Reef-building corals form a symbiotic association with photosynthetic dinoflagellates of the family Symbiodiniaceae. This symbiosis is crucial for the maintenance of coral reefs. In this work, we evaluate the effect of light conditions on the transcriptomic response of Symbiodinium CCMR0100 (ITS2 type A4), isolated from the Southwestern Atlantic Ocean endemic Mussismilia braziliensis. We obtained a total of 36,224 transcripts (N50 = 1007 bases, mean GC = 55.7%; ~25 Gb of assembled bases). We observed ecologically relevant transcripts encoding i. the complete antioxidant enzymatic system, ii. the recently described algal dimethylsulfoniopropionate (DMSP) lyase, and iii. The Mycosporine-like aminoacids (MAA) biosynthesis pathway. Cultures maintained in dark and light conditions yielded different transcriptomic profiles, and 48 transcripts were differentially expressed between these treatments. Expression of cytochrome P450 was inhibited by light, suggesting that endoplasmic reticulum monooxygenase activity might play a role in light-independent coral bleaching. Light conditions also triggered the induction of transcripts associated to chromatin condensation and mitosis, consistent with the light dependent progression of Symbiodiniaceae cell cycle. The repression of transcripts associated to the phosphatidylinositol (PI) signaling pathwaysuggests this pathway shall be related to light-induced morphological changes in Symbiodiniaceae cell.

中文翻译：

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对巴西Mussismilia Brasiliensis内共生共生菌的遗传谱的见解。

造礁珊瑚与Symbiodiniaceae科的光合作用鞭毛虫共生。这种共生对于维护珊瑚礁至关重要。在这项工作中，我们评估了光照条件对西南大西洋地方性巴西Mussismilia Braziliensis分离的共生菌CCMR0100（ITS2 A4型）转录组反应的影响。。我们获得了总共36,224个转录本（N50 = 1007个碱基，平均GC = 55.7％；〜25 Gb组装碱基）。我们观察到了编码i的与生态相关的转录本。完整的抗氧化剂酶促体系； ii。最近描述的藻酸二甲基磺基丙酸酯（DMSP）裂解酶，和iii。霉菌素样氨基酸（MAA）的生物合成途径。保持在黑暗和明亮条件下的培养物产生不同的转录组谱，并且在这些处理之间差异表达48个转录物。细胞色素P450的表达受光抑制，表明内质网单加氧酶活性可能在不依赖光的珊瑚褪色中起作用。光照条件也触发了与染色质浓缩和有丝分裂有关的转录本的诱导，与共生菌科细胞周期的光依赖性进展一致。与磷脂酰肌醇（PI）信号转导通路相关的转录物的阻遏提示该通路应与光致共生菌科细胞的形态变化有关。