title: Identification of anhydrobiosis-related genes from an expressed sequence tag database in the cryptobiotic midge Polypedilum vanderplanki (Diptera; Chironomidae).
abstract: Some organisms are able to survive the loss of almost all their body water content, entering a latent state known as anhydrobiosis. The sleeping chironomid (Polypedilum vanderplanki) lives in the semi-arid regions of Africa, and its larvae can survive desiccation in an anhydrobiotic form during the dry season. To unveil the molecular mechanisms of this resistance to desiccation, an anhydrobiosis-related Expressed Sequence Tag (EST) database was obtained from the sequences of three cDNA libraries constructed from P. vanderplanki larvae after 0, 12, and 36 h of desiccation. The database contained 15,056 ESTs distributed into 4,807 UniGene clusters. ESTs were classified according to gene ontology categories, and putative expression patterns were deduced for all clusters on the basis of the number of clones in each library; expression patterns were confirmed by real-time PCR for selected genes. Among up-regulated genes, antioxidants, late embryogenesis abundant (LEA) proteins, and heat shock proteins (Hsps) were identified as important groups for anhydrobiosis. Genes related to trehalose metabolism and various transporters were also strongly induced by desiccation. Those results suggest that the oxidative stress response plays a central role in successful anhydrobiosis. Similarly, protein denaturation and aggregation may be prevented by marked up-regulation of Hsps and the anhydrobiosis-specific LEA proteins. A third major feature is the predicted increase in trehalose synthesis and in the expression of various transporter proteins allowing the distribution of trehalose and other solutes to all tissues.
authors.affiliation: National Institute of Agrobiological Sciences, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan.
authors.forename: Richard
authors.initials: R
authors.lastname: Cornette
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kanamori
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Nakahara
authors.forename: Oleg
authors.initials: O
authors.lastname: Gusev
authors.forename: Kanako
authors.initials: K
authors.lastname: Mitsumasu
authors.forename: Keiko
authors.initials: K
authors.lastname: Kadono-Okuda
authors.forename: Michihiko
authors.initials: M
authors.lastname: Shimomura
authors.forename: Kazuei
authors.initials: K
authors.lastname: Mita
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kikawada
authors.forename: Takashi
authors.initials: T
authors.lastname: Okuda
mesh_terms: D000818:Animals; D002683:Chironomidae / Q000235:genetics*; D016000:Cluster Analysis; D030541:Databases, Genetic; D003681:Dehydration / Q000235:genetics*; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D015723:Gene Library; D017344:Genes, Insect / Q000235:genetics*; D019476:Insect Proteins / Q000235:genetics; D007814:Larva / Q000235:genetics; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D019476:Insect Proteins