Karyotype evolution and relationship of a small ricefish, Oryzias minutillus, from Thailand.

Magtoon, Wichian; Uwa, Hiroshi

doi:10.2183/pjab.61.157

Cited by 15 publications

(15 citation statements)

References 1 publication

(1 reference statement)

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“…Chromosomes were prepared using primary culture cells from the whole embryos of the d-rR strain (Magtoon and Uwa, 1985;Uwa and Ojima, 1981). Three whole embryos (stage 33-35, by Iwamatsu, 1994) were sterilized by immersion in 1 % sodium hypochlorite, PBS(-), 70 % ethanol, and PBS(-), for a few seconds each.…”

Section: Chromosome Preparation and Fishmentioning

confidence: 99%

Identification of the sex chromosomes of the medaka, Oryzias latipes, by fluorescence in situ hybridization

Matsuda

Matsuda²,

Hamaguchi³

et al. 1998

Cytogenet Genome Res

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In the medaka, Oryzias latipes, which does not have cytologically recognizable sex chromosomes, the sex is genetically determined and the mechanism of sex determination (XX/XY) can be revealed by genetic crosses using a particular pigment gene. In a previous study, we isolated a sex-linked DNA marker (SL1) using the genomic differences between inbred strains of medaka. In the present paper, we further isolated another sex-linked clone (pHO5.110). The pHO5.110-related sequences were tightly linked to sex in O. latipes. We designated the locus of the pHO5.110-related sequence on sex chromosomes of medaka as Sex-Linked 2 (SL2). Southern blot analyses suggested that the pHO5.110-related sequence was tandemly repetitive in the medaka genome. Using the clone as a probe for FISH analysis, strong hybridization signals were obtained in a couple of chromosomes that formed one of two large submetacentric chromosome pairs. The pHO5.110-related sequences were repetitive in the genomes of other species of Oryzias (O. curvinotus, O. luzonensis and O. mekongensis) that are karyologically related to O. latipes (all are members of the so-called biarmed group). By contrast, the sequences were not detected as repetitive in other Oryzias species. Hence, it is thought that pHO5.110-related sequences were amplified in the genome of a common ancestor of the biarmed group.

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Section: Chromosome Preparation and Fishmentioning

confidence: 99%

Identification of the sex chromosomes of the medaka, Oryzias latipes, by fluorescence in situ hybridization

Matsuda

Matsuda²,

Hamaguchi³

et al. 1998

Cytogenet Genome Res

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“…The Thai medaka (Oryzias minutillus) is widely distributed in Thailand (Magtoon and Uwa, 1985). This species inhabits shallow ponds, ditches, and paddy fields (Magtoon et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Expression Levels of Hormone Receptors and Bone Morphogenic Protein in Fins of Medaka

et al. 2009

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In the genus Oryzias, the morphologies of the dorsal and anal fins are typical secondary sex characters. In the Japanese medaka (Oryzias latipes) and Thai medaka (Oryzias minutillus), androgen receptor (AR) expression levels in the dorsal, anal, and pectoral fins were higher in males than in females. Conversely, in both species estrogen receptor (ER) β expression levels in the dorsal and anal fins were higher in females than in males. AR and ERβ expression levels in the dorsal and anal fins of sex-undeterminable individuals of Thai medaka were intermediate between those in normal male and female Thai medaka. There was no difference in the bone morphogenic protein (Bmp) 2b expression level between male and female Japanese medaka. In contrast, the Bmp2b expression level in the dorsal fin of sex-undeterminable individuals was lower than in normal male and female Thai medaka. It is thus clear that androgen and estrogen regulate the sexdependent characters of fin morphology in both Oryzias species. In sex-undeterminable individuals of Thai medaka, the low levels of Bmp2b expression in the dorsal fin are evidence that androgen and estrogen are necessary for adequate expression of Bmp2b in the normal development of at least the dorsal fin.

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“…Since previous cytogenetic studies did not report heteromorphic sex chromosomes in this species (Magtoon and Uwa, 1985;Magtoon et al, 1992), we first searched for sex-linked DNA markers using expressed sequence tag (EST) markers established in O. latipes. Linkage analysis of isolated sex-linked markers showed that O. minutillus has an XX/XY sex determination system, and that its sex linkage map is homologous to an autosome of O. latipes.…”

Section: Identification Of the Sex-determining Locus In The Thai Medamentioning

confidence: 99%

Identification of the sex-determining locus in the Thai medaka, Oryzias minutillus

Nagai

Takehana

Hamaguchi

et al. 2008

Cytogenet Genome Res

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A sex-determining gene, DMY, which is comparable to the SRY gene in mammals, has been identified in the medaka, Oryzias latipes. Although Oryzias curvinotus, a closely related species to O. latipes also has DMY, this gene has not been found in other Oryzias fishes. It has recently been demonstrated that the sex chromosomes of Oryzias dancena and Oryzias hubbsi differ from those of O. latipes and these species have XX/XY and ZZ/ZW systems, respectively. This may suggest that Oryzias species have evolved different sex-determining genes on different sex chromosomes. In the present study, we investigated the sex determination mechanism in Oryzias minutillus, which is closely related to O. dancena and O. hubbsi. Linkage analysis using 14 isolated sex-linked DNA markers showed that this species has an XX/XY sex determination system. These sex-linked markers were located on linkage group 8 of O. latipes, suggesting that the sex chromosomes of O. minutillus are homologous to the autosomes of other Oryzias species. Furthermore, fluorescence in situ hybridization using a tightly sex-linked marker demonstrated that the XY sex chromosomes of O. minutillus and O. dancena were not homologous. These findings provide additional evidence for independent origins of sex chromosomes and sex-determining genes in these closely related species.

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Karyotype evolution and relationship of a small ricefish, Oryzias minutillus, from Thailand.

Cited by 15 publications

References 1 publication

Identification of the sex chromosomes of the medaka, <i>Oryzias latipes</i>, by fluorescence in situ hybridization

Identification of the sex chromosomes of the medaka, <i>Oryzias latipes</i>, by fluorescence in situ hybridization

Expression Levels of Hormone Receptors and Bone Morphogenic Protein in Fins of Medaka

Identification of the sex-determining locus in the Thai medaka, <i>Oryzias minutillus</i>

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