Effect of an altitudinal gradient on the morphology, molecular identification and distribution of Rhipicephalus linnaei in Veracruz, Mexico.

Studies of morphological and genetic variation in vector populations across environmental gradients can help researchers to estimate species' responses to climate change scenarios and the potential risk of disease-causing pathogen expansion, which impacts negatively on human health. In this study, we analysed the effect of altitudinal gradients on the phenotypic response of the hard tick of medical and veterinary importance, Rhipicephalus sanguineus sensu lato (s.l.). Specimens of R. sanguineus s.l. were collected from host animals in one of Mexico's regions with high climatic heterogeneity (Veracruz), and geometric morphometric theory was employed to assess the response of three morphological characters to the altitudinal gradient. Additionally, genetic similarity data were provided, and ecological niche models were used to project the climatic distribution in the region. Our results demonstrate that the shape and size of ticks respond to altitude. Molecular identification indicate that all analysed samples correspond to the tropical lineage recently named Rhipicephalus linnaei. According to ecological niche models, the mean annual temperature contributes significantly to the spatial distribution of this tick species, with areas of higher suitability in the mountainous region. These changes in morphological structure and the presence of ticks at higher altitudinal gradients suggest that R. linnaei has a high potential for adaptation. Due to the variability of ecosystems in the state of Veracruz, our results could be valuable in assessing the response of this tick in a changing environment, aiding in predicting future scenarios in the distribution and abundance of this species.

Predicting the northward expansion of tropical lineage Rhipicephalus sanguineus sensu lato ticks in the United States and its implications for medical and veterinary health.

The tropical lineage within the Rhipicephalus sanguineus species complex is cause for growing concern in the U.S. based on its prominent role in creating and perpetuating multiple recently identified outbreaks of Rocky Mountain spotted fever in the southwestern United States and northern Mexico. This lineage is undergoing a northward range expansion in the United States, necessitating the need for enhanced surveillance for Rh. sanguineus. To inform more focused surveillance efforts we use species distribution models (SDMs) to predict current (2015-2019) and future (2021-2040) habitat for the tropical lineage. Models using the MaxEnt algorithm were informed using geolocations of ticks genetically confirmed to be of the tropical lineage, for which data on 23 climatic and ecological variables were extracted. Models predicted that suitability was optimal where temperatures are relatively warm and stable, and there is minimal precipitation. This translated into habitat being predicted along much of the coast of southern states including California, Texas, Louisiana, and Florida. Although the endophilic nature of tropical Rh. sanguineus somewhat violates the assumptions of SDMs, our models correctly predicted known locations of this tick and provide a starting point for increased surveillance efforts. Furthermore, we highlight the importance of using molecular methods to distinguish between ticks in the Rh. sanguineus species complex.

Genetic diversity and population structure of Rhipicephalus sanguineus sensu lato across different regions of Colombia.

BACKGROUND: There has been a long-standing debate over the taxonomic status of Rhipicephalus sanguineus sensu lato. Different studies worldwide have reported the occurrence of different well-defined lineages, in addition to Rhipicephalus sanguineus sensu stricto. To date, there are very few studies examining the diverse aspects of this tick in Colombia. We assessed the population structure and genetic diversity of R. sanguineus s.l. in eight departmental regions across Colombia. METHODS: A total of 170 ticks were collected from dogs in different departments of Colombia. All specimens were morphologically compatible with R. sanguineus s.l. and subjected to genetic analysis. DNA sequences were obtained for the 12S rDNA, cytochrome oxidase I (COI) and internal transcribed spacer 2 (ITS2) markers. A concatenated set of all mitochondrial markers was also constructed. Next, maximum likelihood phylogenetic trees were constructed using the sequences generated herein and sequences available in GenBank. Finally, we assessed different summary statistics and analysed population structure and divergence with Fst and Dxy and demographic changes with Tajima's D and Fu and Li's statistical tests. RESULTS: Analysis of the 12S rDNA and COI revealed that all R. sanguineus s.l. specimens collected across different regions of Colombia clustered within the tropical lineage. Micro-geographical analyses showed that the tick population from Amazonas formed a distinct cluster separated from the other sequences, with moderate Fst and Dxy values. However, no signs of a robust population structure were found within the country. The results of Fu's FS tests, together with the haplotype networks and diversity values, signal a possible population expansion of this tick species in Colombia. CONCLUSIONS: Evidence provided herein supports the tropical lineage as the main circulating lineage in Colombia, exhibiting a general lack of genetic structure except for the Amazonas region.

Analysis on the prokaryotic microbiome in females and embryonic cell cultures of Rhipicephalus sanguineus tropical and temperate lineages from two specific localities in Brazil / Análise do microbioma procarionte de fêmeas e cultura celular embrionária de Rhipicephalus sanguineus linhagens tropical e temperada de duas localidades no Brasil

Two lineages of Rhipicephalus sanguineus are known in Brazil: the temperate or southern and the tropical or northern populations. The distribution patterns of both lineages of R. sanguineus have epidemiological implications that can affect vectorial competence concerning Ehrlichia canis, the agent of canine monocytic ehrlichiosis. Intending to identify the microbiomes of both lineages and compare microorganisms in R. sanguineus, we used the 16S rRNA (V4-V5 region) gene-based metataxonomic approach, through NGS sequencing on the MiSeq Illumina platform. We selected specimens of females from the environment and samples of primary embryonic cell cultures, from both lineages, and this was the first study to investigate the prokaryotic microbiome in tick cell cultures. The results showed that many bacterial taxa detected in the samples were typical members of the host environment. A significant diversity of microorganisms in R. sanguineus females and in embryonic cell cultures from both lineages was found, with emphasis on the presence of Coxiella in all samples, albeit in different proportions. The Coxiella species present in the two lineages of ticks may be different and may have co-evolved with them, thus driving different patterns of interactions between ticks and the pathogens that they can harbor or transmit to vertebrate hosts.(AU)

Duas linhagens de Rhipicephalus sanguineus são conhecidas no Brasil: populações da linhagem temperada ou do sul, e tropical ou do norte. Os padrões de distribuição de ambas as linhagens de R. sanguineus têm implicações epidemiológicas, podendo afetar a competência vetorial de Ehrlichia canis, o agente etiológico da erliquiose monocítica canina. Com a intenção de identificar os microbiomas de ambas as linhagens e comparar microrganismos de R. sanguineus, foi utilizada a metataxonomia, baseada no gene 16S rRNA (região V4-V5), por meio do sequenciamento de nova geração na plataforma MiSeq Illumina. Foram selecionadas amostras de fêmeas do ambiente e cultivo primário de células embrionárias, considerando-se as duas linhagens conhecidas do Brasil. Este é o primeiro estudo que investiga o microbioma procariótico de células de cultura de carrapato. Os resultados mostram que muitos grupos de bactérias detectadas nas amostras são membros típicos do ambiente do hospedeiro. Uma diversidade significativa de microrganismos em fêmeas e cultura de células embrionárias nas duas linhagens de R. sanguineus foi encontrada, com ênfase na presença de Coxiella em todas as amostras, ainda que em diferentes proporções. Possivelmente, as espécies de Coxiella presentes nas duas linhagens de carrapatos são diferentes e co-evoluíram com essas linhagens, conduzindo a diferentes padrões de interação entre carrapatos e patógenos que podem abrigar ou transmitir aos hospedeiros vertebrados.(AU)

Germ cells: a useful tool for the taxonomy of Rhipicephalus sanguineus s.l. and species of the Amblyomma cajennense complex (Acari: Ixodidae).

The systematics of several ticks species (Acari: Ixodidae) remains controversial. Many species, including those of the Amblyomma cajennense complex and Rhipicephalus sanguineus s.l., are given special attention since they are cryptic species complexes and are also important in human and veterinary medicine. The A. cajennense complex was recently reorganized into six valid species, among which Amblyomma patinoi and Amblyomma mixtum have been confirmed in Colombia. On the other hand, the taxonomic status of R. sanguineus s.l. is controversial since it is a cosmopolitan cryptic species complex with a high reproductive capacity and a broad range of hosts (including man). To address this challenge, the germ cells of male ticks display a diverse morphology that offers novel opportunities for taxonomy. This study describes the events of spermatogenesis in A. mixtum and R. sanguineus s.l. individuals collected during active feeding on domestic hosts in the department of Caldas, Colombia. The individuals were identified using dichotomous keys and through PCR amplification of a fragment of the mitochondrial 16S ribosomal DNA gene. The male reproductive systems of A. mixtum and R. sanguineus s.l. were fixed in 2.5% glutaraldehyde for 48 h and dehydrated in increasing dilutions of ethanol. The samples were then embedded and mounted in historesin to obtain sections of 3 µm that were stained with hematoxylin-eosin (HE), photographed, and visualized through optical microscopy. The results show that the morphology of mature germ cells displays excellent diagnostic traits that can be used for tick taxonomy.

Biological compatibility between two temperate lineages of brown dog ticks, Rhipicephalus sanguineus (sensu lato).

BACKGROUND: The brown dog tick Rhipicephalus sanguineus (sensu stricto) is reputed to be the most widespread tick of domestic dogs worldwide and has also been implicated in the transmission of many pathogens to dogs and humans. For more than two centuries, Rh. sanguineus (s.s.) was regarded as a single taxon, even considering its poor original description and the inexistence of a type specimen. However, genetic and crossbreeding experiments have indicated the existence of at least two distinct taxa within this name: the so-called "temperate" and "tropical" lineages of Rh. sanguineus (sensu lato). Recent genetic studies have also demonstrated the existence of additional lineages of Rh. sanguineus (s.l.) in Europe and Asia. Herein, we assessed the biological compatibility between two lineages of Rh. sanguineus (s.l.) found in southern Europe, namely Rhipicephalus sp. I (from Italy) and Rhipicephalus sp. II (from Portugal). METHODS: Ticks morphologically identified as Rh. sanguineus (s.l.) were collected in southern Portugal and southern Italy. Tick colonies were established and crossbreeding experiments conducted. Morphological, biological and genetic analyses were conducted. RESULTS: Crossbreeding experiments confirmed that ticks from the two studied lineages were able to mate and generate fertile hybrids. Hybrid adult ticks always presented the same genotype of the mother, confirming maternal inheritance of mtDNA. However, larvae and nymphs originated from Rhipicephalus sp. I females presented mtDNA genotype of either Rhipicephalus sp. I or Rhipicephalus sp. II, suggesting the occurrence of paternal inheritance or mitochondrial heteroplasmy. While biologically compatible, these lineages are distinct genetically and phenotypically. CONCLUSIONS: The temperate lineages of Rh. sanguineus (s.l.) studied herein are biologically compatible and genetic data obtained from both pure and hybrid lines indicate the occurrence of paternal inheritance or mitochondrial heteroplasmy. This study opens new research avenues and raises question regarding the usefulness of genetic data and crossbreeding experiments as criteria for the definition of cryptic species in ticks.

Geographical distribution and phylogenetic analysis of Rhipicephalus sanguineus sensu lato in northern and central Chile.

The presented study analyzed the presence and geographical distribution of the tropical and temperate lineages of Rhipicephalus sanguineus sensu lato in Chile. R. sanguineus s.l. ticks were collected from dogs at 14 sites in northern and central Chile for morphological and genetic analysis based on the 16S rDNA gene. Phylogenetic studies proved the existence of both, the tropical and the temperate lineages. The former was represented by a single haplotype and occurred in the far north; the latter included four haplotypes and was observed from the Tarapacá Region southwards. In four sites at latitudes from 20°S to 22°S, both lineages were found to coexist. Our study discovered for the first time the existence of the tropical lineage in Chile and demonstrated that distributions of the tropical and temperate lineages overlap, forming a transitional zone of approximately 200 km in northern coastal Chile.

Possible Northward Introgression of a Tropical Lineage of Rhipicephalus sanguineus Ticks at a Site of Emerging Rocky Mountain Spotted Fever.

Increasing rates of Rocky Mountain spotted fever (RMSF) in the southwestern United States and northern Mexico underscore the importance of studying the ecology of the brown dog tick, Rhipicephalus sanguineus, the vector in that region. This species is reported to comprise distinct tropical and temperate lineages that may differ in vectorial capacity for RMSF and are hypothesized to be limited in their geographical range by climatic conditions. In this study, lineage was determined for ticks from 9 locations in California, Arizona, and Mexico by DNA sequencing of 12S, 16S, and D-loop ribosomal RNA. As expected, sites in northern California and eastern Arizona had temperate-lineage ticks, and phylogenetic analysis revealed considerable genetic variability among these temperate-lineage ticks. However, tropical-lineage ticks extended north from Oaxaca, Mexico were well established along the entire border from San Diego, California to western Arizona, and were found as far north as Lytle Creek near Los Angeles, California (a site where both lineages were detected). Far less genetic variability in the tropical lineage despite the large geographical distances is supportive of a hypothesis of rapid northward expansion. Discovery of the tropical lineage north of the identified climatic limitations suggests that more work is needed to characterize this tick's ecology, vectorial capacity, expansion, possible evolution, and response to climate change.

Rocky Mountain spotted fever in Mexico: past, present, and future.

Rocky Mountain spotted fever, a tick-borne zoonosis caused by Rickettsia rickettsii, is among the most lethal of all infectious diseases in the Americas. In Mexico, the disease was first described during the early 1940s by scientists who carefully documented specific environmental determinants responsible for devastating outbreaks in several communities in the states of Sinaloa, Sonora, Durango, and Coahuila. These investigators also described the pivotal roles of domesticated dogs and Rhipicephalus sanguineus sensu lato (brown dog ticks) as drivers of epidemic levels of Rocky Mountain spotted fever. After several decades of quiescence, the disease re-emerged in Sonora and Baja California during the early 21st century, driven by the same environmental circumstances that perpetuated outbreaks in Mexico during the 1940s. This Review explores the history of Rocky Mountain spotted fever in Mexico, current epidemiology, and the multiple clinical, economic, and social challenges that must be considered in the control and prevention of this life-threatening illness.

Ultrastructural Morphology and Molecular Analyses of Tropical and Temperate "Species" of Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) in Brazil.

The Rhipicephalus sanguineus (Latreille) complex (Acari:Ixodidae) is composed of species with intra- and interspecific morphological variation that make their diagnosis difficult. In the present study, male specimens of the R. sanguineus complex were collected from dogs in six districts of three regions of Brazil and submitted to molecular and scanning electron microscopy (SEM) analyses. Analysis of COX1 gene, 12S rDNA, and D-loop rDNA shows that ticks classified as R. sanguineus form two different clades. Morphological comparisons using SEM found adult males to exhibit morphological differences in Haller's organ, festoons, and adanal, spiracular, and genital plates, with the last having potential usefulness in distinguishing male specimens of the complex.

Genetic characterization of Rhipicephalus sanguineus (sensu lato) ticks from dogs in Portugal.

BACKGROUND: The taxonomic status of the brown dog tick Rhipicephalus sanguineus (sensu stricto) is a subject of on-going debate; there is a consensus that populations of this tick species should be referred to as R. sanguineus (sensu lato) until its taxonomic status is resolved. Recent genetic studies revealed the existence of more than one lineage of R. sanguineus (s.l.) in temperate countries. In this study, we assessed the genetic identity of ticks collected from rural dogs living in several areas located in all major geographical regions of Portugal. METHODS: A total of 347 ticks were collected from rural dogs living in different regions of Portugal. These ticks were morphologically identified and partial mitochondrial 16S rRNA gene sequences (~300 bp) were obtained from representative specimens. RESULTS: The ticks were morphologically identified as Ixodes ricinus (seven males and 27 females), Rhipicephalus bursa (one male), Rhipicephalus pusillus (one female) and R. sanguineus (s.l.) (two larvae, 101 nymphs, 108 males and 100 females). Partial mitochondrial 16S rRNA gene sequences were obtained from 58 R. sanguineus (s.l.) specimens, and all of them were genetically identified as belonging to the so-called temperate lineage of R. sanguineus (s.l.) CONCLUSIONS: These results strongly suggest that the temperate species of R. sanguineus (s.l.) is the only representative of this tick group found on dogs in Portugal. It also adds weight to the hypothesis that Rhipicephalus turanicus is not present in this country, although further investigations are necessary to confirm this.

Prevalence and infection intensity of Rickettsia massiliae in Rhipicephalus sanguineus sensu lato ticks from Mendoza, Argentina.

Rickettsia massiliae belongs to the spotted fever group and in the New World is commonly associated with the brown dog tick, Rhipicephalus sanguineus. Herein we investigate the presence of R. massiliae in Rh. sanguineus sensu lato ticks in a location near the Andean foothills (Mendoza, Argentina), to provide a prevalence estimate and to assess the infection intensity of this pathogen. Rickettsia massiliae infection was found in 5.1% of the Rh. sanguineus s.l ticks analyzed, all with high infection intensities. Molecular analysis determined that all R. massiliae-infected Rh. sanguineus s.l. ticks belonged to the temperate lineage.

Morphological and genetic diversity of Rhipicephalus sanguineus sensu lato from the New and Old Worlds.

BACKGROUND: The taxonomic status of the brown dog tick (Rhipicephalus sanguineus sensu stricto), which has long been regarded as the most widespread tick worldwide and a vector of many pathogens to dogs and humans, is currently under dispute. METHODS: We conducted a comprehensive morphological and genetic study of 278 representative specimens, which belonged to different species (i.e., Rhipicephalus bursa, R. guilhoni, R. microplus, R. muhsamae, R. pusillus, R. sanguineus sensu lato, and R. turanicus) collected from Europe, Asia, Americas, and Oceania. After detailed morphological examination, ticks were molecularly processed for the analysis of partial mitochondrial (16S rDNA, 12S rDNA, and cox1) gene sequences. RESULTS: In addition to R. sanguineus s.l. and R. turanicus, three different operational taxonomic units (namely, R. sp. I, R. sp. II, and R. sp. III) were found on dogs. These operational taxonomical units were morphologically and genetically different from R. sanguineus s.l. and R. turanicus. Ticks identified as R. sanguineus s.l., which corresponds to the so-called "tropical species" (= northern lineage), were found in all continents and genetically it represents a sister group of R. guilhoni. R. turanicus was found on a wide range of hosts in Italy and also on dogs in Greece. CONCLUSIONS: The tropical species and the temperate species (= southern lineage) are paraphyletic groups. The occurrence of R. turanicus in the Mediterranean region is confirmed. A consensual re-description of R. sanguineus s.s. and R. turanicus will be necessary to solve the taxonomic problems within the so-called R. sanguineus group.

Caracterização e análise da diversidade dos genes codificadores das proteínas GP19 e GP36 de Ehrlichia canis (Donatien e Lestoquard, 1935) detectada em sangue total de cães (Canis familiaris) naturalmente infectados

[...] O produto obtido foi sequenciado e a análise da similaridade realizada apresentou identidade com valores variando entre 95,7% e 100%. A segunda etapa foi a análise da sequencia do gene codificador das proteínas gp19 e gp36, que foi realizada utilizando iniciadores específicos intergênicos e apenas 11 seqüências codificadoras da gp19 e 2 codificadoras da gp36 foram amplificadas. As sequências codificadoras da gp19 permaneceram altamente conservadas e as de gp36 apresentaram características semelhantes a isolados diferentes (56C semelhante aos genotipos novos de Formosa e 70C semelhante ao genotipo São Paulo e demais isolados do mundo) Após esse estudo, a análise de significância entre os sinais clínicos e achados hematológicos foi determinada por meio de tabelas de contingência através da prova do quiquadrado e Fisher exato. Dos animais positivos em Duque de Caxias, os sinais clínicos que foram significativos foram apatia, anorexia e perda de peso. Maricá e Cachoeiras de Macacu tiveram como sinais clínicos significativos a dispnéia. Observando a queixa principal relacionada ao animal 56C e seus sinais clínicos e hematológicos, nota-se que são característicos de uma possível infecção por E. canis o que não acontece com o animal 70C. Considerando-se em conjunto as diferentes características clínicas ehematológicas dos dois animais, as diferenças nas seqüências do gene codificador da proteína gp36 e a descrição da co-existência de genótipos diferentes em Formosa, conclui-se que fica a evidência da existência de dois genotipos no Brasil uma vez que a amostra 56C é diferente da amostra de São Paulo e da 70C, geneticamente similar a maioria dos isolados do mundo, mesmo mantendo características clínicas e hematológicas clássicas da EMC.

[...] The product was sequenced and similarity analysis carried out showed identity with values ranging between 95.7% and 100%. The second step was to analyze the sequence of the gene encoding the gp19 and gp36 protein, which was performed using specific primers and 11 only encoding the gp19 and gp36 two were amplified. The coding sequences of gp19 and remained highly conserved gp36 showed similar characteristics of the different isolates (56C similar to the new genotypes of Taiwan strains and 70C genotype similar to Sao Paulo strain and other isolates of the world) After this study, the analysis of significance between the signs clinical and hematological findings were determined by means of contingency tables by the chi-square test and Fisher exact test. Of positive animals in Duque de Caxias, the clinical signs that were significant were apathy, anorexia and weight loss. Marica and Cachoeiras de Macacu significant clinical signs were dyspnea. Observing the main complaint related to the animal 56C and its clinical and hematological notices that are characteristic of a possible infection by E. canis which does not happen with the animal 70C. Considering together the different clinical and hematological characteristics of the two animals, the differences in the sequences of the gene encoding the protein gp36 and the description of the co-existence of different genotypes in Taiwan, it is concluded that the evidence is the existence of two genotypes in Brazil since the sample is different from the 56C sample of Sao Paulo and 70C, the most genetically similar isolates of the world, while maintaining clinical and hematological features of classical EMC.

Mitochondrial DNA analysis of Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) in the Southern Cone of South America.

A genetic analysis of partial sequences of the mitochondrial 16S and 12S rDNA genes of Rhipicephalus sanguineus sensu lato collected in the Southern Cone of South America was carried out. Also, sequences of ticks belonging to this taxon from Europe, Africa and other South American localities were included. TCS networks constructed with 16S rDNA sequences showed two clusters of haplotypes, namely, Southern lineage (ST) and Northern lineage (NT). Haplotypes representing the specimens coming from localities of Argentina, Uruguay and Chile were included in the ST lineage, while haplotypes from Brazil, Paraguay, Colombia, South Africa, Mozambique and from two localities of Northern Argentina were grouped in the NT lineage. The phylogenetic trees obtained with both 16S and 12S sequences showed two distinct clades, one containing R. sanguineus s.l from Argentina, Uruguay, Chile (ST lineage) and Western Europe (Italy and France), and a second clade including R. sanguineus s.l from Argentina, Paraguay, Brazil, Colombia (NT lineage), South Africa and Mozambique. The results herein reported revealed that the taxon R. sanguineus s.l is represented by two lineages in the Southern Cone of South America. According with the genetic comparative analysis, NT lineage and the ticks from Mozambique and South Africa represent a species that is not R. sanguineus s.s, while R. sanguineus s.l ticks from Western Europe and Southern South America (ST lineage) probably represent true R. sanguineus, because the type locality of R. sanguineus s.s is located in France. The taxonomic issue described for R. sanguineus s.l in the South America has epidemiological implications. Difference in the vectorial competence for Ehrlichia canis between the two lineages of R. sanguineus s.l was found in previous works. Further investigations are needed in order to verify a possible different vectorial competence for the other pathogens transmitted by these ticks.

Degenerative process and cell death in salivary glands of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged female exposed to the acaricide permethrin.

Ticks are ectoparasites of great medical and veterinary importance around the world and synthetic chemicals such as permethrin have been used for their control. This study provides a cytochemistry analysis of both degenerative and cell death processes in salivary glands of the brown dog tick Rhipicephalus sanguineus semi-engorged females exposed to 206, 1,031, and 2,062 ppm of permethrin. The results presented herein demonstrate that permethrin is a potent chemical acaricide that would act on the glandular tissue's morphophysiology in this tick species by eliciting severe changes in the acinus shape, intense vacuolation of the acinar cells' cytoplasm, marked glandular tissue disorganization, culminating in an advanced degenerative stage with consequent formation of many apoptotic bodies (cell death). In addition, permethrin induced major changes in the acinar cells' nucleus, such as a change both in its shape and size, chromatin marginalization, nuclear fragmentation, and appearance of picnotic nuclei, especially when the highest concentrations of the product were used. Thus, permethrin induced early degeneration of this tissue characterized by significant changes in the structure of acinar cells and production of enzymes related to the cell death process, in addition to interfering directly in the genetic material of these cells.

Genetic analysis of ticks belonging to the Rhipicephalus sanguineus group in Latin America.

Phylogenetic analyses based on mitochondrial 16S rDNA sequences were generated from Rhipicephalus sanguineus group specimens collected in 29 localities among 9 Latin-American countries, plus ticks collected in South Africa, Spain, and Italy. Sequences from Latin America generated six different haplotypes (A, B, C, D, E, and F). Phylogenetic analyses generated trees that segregated our tick sequences into two distinct clades: one is represented by haplotypes A-C, and South African R. sanguineus and Rhipicephalus turanicus ticks; the second clade is represented by haplotypes D-F, and European R. sanguineus and R. turanicus ticks. When haplotypes A-F are plotted in the Latin America map according to their geographical coordinates, it is clearly seen that haplotypes D-F are restricted to the southern portion of this continent, whereas haplotypes A-C are distributed in areas between northern Mexico and Brazil (except for the extreme south of this last country, where haplotype E was present). Hence, our phylogenetic analyses separated New World specimens of R. sanguineus into two distinct clades, one represented by tropical and subtropical populations (haplotypes A-C), here designated as the 'tropical' species. On the other hand, haplotypes D-F are here designated as the 'temperate' species because of their distribution in the southern portion of South America. Until recently, it was assumed that the R. sanguineus group was represented by a single species in the New World, namely R. sanguineus. While the present results coupled with recent studies support the presence of at least two species under the taxon R. sanguineus in the New World, they also show that even in the Old World, the taxon R. sanguineus might be represented by more than one species, since our phylogenetic analysis segregated European and South African R. sanguineus ticks into two distinct clades. The same can be applied for Spanish and South African R. turanicus.

The expression of genes coding for distinct types of glycine-rich proteins varies according to the biology of three metastriate ticks, Rhipicephalus (Boophilus) microplus, Rhipicephalus sanguineus and Amblyomma cajennense.

BACKGROUND: Ticks secrete a cement cone composed of many salivary proteins, some of which are rich in the amino acid glycine in order to attach to their hosts' skin. Glycine-rich proteins (GRPs) are a large family of heterogeneous proteins that have different functions and features; noteworthy are their adhesive and tensile characteristics. These properties may be essential for successful attachment of the metastriate ticks to the host and the prolonged feeding necessary for engorgement. In this work, we analyzed Expressed Sequence Tags (ESTs) similar to GRPs from cDNA libraries constructed from salivary glands of adult female ticks representing three hard, metastriate species in order to verify if their expression correlated with biological differences such as the numbers of hosts ticks feed on during their parasitic life cycle, whether one (monoxenous parasite) or two or more (heteroxenous parasite), and the anatomy of their mouthparts, whether short (Brevirostrata) or long (Longirostrata). These ticks were the monoxenous Brevirostrata tick, Rhipicephalus (Boophilus) microplus, a heteroxenous Brevirostrata tick, Rhipicephalus sanguineus, and a heteroxenous Longirostrata tick, Amblyomma cajennense. To further investigate this relationship, we conducted phylogenetic analyses using sequences of GRPs from these ticks as well as from other species of Brevirostrata and Longirostrata ticks. RESULTS: cDNA libraries from salivary glands of the monoxenous tick, R. microplus, contained more contigs of glycine-rich proteins than the two representatives of heteroxenous ticks, R. sanguineus and A. cajennense (33 versus, respectively, 16 and 11). Transcripts of ESTs encoding GRPs were significantly more numerous in the salivary glands of the two Brevirostrata species when compared to the number of transcripts in the Longirostrata tick. The salivary gland libraries from Brevirostrata ticks contained numerous contigs significantly similar to silks of true spiders (17 and 8 in, respectively, R. microplus and R. sanguineus), whereas the Longirostrata tick contained only 4 contigs. The phylogenetic analyses of GRPs from various species of ticks showed that distinct clades encoding proteins with different biochemical properties are represented among species according to their biology. CONCLUSIONS: We found that different species of ticks rely on different types and amounts of GRPs in order to attach and feed on their hosts. Metastriate ticks with short mouthparts express more transcripts of GRPs than a tick with long mouthparts and the tick that feeds on a single host during its life cycle contain a greater variety of these proteins than ticks that feed on several hosts.

Molecular dissimilarities of Rhipicephalus sanguineus (Acari: Ixodidae) in Brazil and its relation with samples throughout the world: is there a geographical pattern?

In this study the genetic variability of Rhipicephalus sanguineus within Brazil and its relation with ticks of the same group from different continents was evaluated. Mitochondrial 12S and 16S rDNA fragments of R. sanguineus from seven Brazilian States were sequenced and compared to GenBank sequences of R. sanguineus and R. turanicus ticks from Africa, Asia, Europe, South America and USA. Results indicate a relatively high intra-specific variability between Brazilian samples but also a global latitude linked distribution pattern of at least two major R. sanguineus groups; one group distributed from latitude 25 degrees N to 22 degrees S including R. sanguineus from Brazil, Taiwan and Thailand and R. turanicus from Zambia and Zimbabwe, and the other group found closer to the poles, roughly above 29 degrees N and below 30 degrees S with ticks from Argentina, Uruguay, France, Oklahoma (USA), Israel and Egypt.

[Mutagenic occurrence in teleoginae of Rhipicephalus sanguineus from intradomiciliary environment at Rio de Janeiro city]. / Malformação em teleógina de Rhipicephalus sanguineus recolhida em ambiente intradomiciliar, no Rio de Janeiro, RJ.

From material collected by into a residence house at Rio de Janeiro city, using an aspirator machine during four continues hours in all house, it was captured 1,284 Rhipicephalus sanguineus including 289 females; one of them showed a mutagenic alteration like an asymmetry of opistosome, and monstrosity like a two anus. The first register of this phenomenon in R. sanguineus is reported.