Credit: CDC
Researchers believe that by analyzing the genome of a mosquito species, they have discovered how that mosquito evolves to withstand a variety of environmental conditions.
The results, published in Genome Biology, provide a better understanding of Anopheles stephensi, a common carrier of malaria in urban environments.
“Anopheles stephensi is emerging as a model mosquito species for genetic and molecular studies,” said Zhijian Jake Tu, PhD, of Virginia Tech in Blacksburg.
He and his colleagues believe their genome map of An stephensi will be an important tool for scientists to identify potential targets for mosquito control. In addition, studies of immunity genes can provide insight into mosquito biology and mosquito-parasite interactions.
“Genome mapping of Anopheles stephensi revealed genetic differences between it and a species especially dangerous for transmitting malaria in Africa, Anopheles gambiae,” said Igor Sharakhov, PhD, also of Virginia Tech.
“This tells us that the sex chromosome is especially prone to mutations that flip chromosomal segments, which, in turn, may promote new, evolved species.”
The researchers assembled more than 92% of the An stephensi genome, and physical mapping assigned 62% of the genome onto chromosomes.
When the team compared An stephensi and An gambiae, they discovered the rate of gene order reshuffling on the Anopheles X chromosome was 3 times higher than that on the autosomes.
An stephensi had more repeat-rich heterochromatin in pericentric regions than An gambiae but fewer repetitive sequences in chromosome arms.
The researchers also identified Y-chromosome contigs and BACs, which represent the most abundant set of Y sequences in any Anopheles species.
Lastly, the team noted that RNA-sequencing and studies of immunity genes provided new insights into mosquito biology and mosquito-parasite interactions.
For instance, FKBP12, a protein that interacts with TOR and TGF-β signaling pathways, showed abundant mRNA expression in a wide range of tissues. This information could help improve our understanding of TOR and TGF-β signaling in mosquitoes.
