Short-Term UV-B and UV-C Radiations Preferentially Decrease Spermidine Contents and Arginine Decarboxylase Transcript Levels of Synechocystis sp. PCC 6803

Abstract

To investigate the short term effect of ultraviolet (UV) radiations on changes in pigments and polyamine contents, Synechocystis sp. PCC 6803 cells after exposure to UV-radiation were extracted by dimethylformamide and perchloric acid for pigments and polyamines determination, respectively. Cell growth was slightly decreased after 1 h exposure to UV-A and UV-B radiations. UV-C had little effect on cell growth despite the decrease of photosynthetic rate by about 18%. UV-A and UV-B decreased the contents of chlorophyll a and carotenoids whereas UV-C decreased chlorophyll a but had no effect on carotenoids. Spermidine contents were unaffected by UV-A, in contrast to the reduction of 25 and 50% by UV-B and UV-C, respectively. All three types of UV-radiation particularly reduced perchloric acid-insoluble spermidine. Importantly, putrescine and spermine which accounted for less than 1% of intracellular polyamines were increased by about three- to eight-fold by UV-B and UV-C, respectively. The changes in polyamines contents by UV-B and UV-C were consistent with the changes in transcript levels of arginine decarboxylase mRNA, but not with the protein levels. The decrease in the transcripts of adc2 but not adc1 was observed with UV-B and UV-C treatments.

Polyamines and abiotic stress in plants: a complex relationship1

“…Typically when cellular PA contents are up, their catabolism also increases, the levels of H 2 O 2 increase, and various ROS as well as the antioxidant systems (enzymes and metabolites) are also up, hence their roles in preventing damage from stress are beneficial as well as deleterious. The role of PAs in augmenting antioxidant based defense systems to impart tolerance against heavy metals, UV and other stresses that are potent inducers of superoxide molecules causing oxidative damage to the living cells have been reported in several studies (Bouchereau et al, 1999; Groppa et al, 2007; Thangavel et al, 2007; Mapelli et al, 2008; Rakitin et al, 2009; Jantaro et al, 2011; Pothipongsa et al, 2012; Chmielowska-Bąk et al, 2013; Mandal et al, 2013; Scoccianti et al, 2013). This is consistent with the diverse roles of PAs including the fact that an increase in cellular PA titers contributes to both sides of the ROS-antioxidant equation under conditions of stress.…”

Regulation of polyamine metabolism in Pyropia cinnamomea (W.A. Nelson), an important mechanism for reducing UV‐B‐induced oxidative damage

“…Jantaro et al. () showed that UV‐B and UV‐C can reduce total PA levels by 25%–50% in the cyanobacterium Synechocystis sp., while stimulating an increase in PUT and SPM 3‐ to 8‐fold, respectively. Concurrently, total ADC gene expression decreased, but ADC 1 gene expression and ADC protein levels increased.…”

Polyamines in macroalgae: advances and future perspectives

“…In this case, UV‐A radiation induced the expression of the ADC1 gene, indicating that ADC1 is the main gene involved in UV‐A protection by increasing the amount of free PAs (Jantaro et al. ).…”

“…At the same time, ADC mRNA decreased, while ADC activity did not change (Jantaro et al. ). Under closer observation, it became clear that the induction of transcription depended upon the wavelength of the UV radiation.…”

“…) in a macroalga and the ADC1 gene (Jantaro et al. ) microalga, have been examined to date. Homologs of the ACL5 gene, involved in thermo SPM synthesis have also been reported for algae (Takano et al.…”