Publications by authors named "J R Santos-Mallet"

64 Publications

Anti-Leishmania braziliensis activity of 1,10-phenanthroline-5,6-dione and its Cu(II) and Ag(I) complexes.

Parasitol Res 2021 Sep 7;120(9):3273-3285. Epub 2021 Aug 7.

Laboratório de Estudos Avançados de Microrganismos Emergentes e Resistentes (LEAMER), Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Bloco E-subsolo, Sala 05, Av. Carlos Chagas Filho, 373, Cidade Universitária, Rio de Janeiro, RJ, Brazil.

Leishmaniasis, included in the priority list of the WHO, remains as a neglected disease caused by parasites of the Leishmania genus. There is no vaccine available for human leishmaniasis, and the current treatment is based on old drugs that cause serious side effects. Herein, we initially studied the cellular distribution of the virulence factor gp63, the major metallopeptidase, in a virulent strain of Leishmania braziliensis, and then we measured the inhibitory effects of 1,10-phenanthroline-5,6-dione (phendione), and its metal complexes, [Cu(phendione)](ClO).4HO and [Ag(phendione)]ClO, on both cellular and extracellular metallopeptidases produced by promastigotes. The action of the three compounds on parasite viability and on parasite-macrophage interaction was also determined. Gp63 molecules were detected in several parasite compartments, including the cytoplasm, the membrane lining the cell body and flagellum, and in the flagellar pocket, which explains the presence of gp63 in the culture medium. The test compounds inhibited parasite metallopeptidases in a typical dose-dependent manner, and they also caused a significant and irreversible inhibition of parasite motility. Moreover, the pre-treatment of promastigotes with the test compounds induced a decrease in the association index with macrophages. Collectively, phendione and its Cu(II) and Ag(I) complexes are excellent prototypes for the development of new anti-L. braziliensis drugs.
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http://dx.doi.org/10.1007/s00436-021-07265-xDOI Listing
September 2021

The External Morphology of the Eggs of Culex (Culex) saltanensis (Diptera: Culicidae) Under Scanning Electron Microscopy.

J Med Entomol 2021 05;58(3):1134-1137

Fundação Oswaldo Cruz Piauí, Rua Magalhães Filho 519, Centro, Teresina, PI, Brasil.

The aim of the present study was to describe the morphology of the eggs of Culex (Culex) saltanensis Dyar that occurs in the Neotropical region. Eggs of the Cx. (Cux.) saltanensis were collected at the Mata Atlântica FIOCRUZ campus, fixed in 1% osmium tetroxide, prepared for mounting on metal supports, observed under a scanning electron microscope, and described morphologically. The eggs had a coniform shape with a length of approximately 0.5 mm (505-510 µm) and a width in the median portion of 117 µm (113-123 µm). Upper portion is lined with tubers of irregular shape and varying sizes (0.64-1.31 µm), located on a cross-linked matrix forming bands observed under optical microscopy. The micropyle is encased in a necklace of approximately 6.6-µm plates arranged in a flower-like shape. Comparing Cx. (Cux.) saltanensis eggs with several species of different genera, important divergent characteristics can be observed. However, this study points to the need for new descriptions of eggs of species belonging to the same subgenus in order to analyze if there will be differences between them. Culex (Cux.) saltanensis eggs have particular characteristics not observed in eggs of other Culicidae genera.
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http://dx.doi.org/10.1093/jme/tjaa271DOI Listing
May 2021

External female genitalia of Triatoma jatai, Triatoma costalimai and Triatoma williami (Hemiptera: Reduviidae: Triatominae).

Parasit Vectors 2020 Oct 29;13(1):538. Epub 2020 Oct 29.

Laboratório Interdisciplinar de Vigilância Entomológica em Diptera e Hemiptera, Instituto Oswaldo Cruz - Fiocruz, Rio de Janeiro, Brasil.

Background: Taxonomic identification of triatomines is generally performed based on aspects of their external morphology. However, the use of a multidisciplinary approach, considering morphological aspects of the external genitalia, morphometry, genetics, and phylogeography has been suggested, especially for similar and/or cryptic species. The rupestral species Triatoma jatai Gonçalves et al., 2013, Triatoma costalimai Verano & Galvão, 1959 and Triatoma williami Galvão et al., 1965, which are morphologically similar, have been found naturally infected with Trypanosoma cruzi (Chagas, 1909) in wild, peridomestic, and intradomestic environments, representing a risk of new outbreaks of Chagas disease. This study presents morphological description complementation of these species, with an emphasis on the structures of the female external genitalia, using scanning electron microscopy.

Methods: The females of T. jatai and T. costalimai (n = 10 of each) were captured in the Brazilian municipalities of Paranã and Aurora do Tocantins and were identified with the use of a dichotomous key for the Matogrossensis subcomplex. Females of T. williami (n = 5), were obtained from a laboratory colony. The females were cut transversely at the sixth abdominal segment and examined under scanning electron microscopy (SEM) at the Oswaldo Cruz/Fiocruz Institute Electronic Microscopy Platform.

Results: It was possible to differentiate the three species based on the characteristics of urotergites VII, VIII and IX and urosternite VII, as well as the genital plaques, gonocoxites, and gonapophyses. To our knowledge, morphological differences in the spines present on gonapophysis 8 in triatomines are described here for the first time.

Conclusions: The results show that external genitalia of females are useful structures to differentiate T. costalimai, T. jatai and T. williami. SEM analysis contributes to and corroborates, together with other tools morphological and molecular, the distinction of the three species.
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http://dx.doi.org/10.1186/s13071-020-04418-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7597029PMC
October 2020

Morphological and ultrastructural analysis of an important place of sexual communication of Rhodnius prolixus (Heteroptera: Reduviidae): the Metasternal Glands.

Tissue Cell 2020 Dec 14;67:101416. Epub 2020 Sep 14.

Postgraduate Program of Science and Biotechnology, Instituto de Biologia, Universidade Federal Fluminense, Niteroi, RJ, Brazil; Departamento de Biologia Celular e Molecular, Instituto de Biologia, Universidade Federal Fluminense, Niteroi, RJ, Brazil. Electronic address:

Rhodnius prolixus is an important vector of Trypanosoma cruzi, the etiological agent of Chagas disease. Insect adults have a pair of Metasternal Glands (MGs) and the secretion emitted by these glands acts as sex pheromone. Recent studies have focused on the chemical composition of this pheromone, electrophysiological responses to MGs compounds and mating behavior assays. Morphological studies of these glands are still scarce. Thus, considering the relevance of MGs in the sex pheromone biosynthesis, we investigated the morphology and ultrastructure of R. prolixus MGs. The glandular apparatus presents a tubular structure containing secretory cells with canalicules that fuse with the central duct which conducts the secretion to a pear-shaped reservoir connected to the exterior by a droplet-shape orifice. The secretory cells are classified as class III, they present a well-developed rough and smooth endoplasmic reticulum. Smooth endoplasmic reticulum is a site of lipid biosynthesis that may be involved in the mevalonate pathway, a probable route of the sex pheromone biosynthesis in this insect. The presence of rough endoplasmic reticulum indicates a possible peptides/proteins secretions site which were still not characterized in MGs. Several mitochondria are scattered in the cytoplasm that may suggest a high metabolic activity. Further studies should be carried out to correlate these data with the sex pheromone biosynthesis in this vector.
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http://dx.doi.org/10.1016/j.tice.2020.101416DOI Listing
December 2020

Morphology of the Eggs of Ornithocoris pallidus (Hemiptera, Cimicidae, Haematosiphoninae).

J Med Entomol 2021 01;58(1):486-488

Laboratório Interdisciplinar de Vigilância Entomológica em Diptera e Hemiptera, Instituto Oswaldo Cruz, FIOCRUZ. Rio de Janeiro, RJ, Brasil.

Morphology of cimicid eggs are scarce, and this is the first record for the genus Ornithocoris Pinto, 1927 (Hemiptera: Cimicidae), using scanning electron microscopy (SEM). This genus comprises two species: Ornithocoris toledoi Pinto, 1927 (Hemiptera: Cimicidae) and Ornithocoris pallidus (Usinger, 1959). The eggs of O. pallidus are ellipsoid, and an evident 'lateral flattening', which may give clear asymmetry from the longitudinal axis. The exochorion of the body of the egg and operculum of O. pallidus present spherical or polygonal structures in relief, and pseudomicropyles on the border of the operculum, both differing from Cimex lectularius. The internal face of the operculum is smooth and the border also presented three layers. It was not possible to observe micropyles in the egg of O. pallidus. Bed bugs have a great psychological impact on people, and some people can develop a more or less severe allergic reaction against the bite. Successful control of bed bugs needs serious organization. Studies on egg morphology will add more information to assist in taxonomy studies of O. pallidus and can serve as a basis for control studies because eggs are resistant to insecticides.
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http://dx.doi.org/10.1093/jme/tjaa168DOI Listing
January 2021
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