Migratory culture, population structure and stock identity in North Pacific beluga whales (Delphinapterus leucas).

The annual return of beluga whales, Delphinapterus leucas, to traditional seasonal locations across the Arctic may involve migratory culture, while the convergence of discrete summering aggregations on common wintering grounds may facilitate outbreeding. Natal philopatry and cultural inheritance, however, has been difficult to assess as earlier studies were of too short a duration, while genetic analyses of breeding patterns, especially across the beluga's Pacific range, have been hampered by inadequate sampling and sparse information on wintering areas. Using a much expanded sample and genetic marker set comprising 1,647 whales, spanning more than two decades and encompassing all major coastal summering aggregations in the Pacific Ocean, we found evolutionary-level divergence among three geographic regions: the Gulf of Alaska, the Bering-Chukchi-Beaufort Seas, and the Sea of Okhotsk (Φst = 0.

Melatonin plays a protective role in quinolinic acid-induced neurotoxicity in the rat hippocampus.

The neuroprotective effect of melatonin against the quinolinic acid-induced degeneration of rat hippocampal neurons was investigated. Three groups of rats were given intrahippocampal injections of either; saline, quinolinic acid or i.p.

Evidence for a modulation of the stress response by the pineal gland.

Wistar rats show a circadian variation in their response to stress. Pinealectomy exacerbates stress-induced gastric ulceration in rats. This effect is counteracted by melatonin administration.

The effect of melatonin on the formation of gastric stress lesions in rats.

Prior melatonin administration (1,5 and 10 mg/kg b. wt) causes a significant reduction in gastric ulceration induced in male rats by restraint immobilization in the presence of low temperatures.