Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

To cope with seasonal changes in the environment, organisms adapt their physiology and behavior. Although color perception varies among seasons, the underlying molecular basis and its physiological significance remain unclear. Here we show that dynamic plasticity in phototransduction regulates seasonal changes in color perception in medaka fish. Medaka are active and exhibit clear phototaxis in conditions simulating summer, but remain at the bottom of the tank and fail to exhibit phototaxis in conditions simulating winter. Mate preference tests using virtual fish created with computer graphics demonstrate that medaka are more attracted to orange-red-colored model fish in summer than in winter. Transcriptome analysis of the eye reveals dynamic seasonal changes in the expression of genes encoding photopigments and their downstream pathways. Behavioral analysis of photopigment-null fish shows significant differences from wild type, suggesting that plasticity in color perception is crucial for the emergence of seasonally regulated behaviors.

DOI： 10.1038/s41467-017-00432-8

Web of Science

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

ABSTRACT

In lophiform teleosts, the first dorsal fin has evolved as a specialized structure called the “illicium” equipped with the esca, which is a modified skin flap used to attract small fish for predation. The motor control system of the illicium, however, remained unknown. The present study investigated the innervation of muscles for the illicium and morphology of motoneurons innervating them in the striated frogfish Antennarius striatus. We found that the dorsal ramus of occipital nerve innervates the muscles. Motoneurons for the illicium are present in the dorsolateral zone of ventral horn at the medullo‐spinal boundary level, forming a cluster somewhat distinct from other motoneurons of the ventral horn. Motoneurons for the second to fourth dorsal fins and pectoral fin were located in the ventrolateral and ventromedial zones of ventral horn, respectively, whereas those of the dorsal trunk muscle in the dorsomedial zone of ventral horn. Motoneurons for the first dorsal spine of white‐spotted pygmy filefish were also investigated for species comparison and were found to locate in the ventrolateral zone of ventral horn, similarly to the motoneurons for the second to fourth dorsal fins of the frogfish. These results suggest that motoneurons for the illicium have become segregated from other motoneurons to be situated in an unusual dorsal position for a motoneuron pool of a dorsal fin, in concert with the evolution of specialized “fishing behavior” performed by the illicium.

DOI： 10.1002/cne.25674

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Background

Thyroid hormones (TH) regulate the basal metabolic rate through their receptors THRα and THRβ. TH activates lipid metabolism via THRβ, however, an excess amount of TH can lead to tachycardia, bone loss, and muscle wasting through THRα. In recent years, TH analogs that selectively bind to THRβ have gained attention as new agents for treating dyslipidemia and obesity, which continue to pose major challenges to public health worldwide.

Methods

We developed a TH analog, ZTA-261, by modifying the existing THRβ-selective agonists GC-1 and GC-24. To determine the THRβ-selectivity of ZTA-261, an in vitro radiolabeled TH displacement assay was conducted. ZTA-261 was intraperitoneally injected into a mouse model of high-fat diet-induced obesity, and its effectiveness in reducing body weight and visceral fat, and improving lipid metabolism was assessed. In addition, its toxicity in the liver, heart, and bone was evaluated.

Results

ZTA-261 is more selective towards THRβ than GC-1. Although ZTA-261 is less effective in reducing body weight and visceral fat than GC-1, it is as effective as GC-1 in reducing the levels of serum and liver lipids. These effects are mediated by the same pathway as that of T₃, a natural TH, as evidenced by similar changes in the expression of TH-induced and lipid metabolism-related genes. The bone, cardiac, and hepatotoxicity of ZTA-261 are significantly lower than those of GC-1.

Conclusions

ZTA-261, a highly selective and less toxic THRβ agonist, has the potential to be used as a drug for treating diseases related to lipid metabolism.

DOI： 10.1038/s43856-024-00574-z

Other Link： https://www.nature.com/articles/s43856-024-00574-z

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.cub.2022.09.062

Language：English   Publishing type：Research paper (scientific journal)  

Sleep in Drosophila was defined in the year 2000 by using Drosophila Activity Monitor (DAM) system. But DAM is very small tube space and one fly per tube is very limited to analyze for fly social behavior. To overcome such demerits of DAM system, we developed a novel automated sleep and rhythm analysis system (AutoCircaS) which monitors and records any behaviors like social mating, sleep, and circadian rhythm in flies (Drosophila) and small fishes medaka (Oryzias latipes) in free space using the time-lapse (one frame per 10 sec) imaging. AutoCircaS can detect the caffeine-induced insomnia in flies in light-dark (LD) and constant dark (DD) conditions. Thus, using the AutoCircaS, we discovered that Japanese traditional herbal medicines, KyushinKannouGan-ki (KKG), NouKassei (NK) as well as, and Sansoninto, significantly improved caffeine-induced insomnia in flies. The data suggest that AutoCircaS is useful for sleep analysis of small animals and screening of new sedative-hypnotics from many origins.

DOI： 10.1016/j.gene.2022.146852

PubMed

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/cne.24578

Language：English   Publisher：Academic Press Inc.  

In temperate zones, organisms experience dynamic fluctuations in environment including changes in color. To cope with such seasonal changes in the environment, organisms adapt their physiology and behavior. Although color perception has been believed to be fixed throughout life, there is increasing evidence for the alteration in opsin gene expression induced by environmental stimuli in a number of animals. Very recently, dynamic seasonal plasticity in color perception has been reported in the seasonally breeding medaka fish. Interestingly, seasonal changes in human color perception have also been reported. Therefore, plasticity of color perception, induced by environmental stimuli, might be a common phenomenon across various species.

DOI： 10.1016/j.ygcen.2017.12.010

Scopus

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Mary Ann Liebert Inc  

DOI： 10.1089/thy.2017.0186

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

In this article we review descending neural pathways to the spinal cord in teleosts, compared with mammals. Descending pathways to the spinal cord are crucial in controlling various behaviors in vertebrates. The major difference between teleosts and mammals is the lack of corticospinal (or palliospinal) tracts. Other descending pathways, which originate from the brain stem, are basically identical in teleosts and mammals. This suggests the presence of common systems in the spinal motor control by higher order centers. The homologue of nucleus ruber remained unclear in teleosts until recently, and this review pays special attention to the rubrospinal tract.

DOI： 10.1111/dgd.12355

Web of Science

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：KARGER  

Nucleus ruber is known as an important supraspinal center that controls forelimb movements in tetrapods, and the rubral homologue may serve similar functions in fishes (motor control of pectoral fin). However, two apparently different structures have been identified as 'nucleus ruber' in actinop-terygians. One is nucleus ruber of Goldstein (1905) (NRg), and the other nucleus ruber of Nieuwenhuys and Pouwels (1983) (NRnp). It remains unclear whether one of these nuclei (or perhaps both) is homologous to tetrapod nucleus ruber. To resolve this issue from a phylogenetic point of view, we have investigated the distribution of tegmental neurons retrogradely labeled from the spinal cord in eight actinopterygian species. We also investigated the presence/absence of the two nuclei with Nissl- or Bodian-stained brain section series of an additional 28 actinopterygian species by comparing the morphological features of candidate rubral neurons with those of neurons revealed by the tracer studies. Based on these analyses, the NRg was identified in all actinopterygians investigated in the present study, while the NRnp appears to be absent in basal actinopterygians. The phylogenetic distribution pattern indicates that the NRg is the more likely homologue of nucleus ruber, and the NRnp may be a derived nucleus that emerged during the course of actinopterygian evolution. (C) 2016 S. Karger AG, Basel

DOI： 10.1159/000447442

Web of Science

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