Biology subjects

Ota, K. G.

Publications and source records attributed to Ota, K. G..

3 recordsLinked to original sources

bioRxiv2025

Histological divergence underlying globular body shapes in ornamental goldfish

Body shape diversity in vertebrates reflects a complex interplay between functional demands, environmental constraints, and internal developmental mechanisms. Various environments have promoted diverse morphological adaptations not only under natural but also domesticated conditions. One of the most remarkable examples of artificially induced morphology is found in the domesticated ornamental goldfish (Carassius auratus), which has diversified into numerous strains with strikingly different body shapes through prolonged human selection. In this study, we compared the body shapes of representative goldfish strains: the single-tail common goldfish (wild-type), Ryukin, Oranda, Pearl scale, and Ranchu. Our analysis revealed that the Ryukin and Pearl scale strains exhibit significantly greater body circularity in dorsal view compared to the other strains. Further anatomical and histological analyses showed that Pearl scale goldfish possess a thicker lateral body wall along with increased adipose tissue accumulation and reduced muscle fiber density, unlike Ryukin goldfish. These findings suggest that similar globular body shapes in different goldfish strains have arisen through distinct developmental pathways, exemplifying morphological convergence accompanied by histological divergence. We further discuss adipose accumulation in Pearl scale goldfish in relation to natural examples, providing insight into how function, morphology, and tissue organization may be interlinked in the evolution of globular body shapes.

zoology↗

bioRxiv2024

Tracing of the developmental origin of the caudal fin muscle in zebrafish

Teleost species possess complex caudal musculoskeletal systems. While mid-trunk muscles exhibit simple segmental patterns, several caudal skeletal muscles display intricate orientations in their muscle fibers. Due to this distinctive morphology, both early and recent researchers have studied the structure and development of the caudal musculoskeletal system. However, the early developmental origin of the cell populations within the caudal muscle system remains largely unknown. In this study, we performed lineage tracing of caudal muscle primordia in zebrafish using a transgenic line expressing EGFP in somite derivatives following tamoxifen induction. This approach allowed us to observe the specific cell populations that contribute to caudal muscle tissue formation at the early larval stage. By monitoring the growth of these labeled cells from the early larval stage, we identified the origins of muscle fibers in caudal fin muscles unique to teleosts, such as the adductor caudalis and flexor caudalis. Our findings provide descriptions that aid in understanding how fish-specialized caudal muscle structures were formed through the modification of developmental processes during evolution.

developmental biology↗

bioRxiv2023

On the independent irritability of goldfish eggs and embryos -- a living communication on the rhythmic yolk contractions in goldfish

Rhythms play an important role in the precise spatiotemporal regulation of biological processes during development and patterning of embryos. We here investigate the rhythmic contractions of the yolk during early development of the goldfish Carassius auratus. We quantify these contractions and record robust and persistent rhythmic yolk movements that are not seen in closely-related species (common carp Cyprinus carpio and zebrafish Danio rerio). We report that yolk contractions are an intrinsic emergent property of the egg, i.e. goldfish eggs are independently irritable / excitable. These contractions do not require sperm entry / fertilization nor cell division, and they notably emerge at a precise time -- suggesting that goldfish eggs are able to measure elapsed time from what we infer to be egg activation. We further show that these rhythmic contractions persist even in yolk in isolation. As the yolk itself is known to confer critical cues for early dorsoventral (DV) patterning of teleost embryos, we hypothesize that its contractions in goldfish may influence the patterning process of this species. Indeed, we find that embryos of the naturally more ventralized twin-tail goldfish strain Oranda display altered yolk contraction dynamics (i.e. faster contractions). We also present that the period of yolk contractions is independent of ChdS, a key gene involved in DV pattening and linked to the twin-tail phenotype, but is instead a trait that is maternal in origin. We aim to uncover whether the yolk contractions happening during early development of domesticated goldfish are the licensing process which permit the emergence of novel patterning phenotypes naturally-observed in this species (e.g. twin-tail and dorsal-finless strains) and which instead have not been found among closely-related species (e.g. common carp) whose yolks do not contract. This manuscript is here published as a living communication (as described in Gnaiger (2021)). The authors intend to share findings when they are available, encourage feedback and discussion, and invite knowledge exchange and collaboration.

developmental biology↗