Mapping and understanding the function of RNA in octopus brain

Coleoid cephalopods possess a highly complex nervous system and a rich behavioral repertoire that is unique within the invertebrates and is comparable to – but evolved independently from – the vertebrates (Shigeno et al. 2018). To explain this complexity, previous studies have implicated a unusually high level of mRNA editing in transcripts expressed in both the octopus and squid nervous system (Albertin et al. 2015; Alon et al. 2015; Liscovitch-Brauer et al. 2017). We have sequenced RNA across 18 tissues from the octopus O. vulgaris, and analyzed the extent of mRNA isoform usage as well as the expression of microRNAs in the nervous system in comparison to non-neuronal tissues. Overall design: Messenger RNA and small RNA profiles of 18 tissues of a common octopus (Octopus vulgaris). In this study, the replicates are present for small RNA expression dataset, where the same set of 18 tissues has been analyzed using 2 different library preparation protocols. With few exceptions, there are matching polyA RNA-seq and totalRNA-seq datasets for the tissues in the study. Finally, the same tissue combinations have been profiled by both FLAM-seq and Iso-seq full-length mRNA sequencing methods.

鞘亚纲头足类（Coleoid cephalopods）拥有极为复杂的神经系统与丰富的行为谱，这一特征在无脊椎动物中独树一帜，可与脊椎动物的相应特征相媲美，但其演化路径完全独立于脊椎动物（Shigeno等，2018）。为阐释这一复杂性状的演化起源，既往研究指出，章鱼与鱿鱼神经系统中表达的转录本存在异常高水平的mRNA编辑（mRNA editing）现象（Albertin等，2015；Alon等，2015；Liscovitch-Brauer等，2017）。本研究对普通章鱼（Octopus vulgaris，O. vulgaris）的18种组织进行了RNA测序，并对比分析了神经系统与非神经元组织中的mRNA可变剪接异构体（mRNA isoform）使用程度，以及微小RNA（microRNA）的表达水平。

整体实验设计：
普通章鱼（Octopus vulgaris）18种组织的信使RNA（messenger RNA，mRNA）与小RNA表达谱。本研究的小RNA表达数据集包含重复样本：针对同一组18种组织，采用两种不同的文库制备方案完成了测序分析。除极少数例外情况外，本研究涉及的所有组织均配有匹配的聚腺苷酸RNA测序（polyA RNA-seq）与总RNA测序（totalRNA-seq）数据集。最后，针对相同的组织组合，本研究同时采用了FLAM-seq与Iso-seq两种全长mRNA测序方法进行了表达谱分析。