Phylogeographic Pattern and Extensive Mitochondrial DNA Divergence Disclose a Species Complex within the Chagas Disease Vector Triatoma dimidiata

Background

Triatoma dimidiata is among the main vectors of Chagas disease in Latin America. However, and despite important advances, there is no consensus about the taxonomic status of phenotypically divergent T. dimidiata populations, which in most recent papers are regarded as subspecies.

Methodology and Findings

A total of 126 cyt b sequences (621 bp long) were produced for specimens from across the species range. Forty-seven selected specimens representing the main cyt b clades observed (after a preliminary phylogenetic analysis) were also sequenced for an ND4 fragment (554 bp long) and concatenated with their respective cyt b sequences to produce a combined data set totalling 1175 bp/individual. Bayesian and Maximum-Likelihood phylogenetic analyses of both data sets (cyt b, and cyt b+ND4) disclosed four strongly divergent (all pairwise Kimura 2-parameter distances >0.08), monophyletic groups: Group I occurs from Southern Mexico through Central America into Colombia, with Ecuadorian specimens resembling Nicaraguan material; Group II includes samples from Western-Southwestern Mexico; Group III comprises specimens from the Yucatán peninsula; and Group IV consists of sylvatic samples from Belize. The closely-related, yet formally recognized species T. hegneri from the island of Cozumel falls within the divergence range of the T. dimidiata populations studied.

Conclusions

We propose that Groups I–IV, as well as T. hegneri, should be regarded as separate species. In the Petén of Guatemala, representatives of Groups I, II, and III occur in sympatry; the absence of haplotypes with intermediate genetic distances, as shown by multimodal mismatch distribution plots, clearly indicates that reproductive barriers actively promote within-group cohesion. Some sylvatic specimens from Belize belong to a different species – likely the basal lineage of the T. dimidiata complex, originated ∼8.25 Mya. The evidence presented here strongly supports the proposition that T. dimidiata is a complex of five cryptic species (Groups I–IV plus T. hegneri) that play different roles as vectors of Chagas disease in the region.     

Incorporación de la ecografía y la punción de tiroides a la actividad de endocrinología en una consulta de alta resolución

IntroductionFine-needle aspiration biopsy (FNAB) is considered the reference diagnostic procedure for thyroid nodules.Materials and methodsRoutine performance of thyroid ultrasound and ultrasound-guided FNAB by endocrinologists allows a more efficient approach in the setting of a high-resolution practice, thus reducing costs and the time elapsed until diagnosis.ResultsWe present our initial results of this procedure 2 years after its introduction, with a total of 286 biopsies performed. After a progressive learning curve over time and according to the endocrinologists’ previous experience, 72.72% samples were considered satisfactory for diagnosis. Greater difficulty was observed in obtaining optimal cytological specimens in smaller nodules. In conclusion, we have successfully incorporated thyroid ultrasound and ultrasound-guided FNAB into routine endocrine practice.ConclusionRoutine performance of thyroid ultrasound in endocrine practice will considerably aid the management of nodular thyroid disease.     

Prevalence of viable Toxoplasma gondii in beef, chicken, and pork from retail meat stores in the United States: risk assessment to consumers

The prevalence of viable Toxoplasma gondii was determined in 6,282 samples (2,094 each of beef, chicken, and pork) obtained from 698 retail meat stores from 28 major geographic areas of the United States. Each sample consisted of a minimum of 1 kg of meat purchased from the retail meat case. To detect viable T. gondii, meat samples were fed to T. gondii-free cats and feces of cats were examined for oocyst shedding. Initially, 100 g of meat from 6 individual samples of a given species were pooled (total, 600 g), fed to a cat over a period of 3 days, and feces were examined for oocysts for 14 days; the remaining meat samples were stored at 4 C for 14 days (until results of the initial cat fecal examination were known). When a cat fed pooled samples had shed oocysts, 6 individual meat samples from each pool were bioassayed for T. gondii in cats and mice. Toxoplasma gondii isolates were then genetically characterized using the SAG2 locus and 5 hypervariable microsatellite loci. In all, 7 cats fed pooled pork samples shed oocysts. Toxoplasma gondii oocysts were detected microscopically in the feces of 2 of the cats; 1 isolate was Type II and the second was Type III. Analyzed individually, T. gondii was detected by bioassay in 3 of the 12 associated samples with genetic data indicating T. gondii isolates present in 2. The remaining 5 pooled pork samples had so few oocysts that they were not initially detected by microscopic examination, but rather by mouse bioassay of cat feces. Two were Type I, 1 was Type II, and 2 were Type III. None of the cats fed chicken or beef samples shed oocysts. Overall, the prevalence of viable T. gondii in retail meat was very low. Nevertheless, consumers, especially pregnant women, should be aware that they can acquire T. gondii infection from ingestion of undercooked meat, and in particular, pork. Cooking meat to an internal temperature of 66 C kills T. gondii.     

Extracellular adenine nucleotides inhibit the release of major monocyte recruiters by human monocyte-derived dendritic cells

Extracellular ATP is known to affect the maturation of monocyte-derived dendritic cells mainly by regulation of cytokines and costimulatory molecules. The present study describes the inhibition of MCP-1 (CCL2) and MIP-1alpha (CCL3) release by human monocyte-derived dendritic cells in response to adenine nucleotides. Our pharmacological data support the involvement of P2Y11 and P2Y1 purinergic receptors in the downregulation of these major monocyte recruiters. Migration assays have demonstrated that supernatants of dendritic cells treated with adenine nucleotides or anti-MCP-1/MIP-1alpha blocking antibodies display a strongly reduced capacity to attract monocytes and immature dendritic cells.     

Seasonal variations in active dispersal of natural populations of Triatoma infestans in rural north-western Argentina

The flight dispersal of Triatoma infestans Klug (Hemiptera: Reduviidae) is one of the main mechanisms determining community re-infestation after control interventions. An empirical model of flight initiation coupled with data from a longitudinal study predicted that the flight dispersal of T. infestans would peak in summer. To test this prediction, longitudinal light trap collections were conducted during 3-8 nights in March (late summer), July (winter) and November (spring) 2003, and in March 2004 in a rural community in north-west Argentina. Following each light-trapping collection date, all peridomestic sites around light traps were inspected to assess the relative abundance and nutritional status of T. infestans at each site. A total of 21 adult and five nymph T. infestans, six Triatoma guasayana Wygodzinsky & Abalos, and nine Triatoma garciabesi Carcavallo et al. were collected in 96 light-trapping nights, whereas 696 T. infestans were collected from the peridomestic sites that surrounded the light traps. The arrival of T. infestans in the light traps occurred in 64% of catch stations and peaked in the summer surveys (10-14 bugs) compared with spring and winter surveys. When winds were < 5 km/h, the arrival of adult T. infestans at the light traps was significantly associated with maximum temperature and relative humidity. This is the first field report of seasonal variations in the flight dispersal activity of T. infestans.     

Phylogenetic and phenotypic relationships among Triatoma carcavalloi (Hemiptera: Reduviidae: Triatominae) and related species collected in domiciles in Rio Grande do Sul State,Brazil

Triatoma carcavalloi is considered a rare Chagas disease vector often collected inside domiciles in Rio Grande do Sul State. In this Brazilian state, T. carcavalloi has been collected in the same ecotope (rock piles) with two other species (T. rubrovaria and T. circummaculata), with which it also shares morphological characteristics. Previous morphological studies placed T. carcavalloi in the same species complex (“infestans complex”) and subcomplex (“rubrovaria subcomplex”) as T. rubrovaria, whereas T. circummaculata was placed in the “circummaculata complex.” The phylogeny of a group composed of 16 species of triatomines was revaluated with the inclusion of T. carcavalloi by Bayesian analysis using mtDNA sequences of subunits 12S and 16S of the ribosomal RNA, and the cytochrome oxidase I (COI) genes. The phenotypic relationship among T. carcavalloi and related triatomines was also inferred from morphometrics. Phylogenetic results indicate that T. carcavalloi is a sister species of T. rubrovaria, and both were recovered as closely related to T. circummaculata. Morphometric studies confirmed the closeness among T. carcavalloi, T. rubrovaria, and T. circummaculata, prompting the placement of the latter species in the “infestans complex” and “rubrovaria subcomplex.”     

Responsiveness of human retinoblastoma and neuroblastoma models to a non-calcemic 19-nor Vitamin D analog

OBJECTIVES: To investigate the effectiveness of 2-methylene-19-nor-(20S)-1alpha-hydroxybishomopregnacalciferol (2MbisP) in inhibiting the growth of retinoblastoma (RB) and neuroblastoma (NB). METHODS: For the RB study, the xenograft athymic mouse/human retinoblastoma cell (Y-79) model and the transgenic beta-luteinizing hormone-large T antigen (LHbeta-Tag) mice were systemically treated with 2MbisP or vehicle for 5 weeks. For the NB study, the xenograft athymic mouse/human neuroblastoma cell (SK-N-AS) model was treated with 2MbisP or vehicle for 5 weeks. Tumor size and toxicity were assessed. RESULTS: In the xenograft models of RB and NB, 2MbisP caused statistically significant inhibition of tumor growth. Tumor growth inhibition was also observed in the transgenic RB mice, but did not achieve statistical significance. In all the groups, no biologically significant toxic effects were observed using the following variables: serum calcium levels, degree of kidney calcification, changes in body weight or survival. CONCLUSIONS: In athymic mice, 2MbisP was effective in inhibiting RB and NB growth compared with controls. A lesser effect was seen in the transgenic RB model. 2MbisP did not cause hypercalcemia or a significant increase in mortality. CLINICAL RELEVANCE: 2MbisP should be considered for use in clinical trials of RB and NB.     

Extracellular nucleotides regulate CCL20 release from human primary airway epithelial cells, monocytes and monocyte-derived dendritic cells

Extracellular nucleotides regulate ion transport and mucociliary clearance in human airway epithelial cells (HAECs) via the activation of P2 receptors, especially P2Y(2). Therefore, P2Y(2) receptor agonists represent potential pharmacotherapeutic agents to treat cystic fibrosis (CF). Nucleotides also modulate inflammatory properties of immune cells like dendritic cells (DCs), which play an important role in mucosal immunity. Using DNA-microarray experiments, quantitative RT-PCR and cytokine measurements, we show here that UTP up-regulated approximately 2- to 3-fold the antimicrobial chemokine CCL20 expression and release in primary HAECs cultured on permeable supports at an air-liquid interface (ALI). Both P2Y(2) (ATPgammaS, UTP, INS365) and P2Y(6) (UDP, INS48823) agonists increased CCL20 release. UTP-induced CCL20 release was insensitive to NF-kappaB pathway inhibitors but sensitive to inhibitors of ERK1/2 and p38/MAPK pathways. Furthermore, UTP had no effect on interleukin-(IL)-8 release and reduced the release of both CCL20 and IL-8 induced by TNF-alpha and LPS. Accordingly, UTP reduced the capacity of basolateral supernatants of HAECs treated with TNF-alpha or LPS to induce the chemoattraction of both CD4(+) T lymphocytes and neutrophils. In addition, we show that, in monocyte-derived DCs, ATPgammaS, and UDP but not UTP/INS365-stimulated CCL20 release. Likewise, UDP but not ATPgammaS was also able to increase CCL20 release from monocytes. Pharmacological experiments suggested an involvement of P2Y(11) or P2Y(6) receptors through NF-kappaB, ERK1/2, and p38/MAPK pathways. Altogether, our data demonstrate that nucleotides may modulate chemokine release and leukocyte recruitment in inflamed airways by acting on both epithelial and immune cells. Our results could be relevant for further clinical investigations in CF.