Complementary UV-Absorption of Mycosporine-like Amino Acids and Scytonemin is Responsible for the UV-Insensitivity of Photosynthesis in Nostoc flagelliforme

Mycosporine-like amino acids (MAAs) and scytonemin are UV-screening compounds that have presumably appeared early in the history of life and are widespread in cyanobacteria. Natural colonies of the UV-insensitive Nostoc flagelliforme were found to be especially rich in MAAs (32.1 mg g DW−1), concentrated in the glycan sheath together with scytonemin. MAAs are present in the form of oligosaccharide-linked molecules. Photosystem II activity, measured using PAM fluorescence and oxygen evolution, was used as a most sensitive physiological parameter to analyse the effectiveness of UV-protection. Laboratory experiments were performed under controlled conditions with a simulated solar radiation specifically deprived of UV-wavebands with cut-off filters (295, 305, 320, 345 and 395 nm). The UV-insensitivity of N. flagelliforme was found to cover the whole UV-A (315–400 nm) and UV-B (280–320 nm) range and is almost certainly due to the complementary UV-absorption of MAAs and scytonemin. The experimental approach used is proposed to be suitable for the comparison of the UV-protection ability in organisms that differ in their complement of UV-sunscreen compounds. Furthermore, this study performed with a genuinely terrestrial organism points to the relevance of marine photoprotective compounds for life on Earth, especially for the colonization of terrestrial environments

Cyanobacterial metabolites as a source of sunscreens and moisturizers: a comparison with current synthetic compounds

The recognition that ultraviolet radiation has harmful effects on the skin has led to the commercial development of inorganic and synthetic organic UV filters that can reduce the negative effects of exposure to sunlight. In addition, moisturizing chemicals are extensively used in personal care products to improve the ability of skin to retain water. Whilst current UV filter and moisturizing chemicals have clear beneficial qualities, they may also have adverse effects such as contact sensitivity, oestrogenicity and even tumorigenic effects on human skin. Furthermore, the accumulation of these chemicals in the aquatic environment could be potentially harmful. Consequently, there is interest in exploiting safer alternatives derived from biological sources, especially from photosynthetic organisms such as cyanobacteria which have developed mechanisms for coping with high UV irradiation and desiccation. In order to overcome the detrimental effects of UV radiation, these microorganisms produce UV screening compounds such as mycosporine-like amino acids and scytonemin, which are good candidates as alternatives to current synthetic UV filters. In addition, extracellular substances produced by some extremophilic species living in hyper-arid habitats have a high water retention capacity and could be used in cosmetic products as moisturizers. In this review, we present an overview of the literature describing the potential of cyanobacterial metabolites as an alternative source for sunscreens and moisturizers

Maltese microalgae and global climate variability

The biodiversity of cyanobacteria and microalgae growing in terrestrial and marine habitats around the Maltese islands is currently being investigated, as limited knowledge exists about the phototrophic microorganisms inhabiting this geographical area. New strains of the genera Oculatella, Albertania, Nodosilinea, Nostoc, Lyngbya, Oscillatoria, Calothrix and Jenufa have been recorded recently. Since the phototrophic microbial biodiversity is currently largely unknown, there is an imminent risk of undescribed microorganisms being lost as a result of changes in microbial community structures due to global climate variability (GCV). We describe a six-month experiment to assess the effects of GCV on two Maltese microorganisms, the filamentous heterocytous cyanobacterial Nostoc strain AD0303 and a coccal microalgal Jenufa strain AD0402. Each strain was cultured under environmental conditions associated with GCV; a temperature (T) of 26 C, enhanced ultraviolet radiation (UVR) and an increased CO2 concentration. Elevated T stimulated growth and biomass accumulation of Nostoc AD0303, whereas growth of Jenufa AD0402 was partially inhibited. Increased UVR had the most prominent effect on cellular morphology. Nostoc AD0303 presented as aggregated filaments, whereas Jenufa AD0402 exhibited thicker cell walls. These UV-protecting mechanisms allowed both strains to accumulate biomass at a significantly higher rate than the control. An increase in CO2 concentration resulted in inhibition of growth in Jenufa AD0402 and bleaching of filaments in Nostoc AD0303, both leading to culture death. A lower CO2 concentration and re-introduction of air subsequently allowed Jenufa AD0402 to grow. So far, this demonstrates that the effects imposed by climate variability are strain-specific, making changes at an ecosystem level difficult to predict.peer-reviewe

Revealing the potential of cyanobacteria in cosmetics and cosmeceuticals — A new bioactive approach

The growing concern over appearance, health and aging has driven the exploration for cosmetics based on natural sources. Alongside with plants, algae and eukaryotic microalgae, cyanobacteria have been explored for the isolation of compounds with potential application in the cosmetic and cosmeceutical field. The long evolutionary history of cyanobacteria and exposure to environmental stress conditions seems to be the basis for the production of compounds with protective roles against external factors, such as desiccation, UV radiation and salinity. The production of exopolysaccharides, UV-protectors such as mycrosporine like amino acids and scytonemin, and antioxidant and anti-inflammatory compounds, by a wide range of cyanobacteria genera, coupled with a growing demand for natural origin products, places these organisms in the investigation line linked to cosmetics. The low nutritional requirements for large scale culture and the possibility to increase compounds production by manipulating culture conditions, also highlights the importance of these organisms as an alternative and a promising source for cosmetics based on nature. In this review, a general overview of the state of the art regarding the potential of cyanobacteria for the cosmetic and cosmeceutical industry is provided, emphasizing the main properties required in skin care formulations.info:eu-repo/semantics/publishedVersio

Cyanobacterial metabolites as a source of sunscreens and moisturizers: a comparison with current synthetic compounds

The recognition of the harmful effects of ultraviolet radiation on the skin has led to the commercial development of inorganic and synthetic organic UV filters that can attenuate the negative effects of sunlight exposure. In addition, chemical moisturizers are extensively used in cosmetic products to improve the ability of skin to retain water. Whilst these chemicals have clear beneficial qualities, they may also have adverse effects such as contact sensitivity, oestrogenicity and even tumorigenic effects on human skin. Furthermore, the accumulation of such chemicals in the aquatic environment could be potentially harmful. Consequently, there is interest in exploiting safer alternatives derived from biological sources, especially from photosynthetic organisms such as cyanobacteria that have developed mechanisms for coping with high UV irradiation and desiccation. In order to overcome the detrimental effects of UV radiation, these microorganisms produce UV screening compounds such as mycosporine-like amino acids and scytonemin, which are good candidates as alternatives to current synthetic UV filters. In addition, extracellular substances produced by some extremophilic species living in hyper-arid habitats have a high water retention capacity and could be used in cosmetic products as moisturizers. In this review, we present an overview of the literature describing the potential of cyanobacterial metabolites as an alternative source for sunscreens and moisturizers

Response of endolithic chroococcidiopsis strains from the polyextreme Atacama desert to light radiation

Cyanobacteria exposed to high solar radiation make use of a series of defense mechanisms, including avoidance, antioxidant systems, and the production of photoprotective compounds such as scytonemin. Two cyanobacterial strains of the genus Chroococcidiopsis from the Atacama Desert – which has one of the highest solar radiation levels on Earth- were examined to determine their capacity to protect themselves from direct photosynthetically active (PAR) and ultraviolet radiation (UVR): the UAM813 strain, originally isolated from a cryptoendolithic microhabitat within halite (NaCl), and UAM816 strain originally isolated from a chasmoendolithic microhabitat within calcite (CaCO3). The oxidative stress induced by exposure to PAR or UVR C PAR was determined to observe their short-term response, as were the long-term scytonemin production, changes in metabolic activity and ultrastructural damage induced. Both strains showed oxidative stress to both types of light radiation. The UAM813 strain showed a lower acclimation capacity than the UAM816 strain, showing an ever-increasing accumulation of reactive oxygen species (ROS) and a smaller accumulation of scytonemin. This would appear to reflect differences in the adaptation strategies followed to meet the demands of their different microhabitats.This study was supported by grant PGC2018-094076-B-I00 from MCIU/AEI (Spain) and FEDER (UE). MC was supported by grant BES 2014-069106 from the Spanish Ministry of Science and Innovation (MCINN).Peer reviewe

Caracterización morfoloecológica y de pigmentos de macrocolonias Nostoc de lagunas altoandinas del Perú

Caracteriza morfoecológicamente y a nivel de pigmentos las macrocolonias de Nostoc de lagunas altoandinas del Perú. Las macrocolonias recolectadas en La Libertad, Ayacucho y Ancash, fueron identificadas como N. sphaericum, N. parmeloides y N. zetterstedtii, respectivamente. Presentaron una complejidad de morfotipos y estadíos. En todas las muestras, tanto antes (0 h) y después de la exposición a radiación UV, se observaron concentraciones de compuestos absorbentes de radiación: clorofila-a, carotenoides, scitoneminas y aminoácidos tipo micosporinas (MAAs). Los cuales, aumentaron ante una exposición de radiación UV a corto plazo (6 h) y disminuyeron a largo plazo (20 h). N. zetterstedtii (Ancash) presentó las concentraciones más altas, para la clorofila-a los valores fueron de 14.74 μg.g-1 (0 h), 18.99 μg.g-1(6 h) y 10.08 μg.g-1(20 h); para los carotenos, 22.49 μg.g-1 (0 h), 38.29 μg.g-1(6 h) y 20.60 μg.g-1(20 h); para la scitonemina, 44.46 μg.g-1 (0 h), 83.77 μg.g-1(6 h) y 58.82 μg.g-1(20 h); y para los MAAs, 257.36 μg.g- 1, 487.65 μg.g-1 y 359.68 μg.g-1. N. parmeloides fue más sensible a las exposiciones de radiación UV y presentó lo valores más bajos de pigmentos, seguida de N. sphaericum. Además, se evidenció la capacidad de tolerancia hídrica para todas las muestras, siendo N. parmeloides, la que presentó menor tasa de desecación (80.35% de pérdida en 45 horas) y mayor tasa de hidratación (14.62% en 25 horas); y N. zetterstedtii, la que presentó un comportamiento más estable. Por lo tanto, la plasticidad fenotípica y las adaptaciones ecológicas, como la producción de pigmentos (scitoneminas y MAAs) y tolerancia a la desecación (congelamiento y descongelamiento) de las especies estudiadas, demuestran que son especies complejas y extremófilas que habitan en los ambientes altoandinos.Perú. Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica (CONCYTEC). Fondo Nacional de Desarrollo Científico, Tecnológico y de Innovación Tecnológica (FONDECYT), CONV N°144-2017-FONDECYT

Mycosporine-Like Amino Acids and Marine Toxins - The Common and the Different

Marine microorganisms harbor a multitude of secondary metabolites. Among these are toxins of different chemical classes as well as the UV-protective mycosporine-like amino acids (MAAs). The latter form a group of water-soluble, low molecular-weight (generally < 400) compounds composed of either an aminocyclohexenone or an aminocyclohexenimine ring, carrying amino acid or amino alcohol substituents. So far there has been no report of toxicity in MAAs but nevertheless there are some features they have in common with marine toxins. Among the organisms producing MAAs are cyanobacteria, dinoflagellates and diatoms that also synthesize toxins. As in cyclic peptide toxins found in cyanobacteria, amino acids are the main building blocks of MAAs. Both, MAAs and some marine toxins are transferred to other organisms e.g. via the food chains, and chemical modifications can take place in secondary consumers. In contrast to algal toxins, the physiological role of MAAs is clearly the protection from harmful UV radiation by physical screening. However, other roles, e.g. as osmolytes and antioxidants, are also considered. In this paper the common characteristics of MAAs and marine toxins are discussed as well as the differences

Multifunctional sunscreen pigments from the terrestrial cyanobacterium Nostoc commune

13301甲第3972号博士（理学）金沢大学博士論文本文Full 以下に掲載：Marine Drugs 11(9) pp.3124-3154 2013. MDPI. 共著者：Ehsan Nazifi, Naoki Wada, Minami Yamaba, Tomoya Asano, Takumi Nishiuchi, Seiichi Matsugo, Toshio Sakamot

The extracellular-matrix-retaining cyanobacterium Nostoc verrucosum accumulates trehalose, but is sensitive to desiccation

金沢大学理工研究域自然システム学系Orexin-A and orexin-B are hypothalamic neuropeptides that play critical roles in the maintenance of wakefulness. Intracerebroventricular (ICV) administration of orexin-A has been shown to promote wakefulness and suppress both rapid eye movement (REM) sleep and non-REM (NREM) sleep through the orexin receptor-1 (OX1R) and orexin receptor-2 (OX2R). Here, we elucidated the differential roles of orexin receptors in the regulation of sleep and wakefulness by comparing the effects of ICV orexin-A administration in wild-type, OX1R, and OX2R mice. The effects of orexin-A on wakefulness and NREM sleep were significantly attenuated in both knock-out mice as compared with wild-type mice, with substantially larger attenuation in OX2R mice than in OX1R mice. These results suggest that although the OX2R-mediated pathway has a pivotal role in the promotion of wakefulness, OX1R also plays additional roles in promoting arousal. In contrast, suppression of REM sleep by orexin-A administration was slightly and similarly attenuated in both OX1R and OX2R mice, suggesting a comparable contribution of the two receptors to REM sleep suppression. Histological studies demonstrated differential distributions of each receptor subtype in distinct neuronal populations with specific neurotransmitter identities in brainstem cholinergic/monoaminergic neurons. In the laterodorsal tegmental and pedunculopontine tegmental nuclei especially, cholinergic neurons exclusively expressed OX1R mRNA, but OX2R mRNA was expressed mainly in GABAergic putative interneurons. Thus, each orexin receptor subtype plays differential roles in gating NREM and REM sleep through distinct neuronal pathways. © 2011 by the authors.発行後1年より全文公開