Effects of retinal light input on circadian rhythm genes in the yellowtail clownfish (Amphiprion clarkii) as determined using LED light spectra

Abstract

The objective of this study was to test the effects of ophthalmectomy on the circadian rhythms in response to various wavelengths in yellowtail clownfish. The responses were evaluated by measuring rhodopsin (RH) and melatonin receptor 1 (MT1) mRNA and protein expression, and plasma melatonin levels. The RH, MT1 mRNA, and protein expression in ophthalmectomized fish were significantly lower than in intact fish. However, RH and MT1 mRNA and protein expression levels in green and blue light-emitting diode groups were similar between intact and ophthalmectomized fish. Furthermore, we found that the number of the RH-immunoreactive cells observed in the retina was almost in agreement with mRNA and protein expression patterns. These findings suggest that circadian rhythm involves the perception of light by the eye and the transduction of this signal through the circadian rhythm axis. Furthermore, short wavelengths lights may be most suitable for control of the circadian rhythm in fish.

Feeding regimes affected the circadian rhythms of pancreatic digestive enzymes and somatic growth in flathead grey mullet (Mugil cephalus) fry

“…in both marine and freshwater fish species (Delahunty et al, 1978;Aranda et al, 1999;Nordgarden et al, 2003;Kousoulaki et al, 2015;Navarro-Guillén et al, 2018). The rhythmicity of the above-mentioned patterns under natural conditions is dependent on a broad range of different biotic and abiotic factors that may be listed as water temperature (Fraser et al, 1993), the light/dark ratio (Cuenca and de la Higuera, 1993;Aranda et al, 1999), light intensity (Fraser and Metcalfe, 1997) and spectrum (Choi et al, 2014), feeding regime (Yúfera et al, 2014), concentration of dissolved gases in water, food density and availability (Modica et al, 2014), competition with other fish species and among different individuals of the same species, among others. Under aquaculture conditions, the number of these factors tends to be lower because many of the abovementioned factors could be easily controlled and/or their range of variability substantially reduced.…”