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Patients with severe Wernicke–Korsakoff syndrome (WKS) associated with vitamin B1 (thiamine) deficiency (TD) show enduring impairment of memory formation. The mechanisms of memory impairment induced by TD remain unknown. Here, we show that hippocampal degeneration is a potential microendophenotype (an endophenotype of brain disease at the cellular and synaptic levels) of WKS in pyrithiamine-induced thiamine deficiency (PTD) mice, a rodent model of WKS. PTD mice show deficits in the hippocampus-dependent memory formation, although they show normal hippocampus-independent memory. Similarly with WKS, impairments in memory formation did not recover even at 6 months after treatment with PTD. Importantly, PTD mice exhibit a decrease in neurons in the CA1, CA3, and dentate gyrus (DG) regions of the hippocampus and reduced density of wide dendritic spines in the DG. Our findings suggest that TD induces hippocampal degeneration, including the loss of neurons and spines, thereby leading to enduring impairment of hippocampus-dependent memory formation., Graphical abstract PTD mice showed deficits in hippocampus-dependent memory and loss of neurons and spines in the hippocampus.

The degradation of foreign DNAs by restriction enzymes in an edible cyanobacterium, Arthrospira platensis, is a potential barrier for gene-transfer experiments in this economically valuable organism. We overproduced in Escherichia coli the proteins involved in a putative restriction-modification system of A. platensis NIES-39. The protein produced from the putative type II restriction enzyme gene NIES39_K04640 exhibited an endonuclease activity that cleaved DNA within the sequence 5'-CTGCAG-3' between the A at the fifth position and the G at the sixth position. We designated this enzyme AplI. The protein from the adjacent gene NIES39_K04650, which encodes a putative DNA (cytosine-5-)-methyltransferase, rendered DNA molecules resistant to AplI by modifying the C at the fourth position (but not the C at the first position) in the recognition sequence. This modification enzyme, M.AplI, should be useful for converting DNA molecules into AplI-resistant forms for use in gene-transfer experiments. A summary of restriction enzymes in various Arthrospira strains is also presented in this paper.

Pseudomonas jessenii EC-S101 produced hyphal branching-inducing and mitosis-accelerating factors active towards Peronosporomycetes, Aphanomyces cochlioides hyphae. In searching for the active substances, EtOAc-solubles extracted from EC-S101-cultured solid medium were fractionated under the guidance of a paper disc assay using an A. cochlioides mycelium. Two active substances were subsequently isolated and the structure was elucidated by spectroscopic analysis to be (+)-4,5-didehydroacaterin (1) and 3-[(1R)-hydroxyhexyl]-5-methylene-2(5H)-furanone (2), both of which accelerated the mitotic process of A. cochlioides hyphae along with excessive branching at 1.0 microg per disc. These compounds are likely to affect the morphophysiological development of certain eukaryotic organisms in the terrestrial ecosystem.