A physiologic overview of the organ-specific transcriptome of the cattle tick Rhipicephalus microplus

Abstract

To further obtain insights into the Rhipicephalus microplus transcriptome, we used RNA-seq to carry out a study of expression in (i) embryos; (ii) ovaries from partially and fully engorged females; (iii) salivary glands from partially engorged females; (iv) fat body from partially and fully engorged females; and (v) digestive cells from partially, and (vi) fully engorged females. We obtained > 500 million Illumina reads which were assembled de novo, producing > 190,000 contigs, identifying 18,857 coding sequences (CDS). Reads from each library were mapped back into the assembled transcriptome giving a view of gene expression in different tissues. Transcriptomic expression and pathway analysis showed that several genes related in blood digestion and host-parasite interaction were overexpressed in digestive cells compared with other tissues. Furthermore, essential genes for the cell development and embryogenesis were overexpressed in ovaries. Taken altogether, these data offer novel insights into the physiology of production and role of saliva, blood digestion, energy metabolism, and development with submission of 10,932 novel tissue/cell specific CDS to the NCBI database for this important tick species.

De novo assembled salivary gland transcriptome and expression pattern analyses for Rhipicephalus evertsi evertsi Neuman, 1897 male and female ticks

“…The housekeeping functional class contributed to the majority of the composition of the transcriptome (80%) but with lower expression (51%), while the secretory protein functional class represented only 14% of the transcriptome but 46% of the total coverage. This was comparable to the overall description of the secretory category of other salivary gland transcriptomes from Amblyomma americanum , Ixodes ricinus, R. appendiculatus, R. microplus, R. pulchellus , R. sanguineus and R. zambeziensis (between 12 and 63%) 5 , 6 , 16 , 18 – 21 . Nonetheless, the transcriptomes displayed a dynamic range of expression with a few transcripts responsible for most of the expression in the salivary glands.…”

“…This confirmed that the translated proteins from R. evertsi evertsi are generally longer than the other Rhipicephalus transcriptomes, except for Rhipicephalus sanguineus . For an estimate of shared orthologs, the transcriptome was compared with the transcriptomes of Rhipicephalus appendiculatus 16 , Rhipicephalus microplus 17 , 18 , Rhipicephalus pulchellus 19 , R. sanguineus 20 and Rhipicephalus zambeziensis 21 using the reciprocal best hit approach (RBH). Pairwise comparisons indicated that RBHs between transcriptomes are similar, suggesting that the R. evertsi evertsi transcriptome possessed similar numbers of orthologs when compared to existing transcriptomes (Fig.…”

“…The differential expression observed during progression of feeding time resonate with the concept of “sialome switching” where ticks changes their salivary gland protein expression patterns to evade the hosts immune system or as response to specific host species and environmental cues 5 , 7 , 80 . As more differential expression studies are performed this is becoming more apparent 18 , 20 , 81 . Differential expression as means to increase local concentrations at the feeding site and in response to the changing feeding site during the prolonged feeding of ixodids has also been considered 24 .…”

Microbiomes of Blood-Feeding Arthropods: Genes Coding for Essential Nutrients and Relation to Vector Fitness and Pathogenic Infections. A Review

“…More recent investigations have confirmed the selective tissue tropisms of Coxiella sp. for the tick ovary and malpighian tubules in diverse tick species [14,27]. Other reports found Francisella sp.…”

Changes in microbial composition, diversity, and functionality in theAmblyomma maculatummicrobiome following infection withRickettsia parkeri

“…An elegant study by Lejal et al (2021) identified several positive and negative correlations between members of the field-collected, questing Ixodes ricinus microbiome and how some of these interactions are modulated by tick-borne pathogens. It has been established that each tick tissue (organ) undergoes unique responses to specific physiological changes, but it is not known whether these responses also induce changes in the microbial communities residing within these tissues (Franta et al, 2010; Schwarz et al, 2014; Crispell et al, 2016; Kumar et al, 2016; Budachetri et al, 2017; Starck et al, 2018; Tirloni et al, 2020; Kurokawa et al, 2020). In the current study, a high-throughput sequencing approach was utilized to examine microbiome changes throughout the ontogeny of uninfected and pathogen-infected Am.…”