The crater lake of El Chichón active volcano represents one of the most important extreme ecosystems in the world due to its high temperatures, low pH and the appearance of high concentrations of heavy metals because of volcanic activity. The latter is of great importance in nearby volcano sites due to heavy metal pollution, which is one of the worst types of environmental problems in the world. In this study, the concentration of heavy metals was evaluated in soils and sediments from different sections in the crater lake of El Chichón volcano. Representative samples were collected from four sediments and soils in 2015 and 2017. These samples were analyzed for 20 metals by inductively coupled plasma-optical emission spectrometry (ICP-OES). The most abundant elements in sediments of the crater lake of “El Chichón” volcano were Fe, Na, Si, Ca, K and Al and not found in soil samples. Be and Tl were more abundant in the soil, but the concentration of Se was higher in soil without showing statistically significant differences. Principal component analysis (PCA) showed that the abundance of metals was influenced by sample type. That is, a higher concentration of heavy metals and trace elements was found in volcanic sediments as compared to soil samples. This difference may be related to metals originating from the magma, which is partially transported in the water stream that gives way to the volcano lake. The most toxic heavy metals identified and quantified in high concentrations in crater soils and sediments were As and Cd. This study suggests that sediments and soils of El Chichón crater lake could be an important source of heavy metals and toxic elements such as As and Cd.

Metabolic alterations are recognized as one of the hallmarks of cancer. Among these, alterations in mitochondrial function have been associated with an enhanced production of Reactive Oxygen Species (ROS), which activate ROS-regulated cancer cell signaling pathways. Breast cancer is the main cancer-related cause of death for women globally. It is a heterogeneous disease with subtypes characterized by specific molecular features and patient outcomes. With the purpose of identifying differences in energy metabolism and the oxidative stress management system in non-tumorigenic, estrogen receptor positive (ER+) and triple negative (TN) breast cancer cells, we evaluated ROS production, protein enzyme levels and activities and profiled energy metabolism. We found differences in energetic metabolism and ROS management systems between non-tumorigenic and cancer cells and between ER+ and TN breast cancer cells. Our results indicate a dependence on glycolysis despite different glycolytic ATP levels in all cancer cell lines tested. In addition, our data show that high levels of ROS in TN cells are a result of limited antioxidant capacity in the NADPH producing and GSH systems, mitochondrial dysfunction and non-mitochondrial ROS production, making them more sensitive to GSH synthesis inhibitors. Our data suggest that metabolic and antioxidant profiling of breast cancer will provide important targets for metabolic inhibitors or antioxidant treatments for breast cancer therapy.

Natural freshwater streams harbor diverse microbial communities that support ecosystem functioning. Due to their great biodiversity and geomorphological characteristics, these ecosystems are often very attractive ecotourism destinations, which makes them highly vulnerable to anthropogenic disturbances. The Agua Azul Waterfalls (Cascadas de Agua Azul, in Spanish), a major ecotourist destination located in Indigenous territories of southeastern Mexico (Chiapas, Mexico), offer a unique setting to investigate how sustained human activity influences microbial diversity and quality of water and sediments, as well as the role of local management in conserving biodiversity. To determine the ecological sensitivity of this freshwater stream to tourism pressure, we sampled sites spanning gradients of ecotourist activity and performed an integrated analysis of the physicochemical properties, elemental composition and microbial community composition (bacteria, archaea and fungi) of water and sediment samples. Areas associated with ecotourism activities showed notable changes in physicochemical parameters and microbial community composition, indicating localized human-induced impacts on this ecosystem. Although no significant differences were observed between zones, the detection of anaerobic methanogenic archaea and ammonia-oxidizing archaea in shallow sediments suggests that oxygen availability, methanogenesis (both acetoclastic and hydrogenotrophic), and nitrogen metabolism may play important roles in shaping the functioning of this ecosystem. Our findings highlight the potential of microbial diversity in combination with physicochemical parameters as a tool to detect early stages of human impacts on freshwater ecosystems and establish a basis for future monitoring and conservation efforts. Importance: This study provides evidence of the early-stage impacts of ecotourism on biodiversity and water quality at the Agua Azul Waterfalls, a freshwater stream located within a protected natural area in southeastern Mexico. While the water still meets basic quality standards, areas with higher tourist activity show early signs of nutrient enrichment and measurable changes in the types of microbes present and the roles they play in this ecosystem. As the first analysis of microbial diversity in this ecosystem, our work highlights the value of microbes as early and sensitive indicators of human impact. By directly comparing tourist and non-tourist areas, we provide evidence of how recreational pressure is transforming this freshwater environment. We expect that our findings will serve as a guide for local communities and policymakers in developing more sustainable tourism practices, with the goal of preserving the biodiversity, as well as the cultural and economic value, of this ecosystem, before irreversible damage occurs.