Role of Aralkylamine N-Acetyltransferase in the Response to Antioxidative Stress in the Fruit Fly Drosophila Melanogaster Adults.

In multicellular organisms, the indole melatonin synthesized by aralkylamine N-acetyltransferase (AANATI) serves as an antioxidant. To test this, sex-mixed 3-day-old mated fly adults bw and AANAT1 homozygous recessive loss-of-function mutant (bw AANAT1) of Drosophila melanogaster were fed by a standard diet or by one containing paraquat (PQ, 1,1'-dimethyl-4,4'-bipyridilium dichloride hydrate) at a final concentration of 15.5 mM.

Daily rhythmic expression patterns of clock1a, bmal1, and per1 genes in retina and hypothalamus of the rainbow trout, Oncorhynchus mykiss.

Living organisms show daily rhythms in physiology, behavior, and gene expression, which are due to the presence of endogenous clocks that synchronize biological processes to the 24-h light/dark cycle. In metazoans, generation of circadian rhythmicity is a consequence of specialized tissues known as "master clocks," having different locations among species. A few studies have described clock-gene expression in fish neural tissues, but none of them assessed clock-gene expression in different discrete regions.

Changes in plasma melatonin levels and pineal organ melatonin synthesis following acclimation of rainbow trout (Oncorhynchus mykiss) to different water salinities.

Melatonin has been suggested to play a role in fish osmoregulation, and in salmonids has been related to the timing of adaptive mechanisms during smolting. It has been described that acclimation to different environmental salinities alters levels of circulating melatonin in a number of fish species, including rainbow trout. However, nothing is known regarding salinity effects on melatonin synthesis in the pineal organ, which is the main source of rhythmically produced and secreted melatonin in blood.

Diurnal rhythms in hypothalamic/pituitary AVT synthesis and secretion in rainbow trout: evidence for a circadian regulation.

Arginine vasotocin (AVT) and isotocin (IT) are two neurohypophysial peptide hormones for which a role in adaptation to environmental changes has been suggested in fish. In teleosts, there are only a few available studies about circadian changes of AVT and IT levels, and a role of those peptides in the circadian system has been mainly suggested on the basis of the role of the homologous hormone AVP in mammals. Herein, we evaluated the diurnal rhythms in plasma AVT, pituitary AVT and IT content and the hypothalamic pro-vasotocin (pro-VT) expression in rainbow trout kept under a natural photoperiod, as well as their persistence in constant darkness as a tool for defining circadian dependence.

Effects of naphthalene, beta-naphthoflavone and benzo(a)pyrene on the diurnal and nocturnal indoleamine metabolism and melatonin content in the pineal organ of rainbow trout, Oncorhynchus mykiss.

Polycyclic aromatic hydrocarbons (PAHs) have deleterious effects on neuroendocrine systems in teleost fish affecting, among other processes, reproductive function or stress responses. The hormone melatonin, mainly produced in the pineal organ of vertebrates, is involved in the regulation of biological rhythms as well as other important functions, and may also act as an antioxidant molecule. The effects of environmental pollutants on the endocrine and metabolic activity of the pineal organ have been studied only in mammals.

Food deprivation and refeeding effects on pineal indoles metabolism and melatonin synthesis in the rainbow trout Oncorhynchus mykiss.

The effects of food deprivation and refeeding on daily rhythms of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and melatonin contents, as well as on arylalkylamine N-acetyltransferase (AANAT) activity were evaluated in the pineal organ of rainbow trout. In addition, changes in circulating melatonin and cortisol levels were tested at one single point at day and night. Immature rainbow trout were distributed in 3 experimental groups: fish fed, fish fasted (7 days), and fish fasted for 7 days and refed for 5 days.