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1.
Environ Sci Technol ; 58(3): 1473-1483, 2024 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-38205949

RESUMO

Though toxins produced during harmful blooms of cyanobacteria present diverse risks to public health and the environment, surface water quality surveillance of cyanobacterial toxins is inconsistent, spatiotemporally limited, and routinely relies on ELISA kits to estimate total microcystins (MCs) in surface waters. Here, we employed liquid chromatography tandem mass spectrometry to examine common cyanotoxins, including five microcystins, three anatoxins, nodularin, cylindrospermopsin, and saxitoxin in 20 subtropical reservoirs spatially distributed across a pronounced annual rainfall gradient. Probabilistic environmental hazard analyses identified whether water quality values for cyanotoxins were exceeded and if these exceedances varied spatiotemporally. MC-LR was the most common congener detected, but it was not consistently observed with other toxins, including MC-YR, which was detected at the highest concentrations during spring with many observations above the California human recreation guideline (800 ng/L). Cylindrospermopsin was also quantitated in 40% of eutrophic reservoirs; these detections did not exceed a US Environmental Protection Agency swimming/advisory level (15,000 ng/L). Our observations have implications for routine water quality monitoring practices, which traditionally use ELISA kits to estimate MC levels and often limit collection of surface samples during summer months near reservoir impoundments, and further indicate that spatiotemporal surveillance efforts are necessary to understand cyanotoxins risks when harmful cyanobacteria blooms occur throughout the year.


Assuntos
Toxinas Bacterianas , Cianobactérias , Humanos , Microcistinas/análise , Qualidade da Água , Toxinas Marinhas , Toxinas Bacterianas/análise , Água Doce/análise , Água Doce/química , Água Doce/microbiologia , Toxinas de Cianobactérias , Cianobactérias/química , Monitoramento Ambiental/métodos
2.
Harmful Algae ; 130: 102542, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38061823

RESUMO

Cyanobacterial blooms and the toxins they produce pose a growing threat worldwide. Mitigation of such events has primarily focused on phosphorus management and has largely neglected the role of nitrogen. Previous bloom research and proposed management strategies have primarily focused on temperate, dimictic lakes, and less on warm-monomictic systems like those at subtropical latitudes. The in-lake conditions, concentration of total microcystins, and microbial functioning of twenty warm-monomictic lakes in the southcentral United States were explored in the spring and summer of 2021. Our data revealed widespread microcystins in lakes across this region, some of which exceeded regulatory limits. Microcystins were higher in the spring compared to the summer, indicating that warm-monomictic lakes, even across a large range of precipitation, do not follow the trends of temperate dimictic lakes. Microcystins were found in surface waters and bottom waters well below the photic zone, reflecting the persistence of these toxins in the environment. Principal components analyses showed a strong association between microcystins, nitrate + nitrite, and Planktothrix relative abundance and transcriptional activity. Many systems exhibited stronger denitrification in the spring, perhaps contributing to the decreased toxin concentrations in the summer. Counter to most sampled lakes, one lake with the highest concentration of total microcystins indicated nitrogen cycle disruption, including inhibited denitrification. These findings are relevant to mitigating cyanobacterial blooms and toxin production in warm-monomictic systems, and suggests a need to consider nitrogen, and not solely phosphorus, in nutrient management discussions.


Assuntos
Cianobactérias , Microcistinas , Estados Unidos , Microcistinas/análise , Lagos/microbiologia , Nitratos/análise , Nitritos/análise , Ciclo do Nitrogênio , Nitrogênio/análise , Fósforo/análise
3.
Science ; 376(6589): 138-139, 2022 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-35389800

RESUMO

A simple, pervasive biological entity in the ocean sheds light on evolution.


Assuntos
Evolução Biológica , Vírus de RNA , Vírus de RNA/genética
4.
Proc Natl Acad Sci U S A ; 116(31): 15590-15595, 2019 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-31308237

RESUMO

The building blocks of a virus derived from de novo biosynthesis during infection and/or catabolism of preexisting host cell biomass, and the relative contribution of these 2 sources has important consequences for understanding viral biogeochemistry. We determined the uptake of extracellular nitrogen (N) and its biosynthetic incorporation into both virus and host proteins using an isotope-labeling proteomics approach in a model marine cyanobacterium Synechococcus WH8102 infected by a lytic cyanophage S-SM1. By supplying dissolved N as 15N postinfection, we found that proteins in progeny phage particles were composed of up to 41% extracellularly derived N, while proteins of the infected host cell showed almost no isotope incorporation, demonstrating that de novo amino acid synthesis continues during infection and contributes specifically and substantially to phage replication. The source of N for phage protein synthesis shifted over the course of infection from mostly host derived in the early stages to more medium derived later on. We show that the photosystem II reaction center proteins D1 and D2, which are auxiliary metabolic genes (AMGs) in the S-SM1 genome, are made de novo during infection in an apparently light-dependent manner. We also identified a small set of host proteins that continue to be produced during infection; the majority are homologs of AMGs in S-SM1 or other viruses, suggesting selective continuation of host protein production during infection. The continued acquisition of nutrients by the infected cell and their utilization for phage replication are significant for both evolution and biogeochemical impact of viruses.


Assuntos
Organismos Aquáticos , Proteínas de Bactérias , Bacteriófagos , Nitrogênio/metabolismo , Complexo de Proteína do Fotossistema II , Synechococcus , Proteínas Virais , Organismos Aquáticos/genética , Organismos Aquáticos/metabolismo , Organismos Aquáticos/virologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Bacteriófagos/genética , Bacteriófagos/metabolismo , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo , Synechococcus/genética , Synechococcus/metabolismo , Synechococcus/virologia , Proteínas Virais/genética , Proteínas Virais/metabolismo
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