Significance: We identified a human-specific endogenous retroviral insert (hsERV) that acts as an enhancer for humanPRODH, hsERV_PRODH.PRODHencodes proline dehydrogenase, which is involved in neuromediator synthesis in the CNS. We show that the hsERV_PRODH enhancer acts synergistically with the CpG island ofPRODHand is regulated by methylation. We detected highPRODHexpression in the hippocampus, which was correlated with the undermethylated state of this enhancer.PRODHregulatory elements provide neuron-specific transcription in hippocampal cells, and the mechanism of hsERV_PRODH enhancer activity involves the binding of transcriptional factor SOX2. BecausePRODHis associated with several neurological disorders, we hypothesize that the human-specific regulation ofPRODHby hsERV_PRODH may have played a role in human evolution by upregulating the expression of this important CNS-specific gene.

We investigated the influence of the protein synthesis blocker anisomycin on contextual memory in the terrestrial snail Helix. Prior to the training session, the behavioral responses in two contexts were similar. Two days after a session of electric shocks (5 d) in one context only, the context conditioning was observed as the significant difference of behavioral response amplitudes in two contexts. On the day following testing of context learning, a session of “reminding” was performed, immediately after which the snails were injected with anisomycin or vehicle. Testing of long-term context memory has shown that only anisomycin injections impaired the context conditioning. In control series, the snails were injected after the training session with anisomycin/saline without reminding, and no impairment of the long-term context memory was observed, while injection of anisomycin during the training session completely abolished the long-term memory. No effects of anisomycin on the short-term memory were observed. Surprisingly, injection of anisomycin after the reminding combined with reinforcing stimuli elicited no effect on the context memory. Differences between single-trial and multisession learning are discussed.