Oleg Gusev 1 , 2 , 3 , Yoshitaka Suetsugu 1 , Richard Cornette 1 , Takeshi Kawashima 4 , Maria D. Logacheva 5 , 6 , 7 , Alexey S. Kondrashov 5 , 8 , Aleksey A. Penin 5 , 7 , 9 , Rie Hatanaka 1 , Shingo Kikuta 1 , Sachiko Shimura 1 , Hiroyuki Kanamori 1 , Yuichi Katayose 1 , Takashi Matsumoto 1 , Elena Shagimardanova 2 , Dmitry Alexeev 10 , Vadim Govorun 10 , Jennifer Wisecaver 11 , Alexander Mikheyev 4 , Ryo Koyanagi 4 , Manabu Fujie 4 , Tomoaki Nishiyama 12 , Shuji Shigenobu 13 , 14 , Tomoko F. Shibata 13 , Veronika Golygina 15 , Mitsuyasu Hasebe 13 , 14 , Takashi Okuda 1 , Nori Satoh 4 , Takahiro Kikawada a , 1
12 September 2014
Anhydrobiosis represents an extreme example of tolerance adaptation to water loss, where an organism can survive in an ametabolic state until water returns. Here we report the first comparative analysis examining the genomic background of extreme desiccation tolerance, which is exclusively found in larvae of the only anhydrobiotic insect, Polypedilum vanderplanki. We compare the genomes of P. vanderplanki and a congeneric desiccation-sensitive midge P. nubifer. We determine that the genome of the anhydrobiotic species specifically contains clusters of multi-copy genes with products that act as molecular shields. In addition, the genome possesses several groups of genes with high similarity to known protective proteins. However, these genes are located in distinct paralogous clusters in the genome apart from the classical orthologues of the corresponding genes shared by both chironomids and other insects. The transcripts of these clustered paralogues contribute to a large majority of the mRNA pool in the desiccating larvae and most likely define successful anhydrobiosis. Comparison of expression patterns of orthologues between two chironomid species provides evidence for the existence of desiccation-specific gene expression systems in P. vanderplanki.
The African chironomid midge, Polypedilum vanderplanki, is able to withstand extreme desiccation. Here the authors sequence the genomes of a desiccation-tolerant and desiccation-sensitive species of chironomid midge and pinpoint genes that may have a role in conferring resistance to desiccation.