Publications by authors named "Helena H Vieira"
Article Synopsis
- Telonemia are ancient marine protists with established evolutionary links to the SAR supergroup, but their ecological roles and distribution in freshwater environments remain under-researched.
- A global study of over a thousand freshwater metagenomes and 407 samples from lakes revealed a wide distribution of Telonemia, though no new major clades were identified, indicating their diversity is well-represented in current surveys.
- Findings suggest Telonemia prefer colder, deeper areas of lakes in the Northern Hemisphere, where they can make up 10%-20% of the heterotrophic flagellate population, highlighting their significance in freshwater food webs.
Article Synopsis
- Photosynthetic cryptophytes are important protists in freshwater ecosystems, especially contributing to spring phytoplankton blooms.
- Bloom collapse is mainly influenced by environmental changes and grazing, but the impact of viruses on this process in freshwater has been less understood.
- This study identified and characterized a virus that affects cryptophyte populations, representing a significant group of giant viruses found globally in freshwater environments.
Reports of programmed cell death (PCD) in phytoplankton raise questions about the ecological evolutionary role of cell death in these organisms. We induced PCD by nitrogen deprivation and unregulated cell death (non-PCD) in one strain of the green microalga and investigated the effects of the cell death supernatants on phylogenetically related co-occurring organisms using growth rates and maximum biomass as proxies of fitness. PCD-released materials from CCMA-UFSCar-3 significantly increased growth rates of two conspecific strains compared to healthy culture (HC) supernatants and improved the maximum biomass of all strains compared to related species.
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- Local and regional factors influence the turnover of microbial communities, with local selection affecting assembly through interactions and regional factors impacting dispersion patterns.
- The study examined three microbial subcommunities in tropical freshwater reservoirs during dry and rainy seasons to understand how these conditions affect community composition.
- Findings revealed that selection played a significant role for free-living communities under dry conditions due to environmental heterogeneity, while cyanobacterial communities were more influenced by stochastic drift; each subcommunity exhibited unique turnover patterns based on diversity, lifestyle, and spatial dynamics.