Assessing the molecular divergence between Anopheles (Kerteszia) cruzii populations from Brazil using the timeless gene: further evidence of a species complex.

Luísa D P Rona,Carlos J Carvalho-Pinto,Alexandre A Peixoto,Carla Gentile,Edmundo C Grisard

doi:10.1186/1475-2875-8-60

Luísa D P Rona, Carlos J Carvalho-Pinto + Show 3 more

Open Access

https://doi.org/10.1186/1475-2875-8-60

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Abstract

BackgroundAnopheles (Kerteszia) cruzii was the most important vector of human malaria in southern Brazil between 1930–1960. Nowadays it is still considered an important Plasmodium spp. vector in southern and south-eastern Brazil, incriminated for oligosymptomatic malaria. Previous studies based on the analysis of X chromosome banding patterns and inversion frequencies in An. cruzii populations from these areas have suggested the occurrence of three sibling species. In contrast, two genetically distinct groups among An. cruzii populations from south/south-east and north-east Brazil have been revealed by isoenzyme analysis. Therefore, An. cruzii remains unclear.MethodsIn this study, a partial sequence of the timeless gene (~400 bp), a locus involved in the control of circadian rhythms, was used as a molecular marker to assess the genetic differentiation between An. cruzii populations from six geographically distinct areas of Brazil.ResultsThe timeless gene revealed that An. cruzii from Itaparica Island, Bahia State (north-east Brazil), constitutes a highly differentiated group compared with the other five populations from south and south-east Brazil. In addition, significant genetic differences were also observed among some of the latter populations.ConclusionAnalysis of the genetic differentiation in the timeless gene among An. cruzii populations from different areas of Brazil indicated that this malaria vector is a complex of at least two cryptic species. The data also suggest that further work might support the occurrence of other siblings within this complex in Brazil.

Highlights

Anopheles (Kerteszia) cruzii was the most important vector of human malaria in southern Brazil between 1930–1960
Between 1930 and 1960, An. cruzii together with Anopheles bellator and Anopheles homunculus, which belong to Kerteszia, were considered the main vectors of malaria when the disease was endemic in southern Brazil
Isolation of An. cruzii timeless gene fragment Different PCR schemes were tested to amplify a fragment of the An. cruzii timeless gene

Summary

Introduction

Anopheles (Kerteszia) cruzii was the most important vector of human malaria in southern Brazil between 1930–1960. Nowadays it is still considered an important Plasmodium spp. vector in southern and south-eastern Brazil, incriminated for oligosymptomatic malaria. Anopheles cruzii is one of the few mosquito species belonging to the subgenus Kerteszia. Between 1930 and 1960, An. cruzii together with Anopheles bellator and Anopheles homunculus, which belong to Kerteszia, were considered the main vectors of malaria when the disease was endemic in southern Brazil. Vector control measures have significantly reduced or even interrupted malaria transmission in some areas, but eradication of the pathogen was not achieved and An. cruzii is still responsible for several oligosymptomatic malaria cases in southern and south-eastern Brazil

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