Melatonin regulates antioxidative mechanisms in microalgaeChlamydomonas reinhardtii(Volvocales, Chlorophyceae)

Abstract

The role of melatonin (MLT) in micro-and macroalgae is the subject of continuous discussion. In eukaryotic unicellular organisms, the physiological role of MLT seems to differ from those of higher plants and mammals. Experimental data on the role of MLT in algae suggest that it acts mainly as an antioxidant. In the present study, the physiological role of MLT in phototrophic organisms was studied by measuring its effects on periodically controlled processes (cell division and HSP70B expression) as well as mechanisms involved in oxidative stress protection (carotenoids, FeSOD and MnSOD expression). The presence of MLT in Chlamydomonas reinhardtii was assessed and quantified using analytical thin-layer chromatography followed by fluorescence measurements. These data reveal that photoperiod had a significant influence on the processes and mechanisms studied in C. reinhardtii. Moreover, MLT had the greatest impact on C. reinhardtii under conditions promoting photo-oxidative stress. Addition of MLT to the growth medium down-regulated carotenoid content and the expression of FeSOD and MnSOD. These results support the idea that MLT has a physiological role as a direct and indirect antioxidant agent.

Melatonin: A Multifunctional Molecule That Triggers Defense Responses against High Light and Nitrogen Starvation Stress in Haematococcus pluvialis

“…The results are similar to those of a previous study. The addition of melatonin did not promote cell growth of C. reinhardtii under long day conditions . Notably, we observed that exogenous melatonin significantly enhanced the content of astaxanthin under nitrogen starvation and photoinduction by 2.25-fold compared to the control (Figure B).…”

“…The addition of melatonin did not promote cell growth of C. reinhardtii under long day conditions. 38 Notably, we observed that exogenous melatonin significantly enhanced the content of astaxanthin under nitrogen starvation and photoinduction by 2.25-fold compared to the control (Figure 1B). This indicates that melatonin enhanced the accumulation of astaxanthin in H. pluvialis in to stressful conditions.…”

Melatonin: A versatile tool for sustaining agricultural productivity and improving food security

“…Further to higher plants, the effect of exogenously applied melatonin has also been studied in algae, which are a rich source of biopharmaceutical compounds, have high nutritional value, and represent major feedstock due to their high growth rate and high sugar contents (Bruhn et al 2011). For example, research with C. reinhardtii revealed that exogenous application of melatonin resulted in the suppression of FeSOD and MnSOD enzymatic antioxidants under conditions of photo-oxidative stress (Tal, Malkiel, Sinam, Harel & Haim 2015). In a more recent study, melatonin application in H. pluvialis led to increased astaxanthin biosynthesis and improved tolerance to limited nitrogen and high light conditions (Ding et al 2018).…”

Revisiting algal lipids and cellular stress-causing strategies for ameliorating the productivity of suitable lipids of microalgae for biofuel applications

“…To access and understand photoperiodism, the estimation of mRNA expression of heat shock protein HSP70B, Mn-superoxide dismutase MnSOD, Fe-superoxide dismutase FeSOD, and carotenoid have been done along with the cell division pattern, which is also associated with the circadian rhythm. 182 This melatonin was firstly used as an enhancer of astaxanthin biosynthesis in low-light and nitrogen-deprived conditions as a response to stressed conditions; the interaction of melatonin with the secondary messenger (nitric oxide and salicylic acid) was also observed along with the exploration of fatty acids. Fatty acids increase to the highest level of about 15.32 ± 0.04% of DCW in Haematococcus pluvialis .…”