Sara RydbergResearcher, Departmental study director and Director of Study in Plant Physiology
About me
Principle investigator of the “Source, fate and impacts of the neurotoxin BMAA and DAB” research team.
Phytoplankton are important primary producers in aquatic ecosystems worldwide. However, some species are considered to be harmful, impacting human and animal health through the production of a variety of potent toxins. Two of these toxic metabolites are the beta-N-methylamino-L-alanine (BMAA) and its isomer 2,4-diaminobutyric acid (DAB). BMAA and DAB has shown to be linked to the development of the neurological disorders such as Amyotrophic lateral sclerosis and Alzheimer’s disease. BMAA and DAB are produced by cyanobacteria, diatom and dinoflagellates and bioaccumulates in aquatic food webs with highest levels in bottom-dwelling fish species and filter feeders such as mussels.
As these organisms are used for human consumption and the presence of the toxins BMAA and DAB suggests a route into human body and therefore may act as a major environmental factor eliciting neurodegenerative diseases. In addition, our studies have shown that BMAA is also transferred and accumulated into commercially farmed chickens when they are fed with standard feed mixed with mussels - part of the so called agro-aqua cycle.
Another aspect of these neurotoxic substances, is that our present knowledge on how, why and under what conditions (effect of abiotic and biotic factors) BMAA and DAB are being produced are only speculative. In our team we are using LC-MS/MS and metabolomic analysis in order to better understand the function and biosynthesis of theses metabolites. We are foremost working with diatom models but also with cyanobacteria.
Publications
A selection from Stockholm University publication database
-
Effect and function of β-N-methylamino-L-alanine in the diatom Phaeodactylum tricornutum
2022. Sea-Yong Kim, Ulla Rasmussen, Sara Rydberg. Science of the Total Environment 830
ArticleRead more about Effect and function of β-N-methylamino-L-alanine in the diatom Phaeodactylum tricornutumThe neurotoxin β-N-methylamino-L-alanine (BMAA) is an environmental factor connected to neurodegenerative diseases. BMAA can be produced by various microorganisms (e.g. bacteria, cyanobacteria, dinoflagellates and diatoms) present in diverse ecosystems. No previous study has revealed the function of BMAA in diatoms. In the present study, we combined physiological data with metabolomic and transcriptional data in order to investigate the effect and function of BMAA in the diatom Phaeodactylum tricornutum. P. tricornutum, exposed to different concentrations of exogenous BMAA, showed concentration dependent responses. When the concentration of supplemented BMAA was sufficient to arrest the growth of P. tricornutum, oxidative stress and obstructed carbon fixation were obtained from the specific metabolite and transcriptional data. Results also indicated increased concentration of intracellular chlorophyll a and alterations in the GS-GOGAT cycle, whereas the urea cycle was suppressed. We therefore conclude that BMAA represents a toxic metabolite able to control the growth of P. tricornutum by triggering oxidative stress, and further influencing photosynthesis and nitrogen metabolisms.
-
Evidence of 2,4-diaminobutyric acid (DAB) production as a defense mechanism in diatom Thalassiosira pseudonana
2022. Sea-Yong Kim (et al.). Aquatic Toxicology 249
ArticleRead more about Evidence of 2,4-diaminobutyric acid (DAB) production as a defense mechanism in diatom Thalassiosira pseudonanaThe neurotoxic secondary metabolite β-N-methylamino-L-alanine (BMAA) and its structural isomer 2,4-diaminobutyric acid (DAB) are known to be produced by various phytoplankton groups. Despite the worldwide spread of these toxin producers, no obvious role and function of BMAA and DAB in diatoms have been identified. Here, we investigated the effects of biotic factors, i.e., predators and competitors, as possible causes of BMAA and/or DAB regulation in the two diatom species Phaeodactylum tricornutum and Thalassiosira pseudonana. DAB was specifically regulated in T. pseudonana by the presence of predators and competitors. The effects of DAB on both diatoms as competitors and on the copepod Tigriopus sp. as predator at individual and at population levels were examined. The toxic effects of DAB on the growth of T. pseudonana and the population of Tigriopus sp. were significant. The effect of DAB as a defensive secondary metabolite is assumed to be environmentally relevant depending on the number of the copepods. The results show a potential function of DAB that can play an important role in defense mechanisms of T. pseudonana.
-
No β-N-Methylamino-L-alanine (BMAA) Was Detected in Stranded Cetaceans from Galicia (North-West Spain)
2022. Lucía Soliño (et al.). Journal of Marine Science and Engineering 10 (3)
ArticleRead more about No β-N-Methylamino-L-alanine (BMAA) Was Detected in Stranded Cetaceans from Galicia (North-West Spain)The neurotoxin β-N-methylamino-L-alanine (BMAA), a non-proteinogenic amino acid produced by several species of both prokaryotic (cyanobacteria) and eukaryotic (diatoms) microorganisms, has been proposed to be associated with the development of neurodegenerative diseases. At first, BMAA appeared to be ubiquitously present worldwide in various organisms, from aquatic and terrestrial food webs. However, recent studies, using detection methods based on mass spectrometry, instead of fluorescence detection, suggest that the trophic transfer of BMAA is debatable. This study evaluated BMAA in 22 cetaceans of three different species (Phocoena phocoena, n = 8, Delphinus delphis, n = 8, and Tursiops truncatus, n = 6), found stranded in North-West Spain. BMAA analysis of the liver, kidney, or muscle tissues via sensitive liquid chromatography with tandem mass spectrometry did not reveal the presence of this compound or its isomers. The absence recorded in this study highlights the need to better understand the trophic transfer of BMAA and its anatomical distribution in marine mammals.
-
Transfer of the Neurotoxin beta-N-methylamino-l-alanine (BMAA) in the Agro-Aqua Cycle
2020. Sea-Yong Kim, Sara Rydberg. Marine Drugs 18 (5)
ArticleRead more about Transfer of the Neurotoxin beta-N-methylamino-l-alanine (BMAA) in the Agro-Aqua CycleThe neurotoxic non-protein amino acid beta-N-methylamino-l-alanine (BMAA) is connected to the development of neurodegenerative diseases. BMAA has been shown to accumulate in aquatic ecosystems, and filter-feeding molluscs seem particularly susceptible to BMAA accumulation. The blue mussels farmed along the Swedish coastline in the Baltic Sea are, due to their small size, exclusively used to produce feed for chicken and fish in the agro-aqua cycle. We have investigated the possible biotransfer of BMAA from mussels, via mussel-based feed, into chickens. Chickens were divided into two groups, the control and the treatment. BMAA was extracted from the muscle, liver, brain, and eye tissues in both chicken groups; a UPLC-MS/MS method was subsequently used to quantify BMAA. The results indicate detectable concentrations of BMAA in both chicken groups. However, the BMAA concentration in chicken was 5.65 times higher in the treatment group than the control group, with the highest concentration found in muscle tissue extracted from the treatment group chickens. These data suggest that there is a BMAA transfer route within the agro-aqua cycle, so further investigation is recommended before using mussel-based feed in the chicken industry.
-
Kinetics of beta-N-methylamino-L-alanine (BMAA) and 2, 4-diaminobutyric acid (DAB) production by diatoms: the effect of nitrogen
2019. Sandra Lage (et al.). European journal of phycology 54 (1), 115-125
ArticleRead more about Kinetics of beta-N-methylamino-L-alanine (BMAA) and 2, 4-diaminobutyric acid (DAB) production by diatomsThe neurotoxins beta-N-methylamino-L-alanine (BMAA) and 2,4-diaminobutyric acid (DAB) are produced by cyanobacteria, diatoms and dinoflagellates and have been detected in seafood worldwide. Our present knowledge of their metabolism or biosynthesis is limited. In this study, the production of BMAA and DAB as a function of time was monitored in five strains representing four species of diatoms, i.e. Phaeodactylum tricornutum, Thalassiosira weissflogii, Thalassiosira pseudonana and Navicula pelliculosa, previously identified as BMAA and DAB producers. Subsequently, three strains were selected and exposed to three nitrogen treatments - starvation, control (the standard concentration in f/2 medium) and enrichment, because BMAA metabolism has been suggested to be closely associated with cellular nitrogen metabolism in both cyanobacteria and diatoms. Chlorophyll a and total protein concentrations were also determined. Our results indicate that BMAA and DAB production in diatoms is species- and strain-specific. However, production might also be affected by stress, particularly as related to nitrogen starvation and cell density. Furthermore, this study shows a significant correlation between the production of the two neurotoxins which might further suggest common steps in the metabolic pathways.
Show all publications by Sara Rydberg at Stockholm University