THE ORIGIN OF THE ACETYLCHOLINE RELEASED FROM THE SURFACE OF THE CORTEX

—The specific radioactivity of acetylcholine liberated from the surface of the rabbit occipital cortex has been compared with that of the underlying cortical synaptosomal and vesicular acetylcholine at varying times after the administration of [N-Me-³H]choline. Choline was administered by diffusion from solutions placed in cups formed by Perspex cylinders applied to the surface of the cortex. Acetylcholine was collected by diffusion into these cups. The specific radioactivity of the acetylcholine declined progressively. The effect of stimulation of afferent cholinergic pathways was to cause a fall in the specific radioactivity of the released acetylcholine. However this was always higher than that of the synaptosomal or vesicular acetylcholine as represented by fractions P₂ and D of the authors’fractionation scheme. It is concluded that acetylcholine released from the cortex must come from a store or stores more recently synthesized than the endogenous acetylcholine of these subcellular fractions.     

三峡库区甘井河水域牧场浮游植物群落结构及水质评价

为了解三峡库区的忠县甘井河段水域牧场生态渔业对水环境的影响, 于2013 年3、6、9 及12 月按季度对该河段4 个站点进行了浮游植物群落结构及水体理化因子的监测, 并采用生物多样性指数法和综合营养状态指数法对水体营养状况进行了评价。结果表明, 该河段浮游植物有7 门93 个属种, 其中绿藻门的物种数最多, 有37 种, 占浮游植物群落总数的39.79%, 其次为硅藻门和蓝藻门, 物种数分别为26 种和13 种,分别占浮游植物群落总数的27.96%和13.98%;浮游植物的年均丰度为757.67104 ind./L, 变化范围(3.065743.99)104 ind./L, 年均生物量为4.40 mg/L, 变化范围0.0317.67 mg/L;水体的年平均透明度为1.18 m, 叶绿素a、总磷、总氮含量分别为8.54 g/L、0.13 mg/L、1.95 mg/L;浮游植物香农多样性指数(H')、均匀度指数(J)年均值分别为2.90 和0.88, 全年综合营养状态指数值为37.5971.86, 由此推断, 甘井河水质属于中污染轻污染状态、中营养型富营养型。在鱼类生长旺季的6 月, 甘井河段养殖区内的水质优于非养殖区, 这可能与养殖区内放养滤食性鱼类有关, 证实了水域牧场没有带来水环境的污染, 反而能提高生物多样性, 在一定程度上改善了水体。