Global and Comparative Proteome Analysis of Nitrogen-Stress Responsive Proteins in the Root, Stem and Leaf of Brassica napus

Nitrogen(N)is one of the basic nutrients and signals for plant development and deficiency of it would always limit the productions of crops in the field.Quantitative research on expression of N-stress responsive proteins on a proteome level remains elusive.In order to gain a deep insight into the proteins responding to nitrogen stress in rapeseed(Brassica napus L.),comparative proteomic analysis was performed to investigate changes of protein expression profiles from the root,stem and leaf under different N concentrations,respectively.More than 200 differential abundance proteins(DAPs)were detected and categorized into groups according to annotations,including“binding and catalytic activity”,“involved in primary metabolism and cellular processes”,“stress-response”and so on.Variation in chlorophyll(Chl)content and antioxidant activities further revealed that oxidative stress raised with the increase of N concentration.Bioinformatics analysis based on the expression level of total proteins suggested these DAPs might play important roles in adaptation to N-stress conditions.Generally,these results provides a new aspect into N-stress responding proteins in Brassica plants.

Regulation of nitrogen starvation responses by the alarmone(p)ppGpp in rice

Nitrogen is an essential macronutrient for all living organisms and is critical for crop productivity and quality.In higher plants,inorganic nitrogen is absorbed through roots and then assimilated into amino acids by the highly conserved glutamine synthetase/glutamine:2-oxoglutarate aminotransferase(GS/GOGAT)cycle.How nitrogen metabolism and nitrogen starvation responses of plants are regulated remains largely unknown.Previous studies revealed that mutations in the rice ABNORMAL CYTOKININ RESPONSE1(ABC1)gene encoding Fd-GOGAT cause a typical nitrogen deficiency syndrome.Here,we show that ARE2(for ABC1 REPRESSOR2)is a key regulator of nitrogen starvation responses in rice.The are2 mutations partially rescue the nitrogen-deficient phenotype of abc1 and the are2 mutants show enhanced tolerance to nitrogen deficiency,suggesting that ARE2 genetically interacts with ABC1/Fd-GOGAT.ARE2 encodes a chloroplast-localized Rel A/Spo T homolog protein that catalyzes the hydrolysis of guanosine pentaphosphate or tetraphosphate(p)pp Gpp,an alarmone regulating the stringent response in bacteria under nutritional stress conditions.The are2 mutants accumulate excessive amounts of(p)pp Gpp,which correlate with lower levels of photosynthetic proteins and higher amino acid levels.Collectively,these observations suggest that the alarmone(p)pp Gpp mediates nitrogen stress responses and may constitute a highly conserved mechanism from bacteria to plants.

Wastewater-nitrogen removal using polylactic acid/starch as carbon source： Optimization of operating parameters using response surface methodology

Nitrogen removal from ammonium-containing wastewater was conducted using polylactic acid （PLA）/ starch blends as carbon source and carrier for fimctional bacteria. The exclusive and interactive influences of operating parameters （i.e., temperature, pH, stirring rate, and PLA-to-starch ratio （PLA proportion）） on nitrification （Y1）, denitrification （Y2）, and COD release rates （Y3） were investigated through response surface methodology. Experimental results indicated that nitrogen removal could be successfully achieved in the PLA/starch blends through simultaneous mtnncatlon anti clenltnncatlon. The carbon release rate of the blends was controllable. The sensitivity of Y1, Y2, and Y3 to different operating parameters also differed. The sequence for each response was as follows： for Y1, pH 〉 stirring rate 〉 PLA proportion 〉 temperature; for Y2, PH 〉 PLA proportion 〉.temperature.〉 stirring rate; and for Y3, stirring rate 〉pH 〉 PLA proportion 〉 temperature. In this study, the following optimum conditions were observed： temperature, 32.0℃; pH 7.7; stirring rate, 200.0 r · min^-1 and PLA proportion 0.4. Under these conditions Y1 Y2 and Y3 were 134.0 μg-N·g-blend^-1·h^-1, 160.9μg-N-g-blend^-1·h^-1, and 7.6 × 10^3 μg-O·g-blend^-1·h^-1, respectively. These results suggested that the PLA/starch blends may be an ideal packing material for nitrogen removal.

The RALF1-FERONIA complex interacts with and activates TOR signaling in response to low nutrients

Target of rapamycin(TOR)kinase is an evolutionarily conserved major regulator of nutrient metabolism and organismal growth in eukaryotes.In plants,nutrients are remobilized and reallocated between shoots and roots under low-nutrient conditions,and nitrogen and nitrogen-related nutrients(e.g.,amino acids)are key upstream signals leading to TOR activation in shoots under low-nutrient conditions.However,how these forms of nitrogen can be sensed to activate TOR in plants is still poorly understood.Here we report that the Arabidopsis receptor kinase FERON IA(FER)interacts with the TOR pathway to regulate nutrient(nitrogen and amino acid)signaling under low-nutrient conditions and exerts similar metabolic effects in response to nitrogen deficiency.We found that FER and its partner,RPM1-induced protein kinase(RIPK),interact with the TOR/RAPTOR complex to positively modulate TOR signaling activity.During this process,the receptor complex FER/RIPK phosphorylates the TOR complex component RAPTOR1B.The RALF1 peptide,a ligand of the FER/RIPK receptor complex,increases TOR activation in the young leaf by enhancing FER-TOR interactions,leading to promotion of true leaf growth in Arabidopsis under lownutrient conditions.Furthermore,we showed that specific amino acids(e.g.,Gin,Asp,and Gly)promote true leaf growth under nitrogen-deficient conditions via the FER-TOR axis.Collectively,our study reveals a mechanism by which the RALF1-FER pathway activates TOR in the plant adaptive response to low nutrients and suggests that plants prioritize nutritional stress response over RALF1-mediated inhibition of cell growth under low-nutrient conditions.

Injectable reactive oxygen and nitrogen species-controlling hydrogels for tissue regeneration:current status and future perspectives

The dual role of reactive oxygen and nitrogen species(RONS)in physiological and pathological processes in biological systems has been widely reported.It has been recently suggested that the regulation of RONS levels under physiological and pathological conditions is a potential therapy to promote health and treat diseases,respectively.Injectable hydrogels have been emerging as promising biomaterials for RONS-related biomedical applications owing to their excellent biocompatibility,three-dimensional and extracellular matrix-mimicking structures,tunable properties and easy functionalization.These hydrogels have been developed as advanced injectable platforms for locally generating or scavenging RONS,depending on the specific conditions of the target disease.In this review article,the design principles and mechanism by which RONS are generated/scavenged from hydrogels are outlined alongside a discussion of their in vitro and in vivo evaluations.Additionally,we highlight the advantages and recent developments of these injectable RONS-controlling hydrogels for regenerativemedicines and tissue engineering applications.