• Development and Reproduction
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• v.23 no.2
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• pp.149-160
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• 2019

This study examined the effects of different photoperiod conditions on olive flounder (Paralichthys olivaceus), a commercially important species in Korea. Daily variations in the expression of mRNA for the growth-related genes arylalkylamine N-acetyltransferase2 (AANAT2), preprosomatostatin1 (PSS1), and growth hormone (GH) were examined under a 12 h light:12 h dark photoperiod. All the genes were expressed at higher level during the dark period. Melatonin injections increased the expression of GH, but did not significantly affect the expression of PSS. Under short-day conditions (10 h:14 h), the fish gained more weight than under long-day conditions (14 h:10 h). A long nighttime induced melatonin secretion and increased the expression of GH mRNA, promoting weight gain in this species. Therefore, we thought that the long day condition in raising olive flounder may be effective in inducing body growth.

• Journal of Marine Life Science
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• v.9 no.1
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• pp.47-52
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• 2024

Light is a major external environmental factor that influences the circadian rhythm of photosynthetic organisms and various physiological phenomena, such as growth, maturation, and behavior. The number of light-reaching organisms changes depending on the season and atmospheric conditions, and the intensity and wavelength of light differ depending on the organisms inhabiting the environment. Altered light changes the circadian rhythm of fish, which is controlled by clock genes, such as period 2 (Per2), cryptochrome 1 (Cry1), and melatonin. In this study, we set the zeitgeber time (ZT; 14 light-10 dark, LD) based on the actual sunrise and sunset times and examined Per2 and Cry1 activities, levels of aralkylamine N-acetyltransferase (AANAT), and melatonin in Pholis nebulosa, a drifting seaweed species exposed to irregular light. Per2 and Cry1 levels increased during the daytime and decreased after sunset. The AANAT levels decreased during the daytime and increased during the night. Melatonin concentration was highest around midnight (ZT21, 23:30), but exhibited similar concentrations during the daytime. While the activity of Per2, Cry1, and AANAT levels exhibited a typical circadian rhythm observed in most vertebrates, melatonin concentrations did not show a significant difference between the daytime and nighttime. These findings provide insights into the circadian rhythm patterns of organisms exposed to irregular light environments, such as P. nebulosa, which differ from those of typical fish species.

• Journal of Animal Science and Technology
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• v.57 no.3
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• pp.8.1-8.8
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• 2015

Background: The demand for healthy, lean and consistent meat products containing low saturated fatty acid content and high quality polyunsaturated fatty acids (PUFA), especially long-chain (${\geq}C_{20}$) omega-3 PUFA, has increased in recent times. Fat deposition is altered by both the genetic background and dietary supplements, and this study aimed to assess the effect of dietary Spirulina supplementation levels on the mRNA expression patterns of genes controlling lipid metabolism in the subcutaneous adipose tissue (SAT) and Longissimus dorsi (ld) muscle of Australian crossbred sheep. Methods: Twenty-four weaned lambs belonging to four breeds under the same management conditions were maintained on ryegrass pasture and fed three levels of Spirulina supplement (control, low and high). In terms of nutrient composition, Spirulina is a nutrient-rich supplement that contains all essential amino acids, vitamins and minerals. It also is a rich source of carotenoids and fatty acids, especially gamma-linolenic acid (GLA) that infer health benefits. After slaughter, subcutaneous adipose tissue (SAT) and ld samples were subjected to mRNA extraction and reverse transcription using quantitative polymerase chain reaction (RT-qPCR) to assess the mRNA expression levels of the Aralkylamine N-acetyltransferase (AANAT), Adrenergic beta-3 receptor (ADRB3), B-cell translocation gene 2 (BTG2) and Fatty acid synthase (FASN) genes, which are associated with lipid metabolism. Results: Both low and high Spirulina supplementation levels strongly up-regulated the transcription of all the selected genes in both SAT and ld tissues (mostly in the subcutaneous adipose), but sheep breed and sex did not influence the gene expression patterns in these tissues. Conclusions: The evidence indicates that high Spirulina supplementation level resulted in a decrease in intramuscular fat content in Australian purebred and crossbred sheep due to the enhanced production of melatonin in sheep muscle tissues and strong up-regulation of mRNA expression of BTG2 in SAT which negatively affected fat deposition. In contrast, low Spirulina supplementation level strongly up-regulated the ADRB3 and FASN genes responsible for fat production. These findings are consistent with the observed phenotypic data suggesting that low Spirulina supplementation level can increase lamb production, with higher long-chain PUFA content.

• Animal cells and systems
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• v.16 no.1
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• pp.27-33
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• 2012

The suprachiasmatic nucleus (SCN) of the teleost hypothalamus contains a central circadian pacemaker, which adjusts circadian rhythms within the body to environmental light-dark cycles. It has been shown that exposure to darkness during the day causes phase shifts in circadian rhythms. In this study, we examined the effect of exposure to darkness on the mRNA expression levels of two circadian clock genes, namely, $Period2$ ($Per2$) and $Cryptochrome1$ ($Cry1$), and the rate-limiting enzyme in melatonin synthesis, arylalkylamine $N$-acetyltransferase-2 (Aanat2), in the pineal gland of olive flounder, $Paralichthys$ $olivaceus$. The expression of these genes showed circadian variations and was significantly higher during the dark phase. These changes may be involved in the mechanism of dark-induced phase shifts. Furthermore, this study suggests that olive flounder may be a teleost model to investigate the localization and function of circadian oscillators.