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The eyes of squids, octopuses, and cuttlefish are a textbook example for evolutionary convergence, due to their striking similarity to those of vertebrates. For this reason, studies on cephalopod photoreception and vision are of importance for a broader audience. Previous studies showed that genes such as pax6, or certain opsin-encoding genes, are evolutionarily highly conserved and play similar roles during ontogenesis in remotely related bilaterians. In this study, genes that encode photosensitive proteins and Reflectins are identified and characterized. The expression patterns of rhodopsin, xenopsin, retinochrome, and two reflectin genes have been visualized in developing embryos of the pygmy squid Xipholeptos notoides by in situ hybridization experiments. Rhodopsin is not only expressed in the retina of X. notoides but also in the olfactory organ and the dorsal parolfactory vesicles, the latter a cephalopod apomorphy. Both reflectin genes are expressed in the eyes and in the olfactory organ. These findings corroborate previous studies that found opsin genes in the transcriptomes of the eyes and several extraocular tissues of various cephalopods. Expression of rhodopsin, xenopsin, retinochrome, and the two reflectin genes in the olfactory organ is a finding that has not been described so far. In other organisms, it has been shown that Retinochrome and Rhodopsin proteins are obligatorily associated with each other as both molecules rely on each other for Retinal isomerisation. In addition, we demonstrate that retinochrome is expressed in the retina of X. notoides and in the olfactory organ. This study shows numerous new expression patterns for Opsin-encoding genes in organs that have not been associated with photoreception before, suggesting that either Opsins may not only be involved in photoreception or organs such as the olfactory organ are involved in photoreception., (© 2024 The Author(s). Journal of Experimental Zoology Part B: Molecular and Developmental Evolution published by Wiley Periodicals LLC.)

Biodegradable plastics have been commonly developed and applied as an alternative to traditional plastics, which cause environmental plastic pollution. However, biodegradable plastics still present limitations such as stringent degradation conditions and slow degradation rate, and may cause harm to the environment and organisms. Consequently, in this study, zebrafish was used to evaluate the effects of five biodegradable microplastics (MPs), polyglycolic acid (PGA), polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA) and polybutylene adipate terephthalate (PBAT) exposure on the early development, retina morphology, visually-mediated behavior, and thyroid signaling at concentrations of 1 mg/L and 100 mg/L. The results indicated that all MPs induced decreased survival rate, reduced body length, smaller eyes, and smaller heads, affecting the early development of zebrafish larvae. Moreover, the thickness of retinal layers, including inner plexiform layer (IPL), outer nuclear layer (ONL), and retinal ganglion layer (RGL) was decreased, and the expression of key genes related to eye and retinal development was abnormally altered after all MPs exposure. Exposure to PBS and PBAT led to abnormal visually-mediated behavior, indicating likely affected the visual function. All MPs could also cause thyroid system disorders, among which alterations in the thyroid hormone receptors (TRs) genes could affect the retinal development of zebrafish larvae. In summary, biodegradable MPs exhibited eye developmental toxicity and likely impaired the visual function in zebrafish larvae. This provided new evidence for revealing the effects of biodegradable plastics on aquatic organism development and environmental risks to aquatic ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The conserved bazooka (baz/par3) gene acts as a key regulator of asymmetrical cell divisions across the animal kingdom. Associated Par3/Baz-Par6-aPKC protein complexes are also well known for their role in the establishment of apical/basal cell polarity in epithelial cells. Here we define a novel, positive function of Baz/Par3 in the Notch pathway. Using Drosophila wing and eye development, we demonstrate that Baz is required for Notch signaling activity and optimal transcriptional activation of Notch target genes. Baz appears to act independently of aPKC in these contexts, as knockdown of aPKC does not cause Notch loss-of-function phenotypes. Using transgenic Notch constructs, our data positions Baz activity downstream of activating Notch cleavage steps and upstream of Su(H)/CSL transcription factor complex activity on Notch target genes. We demonstrate a biochemical interaction between NICD and Baz, suggesting that Baz is required for NICD activity before NICD binds to Su(H). Taken together, our data define a novel role of the polarity protein Baz/Par3, as a positive and direct regulator of Notch signaling through its interaction with NICD., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

This study aimed to explore how Dab1 functional silencing influences the expression patterns of different connexins in the developing yotari ( yot ) mice eyes as potential determinants of retinogenesis. Using immunofluorescence staining, the protein expression of Dab1, Reelin, and connexin 37, 40, 43, and 45 (Cx37, Cx40, Cx43, and Cx45) in the wild-type (wt) and yot eyes at embryonic days 13.5 and 15.5 (E13.5 and E15.5) were analyzed. Different expression patterns of Cx37 were seen between the wt and yot groups. The highest fluorescence intensity of Cx37 was observed in the yot animals at E15.5. Cx40 had higher expression at the E13.5 when differentiation of retinal layers was still beginning, whereas it decreased at the E15.5 when differentiation was at the advanced stage. Higher expression of Cx43 was found in the yot group at both time points. Cx45 was predominantly expressed at E13.5 in both groups. Our results reveal the altered expression of connexins during retinogenesis in yot mice and their potential involvement in retinal pathology, where they might serve as prospective therapeutic targets.

Understanding the origin of novel morphological traits is a long-standing objective in evolutionary developmental biology. We explored the developmental genetic mechanisms that underpin the formation of a textbook example of evolutionary novelties, the cephalic horns of beetles. Previous work has implicated the gene regulatory networks associated with compound eye and ocellar development in horn formation and suggested that horns and compound eyes may influence each other's sizes. Therefore, we investigated the functional significance of genes central to visual system formation in the initiation, patterning, and size determination of head horns across three horned beetle species. We find that while the downregulation of canonical eye patterning genes reliably reduces or eliminates compound eye formation, it does not alter the position or shape of head horns yet does result in an increase in relative horn length. We discuss the implications of our results for our understanding of the genesis of cephalic horns in particular and evolutionary novelties in general., (© 2024 The Authors. Evolution & Development published by Wiley Periodicals LLC.)

The renewed focus on eye growth in preterm-born children was primarily triggered by Danish cohort studies, including the Copenhagen Project, which focused on children born from 1959-1961. The retinotoxic effects of excessive oxygen on premature neonates had long been clarified and therapeutically adjusted for. Later, ultrasound oculometry and keratometry established that ocular size deficits, linked to development, also occurred in normally developing children, not just frail outliers. This indicated that general catch-up had not been achieved. This paper discusses whether one early segment of eye development does not occur in preterm, and here even in more robust neonates, without later compensation., (© 2024 The Author(s). Acta Paediatrica published by John Wiley & Sons Ltd on behalf of Foundation Acta Paediatrica.)

The optic nerve head (ONH) is a complex structure wherein the axons of the retinal ganglion cells extrude from the eyeball through three openings: 1) the Bruch's membrane opening (BMO) in the retinal layer, 2) the anterior scleral canal opening in the anterior scleral layer, and 3) the lamina cribrosa (LC). Eyeball expansion during growth induces an offset among openings, since the expansion affects the inner retinal and outer scleral layers differently: the posterior polar retinal structure is preserved by the preferential growth in the equatorial region, whereas no such regional difference is observed in the scleral layer. The various modes and extents of eyeball expansion result in diverse directionality and amount of offset among openings, which causes diverse ONH morphology in adults, especially in myopia. In this review, we summarize the ONH changes that occur during myopic axial elongation. These changes were observed prospectively in our previous studies, wherein LC shift and subsequent offset from the BMO center could be predicted by tracing the central retinal vascular trunk position. This offset induces the formation of γ-zone parapapillary atrophy or externally oblique border tissue. As a presumptive site of glaucomatous damage, the LC/BMO offset may render the LC pores in the opposite direction more vulnerable. To support such speculation, we also summarize the relationship between LC/BMO offset and glaucomatous damage. Indeed, LC/BMO offset is not only the cause of diverse ONH morphology in adults, but is also, potentially, an important clinical marker for assessment of glaucoma., Competing Interests: Declaration of competing interest None., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Eye size affects many aspects of visual function, but eyes are costly to grow and maintain. The allometry of eyes can provide insight into this trade-off, but this has mainly been explored in species that have two eyes of equal size. By contrast, animals possessing larger visual systems can exhibit variable eye sizes within individuals. Spiders have up to four pairs of eyes whose sizes vary dramatically, but their ontogenetic, static, and evolutionary allometry has not yet been studied in a comparative context. We report variable dynamics in eye size across 1,098 individuals in 39 species and 8 families, indicating selective pressures and constraints driving the evolution of different eye pairs and lineages. Supplementing our sampling with a recently published phylogenetically comprehensive dataset, we confirmed these findings across more than 400 species; found that ecological factors such as visual hunting, web building, and circadian activity correlate with eye diameter; and identified significant allometric shifts across spider phylogeny using an unbiased approach, many of which coincide with visual hunting strategies. The modular nature of the spider visual system provides additional degrees of freedom and is apparent in the strong correlations between maximum/minimum investment and interocular variance and three key ecological factors. Our analyses suggest an antagonistic relationship between the anterior and posterior eye pairs. These findings shed light on the relationship between spider visual systems and their diverse ecologies and how spiders exploit their modular visual systems to balance selective pressures and optical and energetic constraints., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

It was recently established that the axial power, the refractive power required by the eye for a sharp retinal image in an eye of a certain axial length, and the total refractive power of the eye may both be described by a bi-exponential function as a function of age (Rozema, 2023). Inspired by this result, this work explores whether these bi-exponential functions are able to simulate the various known courses of refractive development described in the literature, such as instant emmetropization, persistent hypermetropia, developing hypermetropia, myopia, instant homeostasis, modulated development, or emmetropizing hypermetropes. Moreover, the equations can be adjusted to match the refractive development of school-age myopia and pseudophakia up to the age of 20 years. All of these courses closely resemble those reported in the previous literature while simultaneously providing estimates for the underlying changes in axial and whole eye power.

The role extracellular matrix (ECM) in multiple events of morphogenesis has been well described, little is known about its specific role in early eye development. One of the first morphogenic events in lens development is placodal thickening, which converts the presumptive lens ectoderm from cuboidal to pseudostratified epithelium. This process occurs in the anterior pre-placodal ectoderm when the optic vesicle approaches the cephalic ectoderm and is regulated by transcription factor Pax6 and secreted BMP4. Since cells and ECM have a dynamic relationship of interdependence and modulation, we hypothesized that the ECM evolves with cell shape changes during lens placode formation. This study investigates changes in optic ECM including both protein distribution deposition, extracellular gelatinase activity and gene expression patterns during early optic development using chicken and mouse models. In particular, the expression of Timp2, a metalloprotease inhibitor, corresponds with a decrease in gelatinase activity within the optic ECM. Furthermore, we demonstrate that optic ECM remodeling depends on BMP signaling in the placode. Together, our findings suggest that the lens placode plays an active role in remodeling the optic ECM during early eye development., (Copyright © 2024 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.)

The Drosophila eye has been an important model to understand principles of differentiation, proliferation, apoptosis and tissue morphogenesis. However, a single cell RNA sequence resource that captures gene expression dynamics from the initiation of differentiation to the specification of different cell types in the larval eye disc is lacking. Here, we report transcriptomic data from 13,000 cells that cover six developmental stages of the larval eye. Our data show cell clusters that correspond to all major cell types present in the eye disc ranging from the initiation of the morphogenetic furrow to the differentiation of each photoreceptor cell type as well as early cone cells. We identify dozens of cell type-specific genes whose function in different aspects of eye development have not been reported. These single cell data will greatly aid research groups studying different aspects of early eye development and will facilitate a deeper understanding of the larval eye as a model system., (© 2024. The Author(s).)

Compound eyes formation in decapod crustaceans occurs after the nauplius stage. However, the key genes and regulatory mechanisms of compound eye development during crustacean embryonic development have not yet been clarified. In this study, RNA-seq was used to investigate the gene expression profiles of Neocaridina denticulata sinensis from nauplius to zoea stage. Based on RNA-seq data analysis, the phototransduction and insect hormone biosynthesis pathways were enriched, and molting-related neuropeptides were highly expressed. There was strong cell proliferation in the embryo prior to compound eye development. The formation of the visual system and the hormonal regulation of hatching were the dominant biological events during compound eye development. The functional analysis of DEGs across all four developmental stages showed that cuticle formation, muscle growth and the establishment of immune system occurred from nauplius to zoea stage. Key genes related to eye development were discovered, including those involved in the determination and differentiation of the eye field, eye-color formation, and visual signal transduction. In conclusion, the results increase the understanding of the molecular mechanism of eye formation in crustacean embryonic stage., (© 2024. The Author(s).)

The Microphthalmia-associated Transcription Factor (MITF) governs numerous cellular and developmental processes. In mice, it promotes specification and differentiation of the retinal pigmented epithelium (RPE), and in humans, some mutations in MITF induce congenital eye malformations. Herein, we explore the function and regulation of Mitf in Drosophila eye development and uncover two roles. We find that knockdown of Mitf results in retinal displacement (RDis), a phenotype associated with abnormal eye formation. Mitf functions in the peripodial epithelium (PE), a retinal support tissue akin to the RPE, to suppress RDis, via the Hippo pathway effector Yorkie (Yki). Yki physically interacts with Mitf and can modify its transcriptional activity in vitro. Severe loss of Mitf, instead, results in the de-repression of retinogenesis in the PE, precluding its development. This activity of Mitf requires the protein phosphatase 2 A holoenzyme STRIPAK-PP2A, but not Yki; Mitf transcriptional activity is potentiated by STRIPAK-PP2A in vitro and in vivo. Knockdown of STRIPAK-PP2A results in cytoplasmic retention of Mitf in vivo and in its decreased stability in vitro, highlighting two potential mechanisms for the control of Mitf function by STRIPAK-PP2A. Thus, Mitf functions in a context-dependent manner as a key determinant of form and fate in the Drosophila eye progenitor epithelium., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier GmbH.. All rights reserved.)

Pax6 is a critical transcription factor involved in the development of the central nervous system. However, in humans, mutations in Pax6 predominantly result in iris deficiency rather than neurological phenotypes. This may be attributed to the distinct functions of Pax6 isoforms, Pax6a and Pax6b. In this study, we investigated the spatial and temporal expression patterns of Pax6 isoforms during different stages of mouse eye development. We observed a strong correlation between Pax6a expression and the neuroretina gene Sox2, while Pax6b showed a high correlation with iris-component genes, including the mesenchymal gene Foxc1. During early patterning from E10.5, Pax6b was expressed in the hinge of the optic cup and neighboring mesenchymal cells, whereas Pax6a was absent in these regions. At E14.5, both Pax6a and Pax6b were expressed in the future iris and ciliary body, coinciding with the integration of mesenchymal cells and Mitf-positive cells in the outer region. From E18.5, Pax6 isoforms exhibited distinct expression patterns as lineage genes became more restricted. To further validate these findings, we utilized ESC-derived eye organoids, which recapitulated the temporal and spatial expression patterns of lineage genes and Pax6 isoforms. Additionally, we found that the spatial expression patterns of Foxc1 and Mitf were impaired in Pax6b-mutant ESC-derived eye organoids. This in vitro eye organoids model suggested the involvement of Pax6b-positive local mesodermal cells in iris development. These results provide valuable insights into the regulatory roles of Pax6 isoforms during iris and neuroretina development and highlight the potential of ESC-derived eye organoids as a tool for studying normal and pathological eye development., Competing Interests: Declaration of competing interest The authors report no disclosures relevant to the manuscript., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Nuclear receptor subfamily 2 group F (Nr2f) proteins are essential for brain development in mice, but little is known about their precise roles and their evolutionary diversification. In the present study, the expression patterns of major nr2f genes (nr2f1a, nr2f1b, and nr2f2) during early brain development were investigated in zebrafish. Comparisons of their expression patterns revealed similar but temporally and spatially distinct patterns after early somite stages in the brain. Frameshift mutations in the three nr2f genes, achieved using the CRISPR/Cas9 method, resulted in a smaller telencephalon and smaller eyes in the nr2f1a mutants; milder forms of those defects were present in the nr2f1b and nr2f2 mutants. Acridine orange staining revealed enhanced cell death in the brain and/or eyes in all nr2f homozygous mutants. The expression of regional markers in the brain did not suggest global defects in brain regionalization; however, shha expression in the preoptic area and hypothalamus, as well as fgf8a expression in the anterior telencephalon, was disturbed in nr2f1a and nr2f1b mutants, potentially leading to a defective telencephalon. Specification of the retina and optic stalk was also significantly affected. The overexpression of nr2f1b by injection of mRNA disrupted the anterior brain at a high dose, and the expression of pax6a in the eyes and fgf8a in the telencephalon at a low dose. The results of these loss- and gain-of-function approaches showed that nr2f genes regulate the development of the telencephalon and eyes in zebrafish embryos., (© 2024 The Authors. Development, Growth & Differentiation published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Developmental Biologists.)

Introduction: Examining the retina represents a non-invasive method to evaluate abnormalities pertaining to the nervous and cardiovascular systems. Evidence indicates that physical activity is a non-pharmacological intervention to enhance the nervous and cardiovascular systems. However, little is unknown about its effects on ocular characteristics in children and adolescents. The purpose of this study was to examine the effects of physical activity interventions on ocular characteristics in children and adolescents., Method: The electronic bases Web of Science, Embase, Cochrane Library, PubMed, SPORTDiscus, CINAHL, and ERIC were searched from inception to May 2023. Incorporated were randomized controlled trials or quasi-experimental designs that had implemented acute or chronic physical activity interventions among children and adolescents to evaluate various eye-related attributes via clinical examinations or surveys. Two authors independently performed the data extraction and risk of bias assessment, utilizing the Physiotherapy Evidence Database checklist., Results: A total of 474 articles were identified, of which eight articles underwent a systematic review, and six were chosen for meta-analysis. Chronic physical activity interventions positively impacted central retinal artery equivalent (CRAE) with a small to moderate effect (SMD = 0.21; 95% CI 0.04 to 0.39, p = 0.034, I 2  = 0%) and central retinal venular equivalent (CRVE) with a small effect (SMD = 0.098; 95% CI 0.08 to 0.11; p = 0.008, I 2  = 0%). Intraocular pressure, kinetic visual acuity, and eye strain also improved significantly after physical activity interventions., Discussion: Participating in chronic physical activity programs appear to impact children and adolescents' eye-related attributes positively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: Treatments are available to slow myopic axial elongation. Understanding normal axial length (AL) distributions will assist clinicians in choosing appropriate treatment for myopia. We report the distribution of AL in Australians of different age groups and refractive errors., Methods: Retrospectively collected spherical equivalent refraction (SER) and AL data of 5938 individuals aged 5 to 89 years from 8 Australian studies were included. Based on the SER, participants were classified as emmetropes, myopes, and hyperopes. Two regression model parameterizations (piece-wise and restricted cubic splines [RCS]) were applied to the cross-sectional data to analyze the association between age and AL. These results were compared with longitudinal data from the Raine Study where the AL was measured at age 20 (baseline) and 28 years., Results: A piece-wise regression model (with 1 knot) showed that myopes had a greater increase in AL before 18 years by 0.119 mm/year (P < 0.001) and after 18 years by 0.011 mm/year (P < 0.001) compared to emmetropes and hyperopes, with the RCS model (with 3 knots) showing similar results. The longitudinal data from the Raine Study revealed that, when compared to emmetropes, only myopes showed a significant change in the AL in young adulthood (by 0.016 mm/year, P < 0.001)., Conclusions: The AL of myopic eyes increases more rapidly in childhood and slightly in early adulthood. Further studies of longitudinal changes in AL, particularly in childhood, are required to guide myopia interventions., Translational Relevance: The axial length of myopic eyes increases rapidly in childhood, and there is a minimal increase in the axial length in non-myopic eyes after 18 years of age.

The eye and brain are composed of elaborately organized tissues, development of which is supported by spatiotemporally precise expression of a number of transcription factors and developmental regulators. Here we report the molecular and genetic characterization of Integrator complex subunit 15 (INTS15). INTS15 was identified in search for the causative gene(s) for an autosomal-dominant eye disease with variable individual manifestation found in a large pedigree. While homozygous Ints15 knockout mice are embryonic lethal, mutant mice lacking a small C-terminal region of Ints15 show ocular malformations similar to the human patients. INTS15 is highly expressed in the eye and brain during embryogenesis and stably interacts with the Integrator complex to support small nuclear RNA 3' end processing. Its knockdown resulted in missplicing of a large number of genes, probably as a secondary consequence, and substantially affected genes associated with eye and brain development. Moreover, studies using human iPS cells-derived neural progenitor cells showed that INTS15 is critical for axonal outgrowth in retinal ganglion cells. This study suggests a new link between general transcription machinery and a highly specific hereditary disease., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The purpose of this study was to examine the effects of age, gender and population origin on human globe and corneal dimensions and to explore the relationships between the dimensions. Human post-mortem eyes were obtained in Hyderabad (n = 223; range, 0-85 years) and Miami (n = 486; range, 6-103 years). The eyes were freed of extraneous tissues and globe antero-posterior length (GAPL), mean globe diameter (MGD) (average of horizontal and vertical), and corneal horizontal (HCD) and vertical (VCD) diameters were measured using digital calipers. The relationships of age, gender and population origin with globe and corneal dimensions and the relationships between the dimensions were assessed by bivalent and multiple regression analyses. Globe and cornea dimensions increase asymptotically with age until around the late teens but do not change thereafter. Bivariate and multivariate regression analyses of the >20-year-old eyes showed that population was significantly correlated with GAPL, MGD, HCD and VCD. Male globes and corneas were larger than those from females, but the difference did not appear to be statistically significant. All Hyderabad dimensions were significantly larger than those from the Miami. Neither GAPL nor MGD were correlated with the corneal dimensions. GAPL was significantly correlated with MGD as was HCD with VCD., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Microglia are the resident immune cells of the central nervous system (CNS). They govern the immunogenicity of the retina, which is considered to be part of the CNS; however, it is not known how microglia develop in the eye. Here, we studied human-induced pluripotent stem cells (hiPSCs) that had been expanded into a self-formed ectodermal autonomous multi-zone (SEAM) of cells that partially mimics human eye development. Our results indicated that microglia-like cells, which have characteristics of yolk-sac-like linage cells, naturally develop in 2D eye-like SEAM organoids, which lack any vascular components. These cells are unique in that they are paired box protein 6 (PAX6)-positive, yet they possess some characteristics of mesoderm. Collectively, the data support the notion of the existence of an isolated, locally developing immune system in the eye, which is independent of the body's vasculature and general immune system., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Ribosomes are essential nanomachines responsible for protein production. Although ribosomes are present in every living cell, ribosome biogenesis dysfunction diseases, called ribosomopathies, impact particular tissues specifically. Here, we evaluate the importance of the box C/D snoRNA-associated ribosomal RNA methyltransferase fibrillarin (Fbl) in the early embryonic development of Xenopus laevis. We report that in developing embryos, the neural plate, neural crest cells (NCCs), and NCC derivatives are rich in fbl transcripts. Fbl knockdown leads to striking morphological defects affecting the eyes and craniofacial skeleton, due to lack of NCC survival caused by massive p53-dependent apoptosis. Fbl is required for efficient pre-rRNA processing and 18S rRNA production, which explains the early developmental defects. Using RiboMethSeq, we systematically reinvestigated ribosomal RNA 2'-O methylation in X. laevis, confirming all 89 previously mapped sites and identifying 15 novel putative positions in 18S and 28S rRNA. Twenty-three positions, including 10 of the new ones, were validated orthogonally by low dNTP primer extension. Bioinformatic screening of the X. laevis transcriptome revealed candidate box C/D snoRNAs for all methylated positions. Mapping of 2'-O methylation at six developmental stages in individual embryos indicated a trend towards reduced methylation at specific positions during development. We conclude that fibrillarin knockdown in early Xenopus embryos causes reduced production of functional ribosomal subunits, thus impairing NCC formation and migration., Competing Interests: The authors have declared that no competing interests exist.

The size of an organ is proportional to the other body parts or the whole body. This relationship is known as allometry. Understanding how allometry is determined is a fundamental question in biology. Here we tested the hypothesis that local insulin-like growth factor (Igf) signaling is critical in regulating organ size and its allometric scaling by organ-specific expression of Igf binding protein (Igfbp). Overexpression of Igfbp2a or 5b in the developing zebrafish eye, heart, and inner ear resulted in a disproportional reduction in their growth relative to the body. Stable transgenic zebrafish with lens-specific Igfbp5b expression selectively reduced adult eye size. The action is Igf-dependent because an Igf-binding deficient Igfbp5b mutant had no effect. Targeted expression of a dominant-negative Igf1 receptor (dnIgf1r) in the lens caused a similar reduction in relative eye growth. Furthermore, co-expression of IGF-1 with an Igfbp restored the eye size. Finally, co-expression of a constitutively active form of Akt with Igfbp or dnIgf1r restored the relative eye growth. These data suggest that local Igf availability and Igf signaling activity are critical determinants of organ size and allometric scaling in zebrafish., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Purpose: Peripheral refraction and accommodation are intrinsic factors that were once hypothesized to trigger myopia but are now controversial. Previously, home nearwork environment (i.e., extrinsic factor) was reported to be associated with myopia progression. In this study, we aimed to evaluate the potential interaction between extrinsic and intrinsic factors with juvenile refractive development., Methods: Nearwork environmental parameters were measured for 50 children (aged 9.3 ± 1.2 years), including net amount and dispersion of defocus. Refraction was measured at near distances and in central field (±30° horizontal) at 3m. The relative peripheral refraction (RPRE) was obtained and presented in a vectoral approach. The linear regression coefficient was extracted (mAcc) from the accommodative stimulus-response curve. RPRE was quadratically regressed against field eccentricity, and the first coefficients (aM, aJ0, aP90, and aP180) were extracted. Relationships between RPRE, baseline accommodation, and 1-year myopia progression (∆M), controlled for the nearwork environment, were evaluated., Results: Coefficients of RPRE were independent of ∆M. However, additional nearwork environmental parameters significantly improved the variance in ∆M explained by aM and aP180 (P < 0.03). The relationship between intrinsic factor and ∆M was stronger when the extrinsic risk was low (P ≤ 0.01), whereas the relationship was abolished when extrinsic risk was high. For mAcc, it also significantly improved the variance in ∆M explained by nearwork environmental parameters., Conclusions: The interaction between extrinsic (environment) and intrinsic (RPRE and accommodation) factors is speculated to contribute to juvenile myopia progression. Our findings may also explain the inconsistencies of such intrinsic factors in the literature.

The morphogenesis of the vertebrate eye consists of a complex choreography of cell movements, tightly coupled to axial regionalization and cell type specification processes. Disturbances in these events can lead to developmental defects and blindness. Here, we have deciphered the sequence of defective events leading to coloboma in the embryonic eye of the blind cavefish of the species Astyanax mexicanus. Using comparative live imaging on targeted enhancer-trap Zic1:hsp70:GFP reporter lines of both the normal, river-dwelling morph and the cave morph of the species, we identified defects in migratory cell behaviours during evagination that participate in the reduced optic vesicle size in cavefish, without proliferation defect. Further, impaired optic cup invagination shifts the relative position of the lens and contributes to coloboma in cavefish. Based on these results, we propose a developmental scenario to explain the cavefish phenotype and discuss developmental constraints to morphological evolution. The cavefish eye appears as an outstanding natural mutant model to study molecular and cellular processes involved in optic region morphogenesis., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)

Postnatal ocular growth is regulated by a vision-dependent mechanism that acts to minimize refractive error through coordinated growth of the ocular tissues. Of great interest is the identification of the chemical signals that control visually guided ocular growth. Here, we provide evidence that the pro-inflammatory cytokine, interleukin-6 (IL-6), may play a pivotal role in the control of ocular growth using a chicken model of myopia. Microarray, real-time RT-qPCR, and ELISA analyses identified IL-6 upregulation in the choroids of chick eyes under two visual conditions that introduce myopic defocus and slow the rate of ocular elongation (recovery from induced myopia and compensation for positive lenses). Intraocular administration of atropine, an agent known to slow ocular elongation, also resulted in an increase in choroidal IL-6 gene expression. Nitric oxide appears to directly or indirectly upregulate choroidal IL-6 gene expression, as administration of the non-specific nitric oxide synthase inhibitor, L-NAME, inhibited choroidal IL-6 gene expression, and application of a nitric oxide donor stimulated IL-6 gene and protein expression in isolated chick choroids. Considering the pleiotropic nature of IL-6 and its involvement in many biological processes, these results suggest that IL-6 may mediate many aspects of the choroidal response in the control of ocular growth., Competing Interests: JS, EM No competing interests declared, (© 2021, Summers and Martinez.)

Because the normal operation of the eye depends on sensitive morphogenetic processes for its eventual shape, developmental flaws can lead to wide-ranging ocular defects. However, the physical processes and mechanisms governing ocular morphogenesis are not well understood. Here, using analytical theory and nonlinear shell finite-element simulations, we show, for optic vesicles experiencing matrix-constrained growth, that elastic instabilities govern the optic cup morphogenesis. By capturing the stress amplification owing to mass increase during growth, we show that the morphogenesis is driven by two elastic instabilities analogous to the snap through in spherical shells, where the second instability is sensitive to the optic cup geometry. In particular, if the optic vesicle is too slender, it will buckle and break axisymmetry, thus, preventing normal development. Our results shed light on the morphogenetic mechanisms governing the formation of a functional biological system and the role of elastic instabilities in the shape selection of soft biological structures.

Lutein is a dietary carotenoid preferentially accumulated in the eye and the brain in early life and throughout the life span. Lutein accumulation in areas of high metabolism and oxidative stress such as the eye and the brain suggest a unique role of this ingredient during the development and maturation of these organs of common embryological origin. Lutein is naturally provided to the developing baby via the cord blood, breast milk and then infant diet. The presence of this carotenoid depends on fruit and vegetable intakes and its bioavailability is higher in breastmilk. This paper aims to review the anatomical development of the eye and the brain, explore the presence and selective deposition of lutein in these organs during pregnancy and infancy and, based on its functional characteristics, present the latest available research on the beneficial role of lutein in the pediatric population. The potential effects of lutein in ameliorating conditions associated with increase oxidative stress such as in prematurity will be also addressed. Since consumption of lutein rich foods falls short of government guidelines and in most region of the world infant formulas lack this bioactive, dietary recommendations for pregnant and breastfeeding women and their child can help to bridge the gap.

Myopia (short-sightedness), usually caused by excessive elongation of the eye during development, has reached epidemic proportions worldwide. In animal systems including the chicken model, several treatments have been shown to inhibit ocular elongation and experimental myopia. Although diverse in their apparent mechanism of action, each one leads to a reduction in the rate of ocular growth. We hypothesize that a defined set of retinal molecular changes may underlie growth inhibition, irrespective of the treatment agent used. Accordingly, across five well-established but diverse methods of inhibiting myopia, significant overlap is seen in the retinal transcriptome profile (transcript levels and alternative splicing events) in chicks when analyzed by RNA-seq. Within the two major pathway networks enriched during growth inhibition, that of cell signaling and circadian entrainment, transcription factors form the largest functional grouping. Importantly, a large percentage of those genes forming the defined retinal response are downstream targets of the transcription factor EGR1 which itself shows a universal response to all five growth-inhibitory treatments. This supports EGR1's previously implicated role in ocular growth regulation. Finally, by contrasting our data with human linkage and GWAS studies on refractive error, we confirm the applicability of our study to the human condition. Together, these findings suggest that a universal set of transcriptome changes, which sit within a well-defined retinal network that cannot be bypassed, is fundamental to growth regulation, thus paving a way for designing novel targets for myopia therapies., (© 2021 The Authors. The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Background/aims: Both eyes of one individual share the same environment and genes. We examined interocular differences in biometry to determine the potential role of other factors in refractive development., Methods: 362 subjects (6-7 years) from the Northern Ireland Childhood Errors of Refraction study were studied. Cycloplegic autorefraction was measured with a Shin-Nippon open-field autorefractor. Axial length and corneal curvature were measured with a Zeiss IOLMaster., Results: 257 subjects had an interocular difference of <0.50 D (ISO group) and 105 (29%) a difference of ≥0.50 D (ANISO group). Twenty-five subjects (6.9%) had anisometropia ≥1.00 D and 9 (2.5%) had anisometropia ≥1.50 D. The two groups, ISO and ANISO, showed different refractive distributions (p=0.001) with the ISO group showing a nearly Gaussian distribution and the ANISO group showing positive skew, a hyperopic shift and a bi-Gaussian distribution. A marker of emmetropisation is the poor correlation between refraction and corneal curvature seen in older children. There was no significant correlation between refraction and corneal curvature of each eye in the ISO group (r=0.09, p=0.19), but these parameters were significantly correlated in the ANISO group (r=0.28, p=0.004)., Conclusion: In young children, small degrees of anisometropia (≥0.5 D) are associated with impaired emmetropisation. This suggests that anisometropia is a marker for poorly regulated eye growth, indicating that, in addition to environmental and genetic influences on eye growth, stochastic processes contribute to refractive outcomes., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

The forkhead transcription factor FOXE3 is critical for vertebrate eye development. Recessive and dominant variants cause human ocular disease but the full range of phenotypes and mechanisms of action for the two classes of variants are unknown. We identified FOXE3 variants in individuals with congenital eye malformations and carried out in vitro functional analysis on selected alleles. Sixteen new recessive and dominant families, including six novel variants, were identified. Analysis of new and previously reported genetic and clinical data demonstrated a broad phenotypic range with an overlap between recessive and dominant disease. Most families with recessive alleles, composed of truncating and forkhead-domain missense variants, had severe corneal opacity (90%; sclerocornea in 47%), aphakia (83%) and microphthalmia (80%), but some had milder features including isolated cataract. The phenotype was most variable for recessive missense variants, suggesting that the functional consequences may be highly dependent on the type of amino acid substitution and its position. When assessed, aniridia or iris hypoplasia were noted in 89% and optic nerve anomalies in 60% of recessive cases, indicating that these defects are also common and may be underrecognized. In dominant pedigrees, caused by extension variants, normal eye size (96%), cataracts (99%) and variable anterior segment anomalies were seen in most, but some individuals had microphthalmia, aphakia or sclerocornea, more typical of recessive disease. Functional studies identified variable effects on the protein stability, DNA binding, nuclear localization and transcriptional activity for recessive FOXE3 variants, whereas dominant alleles showed severe impairment in all areas and dominant-negative characteristics., (© The Author(s) 2021. Published by Oxford University Press.)

Visual opsins are proteins expressed by retinal photoreceptors that capture light to begin the process of phototransduction. In vertebrates, the two types of photoreceptors (rods and cones) express one or multiple opsins and are distributed in variable patterns across the retina. Some cones form opsin retinal gradients, as in the mouse, whereas others form more demarcated opsin domains, as in the lattice-like mosaic retinas of teleost fishes. Reduced rod opsin (rh1) expression in mouse, zebrafish, and African clawed frog results in lack of photoreceptor outer segments (i.e., the cilium that houses the opsins) and, in the case of the mouse, to retinal degeneration. The effects of diminished cone opsin expression have only been studied in the mouse where knockout of the short-wavelength sensitive 1 (sws1) opsin leads to ventral retinal cones lacking outer segments, but no retinal degeneration. Here we show that, following CRISPR/Cas9 injections that targeted knockout of the sws1 opsin in rainbow trout, fish with diminished sws1 opsin expression exhibited a variety of developmental defects including head and eye malformations, underdeveloped outer retina, mislocalized opsin expression, cone degeneration, and mosaic irregularity. All photoreceptor types were affected even though sws1 is only expressed in the single cones of wild fish. Our results reveal unprecedented developmental defects associated with diminished cone opsin expression and suggest that visual opsin genes are involved in regulatory processes that precede photoreceptor differentiation., (© 2021 Wiley Periodicals LLC.)

It is well known that human crystalline lens shape, dimensions and optical properties change throughout life and influence whole eye refraction. However, it is not clear if lens properties are associated with other ocular parameters. The purpose of the present study was to investigate the relationship of corneal and external globe dimensions with adult lens diameter (LD), lens thickness (LT) and lens power (LP) in order to determine if external factors influence lens properties. Postmortem human eyes (n = 66, age = 20-78 years) were obtained from the Ramayamma International Eye Bank, Hyderabad, India. Globe antero-posterior length (GAPL) and mean (average of horizontal and vertical) diameters of cornea (MCD) and globe (MGD) were measured using digital calipers. Eyes were dissected to produce ocular structures that contain the lens maintained in its accommodating framework, including intact zonules, ciliary body and sections of sclera. Specimens were mounted in a mechanical lens stretching system. LD, LT and LP were measured using high magnification retro-illumination photography, slit illumination photography and Scheiner principle-based optical system respectively in the unstretched (accommodated) state. Relationships between external globe and corneal dimensions and LD, LT or LP were assessed by multiple regression analysis. Age (0.012 ± 0.003 mm/year; p<0.001) and GAPL (0.185 ± 0.045 mm/mm; p<0.001) were significant (p<0.0001) predictors of LD. After adjusting for age-related increases, LD appears to be positively correlated with GAPL. Age (0.010 ± 0.004 mm/year; p = 0.009) and GAPL (-0.143 ± 0.060 mm/mm; p = 0.02) were significant (p = 0.001) predictors of LT. After adjusting for the age-related increase, LT appears to be negatively correlated with GAPL. Only age was a significant predictor of LP (-0.26 ± 0.04 D/year; p<0.001). The results suggest that, apart from aging, lens diameter and thickness are dependent on the anteroposterior length of the eye globe. Lens power is not influenced by globe dimensions., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The Eyes Absent (EYA) transactivator-phosphatase proteins are important contributors to cell-fate determination processes and to the development of multiple organs. The transcriptional regulatory activity as well as the protein tyrosine phosphatase activities of the EYA proteins can independently contribute to proliferation, differentiation, morphogenesis and tissue homeostasis in different contexts. Aberrant EYA levels or activity are associated with numerous syndromic and non-syndromic developmental disorders, as well as cancers. Commensurate with the multiplicity of biochemical activities carried out by the EYA proteins, they impact upon a range of cellular signaling pathways. Here, we provide a broad overview of the roles played by EYA proteins in development, and highlight the molecular signaling pathways known to be linked with EYA-associated organ development and developmental disorders., (© 2021 The Author(s).)

The Hippo pathway is an important regulator of organ growth and cell fate. In the R8 photoreceptor cells of the Drosophila melanogaster eye, the Hippo pathway controls the fate choice between one of two subtypes that express either the blue light-sensitive Rhodopsin 5 (Hippo inactive R8 subtype) or the green light-sensitive Rhodopsin 6 (Hippo active R8 subtype). The degree to which the mechanism of Hippo signal transduction and the proteins that mediate it are conserved in organ growth and R8 cell fate choice is currently unclear. Here, we identify Crumbs and the apical spectrin cytoskeleton as regulators of R8 cell fate. By contrast, other proteins that influence Hippo-dependent organ growth, such as the basolateral spectrin cytoskeleton and Ajuba, are dispensable for the R8 cell fate choice. Surprisingly, Crumbs promotes the Rhodopsin 5 cell fate, which is driven by Yorkie, rather than the Rhodopsin 6 cell fate, which is driven by Warts and the Hippo pathway, which contrasts with its impact on Hippo activity in organ growth. Furthermore, neither the apical spectrin cytoskeleton nor Crumbs appear to regulate the Hippo pathway through mechanisms that have been observed in growing organs. Together, these results show that only a subset of Hippo pathway proteins regulate the R8 binary cell fate decision and that aspects of Hippo signalling differ between growing organs and post-mitotic R8 cells., Competing Interests: The authors have declared that no competing interests exist.

In broadband light, longitudinal chromatic aberration (LCA) provides emmetropization signals from both wavelength defocus and the resulting chromatic cues. Indoor illuminants vary in their spectral output, potentially limiting the signals from LCA. Our aim is to investigate the effect that artificial illuminants with different spectral outputs have on chick emmetropization with and without low temporal frequency modulation. In Experiment 1, two-week-old chicks were exposed to 0.2 Hz, square-wave luminance modulation for 3 days. There were 4 spectral conditions: LED strips that simulated General Electric (GE) LED "Soft" (n = 13), GE LED "Daylight" (n = 12), a novel "Equal" condition (n = 12), and a novel "High S" condition (n = 10). These conditions were all tested at a mean level of 985 lux. In Experiment 2, the effect of intensity on the "Equal" condition was tested at two other light levels (70 lux: n = 10; 680 lux: n = 7). In Experiment 3, the effect of temporal modulation on the "Equal" condition was tested by comparing the 0.2 Hz condition with 0 Hz (steady). Significant differences were found in axial growth across lighting conditions. At 985 lux, birds exposed to the "Equal" condition showed a greater reduction in axial growth (both p < 0.01) and a greater hyperopic shift compared to "Soft" and "Daylight" (both p < 0.01). The "High S" birds experienced more axial growth compared to "Equal" (p < 0.01) but less than in "Soft" and "Daylight" (p < 0.01). Axial changes in "Equal" were only observed at 985 lux with 0.2 Hz temporal modulation, and not with lower light levels or steady light. We conclude that axial growth and refraction were dependent on the lighting condition in a manner predicted by wavelength defocus signals arising from LCA., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The ability to respond to light has profoundly shaped life. Animals with eyes overwhelmingly rely on their visual circuits for mediating light-induced coordinated movements. Building on previously reported behaviors, we report the discovery of an organized, eye-independent (extraocular), body-wide photosensory framework that allows even a head-removed animal to move like an intact animal. Despite possessing sensitive cerebral eyes and a centralized brain that controls most behaviors, head-removed planarians show acute, coordinated ultraviolet-A (UV-A) aversive phototaxis. We find this eye-brain-independent phototaxis is mediated by two noncanonical rhabdomeric opsins, the first known function for this newly classified opsin-clade. We uncover a unique array of dual-opsin-expressing photoreceptor cells that line the periphery of animal body, are proximal to a body-wide nerve net, and mediate UV-A phototaxis by engaging multiple modes of locomotion. Unlike embryonically developing cerebral eyes that are functional when animals hatch, the body-wide photosensory array matures postembryonically in "adult-like animals." Notably, apart from head-removed phototaxis, the body-wide, extraocular sensory organization also impacts physiology of intact animals. Low-dose UV-A, but not visible light (ocular-stimulus), is able to arouse intact worms that have naturally cycled to an inactive/rest-like state. This wavelength selective, low-light arousal of resting animals is noncanonical-opsin dependent but eye independent. Our discovery of an autonomous, multifunctional, late-maturing, organized body-wide photosensory system establishes a paradigm in sensory biology and evolution of light sensing., Competing Interests: The authors declare no competing interest.

In the face, symmetry is established when bilateral streams of neural crest cells leave the neural tube at the same time, follow identical migration routes and then give rise to the facial prominences. However, developmental instability exists, particularly surrounding the steps of lip fusion. The causes of instability are unknown but inability to cope with developmental fluctuations are a likely cause of congenital malformations, such as non-syndromic orofacial clefts. Here, we tracked cell movements over time in the frontonasal mass, which forms the facial midline and participates in lip fusion, using live-cell imaging of chick embryos. Our mathematical examination of cell velocity vectors uncovered temporal fluctuations in several parameters, including order/disorder, symmetry/asymmetry and divergence/convergence. We found that treatment with a Rho GTPase inhibitor completely disrupted the temporal fluctuations in all measures and blocked morphogenesis. Thus, we discovered that genetic control of symmetry extends to mesenchymal cell movements and that these movements are of the type that could be perturbed in asymmetrical malformations, such as non-syndromic cleft lip. This article has an associated 'The people behind the papers' interview., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)

During the development of the vertebrate nervous systems, genetic programs assemble an immature circuit that is subsequently refined by neuronal activity evoked by external stimuli. However, prior to sensory experience, the intrinsic property of the developing nervous system also triggers correlated network-level neuronal activity, with retinal waves in the developing vertebrate retina being the best documented example. Spontaneous activity has also been found in the visual system of Drosophila Here, we compare the spontaneous activity of the developing visual system between mammalian and Drosophila and suggest that Drosophila is an emerging model for mechanistic and functional studies of correlated spontaneous activity., (© 2021 Choi et al.; Published by Cold Spring Harbor Laboratory Press.)

Myopia results from an excessive axial growth of the eye, causing abnormal projection of remote images in front of the retina. Without adequate interventions, myopia is forecasted to affect 50% of the world population by 2050. Exposure to outdoor light plays a critical role in preventing myopia in children, possibly through the brightness and blue-shifted spectral composition of sunlight, which lacks in artificial indoor lighting. Here, we evaluated the impact of moderate levels of ambient standard white (SW: 233.1 lux, 3900 K) and blue-enriched white (BEW: 223.8 lux, 9700 K) lights on ocular growth and metabolomics in a chicken-model of form-deprivation myopia. Compared to SW light, BEW light decreased aberrant ocular axial elongation and accelerated recovery from form-deprivation. Furthermore, the metabolomic profiles in the vitreous and retinas of recovering form-deprived eyes were distinct from control eyes and were dependent on the spectral content of ambient light. For instance, exposure to BEW light was associated with deep lipid remodeling and metabolic changes related to energy production, cell proliferation, collagen turnover and nitric oxide metabolism. This study provides new insight on light-dependent modulations in ocular growth and metabolomics. If replicable in humans, our findings open new potential avenues for spectrally-tailored light-therapy strategies for myopia.

Animals regulate a variety of aspects of physiology according to environmental light conditions via nonvisual opsins such as melanopsin. In order to study photic regulation of fish physiology, expression changes of the genes for melanopsin (opn4xa and opn4xb) and effects of light on them were examined in juvenile grass puffer Takifugu alboplumbeus using quantitative real-time PCR. In the brain of juvenile fish, no significant diurnal nor circadian changes were observed in opn4x mRNA levels. On the other hand, in the eyes, the mRNA level of opn4xa showed a significant diurnal rhythm with a peak at Zeitgeber time (ZT) 4, while no apparent circadian changes were observed. The mRNA level of opn4xb in the eyes showed a diurnal change similar to that of opn4xa, while it showed a significant circadian change. Furthermore, continuous exposure to light during a subjective night significantly increased the mRNA levels of opn4xa in the eyes at ZT24, suggesting that light induces gene expression of opn4xa in the eyes and that the induction occurs only during the night-day transition period. These results suggest that Opn4xa and Opn4xb play differential roles in the eyes of juvenile grass puffer to mediate the physiological effects of environmental light information.

Precise regulation of ocular size is a critical determinant of normal visual acuity. Although it is generally accepted that ocular growth relies on a cascade of signaling events transmitted from the retina to the sclera, the factors and mechanism(s) involved are poorly understood. Recent studies have highlighted the importance of the retinal secreted serine protease PRSS56 and transmembrane glycoprotein MFRP, a factor predominantly expressed in the retinal pigment epithelium (RPE), in ocular size determination. Mutations in PRSS56 and MFRP constitute a major cause of nanophthalmos, a condition characterized by severe reduction in ocular axial length/extreme hyperopia. Interestingly, common variants of these genes have been implicated in myopia, a condition associated with ocular elongation. Consistent with these findings, mice with loss of function mutation in PRSS56 or MFRP exhibit a reduction in ocular axial length. However, the molecular network and cellular processes involved in PRSS56- and MFRP-mediated ocular axial growth remain elusive. Here, we show that Adamts19 expression is significantly upregulated in the retina of mice lacking either Prss56 or Mfrp. Importantly, using genetic mouse models, we demonstrate that while ADAMTS19 is not required for ocular growth during normal development, its inactivation exacerbates ocular axial length reduction in Prss56 and Mfrp mutant mice. These results suggest that the upregulation of retinal Adamts19 is part of an adaptive molecular response to counteract impaired ocular growth. Using a complementary genetic approach, we show that loss of PRSS56 or MFRP function prevents excessive ocular axial growth in a mouse model of early-onset myopia caused by a null mutation in Irbp, thus, demonstrating that PRSS56 and MFRP are also required for pathological ocular elongation. Collectively, our findings provide new insights into the molecular network involved in ocular axial growth and support a role for molecular crosstalk between the retina and RPE involved in refractive development., Competing Interests: The authors have declared that no competing interests exist.

The optic vesicle in the developing embryonic eye contains a multitude of neuroepithelial progenitors that subsequently differentiate into functionally distinct domains of the optic cup, such as the neural retina, pigment epithelium, and optic stalk. To investigate cell-type diversity across early optic vesicles before regionalization of the optic cup, we performed single-cell RNA-sequencing (scRNA-seq) using 7989 cells from the presumptive eye area in mouse embryos at the 12-26-somite stages at five developmental time points. We demonstrated the presence of seven optic vesicle populations. Moreover, the four populations of retinal progenitor cells could be classified according to their stage-dependent time point, and these cells exhibited altered expression of several structural and metabolic key genes, such as Col9a1 and Ckb, just before regionalization of the optic cup. From these data, we provide the first report on stage-dependent transcriptional profiles during initial retinal specification at single-cell resolution and highlight the unexpected developmental heterogeneity of the murine optic vesicle structure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Developmental regulation of the vertebrate visual system has been a focus of investigation for generations as understanding this critical time period has direct implications on our understanding of congenital blinding disease. The majority of studies to date have focused on transcriptional regulation mediated by morphogen gradients and signaling pathways. However, recent studies of post translational regulation during ocular development have shed light on the role of the ubiquitin proteasome system (UPS). This rather ubiquitous yet highly diverse system is well known for regulating protein function and localization as well as stability via targeting for degradation by the 26S proteasome. Work from many model organisms has recently identified UPS activity during various milestones of ocular development including retinal morphogenesis, retinal ganglion cell function as well as photoreceptor homeostasis. In particular work from flies and zebrafish has highlighted the role of the E3 ligase enzyme family, Seven in Absentia Homologue (Siah) during these events. In this review, we summarize the current understanding of UPS activity during Drosophila and vertebrate ocular development, with a major focus on recent findings correlating Siah E3 ligase activity with two major developmental stages of vertebrate ocular development, retinal morphogenesis and photoreceptor specification and survival., (© 2021 The Author(s).)

H6 family homeobox 1 (HMX1) regulates multiple aspects of craniofacial development as it is widely expressed in the eye, peripheral ganglia and branchial arches. Mutations in HMX1 are linked to an ocular defect termed Oculo-auricular syndrome of Schorderet-Munier-Franceschetti (MIM #612109). We identified UHRF1 as a target of HMX1 during development. UHRF1 and its partner proteins actively regulate chromatin modifications and cellular proliferation. Luciferase assays and in situ hybridization analyses showed that HMX1 exerts a transcriptional inhibitory effect on UHRF1 and a modification of its expression pattern. Overexpression of hmx1 in hsp70-hmx1 zebrafish increased uhrf1 expression in the cranial region, while mutations in the hmx1 dimerization domains reduced uhrf1 expression. Moreover, the expression level of uhrf1 and its partner dnmt1 was increased in the eye field in response to hmx1 overexpression. These results indicate that hmx1 regulates uhrf1 expression and, potentially through regulating the expression of factors involved in DNA methylation, contribute to the development of the craniofacial region of zebrafish., Competing Interests: The authors have declared that no competing interests exist.

C-mannosylation is a modification of tryptophan residues with a single mannose and can affect protein folding, secretion, and/or function. To date, only a few proteins have been demonstrated to be C-mannosylated, and studies that globally assess protein C-mannosylation are scarce. To interrogate the C-mannosylome of human induced pluripotent stem cells, we compared the secretomes of CRISPR-Cas9 mutants lacking either the C-mannosyltransferase DPY19L1 or DPY19L3 to WT human induced pluripotent stem cells using MS-based quantitative proteomics. The secretion of numerous proteins was reduced in these mutants, including that of A Disintegrin And Metalloproteinase with ThromboSpondin Motifs 16 (ADAMTS16), an extracellular protease that was previously reported to be essential for optic fissure fusion in zebrafish eye development. To test the functional relevance of this observation, we targeted dpy19l1 or dpy19l3 in embryos of the Japanese rice fish medaka (Oryzias latipes) by CRISPR-Cas9. We observed that targeting of dpy19l3 partially caused defects in optic fissure fusion, called coloboma. We further showed in a cellular model that DPY19L1 and DPY19L3 mediate C-mannosylation of a recombinantly expressed thrombospondin type 1 repeat of ADAMTS16 and thereby support its secretion. Taken together, our findings imply that DPY19L3-mediated C-mannosylation is involved in eye development by assisting secretion of the extracellular protease ADAMTS16., Competing Interests: Conflict of interest The authors declare no competing interests., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: To assess the validity of and compare applanation and rebound tonometry readings of intraocular pressure in alert normal chicks from ages 3 to 45 days., Methods: Intraocular pressures (IOPs) were measured weekly in awake White Leghorn chicks, from ages 3-45 days (n = 22-30 per age group), with both applanation Tono-Pen and rebound TonoLab tonometers. Three repeated measurements on individual eyes were used to derive variance data for both instruments at each age. Calibration curves were also derived for each instrument and each age, weekly from ages 10-45 days (n = 3-4 per age group), from in situ manometry data collected over IOP settings of 0 to 100 mmHg in 5 mmHg steps in cannulated eyes., Results: The TonoLab showed less within measurement variability, but more variability with age, than the Tono-Pen. The coefficient of variation ranged from 3.8-8.3% for the TonoLab, compared to 11.0-19.7% for the Tono-Pen across all ages. For the youngest, 3 day-old chicks, mean IOPs recorded with the Tono-Pen and TonoLab were not significantly different (17.0 ± 5.6 and 15.2 ± 3.7 mmHg, respectively, P = .27). However, with increasing age, IOP readings significantly increased for the TonoLab ( P < .001), whereas Tono-Pen readings did not. Compared to manometry settings, the Tono-Pen tended to underestimate IOPs while the TonoLab overestimated IOPs over the range 20-60 mmHg, saturating thereafter; there were also age-dependent differences for the TonoLab., Conclusions: Both the Tono-Pen and TonoLab gave IOP readings that differed from manometry settings in normal young chicks over some or all of the ages tested. These results reinforce the importance of calibrating clinical tonometers in animal studies involving IOP as a key variable.

Vertebrate eyes share the same general organization, though species have evolved morphological and functional adaptations to diverse environments. Cave-adapted animals are characterized by a variety of features including eye reduction, loss of body pigmentation, and enhanced non-visual sensory systems. Species that live in perpetual darkness have also evolved sensory mechanisms that are independent of light stimuli. The subterranean catfish Phreatobius cisternarum lives in the Amazonian phreatic zone and displays a diversity of morphological features that are similar to those observed in cavefish and appear to be adaptations to life in the dark. Here we combine histological and transcriptome analyses to characterize sensory adaptations of P. cisternarum to the subterranean environment. Histological analysis showed that the vestigial eyes of P. cisternarum contain a rudimentary lens. Transcriptome analysis revealed a repertoire of eleven visual and non-visual opsins and the expression of 36 genes involved in lens development and maintenance. In contrast to other cavefish species, such as Astyanax mexicanus , Phreatichthys andruzzii, Sinocyclocheilus anophthalmus and Sinocyclocheilus microphthalmus , DASPEI neuromast staining patterns did not show an increase in the number of sensory hair cells. Our work reveals unique adaptations in the visual system of P. cisternarum to underground habitats and helps to shed light into troglomorphic attributes of subterranean animals.

Understanding how complex organ systems are assembled from simple embryonic tissues is a major challenge. Across the animal kingdom a great diversity of visual organs are initiated by a 'master control gene' called Pax6 , which is both necessary and sufficient for eye development. Yet precisely how Pax6 achieves this deeply homologous function is poorly understood. Using the chick as a model organism, we show that vertebrate Pax6 interacts with a pair of morphogen-coding genes, Tgfb2 and Fst , to form a putative Turing network, which we have computationally modelled. Computer simulations suggest that this gene network is sufficient to spontaneously polarise the developing retina, establishing the first organisational axis of the eye and prefiguring its further development. Our findings reveal how retinal self-organisation may be initiated independently of the highly ordered tissue interactions that help to assemble the eye in vivo These results help to explain how stem cell aggregates spontaneously self-organise into functional eye-cups in vitro We anticipate these findings will help to underpin retinal organoid technology, which holds much promise as a platform for disease modelling, drug development and regenerative therapies., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2020. Published by The Company of Biologists Ltd.)

Our understanding of cancer-specific metabolic changes is currently unclear. In recent years, the fruit fly Drosophila melanogaster with its powerful genetic tools has become an attractive model for studying both tumor autonomous and the systemic processes resulting from the tumor growth. Here we investigated the effect of tumorigenesis on the modulation of lipid droplets (LDs) in the larval fat bodies (mammalian equivalent of adipose tissue). We have overexpressed Notch signaling alone or in combination with the developmental regulator Myocyte enhancer factor 2 (Mef2) using wing-specific and eye-specific drivers, quantified the size of LDs in the fat body of the different tumor bearing larvae, and estimated the expression of genes associated with lipolysis and lipogenesis. We have found that hyperplastic and neoplastic tumor induced by overexpression of Notch and co-expression of Notch and Mef2 respectively triggers impaired lipid metabolism marked by increased size of fat body LDs. The impaired lipid metabolism in tumor carrying larvae is linked to the altered expression of genes that participate in lipolysis and lipogenesis. These findings reveal modulation of LDs as one of the host's specific response upon tumor initiation. This information could potentially uncover mechanisms for designing innovative approaches to modulate cancer growth., (Copyright © 2020 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

In oviparous fish larvae, the mouth-open period is a crucial physiological and metabolic switch period. To explore the molecular mechanisms involved in metabolism during this stage in Coilia nasus larvae, we performed next generation RNA-seq technology to assemble de novo a transcriptome and analyzed differential expressed genes (DEGs). In our study, 307,825 unigenes were generated. 154 genes significantly increased, and 144 genes were significantly inhibited during the mouth-open period. Metabolism-related DEGs were classified into retinol metabolism, purine metabolism, and lipid metabolism, and they were altered during this stage. These activated metabolism-related genes would contribute to eye development, cell cycle, and lipid storage. Moreover, some genes related to eye development, cell cycle, and lipid storage were detected by RT-qPCR. These results indicated that retinol metabolism, purine metabolism, and lipid metabolism were improved, and they would contribute to eye development, cell cycle, and lipid storage during the mouth-open period in C. nasus larvae. These results would contribute to comprehending the physiological and metabolic switches during the mouth-open period, and provide the theoretical basis for breeding., (Copyright © 2020. Published by Elsevier Inc.)