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1

Effects of the herbicide pendimethalin on hormone receptor expressions and dorsal fin biometrics in Thai medaka, Oryzias minutillus (Actinopterygii: Beloniformes: Adrianichthyidae)

100%
Ngamniyom A., Panyarachun B.
Acta Ichthyologica et Piscatoria
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2012
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tom 42
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nr 3
Background. Xeno-oestrogens have negative effects on the endocrine systems of wildlife including freshwater fish. Pendimethalin is a herbicide found in the environment which exerts some oestrogenic action in vivo. Dwarf medaka (known also as Thai medaka), Oryzias minutillus Smith, 1945, inhabit the natural aquatic environments. Dorsal fin of this species is a secondary sex character controlled by sex hormones and assumes as a sensitive bioindicator for testing of oestrogenic chemicals. In this study, we aimed to examine the pendimethalin effects on hormone receptor expressions and dorsal fin biometrics in adult Thai medaka. Materials and Methods. Pendimethalin effects on the androgen receptor (AR) and estrogen receptor (ER) β expressions in dorsal fins were determined by semi-quantitative RT-PCR. The fin biometry was presented as the values (%) of the dorsal fin length (DFL) divided by the standard length (SL). Results. In males, AR levels decreased when the fish were exposed to 0.1 µg · mL–1 pendimethalin for 60 days and were exposed to 1 µg · mL–1 for 30 and 60 days. In females, a 60-day treatment with 1 µg · mL–1 caused AR levels to decrease. Conversely, in males, ERβ levels increased after 30 and 60 days of treatment with 1 µg · mL–1. In females, ERβ levels increased after 30 days of treatment with 1 µg · mL–1 and 60 days of treatment with 0.1 µg · mL–1. In males, values of DFL/SL% decreased after exposure to 1 µg · mL–1 for 60 days. Additionally, we observed 4 testis-ova among 30 gonads from males treated with 1 µg · mL–1 for 60 days. Conclusion. Our results suggest that pendimethalin may interfere with endocrine processes via hormone receptors, leading to the feminisation of dorsal fins and gonads in Thai medaka
2

Expression levels of sex hormone receptors in brains ofJapanese medaka, Oryzias latipes (Actinopterygii: Beloniformes: Adrianichthyidae)

100%
Ngamniyom A., Sasayama Y.
Acta Ichthyologica et Piscatoria
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2011
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tom 41
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nr 1
Background. In teleost fishes, the brain is the target organ for sex steroid hormones. The actions of sex steroid hormones are mediated by their receptors and play an important role in the regulation of endocrine function in the brain. Japanese medaka, Oryzias latipes, is a species widely used in many fields of experimental biology, including neurobiology. In this study, we examined the mRNA expression levels of androgen and estrogen receptors in medaka brains. Materials and Methods. The brains of adult fish were separated into three parts (forebrain, midbrain and hindbrain). The expression levels of androgen receptor (AR) and estrogen receptor (ER) β from each part of the brain were determined using a semi-quantitative RT-PCR analysis. Results. AR and ERβ levels in males were higher in the forebrain and midbrain than in the hindbrain. In females, AR and ERβ levels were higher in the forebrain than in the midbrain and hindbrain. AR levels in the forebrain and midbrain of males were higher than those of females. Conversely, there was no difference in ERβ level between males and females. Conclusion. These data on hormone receptors provide the foundation for understanding the molecular basis of AR and ERβ mRNA expression levels in medaka brains. In addition, our results suggest that, in Japanese medaka, AR, but not ERβ, expression may exhibit sexual dimorphisms between males and females in the forebrains and midbrains.
3

Investigation of hormone receptor expressions in the fins of Oryzias woworae (Actinopterygii: Beloniformes: Adrianichthyidae)

81%
Ngamniyom A., Sriyapai T., Somyoonsap P.
Acta Ichthyologica et Piscatoria
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2014
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tom 44
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nr 3
Background. In the genus Oryzias, the morphology of the dorsal and anal fin constitute typical secondary sex characteristics that are controlled by sex steroid hormones through hormone receptors. However, the level expressions of hormone receptors in fish fins of this genus have remained to be clarified. To achieve the aims of this study, we completely examined the patterns of hormone receptor expression in all fin types of adult Oryzias woworae Parenti et Hadiaty, 2010. Materials and Methods. The androgen receptor (AR) α, ARβ, oestrogen receptor (ER) α, and ERβ expression in the dorsal-, anal-, pectoral-, pelvic-, and caudal fins, including the dorsal and ventral edges of the caudal fins, were determined using semi-quantitative RT-PCR. Results. Hormone receptor expression levels were significantly different in the dorsal-, anal-, and caudal fins of males, including the dorsal and ventral edges of their caudal fins, and in the pectoral and pelvic fins, and the dorsal and ventral edges of the caudal fins of females. ARα and ARβ levels in dorsal fins and ARβ levels in anal and caudal fins were higher in males than in females. ERα levels in pectoral fins were higher in males than in females. Conversely, ERβ levels in the pectoral and pelvic fins and in the dorsal and ventral edges of caudal fins were higher in females than in males. Conclusion. These results suggest that AR- and ER-mediated functions may regulate sexual dimorphism, and that characteristics of fin morphology are dependent on androgen and oestrogen regulation in adult Oryzias woworae.
4

The anthelmintic effects of medicinal plant extracts against paramphistome parasites, Carmyerius spatiosus

51%
Minsakorn S., Nuplod K., Puttarak P., Chawengkirttikul R., Panyarachun B., Ngamniyom A., Charoenkul T., Jaisa-aad M., Panyarachun P., Anuracpreeda P.
Acta Parasitologica
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2019
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tom 64
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nr 3
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