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- Assessing traffic-derived soil contamination: Insights from earthworm bioaccumulation and histomorphological responsesPublication . Coelho, Nádia; Camarinho, Ricardo; Garcia, Patrícia; dos Santos Rodrigues, ArmindoABSTRACT: This study aims to evaluate traffic-derived soil contamination using Amynthas gracilis (Kinberg, 1867) earthworms as bioindicators, with insights from bioaccumulation and histomorphological responses. Road pollution arises from multiple sources, including vehicle emissions, tire and brake wear, and stormwater runoff, with extensive environmental impacts. The negative impacts of heavy traffic pollution are well-recognized, but less information is available on that of moderate traffic road pollution. Besides serving as proxies for soil contamination, earthworms provide information on contaminant bioavailability and biological responses. Soil and A. gracilis earthworm samples were collected on either side of three roads in São Miguel Island, Azores, Portugal, with varying average annual daily traffic: Lagoa–Ponta Delgada (44.300 annual daily traffic), Lagoa–Ribeira Grande (9092 annual daily traffic), and Coroa da Mata–Santa Iria (<400 annual daily traffic), labelled MHT, MT, and LT sites. Soil and earthworm elemental concentrations were measured; soil elemental contamination and earthworm bioaccumulation factors were calculated. Earthworm histomorphometrical and histomorphological data were gathered to assess the impact of chronic exposure to moderate traffic road pollution on bioindicator tissues. Enrichment factors were elevated for Bi in MHT and MT sites, and Co in MT site; earthworms bioaccumulated As, Cd, Hg, Sb, Zn. Histological analyses revealed alterations in earthworm tissues indicative of physiological stress, namely thicker integument and peritrophic matrix (both of which reflect enhanced barrier function), thinner intestinal epithelium (reflecting impaired nutrient absorption and higher cellular turnover), and a higher proportion of mucous cells (reflecting enhanced barrier function) in the integument of earthworms from MHT and MT sites. The impact of moderate levels of traffic pollution is demonstrated by its contribution to soil contamination. The potential of using A. gracilis earthworms as sensitive bioindicators to moderate levels of road pollution is highlighted.
- Novelty, diversity, and genetic dark matter in enterococci of invertebratesPublication . Sgardioli, Bruna; Phillips, Matthew; Miklos, Arjun; Fleiszig-Evans, Kailey; Manson, Abigail; Mello, Suelen; Shea, Terrance; Urhan, Aysun; Whipple, Ryan; Salamzade, Rauf; Sanders, Jasper; Borges, P.A.V.; Dapkevicius, Maria de Lurdes; Earl, Ashlee; Gilmore, MichaelABSTRACT: Enterococci appear to have originated in the guts of early terrestrializing arthropods and invertebrates over 425 million years ago—hosts that are now highly diverse and widespread in nature today. Yet most knowledge of the genus comes from human infection-associated lineages with genomes swollen by the recent accretion of foreign DNA conveyed by mobile elements. Because invertebrates dominate terrestrial animal diversity and biomass, they would be predicted to constitute a major but little-explored reservoir of enterococcal diversity. We therefore systematically examined Enterococcus association and species diversification in invertebrate hosts of the comparatively natural, isolated, but well-characterized environment of the Azorean island of Terceira. Over 100 invertebrate specimens were examined for associated enterococci, which were taxonomically classified by whole-genome sequencing. Supporting the existence of a large pool of uncharacterized enterococci and Enterococcus-adapted genes, 40% (eight of 20) of the Enterococcus species identified were either undescribed, including four candidate new species described here, or very recently discovered. In contrast, control isolates from vertebrates were exclusively of known species typical of sampling elsewhere, discounting geographic isolation as a main driver of the novelty observed. Further, because of the abundance of E. casseliflavus and E. flavescens in this collection, we obtained the resolution necessary to quantify the divergence and decipher the drivers of speciation in the controversial division between these naturally vancomycin-resistant species. These findings provide robust support for the existence of a large pool of new species and unexplored adaptive traits in invertebrate-associated enterococci—diverse environmental survival traits optimized for expression in an enterococcal background, and well positioned for transmission into human-associated enterococcal strains.