title: Altered gene activity correlated with long-term memory formation of conditioned taste aversion in Lymnaea.
abstract: The pond snail Lymnaea stagnalis is capable of learning conditioned taste aversion (CTA) and then consolidating that learning into long-term memory (LTM) that persists for at least 1 month. LTM requires de novo protein synthesis and altered gene activity. Changes in gene activity in Lymnaea that are correlated with, much less causative, memory formation have not yet been identified. As a first step toward rectifying this situation, we constructed a cDNA microarray with mRNAs extracted from the central nervous system (CNS) of Lymnaea. We then, using this microarray assay, identified genes whose activity either increased or decreased following CTA memory consolidation. We also identified genes whose expression levels were altered after inhibition of the cyclic AMP response element-binding protein (CREB) that is hypothesized to be a key transcription factor for CTA memory. We found that the molluscan insulin-related peptide II (MIP II) was up-regulated during CTA-LTM, whereas the gene encoding pedal peptide preprohormone (Pep) was down-regulated by CREB2 RNA interference. We next examined mRNAs of MIP II and Pep using real-time RT-PCR with SYBR Green. The MIP II mRNA level in the CNS of snails exhibiting "good" memory for CTA was confirmed to be significantly higher than that from the CNS of snails exhibiting "poor" memory. In contrast, there was no significant difference in expression levels of the Pep mRNA between "good" and "poor" performers. These data suggest that in Lymnaea MIP II may play a role in the consolidation process that forms LTM following CTA training.
authors.affiliation: Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan.
authors.forename: Sachiyo
authors.initials: S
authors.lastname: Azami
authors.forename: Akiko
authors.initials: A
authors.lastname: Wagatsuma
authors.forename: Hisayo
authors.initials: H
authors.lastname: Sadamoto
authors.forename: Dai
authors.initials: D
authors.lastname: Hatakeyama
authors.forename: Takeshi
authors.initials: T
authors.lastname: Usami
authors.forename: Manabu
authors.initials: M
authors.lastname: Fujie
authors.forename: Ryo
authors.initials: R
authors.lastname: Koyanagi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Azumi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Fujito
authors.forename: Ken
authors.initials: K
authors.lastname: Lukowiak
authors.forename: Etsuro
authors.initials: E
authors.lastname: Ito
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D001522:Behavior, Animal; D050882:CREB-Binding Protein / Q000235:genetics / Q000378:metabolism; D003214:Conditioning, Classical / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D008195:Lymnaea / Q000502:physiology*; D008568:Memory / Q000502:physiology*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D034622:RNA Interference / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013649:Taste
chemical_list: D009479:Neuropeptides; D012333:RNA, Messenger; C063879:insulin-related neuropeptide; D050882:CREB-Binding Protein