title: Helix pelagonesica isolate 42932f RNA-seq
design: RNA was extracted from posterior foot tissues preserved in RNAlater. RNA sequencing libraries were prepared with the NEBNext Ultra II RNA Library Prep Kit for Illumina. mRNAs were enriched with Oligo(dT) beads, fragmented, transcribed to cDNA and enriched by limited-cycle PCR. The libraries were sequenced on the NovaSeq 6000 platform (paired-end, 150 bp). We run rCorrector v1.0.4 on all datasets to correct likely erroneous rare k-mers and removed reads flagged by rCorrector with unfixable_error flag. Then we performed quality and adapter filtering with fastp under the following settings: --detect_adapter_for_pe --cut_front --cut_tail --cut_window_size 4 --cut_mean_quality 25 --qualified_quality_phred 28 --unqualified_percent_limit 40 --n_base_limit 5 --length_required 30 (fastp also removes reads lacking mates after the previous filtering).