Phosphorylation regulation of nitrogen,phosphorus,and potassium uptake systems in plants

The uptake of ammonium,nitrate,phosphorus,and potassium ions by roots is mediated by specific ion transporter or channel proteins,and protein phosphorylation regulation events occurring on these proteins and their regulators determine their ultimate activity.Elucidating the mechanism by which protein phosphorylation modification regulates nutrient uptake will advance plant breeding for high nutrientuse efficiency.In this review,it is concluded that the root nutrient absorption system is composed of several,but not all,members of a specific ion transporter or channel family.Under nutrient-starvation conditions,protein phosphorylation-based regulation of these proteins and associated transcription factors increases ion transporter-or channel-mediated nutrient uptake capacity via direct function activity enhancement,allowing more protein trafficking to the plasma membrane,by strengthening the interaction of transporters and channels with partner proteins,by increasing their protein stability,and by transcriptional activation.Under excessive nutrient conditions,protein phosphorylation-based regulation suppresses nutrient uptake by reversing these processes.Strengthening phosphorylation regulation items that increase nutrient absorption and weakening phosphorylation modification items that are not conducive to nutrient absorption show potential as strategies for increasing nutrient use efficiency.

劳动力市场需要什么样的教师?——基于网络招聘信息的挖掘与分析

过去十多年,劳动力市场招聘模式已迅速从线下转向线上。招聘单位通过招聘网站提交并记录的招聘信息,为研究教师劳动力市场的需求提供了新的数据资料。在这一背景下,应用网络爬虫技术爬取并清洗得到招聘网站上六万多条教师招聘信息,以此为基础数据,对教师劳动力市场的技能或特征需求进行了研究,主要发现包括:一是中学教师职位对学历、专业技能、教师资格证等的要求依次高于小学和幼儿教师职位,但幼儿教师职位对社会情感技能和工作经验的需求依次高于小学和中学教师职位。二是社会情感技能被特别强调,尤其是对幼师职位来说。三是劳动力市场对教师的学习能力、创新思维、批判思维和问题解决等高阶认知技能的需求很低。

Arabidopsis under ammonium over-supply: Characteristics of ammonium toxicity in relation to the activity of ammonium transporters

Because of highly intensive farming practices, crop plants could suffer relatively long terms of ammonium(NH4+) excess stress introduced by overdose application of nitrogen fertilizers. However, the lack of sufficient understanding of plant responses to NH4+excess stress impairs the detection of effective solutions to this problem. The present work examined the biological influences of over-supplied NH4+in Arabidopsis thaliana using two mutant lines each with an ammonium transporter(AMT) gene(AtAMT1;1 or AtAMT1;3) knocked out. Our results indicated that lacking one of the major components of root NH4+-absorbing systems significantly alleviated the toxicity effects on Arabidopsis plants by reducing the accumulation of free NH4+, suggesting that persistent absorption of NH4+through AMT was the main cause of excessive accumulation of free NH4+in the plants. Shading treatment led to a reduced transpirational driving force and thereby constrained the accumulation of toxic NH4+in the plants, finally resulting in higher NH4+-promoted growth in the wild type(WT). Under the shading treatment, the amt1;1 and amt1;3 mutant plants acquired insufficient NH4+and showed reduced growth when compared with the WT. Furthermore, the foliar application of sucrose notably alleviated the inhibitory effects on plant growth in the WT but had no effect on either the amt1;1 or amt1;3 mutant plants, indicating that carbon scarcity associated with NH4+excess is probably a major cause of NH4+toxicity in plants. Accordingly,increasing carbon source could be a potentially effective approach that alleviates the inhibition caused by NH4+excess and increases nitrogen use efficiency under NH4+over-supply.