Biology subjects

Matsuo, S.

Publications and source records attributed to Matsuo, S..

7 recordsLinked to original sources

bioRxiv2026

Relationship between gonadosomatic index and spawning-capable status based on gonadal histology in the moonfish Mene maculata

The moonfish Mene maculata (Bloch and Schneider, 1801), the sole extant species of the family Menidae, is widely distributed in the Indo-West Pacific. Although its spawning season has previously been inferred from seasonal variation in the gonadosomatic index (GSI), the histological basis for interpreting GSI as an indicator of spawning-capable status remains limited. Here we describe the gonadal structure of male and female M. maculata and evaluate how GSI and standard length relate to spawning-capable status based on germ cell development. The testis was lobular and exhibited an unrestricted spermatogonial distribution, a structure widely observed among neoteleosts, indicating that the phylogenetic distinctiveness of M. maculata was not associated with a distinctive testicular structure. In the spawning-capable female, oocytes at multiple developmental stages, from primary growth to oocyte maturation, co-occurred within the ovary, indicating asynchronous ovarian development. This finding suggests that M. maculata may be a batch spawner rather than a total spawner as previously inferred. The spawning-capable female had a GSI consistent with previously inferred spawning season estimates. By contrast, histologically examined males were spawning capable at GSI values lower than those previously associated with the inferred spawning season, suggesting that male spawning-capable status may persist beyond the period inferred from elevated GSI alone. This study provides the first histological description of reproductive biology in the phylogenetically distinctive M. maculata and establishes a histological basis for interpreting GSI as a reproductive indicator.

ecology↗

bioRxiv2026

Wnt signaling and tissue tension reconstitute planar cell polarity in vitro

Planar cell polarity (PCP) aligns cells within the plane of a tissue through asymmetric localization of core PCP proteins. In vivo, PCP arises from integration of biochemical signaling and mechanical inputs, making it challendging to reconstruct in vitro. Here we reconstitute PCP in cultured MDCK epithelial cells using Wnt signaling, collective migration, and Prickle3 overexpression. Loss of Vangl1 disrupts reconstituted PCP, directional collective migration, and propagation of ERK traveling waves. Orthogonal manipulation of signaling and mechanics show that tissue tension contributes to establishing a polarity axis, but not its direction, whereas local Wnt input specifies polarity direction. Together, these inputs generate tissue-wide vectorial polarity. This system provides a tractable framework for dissecting how signaling and mechanics are integrated to organize tissues. TeaserWnt signaling and tissue tension reconstitute planar cell polarity in cultured epithelial cells through core-component interdependence and ERK dynamics.

synthetic biology↗

bioRxiv2026

Description of the embryonic development in the convict cichlid (Amatitlania nigrofasciata)

We provide a detailed description of embryonic development in the convict cichlid (Amatitlania nigrofasciata) from fertilization to hatching at 26 {degrees}C, together with a practical staging table anchored to established teleost reference frameworks. Fertilized eggs were obtained by both natural spawning and artificial fertilization. Unfertilized eggs were ovoid and adhesive, surrounded by a chorion and a sticky mucous layer. Early development proceeded, in broad outline, through the teleost sequence of meroblastic discoidal cleavage, blastula, gastrula, segmentation, and organogenesis. The first cleavage occurred at 1.75 hours post-fertilization (hpf), with subsequent cleavages at 30 min intervals, reaching the 64-cell stage at 4.25 hpf. Cleavage up to the 64-cell stage progressed on a timescale broadly comparable to that reported for other cichlids, whereas the interval from the 64-cell stage to early epiboly was relatively short in this species. The high, sphere, and dome stages occurred at 8, 9, and 10 hpf, respectively, with epiboly initiating at the dome stage. At the dome stage, a marginal thickening interpreted as the presumptive embryonic shield became apparent. During early epiboly, the blastoderm showed pronounced spatial heterogeneity: it was consistently thicker and advanced more rapidly on the prospective embryonic axis side, yielding a readily detectable asymmetry. A morphologically distinct embryonic axis became visible at 40-50% epiboly, and epiboly was completed at 28.5 hpf. Notably, somitogenesis began before epiboly completion (first somites at 85-90% epiboly), indicating temporal overlap between late gastrulation and early segmentation. Major organ primordia became apparent during the overlapping segmentation/organogenesis interval, and hatching occurred around 70 hpf. Newly hatched larvae possessed three pairs of adhesive glands. This staging reference enables reproducible developmental sampling and should facilitate future comparative, mechanistic, and experimental work using the convict cichlid.

developmental biology↗

bioRxiv2025

Development of a vehicle for non-invasive oral administration to facilitate behavioral experiments in fish

Pharmacological approaches are increasingly used in diverse fields of fish biology. However, injection-based administration can induce stress or injury, potentially interfering with the natural physiological and behavioral states of the fish. Here, we present a non-invasive vehicle for oral administration of peptide-based compounds. To demonstrate its utility, the oxytocin receptor antagonist atosiban was administered orally using this vehicle. Atosiban was then qualitatively detected in serum by high-performance liquid chromatography. This study provides a proof of concept for an easy-to-use and minimally disruptive tool for various fish experiments.

animal behavior and cognition↗

bioRxiv2024

Explainable AI-guided identification of a novel protein-RNA interactive frame for selective siRNA accumulation in plants

Small interference RNA (siRNA) selectively accumulates and acts in RNA interference (RNAi). Although the components involved in siRNA production have long been the focus of studies to elucidate RNAi processes, the mechanism(s) for selectivity of siRNA (or RNAi effectivity) remains unclear. In a novel approach, we developed a progressive deep learning (DL) framework integrating Transformer and convolutional neural networks to predict the sequences of selectively accumulated siRNAs across various land plant species. These approaches achieved high-accuracy prediction of selectively accumulated 21-nt siRNAs and further identified their key signals, which are positionally and linguistically flexible sequences surrounding the target siRNA. We experimentally validated the contribution of these flexible key signal sequences to siRNA accumulation selectivity using virus-induced gene silencing (VIGS) in Nicotiana benthamiana, and identified RNA-binding proteins that directly recognize the key signal sequences to act for selective siRNA accumulation. These insights provide a novel framework for investigating RNAi mechanisms in plants. One sentence summaryWe discovered a novel mechanism centered on RNA-protein interactions involving the selective accumulation of small-RNAs in plants by applying advanced deep learning frames.

plant biology↗

bioRxiv2024

Facial Coloration as a Social Signal in a Neotropical Cichlid: Testing the Facial Expression Hypothesis

The face is a uniquely distinctive stimulus, encapsulating a wealth of information. Among the myriad of social cues conveyed by the face, emotional signals, known as facial expressions, are paramount not only for humans but also for numerous social animals. The evolution of facial expressions in these animals can also manifest in taxa other than mammals, as suggested by various studies highlighting the socio-ecological benefits of facial expressions. In this study, we elucidated the social function of facial coloration, determined by melanophores, in the neotropical social cichlid Symphysodon aequifasciatus. In this species, facial coloration exhibits instantaneous changes in response to varying social contexts. Through behavioral observations and experimental manipulation, we confirmed that facial coloration in S. aequifasciatus serves to attenuate unnecessary aggressive competition among conspecifics. Furthermore, we observed that the facial area subjected to coloration in this species is innervated by the adenosine triphosphate- and noradrenaline-ergic nervous system. These findings indicated that facial expression in S. aequifasciatus depends on the sympathetic nervous system and has evolved independently of mammalian facial expressions. Our study highlights teleost fishes as valuable animal models for exploring the universality of facial expressions and their underlying cognitive mechanisms in vertebrates.

animal behavior and cognition↗

bioRxiv2022

Quorum sensing-dependent invasion of Ralstonia solanacearum into Fusarium oxysporum chlamydospores

Strains of Ralstonia solanacearum species complex (RSSC), though known as the causative agent of bacterial wilt disease in plants, induce the chlamydospores of many fungi species and invade them through the spores. The lipopeptide ralstonins are the chlamydospore inducers produced by RSSC and are essential for this invasion. However, no mechanistic investigation of this interaction has been conducted. In this study, we report that quorum sensing (QS), which is bacterial cell-cell communication, is important for RSSC to invade the fungus Fusarium oxysporum (Fo). {Delta}phcB, a deletion mutant of QS signal synthase, lost the ability to both produce ralstonins and invade Fo chlamydospores. The QS signal methyl 3-hydroxymyristate rescued these disabilities. In contrast, exogenous ralstonin A, while inducing Fo chlamydospores, failed to rescue the invasive ability. Gene-deletion and -complementation experiments revealed that the QS-dependent production of extracellular polysaccharide (EPS I) is essential for this invasion. The RSSC cells adhered to Fo hyphae and formed biofilms there before inducing chlamydospores. This biofilm formation was not observed in the EPS I- or the ralstonin-deficient mutant. Microscopic analysis showed that RSSC infection resulted in the death of Fo chlamydospores. Altogether, we reported that the RSSC QS system is important for this lethal endoparasitism. Among the factors regulated by the QS system, ralstonins, EPS I, and biofilm are important parasitic factors. SignificanceRSSC strains are Gram-negative bacteria that infect both plants and fungi. The phc QS system of RSSC is important for parasitism in plants because it allows them to invade and increase within the host by causing appropriate system activation at each infection step. In this study, we confirmed not only the importance of ralstonins as Fo chlamydospore inducers, but also that of biofilm formation on the hyphae. In addition to ralstonins, EPS I turned out to be important for biofilm formation. The QS system comprehensively controls the production of these factors in the interaction with Fo. Due to RSSC infection, the cell membranes and organelles of Fo chlamydospores were destroyed, showing that RSSC cells are not endosymbionts but lethal invaders. This result advocates a new QS-dependent mechanism for the process by which a bacterium invades a fungus.

microbiology↗