| dc.description.abstract | The variation of the mannose-binding protein (MBP) gene and the role
of lectins during infection in mosquitoes were investigated using
genomic DNA approach based on sequencing of the gene and the
levels of its expression determined using semi-quantitative Reverse
Transcriptase Polymerase Chain Reaction (RT-PCR) approach.
Using shotgun cloning strategy, sequences were determined from
cloned PCR products obtained from genomic DNA of An.gambiae s.s,
An. arabiensis and An. funestus and aligned following amino acid
translation. BLAST program revealed that MBP-M 1, MBP-13 and MBP-
15 clones showed high homology, with Anopheles protein precusor
A 16 (Accession Q93118). These results were further confirmed by
pairwise alignment using CLUSTAL W program. The remaining clones (
MBP-M2, MBP-MW1, MBP-MW4, MBP-MW5, MBP-MW12, MBP-C1
AND MBP-C15) showed no signature -Of C-type lectin domain but were
closely related based on the positioninq of these genes on the
polytene chromosome. Phylogenetic analysis indicated that MBP-M 1,
MBP-13 and MBP-15 clones are closely related. Since the
representatives of the MBP clones harbour comparatively short
fragments, clustering. of these clones on the nodes supports a more
close phylogenetic relationship between and within Anopheles sp.
RT-PCR analysis showed that MBP is expressed differently with
respect to blood-meal status of the mosquitoes. Altered expression of
MBP may contribute to the risk of disease transmission by the
Plasmodium. The studies also showed that MBP levels decreased with
time post-infection. These changes may disturb normal MBP levels and
create favourable condition for parasite establishment within the
mosquito midgut. These observations raise the possibility that low
levels of MBP may contribute to the increased malaria transmission by
the mosquito and hence Plasmodium plays a key role in its
down-regulation. | en |
