Injecting mosquitoes with bacteria could stop dengue fever…
Injecting bacteria into mosquitoes can block them from transmitting the dengue virus and help control the spread of a disease that kills 20,000 people a year in more than 100 countries.
In two papers published in the journal Nature, researchers in Australia showed how female mosquitoes infected with the Wolbachia bacteria passed the bug easily to their offspring, making them all dengue-free. They said such infected mosquitoes should be released into the wild, so that the spread of dengue to people may be reduced. Professor Scott O'Neill, lead author and science faculty dean at Monash University stated that "The main feature was their ability to reduce dengue transmission," and "It almost completely abolished dengue virus in the body of the mosquito."
In their experiment, O'Neill and his colleagues injected the bacteria into more than 2,500 embryos of Aedes aegypti mosquitoes that can spread dengue fever. After they hatched, they were treated to blood meals laced with the dengue virus, and none picked up the virus.
"The [Wolbachia] bacteria doesn't spread environmentally. It gets passed on from mother to children through the eggs."
"When an infected male mates with an uninfected female, all her eggs die. That gives an indirect benefit to the females with Wolbachia because when they mate with infected males, their eggs hatch normally ... all their eggs have Wolbachia in them so Wolbachia gets more and more common with every generation."
O'Neill said there were two theories to explain why the Wolbachia was able to block the uptake of dengue.
One was that the Wolbachia boosts the mosquito's immune system and protects it from viruses such as dengue. The second was that the Wolbachia competes with dengue for food inside the mosquito, making it harder for the dengue virus to replicate.
More than 50 million people in more than 100 countries fall sick and 20,000 die each year from dengue fever. There is no vaccine or specific treatment for the disease. The only method of prevention is to control mosquito populations through eliminating breeding sites and using insecticides.
O'Neill's team released nearly 299,000 infected mosquitoes in January at more than 370 sites in north-eastern Australia, and the bacteria spread into the wild mosquito population successfully, with their offspring also infected over a three-month period.
The team is seeking approval to release such infected mosquitoes into dengue-endemic sites in Vietnam, Thailand, Indonesia and Brazil to see if it reduces rates of dengue transmission in people.
"It is an alternative strategy for dengue control which could be low-cost and sustainable and suitable for deployment in large urban cities in the developing world."
Unraveling Potato Genome Paves Way for New Varieties
The potato, number three on the list of the world's most popular food, has been genetically unraveled. Researchers from the Plant Breeding department at Wageningen UR (University & Research centre) and other colleagues involved in the international Potato Genome Sequencing Consortium (PGSC) in 14 countries have mapped the potato's hundreds of millions of building blocks. Their findings are reported in Nature.
The 844 million base pairs in the DNA which form the potato's genome possess a surprisingly large number of genes, 39,000. These carry the information for proteins which stimulate the growth and development of the plant. The location of nearly all the genes on one of the twelve chromosomes of the potato is now known.
The data shows that because each potato gene has four possible different versions, the total genetic diversity is very high. However due to the import from South America of a limited set of potato genotypes in the 16th century, there is a relatively narrow genetic base in modern varieties. The unravelling of the genome sequence now opens the way for a systematic and rapid analysis of the huge genetic potential in the wild gene pool.
Now that the sequence of the building blocks of the potato genome is known, this paves the way for researchers and breeders to raise the yield of the crop, improve its quality and nutritional value as well as make the plant more resistant to disease. Crossing disease-resistant characteristics usually takes up to fifteen years and this process can now be considerably reduced.
The potato is the most important food crop that is not a grain (wheat, rice). According to the World Food and Agriculture Organisation (FAO), global production is around 330 million tons a year. Potatoes are an important source of starch, protein, antioxidants and vitamins, for both man and animal, while starch can be used for green materials, including paper and textiles.
The potato acreage has changed very little in recent decades. While the cultivation area in Eastern Europe shrank, it tripled in developing countries. For these countries, the potato has become an attractive crop, because potato plants use water and nutrients efficiently and potato growers increasingly have access to good seeds.
These seeds often come from Dutch growers. There are over 4000 cultivated potato varieties, often known by strange names like Desiree, Agria, Maris Piper and Bintje.