Remodeling of the hyomandibular skeleton and facial nerve positioning during embryonic and postembryonic development of teleost fish.

The vertebrate skeleton changes its shape during development through the activities of chondrocytes, osteoblasts and osteoclasts. Although much is known about the mechanisms for differentiation in these cells, it is less understood how they behave in a region-specific manner to acquire unique bone shapes. To address this question, we investigated the development of the hyomandibular (Hm) system in zebrafish. The Hm originates as cartilage carrying a single foramen (the Hm foramen), through which the facial (VII) nerve passes. We reveal that Schwann cells, which myelinate the VII nerve, regulate rearrangement of the chondrocytes to enlarge the Hm foramen. The Hm cartilage then becomes ossified in the perichondrium, where the marrow chondrocytes are replaced by adipocytes. Then, the bone matrix along the VII nerve is resorbed by osteoclasts, generating a gateway to the bone marrow. Subsequent movement of the VII nerve into the marrow, followed by deposition of new bone matrix, isolates the nerve from the jaw muscle insertion. Genetic ablation of osteoblasts and osteoclasts reveals specific roles of these cells during remodeling processes. Interestingly, the VII nerve relocation does not occur in medaka; instead, bone deposition distinct from those in zebrafish separates the VII nerve from the muscle insertion. Our results define novel mechanisms for skeletal remodeling, by which the bone shapes in a region- and species-specific manner.

Development of the anterior lateral line system through local tissue-tissue interactions in the zebrafish head.

BACKGROUND: The distribution of sensory organs is important for detecting environmental signals efficiently. The mechanosensory receptors of the lateral line system, neuromasts, are stereotypically distributed over the head and body surface of fish, although how neuromasts arise in these predetermined positions during development remains unclear. RESULTS: We investigated the development of the anterior lateral line (ALL) system in zebrafish head. The ALL neuromasts formed in the predetermined positions through proliferation and differentiation of (a) nonmigratory lateral line primordia, (b) migratory primordia, (c) interneuromast cells connecting preexisting neuromasts, and (d) budding primordia. We demonstrated that R-spondin2 (Rspo2), an activator of Wnt/ß-catenin signaling, is required for the development of a particular set of neuromasts associated with hyomandibular cartilage. Further genetic analyses suggested that Rspo2, which emanates from the hyoid mesenchyme, acts on the adjacent neuromast progenitor cells to stimulate their proliferation through activating Wnt/ß-catenin signaling. CONCLUSION: This study has revealed novel mechanisms for neuromast positioning through local tissue-tissue interactions, providing insights into the development and evolution of the vertebrate head.

Epidermal regulation of bone morphogenesis through the development and regeneration of osteoblasts in the zebrafish scale.

Bone is a connective tissue composed of many cell types, including osteoblasts. How bones acquire their unique size and shape during development remains poorly understood. Herein we investigated the molecular and cellular mechanisms of bone morphogenesis in the zebrafish scale by using transgenic lines to enable visualization of specific types of osteoblasts. We demonstrate that the zebrafish scale contains three distinct types of osteoblasts: (i) a monolayer of central osteoblasts along the inner surface of scales; (ii) marginal osteoblasts elongated along the scale edge; and (iii) submarginal osteoblasts located between the central and marginal osteoblast populations. The size of the central osteoblasts increases progressively during development, suggesting that scale growth is mediated primarily by cell growth rather than the recruitment of new osteoblasts. In addition, the total number of central osteoblasts increases in regenerated scales and is correlated with scale size, possibly allowing for the rapid growth of regenerating scales. Moreover, osteoblast proliferation is not detected during regeneration, suggesting that the osteoblasts originate from post-mitotic precursor cells. Sonic hedgehog a (shha) is expressed in the epidermal cells that make contact with the marginal osteoblasts. Pharmacological inhibition of Hedgehog (Hh) signaling during regeneration reduces the number of marginal osteoblasts and interferes with scale growth, indicating that epidermis-derived Shh regulates scale regeneration. Finally, genetic inhibition of Wnt/planar cell polarity (PCP) signaling in the epidermis results in misorientation of scales with regard to the body axis. These results reveal a novel role for the epidermis in the regulation of bone patterning, namely the regeneration of osteoblasts and directional bone growth.

Identification of a neuronal population in the telencephalon essential for fear conditioning in zebrafish.

BACKGROUND: Fear conditioning is a form of learning essential for animal survival and used as a behavioral paradigm to study the mechanisms of learning and memory. In mammals, the amygdala plays a crucial role in fear conditioning. In teleost, the medial zone of the dorsal telencephalon (Dm) has been postulated to be a homolog of the mammalian amygdala by anatomical and ablation studies, showing a role in conditioned avoidance response. However, the neuronal populations required for a conditioned avoidance response via the Dm have not been functionally or genetically defined. RESULTS: We aimed to identify the neuronal population essential for fear conditioning through a genetic approach in zebrafish. First, we performed large-scale gene trap and enhancer trap screens, and created transgenic fish lines that expressed Gal4FF, an engineered version of the Gal4 transcription activator, in specific regions in the brain. We then crossed these Gal4FF-expressing fish with the effector line carrying the botulinum neurotoxin gene downstream of the Gal4 binding sequence UAS, and analyzed the double transgenic fish for active avoidance fear conditioning. We identified 16 transgenic lines with Gal4FF expression in various brain areas showing reduced performance in avoidance responses. Two of them had Gal4 expression in populations of neurons located in subregions of the Dm, which we named 120A-Dm neurons. Inhibition of the 120A-Dm neurons also caused reduced performance in Pavlovian fear conditioning. The 120A-Dm neurons were mostly glutamatergic and had projections to other brain regions, including the hypothalamus and ventral telencephalon. CONCLUSIONS: Herein, we identified a subpopulation of neurons in the zebrafish Dm essential for fear conditioning. We propose that these are functional equivalents of neurons in the mammalian pallial amygdala, mediating the conditioned stimulus-unconditioned stimulus association. Thus, the study establishes a basis for understanding the evolutionary conservation and diversification of functional neural circuits mediating fear conditioning in vertebrates.

Development of the lateral line canal system through a bone remodeling process in zebrafish.

The lateral line system of teleost fish is composed of mechanosensory receptors (neuromasts), comprising superficial receptors and others embedded in canals running under the skin. Canal diameter and size of the canal neuromasts are correlated with increasing body size, thus providing a very simple system to investigate mechanisms underlying the coordination between organ growth and body size. Here, we examine the development of the trunk lateral line canal system in zebrafish. We demonstrated that trunk canals originate from scales through a bone remodeling process, which we suggest is essential for the normal growth of canals and canal neuromasts. Moreover, we found that lateral line cells are required for the formation of canals, suggesting the existence of mutual interactions between the sensory system and surrounding connective tissues.

[Cooperation between a Hospital without Dentists and Local Dental Associations in Oral Management of Cancer Patients].

Severe oral mucositis induced by cancer chemotherapy can cause intolerable pain and increase the risk of systemic infections, necessitating dose reduction and discontinuation of antineoplastic agents. Moreover, this adverse effect may have an impact on patient nutrition and quality of life. An effective and prophylactic intervention should be useful for alleviating this complication. Because Nagoya Memorial Hospital has neither a dentistry nor an oral surgery department, we collaborated with dental associations near the hospital. First, we performed a questionnaire survey on the present status of the members of the local dental associations. The survey showed that 86% of the community dentists were interested in communicating with our hospital. In addition, they agreed to provide us with information on their specialty and status of amenities. In discussion with the community dentists, we decided on fax-based communication for collaboration to improve the quality of oral management in cancer patients. Three seminar series were conducted to share updated information on cancer treatment and enhance communication between the medical doctors and the dentists. Our hospital has registered 129 community dentists and enrolled 81 cancer patients in this medical and dental cooperation initiative.

Interleukin 1 beta promoter polymorphism is associated with keratoconus in a Japanese population.

PURPOSE: Polymorphisms in the interleukin 1 alpha (IL1A) and IL1B gene regions were previously associated with keratoconus in a Korean population. In the present study, we investigated whether the IL1A and IL1B polymorphisms are associated with keratoconus in a Japanese population. METHODS: A total of 169 Japanese patients with keratoconus and 390 Japanese healthy controls were recruited. We genotyped one IL1A single nucleotide polymorphism (SNP; rs2071376) and two IL1B SNPs (rs1143627 and rs16944) to compare the frequencies of alleles, genotypes, and haplotypes between cases and controls. RESULTS: Statistically significant association was observed for rs1143627 (-31 T>C) in the IL1B promoter region; the T allele of rs1143627 was associated with an increased risk of keratoconus (p=0.014, corrected p value [pc]=0.043, odds ratio=1.38). The C allele of rs16944 (-511 C>T) in the IL1B promoter region had a 1.33-fold increased risk of keratoconus, although this increase did not reach statistical significance (p=0.033, pc=0.098). The TT genotype of rs1143627 was weakly associated with an increased risk of keratoconus (p=0.033, pc=0.099, odds ratio=1.52). However, no significant differences were found in the allele and genotype frequencies between the cases and controls for rs2071376 in IL1A. Regarding haplotypic diversity, the haplotype created by the T allele of rs1143627 and C allele of rs16944 was associated with a 1.72-fold increased risk of keratoconus (p=4.0×10(-5), pc=1.6×10(-4)). CONCLUSIONS: Our results replicate associations reported recently in a Korean population. Thus, IL1B may play an important role in the development of keratoconus through genetic polymorphisms.

Impact of Kayumidas© app on subjective symptoms and treatment adherence in allergic Rhinoconjunctivitis: Prospective Single-Arm interventional pilot study.

INTRODUCTION: In the spring of 2021, a physician-supervised application (app) "Kayumidas© - Itchy Eye Alert" was released for allergy sufferers, which implements a function to predict pollen dispersal status for each user based on weather forecasts and notify users of the results. This app provides push notifications of warning levels of itchiness and other symptoms, countermeasures, and the time to use medication. However, no evaluation has been conducted to determine whether the use of app improves compliance with treatment. This study aimed to verify whether the use of a smartphone app is effective in relieving the symptoms of allergic conjunctivitis and rhinitis and how it changes patients' eye drop behavior. METHODS: This was an investigator-initiated, observational, prospective cohort study that was conducted between February 2022 and May 2022. In 62 patients diagnosed with allergic conjunctivitis, the scores of nine subjective eye and nose symptoms (1-4) and eye itchiness (1-7) before and after using the app were compared using a questionnaire. The adherence scores for eye drops (1-4) were also investigated using a questionnaire. RESULTS: The scores for all five ocular subjective symptoms and all four nasal subjective symptoms improved significantly after app use (p < 0.01). Both itching scores (4.1 ± 1.1 vs. 1.6 ± 0.5, p < 0.01) and eye drop compliance scores (2.0 ± 0.7 vs. 3.9 ± 0.3, p < 0.01) improved significantly after app use. CONCLUSION: The use of the Kayumidas© app improved adherence to eye drops and the subjective symptoms of allergic conjunctivitis and rhinitis. Thus, app use effectively improves symptoms by changing behavior and improving self-care awareness regarding treatment in patients with allergic diseases.

Tear Film Osmolarity Measurement in Japanese Dry Eye Patients Using a Handheld Osmolarity System.

We studied the efficacy and safety of a handheld osmolarity measurement system (I-PEN) in Japanese patients with dry eye disease (DED) and non-DED subjects. In this prospective, multicenter study, tear osmolarity was examined using the I-PEN in a total of 122 eyes divided into DED (n = 71) and non-DED (n = 51) groups. Subjective symptoms were assessed using the Dry Eye-Related Quality-of-Life Score (DEQS) questionnaire. Ocular surface condition was evaluated in terms of fluorescein tear breakup time (FBUT) and tear breakup pattern (TBUP), and by fluorescein staining and Schirmer's test. The I-PEN measurements were performed safely in the majority of cases. There was no statistically significant difference in mean tear film osmolarity between the DED and non-DED groups (294.76 ± 16.39 vs. 297.76 ± 16.72 mOsms/L, respectively, p = 0.32). No significant correlations were observed between osmolarity values and DEQS score, FBUT, or the Schirmer score. Osmolarity did not differ among TBUP subgroups. This prospective clinical study found no correlations between the tear film osmolarity values obtained with the I-PEN system and any subjective or objective parameters of DED. Further studies are required to determine the utility of the I-PEN system in other settings.

The Genetic Basis of Morphological Diversity in Domesticated Goldfish.

Although domesticated goldfish strains exhibit highly diversified phenotypes in morphology, the genetic basis underlying these phenotypes is poorly understood. Here, based on analysis of transposable elements in the allotetraploid goldfish genome, we found that its two subgenomes have evolved asymmetrically since a whole-genome duplication event in the ancestor of goldfish and common carp. We conducted whole-genome sequencing of 27 domesticated goldfish strains and wild goldfish. We identified more than 60 million genetic variations and established a population genetic structure of major goldfish strains. Genome-wide association studies and analysis of strain-specific variants revealed genetic loci associated with several goldfish phenotypes, including dorsal fin loss, long-tail, telescope-eye, albinism, and heart-shaped tail. Our results suggest that accumulated mutations in the asymmetrically evolved subgenomes led to generation of diverse phenotypes in the goldfish domestication history. This study is a key resource for understanding the genetic basis of phenotypic diversity among goldfish strains.

A Prospective, Randomized Trial of Two Mucin Secretogogues for the Treatment of Dry Eye Syndrome in Office Workers.

The purpose of the study was to compare the two mucin secretogogues, diquafosol (DQS) and rebamipide (RBM), for the treatment of dry eye syndrome (DES) in office workers. Dry eye patients using computers for >4 h/day were randomly assigned treatment with either DQS or RBM. Main outcomes measures included changes in tear film break-up time (TBUT) and subjective symptoms assessed by the Dry Eye-Related Quality of Life Score (DEQS). The subjects had scheduled examinations at 0 and 4 weeks, and the examinations at 2 and 8 weeks were optional. Changes in keratoconjunctival fluorescein score and a patient satisfaction questionnaire were also recorded. Both groups showed significant improvements in the DEQS scores at 2, 4, and 8 weeks following the initiation of the study. Both groups showed significant increases in the TBUT at 2 and 4 weeks. No significant difference was found between the DQS and RBM groups at any time periods. Patients reported more comfort with the use of DQS compared with the use of RBM. No local or systemic side effects were noted. The results of the present study indicated that both DQS and RBM were effective for the treatment of DES in office workers.

Selenoprotein P-neutralizing antibodies improve insulin secretion and glucose sensitivity in type 2 diabetes mouse models.

Selenoprotein P (SeP) functions as a selenium (Se)-supply protein. SeP is identified as a hepatokine, promoting insulin resistance in type 2 diabetes. Thus, the suppression of Se-supply activity of SeP might improve glucose metabolism. Here, we develop an anti-human SeP monoclonal antibody AE2 as with neutralizing activity against SeP. Administration of AE2 to mice significantly improves glucose intolerance and insulin resistance that are induced by human SeP administration. Furthermore, excess SeP administration significantly decreases pancreas insulin levels and high glucose-induced insulin secretion, which are improved by AE2 administration. Epitope mapping reveals that AE2 recognizes a region of human SeP adjacent to the first histidine-rich region (FHR). A polyclonal antibody against the mouse SeP FHR improves glucose intolerance and insulin secretion in a mouse model of diabetes. This report describes a novel molecular strategy for the development of type 2 diabetes therapeutics targeting SeP.

Production of squalene by squalene synthases and their truncated mutants in Escherichia coli.

Squalene is a precursor of thousands of bioactive triterpenoids and also has industrial value as a lubricant, health-promoting agent, and/or drop-in biofuel. To establish an efficient Escherichia coli-based system for squalene production, we tested two different squalene synthases and their mutants in combination with precursor pathways. By co-expressing a chimeric mevalonate pathway with human or Thermosynechococcus squalene synthase, E. coli accumulated squalene up to 230 mg/L or 55 mg/g-DCW in flask culture. We also determined that a significant truncation of squalene synthase at the C-terminus retains partial cellular activity. The squalene-producing strain described herein represents a convenient platform for gene discovery and the construction of the pathway toward natural and non-natural hopanoids/steroids.

A high-throughput colorimetric screening assay for terpene synthase activity based on substrate consumption.

Terpene synthases catalyze the formation of a variety of terpene chemical structures. Systematic mutagenesis studies have been effective in providing insights into the characteristic and complex mechanisms of C-C bond formations and in exploring the enzymatic potential for inventing new chemical structures. In addition, there is growing demand to increase terpene synthase activity in heterologous hosts, given the maturation of metabolic engineering and host breeding for terpenoid synthesis. We have developed a simple screening method for the cellular activities of terpene synthases by scoring their substrate consumption based on the color loss of the cell harboring carotenoid pathways. We demonstrate that this method can be used to detect activities of various terpene synthase or prenyltransferase genes in a high-throughput manner, irrespective of the product type, enabling the mutation analysis and directed evolution of terpene synthases. We also report the possibility for substrate-specific screening system of terpene synthases by taking advantage of the substrate-size specificity of C30 and C40 carotenoid pathways.

Frizzled3a and Celsr2 function in the neuroepithelium to regulate migration of facial motor neurons in the developing zebrafish hindbrain.

Migration of neurons from their birthplace to their final target area is a crucial step in brain development. Here, we show that expression of the off-limits/frizzled3a (olt/fz3a) and off-road/celsr2 (ord/celsr2) genes in neuroepithelial cells maintains the facial (nVII) motor neurons near the pial surface during their caudal migration in the zebrafish hindbrain. In the absence of olt/fz3a expression in the neuroepithelium, nVII motor neurons extended aberrant radial processes towards the ventricular surface and mismigrated radially to the dorsomedial part of the hindbrain. Our findings reveal a novel role for these genes, distinctive from their already known functions, in the regulation of the planar cell polarity (i.e. preventing integration of differentiated neurons into the neuroepithelial layer). This contrasts markedly with their reported role in reintegration of neuroepithelial daughter cells into the neuroepithelial layer after cell division.

Dual roles of zygotic and maternal Scribble1 in neural migration and convergent extension movements in zebrafish embryos.

In the developing vertebrate hindbrain, the characteristic trajectory of the facial (nVII) motor nerve is generated by caudal migration of the nVII motor neurons. The nVII motor neurons originate in rhombomere (r) 4, and migrate caudally into r6 to form the facial motor nucleus. In this study, using a transgenic zebrafish line that expresses green fluorescent protein (GFP) in the cranial motor neurons, we isolated two novel mutants, designated landlocked (llk) and off-road (ord), which both show highly specific defects in the caudal migration of the nVII motor neurons. We show that the landlocked locus contains the gene scribble1 (scrb1), and that its zygotic expression is required for migration of the nVII motor neurons mainly in a non cell-autonomous manner. Taking advantage of the viability of the llk mutant embryos, we found that maternal expression of scrb1 is required for convergent extension (CE) movements during gastrulation. Furthermore, we show a genetic interaction between scrb1 and trilobite(tri)/strabismus(stbm) in CE. The dual roles of the scrb1 gene in both neuronal migration and CE provide a novel insight into the underlying mechanisms of cell movement in vertebrate development.