Dataset Information

Molecular Characterization of Anopheles sacharovi Based on Sequences of ITS2-rDNA Region and COI Gene in North of Iran.

ABSTRACT: Background:Malaria is an important mosquito-borne disease considered as one of the public health concerns across many countries. Anopheles mosquitoes are the main vectors of Plasmodium parasites, which cause malaria. Some of these vectors such as Anopheles maculipennis s.l. and Anopheles sacharovi are considered as complex of sibling species distributed in north of Iran. Methods:This study was conducted in north and northwest of Iran including East Azerbaijan, West Azerbaijan, Ardabil, Golestan and North Khorasan provinces with emphasis on the northern borders of the country during 2015-2016. Adult specimens were collected and subjected to morphological identification as well as molecular analysis. Results:Overall, 10405 mosquitoes were collected comprising 21 species. Culex pipiens and Cx. theileri were found as the most frequent species in whole study area. Morphological identification showed that out of 1455 female Anopheles specimens, 77% belonged to An. maculipennis Group. Out of the identified species, ITS2 region and COI gene sequences of 8 An. maculipennis s.s. and 31 An. sacharovi representing all provinces were obtained and submitted to GenBank. The COI sequences for An. sacharovi revealed the presence of 9 haplotypes with similarity of 98.17-100%. Conclusion:Some investigations have reported An. martinius as a member of sibling species of An. sacharovi among Iranian Anopheles genus; while based on our study, there was no evidence of the presence of this species in north and northwest of Iran.

SUBMITTER: Gholami S

PROVIDER: S-EPMC6885140 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Molecular Characterization of <i>Anopheles sacharovi</i> Based on Sequences of ITS2-rDNA Region and COI Gene in North of Iran.

Gholami Sahereh S Bakhshi Hasan H Moosa-Kazemi Seyyed Hassan SH Zahraei-Ramazani Alireza A Chavshin Alireza A Sedaghat Mohammad Mehdi MM

Journal of arthropod-borne diseases 20190624 2

<h4>Background</h4>Malaria is an important mosquito-borne disease considered as one of the public health concerns across many countries. <i>Anopheles</i> mosquitoes are the main vectors of <i>Plasmodium</i> parasites, which cause malaria. Some of these vectors such as <i>Anopheles maculipennis</i> s.l. and <i>Anopheles sacharovi</i> are considered as complex of sibling species distributed in north of Iran.<h4>Methods</h4>This study was conducted in north and northwest of Iran including East Azer ...[more]

PMID: 31803774

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Project description:BackgroundThe Anopheles hyrcanus group includes 25 species, and is widely distributed in the Oriental and Palaearctic regions. Several species within this group are vectors of malaria, lymphatic filariasis and Japanese encephalitis. It is difficult or impossible to identify cryptic species based on their morphological characteristics, with some closely related species of the Hyrcanus Group have similar adult morphological characteristics. Thus, their molecular identification has been an important complementary method to traditional morphological taxonomy.MethodsWe used 461 ribosomal DNA (rDNA) internal transcribed spacer 2 (ITS2) sequences relating to 19 species to reconstruct the molecular phylogeny of the Hyrcanus Group across its range. In addition, we compared the performance of rDNA ITS2 to that of mitochondrial DNA (mtDNA) cytochrome c oxidase subunit 1 gene (cox1) to assess the genetic divergence of Hyrcanus Group sibling species.ResultsBased on Kimura's 2-parameter (K2P) distance model, the average conspecific ITS2 divergence was 0.003, whereas sequence divergence between species averaged 0.480. Average ITS2 sequence divergences were almost 160 times higher among the Hyrcanus Group members than within each species. Two sets of sibling species, An. lesteri Baisas & Hu, 1936 and An. paraliae Sandosham, 1959; and An. sinensis Wiedemann, 1828, An. belenrae Rueda, 2005, and An. kleini Rueda, 2005, were resolved by ITS2. Each of these species was represented as an independent lineage in the phylogenetic tree. Results suggest that An. pseudopictus Grassi, 1899 and An. hyrcanus (Pallas, 1771) are most likely a single species. We uncovered two new ITS2 lineages that require further study before resolving their true taxonomic status, and designed a diagnostic polymerase chain reaction (PCR) assay to distinguish five morphologically similar species.ConclusionsNuclear and mitochondrial genes generally provided consistent results for subgroup division. Compared to cox1, ITS2 is a more reliable tool for studying phylogenetic relationships among closely related mosquito taxa. Based on species-specific differences in ITS2 sequences, the multiplex PCR assay developed here can be used to improve the efficiency of vector identification. Thus, this research will promote the progress of malaria vector surveillance in both epidemic and non-epidemic areas of South and East Asia.

Project description:BackgroundThe Anopheles hyrcanus group, which includes 25 species, is widely distributed in the Oriental and Palaearctic regions. Given the difficulty in identifying cryptic or sibling species based on their morphological characteristics, molecular identification is regarded as an important complementary approach to traditional morphological taxonomy. The aim of this study was to reconstruct the phylogeny of the Hyrcanus group using DNA barcoding markers in order to determine the phylogenetic correlations of closely related taxa and to compare these markers in terms of identification efficiency and genetic divergence among species.MethodsBased on data extracted from the GenBank database and data from the present study, we used 399 rDNA-ITS2 sequences of 19 species and 392 mtDNA-COII sequences of 14 species to reconstruct the molecular phylogeny of the Hyrcanus group across its worldwide range. We also compared the performance of rDNA-ITS2 against that of mtDNA-COII to assess the genetic divergence of closely related species within the Hyrcanus group.ResultsAverage interspecific divergence for the rDNA-ITS2 sequence (0.376) was 125-fold higher than the average intraspecies divergence (0.003), and average interspecific divergence for the mtDNA-COII sequence (0.055) was eightfold higher than the average intraspecies divergence (0.007). The barcoding gap ranged from 0.015 to 0.073 for rDNA-ITS2, and from 0.017 to 0.025 for mtDNA-COII. Two sets of closely related species, namely, Anophels lesteri and An. paraliae, and An. sinensis, An. belenrae and An. kleini, were resolved by rDNA-ITS2. In contrast, the relationship of An. sinensis/An. belenrae/An. kleini was poorly defined in the COII tree. The neutrality test and mismatch distribution revealed that An. peditaeniatus, An. hyrcanus, An. sinensis and An. lesteri were likely to undergo hitchhiking or population expansion in accordance with both markers. In addition, the population of an important vivax malaria vector, An. sinensis, has experienced an expansion after a bottleneck in northern and southern Laos.ConclusionsThe topology of the Hyrcanus group rDNA-ITS2 and mtDNA-COII trees conformed to the morphology-based taxonomy for species classification rather than for that for subgroup division. rDNA-ITS2 is considered to be a more reliable diagnostic tool than mtDNA-COII in terms of investigating the phylogenetic correlation between closely related mosquito species in the Hyrcanus group. Moreover, the population expansion of an important vivax malaria vector, An. sinensis, has underlined a potential risk of malaria transmission in northern and southern Laos. This study contributes to the molecular identification of the Anopheles hyrcanus group in vector surveillance.

Project description:BackgroundThe 5' region of cytochrome oxidase I (COI) is the standard marker for DNA barcoding. However, COI has proved to be of limited use in identifying some species, and for some taxa, the coding sequence is not efficiently amplified by PCR. These deficiencies lead to uncertainty as to whether COI is the most suitable barcoding fragment for species identification of ticks.MethodsIn this study, we directly compared the relative effectiveness of COI, 16S ribosomal DNA (rDNA), nuclear ribosomal internal transcribed spacer 2 (ITS2) and 12S rDNA for tick species identification. A total of 307 sequences from 84 specimens representing eight tick species were acquired by PCR. Besides the 1,834 published sequences of 189 tick species from GenBank and the Barcode of Life Database, 430 unpublished sequences representing 59 tick species were also successfully screened by Bayesian analyses. Thereafter, the performance of the four DNA markers to identify tick species was evaluated by identification success rates given by these markers using nearest neighbour (NN), BLASTn, liberal tree-based or liberal tree-based (+threshold) methods.ResultsGenetic divergence analyses showed that the intra-specific divergence of each marker was much lower than the inter-specific divergence. Our results indicated that the rates of correct sequence identification for all four markers (COI, 16S rDNA, ITS2, 12S rDNA) were very high (> 96%) when using the NN methodology. We also found that COI was not significantly better than the other markers in terms of its rate of correct sequence identification. Overall, BLASTn and NN methods produced higher rates of correct species identification than that produced by the liberal tree-based methods (+threshold or otherwise).ConclusionsAs the standard DNA barcode, COI should be the first choice for tick species identification, while 16S rDNA, ITS2, and 12S rDNA could be used when COI does not produce reliable results. Besides, NN and BLASTn are efficient methods for species identification of ticks.

Dataset Information

Molecular Characterization of Anopheles sacharovi Based on Sequences of ITS2-rDNA Region and COI Gene in North of Iran.

Publications

Molecular Characterization of <i>Anopheles sacharovi</i> Based on Sequences of ITS2-rDNA Region and COI Gene in North of Iran.

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