RNA-seq analysis of the salivary glands and midgut of the Argasid tick Ornithodoros rostratus

Abstract

Ornithodoros rostratus is a South American argasid tick which importance relies on its itchy bite and potential as disease vector. They feed on a wide variety of hosts and secrete different molecules in their saliva and intestinal content that counteract host defences and help to accommodate and metabolize the relatively large quantity of blood upon feeding. The present work describes the transcriptome profile of salivary gland (SG) and midgut (MG) of O. rostratus using Illumina sequencing. A total of 8,031 contigs were assembled and assigned to different functional classes. Secreted proteins were the most abundant in the SG and accounted for ~67% of all expressed transcripts with contigs with identity to lipocalins and acid tail proteins being the most representative. On the other hand, immunity genes were upregulated in MG with a predominance of defensins and lysozymes. Only 10 transcripts in SG and 8 in MG represented ~30% of all RNA expressed in each tissue and one single contig (the acid tail protein ORN-9707) represented ~7% of all expressed contigs in SG. Results highlight the functional difference of each organ and identified the most expressed classes and contigs of O. rostratus SG and MG.

Quantitative Visions of Reality at the Tick-Host Interface: Biochemistry, Genomics, Proteomics, and Transcriptomics as Measures of Complete Inventories of the Tick Sialoverse

“…To date only one salivary gland transcriptome have been described for soft ticks from next-generation sequencing data, namely for Ornithodoros rostratus (Aragao, 1911) (Araujo et al, 2019 ). Salivary glands and midguts were collected from fourth instar nymphs that were unfed or 1 and 4 day fed.…”

Immunity to vector saliva is compromised by short sand fly seasons in endemic regions with temperate climates

“…RnA extraction, library preparation and sequencing. RNA preparation, library construction and sequencing were performed essentially as described previously 61 . Briefly, a pool of 30 salivary gland pairs from female P. kandelakii were dissected, placed in RNAlater and kept at 4 °C for 48 h before being transferred to −70 °C until RNA extraction.…”

“…Customized bioinformatic analysis was performed as described elsewhere 61 . Reads were trimmed of low-quality regions (<10), and only those with an average quality of 20 or more were used, comprising a total of 19,431,950 high-quality reads.…”

“…Reads were trimmed of low-quality regions (<10), and only those with an average quality of 20 or more were used, comprising a total of 19,431,950 high-quality reads. RPKM values were mapped to a spreadsheet (presented as Supplemental File 1) containing the assembled Pkan sequence names organized by categories as previously described 61 and with columns highlighting their best match to GO, PFAM, KOG, REFSEQ-INVERTEBRATE, Smart, SWISSPROT databases and to a custom database obtained from a NCBI protein search using the key words "diptera [organism]". The spreadsheet also contains information on the presence of predicted signal peptide and cleavage sites (Supplemental File 1).…”

Catalogue of stage-specific transcripts in Ixodes ricinus and their potential functions during the tick life-cycle

“…Due to an increase in its epidemiological importance, I. ricinus has become a species featured in many recent transcriptomic studies, the majority of them focused on the transcription in salivary glands and/or midgut, which are the key organs in the tick-borne pathogens' lifecycle. Studying these organs in response to blood-feeding can be instrumental for the identification of factors that underlie survival and dissemination of pathogens within their vector and their transmission into the final host [24,[31][32][33][34][35][36][37] . More specifically, expression analyses using tick haemocytes, the main actors in tick immunity, can unveil the character of the immunity barrier for tick-borne pathogens [29].…”