Molecular characterization and identification of members of the Anopheles subpictus complex in Sri Lanka

BACKGROUND: Anopheles subpictus sensu lato is a major malaria vector in South and Southeast Asia. Based initially on polytene chromosome inversion polymorphism, and subsequently on morphological characterization, four sibling species A-D were reported from India. The present study uses molecular methods to further characterize and identify sibling species in Sri Lanka. METHODS: Mosquitoes from Sri Lanka were morphologically identified to species and sequenced for the ribosomal internal transcribed spacer-2 (ITS2) and the mitochondrial cytochrome c oxidase subunit-I (COI) genes. These sequences, together with others from GenBank, were used to construct phylogenetic trees and parsimony haplotype networks and to test for genetic population structure. RESULTS: Both ITS2 and COI sequences revealed two divergent clades indicating that the Subpictus complex in Sri Lanka is composed of two genetically distinct species that correspond to species A and species B from India. Phylogenetic analysis showed that species A and species B do not form a monophyletic clade but instead share genetic similarity with Anopheles vagus and Anopheles sundaicus s.l., respectively. An allele specific identification method based on ITS2 variation was developed for the reliable identification of species A and B in Sri Lanka. CONCLUSION: Further multidisciplinary studies are needed to establish the species status of all chromosomal forms in the Subpictus complex. This study emphasizes the difficulties in using morphological characters for species identification in An. subpictus s.l. in Sri Lanka and demonstrates the utility of an allele specific identification method that can be used to characterize the differential bio-ecological traits of species A and B in Sri Lanka

Molecular evidence for the presence of malaria vector species a of the Anopheles annularis complex in Sri Lanka

<p>Abstract</p> <p>Background</p> <p><it>Anopheles annularis s.l</it>. is a wide spread malaria vector in South and Southeast Asia, including Sri Lanka. The taxon <it>An. annularis </it>is a complex of two sibling species viz. A and B, that are differentiated by chromosome banding patterns and ribosomal gene sequences in India. Only species A is reported to be a malaria vector in India while the occurrence of sibling species in Sri Lanka has not been documented previously.</p> <p>Findings</p> <p>Anopheline larvae were collected at a site in the Jaffna district, which lies within the dry zone of Sri Lanka, and reared in the laboratory. Emerged adults were identified using standard keys. DNA sequences of the D3 domain of 28S ribosomal DNA (rDNA) and the internal transcribed spacer-2 (ITS-2) of the morphologically identified <it>An. annularis </it>were determined. BLASTn searches against corresponding <it>An. annularis </it>sequences in GenBank and construction of phylogenetic trees from D3 and ITS-2 rDNA sequences showed that the Sri Lankan specimens, and <it>An. annularis s.l</it>. specimens from several Southeast Asian countries were closely related to species A of the Indian <it>An. annularis </it>complex.</p> <p>Conclusions</p> <p>The results show the presence of the malaria vector <it>An. annularis </it>species A in Sri Lanka and Southeast Asia. Because <it>An. annularis </it>vectors have been long associated with malaria transmission in irrigated agricultural areas in the Sri Lankan dry zone, continued monitoring of <it>An. annularis </it>populations, and their sibling species status, in these areas need to be integral to malaria control and eradication efforts in the island.</p

Thermal reactivity of metal oxalate hydrazinates

Metl oxalate hydrazinates MC2O4·2 N2H4 where M=Mg, Mn, Fe, Co, Ni, Cu, Zn and Cd have been prepared and characterised by chemical analysis and infrared spectra. Thermal reactivity and decomposition of these oxalato complexes have been studied using thermogravimetry and differential thermal analysis. Hydrazinates of Mn, Fe, Co, Ni and Cu oxalates exhibit autocatalytic decomposition behaviour whereas the others do not. This phenomenon can be attributed to the presence of a bridged hydrazine as well as the thermal stability of the anhydrous metal oxalates

Thermal reactivity of metal oxalate hydrazinates

Metl oxalate hydrazinates MC2O4·2 N2H4 where M=Mg, Mn, Fe, Co, Ni, Cu, Zn and Cd have been prepared and characterised by chemical analysis and infrared spectra. Thermal reactivity and decomposition of these oxalato complexes have been studied using thermogravimetry and differential thermal analysis. Hydrazinates of Mn, Fe, Co, Ni and Cu oxalates exhibit autocatalytic decomposition behaviour whereas the others do not. This phenomenon can be attributed to the presence of a bridged hydrazine as well as the thermal stability of the anhydrous metal oxalates