Biology subjects

Furuya, K.

Publications and source records attributed to Furuya, K..

4 recordsLinked to original sources

bioRxiv2026

Avatar-Induced Postural Responses during a Virtual Full-Body Illusion

Body ownership over an artificial body can alter perceptual and autonomic responses, but its influence on online postural control remains less understood. We investigated whether ownership-related body-avatar correspondence modulates postural responses to an unexpected change in avatar posture. Thirty-six healthy male participants were randomly assigned to an Embodiment condition, in which body-avatar correspondence was maintained, or a Disruption condition, in which the avatar's arm temporarily moved independently of the participant before the critical event. During a standing virtual-reality session with synchronous visuotactile stimulation, the avatar unexpectedly leaned forward. We introduced Avatar-Induced Postural Response (AIPR), an event-related index of anterior-posterior center-of-pressure displacement following the avatar's movement. Ownership-related questionnaire ratings were higher in the Embodiment condition, whereas self-location-related ratings did not differ between conditions. AIPR was greater in the Embodiment condition and was greater than zero only in this condition. AIPR was also positively correlated with skin conductance responses in the Embodiment condition, but was not associated with questionnaire ratings. These findings suggest that an unexpected change in avatar posture can influence the participant's own postural regulation when ownership-related body-avatar correspondence is maintained. AIPR may provide a complementary behavioral index of a postural-control component of avatar embodiment not fully reflected in explicit subjective reports.

neuroscience↗

bioRxiv2025

The nuclear role of methionine adenosyltransferase 2A in immunoglobulin class switch recombination

Methionine adenosyltransferase synthesizes S-adenosylmethionine (SAM), the universal methyl donor. Its ubiquitous isozyme MAT2 is present in the nucleus and regulates gene expression through histone methylation. However, the physiological significance of its nuclear enzymatic activity remains unclear. Here, we investigate the role of nuclear MAT2 in antibody class switch recombination (CSR), a crucial process in adaptive immunity. We established murine B-cell lines expressing either wild-type (WT) or catalytically-inactive (D134A) MAT2A subunits, targeted to the nucleus with nuclear localization signal (NLS). Inhibition of nuclear MAT2 enzymatic activity by expressing NLS-MAT2A(D134A) significantly suppressed CSR from IgM to IgA and reduced intracellular SAM levels. Chromatin immunoprecipitation revealed that MAT2A localized to the IgA switch region. Interestingly, while the expression of germline transcripts was enhanced, the expression of activation-induced cytidine deaminase (AID), an essential enzyme for CSR, was downregulated in NLS-MAT2A(D134A) cells. Our findings demonstrate that the enzymatic activity of MAT2 in the nucleus is indispensable for CSR, likely by ensuring proper AID expression subsequent to germline transcription, thus revealing a critical link between nuclear SAM metabolism and adaptive immunity.

biochemistry↗

bioRxiv2021

Crocosphaera as a major consumer of fixed nitrogen despite its capability of nitrogen fixation

Crocosphaera watsonii (hereafter Crocosphaera) is a key nitrogen (N) fixer in the ocean, but its ability to consume combined N sources is still unclear. Using in situ microcosm incubations with an ecological model, we show that Crocosphaera has high competitive capability both under low and moderately high combined N concentrations. In field incubations, Crocosphaera accounted for the highest consumption of ammonium and nitrate, followed by pico-eukaryotes. The model analysis shows that cells have a high ammonium uptake rate ([~]7 mol N (mol N)-1 d-1 at the maximum), which allows them to compete against pico-eukaryotes and non-diazotrophic cyanobacteria when combined N is sufficiently available. Even when combined N is depleted, their capability of nitrogen fixation allows higher growth rates compared to potential competitors. These results suggest the high fitness of Crocosphaera in combined N limiting, oligotrophic oceans, and thus heightens its potential significance in its ecosystem and in biogeochemical cycling.

microbiology↗

bioRxiv2021

Hypo-osmotic Stress Induces ATP Release via Volume-regulated Anion Channels in Undifferentiated Mammary Cells

The high interstitial ATP concentration in the cancer microenvironment is a major source of adenosine, which acts as a strong immune suppressor. However, the source of ATP release has not been elucidated. We measured the ATP release during hypotonic stress using a real-time ATP luminescence imaging system in primary cultured mammary cells and in breast cell lines. In primary cultured cells, ATP was intermittently released with transient-sharp peaks, while in breast cell lines ATP was released with a slowly rising diffuse pattern. The diffuse ATP release pattern was changed to a transient-sharp pattern by cholera toxin treatment and the reverse change was induced by transforming growth factor (TGF) {beta} treatment. DCPIB, an inhibitor of volume-regulated anion channels (VRACs), only suppressed the diffuse pattern. The inflammatory mediator sphingosine-1-phosphate (S1P) induced a diffuse ATP release pattern isovolumetrically. The knockdown of A isoform of leucine-rich repeat-containing protein 8 (LRRC8A), the essential molecular entity of VRACs, using shRNA suppressed the diffuse pattern. These results suggest that abundantly expressed VRACs are a conduit of ATP release in undifferentiated cells, including cancer cells.

physiology↗