Derris (Lonchocarpus) urucu (Leguminosae) Extract Modifies the Peritrophic Matrix Structure of Aedes aegypti (Diptera:Culicidae)

Aqueous suspension of ethanol extracts of Derris (Lonchocarpus) urucu (Leguminosae), collected in the state of Amazonas, Brazil, were tested for larvicidal activity against the mosquito Aedes aegypti (Diptera:Culicidae). The aim of this study was to observe the alterations of peritrophic matrix in Ae. aegypti larvae treated with an aqueous suspension of D. urucu extract. Different concentrations of D. urucu root extract were tested against fourth instar larvae. One hundred percent mortality was observed at 150 µg/ml (LC50 17.6 µg/ml) 24 h following treatment. In response to D. urucu feeding, larvae excreted a large amount of amorphous feces, while control larvae did not produce feces during the assay period. Ultrastructural studies showed that larvae fed with 150 µg/ml of D. urucu extract for 4 h have an imperfect peritrophic matrix and extensive damage of the midgut epithelium. Data indicate a protective role for the peritrophic matrix. The structural modification of the peritrophic matrix is intrinsically associated with larval mortality.

Cutting edge: influence of the TCR V beta domain on the avidity of CD1d:alpha-galactosylceramide binding by invariant V alpha 14 NKT cells.

CD1d tetramers loaded with alpha-galactosylceramide (alpha-GalCer) bind selectively to mouse invariant Valpha14 (Valpha14i) NKT cells and their human counterparts. Whereas tetramer binding strictly depends on the expression of a Valpha14-Jalpha18 chain in murine NKT cells, the associated beta-chain (typically expressing Vbeta8.2 or Vbeta7) appears not to influence tetramer binding. In this study, we describe novel alpha-GalCer-loaded mouse and human CD1d-IgG1 dimers, which revealed an unexpected influence of the TCR-beta chain on the avidity of CD1d:alpha-GalCer binding. A subset of Valpha14i NKT cells clearly discriminated alpha-GalCer bound to mouse or human CD1d on the basis of avidity differences conferred by the Vbeta domain of the TCR-beta chain, with Vbeta8.2 conferring higher avidity binding than Vbeta7.

Intergenic and external transcribed spacers of ribosomal RNA genes in lizard-infecting Leishmania: molecular structure and phylogenetic relationship to mammal-infecting Leishmania in the subgenus Leishmania (Leishmania)

To establish the relationships of the lizard- and mammal-infecting Leishmania, we characterized the intergenic spacer region of ribosomal RNA genes from L. tarentolae and L. hoogstraali. The organization of these regions is similar to those of other eukaryotes. The intergenic spacer region was approximately 4 kb in L. tarentolae and 5.5 kb in L. hoogstraali. The size difference was due to a greater number of 63-bp repetitive elements in the latter species. This region also contained another element, repeated twice, that had an inverted octanucleotide with the potential to form a stem-loop structure that could be involved in transcription termination or processing events. The ribosomal RNA gene localization showed a distinct pattern with one chromosomal band (2.2 Mb) for L. tarentolae and two (1.5 and 1.3 Mb) for L. hoogstraali. The study also showed sequence differences in the external transcribed region that could be used to distinguish lizard Leishmania from the mammalian Leishmania. The intergenic spacer region structure features found among Leishmania species indicated that lizard and mammalian Leishmania are closely related and support the inclusion of lizard-infecting species into the subgenus Sauroleishmania proposed by Saf'janova in 1982.

Host characteristics do not affect community structure of ectoparasites on the fishing bat Noctilio leporinus (L., 1758) (Mammalia: Chiroptera)

Patterns of parasite abundance and prevalence are thought to be influenced by several host characteristics such as size, sex, developmental stage, and seasonality. We examined two obligatory ectoparasites of the bat Noctilio leporinus (L.) (Chiroptera, Noctilionidae) to test whether prevalence and abundance of Noctiliostrebla aitkeni Wenzel and Paradyschiria fusca Speiser (Diptera, Streblidae) are influenced by the host characteristics. During this survey, 2110 flies were collected. The total abundance was 1150 N. aitkeni and 950 P. fusca. The prevalence of both species was shown to be superior to 75% and neither host size, sex, reproductive stage nor season influenced significantly the variation of the observed values. N. aitkeni were more abundant than P. fusca in all seasons except winter. Both flies showed a significant seasonal variation in terms of abundance but host biological characteristics (host size, sex, and reproductive stage) did not play a significant role as structuring factors of the batflies component community.

Trypanosoma cruzi: genetic structure of populations and relevance of genetic variability to the pathogenesis of chagas disease

Chagas disease, caused by the protozoan Trypanosoma cruzi, has a variable clinical course, ranging from symptomless infection to severe chronic disease with cardiovascular or gastrointestinal involvement or, occasionally, overwhelming acute episodes. The factors influencing this clinical variability have not been elucidated, but it is likely that the genetic variability of both the host and the parasite are of importance. In this work we review the the genetic structure of T. cruzi populations and analyze the importance of genetic variation of the parasite in the pathogenesis of the disease under the light of the histotropic-clonal model.

Genetic structure of Triatoma venosa (Hemiptera: Reduviidae): molecular and morphometric evidence

Triatoma venosa presents a restricted geographical distribution in America and is considered as a secondary vector of Chagas disease in Colombia and Ecuador. A total of 120 adult insects were collected in domestic and peridomestic habitats in an endemic area of the department of Boyacá, Colombia, in order to determine their genetic structure through morphometric and molecular techniques. The head and wings of each specimen were used for the analyses of size, shape, and sexual dimorphism. A significant sexual dimorphism was found, although no differences in size among the studied groups were detected. Differences were found in the analyzed structures except for male heads. DNA was extracted from the legs in order to carry out the internal transcriber space-2 (ITS-2) amplification and the randon amplified polymorphic DNA (RAPD) analyses. Length polymorphisms were not detected in the ITS-2. Fst and Nm values were estimated (0.047 and 3.4, respectively). The high genetic flow found among the insects captured in the domicile and peridomiciliary environment does not permit a genetic differentiation, thus establishing the peridomicile as an important place for epidemiological surveillance.

A new Eimeria (Apicomplexa: Eimeriidae), possessing mitra-shaped oocysts, from the Neotropical chelid turtle Batrachemys heliostemma (Testudines: Chelidae), and its comparison with Eimeria mitraria (Laveran & Mesnil 1902)

Eimeria jirkamoraveci sp. n. is described from faeces of two specimens of the toad-headed, side-necked turtle Batrachemys heliostemma collected at Iquitos in Peru. Oocysts are ovoid to almost spherical, 10.6 (8-12) × 8.9 (7-10) mum, without micropyle, polar granule and oocyst residuum. One conically stretched end and three blunt conical tubercles at the opposite end of oocyst give it mitra-like appearance. Sporocysts are elongated, ellipsoidal, 7.2 (6-8) × 4.1 (4-4.5) mum, with a small, knob-like Stieda body and sporocyst residuum composed of fine granules. To avoid possible conspecificity, the described new species is thoroughly compared with the most similar coccidium, E. mitraria, collected from its type host, Chinemys reevesii.

The amphioxus genome and the evolution of the chordate karyotype.

Lancelets ('amphioxus') are the modern survivors of an ancient chordate lineage, with a fossil record dating back to the Cambrian period. Here we describe the structure and gene content of the highly polymorphic approximately 520-megabase genome of the Florida lancelet Branchiostoma floridae, and analyse it in the context of chordate evolution. Whole-genome comparisons illuminate the murky relationships among the three chordate groups (tunicates, lancelets and vertebrates), and allow not only reconstruction of the gene complement of the last common chordate ancestor but also partial reconstruction of its genomic organization, as well as a description of two genome-wide duplications and subsequent reorganizations in the vertebrate lineage. These genome-scale events shaped the vertebrate genome and provided additional genetic variation for exploitation during vertebrate evolution.

Population genetic structure of the dengue mosquito Aedes aegypti in Venezuela

The mosquito Aedes aegypti is the main vector of dengue in Venezuela. The genetic structure of this vector was investigated in 24 samples collected from eight geographic regions separated by up to 1160 km. We examined the distribution of a 359-basepair region of the NADH dehydrogenase subunit 4 mitochondrial gene among 1144 Ae. aegypti from eight collections. This gene was amplified by the polymerase chain reaction and tested for variation using single strand conformation polymorphism analysis. Seven haplotypes were detected throughout Venezuela and these were sorted into two clades. Significant differentiation was detected among collections and these were genetically isolated by distance.

Symbolic trephinations and population structure

The sample examined consists of 19 skulls with symbolic trephinations and 86 skulls without trepanations dated from the X century. Skulls were all excavated in the Great Hungarian Plain in the Carpathian Basin, which was occupied by the Hungarian conquerors at the end of the IX century. The variations of 12 cranial dimensions of the trephined skulls were investigated and compared to the skulls without trepanations after performing a discriminant analysis. The classification results evince that the variability of non-trephined skulls shows a more homogeneous and a more characteristic picture of their own group than the trephined samples, which corresponds to the notion, formed by archaeological evidence and written historical sources, of a both ethnically and socially differing population of the Hungarian conquerors. According to historical research, a part of the population was of Finno-Ugric origin, while the military leading layer of society can be brought into connection with Turkic ethnic groups. All the same, individuals dug up with rich grave furniture and supposed to belong to this upper stratum of society are primarily characterized by the custom of symbolic trephination, and, as our results demonstrate, craniologically they seem to be more heterogeneous.

In vivo study comparing an X-shaped polymethylmethacrylate and a cylindrical collagen implant for deep sclerectomy.

Background:  Study in vivo characteristics of a polymethylmethacrylate (PMMA) implant compared to the standard cylindrical collagen implant for deep sclerectomy (DS). Design:  Six-month comparative study. Samples:  Twenty eyes of ten rabbits. Methods:  Eyes were randomized to have DS with PMMA implant in one eye and collagen implant in the opposite eye. The growth of the new subconjunctival drainage vessels was assessed by combined fluorescein and indocyanin green anterior segment angiography; intrascleral and subconjunctival blebs were imaged by ultrasound biomicroscopy (UBM). At six months, outflow facility (C) was measured by anterior chamber perfusion and portions of one side of the DS were compared to portions on the 180° opposite side and native sclera on histology. Results:  The mean IOP preoperatively and at one, four, twelve, and twenty-four weeks was comparable in both groups (P > 0.1). UBM showed a statistically insignificant quicker regression of the subconjunctival bleb as well as a durable intrascleral lake in the PMMA group (P > 0.05). New drainage vessels were initially observed one month after surgery; they were more numerous in the PMMA group on angiographic and histological findings at 6 months (P < 0.05). The mean C increased significantly after surgery compared to preoperative values (P < 0.05) and no difference was observed between the implants (0.24 ± 0.06 µl/min/mmHg [PMMA] and 0.23 ± 0.07 µl/min/mmHg [collagen implant]) (P = 0.39). Conclusions:  Deep sclerectomy performed with PMMA or collagen implants showed similar IOP lowering effects, outflow facility increase, and degree of inflammatory reaction.

Population genetic structure of the major malaria vector Anopheles darlingi (Diptera: Culicidae) from the Brazilian Amazon, using microsatellite markers

The population genetic structure of Anopheles darlingi, the major human malaria vector in the Neotropics, was examined using seven microsatellite loci from nine localities in central and western Amazonian Brazil. High levels of genetic variability were detected (5-25 alleles per locus; H E = 0.519-0.949). There was deviation from Hardy-Weinberg Equilibrium for 59.79% of the tests due to heterozygote deficits, while the analysis of linkage disequilibrium was significant for only two of 189 (1.05%) tests, most likely caused by null alleles. Genetic differentiation (F ST = 0.001-0.095; Nm = 4.7-363.8) indicates that gene flow is extensive among locations < 152 km apart (with two exceptions) and reduced, but not absent, at a larger geographic scale. Genetic and geographic distances were significantly correlated (R² = 0.893, P < 0.0002), supporting the isolation by distance (IBD) model. The overall estimate of Ne was 202.4 individuals under the linkage disequilibrium model, and 8 under the heterozygote excess model. Analysis of molecular variance showed that nearly all variation (~ 94%) was within sample locations. The UPGMA phenogram clustered the samples geographically, with one branch including 5/6 of the state of Amazonas localities and the other branch the Acre, Rondônia, and remaining Amazonas localities. Taken together, these data suggest little genetic structure for An. darlingi from central and western Amazonian Brazil. These findings also imply that the IBD model explains nearly all of the differentiation detected. In practical terms, populations of An. darlingi at distances < 152 km should respond similarly to vector control measures, because of high gene flow.

A study of the scutellum in eight Chagas disease vector species from genus Triatoma (Hemiptera, Reduviidae) using optical and scanning electron microscopy

The aim of this study was to analyze the external morphology of the scutellum through optical microscopy and scanning electron microscopy (SEM) in male specimens of Triatoma costalimai, T. delpontei, T. eratyrusiformis, T. matogrossensis, T. infestans melanosoma, T. sherlocki, T. tibiamaculata, and T. vandae. A total of 30 photographs of the scutellum were made. Magnification varied from 50X to 750X. Regarding depth and forms of the central depression, the heart-shaped form was predominant, with some exceptions, so that this shape appears to be a common characteristic for species of genus Triatoma Laporte, 1832. In T. eratyrusiformis, a kind of sensillum with important taxonomic value was observed. The different sizes and shapes of the designs found on the posterior process of the scutellum were also of important taxonomic interest. The study of the scutellum based on SEM showed valuable characteristics, allowing the use of this structure to aid the diagnosis of triatomine species. Thus, more specimens in subsequent studies and analyses of morphometric parameters should contribute to agreement on phylogenetic aspects in this genus. A Key to eight species of Triatoma based on male scutellar morphology is presented.

Population structure of the malaria vector Anopheles darlingi in Rondônia, Brazilian Amazon, based on mitochondrial DNA

Anopheles darlingi is the most important Brazilian malaria vector, with a widespread distribution in the Amazon forest. Effective strategies for vector control could be better developed through knowledge of its genetic structure and gene flow among populations, to assess the vector diversity and competence in transmitting Plasmodium. The aim of this study was to assess the genetic diversity of An. darlingi collected at four locations in Porto Velho, by sequencing a fragment of the ND4 mitochondrial gene. From 218 individual mosquitoes, we obtained 20 different haplotypes with a diversity index of 0.756, equivalent to that found in other neotropical anophelines. The analysis did not demonstrate significant population structure. However, haplotype diversity within some populations seems to be over-represented, suggesting the presence of sub-populations, but the presence of highly represented haplotypes complicates this analysis. There was no clear correlation among genetic and geographical distance and there were differences in relation to seasonality, which is important for malarial epidemiology.

Anti-leishmanial and structure-activity relationship of ring substituted 3-phenyl-1-(1,4-di-N-oxide quinoxalin-2-yl)-2-propen-1-one derivatives

A series of ring substituted 3-phenyl-1-(1,4-di-N-oxide quinoxalin-2-yl)-2-propen-1-one derivatives were synthesized and tested for in vitro leishmanicidal activity against amastigotes of Leishmania amazonensis in axenical cultures and murine infected macrophages. Structure-activity relationships demonstrated the importance of a radical methoxy at position R3', R4' and R5'. (2E)-3-(3,4,5-trimethoxy-phenyl)-1-(3,6,7-trimethyl-1,4-dioxy-quinoxalin-2-yl)-propenone was the most active. Cytotoxicity on macrophages revealed that this product was almost six times more active than toxic.