AsianScientist (Sep. 18, 2014) – An international team of researchers, including a group from Okinawa Institute of Science and Technology Graduate University, have analysed the genetic material of a resilient species of midge (small fly) from Nigera that can survive even the airless vaccuums of space. The findings have been published in Nature Communications.
The midge, Polypedilum vanderplanki, lives in an environment in northern Nigeria where the dry season lasts for at least six months and droughts can last up to eight months. By the time eggs have hatched and larvae have developed, the pools of water they breed in dry up. However, such dried larvae can survive in a dehydrated state for more than 17 years.
The unusual resilience of P. vanderplanki can be attributed to anhydrobiosis, a unique state that allows an organism to survive even after losing 97 percent of its body water. Anhydrobiotic organisms are also able to survive other severe conditions such as extreme temperatures ranging from 90°C to -270°C, vacuums and high doses of radiation; all of which would be lethal to most other life forms.
The extent of dehydration that these African midges can withstand can very badly damage DNA. However organisms like P. vanderplanki also have the ability to make significant structural repairs to their DNA after being rehydrated.
Comparative analysis between P. vanderplanki and one of its closer relatives, Polypedilum nubifer, shows significant variations in the genes connected with anhydrobiosis. The results of the study show that many of the genes P. vanderplanki possess are exclusive to its genetic code and not something passed down from an ancestral species nor are they shared by its close relatives. This means that the midge is not just unique, but an excellent resource for study as those exclusive gene sequences possessed by P. vanderplanki are readily identifiable in gene clusters known as anhydrobiotic related gene Islands.
According to the scientists, members of these gene clusters have direct involvement with the midge’s ability to neutralize DNA dessication under extreme conditions. They expect many potential applications for elucidating this mechanism; for example in the storage and transport of biological specimens.
The researchers also hope that their findings will lead to a greater understanding of how this resilient, unique insect evolved.
The article can be found at Gusev et. al (2014) Comparative genome sequencing reveals genomic signature of extreme desiccation tolerance in the anhydrobiotic midge.
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Source: Okinawa Institute of Science and Technology Graduate University.
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