Misson Benjamin, Sabart Marion, Amblard Christian, Latour Delphine
Laboratoire "Microorganismes: Génome et Environnement", UMR CNRS 6023, Université Blaise Pascal, Clermont-Ferrand II, 63171 Aubière Cedex, France.
J Phycol. 2011 Feb;47(1):42-51. doi: 10.1111/j.1529-8817.2010.00943.x. Epub 2011 Jan 13.
The benthic recruitment of Microcystis was simulated in vitro in order to characterize the colonies of Microcystis recruited and to study the impact of intracellular and extracellular microcystins (MCs), and the influence of colony size on the recruitment process. We observed recruitment dynamics consisting of a lag phase followed by a peak and then a return to low recruitment rates, mainly controlled by passive resuspension throughout the experiment, and by physiological processes during the recruitment peak. Ninety-seven percent of the Microcystis colonies recruited were <160 μm in maximum length, and their cells contained much greater amounts of MCs (0.26 ± 0.14 pg eq microcystin leucine-arginine variant [MC-LR] · cell(-1) ) than those in benthic colonies (0.021 ± 0.004 pg eq MC-LR · cell(-1) ). The MC content of recruited Microcystis varied significantly over time and was not related to changes in the proportion of potentially toxic genotypes, determined using real-time PCR. On the other hand, the changes in MC content in the potentially toxic Microcystis recruited were closely and negatively correlated with recruitment dynamics; the lowest MC contents corresponded to high recruitment rates, and the highest MC contents corresponded to low recruitment rates. Thus, depending on temperature and light conditions, these variations are thought to result from the selection of various subpopulations from among the smallest and the most toxic of the initial benthic population. Adding purified MC-LR to experimental treatments led to a decreased recruitment of Microcystis and more specifically of mcyB genotypes.
为了表征招募的微囊藻群体特征，研究细胞内和细胞外微囊藻毒素（MCs）的影响以及群体大小对招募过程的影响，在体外模拟了微囊藻的底栖招募。我们观察到招募动态包括一个滞后期，随后是一个峰值，然后招募率恢复到低水平，在整个实验过程中主要受被动再悬浮控制，在招募峰值期间受生理过程控制。招募的微囊藻群体中97%的最大长度小于160μm，其细胞中的MCs含量（0.26±0.14 pg 当量微囊藻毒素亮氨酸-精氨酸变体[MC-LR]·细胞⁻¹）比底栖群体中的细胞（0.021±0.004 pg 当量MC-LR·细胞⁻¹）多得多。招募的微囊藻的MC含量随时间有显著变化，且与使用实时PCR测定的潜在毒性基因型比例的变化无关。另一方面，招募的潜在毒性微囊藻中MC含量的变化与招募动态密切负相关；最低的MC含量对应高招募率，最高的MC含量对应低招募率。因此，根据温度和光照条件，这些变化被认为是由于从初始底栖群体中最小且毒性最大的各种亚群中进行选择的结果。在实验处理中添加纯化的MC-LR导致微囊藻的招募减少，更具体地说是mcyB基因型的招募减少。
