Biology subjects

Oishi, S.

Publications and source records attributed to Oishi, S..

4 recordsLinked to original sources

bioRxiv2023

Relationship Between Domain and Function of the Yeast RNase T2, Rny1p, Which Mediates rRNA Degradation upon Starvation

RNase T2 is ubiquitous across diverse organisms, playing essential roles despite its simple enzymatic activity. In Saccharomyces cerevisiae, RNase T2, known as Rny1p, localizes in vacuoles and mediates rRNA degradation during autophagy of ribosomes. In this study, we elucidated novel aspects of ribosome degradation mechanisms and the function of Rny1p. First, we discovered that most ribosomes are degraded by selective autophagy, where Rsa1p is the specific receptor of ribosomes to be degraded. Complex structure prediction suggested that Rsa1p also interacts with Atg8p. Furthermore, we observed that the accumulation of rRNA in vacuoles, due to the lack of Rny1p, leads to a decrease in bulk autophagic activity. This decrease in autophagic activity may explain the inability of Rny1p-deficient strains to adapt to starvation conditions. Second, our structural prediction and biochemical analyses indicate that a C-terminal extension, characteristic in fungal RNase T2 including Rny1p, is not necessary for rRNA degradation but for anchoring to the cell wall. Together with molecular phylogenetic analysis, a species-specific role of RNase T2 conferred by the C-terminal extension is suggested.

molecular biology↗

bioRxiv2023

Mechanisms underpinning morphogenesis of symbiotic organ specialized for hosting indispensable microbial symbiont in stinkbug

Microbial mutualists are pivotal for insect adaptation, which often entails the evolution of elaborate organs for symbiosis. Addressing what mechanisms underpin the development of such organs is of evolutionary interest. Here we investigated the stinkbug Plautia stali whose posterior midgut is transformed into a specialized symbiotic organ. Despite being a simple tube in newborns, it developed numerous crypts in four rows, whose inner cavity hosts a specific bacterial symbiont, during 1st to 2nd nymphal instar. Visualization of dividing cells revealed that active cell proliferation was coincident with the crypt formation, although spatial patterns of the proliferating cells did not reflect the crypt arrangement. Visualization of visceral muscles in the midgut, consisting of circular muscles and longitudinal muscles, uncovered that, strikingly, circular muscles exhibited a characteristic arrangement running between the crypts specifically in the symbiotic organ. Even in early 1st instar when no crypts were seen, two rows of epithelial areas delineated by bifurcated circular muscles were identified. In 2nd instar, crossing muscle fibers newly appeared and connected the adjacent circular muscles, whereby the midgut epithelium was divided into four rows of crypt-to-be areas. The crypt formation proceeded even in aposymbiotic nymphs, uncovering autonomous nature of the crypt development. We propose a mechanistic model of crypt formation wherein the spatial arrangement of muscle fibers and the proliferation of epithelial cells underpin the formation of crypts as midgut evaginations. IMPORTANCEDiverse organisms are associated with microbial mutualists, in which specialized host organs often develop for retaining the microbial partners. In the light of the origin of evolutionary novelties, it is important to understand what mechanisms underpin the elaborate morphogenesis of such symbiotic organs, which must have been shaped through interactions with the microbial symbionts. Using the stinkbug Plautia stali as a model, we demonstrated that visceral muscular patterning and proliferation of intestinal epithelial cells during early nymphal stages are involved in the formation of numerous symbiont-harboring crypts arranged in four rows in the posterior midgut to constitute the symbiotic organ. Strikingly, the crypt formation occurred normally even in symbiont-free nymphs, uncovering that the crypt development proceeds autonomously. These findings suggest that the crypt formation is deeply implemented into the normal development of P. stali, which must reflect the considerably ancient evolutionary origin of the midgut symbiotic organ in stinkbugs.

microbiology↗

bioRxiv2022

NF-κB Decoy ODN-Loaded Poly lactic-co-glycolic Acid Nanospheres Inhibit Alveolar Ridge Resorption

Residual ridge resorption combined with dimensional loss resulting from tooth extraction has a prolonged correlation with early excessive inflammation. Nuclear factor-kappa B (NF-{kappa}B) decoy oligodeoxynucleotide (ODN) is a member of a group of double-stranded DNA capable of downregulating the expression of downstream genes of the NF-{kappa}B pathway. The healing action of its embellished effect combined with poly(lactic-co-glycolic acid) (PLGA) nanospheres on tooth extraction socket still remains unknown. Hence, the aim of this study was to investigate the therapeutic effect of NF-{kappa}B decoy ODN-loaded PLGA nanospheres (PLGA-NfD) transfected into extraction sockets in Wistar/ST rats. Micro-computed tomography and trabecular bone analysis following treatment with PLGA-NfD demonstrated inhibition of vertical alveolar bone loss with increased bone volume, smoother trabecular bone surface, thicker trabecular bone, larger trabecular number and separation, and fewer bone porosities. Histomorphometric and reverse transcription-quantitative polymerase chain reaction analysis revealed reduced tartrate-resistant acid phosphatase-expressing osteoclasts, interleukin-1{beta}, tumor necrosis factor-, receptor activator of NF-{kappa}B ligand, turnover rate and increased transforming growth factor-{beta}1 immunopositive reactions and relative gene expressions. These data demonstrate that local delivery of PLGA-NfD could be used as a substantial suppressor of inflammation during the healing process in a tooth extraction socket, with the potential of accelerated new bone formation.

immunology↗

bioRxiv2021

Systemic regulation of nitrogen acquisition and use in Oryza longistaminata ramets under nitrogen heterogeneity

Oryza longistaminata, a wild rice, vegetatively reproduces and forms a networked clonal colony consisting of ramets connected by rhizomes. Although water, nutrients, and other molecules can be transferred between ramets via the rhizomes, inter-ramet communication in response to spatially heterogeneous nitrogen availability is not well understood. We studied the response of ramet pairs to heterogeneous nitrogen availability by using a split hydroponic system that allowed each ramet root to be exposed to different conditions. Ammonium uptake was compensatively enhanced in the sufficient-side root when roots of the ramet pairs were exposed to ammonium-sufficient and deficient conditions. Comparative transcriptome analysis revealed that a gene regulatory network for effective ammonium assimilation and amino acid biosynthesis was activated in the sufficient-side roots. Allocation of absorbed nitrogen from the nitrogen-sufficient to the deficient ramets was rather limited. Nitrogen was preferentially used for newly growing axillary buds on the sufficient-side ramets. Biosynthesis of trans-zeatin, a cytokinin, was up-regulated in response to the nitrogen supply, but trans-zeatin appears not to target the compensatory regulation. Our results also implied that the O. longistaminata ortholog of OsCEP1 plays a role as a nitrogen-deficient signal in inter-ramet communication, providing compensatory up-regulation of nitrogen assimilatory genes. These results provide insights into the molecular basis for efficient growth strategies of asexually proliferating plants growing in areas where the distribution of ammonium ions is spatially heterogeneous. One sentence summaryOryza longistaminata, a rhizomatous wild rice, systemically regulates ammonium acquisition and use in response to spatially heterogeneous nitrogen availability via inter-ramet communication.

plant biology↗