Full text
| |
| Author(s): |
Giulia Magri Ribeiro
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2023-08-22 |
| Examining board members: |
Daniel José Galafasse Lahr;
João Marcelo Pereira Alves;
Elisa Maria Costa e Silva de Paiva;
Roy Timothy Patterson
|
| Advisor: | Daniel José Galafasse Lahr |
| Abstract | |
Microbial eukaryotes, including so-called protists, are crucial in maintaining global ecosystems. The quality of environments is essential in defining the communities of organisms that occupy them. Factors like temperature, salinity, pH, oxygen levels, and the community of organisms present influence the environments quality. Organisms can positively impact the environment through decomposition, nutrient cycling, and habitat creation, while habitat destruction and pollution have adverse effects. Human activities have increased the frequency and intensity of environmental stressors, exacerbating their effects. Testate amoebae, particularly from the Arcellinida group, exhibit varying degrees of stress tolerance and may serve as bioindicators that reflect environmental conditions and the effectiveness of environmental actions. This study investigated the effects of multiple anthropogenic environmental stresses on testate amoebae. We aimed to understand these organisms community and individual responses to two specific stresses: arsenic contamination and eutrophication/low oxygen. We combined community characterization using metabarcoding, functional characterization through gene expression profiling, and mechanistic and evolutionary understanding using bioinformatics. We demonstrated the constitutive expression of resistance metabolisms in Arcella uspiensis and its ability to adjust to stressful conditions. We also demonstrate the multiple acquisition routes of environmental resistance genes through phylogenetic trees. In addition, we discussed the application of metabarcoding strategies to explore ecological adaptation and resilience at the community level. We expanded the COI marker database and conducted a small metabarcoding study, obtaining information on the diversity, biogeography, and potential of Arcellinida as bioindicators. We discovered that the sampled environments physicochemical properties are important determinants of the composition of the Arcellinida community. Also, we started the development of applied techniques such as quantitative real-time PCR (qPCR) of resistance genes using Arcella uspiensis as a model organism. The diversity of strategies among different lineages in adapting to arsenic and low oxygen conditions, with variations in resistance mechanisms, is crucial for understanding specific adaptations and their consequences, particularly for eukaryotic microorganisms. We concluded that Arcella uspiensis has a constitutively expressed basic resistance framework reflecting its ability to adapt to stressful conditions and increase the chances of survival. We also recognize the need to develop the genome and use Arcella uspiensis as a model organism for future research. (AU) | |
| FAPESP's process: | 19/22109-0 - Evaluation of the impact of environmental conditions on the taxonomic and functional diversity of testate amoebae |
| Grantee: | Giulia Magri Ribeiro |
| Support Opportunities: | Scholarships in Brazil - Doctorate |