Biology subjects

Masaki, T.

Publications and source records attributed to Masaki, T..

5 recordsLinked to original sources

bioRxiv2026

Effects of culture conditions on morphology and growth of Linderina macrospora (Kickxellomycotina, Kickxellales)

The obscure life histories of many kickxellalean genera remain a bottleneck for comprehensive taxon sampling and phylogenetic reconstruction of the order. While Kickxellales has long been regarded as saprobes inhabiting soil or dung, the discovery of "amphibious fungi" such as Unguispora, which exhibits dimorphic growth between the animal gut and feces, suggests a cryptic gut-dwelling stage within these genera. Given its phylogenetic proximity to Unguispora, ecophysiological traits of Linderina were investigated to evaluate its potential association with the animal gut. Two isolates of L. macrospora were obtained from Japanese soil, representing the first record of this species in Japan. Physiological assays revealed that the optimal temperature for both vegetative growth and sporulation was 25-30 {degrees}C. Furthermore, comparative growth assays on different media demonstrated that sporocladium abundance per sporangiophore is sensitive to nutrient availability, and nutrient-poor media were determined to be the most suitable for evaluating morphological characterization. Under anaerobic, nutrient-rich conditions which are known to induce yeast-like growth in Unguispora, sporangiospores of L. macrospora produce arthrospores. Although marked morphological plasticity was observed during the arthrospore formation, the occurrence of yeast-like unicellular proliferation suggests a potential relationship with the animal gut. Additionally, vegetative growth and sporulation were markedly inhibited by white light exposure; notably, a lethal effect on growth was observed during incubation at 20 {degrees}C, indicating that the natural niche of the species is restricted to light-shielded environments. Our findings will help to elucidate the cryptic life cycles and evolutionary trajectories within Kickxellales.

microbiology↗

bioRxiv2026

Plagl2 unlocks the latent regenerative potential of Müller glia in the adult mouse retina

Muller glia (MG) in the adult mammalian retina have long been recognized as a potential endogenous source for the regeneration of lost retinal neurons. However, existing MG reprogramming strategies yield an incomplete regenerative response by favoring either proliferation or neurogenic differentiation. Here, we show that the zinc-finger transcription factor Plagl2, which has been demonstrated to rejuvenate aged neural stem cells, was sufficient to reprogram adult mouse MG into a progenitor-like state with coupled proliferative and neurogenic competence. Using histology, time-lapse imaging, and single-cell transcriptomics, we found that Plagl2 drove regulated rounds of MG cell cycle re-entry, while N-methyl-D-aspartate-induced retinal injury further promoted the acquisition of neurogenic competence toward inner nuclear layer neuronal identities. These findings identify Plagl2 as a novel rejuvenator of mammalian MG and support the general principle that reprogramming modules can be redeployed across cell types, offering new avenues for unlocking regenerative potential in otherwise non-regenerative tissues.

neuroscience↗

bioRxiv2025

Activation of neurogenesis improves amyloid-β pathology and cognitive function through AMP kinase signaling in Alzheimer's disease model mice

Adult hippocampal neurogenesis declines with aging and in neurological disorders, leading to cognitive impairment. We previously demonstrated that a treatment of inducing Plagl2, a zinc finger transcription factor gene, and antagonizing Dyrk1a, a gene associated with Down syndrome, referred to as iPaD, can functionally rejuvenate aged neural stem cells (NSCs), thereby enhancing neurogenesis and improving cognition in aged mice. Here, we found that NSC-specific iPaD treatment effectively activated neurogenesis, reduced amyloid-{beta} deposition, and improved cognitive function in Alzheimers disease model mice. Transcriptomic analysis revealed widespread significant changes in gene expression in the hippocampus following iPaD treatment. The upregulated genes included those associated with the activation of astrocytes and microglia involved in amyloid-{beta} clearance, while the downregulated genes included several that are upregulated in Alzheimers disease patients, but whose roles in disease progression remain unclear. Among the latter genes, knockdown of Prkag2, a gene encoding protein kinase AMP-activated non-catalytic subunit gamma 2, in the hippocampus most effectively enhanced neurogenesis and reduced amyloid-{beta} accumulation. Notably, both iPaD treatment and Prkag2 knockdown activated AMP-activated protein kinase signaling, thereby upregulating genes involved in autophagy and cellular homeostasis. These results suggest that Prkag2 may represent a promising therapeutic target for neurodegenerative diseases, including Alzheimers disease.

neuroscience↗

bioRxiv2021

Aboveground biomass increments over 26 years (1993-2019) in an old-growth cool-temperate forest in northern Japan

Assessing long-term changes in biomass of old-growth forests is critical in evaluating forest ecosystem functions under a changing climate. Long-term biomass changes are the result of accumulated short-term changes, which can be affected by endogenous processes such as gap filling in small-scale canopy openings. Here, we used 26 years (1993-2019) of repeated tree census data in an old-growth, cool-temperate, deciduous mixed forest that contains three topographic units (riparian, denuded slope, and terrace) in northern Japan to document decadal changes in aboveground biomass (AGB) and their processes in relation to endogenous processes and climatic factors. AGB increased steadily over the 26 years in all topographic units, but different tree species contributed to the increase among the topographic units. AGB gain within each topographic unit exceeded AGB loss via tree mortality in most of the measurement periods despite substantial temporal variation in AGB loss. At the local scale, variations in AGB gain were partially explained by compensating growth of trees around canopy gaps. Climate affected the local-scale AGB gain: the gain was larger in the measurement periods with higher mean temperature during the current summer but smaller in those with higher mean temperature during the previous autumn, synchronously in all topographic units. The decadal climate trends of warming are likely to have contributed to the steady increase in AGB in this old-growth forest.

ecology↗

bioRxiv2020

Timing of fruiting rather than topography determines the direction of vertical seed dispersal by mammals and birds

Vertical seed dispersal toward higher or lower altitudes has been recognized as one of the critical processes for plants to escape from climate change. Studies exploring vertical seed dispersal are scarce, preventing the prediction of future vegetation dynamics. In the present study, we show that the timing of fruiting, rather than topography, determines the direction of vertical seed dispersal by mammals and birds across mountains in central Japan. We found strong uphill seed dispersal of summer fruiting cherry and weak downhill seed dispersal of summer-to-autumn fruiting cherry, irrespective of mountains and animals. The ascent or descent of animals, following the altitudinal gradients in food plant phenology in the temperate zone, was considered to be a driver of the biased seed dispersal. We found that megafauna (i.e., bears) intensively dispersed seeds vertically. The results suggest that the timing of fruiting and megafauna strongly affect whether animal-dispersed temperate plants can maintain their populations under climate change.

ecology↗