bims-polyam 2021-02-28 papers

Issue of 2021–02–28
three papers selected by
Sebastian J. Hofer, University of Graz

J Plant Physiol. 2021 Feb 15. pii: S0176-1617(21)00026-2. [Epub ahead of print]258-259 153387

Effect of cold stress on polyamine metabolism and antioxidant responses in chickpea.

Saeed Amini, Reza Maali-Amiri, Seyyedeh-Sanam Kazemi-Shahandashti, Miguel López-Gómez, Behzad Sadeghzadeh, Ahmad Sobhani-Najafabadi, Khalil Kariman.

Metabolic and genomic characteristics of polyamines (PAs) may be associated with the induction of cold tolerance (CT) responses in plants. Characteristics of PAs encoding genes in chickpea (Cicer arietinum L.) and their function under cold stress (CS) are currently unknown. In this study, the potential role of PAs along with the antioxidative defense systems were assessed in two chickpea genotypes (Sel96th11439, cold-tolerant and ILC533, cold-sensitive) under CS conditions. Six days after exposure to CS, the leaf H2O2 content and electrolyte leakage index increased in the sensitive genotype by 47.7 and 59 %, respectively, while these values decreased or remained unchanged, respectively, in the tolerant genotype. In tolerant genotype, the enhanced activity of superoxide dismutase (SOD) (by 50 %) was accompanied by unchanged activities of ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase (CAT) as well as the accumulation of glutathione (GSH) (by 43 %) on the sixth day of CS. Higher levels of putrescine (Put) (322 %), spermidine (Spd) (45 %), spermine (Spm) (69 %) and the highest ratio of Put/(Spd + Spm) were observed in tolerant genotype compared to the sensitive one on the sixth day of CS. Gamma-aminobutyric acid (GABA) accumulation was 74 % higher in tolerant genotype compared to the sensitive one on the sixth day of CS. During CS, the activity of diamine oxidase (DAO) and polyamine oxidase (PAO) increased in tolerant (by 3.02- and 2.46-fold) and sensitive (by 2.51- and 2.8-fold) genotypes, respectively, in comparison with the respective non-stressed plants (normal conditions). The highest activity of DAO and PAO in the tolerant genotype was accompanied by PAs decomposition and a peak in GABA content on the sixth day of CS. The analysis of chickpea genome revealed the presence of five PAs biosynthetic genes, their chromosomal locations, and cis-regulatory elements. A significant increase in transcript levels of arginine decarboxylase (ADC) (24.26- and 7.96-fold), spermidine synthase 1 (SPDS1) (3.03- and 1.53-fold), SPDS2 (5.5- and 1.62-fold) and spermine synthase (SPMS) (3.92- and 1.65-fold) genes was detected in tolerant and sensitive genotypes, respectively, whereas the expression of ornithine decarboxylase (ODC) genes decreased significantly under CS conditions in both genotypes. Leaf chlorophyll and carotenoid contents exhibited declining trends in the sensitive genotype, while these photosynthetic pigments were stable in the tolerant genotype due to the superior performance of defensive processes under CS conditions. Overall, these results suggested the specific roles of putative PAs genes and PAs metabolism in development of effective CT responses in chickpea.

Keywords: Chickpea; Cold tolerance; Gene expression; Metabolic responses; Oxidative stress; Polyamines

DOI: https://doi.org/10.1016/j.jplph.2021.153387

Nucl Med Biol. 2021 Feb 14. pii: S0969-8051(21)00029-9. [Epub ahead of print]94-95 98-105

Radiosynthesis and evaluation of N5-(2-18F-fluoropropanyl) ornithine as a potential agent for tumor PET imaging.

Hongliang Wang, Qinan Zhao, Weixuan Dong, Liu Yang, Keyi Lu, Xiaoshan Guo, Haiyan Liu, Hua Wei, Yan Cheng, Zhifang Wu, Sijin Li.

OBJECTIVE: Studies have confirmed that tumorigenesis is related to an imbalance of polyamine metabolism and over-expression of oncogenes resulting in the up-regulation of ornithine decarboxylase (ODC, the first rate-limiting enzyme for regulating intracellular polyamines biosynthesis), which has become a target for anti-tumor therapy. In this study, an ornithine derivative, N5-(2-[18F]fluoropropionyl) ornithine (N5-[18F]FPO), has been prepared and its potential utility for tumor PET imaging evaluated.
METHODS: N5-[18F]FPO was successfully prepared via a nucleophilic fluorination reaction and a subsequent efficient deprotection step. The in vitro and in vivo stability were determined by HPLC conducted in fetal bovine serum, saline and rat urine. Cellular uptake studies were conducted in HepG2 cells and the biodistribution and micro-PET/CT imaging performed in normal ICR mice and three tumor-bearing mice models, respectively.
RESULTS: Total synthesis time of N5-[18F]FPO was about 80 min with a radiochemical yield of 15% ± 6% (uncorrected, based on 18F-, n = 6) and a high radiochemical stability can be seen in vitro and vivo. The N5-[18F]FPO exhibited fast uptake in HepG2 cells and the cellular uptake ability of N5-[18F]FPO can be inhibited by L-ornithine and DFMO, which indicated that the transport pathway of N5-[18F]FPO is similar to that of L-ornithine, interacting with ODC after being transported into the cell. The biodistribution and micro-PET/CT images demonstrate that N5-[18F]FPO was excreted by the urinary system, and excellent tumor visualization with high tumor-to-background ratios can be observed in the three tumor-bearing mice models studied.
CONCLUSION: All the above results suggest that N5-[18F]FPO has the potential to be a novel radiotracer for imaging ODC expression in solid tumors.

Keywords: Biological evaluation; N(5)-(2-[(18)F]fluoropropionyl) ornithine; Ornithine decarboxylase; Polyamine metabolism; Tumor PET imaging

DOI: https://doi.org/10.1016/j.nucmedbio.2021.02.002

Bioresour Technol. 2021 Feb 11. pii: S0960-8524(21)00166-8. [Epub ahead of print]328 124827

Metabolic pathways of Chlorella sp. cells induced by exogenous spermidine against nitric oxide damage from coal-fired flue gas.

Zhenyi Wang, Jun Cheng, Xiangdong Zhang, Lechong Chen, Jianzhong Liu.

To protect microalgae that are used for photosynthetic CO2 fixation against high NO concentrations from coal-fired flue gas, 500 μM exogenous spermidine was added into Chlorella sp. solution resulting in an elevation of biomass yield by 30.5% under 327 ppm NO. Metabolomics, proteomics and enzyme activities were analyzed, revealing three effects of spermidine on Chlorella sp. resistance to NO stress. First, spermidine induced NO fixation in amino acids and their metabolites, mainly in form of 5-oxoproline (1.51-fold), which occurred through intracellular conversion reactions between citrulline and arginine. Accordingly, cellular respiration was strengthened along with a weakened NO inhibition, which enhanced active transport with ATP consumption. Second, spermidine guarded Chlorella sp. against peroxidation damage by improving activity of antioxidant enzymes. Finally, it protected the photosynthetic system of Chlorella sp. by increasing abundance of related enzymes to enhance carbon fixation. Thus exogenous spermidine improved biomass production against NO environment.

Keywords: Metabolomics; Microalgae; Nitric oxide; Proteomics; Spermidine

DOI: https://doi.org/10.1016/j.biortech.2021.124827