Microbial community structure and co-occurrence network stability in seawater and microplastic biofilms under prometryn pollution in marine ecosystems.

Prometryn has been extensively detected in marine environment because of its widespread usage in agriculture and aquaculture and has been concerns since its serious effects on aquatic organisms. However, its impact on the microbial community in the marine ecosystem including seawater and biofilm is still unclear. Therefore, a short-term indoor microcosm experiment of prometryn exposure was conducted. This study found that prometryn had a more significant impact on the structure and stability of the microbial community in seawater compared to microplastic biofilms. Additionally, we observed that the assembly of the microbial community in biofilms was more affected by stochastic processes than in seawater under the exposure of prometryn. Our study provided evidence for the increasing impact of the microbial communities under the stress of prometryn and microplastics.

The co-presence of polystyrene nanoplastics and ofloxacin demonstrates combined effects on the structure, assembly, and metabolic activities of marine microbial community.

Nanoplastic is increasing in environments and can address toxic effects on various organisms. Particle size, concentration, and surface functionalization most influence nanoplastic toxicity. Besides, nanoplastic can adsorb other contaminants (e.g., antibiotics) to aggravate its adverse effects. The combined effects of nanoplastics and antibiotics on planktonic/benthic microbial communities, however, are still largely unknown. In this study, the combined effects of polystyrene nanoplastic and ofloxacin on the structure, assembly, and metabolic activities of marine microbial communities were investigated based on amplicon sequencing data. The results mainly demonstrate that: (1) nanoplastic and ofloxacin have greater impacts on prokaryotic communities than eukaryotic ones; (2) niche breadths of planktonic prokaryotes and benthic eukaryotes were shrank with both high nanoplastic and ofloxacin concentrations; (3) increased ofloxacin mainly reduces nodes/edges of co-occurrence networks, while nanoplastic centralizes network modularity; (4) increased nanoplastic under high ofloxacin concentration induces more differential prokaryotic pathways in planktonic communities, while benthic communities are less influenced. The present work indicates that co-presence of nanoplastics and ofloxacin has synergistic combined effects on community structure shifts, niche breadth shrinking, network simplifying, and differential prokaryotic pathways inducing in marine microbial communities, suggesting nanoplastics and its combined impacts with other pollutions should be paid with more concerns.

Characteristics of microplastic pollution in golden pompano (Trachinotus ovatus) aquaculture areas and the relationship between colonized-microbiota on microplastics and intestinal microflora.

Microplastic (MPs) pollution is a global marine environmental problem. The effects of MPs on the gut microbiota of aquatic organisms have received considerable attention. For example, microbes colonizing MPs in pond cultures alter the structure and function of the intestinal microbes of shrimp and fish. It was hypothesized that bacteria on MPs in natural mariculture areas also interact with the intestinal flora of golden pompano (Trachinotus ovatus) because biofilms can form on the surface of MPs during long-term floating in seawater. To our knowledge, this study is the first to investigate MPs pollution in T. ovatus aquaculture. DNA sequencing and bioinformatics analysis confirmed the effect of microbial colonization of MPs on the intestinal flora of T. ovatus. The MPs detected in the gut wet weight (w.w.) of golden pompano (546 ± 52 items/g) were mainly pellets and fragments of blue or green, whereas the sediment MPs dry weight (d.w.) (4765 ± 116 items/kg) were mainly black fibers. The MPs richness in the sediment gradually increased from the open-sea aquaculture area to the estuarine aquaculture area and was positively correlated with the MPs richness in the intestinal tract of golden pompano. MPs 20-200 µm were the most common in the gut and sediment. The intake of MPs increased the abundance of Proteobacteria and decreased that of Firmicutes in the intestinal flora. The functional compositions of MP-colonizing microbes and gut microbiota were similar, suggesting that the two communities influence each other. Network analysis further confirmed this and revealed that Vibrio plays a key role in the intestinal flora and surface microorganisms of MPs. Overall, the intake of MPs by aquatic animals not only affects the intestinal flora and intestinal microbial function, but also poses potential risks to aquaculture.

The combined effects of microplastics and the heavy metal cadmium on the marine periphytic ciliate Euplotes vannus.

Microplastics could be grazed by marine organisms and possibly transferred to higher trophic levels along the microbial loop. Due to their size and capacity to concentrate heavy metals that trigger joint toxic effects, microplastics (MPs) have already become a severe threat to marine organisms. The detrimental effects of MPs on large marine organisms have been studied, but the combined toxicity of MPs and cadmium (Cd) on protozoan ciliates remains unclear. In the present study, we selected different diameters and concentrations of polystyrene microspheres (PS-MPs) and Cd2+ as model MPs and heavy metals to evaluate their single and combined effects on the periphytic marine ciliate Euplotes vannus in relation to carbon biomass and oxidative stress. The MPs were indeed ingested by Euplotes vannus and significantly reduced the abundance and carbon biomass of ciliate populations. Combined exposure to MPs and Cd2+ not only increased the bioaccumulation of Cd2+ in ciliates but also exacerbated the decrease in ciliate biomass by increasing oxidative stress and membrane damage. In comparison, the effects of nano-sized plastics (0.22 µm) were more harmful than those of micro-sized plastics (1.07 µm, 2.14 µm and 5.00 µm). A smaller size represents a higher potential for penetrating biological members and a stronger adsorption capacity for cadmium. These results provide new insight into the combined toxicity of microplastics and heavy metals on ciliated protozoa and lay a foundation for higher trophic levels and ecosystems.

Redescription and molecular characterization of two Trichodina species (Ciliophora, Peritrichia, Mobilida) from freshwater fish in China.

During an investigation of parasitic ciliates in northern China, two Trichodina species, T. acuta Lom, 1970 and T. nigra Lom, 1960, were isolated from the freshwater fish Cyprinus carpio Linnaeus, 1758. The morphology of each species was investigated based on dry silver nitrate-stained specimens. In addition, the molecular phylogeny of each was analyzed based on small subunit ribosomal DNA (SSU rDNA) sequence data. Trichodina acuta can be distinguished from its congeners by the undefined periphery of the central circle, the distinct gap between the rays and the central circle, and the distinctly sickle-shaped blades. Trichodina nigra is a cosmopolitan ciliate and is characterized by its densely linked denticles, broad, rounded spatula-shaped blades, robust central parts, and well developed rays. Phylogenetic analyses revealed that T. acuta and T. nigra nest within different clades, supporting the assertion that the GC content of SSU rDNA sequences could reflect evolutionary relationships among Trichodina species.

Self-healing polyurethane-elastomer with mechanical tunability for multiple biomedical applications in vivo.

The unique properties of self-healing materials hold great potential in the field of biomedical engineering. Although previous studies have focused on the design and synthesis of self-healing materials, their application in in vivo settings remains limited. Here, we design a series of biodegradable and biocompatible self-healing elastomers (SHEs) with tunable mechanical properties, and apply them to various disease models in vivo, in order to test their reparative potential in multiple tissues and at physiological conditions. We validate the effectiveness of SHEs as promising therapies for aortic aneurysm, nerve coaptation and bone immobilization in three animal models. The data presented here support the translation potential of SHEs in diverse settings, and pave the way for the development of self-healing materials in clinical contexts.