Université de Toulouse, INP, UPS, Ecolab (Laboratoire d'Ecologie Fonctionnelle et Environnement), Toulouse, France ; Centre National de la Recherche Scientifique, Ecolab, Toulouse, France ; Université de la Rochelle, CNRS, UMR 7266 LIENSs (Littoral Environnement et Sociétés), La Rochelle, France.
PLoS One. 2013 Sep 20;8(9):e75352. doi: 10.1371/journal.pone.0075352. eCollection 2013.
In situ pigment contents of biofilm-dwelling bdelloid rotifers of the Garonne River (France) were measured by high performance liquid chromatography (HPLC) and compared with pigment composition of surrounding biofilm microphytobenthic communities. Among pigments that were detected in rotifers, the presence of carotenoids fucoxanthin and myxoxanthophyll showed that the rotifers fed on diatoms and cyanobacteria. Unexpectedly, while diatoms strongly dominated microphytobenthic communities in terms of biomass, HPLC results hinted that rotifers selectively ingested benthic filamentous cyanobacteria. In doing so, rotifers could daily remove a substantial fraction (up to 28%) of this cyanobacterial biomass. The possibility that the rotifers hosted symbiotic myxoxanthophyll-containing cyanobacteria was examined by localisation of chlorophyll fluorescence within rotifers using confocal laser scanning microscopy (CLSM). CLSM results showed an even distribution of quasi-circular fluorescent objects (FO) throughout rotifer bodies, whereas myxoxanthophyll is a biomarker pigment of filamentous cyanobacteria, so the hypothesis was rejected. Our results also suggest that rotifers converted β-carotene (provided by ingested algae) into echinenone, a photoprotective pigment. This study, which is the first one to detail in situ pigment contents of rotifers, clearly shows that the role of cyanobacteria as a food source for meiobenthic invertebrates has been underestimated so far, and deserves urgent consideration.
通过高效液相色谱法（HPLC）测量了加龙河（法国）生物膜栖居的蛭形轮虫的原位色素含量，并将其与周围生物膜微型底栖植物群落的色素组成进行了比较。在轮虫中检测到的色素中，类胡萝卜素岩藻黄素和甲藻黄素的存在表明轮虫以硅藻和蓝藻为食。出乎意料的是，虽然硅藻在生物量方面强烈主导了微型底栖群落，但 HPLC 结果暗示轮虫选择性地摄取底栖丝状蓝藻。通过这种方式，轮虫每天可以去除相当一部分（高达 28%）的这种蓝藻生物质。利用共聚焦激光扫描显微镜（CLSM）在轮虫体内定位叶绿素荧光，检查了轮虫是否含有共生的含甲藻黄素的蓝藻。CLSM 结果表明，准圆形荧光物体（FO）在轮虫体内均匀分布，而甲藻黄素是丝状蓝藻的生物标志物色素，因此该假设被否定。我们的研究结果还表明，轮虫将β-胡萝卜素（由摄入的藻类提供）转化为echinenone，一种光保护色素。这项研究首次详细描述了轮虫的原位色素含量，清楚地表明，迄今为止，蓝藻作为小型底栖无脊椎动物的食物来源的作用被低估了，值得紧急考虑。
