Introduction 318Cycles in relation to the moon 318Moon-related reproductive activity 319Reproductive season and lunar-related spawning rhythm of rabbitfishes 320Ovarian development and the lunar cycle 321Testicular development and lunar periodicity 323Environmental factors regulating lunar-related reproduction 324Closing remarks 325 Abstract Cues from the moon influence synchrony in growth, feeding, migration, behaviour and reproduction of many reef fishes. Compared with comprehensive studies on the annual and daily activities of fish, few physiological studies have paid attention to the importance of lunar cues in reproductive activities. We review mutual and interesting relationships between fish reproduction and environmental changes induced by the moon, with particular emphasis on the reproductive activity of the rabbitfishes (Siganidae). Rabbitfish species exhibit, in nature, a definitive reproductive season, which differs among the tropical areas. During the reproductive season, synchronous spawning of rabbitfish is associated with a particular lunar phase. The lunar phase used by the respective species is similar in different regions on the earth. Histological observations revealed that gonads develop synchronously towards a peak around the spawning lunar phase, after which the gonads return to spent condition. Concomitant with gonadal development, sex steroid hormones were produced under the influence of gonadotropin (GtH). Injections of human chronic gonadotropin (hCG) to the fish that are undergoing active spermatogenesis accelerated testicular maturation. These results suggest that hormonal response in maturing the gonads in rabbitfish is under the regulation of GtH, and that pituitary secretion of GtH according to the lunar cycle accounts for the lunar rhythm in gonadal development. We speculate that the cues from the moon can be recognized by the higher parts of the hypothalamus-pituitary-gonadal axis. Possible relationships between exogenous environmental factors and the lunar-reproductive rhythm are also discussed.

We cloned a cDNA for the rat Ic-opioid receptor from a rat thalamus cDNA library. The deduced amino actd sequence consists of 380 restdues with features shared by members of the G protein-coupled receptor family. The specific bmding of [3H]bremazocine to the membrane of COS-7 cells transfected with the cDNA was displaced by x-specific opioid ligands. but not by p-and S-specific Iigands. Xenopus oocytes injected with the m vitro transcribed mRNA responded to opioid hgands with the same subtype spectficity. Northern blot analysis demonstrated that Kc-optoid receptor mRNA is expressed in a regionally specific manner in rat brain.

This paper proposes natural drug candidate compounds for the treatment of coronavirus disease 2019 (COVID-19). We investigated the binding properties between the compounds in the Moringa oleifera plant and the main protease (Mpro) of severe acute respiratory syndrome coronavirus 2 using molecular docking and ab initio fragment molecular orbital calculations. Among the 12 compounds, niaziminin was found to bind the strongest to Mpro. We furthermore proposed novel compounds based on niaziminin and investigated their binding properties to Mpro. The results reveal that the introduction of a hydroxyl group into niaziminin enhances its binding affinity to Mpro. These niaziminin derivatives can be promising candidate drugs for the treatment of COVID-19.

Testosterone, 11‐ketotestosterone and 17α ,20β‐dihydroxy‐4‐pregnen‐3‐one in the forktail rabbitfish Siganus argenteus peaked around the full moon and the last quarter moon, respectively. Since changes in these hormones were correlated with histological change in the testis, the present study provided conclusive evidence for importance of the lunar periodicity in the reproductive activity of the forktail rabbitfish.