De novo assembly and annotation of Hyalomma dromedarii tick (Acari: Ixodidae) sialotranscriptome with regard to gender differences in gene expression

Abstract

BackgroundHard ticks are hematophagous ectoparasites characterized by their long-term feeding. The saliva that they secrete during their blood meal is their crucial weapon against host-defense systems including hemostasis, inflammation and immunity. The anti-hemostatic, anti-inflammatory and immune-modulatory activities carried out by tick saliva molecules warrant their pharmacological investigation. The Hyalomma dromedarii Koch, 1844 tick is a common parasite of camels and probably the best adapted to deserts of all hard ticks. Like other hard ticks, the salivary glands of this tick may provide a rich source of many compounds whose biological activities interact directly with host system pathways. Female H. dromedarii ticks feed longer than males, thereby taking in more blood. To investigate the differences in feeding behavior as reflected in salivary compounds, we performed de novo assembly and annotation of H. dromedarii sialotranscriptome paying particular attention to variations in gender gene expression.ResultsThe quality-filtered Illumina sequencing reads deriving from a cDNA library of salivary glands led to the assembly of 15,342 transcripts. We deduced that the secreted proteins included: metalloproteases, glycine-rich proteins, mucins, anticoagulants of the mandanin family and lipocalins, among others. Expression analysis revealed differences in the expression of transcripts between male and female H. dromedarii that might explain the blood-feeding strategies employed by both genders.ConclusionsThe annotated sialome of H. dromedarii helps understand the interaction of tick-host molecules during blood-feeding and can lead to the discovery of new pharmacologically active proteins of ticks of the genus Hyalomma.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-2874-9) contains supplementary material, which is available to authorized users.

De novo assembly and analysis of the transcriptome of the Dermacentor marginatus genes differentially expressed after blood-feeding and long-term starvation

“…The purpose of the RNA-seq analysis was to obtain gene sequences and identify differentially expressed genes of D. marginatus female adults after blood-feeding and long-term starvation regarding the significant role of female adult that plays in feeding large amount of blood and producing thousands of eggs per individual [ 35 ]. Another reason choosing females only for the RNA-seq analysis was to minimize the gene expression difference profiled by sexual distinction [ 36 , 37 ].…”

A transcriptome and proteome of the tick Rhipicephalus microplus shaped by the genetic composition of its hosts and developmental stage

“…Regarding the combined timepoint profiles of expression of transcripts encoding these proteins in males and females of R. zambeziensis, they were also similar to those seen in R. microplus adults with the exception again of metalloproteases, but also of evasins, 8.9 kDa protein family and mucins, where females presented greater representation of these transcripts than males. We have already pointed out above the possible explanation for the discrepancy between levels of expression of IGBP in the sialotranscriptome generated in the present study and in that of males of the two-or three-host tick H. dromedarii that can infest cattle as well as camelids 40,41 . At present it is not possible to ascribe a role for secreted salivary protein families in determining the number of hosts different species of ticks have in their life cycles.…”

“…IGBPs have been found in all male hard ticks examined to date, including in Ixodes scapularis, which frequently mates off its hosts. The exception is Hyalomma dromedarii 40 , where transcripts for IGBPs were not found in the salivary gland transcriptomes from males and females feeding on camels and a partial sequence was obtained for a single type of IGBP in the corresponding proteome. Camelids of the Saharan regions are the natural hosts of H. dromedarii 41 , mammals which produce mainly single chain antibodies, instead of conventional antibodies.…”

De Novo Assembly and Analysis of Transcriptome of the Dermacentor Marginatus Genes Differentially Expressed After Blood Feeding and Long-term Starvation

“…The purpose of the RNA-seq analysis was to identify differentially expressed genes of D. marginatus female adults after blood feeding and long term starvation regarding the signi cant role of female adult that plays in feeding large amount of blood and producing thousands of eggs per individual [29]. Another reason choosing females only for the RNA-seq analysis was to minimize the gene expression difference pro led by sexual distinction [30,31].…”