(Phys.org) —In the battle against the mosquitoes that carry deadly human diseases scientists are recruiting a new ally: a genetic enemy within the mosquito's DNA.
These new recruits are homing endonuclease genes (HEGs), 'selfish' genetic elements that have a better than normal chance of being passed on between generations despite being potentially harmful to an individual.
HEGs can recognise and 'cut' a short sequence of DNA on one of a pair of chromosomes, then fool an organism's repair mechanism into copying the HEG across onto the other chromosome. The HEG gets inserted within the 'cut' sequence of 'normal' DNA whilst the 'cut' is repaired. It is this 'drive' that makes HEGs particularly interesting for disrupting DNA and hence mosquito control.
Crucially HEGs can be used to recognise and disrupt a bit of DNA that really matters – that is important for an individual mosquito to survive from egg to adult.
'HEGs occur naturally in some simple organisms, such as single-celled fungi, and have been artificially inserted into the genomes of other organisms, notably the mosquito species, Anopheles gambiae, that is the main vector of human malaria,' explains Mike Bonsall of Oxford University's Department of Zoology.
'They can be used either to suppress mosquito populations by altering the inheritance patterns of genes (for example genes that affect survival) or to alter the genetic structure of mosquito populations by driving genes that alter the key mosquito characteristics (such as the ability to transmit a pathogen).'
Such a genetic approach could be an important weapon against diseases like malaria, which is responsible for up to 1.6 million deaths a year worldwide, by reducing the numbers of disease-carrying adult female mosquitoes in a local area to such a level that there aren't enough to support and pass on the infection to humans...
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More information: Nina Alphey and Michael B. Bonsall. "Interplay of population genetics and dynamics in the genetic control of mosquitoes." J. R. Soc. Interface April 6, 2014 11 93 20131071; DOI: 10.1098/rsif.2013.1071 1742-5662
Movement of genes
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| The study found that the African malaria mosquito Anopheles gambiae has significant exchange of genes between the two groups. Credit: Anthony "Anton" Cornel/UC Davis |
(Phys.org) —A new study by researchers at the University of California, Davis, and in Mali finds that many of the assumptions underlying current thinking about the genetics of two key subgroups of malaria mosquitoes are false.
For the past decade, scientists around the world have intensely studied the two forms of the African malaria mosquito, Anopheles gambiae. It was thought that the mosquitoes in the two subgroups—known as the M and S forms—rarely mated outside of their groups, and, just this year, the two were recognized as distinct species.
The new study shows, however, that although the M and S subgroups have developed distinct genetic profiles, there actually continues to be significant exchange of genes between the two groups due to crossbreeding. These findings appear online in the Nov. 19 Early Edition of the Proceedings of the National Academy of Sciences.
Developing an accurate picture of gene flow through matings within and between these two mosquito groups could prove key to preventing the spread of malaria. The deadly mosquito-transmitted disease annually kills more than 660,000 people around the world, mostly in Africa.
In this study, lead authors Gregory Lanzaro and Yoosook Lee, both medical entomologists in the UC Davis School of Veterinary Medicine, and their colleagues showed that hybridization, or mating, between the M and S groups was far higher than previously assumed.
"It is critical that we understand the movement of genes between these two forms of the African malaria mosquito," Lanzaro said....
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