Seasonal variation in fish school spatial distribution and abundance under the Kuroshio regular pattern and the large meander in Suzu coastal waters.

The Kuroshio Current can take two paths; usually it follows the regular pattern but occasionally it follows a pattern known as the large meander. In this study, we investigated the abundance of fish that migrate to coastal waters and the spatial distribution of fish schools under both Kuroshio patterns in Suzu district, Kochi prefecture, where the set net is the main fishery industry. We clarified the seasonal variation in the density and distribution of fish schools using a quantitative echo sounder. The effects of the Kuroshio large meander (LM) depended on the season. There was no effect of current pattern in summer or autumn, but in winter and spring the LM altered the marine environment and fish distributions. Cold water masses were formed in the survey area during winter and spring during the LM, and the water temperature dropped significantly compared with during the Kuroshio non-large meander (NLM). This altered the fish species and the distribution of fish schools in the survey area. The catches of Japanese horse mackerels (Trachurus japonicus) and Yellowtails (Seriola quinqueradiata) were much higher during the LM compared with those during the NLM. Unlike these two species, the small-sized pelagic fishes in spring has decreased significantly during the LM.

Non-genomic action of 17beta-estradiol on opening of Ca(2+)- and voltage-activated K+ channel in lacrimal acinar cells.

The effect of the sex hormone 17 beta-estradiol on the opening of Ca(2+)- and voltage-activated K+ channels (BK channels) in the basolateral plasma membrane of mouse lacrimal acinar cells was studied by patch-clamp single-channel recording and Ca(2+)-measurement using fura-2 AM. In intact cells (the cell-attached configuration) using a pipette containing a Na+ -rich solution, estradiol was added to the bath solution, which does not have direct contact with the electrically isolated areas of membrane patch from which the single-channel currents were recorded. Estradiol increased the frequency of opening of the BK channels within a few minutes after its application. The effect of estradiol on the opening of the BK channels in acinar cells in male mice was greater than that in females. In Ca(2+)-measurement using fura-2 AM, estradiol did not increase the level of intracellular Ca2+ during a 5-minute observation period. The application of estradiol with propranolol, a beta-adrenergic receptor blocker, did not increase BK channel opening. The application of estradiol with Rp-cAMPS, an inhibitor of cyclic AMP-dependent protein kinase (protein kinase A), also inhibited the increase in channel opening. The addition of a catalytic unit of protein kinase A to the inside of the excised membrane patch increased the frequency of opening of the BK channels. These results suggest that estradiol interacts with beta-adrenergic receptor on the basolateral membrane and regulates the opening of BK channels by protein phosphorylation via a cyclic AMP pathway, without a change in the Ca2+ level.