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Occurrence of ultraviolet radiation-absorbing mycosporine-like amino acids in coral mucus and whole corals of French Polynesia
Abstract
Specimens of six scleractinian species were gathered during the austral spring
(October–November) 1994 on the external slope of the barrier reef of
Arue, Tahiti, and in the lagoon of Arutua, a Tuamotu island. Mucus of each
specimen was collected and the optical density and volume excreted were
measured. After treatment, mucus was analysed for mycosporine-like amino acids
(MAAs) by high-performance liquid chromatography (HPLC). Nine UV-absorbing
compounds were present in coral mucus at concentrations between 1 and 500 ng
g-1 mucus. Palythine and mycosporine–gly were
found in all mucus studied. Mycosporine–2glycine was recovered in
71% of specimens and shinorine in 28%. Porphyra-334 and
palythinol were identified as minor MAAs. Three recently identified MAAs,
palythine–serine, mycosporine–methylamine:serine and
mycosporine–methylamine:threonine, were also found in mucus from
Pocillopora. Within a genus, there was a qualitative
similarity in MAAs determined by HPLC, irrespective of locality. Values for
optical density of the mucus showed the ability of MAAs to protect the animal
host and endosymbiotic algae from UV-solar flux and, as inferred from the
recent literature, from oxidative forms of oxygen (HO2 .
, O 2- ,
HO.) derived from photosynthesis.
... This mechanism is critical for the survival of corals, as exposure to high levels of UV radiation can cause damage to coral DNA, resulting in a range of negative impacts on coral health and the overall health of the surrounding ecosystem. By providing this important protection against UV radiation, MAAs play a key role in maintaining the health and resilience of coral populations (Teai et al. 1998;Kageyama and Waditee-Sirisattha 2019). Mycosporine-glycine, mycosporine-2glycine, palythine, mycosporine-methylamine-serine, and mycosporine-methylamine-threonine, which were characterized from Lobophyllia, Acropora, Fungia, and Pocillopora species, have all been reported from coral mucus (Teai et al. 1998). ...
... By providing this important protection against UV radiation, MAAs play a key role in maintaining the health and resilience of coral populations (Teai et al. 1998;Kageyama and Waditee-Sirisattha 2019). Mycosporine-glycine, mycosporine-2glycine, palythine, mycosporine-methylamine-serine, and mycosporine-methylamine-threonine, which were characterized from Lobophyllia, Acropora, Fungia, and Pocillopora species, have all been reported from coral mucus (Teai et al. 1998). In addition to their ability to combat oxidative stress, MAAs can protect many marine organisms from the harmful effects of light (Shick and Dunlap 2002). ...
... In addition to their ability to combat oxidative stress, MAAs can protect many marine organisms from the harmful effects of light (Shick and Dunlap 2002). Similarly, mycosporine-glycine showed an additional antioxidant property in coral mucus along with sunscreen, probably protecting endosymbionts from oxidative damage produced through photosynthesis (Teai et al. 1998). Biologically harmful UV rays between 310 and 360 nm are absorbed by MAAs. ...
Coral mucus secreted by mucocytes provides a protective physicochemical and physiological barrier between coral tissue and external environmental threats. The biomolecules and nutrients of the secreted mucus are derived from endosymbionts, coral polyps and support coral functions, such as feeding, sediment clearing and protection, against numerous biotic and abiotic stressors. The surface mucus layer also houses a diverse community of beneficial microorganisms that defend against pathogens. Enzymes including peptidases, esterases, and glycosidases were observed and described in mucus. Most importantly, the presence of phenoloxidase, an intracellular enzyme in secretory mucus, generally triggers melanin synthesis, providing fast-acting components of invertebrate immunity in disease resistance. However, the purpose and the mechanism of mucus release, effects of mucus components on defense properties, and functional roles in intra- and interspecific interactions are not well described. Thus, the present review aims to understand the mucus components and the complex roles played by mucus in microbial associations, feeding, and resilience that influence coral health.
... The bioactive compounds in coral mucus have been experimentally proven to have antimicrobial activity in the defense against infectious disease by inhibiting Bacillus subtilis, Staphylococcus aureus, Salmonella typhimurium, Vibrio species and Serratia marcescens (Brown and Bythell, 2005, Ritchie, 2006, Bakshani et al., 2018. Besides, Mycosporine-like amino acids (MAA), which act as a sunscreen that absorbs UV radiation (Teai et al., 1998), and phenoloxidase (PO) and melanin activity in mucus of healthy and diseased Pseudodiploria strigosa (Rivera-Ortega and Thome, 2018) have also been described. Prophenoloxidase (ProPO) is a major enzyme of coral innate immunity (Cerenius et al., 2008) which gets upregulated due to oxidative stress. ...
The surface mucus layer of corals aids in feeding, silt removal, and defense against pathogens. However, first line
of defense of secreted mucus of corals against tissue damage generated through pathogen or environmental
factors is poorly understood. Hence, we used various methods such as a well diffusion assay and tests for quorum
quenching, free radical scavenging, antioxidant enzyme expression and phenoloxidase (PO) activity to determine
the mucus defense properties using mucus of healthy and diseased Porites sp. and Acropora sp. Interestingly the
coral mucus showed antimicrobial activity against coral pathogens such as bacteria and protozoan ciliates. Inhibition
of the N-Acyl homoserine lactone (AHL) molecule suggests quorum quenching. Free radical scavenging
of mucus was screened using hydrogen peroxide, hydroxyl radical, and 2, 2-diphenyl-1-picrylhydrazyl (DPPH)
methods, which was found significantly more in diseased corals (p < 0.05). Antioxidant enzymes superoxide
dismutase (SOD), catalase, and peroxidase activity were observed in both the diseased and healthy coral mucus.
The presence of serine and metalloproteases was also detected in coral mucus. Further, phenoloxidase (PO)
activity was highest in diseased coral mucus affected by pink line syndrome and white patch Acropora sp. disease
than the healthy coral mucus. Thus, the present study of antimicrobial properties, antioxidant enzymes, and
quorum quenching properties in coral mucus may aid in understanding the corals defense and survival against
pathogens and any abiotic stress.
... Abundance is denoted by intensity of color, ranging from no abundance = white to high abundance = dark green Coral Reefs the microbial structure of our SW samples was influenced by the corals. Mucus shedding is a natural phenomenon in corals (Brown and Bythell 2005) and can be deployed during stressed conditions like increased UV exposure (Teai et al. 1998) and pathogen regulation (Ritchie 2006) but has also been linked to holobiont health via regulation of microbial communities (Glasl et al. 2016). It is possible that exuded dissolved organic matter from the mucus was present in the seawater (Silveira et al. 2017;Weber et al. 2019) and influenced the microbial structure of our SW samples since seawater was collected [ 1 m of the focal corals. ...
Microbiome studies across taxa have established the influence of host genotype on microbial recruitment and maintenance. However, research exploring host-specific epibionts in scleractinian corals is scant, and the influence of intraspecific differences across environments remains unclear. Here, we studied ten Acropora cervicornis genotypes to investigate the relative roles of host genotype and environment in structuring the epibiome. Coral mucus was sampled in a common garden nursery from replicate ramets of distinct genotypes (T0). Coral fragment replicates (n = 3) of each genotype were then transplanted to nine different field sites in the Lower Florida Keys, and mucus was again sampled one year later from surviving ramets (T12). 16S rRNA amplicon sequencing was used to assess microbial composition, richness, and beta-diversity. The most abundant and consistent amplicon sequencing variants (ASVs) in all samples belonged to Midichloriaceae (MD3-55 genus) and Cyanobacteria (Synechococccus). The relative abundances of these bacterial taxa varied consistently between genotypes, whereas neither the composition nor taxonomic relative abundance were significantly different among field sites. Interestingly, several high MD3-55 hosting genotypes showed rapid diversification and an increase in MD3-55 following transplantation. Overall, our results indicate healthy A. cervicornis genotypes retain distinct epibiome signatures through time, suggesting a strong host component. Lastly, our results show that differences in MD3-55 abundances can be consistently detected in the epibiome of distinct host genotypes of A. cervicornis. As this organism (sensu Aquarickettsia rohweri) has been implicated as a marker of disease resistance, this finding reinforces the potential use of microbial indicators in reef restoration efforts via non-invasive surface/mucus sampling.
... The concentration of MAA in marine organisms is linked with the duration and exposure level of UV radiation (Shick et al. 1995(Shick et al. , 1999Ferrier-Pagès et al. 2007) such as the depth Gleason and Wellington 1995;Shick et al. 1995;Corredor et al. 2000), water motion and photosynthetically active radiation (PAR) (Jokiel et al. 1997). Furthermore, the concentration of MAAs secreted by corals varies with coral species and parts (Teai et al. 1998). Even though many compounds from this class follow Lipinski rule of fives such as mycosporine-Gly, mycosporine-2Gly, palythine (Serine/Thr sulfate/Ser-sulfate), palythinol, and asterina-330, the current results have not used cell cultures nor animal models (with the exception of one study). ...
Unlabelled:
Natural extracts and compounds from marine resources have gained intensive scientific and industry attention for radioprotective activities in the past ten years. However, the marine-derived radioprotectants have been studied against UV-rays, gamma (γ)-rays and X-rays for more than 30 years. This review aims to identify key marine-derived extracts/compounds and their modes of action studied for radioprotective activities from 1986 to 2019. A comprehensive survey was conducted to establish the trend in terms of the publications each year and the countries of origin. A total of 40 extracts and 34 natural compounds showing radioprotective activities against UV-rays, gamma (γ)-rays and X-rays were identified from a range of marine plants and animals. These extracts and compounds are broadly categorized into polysaccharides, phlorotannins, carotenoids and mycosporine-like amino acids (MAAs). Macroalgae and microalgae were found to be the dominant sources of polysaccharides, phlorotannins and carotenoids. MAAs were mainly identified in algae, sponges, sea cucumber and corals that showed significant UV-absorbing activities. A number of radioprotective mechanisms were shown by these compounds, predominantly free radicals scavenging, inhibition of apoptosis, UV-ray absorption and DNA damage-repair signaling pathways. While these bio-discoveries warrant further investigation and development of radioprotective therapeutics, however, the lack of clinical studies is a major obstacle to be tackled in the future.
Supplementary information:
The online version contains supplementary material available at 10.1007/s42995-021-00095-x.
Pigments act as tracers to elucidate the fate of phytoplankton in the world's oceans and are often associated with important biogeochemical cycles related to carbon dynamics in the oceans. They are increasingly used in in situ and remote-sensing applications, detecting algal biomass and major taxa through changes in water colour. This book is a follow-up to the 1997 volume Phytoplankton Pigments in Oceanography (UNESCO Press). Since then, there have been many advances concerning phytoplankton pigments. This book includes recent discoveries on several new algal classes particularly for the picoplankton, and on new pigments. It also includes many advances in methodologies, including liquid chromatography-mass spectrometry (LC-MS) and developments and updates on the mathematical methods used to exploit pigment information and extract the composition of phytoplankton communities. The book is invaluable primarily as a reference for students, researchers and professionals in aquatic science, biogeochemistry and remote sensing.
Pigments act as tracers to elucidate the fate of phytoplankton in the world's oceans and are often associated with important biogeochemical cycles related to carbon dynamics in the oceans. They are increasingly used in in situ and remote-sensing applications, detecting algal biomass and major taxa through changes in water colour. This book is a follow-up to the 1997 volume Phytoplankton Pigments in Oceanography (UNESCO Press). Since then, there have been many advances concerning phytoplankton pigments. This book includes recent discoveries on several new algal classes particularly for the picoplankton, and on new pigments. It also includes many advances in methodologies, including liquid chromatography-mass spectrometry (LC-MS) and developments and updates on the mathematical methods used to exploit pigment information and extract the composition of phytoplankton communities. The book is invaluable primarily as a reference for students, researchers and professionals in aquatic science, biogeochemistry and remote sensing.
Alongside the innumerable benefits of solar rays, the adverse effects of ultraviolet (UV) radiation must be considered. All organisms are subjected to the deleterious effects of UV radiation, particularly UVA...
Microbiome studies across taxa have established the influence of host genotype on microbial recruitment and maintenance. However, research exploring host-specific epibionts in scleractinian corals is scant and the influence of intraspecific differences across environments remains unclear. Here, we studied the epibiome of ten Acropora cervicornis genotypes to investigate the relative roles of host genotype and environment in structuring the epibiome. Coral mucus was sampled in a common garden nursery from replicate ramets of distinct genotypes (T0). Coral fragment replicates (n=3) of each genotype were then transplanted to nine different field sites in the Lower Florida Keys and mucus was again sampled one year later from surviving ramets (T12). 16S rRNA amplicon sequencing was used to assess microbial composition, richness, and beta-diversity. The most abundant and consistent amplicon sequencing variants (ASVs) in all samples belonged to Fokiniaceae (MD3-55 genus) and Cyanobacteria (Synechococccus). The abundances of these bacterial taxa varied consistently between genotypes whereas neither the composition nor taxonomic abundance were significantly different among field sites. Interestingly, several high MD3-55 hosting genotypes showed rapid diversification and an increase in MD3-55 following transplantation. Overall, our results indicate healthy A. cervicornis genotypes retain distinct epibiome signatures through time, suggesting a strong host component. Lastly, our results show that differences in MD3-55 abundances can be consistently detected in the epibiome of distinct host-genotypes of A. cervicornis. As this organism (sensu Aquarickettsia rohweri) has been implicated as a marker of disease resistance, this finding reinforces the potential use of microbial indicators in reef restoration efforts via non-invasive surface/mucus sampling.
Global carbon emissions and associated increase in ocean temperatures are understood to be the main driving force in the degradation of coral reefs. Elevated temperatures impact various life stages of scleractinian corals, from the free-floating planulae of brooding corals to older, sexually viable individuals. With global warming, questions have arisen over whether organismal adaptation will be enough to keep up with the pace of environmental change. Researchers have pursued investigations of whether or not rapid acclimatization, through transgenerational plasticity, can help protect populations until genetic adaptation occurs. Acclimatization in corals has been widely studied in all life stages of corals, with the important exception of recently settled juveniles. In this study, I built upon past research by exposing adult Pocillopora damicornis colonies to elevated (28.5°C) or ambient (25.5°C) temperatures and examining the settlement ability and growth of their planulae ex situ . Juveniles from preconditioned parents fared better in higher temperatures compared to their naïve counterparts. Lunar timing of planula release between treatments peaked at different times in the lunar cycle. Peak planula release occurred on lunar day 23 for prestressed corals and on lunar day 7 for corals from ambient temperature seawaters. While future projects should follow up on these preliminary trials with in situ experiments to assess this phenomenon in the field, this study represents an important step in understanding how corals may be able to acclimatize and eventually adapt to climate change.
A novel 330 nm UV absorbing compound, a methylamine substituted mycosporine (1), was isolated from methanol extracts of two hermatypic scleractinians. Structural elucidation yielded the molecular formula C13H22N2O6. This was given the trivial name Mycosporine-methylamine:threonine.