Anopheles darlingi polytene chromosomes: revised maps including newly described inversions and evidence for population structure in Manaus

Salivary gland polytene chromosomes of 4th instar Anopheles darlingi Root were examined from multiple locations in the Brazilian Amazon. Minor modifications were made to existing polytene photomaps. These included changes to the breakpoint positions of several previously described paracentric inversions and descriptions of four new paracentric inversions, two on the right arm of chromosome 3 and two on the left arm of chromosome 3 that were found in multiple locations. A total of 18 inversions on the X (n = 1) chromosome, chromosome 2 (n = 7) and 3 (n = 11) were scored for 83 individuals from Manaus, Macapá and Porto Velho municipalities. The frequency of 2Ra inversion karyotypes in Manaus shows significant deficiency of heterozygotes (p < 0.0009). No significant linkage disequilibrium was found between inversions on chromosome 2 and 3. We hypothesize that at least two sympatric subpopulations exist within the An. darlingi population at Manaus based on inversion frequencies.

An overview of malaria transmission from the perspective of Amazon Anopheles vectors

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Ano- pheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.

Occurrence of apocrine secretion in the larval gut epithelial cells of Aedes aegypti L., Anopheles albitarsis Lynch-Arribálzaga and Culex quinquefasciatus say (Diptera: Culicidae): a defense strategy against infection by Bacillus sphaericus Neide? / Ocorrência de secreção apócrina nas células epiteliais do intestino de larvas de Aedes aegypti L., Anopheles albitarsis Lynch-Arribálzaga e Culex quinquefasciatus say (Diptera: Culicidae): um mecanismo de defesa contra infecção causada por Bacillus sphaericus Neide?

Cell hypertrophy was the first reaction of the gut epithelial cells of Aedes aegypti (L.), Anopheles albitarsis (Lynch-Arribálzaga) and Culex quinquefasciatus (Say) to the toxins of strains 2362 and S1116 of Bacillus sphaericus, as cells had an increase of intracellular secretory activity. Soon after the cell hypertrophy developed, vesicles were formed at the cell apical portion, which detached with the plasma membrane, characterizing a type of apocrine secretion like. The first pathway of contamination of the mosquito larvae by these bacteria is through the gut, by feeding. Depending on the species of Culicidae and on the bacterial strain used, the hypertrophy of the gut epithelium occurred between 5 and 15 min after exposure to the contaminated environment. The second aspect observed after hypertrophy was the increase in apocrine secretion. The basophilic vesicles that detached from the cells remained between the peritrophic membrane and the gut lumen, such vesicles were filled with material of unknown nature. The gut posterior region showed secretory activity in both control and treated larvae, being much more intense in bacteria-exposed larvae. There were remarkable differences in the epithelial cell reaction according to the toxins of the two bacterial strains, but C.quinquefasciatus was the most susceptible. Differences in the gut cell reactions to the toxins produced by the two bacterial strains are discussed.

Observou-se hipertrofia das células do epitélio intestinal de Aedes aegypti (L.), Anopheles albitarsis (Lynch-Arribálzaga) e Culex quinquefasciatus (Say) devido ao aumento da atividade secretora intracelular como primeira reação às toxinas das linhagens 2362 e S1116 de Bacillus sphaericus (Neide). Após a hipertrofia epitelial, formaram-se vesículas na porção apical das células, as quais eram compostas de fragmentos de membrana plasmática contendo material de natureza desconhecida em seu interior, caracterizando um tipo de secreção apócrina. A via de contaminação das larvas dos mosquitos por essas bactérias é pelo intestino, através da alimentação. Dependendo da espécie de Culicidade e da linhagem bacteriana utilizada, a hipertrofia do epitélio ocorreu entre 5 a 15 min após a exposição das larvas ao meio contaminado. O segundo aspecto observado no processo de contaminação foi o aumento da atividade de secreção apócrina. As vesículas basófilas que se desprendiam das células permaneciam entre a membrana peritrófica e o lúmen intestinal. Observou-se atividade secretora tanto no grupo controle como no experimental, porém muito mais intensa no grupo experimental. Os Culicidae estudados apresentaram diferenças marcantes nas respostas às toxinas das bactérias utilizadas, sendo C. quinquefasciatus a espécie mais suscetível. As diferenças de reações das células em relação às toxinas produzidas pelas duas linhagens bacterianas são discutidas.

Biological activity of neosergeolide and isobrucein B (and two semi-synthetic derivatives) isolated from the Amazonian medicinal plant Picrolemma sprucei (Simaroubaceae)

In the present study, in vitro techniques were used to investigate a range of biological activities of known natural quassinoids isobrucein B (1) and neosergeolide (2), known semi-synthetic derivative 1,12-diacetylisobrucein B (3), and a new semi-synthetic derivative, 12-acetylneosergeolide (4). These compounds were evaluated for general toxicity toward the brine shrimp species Artemia franciscana, cytotoxicity toward human tumour cells, larvicidal activity toward the dengue fever mosquito vector Aedes aegypti, haemolytic activity in mouse erythrocytes and antimalarial activity against the human malaria parasite Plasmodium falciparum. Compounds 1 and 2 exhibited the greatest cytotoxicity against all the tumor cells tested (IC50 = 5-27 µg/L) and against multidrug-resistant P. falciparum K1 strain (IC50 = 1.0-4.0 g/L) and 3 was only cytotoxic toward the leukaemia HL-60 strain (IC50 = 11.8 µg/L). Quassinoids 1 and 2 (LC50 = 3.2-4.4 mg/L) displayed greater lethality than derivative 4 (LC50 = 75.0 mg/L) toward A. aegypti larvae, while derivative 3 was inactive. These results suggest a novel application for these natural quassinoids as larvicides. The toxicity toward A. franciscana could be correlated with the activity in several biological models, a finding that is in agreement with the literature. Importantly, none of the studied compounds exhibited in vitro haemolytic activity, suggesting specificity of the observed cytotoxic effects. This study reveals the biological potential of quassinoids 1 and 2 and to a lesser extent their semi-synthetic derivatives for their in vitro antimalarial and cytotoxic activities.

Detection of dengue virus serotype 3 by reverse transcription - polymerase chain reaction in Aedes aegypti (Diptera, Culicidae) captured in Manaus, Amazonas

The detection of dengue virus serotypes from Aedes aegypti in Manaus, state of Amazonas was carried out using the reverse transcription-polymerase chain reaction technique. Fourteen pools out 82 (17.1 percent) were positive for DENV3, providing a minimal infection rate of 2.1 percent of all analyzed infected female specimens of three different areas of the city.

The residual effect of deltametrine in the control of malaria as observed on different types of walls in the Brazilian Amazon

The residual power of deltametrine FW (25mg l.a/m²) was evaluated and compared to that of DDT (2g i.a./m²) by means of biological tests. The different kinds of material used in constructing houses in Amazonia, such as: masonry, wood, and wattle and daub, were used. Data from logistic regression showed that the drop in mortality, the inclination of the curve in relation to time, was similar for the two insecticides in the first samples. The negative coeficient for the variable, months after application, confirmed a reduction in the activity of both insecticides. Wooden and wattle walls showed positive and negative coeficiencies respectively from the beginning. The wooden walls retained a residual effect but the wattle walls were shown to be the least indicated for the application of insecticides. The experiments demonstrated a more prolonged residual effect for deltametrine as compared to DDT, and that insecticides work better on brick and cement and wooden walls than they do on wattle and daub constructions. For these reasons, it would be necessary to spray brick and cement walls every 8 months, wooden ones every 9 months and wattle constructions every 7 months to control the vectors of malaria

Control of anopheline mosquitos by the spraying of deltamethrin on raffia curtains used in miners' huts in areas endemic for malaria

O poder residual da deltametria FW (25 mg i.a./m2) foi avaliado em cortinas de rafia tecido sintetico, utilizadas na construçäo das barracas nos garimpos. Foram realizadas provas biológicas de parede, durante 420 dias, sendo as cortinas laterais das barracas enroladas durante o dia e desenroladas no final da tarde. Os dados da regressäo logistica evidenciaram que a rafia impregnada com a deltametrina apresenta taxas de mortalidade superiores a tratada com DDT. O poder residual da rafia/deltametrina mostrou efeito elevado, atingindo indices de mortalidade acima de 85 por cento aos 360 dias, diminuindo em quase 50 por cento aos 420 dias. O efeito do DDT foi reduzido aos 180 dias, chegando a zero de mortalidade ao final do experimento. Mediante o resultado do tratamento dado a rafia, recomenda-se seu emprego em barracas nos garimpos e areas endemicas de malaria

Biology of amazonian anopheline: XX. Ontogeny of esterases, leucine aminopeptidase and alpha-glycerophosphate dehydrogenase in Anopheles (Nyssorhynchus) darlingi Root, 1926 (Diptera, Culicidae)

The esterases, leucine aminopeptidase and alpha-glycerophosphate dehydrogenase revealed modifications in gene expressions during the development of Anopheles darlingi. The esterases showed five activity bands, 1 and 2 being more deeply stained during the larval stages than in pupae or adults, esterases 3 and 4 more deeply stained in pupae and adults whereas esterase 5 was present throughout development. Leucine aminopeptidase showed five activity bands: LAP2 and LAP5 were characteristic of larvae, LAP3 was specific for pupae and adults, LAP4 was detected only in pupae, and LAP1 and LAP6 were detected in all stages. Alpha-Glycerophosphate dehydrogenase presented one activity band on starch gel whose intensity increased with development. Two activity bands were detected on polyacrylamide gel (alpha-GPDH1 and alpha-GPDH2) in 4th-instar larvae (old pigmented larvae) and this activity increased with development.

Biology of Amazonian Anopheline mosquitoes. XVI. Evidence of multiple insemination (Poliandry) in Anopheles nuneztovari Gabaldon, 1940 (Diptera:culicidae)

Com base nos resultados da segregaçäo dos alelos de isoenzimas de esterase ESTI*F ESTI*S; EST2*F; ESTI2*S; EST6*M, EST6*s, foi registrada a ocorrência de multipla inseminaçäo efetiva (poliabdria) em populaçöes naturais de Anopheles nuneztovari. Foram estudadas 40 fêmeas captuiradas na natureza, e 8 descendentes por progênie, resultando em um total de 320 individuos analisados. Os resultados evidenciaram que a multipla inseminaçäo ocorre em pelo menos 15% das fêmeas, porém, como nas demais espécies de mosquitos, a monandria (monogamia) é mais frequente (85%). Os seis casos de multipla inseminaçäo constatados para A. nuneztovari, provavelmente, resultam de sucessivas cópulas, ocorridas no espaço de 48 horas, igualmente ao descrito para Culex pipiens L