CasEcR and CasMIH Genes in the Blue Crab, Callinectes sapidus: A Temporal Evaluation and Melatonin Effects

Abstract

Environmental cues synchronize endogenous rhythms of many physiological processes such as hormone synthesis and secretion. Little is known about the diurnal pattern of hormones and gene expression of the Callinectes sapidus molt cycle. We aimed to investigate in the eyestalk and hepatopancreas of premolt and intermolt C. sapidus the following parameters: 1) the diurnal expression of the ecdysteroid receptor CasEcR isoforms, and the molt inhibiting hormone CasMIH; 2) the diurnal hemolymph ecdysteroid and melatonin levels; and 3) melatonin effects on the transcripts of the above-mentioned genes in intermolt C. sapidus. Ecdysteroid levels were higher in the premolt than the intermolt animals at all time points evaluated (ZTs). Premolt crabs displayed a variation of ecdysteroid concentration between time points, with a reduction at ZT17. No difference in the melatonin level was seen in either molt stage or between stages. In the eyestalk of intermolt animals, CasEcR expression oscillated, with a peak at ZT9, and premolt crabs have a reduction at ZT9; CasMIH transcripts did not vary along 24 h in either molt stage. Moreover, the evaluated eyestalk genes were more expressed at ZT9 in the intermolt than the premolt crabs. In the hepatopancreas, CasEcR expression showed a peak at ZT9 in premolt crabs. Exogenous melatonin (10−7 mol/animal) reduced the expression of both genes in the eyestalk at ZT17. In the hepatopancreas, melatonin markedly increased the expression of the CasEcR gene at ZT9. Taken altogether, our results are pioneer in demonstrating the daily oscillation of gene expression associated to molt cycle stages, as well as the daily ecdysteroid and melatonin levels and the remarkable influence of melatonin on the molt cycle of C. sapidus.

Melatonin injection and red light irradiation affect the antioxidant response and cell damage in disk abalone (Haliotis discus hannai) exposed to high water temperatures

“…as a control (Figure 1). The melatonin injection concentrations of 10 −7 M (Mel −7 ) and 10 −8 M (Mel −8 ) were selected following prior experiments (David et al, 2022; Gao et al, 2023), and 100 μL per individual was injected into the pedal sinus using a syringe. The control and melatonin injection groups were exposed to light produced by a white fluorescent bulb, while the red LED light‐irradiated group was exposed to light produced by a red (630‐nm wavelength) LED (Total LED Co.).…”

Efeito da temperatura no siri-azul Callinectes sapidus (BRACHYURA:PORTUNIDAE): aspectos fisiológicos, moleculares e proteômicos

“…Este aumento da secreção de MIH no fim da pré-muda observado em algumas espécies (Nakatsuji e Sonobe, 2004) vem sendo estudado como um feedback positivo dos ecdisteroides sobre a expressão de MIH e negativo sobre sua própria síntese e o ciclo de muda (Techa e Chung 2015;David et al, 2022). O receptor de ecdisteroides (EcR) é um heterodímeiro de EcR e RXR (receptor do ácido retinóico em crustáceos), sendo 4 isoformas (CasEcR1, CasEcR1a, CasEcR2 e CasEcR2a) descritas para C. sapidus (Techa e Chung, 2013).…”

“…Esta espécie é também modelo para diversos estudos como ciclo de vida, regulação neuroendócrina do ciclo de muda e papel do cálcio no ciclo de muda (Freeman et al, 1987;Hines et al, 1987;Havens e McConaugha, 1990;Chung, 2010;Chen e Watson, 2011;Chen et al, 2012;Techa e Chung, 2013;Techa e Chung, 2015;David et al, 2022), entre outros.…”

“…A expressão de EcR no complexo neuroendócrino do pedúnculo óptico também já foi estabelecida. Este receptor está presente na região promotora do gene codificador do MIH e, quando os ecdisteroides atingem certos níveis circulantes, estes regulam positivamente a síntese de MIH via ligação a seus receptores (Techa e Chung, 2015;David et al, 2022). A expressão dos receptores no pedúnculo óptico de espécimes de C.…”