Biology subjects

Souza, L.

Publications and source records attributed to Souza, L..

4 recordsLinked to original sources

bioRxiv2025

Warming disrupts plant-fungal endophyte symbiosis more strongly in leaves than roots

Disruptions to species interactions from global change will negatively impact plant primary production, with broader consequences for species abundances, distribution, and community composition. Fungal endophytes that live inside plant leaves and roots could potentially mitigate plant heat stress from global warming. Conversely, disruptions of these symbioses could exacerbate the negative impacts of warming. To better understand the consistency and strength of warming-induced changes to fungal endophytes, we examined fungal leaf and root endophytes in three grassland warming experiments in the US ranging from 2 to 25 years and spanning 2000 km, 12 {degrees}C of mean annual temperature, and 600 mm of precipitation. We found that experimental warming disrupted symbiosis between plants and fungal endophytes. Colonization of plant tissues by septate fungi decreased in response to warming by 90% in plant leaves and 35% in roots. Warming also reduced fungal diversity and changed community composition in plant leaves but not roots. The strength, but not direction, of warming effects on fungal endophytes varied by up to 75% among warming experiments. Finally, warming decoupled fungal endophytes from host metabolism. Overall, warming-driven disruption of fungal endophyte community structure and function suggests that this symbiosis may not be a reliable mechanism to promote plant resilience and ameliorate stress responses under global change.

ecology↗

bioRxiv2022

(Pro)Renin Receptor Antagonism Attenuates High-Fat-Die-Induced Hepatic Steatosis in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) comprises a spectrum of liver damage directly related to diabetes, obesity, and metabolic syndrome. The (pro)renin receptor (PRR) has recently been demonstrated to play a role in glucose and lipid metabolism. Here, we hypothesized that inhibition of the PRR would prevent the development of diet-induced hepatic steatosis and fibrosis. To test our hypothesis, we fed wild-type mice on a C57Bl/6J background either a high-fat diet (HFD; 60% calories from fat) or normal fat diet (NFD; 10% calories from fat) with matching calories for 6 weeks. An 8-week methionine choline-deficient (MCD) diet was used to induce fibrosis in C57BL/6J mice. Two weeks following diet treatment, mice were implanted with a subcutaneous osmotic pump delivering either PRO20, a peptide PRR antagonist, or scrambled peptide (700 g/kg/d) for 4 or 6 weeks. We found that a 6-week HFD significantly increased liver lipid accumulation, as detected by Oil Red O staining, and liver triglyceride content compared with NFD-fed mice. Importantly, PRO20 treatment significantly reduced hepatic lipid accumulation in HFD-fed mice without affecting body weight or glucose levels. Furthermore, PRR antagonism attenuated HFD-induced steatosis, particularly microvesicular steatosis. In the MCD diet model, the percentage of collagen area detected by Sirius Red staining was reduced in PRO20-treated compared with control mice. PRO20 treatment also significantly decreased levels of liver alanine aminotransferase (ALT), an indicator of liver damage, in MCD-fed mice compared with controls. Mechanistically, we found that PRR antagonism prevented HFD-induced increases in PPAR{gamma} and glycerol-3-phosphate acyltransferase 3 expression in the liver. Taken together, our findings establish the mechanism by which PRR regulates lipid metabolism in the liver and suggest the therapeutic potential of PRR antagonism for the treatment of liver steatosis and fibrosis development in NAFLD.

pathology↗

bioRxiv2019

The cyanobacterial saxitoxin exacerbates neural cell death and brain malformations induced by Zika virus

The northeast (NE) region of Brazil commonly goes through drought periods, which favor cyanobacterial blooms, capable of producing neurotoxins with implications for human and animal health. The most severe dry spell in the history of Brazil occurred between 2012 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus (ZIKV) outbreak was described in the NE region of Brazil during the same years. In this work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance showed higher cyanobacteria amounts and STX occurrence in human drinking water supplies of NE compared to other regions of Brazil. Experimentally, we described that STX doubled the amount of ZIKV-induced neural cell death in progenitor areas of human brain organoids, while the chronic ingestion of water contaminated with STX before and during gestation caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a public health concern regarding the consequences of arbovirus outbreaks happening in areas with droughts and/or frequent freshwater cyanobacterial blooms.\n\nAuthor summaryThe uncontrolled spreading of cyanobacteria in drinking water reservoirs has been the cause of serious public health problems worldwide. Toxin-producing cyanobacterial blooms commonly occur during drought periods in the northeast (NE) region of Brazil. During Zika Virus (ZIKV) outbreak in 2015-16, Brazilian NE showed disproportionately higher microcephaly incidence. Here, we test the hypothesis that the cyanotoxin saxitoxin (STX) may act as a co-insult for ZIKV. Water quality surveillance data showed increased cyanobacteria population and higher STX amount in NE region during 2014-2018. In vitro, we observed that neural progenitor cell death was doubled after STX exposure to ZIKV-infected brain organoids. In vivo, chronic ingestion of STX during gestational period potentiated ZIKV-derived brain abnormalities in newborn mice. Our study provides new insights that may explain the discrepancies among Brazilian regions regarding CZS severity. Moreover, the data highlight the importance of cyanobacteria and cyanotoxin freshwater monitoring for future arbovirus outbreaks.

neuroscience↗

bioRxiv2018

A Public Database on Traumatic Brachial Plexus Injury

We hereby present the first worldwide public digital database centred on adult Traumatic Brachial Plexus Injury (TBPI). This initiative aims at reducing distance between clinical and experimental practice and encouraging data sharing and reuse. Detailed electronic questionnaires made with the free software LimeSurvey were designed to collect patients epidemiological, physical and clinical data. The freely available software Neuroscience Experiments System (NES) was employed to support data storage and management. First results of this effort concern data collected from 109 Brazilian adult TBPI patients with varying degrees of functional impairment. The sample is composed by large majority of men (84.4%), mean age of 32.1 (11.3 SD) years old, victims of motorcycle accidents (67%). The similarity of this dataset basic descriptors with those from previous reports in TBPI validates the strategies employed herein. Managing data from diverse provenance in TBPI may allow identifying functional markers related to the patients clinical improvement and foster the development of new investigative tools to unveil its mechanisms.

neuroscience↗