Changes in free amino acids and polyamine levels in Satsuma leaves in response to Asian citrus psyllid infestation and water stress

The effects of biotic and abiotic stresses on changes in amino acids and polyamine levels in Satsuma orange （Citrus unshiu; cultivar Owari） leaves were inves- tigated. Asian citrus psyllids Diaphorina citri （Kuwayama） （ACP） infestation was used to induce biotic stress while a water deficit was imposed to induce abiotic stress. Potted trees were infested by placing 50 psyllids on 3 citrus leaves enclosed in nylon mesh bags for 5 d. A parallel set of plants were kept water stressed by maintaining the soil at 20% water holding capacity for 5 d. Levels of total free amino acids were higher in water stressed and ACP infested leaves. Polyamine putrescine increased in infested leaves but not in water stressed leaves. Proline was the most abundant amino acid and its levels significantly increased by both biotic and abiotic stresses. Proline levels in infested leaves were significantly higher than the water stressed leaves. Histidine, methionine, asparagine, arginine, serine, and leucine levels also increased significantly in infested leaves, but in water stressed leaves only leucine, methionine, and threonine increased. Levels of amino acids, such as tyrosine, isoleucine, phenylalanine, glutamic acid, and alanine, declined in infested leaves. Under water stress asparagine, phenylalanine, serine, and histidine also declined compared to controls. This indicates that while proteolysis occurred under both stresses, metabolic conversion of amino acids was different under the two stresses. In ACP infested leaves some amino acids may be used as feeding material and/or converted into secondary metabolites for defense.     

感染病毒的番茄花药发育过程中游离脯氨酸含量与花粉萌发率的变化(简报)

植株染病毒的番茄花药发育过程中游离脯氨酸积累开始较晚，任一花药发育时期花药中的游离脯氨酸含量均低于同一发育时期的健康植株，花粉萌发率也低。     

海南岛不同生态型槟榔主要营养成分含量变化的分析

本研究结果表明，分布在海南岛内４种生态型槟榔，其主要营养物质组成含量水平变化差异程序较为显著。总氨基酸组成中，以砂丘槟榔〉沟谷槟榔〉旱生槟榔〉滨海槟榔。而人体所必需，药效氨基酸组分仍以砂丘槟榔相对量值为最高。     

肽可以制成疫苗吗?

以合成肽为基础的新一代疫苗的可能性不断出现,尽管有希望,但前面的路还很长。 因为蛋白质具有比较刚性的结构(晶体学家使我们相信是这样的),所以没有理由预期裸露在蛋白质表面的小段氨基酸链会持有同一肽链游离于溶剂时所取的相同的构象。同样也没有理由预期抗游离肽而产生的抗体会识别含有这部分肽链的蛋白质。