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Title: Molecular and evolutionary genetics of Anopheles gambiae s.l, a malaria vector in Africa
Author: Dadzie, Samuel Kweku
ISNI:       0000 0004 2672 5704
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2008
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One of the most important areas of research regarding adaptation of malaria vectors that has received very little attention is the effect of selection on the population structure of An. arabiellsis and the ecological significance of melanisation on the ability ofAn. gambiae to surVive in different habitats. Most microsatellite-based studies of population structure have selected loci that are located within inversions many of which may be subject to selection. The structure of the population will therefore depend on the nature of the selection on the selected loci and the effect of other nearby loci. Locus 33Cl within chromosome 3Ra inversion of An. gambiae showed abberation in the genetic differentiation of An. arabiellsis population sampl~d from the north-south transect of East Africa (Donnelly and Townson 2000).The aim of the first part of this thesis which constituted Chapter 3 is to determine if there is any signature of positive selection on some candidate loci located within the 3Ra inversion and investigate its effect on nucleotide variation ofAn. arabiellsis populations. In line with this objective, we obtained 20 sequences each of 4 Epsilon class Glutathione S-transjerases (GSTs) i.e. (GSTEl, 441 bp (n=20), GSTE2, 800bp (n=20), GSTE6, 735bp (n=20) and GSTE8, 796bp (n=20) from samples of An. arabiellsis captured from Sudan, Ethiopia, Malawi and Tanzania. Glutathione s-transferases (GSTs) are detoxication enzymes that are involved in the metabolism, detoxication and excretion of a large number of endogenous and exogenous compounds including DDT from the cells of organisms. Using evolutionary models, we showed that 3 out of the 4 loci deviated from neutral expectations. This is indicative of selective constraints on these loci. Pairwise estimates of population differentiation, Fsr values were far in excess of those observed from microsatellite-based studies of the same samples with specimen from Ethiopia much more genetically differentiated from the rest.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral