950 resultados para MORPHOLOGICAL CHARACTERS


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A new genus, Oswaldotrema gen. nov. is proposed. Oswaldotrema nacinovici sp. nov. is descibed from Numenius phaeopus Latham, 1790. Differentiation from the other related genera, namely Philophthalmus, Pygorchis, Proctobium, Parorchis, Echinostephila, Cloacitrema, Pittacium, Ophthalmotrema, Skrjabinovermis and Paratrema, was based on morphological characters, mainly on those referring to the body surface, body shape, head, esophagus, pharynx, acetabulum, vitellaria, vitelline reservoir and seminal vesicle.

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In Cuba, several Biomphalaria species have been reported such as B. orbignyi, B. schrammi, B. helophila, B. havanensis and B. peregrina; only the latter three are considered as potential hosts of Schistosoma mansoni. The specific identification of Biomphalaria species is based on anatomical and morphological characters of genital organs and shells. The correct identification of these snails is complicated by the high variation in these characters, similarity among species and in some cases by the small size of the snails. In this paper, we reported the classical morphological identification, the use of PCR and RFLP analysis of the internal transcribed spacer region of the ribosomal RNA genes for molecular identification of seven snail populations from different localities in Cuba. Using morphological and molecular analysis, we showed that among the studied Cuban Biomphalaria populations only B. havanensis and B. obstructa species were found.

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Females of Ixodes (Haemixodes) uruguayensis Kohls & Clifford, 1967, a species whose adults were unknown until the present, were obtained in the laboratory from engorged nymphs collected on rodents (Scapteromys tumidus and Oxymycterus nasutus) in the counties of Maldonado and San José, Uruguay. Morphological characters of these females were identical to those given in the description of the female of Ixodes longiscutatum Boero, 1944. I. uruguayensis is, thus, relegated to a junior subjective synonym of I. longiscutatum. However, because of the unique morphological characters of the immature stages, the validity of the subgenus Haemixodes Kohls & Clifford, 1967 is not questioned. Therefore, the new status of Ixodes (Haemixodes) uruguayensis Kohls & Clifford, 1967 is Ixodes (Haemixodes) longiscutatum Boero, 1944.

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Anopheles galvaoi, a member of the subgenus Nyssorhynchus, is redescribed based on morphological characters of the adults male and female, fourth-instar larva and pupa. Female, male genitalia, larval and pupal stages are illustrated. Data about medical importance, bionomics, and distribution are given based on literature records. Adult female of An. galvaoi can be easily misidentified as An. benarrochi Gabaldón and An. aquasalis Curry. A few characters are indicated for identifying female and immatures of An. galvaoi. Phylogenetic relationships among An. galvaoi and six other species of the Oswaldoi Subgroup are estimated using COII mtDNA and ITS2 rDNA gene sequences. Lectotype of An. galvaoi, an adult female from Rio Branco, State of Acre, is invalidated.

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An isoenzymatic comparative analysis of the variability and genetics differentiation among Anopheles species was done in populations of An. (Nys.) intermedius and An. (Ano.) mattogrossensis of the Anopheles subgenus, and of An. darlingi, An. albitarsis and An. triannulatus of the Nyssorhynchus subgenus, with the aim of detecting differences between both subgenera and of estimating the degree of genetic intere specific divergence. Samples from Macapá, State of Amapá and Janauari Lake, near Manaus, State of Amazonas, were analyzed for eight isoenzymatic loci. Analysis revealed differences in the average number of alleles per locus (1.6-2.3) and heterozygosity (0.060-0.284). However, the proportion of polymorphic loci was the same for An. (Nys.) darlingi, An. (Nys.) triannulatus and An. (Ano.) mattogrossensis (50%), but differed for An. (Nys.) albitarsis (62.5%) and An. (Ano.) intermedius (25%). Only the IDH1 (P > 0.5) locus in all species studied was in Hardy-Weinberg equilibrium. The fixation index demonstrated elevated genetic structuring among species, based on values of Fst = 0.644 and genetic distance (0.344-0.989). Genetic difference was higher between An. (Nys.) triannulatus and An. (Ano.) intermedius (0.989) and smaller between An. (Nys.) albitarsis sensu lato and An. (Nys.) darlingi (0.344). The data show interspecific genetic divergence which differs from the phylogenetic hypothesis based on morphological characters.

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Freshwater snails belonging to the genus Biomphalaria act as intermediate hosts for the parasite trematode Schistosoma mansoni in Africa and in the neotropical region. Identification of such molluscs is carried out based on morphological characters and the presence of cercariae is verified through squeezing snails between two glass slides or by exposing them to artificial light. However, sometimes, the material collected includes molluscs with decomposed bodies or, yet, only empty shells, which precludes their identification and S. mansoni detection. Due to these difficulties, we have developed a methodology in which DNA may be extracted from traces of organic material from inside shells in order to identify molluscs through polymerase chain reaction and restriction fragment length polymorphism and to detect S. mansoni into these snails, by using low stringency polymerase chain reaction. Species-specific profiles obtained from B. glabrata, B. straminea, and B. tenagophila snails and their shells, maintained in laboratory for ten years, showed the same profiles. S. mansoni profiles showed to be present in shell specimens as far as the eighth week after being removed from aquarium.

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The specific identification of Lymnaeid snails is based on a comparison of morphological characters of the shell, radula, renal and reproductive organs. However, the identification is complicated by dissection process, intra and interspecific similarity and variability of morphological characters. In the present study, polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) techniques targeted to the first and second internal transcribed spacers (ITS1 and ITS2) rDNA and to the mitochondrial 16S ribosomal gene (16S rDNAmt) were used to differentiate the species Lymnaea columella, L. viatrix, and L. diaphana from some localities of Brazil, Argentina, and Uruguay as well as to verify whether the molecular results corroborates the classical morphological method.PCR-RFLP analysis of the ITS1, ITS2, and 16S using 12 restriction enzymes revealed characteristic patterns for L. columella and L. diaphana which were concordant with the classical morphology. On the other hand, for L. viatrix populations a number of 1 to 6 profiles were generated while morphology provided the species pattern results.

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Anopheles (Nyssorhynchus) benarrochi, An. (N.) oswaldoi, and An. (N.) rangeli are the most common anthropophilic mosquitoes in the southern Colombian state of Putumayo. Adult females are most commonly collected in epidemiological studies, and this stage poses significant problems for correct identification, due to overlapping inter-specific morphological characters. Although An. rangeli is easy to identify, the morphological variant of An. benarrochi found in the region and An. oswaldoi are not always easy to separate. Herein we provide a rapid molecular method to distinguish these two species in Southern Colombia. Sequence data for the second internal transcribed spacer (ITS2) region of rDNA was generated for link-reared progeny of An. benarrochi and An. oswaldoi, that had been identified using all life stages. ITS2 sequences were 540 bp in length in An. benarrochi (n = 9) and 531 bp in An. oswaldoi (n = 7). Sequences showed no intra-specific variation and ungapped inter-specific sequence divergence was 6.4%. Species diagnostic banding patterns were recovered following digestion of the ITS2 amplicons with the enzyme Hae III as follows: An. benarrochi (365, 137, and 38 bp) and An. oswaldoi (493 and 38 bp). This polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay provides rapid, accurate, and inexpensive species diagnosis of adult females. This will benefit future epidemiological studies and, as PCR amplification can be achieved using a single mosquito leg, the remaining specimen can be either retained as a morphological voucher or further used in vector incrimination studies. That An. benarrochi comprises a complex of at least two species across Latin America is discussed.

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Several species of the subgenus Psychodopygus Mangabeira, 1941 are known to be leishmaniosis vectors in Brazil. Some of them are morphologically similar, which makes their identification quite difficult concerning epidemiological studies. The aim of the current work is to study the morphology of adult specimens of the subgenus Psychodopygus, in accordance with the morphological similarity and still taking into account the epidemiological importance of some species. Thus 11 species have been studied, including four subspecies of adult specimens deposited in the phlebotomine collection of Centro de Pesquisas René Rachou-Fiocruz. Morphological characters found in the literature and new features observed in this study were recorded in a taxonomic discussion format. These characters make it easy to separate such species. Four taxa, previously considered as subspecies, were raised to the category of species.

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Panstrongylus mitarakaensis n. sp. is described from French Guiana. Morphological characters are provided. This small species, less robust than other Panstrongylus species, shows a pronotum shape similar to species of the "P. lignarius complex". However, others characters such as the postocular part of head, the obsolete tubercle on the anterior lobe of pronotum, and the lateral process on the antenniferous tubercle distinguish it from the species in that complex. The taxonomic key of the genus Panstrongylus is actualized.

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Anopheles (Nyssorhynchus) lanei Galvão and Amaral is here redescribed using morphological characteristics of adult, male and female, fourth instar larva and pupa. The larva, pupa, and male genitalia are illustrated. Diagnostic morphological characters of adults, male genitalia, fourth instar larva and pupa are provided to distinguish An. lanei from other species of the Argyritarsis section. Species distribution data are based on the published literature records and bionomics data are based on both literature records and field data.

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Anopheles (Nyssorhynchus) atacamensis, a new species in the subgenus Nyssorhynchus, is described and validated using morphological characters of the male and female adult, male genitalia and immature stages. Molecular characterization employing sequences of the ITS2 rDNA and COI mtDNA are provided. The new taxon is compared with Anopheles (Nyssorhynchus) pictipennis (Philippi) from central Chile based on morphological features of the adults, male genitalia and larva. Illustrations of the diagnostic characteristics of the male genitalia, fourth-instar larva and pupa are provided.

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Anopheles (Nyssorhynchus) pristinus Nagaki & Sallum, n. sp. of the Myzorhynchella Section is described based on morphological characters of adult females, males, fourth-instar larvae, pupae and male genitalia. Anopheles (Nyssorhynchus) antunesi Galvão & Amaral is characterized to fix its identity and distinguish it from An. pristinus. The eggs of An. antunesi are described for the first time. Molecular characterization employing sequences of the COI mitochondrial gene and the ITS2 region of ribosomal DNA are provided for each species. An. antunesi and An. pristinus are compared with morphologically similar species of the Myzorhynchella Section. The results of the present study suggest that the new species has been misidentified as both An. antunesi and Anopheles lutzii Cruz. An. antunesi and An. pristinus are sympatric, occurring at high altitudes in Serra da Mantiqueira, Southeastern Brazil.

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Specific genetic profiles of Brazilian Biomphalaria species were previously standardized by molecular taxonomy through the analysis of restriction fragments, which were generated by digesting the internal transcribed spacer region of rDNA with the DdeI endonuclease. Biomphalaria amazonica displayed three distinct profiles. To investigate these distinct profiles, the same molecular technique, polymerase chain reaction and restriction fragment length polymorphism, was used with different endonucleases. In addition, morphological data were also used to compare B. amazonica specimens that were collected from Brazil, Colombia and Bolivia. The morphological characters of Bolivian molluscs were similar to B. amazonica, displayed a molecular profile of five restriction fragments and morphological data, whereas the Colombian mollusc population showed morphological characters similar to Biomphalaria cousini and a molecular profile of three restriction fragments, similar to B. cousini. The Brazilian specimens showed the B. amazonica and B. cousini molecular profiles as well as a third profile, which resembled a combination of the Colombian and Bolivian molecular profiles.

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We present filaria-nested polymerase chain reaction (PCR), which is based on amplification of first internal transcribed spacer rDNA to distinguish three parasitic filarial species (Onchocerca volvulus, Mansonella ozzardiand Mansonella perstans) that can be found in the Amazon Region. Nested PCR-based identifications yielded the same results as those utilizing morphological characters. Nested PCR is highly sensitive and specific and it detects low-level infections in both humans and vectors. No cross-amplifications were observed with various other blood parasites and no false-positive results were obtained with the nested PCR. The method works efficiently with whole-blood, blood-spot and skin biopsy samples. Our method may thus be suitable for assessing the efficacy of filaria control programmes in Amazonia by recording parasite infections in both the human host and the vector. By specifically differentiating the major sympatric species of filaria, this technique could also enhance epidemiological research in the region.