Isolate-specific effects of ultraviolet radiation on photosynthesis, growth and mycosporine-like amino acids in the microbial mat-forming cyanobacterium Microcoleus chthonoplastes

Abstract

Microcoleus chthonoplastes constitutes one of the dominant microorganisms in intertidal microbial mat communities. In the laboratory, the eVects of repeated daily exposure to ultraviolet radiation (16:8 light:dark cycle) was investigated in unicyanobacterial cultures isolated from three diVerent localities (Baltic Sea = WW6; North Sea = STO and Brittany = BRE). Photosynthesis and growth were measured in time series (12-15 days) while UV-absorbing mycosporine-like amino acids (MAAs) and cellular integrity were determined after 12 and 3 days exposure to three radiation treatments [PAR (22 mol photon m ¡2 s ¡1 ) = P; PAR + UV-A (8 W m ¡2

In vivo growth fluorometry: accuracy and limits of microalgal growth rate measurements in ecophysiological investigations

“…These cells had a much higher cell-specific chl a content (Table 2) and adhered very easily to the bottom of the petri dish. Even though the present excitation wavelength of 470 nm is not optimal for Cyanobacteria, growth rates of C. chthonoplastes could be determined at low to intermediate abundances in particular for slow-growing isolates and at high excitation irradiances (Pattanaik et al 2008).…”

“…In the context of ongoing population and species extinction due to anthropologic changes of ecosystems, the description of physiological niches is imperative to explain species occurrence (hindsight) and propagation or displacement (forecast). So far, the method of in vivo growth fluorometry has been successfully applied to Cyanobacteria (Garcia-Pichel et al 1998, Pattanaik et al 2008 …”

Inhibition of photosynthesis by UV-B exposure and its repair in the bloom-forming cyanobacterium Microcystis aeruginosa

“…It is found that enhanced UV-B can affect cyanobacterial growth, photosynthesis, pigments, and morphology, though different responses are observed in different species treated with different UV doses (Jiang and Qiu 2005;Wu et al 2005;Rath and Adhikary 2007;Pattanaik et al 2008). On the other hand, cyanobacteria are the oldest autotrophic inhabitants of the planet and have evolved efficient mechanisms to cope with the stress of UV exposure (Castenholz and Garcia-Pichel 2000).…”

The seaweed Prasiola crispa (Chlorophyta) neutralizes toxic effects of Bothrops jararacussu snake venom

“…However, inhibitory activity against in vitro (proteolytic and coagulating) or in vivo (hemorrhagic, edematogenic, and lethality) activities of B. jararacussu venom is being presented for the first time. in such unfavorable biotic and abiotic conditions, they synthesize a variety of molecules with different biological and pharmacological properties (Pattanaik et al 2008;Pereira et al 2009), but an antivenom effect has not been described before. The proteolytic, coagulant, and hemorrhagic activities of venoms are caused by proteases, called serine protease and metalloproteinases.…”

“…One of these strategies is the production of photoprotective molecules such as mycosporine-like amino acids (MMAs), scytonemim secreted by cyanobacteria and flavonoids secreted by plants (Pereira et al 2009). MAAs are the strongest UVR-absorbing compounds in nature (Pattanaik et al 2008;Carreto and Carignan 2011), and a molecule (called Prasiolin) with such activity has been isolated from Prasiola calophylla and its chemical structure elucidated (Hartmann et al 2016). The adhesive property of the genus Prasiola has been described before, demonstrating a potential biotechnological application (Pereira et al 2009), but no study related to the biological or pharmacological effects of P. crispa has been performed previously.…”