Md. Ahmad Ali

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In this study, we used a sensitive and specific radioimmunoassay to detect a substance which appears to be melatonin, an acetylation and methylation product of serotonin, in the eyes and central nervous system of the opisthobranch mollusc Aplysia californica. This identification was confirmed in the eyes by HPLC with fluorimetric detection. Melatonin(More)
Serotonin is believed to play an important role in the neuronal development of various invertebrates and mammals, but only one study has yet investigated the development of serotoninergic neurons in the brain of a teleost. In the present study, we investigate the development of serotoninergic neurons in the brain of the brook trout, Salvelinus fontinalis,(More)
The fish pineal organ contains typical and, in some species, modified photoreceptor cells involved in the photoperiodic control of melatonin production. In the majority of species studied, the rhythm in melatonin production is driven by an intra-pineal circadian oscillator synchronized by the light:dark cycle. In the present study, it is shown that the(More)
In the pineal organ of the pike (Esox lucius, teleost), the rhythmic production of melatonin by the photoreceptor cells is governed by a population of endogenous circadian oscillators, synchronized and entrained by the light/dark (L/D) cycle. Production of melatonin is inhibited by light and highly increased in the dark. In the present study, isolated and(More)
Melatonin secretion from cultured pineal complexes of the lamprey, Petromyzon marinus, was measured by radioimmunoassay (RIA) for 6 days under either a 12:12 light:dark cycle (L:D) or continuous darkness (D:D) at either 10 degrees or 20 degrees. Under the L:D cycle, melatonin release was completely suppressed during daytime and high during night-time, with(More)
The retina of a South American swamp eel, Synbranchus marmoratus (Synbranchidae), was studied by Golgi impregnation, light and electron microscopy. Its principal features include (1) the presence of a dense matrix, possibly a new type of tapetum lucidum, in the pigment epithelium, (2) a well developed photoreceptor layer containing large rods, single,(More)
Based on findings in various mammalian species, where exposure to electromagnetic fields decreased the nocturnal synthesis of the pineal secretory product melatonin, we investigated the effects of magnetic field (MF) exposure in a teleost fish, the brook trout (Salvelinus fontinalis). Fields were generated by Helmholtz coils (maximum flux density 40 microT,(More)
This paper presents the results of a comparative investigation of the retinas of two Hiodontids, the goldeye (Hiodon alosoides) and the Mooneye (H. tergisus) employing light and electron microscopy, cell isolation techniques as well as microspectrophotometry. Contrary to the observations of previous workers these species possess a duplex retina. The(More)
The pineal organ and retina were compared in developing charr and cisco, further in adult cisco, eel, creek chub, dace, zebrafish and black moli by opsin immunocytochemistry. In prehatching charr embryos, retinal rods and cones and pinealocytes displayed well-developed outer segments and formed synapses. Differentiation of the retina started centrally but(More)