Biology subjects

Sanchez, P. G. L.

Publications and source records attributed to Sanchez, P. G. L..

7 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

Evolutionary Insights into Muscle Fiber Distribution in the Twin Tails of Ornamental Goldfish

Twin-tail ornamental goldfish have a bifurcated caudal fin with a morphology that is extremely diverged from the conventional body plan of the vertebrates. Here, we investigate the muscu-loskeletal histology of this bifurcated caudal fin. From some of the investigated twin-tail goldfish, we found a twin-tail goldfish specific muscle (hereafter referred to as the "medial caudal muscle") between left and right bifurcated caudal fin skeletons. Our immunohistochemical analyses revealed that the medial caudal muscle showed laterally biased distribution patterns of the slow and fast muscle fibers. Similar distribution patterns were also commonly observed in several deep muscles of wild-type goldfish as well as zebrafish, suggesting that these muscle fiber distribution patterns are formed by the same molecular developmental mechanisms even though their morphologies are highly diverged. These findings provide empirical evidence to consider how the histological features of a newly emerged morphology are influenced by selective pressures and pre-existing developmental mechanisms.

developmental biology↗

bioRxiv2024

The Wnt/β-catenin/TCF/Sp5/Zic4 gene network that regulates head organizer activity in Hydra is differentially regulated in epidermis and gastrodermis

In Hydra, head formation depends on Wnt/{beta}-catenin signaling, which positively regulates Sp5 and Zic4, with Sp5 limiting Wnt3/{beta}-catenin expression and Zic4 triggering tentacle formation. Using transgenic lines in which the HySp5 promoter drives eGFP expression in the epidermis or gastrodermis, we show that in intact animals, epidermal HySp5:GFP is expressed strongly apically and weakly along the body column, while gastrodermal HySp5:GFP is also maximally expressed apically but absent from the oral region, and remains high along the upper body column. During apical regeneration, gastrodermal HySp5:GFP appears early and diffusely, epidermal HySp5:GFP later. Upon alsterpaullone treatment, apical HySp5:GFP expression is shifted to the body column where epidermal HySp5:GFP transiently forms ectopic circular figures. After {beta}-catenin(RNAi), only epidermal HySp5:GFP is down-regulated, while pseudo-bud structures expressing gastrodermal HySp5:GFP develop. Sp5(RNAi) highlights the negative autoregulation of Sp5 in epidermis, involving direct binding of Sp5 to its own promoter as observed in human HEK293T cells. In these cells, HyZic4, which can interact with huTCF1, regulates Wnt3 negatively and Sp5 positively. This differential regulation of the Wnt/{beta}-catenin/TCF/Sp5/Zic4 network in epidermis and gastrodermis highlights distinct architectures and patterning roles in the hypostome, tentacle and body column, as well as distinct regulations in homeostatic and developmental organizers.

developmental biology↗

bioRxiv2024

Glycolysis-Wnt signaling axis tunes developmental timing of embryo segmentation

The question of how metabolism impacts development is seeing a renaissance [1, 2]. How metabolism exerts instructive signaling functions is one of the central issues that need to be resolved. We tackled this question in the context of mouse embryonic axis segmentation. Previous studies have shown that changes in central carbon metabolism impact Wnt signaling [3-6] and the period of the segmentation clock [7], which controls the timing of axis segmentation. Here, we reveal that glycolysis tunes the segmentation clock period in an anti-correlated manner: higher glycolytic flux slows down the clock, and vice versa. Transcriptome and gene regulatory network analyses identified Wnt signaling and specifically the transcription factor Tcf7l2, previously associated with increased risk for diabetes [8, 9], as potential mechanisms underlying flux-dependent control of the clock period. Critically, we show that deletion of the Wnt antagonist Dkk1 rescued the slow segmentation clock phenotype caused by increased glycolysis, demonstrating that glycolysis instructs Wnt signaling to control the clock period. In addition, we demonstrate metabolic entrainment of the segmentation clock: periodic changes in the levels of glucose or glycolytic sentinel metabolite fructose 1,6-bisphosphate (FBP) synchronize signaling oscillations. Notably, periodic FBP pulses first entrained Wnt signaling oscillations and subsequently Notch signaling oscillations. We hence conclude that metabolic entrainment has an immediate, specific effect on Wnt signaling. Combined, our work identifies a glycolysis-FBP-Wnt signaling axis that tunes developmental timing, highlighting the instructive signaling role of metabolism in embryonic development.

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↗

bioRxiv2021

The transcription factor Zic4 acts as a transdifferentiation switch

The molecular mechanisms that maintain cell identities and prevent transdifferentiation remain mysterious. Interestingly, both dedifferentiation and transdifferentiation are transiently reshuffled during regeneration. Therefore, organisms that regenerate readily offer a fruitful paradigm to investigate the regulation of cell fate stability. Here, we used Hydra as a model system and show that Zic4 silencing is sufficient to induce transdifferentiation of tentacle into foot cells. We identified a Wnt-controlled Gene Regulatory Network that controls a transcriptional switch of cell identity. Furthermore, we show that this switch also controls the re-entry into the cell cycle. Our data indicate that maintenance of cell fate by a Wnt-controlled GRN is a key mechanism during both homeostasis and regeneration. One-Sentence SummaryA Wnt-controlled GRN controls fate maintenance in Hydra.

developmental biology↗

bioRxiv2021

Arnold tongue entrainment reveals dynamicalprinciples of the embryonic segmentation clock

Living systems exhibit an unmatched complexity, due to countless, entangled interactions across scales. Here we aim to understand a complex system, i.e. segmentation timing in mouse embryos, without a reference to these detailed interactions. To this end, we develop a coarse-grained approach, in which theory guides the experimental identification of the segmentation clock entrainment responses. We demonstrate period- and phase-locking of the segmentation clock across a wide range of entrainment parameters, including higher-order coupling. These quantifications allow to derive the phase response curve (PRC) and Arnold tongues of the segmentation clock, revealing its essential dynamical properties. Our results indicate that the somite segmentation clock has characteristics reminiscent of a highly non-linear oscillator close to an infinite period bifurcation and suggests the presence of long-term feedbacks. Combined, this coarse-grained theoretical-experimental approach reveals how we can derive simple, essential features of a highly complex dynamical system, providing precise experimental control over the pace and rhythm of the somite segmentation clock.

developmental biology↗