Biology subjects

Yamazaki, A.

Publications and source records attributed to Yamazaki, A..

4 recordsLinked to original sources

bioRxiv2025

Early onset memory deficit of WMI rats compared to their nearly isogenic WLIs is reversed by enriched environment in females

We tested the hypothesis that environmental enrichment (EE) can attenuate early-onset cognitive decline in a stress-hyperresponsive rat strain. The novel genetic model, the Wistar Kyoto More Immobile (WMI) inbred rat strain demonstrates increased stress reactivity and enhanced depression-like behavior compared to its nearly isogenic control, the Wistar Kyoto Less Immobile strain (WLI). Middle-aged (12 months) WMI females exhibited diminished fear, and spatial memory in the contextual fear conditioning and Morris Water Maze paradigms, respectively, compared to young animals (6 months) of both strains and to middle-aged WLIs. Middle-aged WMI males showed a lesser age-induced deficit. EE from six to 12 months of age reversed these memory deficits in middle-aged WMI females and attenuated them in WMI males. Plasma levels of estradiol followed the same pattern as memory in WMI females following EE. RNA sequencing from female hippocampi revealed significant strain, age, and enrichment-induced differentially expressed genes. Among these, solute carrier family 35, member A4 (Slc35a4) and potassium inwardly rectifying channel, subfamily J, member 2 (Kcnj2) were confirmed to show hippocampal expression changes parallel to that of memory in the WMI. These genes have critical roles in the integrated stress response, cellular metabolism, and the effects of stress on neurovascular coupling, respectively. Pathway analyses revealed the involvement of oxidative phosphorylation and mitochondrial dysfunction in the hippocampal processes of aging and EE-induced reversal. These findings underscore the critical involvement of molecular stress responses in early-onset memory decline and suggest potential therapeutic targets for age-related cognitive impairment. HighlightsO_LIHeightened innate stress response and depression leads to early onset memory decline C_LIO_LIEnriched environment reverses memory decline of middle-aged females C_LIO_LIEnriched environment also reverses declining estrogen levels of middle-aged females C_LIO_LIMitochondrial dysfunction may underly mid-life cognitive and molecular changes C_LI

animal behavior and cognition↗

bioRxiv2024

Non-viral derivation of induced pluripotent stem cells from the canine umbilical cord

In our previous study, canine induced pluripotent stem cells (iPSCs) were successfully generated from skin-derived fibroblasts, without the use of viral vectors. However, for clinical application of canine iPSCs in veterinary regenerative medicine, iPSCs generated from less invasive cell sources would be desirable. Therefore, the purpose of this study was to generate iPSCs from canine umbilical cords discarded at fetal birth. Canine umbilical cords were cut into small pieces and cultured in Dulbeccos modified Eagles medium supplemented with 10% fetal bovine serum. Episomal vectors carrying 10 reprogramming gene sets were introduced into fibroblasts obtained from the umbilical cord using electroporation. When putative iPSCs colonies emerged, constitutive cell characterization was performed to evaluate cell morphology, proliferative potential, alkaline phosphatase staining, expression of stem cell markers, and the ability to differentiate into a trilineage following embryoid body and teratoma formation. Multiple putative iPSC colonies formed when reprogramming gene sets were introduced into fibroblasts obtained from the canine umbilical cord. The resulting colony cells stained positive for alkaline phosphatase, and showed expression of OCT4, SOX2, NANOG, SSEA1, and SSEA3 on fluorescent immunostaining for stem cell markers. Furthermore, the mRNA expression of canine endogenous OCT4, SOX2, and NANOG significantly increased, confirming the multi-differentiation potential of cells after embryoid and teratoma formation. In this study, iPSCs were successfully generated from canine umbilical cord without the use of a viral vector. Furthermore, canine umbilical cord-derived iPSCs were successfully cultured in a feeder-free manner. This study contributes to the development of veterinary regenerative medicine by using canine iPSCs.

cell biology↗

bioRxiv2022

Degenerate oligonucleotide primer MIG-seq: an effective PCR-based method for high-throughput genotyping

Multiplexed inter-simple sequence repeats genotyping by sequencing (MIG-seq) is an next-generation sequencing library construction method developed for the analysis of DNA in ecology. Although MIG-seq can generate libraries from low-quality DNA, few polymorphisms can be obtained in species with small genomes. In this study, we developed degenerate oligonucleotide primer MIG-seq (dpMIG-seq) as an effective polymorphism discovery method that allows for variation in the number of polymorphisms while retaining the advantages of MIG-seq, including independence from DNA quality. In dpMIG-seq, a proportion of the simple sequence repeats in the primer sequence of the first PCR in MIG-seq was changed to degenerate oligonucleotides to enable annealing to a wider range of sequences. In tests of several crop species other than wheat, the number of loci that could be sequenced using dpMIG-seq with a data volume of 0.3 gigabases (Gb) was increased compared with that sequenced using MIG-seq. In wheat, the number of polymorphisms obtained via dpMIG-seq was higher than that obtained via MIG-seq when a data volume of about [≥]2 Gb was obtained. In dpMIG-seq, different loci could be sequenced by changing the positions of the degenerate oligonucleotides. By applying dpMIG-seq, we constructed a linkage map consisting of 5,142 markers for the rice inter-subspecies F2 population, and we detected quantitative trait loci for heading date in the regions where known heading-related genes were located. Overall, our results show that dpMIG-seq is a useful tool for the genetic analysis of crop species.

genetics↗

bioRxiv2020

Catalytic Promiscuity of Rice 2-Oxoglutarate/Fe(II)-Dependent Dioxygenases Supports Xenobiotic Metabolism

The rice 2-oxoglutarate/Fe(II)-dependent dioxygenase HIS1 mediates the catalytic inactivation of five distinct {beta}-triketone herbicides (bTHs). During a search for potential inhibitors of HIS1, we found that it mediates the hydroxylation of trinexapac-ethyl (TE) in the presence of Fe2+ and 2-oxoglutarate. TE is a plant growth regulator that blocks gibberellin biosynthesis, and we observed that its addition to culture medium induced growth retardation of rice seedlings in a concentration-dependent manner. Similar treatment with hydroxylated TE revealed that hydroxylation greatly attenuated the inhibitory effect of TE on plant growth. Forced expression of HIS1 in a rice his1 mutant also reduced its sensitivity to TE compared with that of the nontransformant. These results indicated that HIS1 metabolizes TE and thereby markedly reduces its ability to slow plant growth. Furthermore, testing of five HIS1-related proteins (HSLs) of rice revealed that OsHSL2 and OsHSL4 also metabolize TE in vitro. HSLs from wheat and barley also showed such activity. In contrast, OsHSL1, which shares the highest amino acid sequence identity with HIS1 and metabolizes the bTH tefuryltrione, did not manifest TE-metabolizing activity. Site-directed mutagenesis of OsHSL1 informed by structural models showed that substitution of three amino acids with the corresponding residues of HIS1 conferred TE-metabolizing activity similar to that of HIS1. Our results thus reveal a catalytic promiscuity of HIS1 and its related enzymes that supports xenobiotic metabolism in plants. One-sentence summaryThe rice 2-oxoglutarate/Fe(II)-dependent dioxygenase HIS1 and related enzymes show broad substrate specificity and mediate metabolism of the growth regulator trinexapac-ethyl as well as of herbicides.

plant biology↗