Search

Plastic debris is thought to be widespread in freshwater ecosystems globally 1 . However, a lack of comprehensive and comparable data makes rigorous assessment of its distribution challenging 2,3 . Here we present a standardized cross-national survey that assesses the abundance and type of plastic debris (>250 μm) in freshwater ecosystems. We sample surface waters of 38 lakes and reservoirs, distributed across gradients of geographical position and limnological attributes, with the aim to identify factors associated with an increased observation of plastics. We find plastic debris in all studied lakes and reservoirs, suggesting that these ecosystems play a key role in the plastic-pollution cycle. Our results indicate that two types of lakes are particularly vulnerable to plastic contamination: lakes and reservoirs in densely populated and urbanized areas and large lakes and reservoirs with elevated deposition areas, long water-retention times and high levels of anthropogenic influence. Plastic concentrations vary widely among lakes; in the most polluted, concentrations reach or even exceed those reported in the subtropical oceanic gyres, marine areas collecting large amounts of debris 4 . Our findings highlight the importance of including lakes and reservoirs when addressing plastic pollution, in the context of pollution management and for the continued provision of lake ecosystem services., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Achromatium is large, hyperpolyploid and the only known heterozygous bacterium. Single cells contain approximately 300 different chromosomes with allelic diversity far exceeding that typically harbored by single bacteria genera. Surveying all publicly available sediment sequence archives, we show that Achromatium is common worldwide, spanning temperature, salinity, pH, and depth ranges normally resulting in bacterial speciation. Although saline and freshwater Achromatium spp. appear phylogenetically separated, the genus Achromatium contains a globally identical, complete functional inventory regardless of habitat. Achromatium spp. cells from differing ecosystems (e.g., from freshwater to saline) are, unexpectedly, equally functionally equipped but differ in gene expression patterns by transcribing only relevant genes. We suggest that environmental adaptation occurs by increasing the copy number of relevant genes across the cell's hundreds of chromosomes, without losing irrelevant ones, thus maintaining the ability to survive in any ecosystem type. The functional versatility of Achromatium and its genomic features reveal alternative genetic and evolutionary mechanisms, expanding our understanding of the role and evolution of polyploidy in bacteria while challenging the bacterial species concept and drivers of bacterial speciation., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

From exploring knowledge from wise members of the community to investigating the science of homeostasis, students learn healthy ways of living through a new hands-on curriculum, Diabetes Education in Tribal Schools: Health Is Life in Balance. The curriculum integrates science and Native American traditions to educate students about science, diabetes and its risk factors, and the importance of nutrition and physical activity in maintaining health and balance in life. Applying an inquiry-based approach to learning, the curriculum builds skills in observation, measurement, prediction, experimentation, and communication, and provides healthy lifestyle messages and innovative science activities for all students. The curriculum is now available to teachers and health educators at no cost through a federal grant.Health Is life in Balance incorporates interdisciplinary standards as well as storytelling to help children understand important messages. Implementation evaluation of the curriculum indicated improved knowledge and attitudes about science and health, positive teacher and student comments, and culturally relevant content. The lessons highlighted in this article give a glimpse into this hands-on curriculum which integrates science and Native American traditions, looking to our past and listening to the wisdom of our Elders, to gain powerful information for healthy, holistic living. The circle of balance is a theme in many indigenous belief systems and is woven into the lessons, providing enduring understandings of health behaviours that can prevent type 2 diabetes in the context of Native American cultural themes.