Laboratoire de Physiologie Cellulaire Végétale, Université Grenoble Alpes, CEA, CNRS, INRA, IRIG-LPCV, 38054, Grenoble Cedex 9, France.
INRAE Metagenopolis Unit, Domaine de Vilvert, Bât. 325. 78 352, Jouy-en-Josas, France.
Environ Microbiol. 2020 May;22(5):1901-1916. doi: 10.1111/1462-2920.14978. Epub 2020 Mar 16.
Aurantiochytrium limacinum (Thraustochytriaceae, class Labyrinthulomycetes) is a marine Stramenopile and a pioneering mangrove decomposer. Its life cycle involves a non-motile stage and zoospore production. We observed that the composition of the medium, the presence of amino acids in particular, affects the release of zoospores. Two opposite conditions were defined, one with a cell population mainly composed of zoospores and another one with almost only non-motile cells. In silico allelic frequency analysis and flow cytometry suggest that zoospores and non-motile cells share the same ploidy level and are diploid. Through an RNA-seq approach, the transcriptional reprogramming accompanying the formation of zoospores was investigated, with a particular focus on their lipid metabolism. Based on a differential expression analysis, zoospores are characterized by high motility, very active signal transduction, an arrest of the cell division, a low amino acid metabolism and low glycolysis. Focusing on lipid metabolism, genes involved in lipase activities and peroxisomal β-oxidation are upregulated. qRT-PCR of selected lipid genes and lipid analyses during the life span of zoospores confirmed these observations. These results highlight the importance of the lipid dynamics in zoospores and show the metabolic processes required to use these energy-dense molecules as fuel for zoospore survival during their quest of new territories.
金黄被孢霉（旋壳虫科，Labyrinthulomycetes 类）是一种海洋不等鞭毛类生物，也是一种开创性的红树林分解者。它的生命周期涉及到一个非运动阶段和游动孢子的产生。我们观察到，培养基的组成，特别是氨基酸的存在，会影响游动孢子的释放。定义了两种相反的条件，一种条件下细胞群体主要由游动孢子组成，另一种条件下几乎只有非运动细胞。基于等位基因频率的分析和流式细胞术的分析，游动孢子和非运动细胞具有相同的倍性水平，是二倍体。通过 RNA-seq 方法，研究了伴随游动孢子形成的转录重编程，特别关注它们的脂质代谢。基于差异表达分析，游动孢子的特征是高运动性、非常活跃的信号转导、细胞分裂的停滞、低氨基酸代谢和低糖酵解。聚焦于脂质代谢，参与脂肪酶活性和过氧化物酶体β-氧化的基因被上调。对选定的脂质基因进行 qRT-PCR 和在游动孢子的生命周期中进行脂质分析，证实了这些观察结果。这些结果强调了脂质动态在游动孢子中的重要性，并展示了在游动孢子寻找新领地的过程中，为了生存而利用这些能量密集型分子作为燃料所需的代谢过程。
