The opsins of the vertebrate retina: insights from structural,biochemical, and evolutionary studies

The vertebrate retina contains several classes of visual pigments responsible for such diverse functions as image- and nonimage-forming vision, the entrainment of circadian cycles, and the pupilary light response. With vision being vital to the survival of many species, the elucidation of the structural and biochemical properties of visual pigments has been the focus of a large body of research that has led to rapid advances in the field of photoreception. In this review, the current understanding of the structure, function, biochemistry, and evolution of the opsins that make up the photopigments in the vertebrate retina will be reviewed. These include the rod and cone opsins, melanopsin, RGR, peropsin, and VA-opsin. The goal is to highlight important questions that have been answered and to define some of the remaining questions in the field that will provide future directions for research.     

氮肥运筹对粮饲兼用型玉米生理特性的影响

以金山10为试验材料,采用不同氮肥用量及氮肥与有机肥配比试验,研究了氮肥运筹对粮饲兼用型玉米叶面积指数、叶重比、干物重、绝对生长率和相对生长率的影响,结果表明：随着生育的进程和氮肥施用量增加,玉米的叶面积指数和干物重均增加,抽雄期达最高值,其中优化施氮效果最佳;玉米叶重比从苗期到抽雄期呈下降趋势,苗期达到最高值。玉米的绝对生长率和相对生长率均为苗期-大口期达最高,大口-抽雄期下降,其中玉米的相对生长率下降速度较快。