Some Recent Findings
- Asymmetric pitx2 expression in medaka epithalamus is regulated by nodal signaling through an intronic enhancer "The epithalamic region of fishes shows prominent left-right asymmetries that are executed by Nodal signaling upstream of the asymmetry-determining transcription factor pitx2. Previous reports have identified that nodal controls the left-sided pitx2 expression in the lateral plate mesoderm through an enhancer present in the last intron of this gene. However, whether similar regulation occurs also in the case of epithalamic asymmetry is currently unresolved. Here, we address some of the cis-regulatory information that control asymmetric pitx2 expression in epithalamus by presenting a Tg(pitx2:EGFP) 116-17 transgenic medaka model, which expresses enhanced green fluorescent protein (EGFP) under control of an intronic enhancer. We show that this transgene recapitulates epithalamic expression of the endogenous pitx2 and that it responds to nodal signaling inhibition. Further, we identify that three foxh1-binding sites present in this enhancer modulate expression of the transgene and that the second site is absolutely necessary for the left-sided epithalamic expression while the other two sites may have subtler regulative roles. We provide evidence that left-sided epithalamic pitx2 expression is controlled through an enhancer present in the last intron of this gene and that the regulatory logic underlying asymmetric pitx2 expression is shared between epithalamic and lateral plate mesoderm regions."
- Generation of a transgenic medaka (Oryzias latipes) strain for visualization of nuclear dynamics in early developmental stages "In this study, we verified nuclear transport activity of an artificial nuclear localization signal (aNLS) in medaka fish (Oryzias latipes). We generated a transgenic medaka strain expresses the aNLS tagged enhanced green fluorescent protein (EGFP) driven by a medaka beta-actin promoter. The aNLS-EGFP was accumulated in the nuclei of somatic tissues and yolk nuclei of oocytes, but undetectable in the spermatozoa. The fluorescent signal was observed from immediately after fertilization by a maternal contribution. Furthermore, male and female pronuclei were visualized in fertilized eggs, and nuclear dynamics of pronuclear fusion and subsequent cleavage were captured by time-lapse imaging. In contrast, SV40NLS exhibited no activity of nuclear transport in early embryos. In conclusion, the aNLS possesses a strong nuclear localization activity and is a useful probe for fluorescent observation of the pronuclei and nuclei in early developmental stage of medaka."
- foxl3 is a germ cell-intrinsic factor involved in sperm-egg fate decision in medaka "Sex determination is an essential step in the commitment of a germ cell to a sperm or egg. However, the intrinsic factors that determine the sexual fate of vertebrate germ cells are unknown. Here we show that foxl3, which is expressed in germ cells but not somatic cells in the gonad, is involved in sperm-egg fate decision in medaka fish. Adult XX medaka with disrupted foxl3 developed functional sperm in the expanded germinal epithelium of a histologically functional ovary. In chimeric medaka, mutant germ cells initiated spermatogenesis in female wild-type gonad. These results indicate that a germ cell-intrinsic cue for the sperm-egg fate decision is present in medaka and that spermatogenesis can proceed in a female gonadal environment." ( Forkhead Transcription Factor foxl3 is an ancient duplicated copy of foxl2 | Oocyte Development | Spermatozoa Development)
- YAP is essential for tissue tension to ensure vertebrate 3D body shape "Vertebrates have a unique 3D body shape in which correct tissue and organ shape and alignment are essential for function. For example, vision requires the lens to be centred in the eye cup which must in turn be correctly positioned in the head. Tissue morphogenesis depends on force generation, force transmission through the tissue, and response of tissues and extracellular matrix to force. Although a century ago D'Arcy Thompson postulated that terrestrial animal body shapes are conditioned by gravity, there has been no animal model directly demonstrating how the aforementioned mechano-morphogenetic processes are coordinated to generate a body shape that withstands gravity. Here we report a unique medaka fish (Oryzias latipes) mutant, hirame (hir), which is sensitive to deformation by gravity. hir embryos display a markedly flattened body caused by mutation of YAP, a nuclear executor of Hippo signalling that regulates organ size. We show that actomyosin-mediated tissue tension is reduced in hir embryos, leading to tissue flattening and tissue misalignment, both of which contribute to body flattening. By analysing YAP function in 3D spheroids of human cells, we identify the Rho GTPase activating protein ARHGAP18 as an effector of YAP in controlling tissue tension. Together, these findings reveal a previously unrecognised function of YAP in regulating tissue shape and alignment required for proper 3D body shape." Developmental Signals - Hippo
- The Effects of Rearing Density, Salt Concentration, and Incubation Temperature on Japanese Medaka (Oryzias latipes) Embryo Development "When testing variations in temperature (24°, 28°, and 32°C) and salinity (0.3, 10, 15, and 20 ppt), the onset of heartbeat and onset of retina pigmentation were observed. The original hypotheses were not all supported: as rearing density increased, success of hatch decreased; as salinity increased, only the rate of development for heartbeat increased; as temperature increased, the rate of development for both onset of the heartbeat and retina pigmentation also increased."
|More recent papers
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Search term: Medaka Embryology
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- Osterix-mCherry transgenic medaka for in vivo imaging of bone formation
- Induction of otic structures by canonical Wnt signalling in medaka.
cellular organisms; Eukaryota; Fungi/Metazoa group; Metazoa; Eumetazoa; Bilateria; Coelomata; Deuterostomia; Chordata; Craniata; Vertebrata; Gnathostomata; Teleostomi; Euteleostomi; Actinopterygii; Actinopteri; Neopterygii; Teleostei; Elopocephala; Clupeocephala; Euteleostei; Neognathi; Neoteleostei; Eurypterygii; Ctenosquamata; Acanthomorpha; Euacanthomorpha; Holacanthopterygii; Acanthopterygii; Euacanthopterygii; Percomorpha; Smegmamorpha; Atherinomorpha; Beloniformes; Adrianichthyoidei; Adrianichthyidae; Oryziinae; Oryzias
Adult medaka histology
Development has been characterised by light microscope observation into 39 prehatch stages and 6 posthatch stages.
Prehatch features observed included: number and size of blastomeres, form of the blastoderm, extent of epiboly, central nervous system, number and form of somites, optic and otic, notochord, heart, blood circulation, the size and movement of the body, tail, membranous fin (fin fold), viscera (liver gallbladder, gut tube), spleen and swim (air) bladder.
Posthatch features observed included: fins, scales and secondary sexual characteristics.
||1 h 5 min
||1 h 45 min
||2 h 20 min
||2 h 55 min
||3 h 30 min
||4 h 5 min
||5 h 15 min
||6 h 30 min
||8 h 15 min
||10 h 20 min
||17 h 30 min
||1 day 1 h
||Early neurula (head formation)
||1 day 2 h
||Late neurula (optic bud formation)
||1 day 3 h 30 min
||1 day 7 h 30 min
||1 day 10 h
||6 somite (brain regionalization and otic vesicle formation)
||1 day 14 h
||9 somite (appearance of heart anlage)
||1 day 17 h
||12 somite (formation of tubular heart)
||1 day 20 h
||16 somite (start of heart beating)
||2 days 2 h
||18–19 somite (onset of blood circulation)
||2 days 6 h
||22 somite (development of guanophores and vacuolization of the notochord)
||2 days 10 h
||24 somite (appearance of pectoral fin bud)
||2 days 16 h
||30 somite (onset of retinal pigmentation)
||3 days 2 h
||34 somite (internal ear formation)
||3 days 10 h
||35 somite (blood vessel development)
||3 days 23 h
||Gill blood vessel formation
||4 days 5 h
||Somite completion (formation of pronephros and air bladder)
||4 days 10 h
||at which notochord vacuolization is completed
||5 days 1 h
||Pectoral fin blood circulation
||5 days 12 h
||at which visceral blood vessels form
||Pericardial cavity formation
||Spleen development (differentiation of caudal fin begins)
National BioResource Project Medaka
The National BioResource Project Medaka (NBRP Medaka): an integrated bioresource for biological and biomedical sciences "The Japanese government has supported the development of Medaka Bioresources since 2002. The second term of the Medaka Bioresource Project started in 2007. The National Institute for Basic Biology and Niigata University were selected as the core organizations for this project. More than 400 strains including more than 300 spontaneous and induced mutants, 8 inbred lines, 21 transgenic lines, 20 medaka-related species and 66 wild stock lines of medaka are now being provided to the scientific community and educational non-profit organizations. In addition to these live fish, NBRP Medaka is also able to provide cDNA/EST clones such as full-length cDNA and BAC/fosmid clones covering 90% of the medaka genome."
- Links: National BioResource Project Medaka (NBRP Medaka)
- ↑ 1.0 1.1 Iwamatsu T. (2004). Stages of normal development in the medaka Oryzias latipes. Mech. Dev. , 121, 605-18. PMID: 15210170 DOI.
- ↑ Soukup V, Mrstakova S & Kozmik Z. (2018). Asymmetric pitx2 expression in medaka epithalamus is regulated by nodal signaling through an intronic enhancer. Dev. Genes Evol. , 228, 131-139. PMID: 29663064 DOI.
- ↑ Inoue T, Iida A, Maegawa S, Sehara-Fujisawa A & Kinoshita M. (2016). Generation of a transgenic medaka (Oryzias latipes) strain for visualization of nuclear dynamics in early developmental stages. Dev. Growth Differ. , 58, 679-687. PMID: 27759163 DOI.
- ↑ Nishimura T, Sato T, Yamamoto Y, Watakabe I, Ohkawa Y, Suyama M, Kobayashi S & Tanaka M. (2015). Sex determination. foxl3 is a germ cell-intrinsic factor involved in sperm-egg fate decision in medaka. Science , 349, 328-31. PMID: 26067255 DOI.
- ↑ Porazinski S, Wang H, Asaoka Y, Behrndt M, Miyamoto T, Morita H, Hata S, Sasaki T, Krens SFG, Osada Y, Asaka S, Momoi A, Linton S, Miesfeld JB, Link BA, Senga T, Shimizu N, Nagase H, Matsuura S, Bagby S, Kondoh H, Nishina H, Heisenberg CP & Furutani-Seiki M. (2015). YAP is essential for tissue tension to ensure vertebrate 3D body shape. Nature , 521, 217-221. PMID: 25778702 DOI.
- ↑ Rosemore BJ & Welsh CA. (2012). The effects of rearing density, salt concentration, and incubation temperature on Japanese medaka (Oryzias latipes) embryo development. Zebrafish , 9, 185-90. PMID: 23244689 DOI.
- ↑ Renn J & Winkler C. (2009). Osterix-mCherry transgenic medaka for in vivo imaging of bone formation. Dev. Dyn. , 238, 241-8. PMID: 19097055 DOI.
- ↑ Bajoghli B, Aghaallaei N, Jung G & Czerny T. (2009). Induction of otic structures by canonical Wnt signalling in medaka. Dev. Genes Evol. , 219, 391-8. PMID: 19760182 DOI.
- ↑ PLoS One.
- ↑ Sasado T, Tanaka M, Kobayashi K, Sato T, Sakaizumi M & Naruse K. (2010). The National BioResource Project Medaka (NBRP Medaka): an integrated bioresource for biological and biomedical sciences. Exp. Anim. , 59, 13-23. PMID: 20224166
Liedtke D, Erhard I & Schartl M. (2011). snail gene expression in the medaka, Oryzias latipes. Gene Expr. Patterns , 11, 181-9. PMID: 21094700 DOI.
Shima A & Mitani H. (2004). Medaka as a research organism: past, present and future. Mech. Dev. , 121, 599-604. PMID: 15210169 DOI.
Search Pubmed: Medaka Development