The tick subgenus Afrixodes Morel 1966 (Ixodidae) is distributed in sub-Saharan Africa. It consists of about 60 species which are described based on a few specimens and/or only some developmental stages, mostly adults. Because of this, the diagnosis of the African species of Ixodes is in many aspects complicated. Ixodes rasus Neumann 1899 is a common species, widely distributed in tropical and subtropical moist broadleaved forests in central Africa, whose morphology remains poorly described. We redescribe the adults of the species and provide molecular data for 16S rDNA based on three questing females and one male collected in the Central African Republic. Both sexes have an anal groove rounded and closed. The female has syncoxae on coxae I to III, a dental formula of 2/2, and long, curved auriculae. The male has moderate syncoxae on coxae I-III, coxae I-II carry one single internal spur each: coxae III and IV unarmed. The cornua are absent in the male, and the auriculae are small lobes. The male pregenital plate is longer than broad, with an anterior margin widely rounded; the median plate is large and clearly divergent posteriorly, with adanal plates fused posteriorly to the anus, and a dental formula of 4/4 (one row of 5/5). The molecular features of 16S rDNA place I. rasus near I. aulacodi (the only other Afrixodes species for which 16S rDNA is available) and near I. turdus and I. frontalis; two species of ticks of the Palearctic region, which commonly infest birds. The paucity of data regarding the subgenus Afrixodes makes it necessary to provide reliable and comparable re-descriptions of several species, as well as description of the immature stages for many of the currently known taxa.
- MeSH
- fylogeneze MeSH
- Ixodidae anatomie a histologie klasifikace genetika MeSH
- klíště anatomie a histologie klasifikace genetika MeSH
- larva anatomie a histologie genetika MeSH
- nymfa anatomie a histologie genetika MeSH
- RNA ribozomální 16S MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Středoafrická republika MeSH
Ticks are vectors of pathogens affecting human and animal health worldwide. Nevertheless, the ecological and evolutionary interactions between ticks, hosts, and pathogens are largely unknown. Here, we integrated a framework to evaluate the associations of the tickIxodes ricinuswith its hosts and environmental niches that impact pathogen circulation. The analysis of tick-hosts association suggested that mammals and lizards were the ancestral hosts of this tick species, and that a leap to Aves occurred around 120 M years ago. The signature of the environmental variables over the host's phylogeny revealed the existence of two clades of vertebrates diverging along a temperature and vegetation split. This is a robust proof that the tick probably experienced a colonization of new niches by adapting to a large set of new hosts, Aves. Interestingly, the colonization of Aves as hosts did not increase significantly the ecological niche ofI. ricinus, but remarkably Aves are super-spreaders of pathogens. The disparate contribution of Aves to the tick-host-pathogen networks revealed thatI. ricinusevolved to maximize habitat overlap with some hosts that are super-spreaders of pathogens. These results supported the hypothesis that large host networks are not a requirement of tick survival but pathogen circulation. The biological cost of tick adaptation to non-optimal environmental conditions might be balanced by molecular mechanisms triggered by the pathogens that we have only begun to understand.
- MeSH
- biologická adaptace MeSH
- druhová specificita MeSH
- ekologie metody MeSH
- interakce hostitele a patogenu MeSH
- ještěři parazitologie MeSH
- klíšťata mikrobiologie parazitologie fyziologie MeSH
- klíště klasifikace parazitologie fyziologie MeSH
- lidé MeSH
- nemoci přenášené klíšťaty parazitologie přenos MeSH
- obratlovci klasifikace parazitologie MeSH
- ptáci klasifikace parazitologie MeSH
- savci klasifikace parazitologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This study assessed the parasitization of cavity-nesting birds and ground-nesting/foraging birds with larvae and nymphs of two Ixodes species, Ixodes ricinus and Ixodes arboricola. Totals of 679 (52.3%) I. ricinus and 619 (47.7%) I. arboricola ticks were collected from 15 species of passerine birds which were caught during the nesting and non-nesting periods of 2003-2006, in the south-eastern part of the Czech Republic, the Drahanská Vrchovina Uplands. In the non-nesting period from October to March, 6.8% (101/1492) of birds were infested with ticks, mainly with I. arboricola larvae. In the non-nesting period, the average intensity of infestation by I. arboricola and I. ricinus was 8.5 and 1.5 individuals per infested bird, respectively. In the nesting period from April to June, 21.6% (50/232) of birds were infested by both tick species but mainly with I. ricinus nymphs. The average intensity of infestation by I. ricinus and I. arboricola was 13.3 and 10.8 individuals per infested bird, respectively. Altogether, 23.2% of the infested birds were parasitized by both immature life stages of one or both tick species. From an enzootic perspective, co-feeding and co-infestation of I. ricinus and I. arboricola subadults on passerine birds might happen and may be important for the dissemination of tick-borne agents.
- MeSH
- infestace klíšťaty epidemiologie parazitologie veterinární MeSH
- interakce hostitele a parazita MeSH
- klíště klasifikace fyziologie MeSH
- koinfekce epidemiologie parazitologie MeSH
- larva fyziologie MeSH
- nemoci ptáků epidemiologie parazitologie MeSH
- nymfa fyziologie MeSH
- ptáci parazitologie fyziologie MeSH
- roční období MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika epidemiologie MeSH
Ixodes ricinus is a tick that transmits the pathogens of Lyme and several arboviral diseases. Pathogens invade the tick midgut, disseminate through the hemolymph, and are transmitted to the vertebrate host via the salivary glands; subverting these processes could be used to interrupt pathogen transfer. Here, we use massive de novo sequencing to characterize the transcriptional dynamics of the salivary and midgut tissues of nymphal and adult I. ricinus at various time points after attachment on the vertebrate host. Members of a number of gene families show stage- and time-specific expression. We hypothesize that gene expression switching may be under epigenetic control and, in support of this, identify 34 candidate proteins that modify histones. I. ricinus-secreted proteins are encoded by genes that have a non-synonymous to synonymous mutation rate even greater than immune-related genes. Midgut transcriptome (mialome) analysis reveals several enzymes associated with protein, carbohydrate, and lipid digestion, transporters and channels that might be associated with nutrient uptake, and immune-related transcripts including antimicrobial peptides. This publicly available dataset supports the identification of protein and gene targets for biochemical and physiological studies that exploit the transmission lifecycle of this disease vector for preventative and therapeutic purposes.
- MeSH
- anotace sekvence MeSH
- časové faktory MeSH
- fylogeneze MeSH
- genetická transkripce * MeSH
- klíště klasifikace genetika MeSH
- orgánová specificita genetika MeSH
- polymorfismus genetický MeSH
- shluková analýza MeSH
- slinné žlázy metabolismus MeSH
- stanovení celkové genové exprese MeSH
- střeva metabolismus MeSH
- transkriptom MeSH
- výpočetní biologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Intramural MeSH
BACKGROUND: Ticks are blood-sucking arthropods and a primary function of tick salivary proteins is to counteract the host's immune response. Tick salivary Kunitz-domain proteins perform multiple functions within the feeding lesion and have been classified as venoms; thereby, constituting them as one of the important elements in the arms race with the host. The two main mechanisms advocated to explain the functional heterogeneity of tick salivary Kunitz-domain proteins are gene sharing and gene duplication. Both do not, however, elucidate the evolution of the Kunitz family in ticks from a structural dynamic point of view. The Red Queen hypothesis offers a fruitful theoretical framework to give a dynamic explanation for host-parasite interactions. Using the recent salivary gland Ixodes ricinus transcriptome we analyze, for the first time, single Kunitz-domain encoding transcripts by means of computational, structural bioinformatics and phylogenetic approaches to improve our understanding of the structural evolution of this important multigenic protein family. RESULTS: Organizing the I. ricinus single Kunitz-domain peptides based on their cysteine motif allowed us to specify a putative target and to relate this target specificity to Illumina transcript reads during tick feeding. We observe that several of these Kunitz peptide groups vary in their translated amino acid sequence, secondary structure, antigenicity, and intrinsic disorder, and that the majority of these groups are subject to a purifying (negative) selection. We finalize by describing the evolution and emergence of these Kunitz peptides. The overall interpretation of our analyses discloses a rapidly emerging Kunitz group with a distinct disulfide bond pattern from the I. ricinus salivary gland transcriptome. CONCLUSIONS: We propose a model to explain the structural and functional evolution of tick salivary Kunitz peptides that we call target-oriented evolution. Our study reveals that combining analytical approaches (transcriptomes, computational, bioinformatics and phylogenetics) improves our understanding of the biological functions of important salivary gland mediators during tick feeding.
- MeSH
- fylogeneze MeSH
- klíště chemie klasifikace genetika metabolismus MeSH
- molekulární evoluce * MeSH
- proteiny členovců chemie genetika metabolismus MeSH
- sekvence aminokyselin MeSH
- sekvenční seřazení MeSH
- slinné proteiny a peptidy chemie genetika metabolismus MeSH
- terciární struktura proteinů MeSH
- transkriptom * MeSH
- výpočetní biologie MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- klíště klasifikace parazitologie MeSH
- kontrola klíšťat metody MeSH
- nymfa parazitologie patogenita MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Geografické názvy
- Česká republika MeSH
- MeSH
- buňky NK imunologie MeSH
- klíště imunologie klasifikace MeSH
- lidé MeSH
- slinné žlázy imunologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- MeSH
- klíště genetika chemie klasifikace MeSH
- molekulární evoluce MeSH
- uhlovodíky genetika MeSH
- Geografické názvy
- Španělsko MeSH
