CO2对离体欧芹叶片中蛋白质代谢的影响

以离体欧芹叶片为实验系统,研究了ＣＯ２对叶片中蛋白质降解的影响。对离体欧芹叶片中游离氨基酸含量及可溶蛋白含量的分析结果表明：ＣＯ２具有抑制离体欧芹叶片中蛋白质降解的作用,这为进一步了解ＣＯ２延缓叶片衰老的作用机理很有意义。     

dr and spr/sr mutations of Chlamydomonas reinhardtii affecting D1 protein function and synthesis define two independent steps leading to chronic photoinhibition and confer differential fitness

The effects of introduced chloroplast gene mutations affecting D1 synthesis, turnover and function on photosynthesis, growth and competitive ability were examined in autotrophic cultures of Chlamydomonas reinhardtii (Chlorophyta) adapted to low or high irradiance. Few discernible effects were evident when the mutants were grown in low light (LL, 70 μmol m^?2 s^?1). The herbicide-resistant psbA mutation Ser²⁶⁴→ Ala (dr) slowed electron transfer and accelerated D1 degradation in cells grown under high light (HL, 600 μmol m^?2 s^?1). The maximum rate of light-and CO₂-saturated photosynthesis, cell growth rate and competitive ability in the dr mutant were reduced compared to wild type under HL. However, the wild-type rate of D1 synthesis in dr was adequate to compensate for accelerated D1 degradation. 16S rRNA mutations conferring resistance to streptomycin and spectinomycin (spr/sr) that altered chloroplast ribosome structure and assembly were used to inhibit chloroplast protein synthesis. In spr/sr cells grown under HL, D1 synthesis was reduced by 40–60% compared to wild type and D1 degradation was accelerated, leading to a 4-fold reduction in D1 pool size. The reduced D1 levels were accompanied by an elevation of F_o and a decline in F_v/F_m, quantum yield and maximum rate of CO₂-saturated photosynthesis. Chemostat experiments showed that the growth rate and competitive ability of spr/sr were reduced against both wild type and dr.     

Differential expression of miRNAs and their target genes in senescing leaves and siliques: insights from deep sequencing of small RNAs and cleaved target RNAs

MicroRNAs (miRNAs) are a class of small RNAs, which typically function by guiding cleavage of target mRNAs. They are known to play roles in a variety of plant processes including development, responses to environmental stresses and senescence. To identify senescence regulation of miRNAs in Arabidopsis thaliana, eight small RNA libraries were constructed and sequenced at four different stages of development and senescence from both leaves and siliques, resulting in more than 200 million genome‐matched sequences. Parallel analysis of RNA ends libraries, which enable the large‐scale examination of miRNA‐guided cleavage products, were constructed and sequenced, resulting in over 750 million genome‐matched sequences. These large datasets led to the identification a new senescence‐inducible small RNA locus, as well as new regulation of known miRNAs and their target genes during senescence, many of which have established roles in nutrient responsiveness and cell structural integrity. In keeping with remobilization of nutrients thought to occur during senescence, many miRNAs and targets had opposite expression pattern changes between leaf and silique tissues during the progression of senescence. Taken together, these findings highlight the integral role that miRNAs may play in the remobilization of resources and alteration of cellular structure that is known to occur in senescence.     

CO_2对离体欧芹叶片中蛋白质代谢的影响

以离体欧芹叶片为实验系统 ,研究了CO2 对叶片中蛋白质降解的影响。对离体欧芹叶片中游离氨基酸含量及可溶蛋白含量的分析结果表明 :CO2 具有抑制离体欧芹叶片中蛋白质降解的作用 ,这为进一步了解CO2 延缓叶片衰老的作用机理很有意义。     

CO2对离体欧芹叶片中蛋白质代谢的影响

以离体欧芹叶片为实验系统,研究了CO2对叶片中蛋白质降解的影响。对离体欧芹叶片中游离氨基酸含量及可溶蛋白含量的分析结果表明:CO2具有抑制离体欧芹叶片中蛋白质降解的作用,这为进一步了解CO2延缓叶片衰老的作用机理很有意义。