[Biological Effect of Microplastics with Different Functional Groups on the Bacterial Communities and Metabolic Functions of Zebrafish (Danio rerio) Embryos].

To investigate the influences of functional groups on the biological effects caused by microplastics, the accumulation of three polystyrene microplastics (PS, PS-NH2, and PS-COOH) in zebrafish (Danio rerio) embryos were analyzed, and then the responses of metabolic functions and microbial communities in zebrafish larvae were revealed using the combination of the microbiome and metabolome methods. The results showed that all microplastics could accumulate in zebrafish with concentrations ranging from 143 to 175 µg·g-1, and there were no significant differences in the accumulation potentials among different PS treatments. Exposure to plain PS significantly affected the metabolic capacity of aminoglycosides in zebrafish larvae, whereas the metabolic processes of amino acids were affected by PS-NH2. In the PS-COOH treatment, the metabolic pathways of the tricarboxylic acid cycle, amino acids, and glycolysis in zebrafish were markedly altered. The metabolic functions of zebrafish larvae were changed by all PS microplastics, resulting in toxic effects on zebrafish, and the functional group modification of microplastics may have further enhanced these toxicities. Compared to that in the control, exposure to PS-NH2 significantly reduced the diversity of microbial communities in zebrafish larvae and increased the proportion of Proteobacteria in the composition, leading to an imbalance of the bacterial community in zebrafish and thus disrupting the metabolic functions in the fish. Therefore, the functional modifications of microplastics may significantly alter the related stresses on aquatic organisms, leading to unpredictable ecological risks.

Recent findings in Akkermansia muciniphila-regulated metabolism and its role in intestinal diseases.

The mammalian gastrointestinal tract is colonized with a majority of gut microbes, affecting host metabolism and homeostasis. Gut microbiota plays a vital role in nutrient exchange, signaling transduction between intestinal epithelial cells, and resistance to pathogen invasion. Gut microbiota is divided into mucus layer bacteria and intestinal lumen bacteria based on the colonization distribution. Akkermansia muciniphila (A. muciniphila) prefers to colonize in the intestinal mucus layer, and specifically degrades mucins to produce short-chain fatty acids, providing energy for the host and promoting colonization of the bacterium itself. Degradation of mucins prompts the host to compensate for the production of more mucins, thereby maintaining the dynamics of these proteins. In the intestinal micro-ecosystem, A. muciniphila is non-pathogenic, and its colonization with suitable abundance contributes to the development of immune system, thus promoting intestinal health. The mechanisms by which A. muciniphila bears a protective role in the host intestine are currently unclear. In this review, we summarize the microenvironment for the colonization of A. muciniphila, physiological characteristics and pathophysiological impact of A. muciniphila on intestinal diseases, such as irritable bowel syndrome, inflammatory bowel diseases, and intestinal tumors. We also provided updates for current studies on signals that A. muciniphila enhances intestinal barrier integrity and regulates immune response. Together, we conclude that A. muciniphila is a promising probiotic, which could be a microbial target for the treatment of multiple intestinal diseases.

[Community Structure and Microbial Function Responses of Biofilms Colonizing on Microplastics with Vertical Distribution in Urban Water].

Microplastics have received increasing attention worldwide due to their carrier effects. In the aquatic environment, microplastics always show a vertical distribution, which thereby may change the structure and function of the attached microbial communities. However, few studies have focused on this alteration. In this study, the structural changes and functional expression responses of the attached bacterial communities to microplastics under vertical distribution were investigated in the field combined with high-throughput sequencing technology. Polyethylene terephthalate (PET) and polyvinyl chloride (PVC) were selected as the target microplastics, which were frequently detected in the aqueous environment. The results showed that the α-diversity of bacterial communities attached to PET microplastics was much higher than that of those attached to PVC microplastics. The abundance and diversity of the bacterial communities attached to PET and PVC both increased with the increase in water depth. The α-diversity index of bacteria attached to the two typical microplastics was significantly higher in deep water (90 cm) than that in water 30 cm and 60 cm deep. The Cyanobacteria, Proteobacteria, Planctomycetes, and Verrucomicrobia were the dominant phyla in the attached bacterial communities. In addition, the deep water distinctly altered the bacteria community attached to different microplastics. The results of functional prediction showed that the functional expression of pyrimidine metabolism, amino sugar and nucleotide sugar metabolism, starch and sucrose metabolism, and aminoacyl-tRNA biosynthesis were positively correlated with water depth. In addition, the functional responses of the bacterial communities attached to microplastics were also increased, especially in deep water. Further, the bacterial functions of those attached to PET were significantly higher than that of those attached to PVC. This suggests that both the microplastic polymer and the water depth could affect the structure and function of the attached bacterial communities and that the water depth was more important, which may be related to the difference in the vertical distribution of light and turbidity. The results of this study provide a new insight into the microbial response to and environmental risk of microplastic pollution.

Single and combined effects of estrone and 17ß-estradiol on male goldfish.

OBJECTIVE: To assess the single and combined effects of estrone (E1) and 17ß-estradiol (E2) on goldfish (Carassius auratus). METHODS: Batch tests were conducted. Serum levels of vitellogenin (VTG) and E2, gonadosomatic indices (GSI), gonadal DNA damage and liver 7-ethoxyresorufin-O-deethylase (EROD) activity were measured after exposure for 14 days. RESULTS: The VTG level increased significantly in a concentration-dependent manner. The serum E2 level was significantly higher and the GSI level was significantly lower in goldfish after exposed to the 3 drugs. DNA damage occurred in treated samples and EROD activity was significantly suppressed 7 days after exposure. The joint effect of E1 and E2 was additive with regard to VTG induction. CONCLUSION: The results of our study highlight a series of effects of steroidal estrogens on goldfish. Further study is needed to confirm their effect as a whole.