Biology subjects

Wakita, D.

Publications and source records attributed to Wakita, D..

5 recordsLinked to original sources

bioRxiv2024

The intestinal microbiota contributes to the development of immune-mediated cardiovascular inflammation and vasculitis in mice.

Alterations in the intestinal microbiota contribute to the pathogenesis of various cardiovascular disorders, but how they affect the development of Kawasaki disease (KD), an acute pediatric vasculitis, remains unclear. We report that depleting the gut microbiota reduces the development of cardiovascular inflammation in a murine model mimicking KD vasculitis. The development of cardiovascular lesions was associated with alterations in the intestinal microbiota composition and, notably, a decreased abundance of Akkermansia muciniphila and Faecalibacterium prausnitzii. Oral supplementation with either of these live or pasteurized individual bacteria, or with short-chain fatty acids (SCFAs) produced by them, attenuated cardiovascular inflammation. Treatment with Amuc_1100, the TLR-2 signaling outer membrane protein from A. muciniphila, also decreased the severity of vascular inflammation. This study reveals an underappreciated gut microbiota-cardiovascular inflammation axis in KD vasculitis pathogenesis and identifies specific intestinal commensals that regulate vasculitis in mice by producing metabolites or via extracellular proteins acting on gut barrier function. IN BRIEFIt remains unclear whether changes in the intestinal microbiota composition are involved in the development of cardiovascular lesions associated with Kawasaki disease (KD), an immune-mediated vasculitis. Jena et al. observe alterations in the intestinal microbiota composition of mice developing vasculitis, characterized by reduced A. muciniphila and F. prausnitzii. Oral supplementation with either of these bacteria, live or pasteurized, or with bacteria-produced short-chain fatty acids (SCFAs) or Amuc_1100, the TLR-2 signaling outer membrane protein of A. muciniphila, was sufficient to alleviate the development of cardiovascular lesions in mice by promoting intestinal barrier function. HIGHLIGHTSO_LIAbsence or depletion of the microbiota decreases the severity of vasculitis in a murine model mimicking KD vasculitis. C_LIO_LISupplementation of B. wadsworthia and B. fragilis promotes murine KD vasculitis. C_LIO_LIDecreased abundances of F. prausnitzii and A. muciniphila are associated with the development of cardiovascular lesions in mice. C_LIO_LISupplementation with either live or pasteurized A. muciniphila and F. prausnitzii, or the TLR-2 signaling Amuc_1100, reduces the severity of vasculitis by promoting gut barrier function. C_LI

immunology↗

bioRxiv2019

Arm swapping autograft shows functional equivalency of five arms in sea stars

Extant echinoderms show five-part radial symmetry in typical shape. However, we can find some asymmetry in their details, represented by the madreporite position not at the center, different skeletal arrangement in two of the five rays of sea urchins, and a circular cavity formed by two-end closure. We suspect the existence of any difference in hidden information between the five. In our hypothesis, deep equivalency makes no issue in function even after exchanging the position of rays; otherwise, this autograft causes some trouble in behavior or tissue formation. For this attempt, we firstly developed a method to transplant an arm tip to the counterpart of another arm in the sea star Patiria pectinifera. As a result, seven arms were completely implanted--four into the original positions for a control and three into different positions--with underwater surgery where we sutured with nylon thread and physically prevented nearby tube feet extending. Based on our external and internal observation, each grafted arm (i) gradually recovered movement coordination with the proximal body, (ii) regenerated its lost half as in usual distal regeneration, and (iii) formed no irregular intercalation filling any positional gap at the suture, no matter whether two cut arms were swapped. We here suggest a deep symmetry among the five rays of sea stars not only in morphology but also in physiology, representing an evolutionary strategy that has given equal priority to all the radial directions. Moreover, our methodological notes for grafting a mass of body in sea stars would help echinoderm research involving positional information as well as immunology.

developmental biology↗

bioRxiv2019

Three-dimensional morphological analysis of the dynamic digestive system in the green brittle star

Brittle stars (Echinodermata: Ophiuroidea) digest a great diversity of food in their stomach, which widely lies in the central disk. As for a possible digestive activity, the green brittle star Ophiarachna incrassata (Lamarck, 1816) is known to show a dynamic movement at the disk. This phenomenon would deeply involve the morphological structure of the stomach. However, past anatomical studies have shown the digestive system in two dimensions after wide incision of the body wall anchoring the stomach. This methodology restrains us from understanding how the stomach actually shapes inside a brittle star. We aim to visualize the morphology of brittle stars digestive system in a non-destructive and three-dimensional way, with a comparison between a relaxed specimen and a specimen fixed at the very moment of the disks movement. Employing X-ray micro-computed tomography (micro-CT) and introducing an instant freezing method with cryogenic ethanol, we found the stomach wholly transformed during the movement. We here brought transparency to the in vivo position of gut contents to hint the mechanism and digestive function of the movement. Our outcome spotlights a dynamic digestive process in echinoderms and a widely applicable method for probing into its relation with body structure.

physiology↗

bioRxiv2019

Generalized locomotion of brittle stars with an arbitrary number of arms

Typical brittle stars have five radially symmetrical arms, which coordinate to move their body in a certain direction. However, some species of them show individual difference in the number of arms. We found this trait unique since intact legged animals each own a fixed number of limbs in general. How does a single species manage such different numbers of motile organs to realize adaptive locomotion? We here described four-, five-, six-, and seven-armed locomotion with the aim to generalize a common rule which is flexible with arm numbers in brittle stars. We mechanically stimulated an arm in Ophiactis brachyaspis to analyze escape direction and arm movements. Gathering quantitative indices and employing Bayesian statistical modeling, we figured out an average locomotion: regardless of the total number of arms, a front position emerges at one of the second neighboring arms to a mechanically stimulated arm, while side arms adjacent to the front synchronously work as left and right rowers. We suggest a model where some afferent signal runs either clockwise or anticlockwise along the nerve ring while linearly counting how many arms it passes. This idea would explain how left and right emerges in a radially symmetrical body via a decentralized system.

animal behavior and cognition↗

bioRxiv2018

Five- and Six-armed Brittle Stars Make Different Currents in the Disk

AbstractPhysiological experiments and mathematical models have supported that neuronal activity is crucial for coordinating rhythmic movements of animals. On the other hand, robotics studies have suggested the importance of physical properties made by body structure. However, it remains unclear how morphology affects movement coordination in animals independent of neuronal activity. To begin to understand this issue, this study reports a rhythmic movement in the green brittle star. We found this animal moved five radially symmetric parts in a well-ordered unsynchronized pattern. We explained the coordinated pattern without considering neuronal activity, by building a phenomenological model where internal fluid flows between the body parts. Changing the number of body parts from five to six simulated a synchronized pattern, which is also demonstrated by a rare individual with six symmetric parts. This model suggests the different number in morphology changes the symmetry of the fluid flow, leading to the different synchronization patterns.

physiology↗