Raman Spectroscopic Analysis of a Desert Cyanobacterium Nostoc sp. in Response to UVB Radiation

Abstract

Cyanobacteria are capable of tolerating environmental extremes. To survive in extreme environments, cyanobacteria have developed the capability to adapt to a variety of stresses. For example, cyanobacteria have adopted a number of strategies with which to survive UV stress, including expression of UV-screening pigments and antioxidant systems. We have previously shown that several antioxidants are significantly expressed in Nostoc sp. by UVB irradiation. We report here that the content of UV-responsive biomarkers such as b-carotene and scytonemin can be easily detected by Fourier transform Raman spectroscopy with use of a small sample size and that the content of b-carotene is dependant on the UVB intensity and exposure time. Our results indicate that Raman spectroscopy may be a helpful tool to analyze UV-protective molecules of cyanobacterium in astrobiological studies without access to large sample sizes and complicated extractions, which are needed by other analytical techniques such as high-performance liquid chromatography and mass spectrometry.

CARS microscopy of scytonemin in cyanobacteria Nostoc commune

“…The surface layer absorbs higher amounts of solar radiation and potentially could have more pigments compared with deeper layers of colony. Moreover, even when probing a sample of a small size using Raman microspectroscopy, the information could be lost due to superposition of signals from all pigments presented in algae, so the signal of scytonemin may be suppressed, for instance, by the signal of carotenes . The scanning microscopy with high spatial (3D) resolution is more effective to determine the localization of a certain pigment in the cell .…”

Toxicological effects of nanometer titanium dioxide (nano-TiO2) on Chlamydomonas reinhardtii

“…Because stress can increase ROS production (Wang et al, 2008b), this results in an increase in the chl a/b ratio may be involved to ROS attack. For carotenoids, it is another matter, since carotenoid is effective quenchers of tripletstate photosensitizers, singlet oxygen, and peroxy radicals (Wang et al, 2010), so algal cells use it to extinguish ROS from photochemical reaction with TiO 2 , and algal cells also synthesis compensatively carotenoid as an adaptation. Similar phenomena occur to various metal stresses in algae, which showed that carotenoid synthesis increase as respond to quench ROS caused by heavy metals (Bossuyt and Janssen, 2004;Nikookar et al, 2005).…”

Damage to DNA caused by UV-B radiation in the desert cyanobacterium Scytonema javanicum and the effects of exogenous chemicals on the process

“…We have found that photosynthetic activity and dsDNA content decrease sharply in the beginning of irradiation, while decrease smoothly after 2 h when there is a peak of scytonemin content in Nostoc sp. (Wang et al, 2010), which implied that scytonemin might play a protective role in this stage, and thus increase SOD activity in S. javanicum (Fig. 5a).…”