Population structure of the Atlantic seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) based on geometric morphometrics / Estructura de la población del camarón langostino del atlántico Xiphopenaeus kroyeri (Heller, 1862) basada en morfometría geométrica

SUMMARY: In 2004, Xiphopenaeus kroyeri, one of major species in commercial fisheries in Brazil was included in the list of brazilian overfished species and, in 2006, two cryptic species were identified in the Atlantic Ocean by molecular approaches: Xiphopenaeus sp. I and II. In 2019, Carvalho-Batista et al. described both Xiphopenaeus sp. I and Xiphopenaeus sp. II and these species were named X. kroyeri and X. dincao, respectively. This study aimed at performing morphometric analysis in order to identify potential fishing stocks of X. kroyeri sensu strictum along Brazilian coast. The results obtained separate Caravelas, Atafona and Balneário Camboriú from all the other populations studied and showed three groups: Ubatuba, Nova Almeida; Ubatuba, Cananéia; Ubatuba, Santos. These results indicate that the maritime limits practiced in closed seasons along Brazil are embracing the detected morphometric stock boundaries observed for Xiphopenaeus kroyeris.s.

RESUMEN: En 2004, Xiphopenaeus kroyeri, una de las principales especies de la pesca comercial en Brasil, fue incluida en la lista de especies brasileñas sobre explotadas y, en 2006, se identificaron dos especies crípticas en el Océano Atlántico mediante enfoques moleculares: Xiphopenaeus sp. I y II. En 2019, Carvalho-Batista et al. describieron tanto Xiphopenaeus sp. I y Xiphopenaeus sp. II y a estas especies denominaron X. kroyeri y X. dincao, respectivamente. Este estudio tuvo como objetivo realizar un análisis morfométrico con el fin de identificar posibles poblaciones de pesca de X. kroyeri sensu strictum a lo largo de la costa brasileña. Los resultados obtenidos en Caravelas, Atafona y Balneário Camboriú se separaron de todas las demás poblaciones estudiadas y mostraron tres grupos: Ubatuba, Nova Almeida; Ubatuba, Cananéia; Ubatuba, Santos. Estos resultados indican que los límites marítimos practicados en temporadas de veda a lo largo de Brasil están abarcando los límites de stock morfométricos observados para Xiphopenaeus kroyeris.s.

Infestation of peridomestic Attalea phalerata palms by Rhodnius stali, a vector of Trypanosoma cruzi in the Alto Beni, Bolivia.

OBJECTIVES: To determine (i) whether peridomestic Attalea phalerata palms in fragmented human-occupied areas of the Alto Beni, Bolivia, are infested by triatomines; (ii) the specific status of triatomines captured in the area; and (iii) the rate of natural Trypanosoma cruzi infection among those triatomines. METHODS: One hundred and twenty-five live-bait traps were used to sample 47 A. phalerata palms in three Alto Beni localities. Active search for vectors was also performed in 10 chicken coops and three rice storage units. Only Rhodnius specimens were found. As nymphs of closely related Rhodnius species are morphologically undistinguishable, and because of controversy in the literature regarding which Rhodnius species occur in Bolivia, collected insects were identified through molecular taxonomy. Phylogenetic analyses of DNA sequences obtained for a fragment of the mitochondrial cytochrome b gene and for the nuclear ITS-2 ribosomal region were used as molecular markers. Natural infection rates were determined using a pair of primers that PCR-amplify a 330-bp fragment of the parasite's kDNA. RESULTS: Twelve nymphs were captured in five A. phalerata palms (from two of the three localities studied), and an adult was collected from a chicken coop in Iniqua (and morphologically identified as Rhodnius stali). All nymphs (as well as the adult) were molecularly identified as R. stali based on the two molecular markers used. A single nymph was found to be infected with T. cruzi. CONCLUSIONS: Attalea phalerata palms represent an important sylvatic ecotope occupied by R. stali in the Alto Beni region of Bolivia, where there are signs of T. cruzi transmission to humans, despite the preliminary indication of low level of natural infection of the vectors.

New insights on the spread of Triatoma infestans from Bolivia--implications for Chagas disease emergence in the southern cone.

Triatoma infestans, now eliminated from most of South America by control campaigns, has been and still is the main Chagas disease vector due to its ability to colonize rural dwellings. The traditional hypothesis put forth to explain T. infestans adaptation to the synanthropic environment rests on the domestication of wild guinea pigs, one of its natural hosts, by Andean tribes about 5000 BC. Here we present two new hypotheses, based on organized human social activities. The first involves maize production, storage and distribution during the Inca period. Maize granaries could host wild rodent populations that would attract sylvatic T. infestans that were later dispersed during maize distribution. The second hypothesis is associated with the contemporary Urkupiña Virgin festival, near Cochabamba, where thousands of pilgrims gather for rituals in an area that is part of a sylvatic T. infestans focus, thus favoring the contact with the insects and leading to their passive dispersal.

Systematics of Mepraia (Hemiptera-Reduviidae): cytogenetic and molecular variation.

The haematophagous insects of the subfamily Triatominae (Hemiptera-Reduviidae) have great epidemiological importance as vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Mepraia was originally described as a monotypic genus comprised of Mepraia spinolai, distributed along coastal areas of northern Chile (from Region I to the Metropolitan Region). Recently, some M. spinolai populations have been ranked as a new species named Mepraia gajardoi. Several populations along the distribution range of the genus were sampled, and genetic differentiation was studied based upon the analysis of three molecular markers: cytogenetics (karyotype and chromosome behaviour during meiosis using the C-banding technique), mitochondrial DNA (a cytochrome oxidase I gene fragment), and nuclear ribosomal DNA (intergenic region including the two internal transcribed spacers ITS-1 and ITS-2 and the 5.8S rRNA gene). The data here presented indicate that populations within the Mepraia genus (excluding Region II specimens) can be divided into two separate lineages. One lineage is comprised of specimens from the northernmost Region I and represents M. gajardoi. The other includes samples from the southern III, IV and the Metropolitan Regions, and represents M. spinolai. Region II individuals deserve particular attention as their relationship to the two identified lineages is not clear-cut. While they appear to belong to M. spinolai based on cytogenetics and rDNA markers, COI results indicate a closer relationship to M. gajardoi. This disagreement can be due to mitochondrial DNA introgression or the retention of ancestral polymorphisms.

Comparative phylogeography of Trypanosoma rangeli and Rhodnius (Hemiptera: Reduviidae) supports a long coexistence of parasite lineages and their sympatric vectors.

To make reliable interpretations about evolutionary relationships between Trypanosoma rangeli lineages and their insect vectors (triatomine bugs of the genus Rhodnius) and, thus, about the determinant factors of lineage segregation within T. rangeli, we compared phylogenies of parasite isolates and vector species. Sixty-one T. rangeli isolates from invertebrate and vertebrate hosts were initially evaluated in terms of polymorphism of the spliced-leader gene (SL). Further analysis based on SL and SSUrRNA sequences from 33 selected isolates, representative of the overall phylogenetic diversity and geographical range of T. rangeli, supported four phylogenetic lineages within this species. By comparing the phylogeny of Rhodnius species with that inferred for T. rangeli isolates and through analysis of the geographical range of the isolates, we showed that there is a very significant overlap in the distribution of Rhodnius species and T. rangeli lineages. Congruence between phylogeographical analysis of both T. rangeli lineages and complexes of Rhodnius species are consistent with the hypothesis of a long coexistence of parasites and their vectors, with lineage divergence associated with sympatric species of Rhodnius apparently without association with particular vertebrate hosts. Separation of T. rangeli isolates from vectors of distinct complexes living in sympatry favours the absence of gene flow between the lineages and suggests evolution of T. rangeli lineages in independent transmission cycles, probably associated to specific Rhodnius spp. ecotopes. A polymerase chain reaction assay based on SL intergenic sequences was developed for simultaneous identification and lineage genotyping of T. rangeli in epidemiological surveys.

A multiplex PCR assay that separates Rhodnius prolixus from members of the Rhodnius robustus cryptic species complex (Hemiptera: Reduviidae).

Rhodnius prolixus is one of the most important primary vectors of human Chagas disease in Latin America. Its morphology is, however, identical to that of the members of the Rhodnius robustus cryptic species complex, which includes secondary vectors. The correct identification of these taxa with differential vector competence is, therefore, of great epidemiological relevance. We used the alignment of 26 mitochondrial cytochrome b haplotypes (663 bp) to select for PCR-amplifiable species-specific regions. We designed one forward primer on a region conserved across all haplotypes, and three reverse primers that anneal to species-specific regions and amplify fragments of different lengths for R. prolixus (285 bp) and for members of the two major R. robustus lineages: group I (349 bp) and groups II-IV (239 bp). These fragments were easily identifiable on regular 1.5% agarose gels. This multiplex PCR assay was successfully tested on 81 specimens from six Latin American countries, and used to determine the phylogeographic boundaries for each species. It is a simple, objective, and cost-effective assay. Its PCR-based nature makes it applicable to any insect developmental stage, as well as to dried specimens, and insect remains. It should be particularly useful in areas where representatives of these Rhodnius species occur in sympatry.

Molecular confirmation of the specific status of Anopheles halophylus (Diptera: Culicidae) and evidence of a new cryptic species within An. triannulatus in central Brazil.

Anopheles halophylus Silva-do-Nascimento & Lourenço-de-Oliveira was recently described using morphological and biological variants in specimens previously identified as Anopheles triannulatus (Neiva & Pinto). Because these two species occur in sympatry in central Brazil, we used allozymes to determine the extent of gene flow to confirm that they are different species. Of 11 allozyme loci analyzed, one (Mpi) was found to be diagnostic for An. halophylus and An. triannulatus, confirming their specific status. This locus revealed a second sibling species within An. triannulatus sensu lato. An. halophylus and the new undescribed species were confirmed using random amplified polymorphic DNA markers that showed moderate genetic divergence among these three sympatric and closely related taxa (D = 0.145-0.428). Moreover, this marker indicates that An. halophylus and the new species are more closely related to each other than either is to An. triannulatus.

Activation of ERK1/2 MAP kinases in familial amyloidotic polyneuropathy.

Familial amyloidotic polyneuropathy (FAP) is a neurodegenerative disorder characterized by the extracellular deposition of transthyretin (TTR), especially in the PNS. Given the invasiveness of nerve biopsy, salivary glands (SG) from FAP patients were used previously in microarray analysis; mitogen-activated protein (MAP) kinase phosphatase 1 (MKP-1) was down-regulated in FAP. Results were validated by RT-PCR and immunohistochemistry both in SG and in nerve biopsies of different stages of disease progression. MKP-3 was also down-regulated in FAP SG biopsies. Given the relationship between MKPs and MAPKs, the latter were investigated. Only extracellular signal-regulated kinases 1/2 (ERK1/2) displayed increased activation in FAP SG and nerves. ERK1/2 kinase (MEK1/2) activation was also up-regulated in FAP nerves. In addition, an FAP transgenic mouse model revealed increased ERK1/2 activation in peripheral nerve affected with TTR deposition when compared to control animals. Cultured rat Schwannoma cell line treatment with TTR aggregates stimulated ERK1/2 activation, which was partially mediated by the receptor for advanced glycation end-products (RAGE). Moreover, caspase-3 activation triggered by TTR aggregates was abrogated by U0126, a MEK1/2 inhibitor, indicating that ERK1/2 activation is essential for TTR aggregates-induced cytotoxicity. Taken together, these data suggest that abnormally sustained activation of ERK in FAP may represent an early signaling cascade leading to neurodegeneration.

Allozyme relationships among ten species of Rhodniini, showing paraphyly of Rhodnius including Psammolestes.

Genetic relationships among 10 species of bugs belonging to the tribe Rhodniini (Hemiptera: Reduviidae), including some important vectors of Chagas disease, were inferred from allozyme analysis of 12 enzyme loci (out of 21 enzyme systems examined), using agarose gel electrophoresis. These species formed two clusters: one comprising Rhodnius brethesi, R. ecuadoriensis, R. pallescens and R. pictipes; the other with Psammolestes tertius, Rhodnius domesticus and the Rhodnius prolixus group comprising R. nasutus, R. neglectus, R. prolixus and R. robustus. The resulting tree was [((R. ecuadoriensis, R. pallescens) R. brethesi) R. pictipes], [R. domesticus (P. tertius [(R. nasutus, R. neglectus) (R. prolixus, R. robustus)])]. Rhodnius nasutus and R. neglectus differed by only one locus, whereas no diagnostic loci were detected between R. prolixus and R. robustus (22 loci were analysed for these four species), despite considerable DNA sequence divergence between species in each of these pairs. Allozymes of the R. prolixus group showed greater similarity with Psammolestes tertius than with other Rhodnius spp., indicating that Rhodnius is paraphyletic and might include Psammolestes.

Molecular tools and triatomine systematics: a public health perspective.

Triatomines, or kissing bugs, are vectors of Chagas disease to humans. This disease is a substantial public health problem affecting up to 12 million people throughout the Americas, and its control relies mainly on the insecticide treatment of triatomine-infested houses within villages. In this article, Fernando Monteiro, Ananias Escalante and Ben Beard review how molecular markers have been used to clarify triatomine systematics, and give examples of how our understanding of triatomine population structure and accurate vector identification can be used to optimize vector control.

Studies on populations of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) in Brazil.

Studies were performed on five Brazilian populations of Lutzomyia longipalpis: Salvaterra (PA), São José do Ribamar (MA), Canindé (CE), Natal (RN) and Gruta da Lapinha, Lagoa Santa (MG). No morphological differences were observed that could distinguish between these populations. Homogeneity tests showed that the allopatric populations display a certain heterogeneity and that the sympatric populations, with different patterns of spots, are homogeneous. The Student-Newman-Keuls test, represented by Euler-Venn diagrams, showed a disjunction between the populations from the north/northeast and the one from Gruta da Lapinha. Genetic distances between the four populations (excluding the Canindé population) were within the range of intrapopulational differences. The Gruta da Lapinha population displayed a heterozygotic deficiency that could be a consequence of high levels of inbreeding due to cryptic habits of living in a small cave. These results do not favor the hypothesis of a L. longipalpis species complex in Brazil, and the species should be considered high polymorphic.

Phylogeny and molecular taxonomy of the Rhodniini derived from mitochondrial and nuclear DNA sequences.

Eleven species of Rhodnius and one of Psammolestes were compared by DNA sequence analysis of fragments of the mitochondrial large subunit ribosomal RNA (mtlsurRNA), the mitochondrial cytochrome b (mtCytb), and the D2 variable region of the 28S nuclear RNA (D2), totaling 1,429 base pairs. The inferred phylogeny, using Triatoma infestans as an outgroup, revealed two main clades within the Rhodniini--one, including the prolixus group of species (Rhodnius prolixus, Rhodnius robustus, Rhodnius neglectus, and Rhodnius nasutus) together with Rhodnius domesticus and Rhodnius neivai, and the other comprising two groups formed by Rhodnius pictipes plus Rhodnius brethesi, and Rhodnius ecuadoriensis plus Rhodnius pallescens. Psammolestes tertius appeared most closely related to the prolixus group. The analysis strongly supports the validity of R. robustus as a species distinct from others of the prolixus group, but suggests higher genetic structuring of R. robustus populations compared to the other species. Although R. robustus has been found naturally infected by Trypanosoma cruzi, the fact that it is apparently entirely sylvatic and unable to establish in homes suggests that it is of no great importance as a Chagas disease vector in humans.

Mitochondrial DNA sequence variation among triatomine vectors of Chagas' disease.

Kissing bugs or triatomines (Reduviidae: Triatominae) are vectors of the Chagas' disease agent Trypanosoma cruzi. There is a current need for more sensitive tools for use in discrimination of different bug populations and species, thus allowing a better understanding of these insects as it relates to disease transmission and control. In a preliminary analysis of the mitochondrial large subunit ribosomal RNA (mtlsurRNA) and cytochrome B (mtCytB) genes, we used DNA sequencing to study species identification and phylogeny. In both examined gene regions, about 46% of nucleotide positions exhibited polymorphism. The examined region of mtCytB appears to have evolved more rapidly than the examined region of mtlsurRNA. Phylogenetic analysis of both gene fragments in the examined species produced similar results that were generally consistent with the accepted taxonomy of the subfamily. The two major tribes, Rhodniini and Triatomini, were supported, along with additional clades that corresponded to accepted species complexes within the Rhodnius and Triatoma genera. The one chief exception was that Psammolestes coreodes sorted into the Rhodnius prolixus-robustus-neglectus clade, with bootsrap values of 99% and 81%, respectively, for the mtlsurRNA and mtCytB fragments. All of the individual species examined could be distinguished at both genetic loci.

Mitochondrial DNA variation of Triatoma infestans populations and its implication on the specific status of T. melanosoma.

DNA sequence comparison of 412 base-pairs fragments of the mitochondrial cytochrome B gene was used to infer the genetic structure of nine geographical Triatoma infestans populations and their phylogenetic relationship with T. melanosoma and T. brasiliensis. T. infestans and T. melanosoma were compared by morphometry, allozyme and cytogenetic analyses, as well as subjected to reciprocal crosses, in order to clarify the taxonomic status of the latter. No differences were found to distinguish the two species and the crosses between them yielded progeny. T. infestans populations presented four haplotypes that could be separated in two clusters: one formed by the samples from Bolivia (Andes and Chaco) and the other formed by samples from Argentina and Brazil. Silvatic and domestic T. infestans populations from Bolivia (Andes) were genetically identical.

Preliminary evaluation of the genetic relatedness of three species of the subgenus Dendromyia Theobald and other species of the genus Wyeomyia Theobald (Diptera: Culicidae).

An eletrophoretic analysis of three species of the subgenus Dendromyia (Wyeomyia luteoventralis, Wy. ypsipola and Wy. testei) and three species belonging to different groups in the genus Wyeomyia (Wy. negrensis, Wy. mystes and Wy. confusa) was performed. Eight enzyme loci were analyzed. High values of genetic identify were detected among the species of the subgenus Dendromyia: Wy. luteoventralis, Wy. ypsipola and Wy. testei (mean value 0.63). On the other hand low values of genetic identify were observed among Wy. negrensis, Wy. mystes and Wy. confusa (mean value 0.23), suggesting that they belong, at least, to distinct subgenera within the Genus Wyeomyia. The UPGMA phenogram revealed the grouping of the Dendromyia species, while the others clustered at lower identity levels.