• Development and Reproduction
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• v.17 no.1
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• pp.45-53
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• 2013

The action of melatonin within the body of animals is known to be mediated by melatonin receptors. Three different types of melatonin receptors have been identified so far in fish. However, which of these are specifically involved in puberty onset is not known in fish. We cloned and analyzed the sequence of melatonin receptor 1a (mel 1a) gene in Nile tilapia Oreochromis niloticus. In addition, we examined the tissue distribution of gene expressions for three types of receptors, mel 1a, 1b and lc and investigated which of them is involved in the onset of puberty by comparing their expression with that of gonadotropin-releasing hormone receptor I (GnRHr I) gene using quantitative real-time PCR from 1 week post hatch (wph) to 24 wph. The mel 1a gene of Nile tilapia consisted of two exons and one bulky intron between them. Mel 1a gene was found to be highly conserved gene showing high homology with the corresponding genes from different teleost. All three types of melatonin receptor genes were expressed in the brain, eyes and ovary in common. Expression of mel 1a gene was the most abundant and ubiquitous among 3 receptors in the brain, liver, gill, ovary, muscle, eye, heart, intestine, spleen and kidney. Mel 1b and mel 1c genes were, however, expressed in fewer tissues at low level. During the development post hatch, expressions of both mel 1a and GnRHr I genes significantly increased at 13 wph which was close to the putative timing of puberty onset in this species. These results suggest that among three types of receptors mel 1a is most likely associated with the action of melatonin in the onset of puberty in Nile tilapia.

• Development and Reproduction
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• v.6 no.1
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• pp.45-54
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• 2002

Reproductive activity of golden hamsters(Mesocricetus auratus) is regulated by the photoperiod. They are sexually active in summer and inactive in winter. Melatonin, a pineal hormone, has been known to mediate sexual activities in seasonal breeding animals. Melatonin receptor was recently identified in several animal species including hmm. But little has been known about it in relation to the reproductive activities of golden hamsters. By using reverse transcription polymerase chain reaction(RT-PCR) methods, a portion of the melatonin receptor gene(309 nucleotides) was identified in golden hamsters. The nucleotide sequence of the melatonin receptor and the amino acid sequence deduced were compared to those reported in other animals. Melatonin receptors were obviously detected in hypothalamus, pituitary containing pars tuberalis, blood, and spleen. Although the testicular weights and the levels of reproductive hormones were dramatically affected by photoperiods, the expression of melatonin receptor was not markedly changed by them. These results suggest that the action of melatonin in regulating reproduction might be mainly due to the affinity of melatonin receptor rather than the density fi melatonin receptor.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.12
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• pp.1701-1704
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• 2003

Melatonin regulates circadian rhythms and reproduction changes in seasonally reproductive mammals through binding to high-affinity, G-protein-coupled receptors. Small Tail Han sheep that has significant characteristics of high prolificacy and nonseasonal ovulatory activity is an excellent local sheep breed in P. R. China. The exon 2 of the ovine melatonin receptor 1a (MTNR1A) gene was amplified and a uniform fragment of 824 bp was obtained in 150 ewes of Small Tail Han sheep. The 824 bp PCR product was digested with restriction endonucleases Mnl I and Rsa I, and genetic polymorphism was detected by PCR-RFLP. Polymorphic Mnl I site was detected at base position 605 of the exon 2 of the MTNR1A gene. There were two kinds of genotypes in Small Tail Han sheep, AB (303 bp, 236 bp/67 bp) and BB (236 bp/67 bp, 236 bp/67 bp). The results indicated that genotype AA (303 bp, 303 bp) at Mnl I-RFLP site did not exist in non-seasonal estrous Small Tail Han sheep, which suggested that there was an association between genotype AA (303 bp, 303 bp) and reproductive seasonality in sheep. Polymorphic Rsa I site was detected at base position 604 of the exon 2 of the MTNR1A gene. Three kinds of genotypes were found in Small Tail Han sheep, AA (290 bp, 290 bp), AB (290 bp, 267 bp/23 bp) and BB (267 bp/23 bp, 267 bp/23 bp). Least squares means of litter size in the first parity and the second parity for genotype AA (290 bp, 290 bp) at Rsa I-RFLP site were 0.43 and 1.06 more than those for genotype AB (290 bp, 267 bp/23 bp) in Small Tail Han sheep.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.8
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• pp.1079-1084
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• 2006

To determine whether a link exists between reproductive seasonality and the structure of the melatonin receptor 1A (MTNR1A) gene, the latter was studied in nonseasonal estrous breeds (Small Tail Han and Hu ewes) and seasonal estrous breeds (Dorset, Suffolk and German Mutton Merino ewes). A large fragment of the exon 2 of the MTNR1A gene was amplified and a uniform fragment of 824 bp was obtained in 239 ewes of five breeds. The 824 bp PCR product was digested with restriction endonucleases Mnl I and Rsa I, and checked for the presence of restriction sites. The presence (allele M) or absence (allele m) of an Mnl I site at base position 605 led to three genotypes MM (236 bp/236 bp), Mm (236 bp/303 bp) and mm (303 bp/303 bp) in five sheep breeds. The presence (allele R) or absence (allele r) of a Rsa I site at base position 604 led to three genotypes RR (267 bp/267 bp), Rr (267 bp/290 bp) and rr (290 bp/290 bp) in five sheep breeds. Frequencies of MM and RR genotypes were obviously higher, and frequencies of mm and rr genotypes were obviously lower in nonseasonal estrous sheep breeds than in seasonal estrous sheep breeds. Sequencing revealed four mutations (G453T, G612A, G706A, C891T) in mm genotype compared to MM genotype and one mutation (C606T) in rr genotype compared to RR genotype. For polymorphic Mnl I and Rsa I cleavage sites, the differences of genotype distributions were very highly significant (p<0.01) between Small Tail Han ewes and seasonal estrous sheep breeds. In each group, no significant difference (p>0.05) was detected. These results preliminarily showed an association between MM, RR genotypes and nonseasonal estrus in ewes and an association between mm, rr genotypes and seasonal estrus in ewes.

• Korean Journal of Environmental Biology
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• v.20 no.3
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• pp.224-231
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• 2002

Photoperiod (length of light per day) is a major factor in regulating reproductive function in golden hamsters. The information of photoperiod is transmitted to the reproductive endocrine system by melatonin. Thus the effects of melatonin aye investigated in male golden hamsters exposed to photoperiods. Paired testicular weights were markedly reduced in the animals housed in short photoperiod $(SP,\le{12\;hours\;day^{-1})$ and injected with melatonin in the evening, but not in long photoperiod $(LP,\le{12.5}\;hours\;day^{-1})$ and injected with melatonin in the morning. The histological examination of regressed testes showed reduction of tubular lumen diameter including the numbers of cells and Leydig cell number. The mean values of both follicle stimulating hormone (FSH) and luteinizing hormone (LH) were also lowered in the sexually inactive animals than in the sexually active animals. Melatonin receptor was identified by reverse-transcription polymerase chain reaction (RT-PCR) and its expression was examined in various tissues to scrutinize the action site of melatonin. It turned out 309 nucleotides and was definitely expressed in hypothalamus and pituitary including spleen, retina, and epididymis. And gonadotropin releasing hormone (GnRH) gene, which is a key element in regulating reproduction, was identified by RT-PCR but the expression of GnRH was not modified by the treatment of melatonin. Taken together, photoperiod via melatonin indirectly affects reproductive endocrine system, possibly through the release of GnRH, not the synthesis of GnRH.

• Ocean and Polar Research
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• v.46 no.1
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• pp.55-64
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• 2024

Light is an external environmental factor that affects the biorhythms of aquatic organisms and is involved in their behavior, reproduction, and various biological responses. The biorhythm (24-h cycle) of organisms is controlled internally by clock genes, such as period (Per), cryptochrome (Cry), and melatonin receptor (MT-R), and is externally controlled by light, food, and temperature. In this study, the experimental organisms were divided into photoperiod and LED groups. The photoperiod group was exposed to two photoperiods (LD, 12 h light: 12 h darkness; DD, constant darkness), and the LED group was exposed to a red LED light (wavelength, 630 nm; 12 h LED light: 12 h darkness). Per and Cry mRNA expression levels increased during the bright phase and decreased during the dark phase. MT-R mRNA expression decreased during the bright period and increased during the dark period. The trend in clock gene expression in the RD group was similar to that in the DD group but not in the LD group. Red LED irradiation induced gene expression similar to the 24 h memorization condition, suggesting that long-wavelength light conditions can change the biorhythm of abalones. This study provides academic information on the biorhythm cycle of abalone (a marine gastropod), which is less well known than that of fish and can aid in predicting the physiological response of abalones to changes in light wavelength.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.1
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• pp.29-40
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• 2010

This study was aimed at investigating the gene expression profile in basal ganglia of cadmium exposed rat based on cDNA array analysis. For cDNA array analysis, adult Sprague-Dawley male rats (350 ${\pm}$ 25 g) were intraperitoneally injected with 2.0 mg/kg body weight/day of CdCl2 (0.3 ml) for 5 days. For doserelated gene expression analysis rats were intraperitoneally injected with 0.0, 0.1, 0.3, 1.0 mg/kg body weight/day of CdCl$_2$ for 5 days. Control rats were injected with equal volume of saline. Cadmium concentration of brain was analyzed by atomic absorption spectrophotometer. For cDNA array, RNA samples were extracted from basal ganglia and reverse-transcribed in the presence of [${\alpha}$32P]-dATP. Membrane sets of the Atlas Rat 1.2 array II and Toxicology array 1.2 (Clontech, Palo Alto, CA) were hybridized with cDNA probe sets. RT-PCR was employed to validate the relative gene expression patterns obtained from the cDNA array. Northern blot hybridization methods were employed to assess the dose-related gene expression. Among the 2352 cDNAs, 671 genes were detected in both array sets and 63 genes of 38 classes showed significant (more than two fold) changes in expression. Thirty five of these genes were up-regulated and twenty eight were down-regulated in the cadmium exposed group. According to the dose-related gene expression analysis, heat shock 27 kDa protein (HSP27), neurodegeneration-associated protein 1 (Neurodap 1) genes were significantly up-regulated and melatonin receptor 1a (Mel1a), Kinesin family member 3C (KIF3C), novel kinesinrelated protein (KIF1D) genes were significantly downregulated even in the low-dose of cadmium exposed group (0.1 mg/kg body weight/day). Conclusions Sixty three genes detected in this study can give some more useful informations about the cadmium-induced neurotoxicity in the basal ganglia. As well as, HSP27, Neurodap1, Mel1a, KIF3C and KIF1D genes may be useful for the study of the cadmium-induced neurotoxicity because these genes showed dramatic changes of mRNA levels in response to the low dose of cadmium exposure.

• Animal Bioscience
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• v.34 no.9
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• pp.1569-1578
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• 2021

Objective: This study was conducted to investigate the potential effects of prolonged photoperiod on the serum lipids, carcass traits, and meat quality of Jinjiang cattle during winter. Methods: Thirty-four Jinjiang bulls aged between 14 and 16 months were randomly assigned to two groups that were alternatively subjected to either natural daylight +4 h supplemental light (long photoperiod, LP) or natural daylight (natural photoperiod, NP) for 96 days. The potential effects on the levels of serum lipids, carcass traits, meat quality, and genes regulating lipid metabolism in the intramuscular fat (IMF) of the cattle were evaluated. Results: Jinjiang cattle kept under LP showed significant increase in both dry matter intake and backfat thickness. the serum glucose and the plasma leptin levels were significantly reduced, while that of melatonin and insulin were observed to be increased. The crude fat contents of biceps femoris muscle and longissimus dorsi muscle were higher in LP than in NP group. In longissimus dorsi muscle, the proportions of C17:0 and C18:0 were significantly higher but that of the C16:1 was found to be significantly lower in LP group. The relative mRNA expressions in IMF of longissimus dorsi muscle, the lipid synthesis genes (proliferator-activated receptor gamma, fatty acid-binding protein) and the fatty acid synthesis genes (acetyl-coa carboxylase, fatty acid synthetase, 1-acylglycerol-3-phosphate acyltransferase) were significantly up-regulated in LP group (p<0.05); whereas the hormone-sensitive lipase and stearoyl-CoA desaturase 1 were significantly down-regulated in LP than in NP group. Conclusion: Prolonged photoperiod significantly altered the growth performance, hormonal levels, gene expression and fat deposition in Jinjiang cattle. It suggested that the LP improved the fat deposition by regulating the levels of different hormones and genes related to lipid metabolism, thereby improving the fattening of Jinjiang cattle during winter.

• 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.