似乎普遍存在，但对于用于表征它们的细胞计量学参数的变化却知之甚少。我们对来自广泛水生系统的样本进行了细胞计量学分析，以确定高核酸含量/低核酸含量细胞的细胞计量学特征的大小和变异性。我们表明，这两类细胞均与固定水平的荧光和光散射无关。相反，在荧光与侧向散射细胞图中，高核酸含量细胞和低核酸含量细胞的相对位置在生态系统内部和之间都有很大变化。尽管两类细胞的细胞计量学参数往往相互协变，但两者之间经常出现解耦，特别是在光散射方面。我们的结果表明，尽管大多数样本中都存在基本的高核酸含量/低核酸含量细胞结构，但其细胞计量学表达在不同生态系统和沿生产力梯度上变化很大。细胞计量学参数模式不支持将高核酸含量细胞和低核酸含量细胞简单地二分法视为活跃和不活跃细胞，或两个不同且独立群落的概念，而是表明可能存在属于每个细胞组分固有的细胞，以及其他可能在细胞组分之间交换的细胞。
