A cytotoxic ribonuclease targeting specific transfer RNA anticodons

The carboxyl-terminal domain of colicin E5 was shown to inhibit protein synthesis of Escherichia coli. Its target, as revealed through in vivo and in vitro experiments, was not ribosomes as in the case of E3, but the transfer RNAs (tRNAs) for Tyr, His, Asn, and Asp, which contain a modified base, queuine, at the wobble position of each anticodon. The E5 carboxyl-terminal domain hydrolyzed these tRNAs just on the 3' side of this nucleotide. Tight correlation was observed between the toxicity of E5 and the cleavage of intracellular tRNAs of this group, implying that these tRNAs are the primary targets of colicin E5.     

Schemas and memory consolidation

Memory encoding occurs rapidly, but the consolidation of memory in the neocortex has long been held to be a more gradual process. We now report, however, that systems consolidation can occur extremely quickly if an associative "schema" into which new information is incorporated has previously been created. In experiments using a hippocampal-dependent paired-associate task for rats, the memory of flavor-place associations became persistent over time as a putative neocortical schema gradually developed. New traces, trained for only one trial, then became assimilated and rapidly hippocampal-independent. Schemas also played a causal role in the creation of lasting associative memory representations during one-trial learning. The concept of neocortical schemas may unite psychological accounts of knowledge structures with neurobiological theories of systems memory consolidation.     

Changes of Tight Junction Protein Claudins in Small Intestine and Kidney Tissues of Mice Fed a DDC Diet

DDC (3,5-diethoxycarbonyl-1,4-dihydrocollidine)-fed mice are widely used as a model for cholestatic liver disease. We examined the expression of tight junction protein claudin subspecies by immunofluorescent histochemistry in small intestine and kidney tissues of mice fed a DDC diet for 12 weeks. In the small intestine, decreases in claudin-3, claudin-7 and claudin-15 were observed in villous epithelial cells corresponding to the severity of histological changes while leaving the abundance of these claudin subspecies unchanged in crypt cells. Nevertheless, the proliferative activity of intestinal crypt cells measured by immunohistochemistry for Ki-67 decreased in the mice fed the DDC diet compared with that of control mice. These results suggest the possibility that DDC feeding affects the barrier function of villous epithelial cells and thus inhibits the proliferative activity of crypt epithelial cells. On the other hand, in the kidney, remarkable changes were found in the subcellular localization of claudin subspecies in a segment-specific manner, although histological changes of renal epithelial cells were quite minimal. These results indicate that immunohistochemistry for claudin subspecies can serve as a useful tool for detecting minute functional alterations of intestinal and renal epithelial cells.     

Binding effect of cellulose nanofibers in wood flour board

Wood-based materials are extensively used for residual construction worldwide, especially in Japan. Most wood-based materials are fabricated using adhesives, some of which are not environmentally friendly. As an alternative to chemical adhesives, we explored this issue using nanofiber technology, especially the use of cellulose nanofibers (CNF), as reinforcement in wood flour (WF) board to replace chemical adhesives. We found that CNF could be easily made by pulverization in a ball mill. The physical and mechanical properties of WF board were improved by the three-dimensional binding effects of the CNF.     

No Mutations of Lysophosphatidic Acid Receptor Genes in Lung Adenocarcinomas Induced by N-Nitrosobis(2-hydroxypropyl)amine in Rats

Lysophosphatidic acid (LPA) is a bioactive phospholipid that stimulates cell proliferation and migration, and protects cells from apoptosis. It interacts with specific G protein-coupled transmembrane receptors. Recently, frequent mutations of the LPA receptor-1 (LPA1) gene were detected in rat lung adenocarcinomas induced by N-nitrosobis(2-hydroxypropyl)amine (BHP). In this study, to evaluate the involvement of other LPA receptor gene alterations during lung carcinogenesis, we investigated mutations of the LPA2, LPA3, LPA4 and LPA5 genes in lung adenocarcinomas induced by BHP in rats. Fifteen male Wistar rats, 6 weeks of age, were given 2000 ppm BHP in their drinking water for 12 weeks and then maintained without further treatment until sacrifice at 25 weeks, and 15 adenocarcinomas were obtained. Genomic DNAs were extracted from frozen tissues, and the LPA2, LPA3, LPA4 and LPA5 genes were examined for mutations, using polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis. No mutations of LPA2, LPA3, LPA4 and LPA5 were detected in the 15 adenocarcinomas. These results suggest that alterations due to LPA2, LPA3, LPA4 and LPA5 gene mutations might not be involved in the development of lung adenocarcinomas induced by BHP in rats.     

Large-area three-dimensional molecular ordering of a polymer brush by one-step processing

Rational molecular design and processing, enabling large-area molecular ordering, are important for creating high-performance organic materials and devices. We show that, upon one-step hot-pressing with uniaxially stretched Teflon sheets, a polymer brush carrying azobenzene-containing mesogenic side chains self-assembles into a freestanding film, where the polymer backbone aligns homeotropically to the film plane and the side chains align horizontally. Such an ordered structure forms through translation of a one-dimensional molecular order of the Teflon sheet and propagates from the interface macroscopically on both sides of the film. The resultant wide-area bimorph configuration allows the polymer film to bend rapidly and reversibly when the azobenzene units are photoisomerized. The combination of polymer brushes with hot-pressing and Teflon sheets provides many possibilities in designing functional soft materials.     

Anaphylaxis after rabies vaccination for dogs in Japan

Severe adverse reactions after rabies vaccination in dogs were examined from 317 cases reported to the Ministry of Agriculture, Forestry and Fisheries (MAFF) in Japan during 15-year period from April 2004 to March 2019. We found that 109 of the 317 dogs showed anaphylaxis (0.15/100,000 vaccinated dogs), and 71 of the 109 cases of anaphylaxis resulted in death (0.10/100,000 vaccinated dogs). We measured bovine serum albumin (BSA) in four commercially available rabies vaccines and found the levels ranged from 0.1 to 16.6 µg/dose. Our survey showed that the rate of anaphylaxis to rabies vaccines in dogs is rare, although some cases of anaphylaxis resulted in death. Veterinarians should be well prepared to deal with vaccine-associated anaphylaxis.     

Species richness of the understory woody vegetation in Japanese cedar plantations declines with increasing number of rotations

The possibility of restoring natural broadleaf forests may be decreased by the effects of plantation management, particularly in sites that undergo repeated rotation. We investigated the following two working hypotheses about the effects of repeated plantation of conifers on the natural regeneration of woody saplings in cool-temperate Japanese cedar plantations: (1) that repeated plantation of conifers decreases sapling species richness, and (2) that repeated plantation of conifers changes sapling species compositions. Our result supported the first hypothesis, because species richness was significantly lower in second-rotation plantations than in first-rotation plantations. The second hypothesis was not supported, because no significant or substantial differences in species composition were observed between plantations with different numbers of rotations. However, the abundance of tree (nonshrub) and gravity-dispersed species decreased after the second rotation of large saplings, albeit not those of small saplings, suggesting that response to repeated rotation depended on sapling size. Our results suggest that it is important to consider factors affecting the maintenance of a species in the plantations, such as distance from natural forests and seed sources, to minimize the effects of repeated plantation.