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The mechanisms behind nitrogen removal by the submersed macrophyte-biofilm complex in wetlands remain to be fully elucidated. This study investigated the role of Myriophyllum spicatum and the biofilm on their leaves in nitrogen removal in mesocosm experiments. 15N tracking showed that 61.9% and 30% of the 15N, respectively, was removed from the system and assimilated by the macrophyte-biofilm complex after loading with 5.4 mg L−115N labelled NH 4 + for 17 days. Nitrogen budget results showed that about 0.2%, 0.2% and 3.6% of the nitrogen were emitted as water-, HCl- and NaOH-soluble nitrogen-gas species, respectively. Bacteria (76.7–91.8%) were the predominant domain in all samples, followed by eukaryotes (8.0–23.0%), archaea and viruses. Network analyses showed that there were positive- and negative-correlative relationships among nitrogen-cycling genes and nitrifiers and denitrifiers. Our data highlight the important role of biofilm on submersed macrophytes for nitrogen removal. Image 1 • M. spicatum restoration promoted nitrogen removal in constructed wetlands (mesocosm scale). • The biofilms had a higher competitiveness for waterborne nitrogen than M. spicatum. • Bacteria were the most dominant domain, followed by eukaryotes, archaea and viruses. • There were complex interactions among nitrogen-cycling genes and genera. The biofilms had a higher competitiveness for nitrogen than M. spicatum and there were complex interactions among nitrogen-cycling genes and genera in biofilms. [ABSTRACT FROM AUTHOR]

This study investigated the alterations in biomass, nutrients and dissolved organic matter concentration in overlying water and determined the bacterial 16S rRNA gene in biofilms attached to plant residual during the decomposition of Myriophyllum verticillatum . The 55-day decomposition experimental results show that plant decay process can be well described by the exponential model, with the average decomposition rate of 0.037 d −1 . Total organic carbon, total nitrogen, and organic nitrogen concentrations increased significantly in overlying water during decomposition compared to control within 35 d. Results from excitation emission matrix-parallel factor analysis showed humic acid-like and tyrosine acid-like substances might originate from plant degradation processes. Tyrosine acid-like substances had an obvious correlation to organic nitrogen and total nitrogen ( p < 0.01). Decomposition rates were positively related to pH, total organic carbon, oxidation-reduction potential and dissolved oxygen but negatively related to temperature in overlying water. Microbe densities attached to plant residues increased with decomposition process. The most dominant phylum was Bacteroidetes (>46%) at 7 d, Chlorobi (20%–44%) or Proteobacteria (25%–34%) at 21 d and Chlorobi (>40%) at 55 d. In microbes attached to plant residues, sugar- and polysaccharides-degrading genus including Bacteroides , Blvii28 , Fibrobacter , and Treponema dominated at 7 d while Chlorobaculum , Rhodobacter , Methanobacterium , Thiobaca , Methanospirillum and Methanosarcina at 21 d and 55 d. These results gain the insight into the dissolved organic matter release and bacterial community shifts during submerged macrophytes decomposition. [ABSTRACT FROM AUTHOR]

Though aquatic macrophytes play an important role in wetlands, their effects on bacteria community structures in biofilms and sediments are far from clear. In the present study, bacterial communities were investigated in biofilm attached to leaves, stems and roots of aquatic macrophytes ( Myriophyllum verticillatum , Nymphoides peltatum and Trapa japonica ) and in vertical sediment cores from vegetated and unvegetated areas in a wetland located in Lake Hongze. The densities of microbes and epiphytic algae in biofilms were higher on leaves of M. verticillatum than those of two floating macrophytes. Phyla Proteobacteria, Bacteroidetes, Chloroflexi, Firmicutes and Verrucomicrobia were detected in both biofilms and sediments. As revealed by cluster analysis and principal component analysis, differences in structures of microbial communities were detected between biofilms and sediments and between vegetated and unvegetated sediments. The potential roles of nitrifying- and denitrifying- bacteria in sediments with respect to those in biofilms were discussed. These results highlight that the restoration of aquatic macrophytes can increase bacteria diversity and the surface and quantity of biofilms and therefore bacteria diversity. These data provide useful information for further understanding the role of aquatic macrophyte-biofilm system in wetlands in future. [ABSTRACT FROM AUTHOR]

Red light (RL) can improve egg production in Jinghai Yellow hens. Circular RNAs (circRNAs) are novel, non-coding RNAs, but the molecular mechanism underlying circRNA function during follicular development in hens under monochromatic light has not been established. Herein, we compared expression profiles of granulosa cells (GCs) from small yellow follicles (SYFs) from hens under RL and white light (WL). A total of 2,468 circRNAs were identified, of which 22 were differentially expressed (DE) in the RL and WL groups. DE circRNA host genes were enriched in ovarian steroidogenesis, and MAPK and PI3K-Akt signaling pathways. Furthermore, DE circRNA_0320 and circRNA_0185 interacted with miR-143-3p, which targets the follicle-stimulating hormone receptor and is essential for GC differentiation and follicle development. These findings will facilitate further analysis of the molecular mechanism leading to GC development in hens raised under monochromatic light, which could lead to increased egg production. [ABSTRACT FROM AUTHOR]

Epiphytic bacteria on submerged macrophytes play important roles in the nutrient cycle in freshwater ecosystems. However, little is known about the composition and role of epiphytic bacteria during the decomposition of submerged macrophytes. In this study, the alterations in epiphytic bacterial composition, abundances of nitrogen cycle-related genes and nutrient release were investigated in a 56-day decomposition process of Potamogeton malaianus. The total reduced biomass was positively related to the contents of carbon, nitrogen and phosphorus released from plant residues. Nutrient released from plant litter showed a positively effect on the concentrations of carbon, nitrogen and phosphorus in the overlying water (p < 0.01). The carbon, phosphorus and nitrogen decreased with decomposition process in both plant debris and overlying water. Humic acid-like substances were the main component of dissolved organic matter in the conditioning stage, whereas fulvic acid-like substances dominated in the fragmentation stage. Results from network analysis and canonical correspondence analysis showed dominant bacterial clades changed with decomposition process. Bacteroidetes was the most abundant phylum in the leaching stage and Spirochaetes , Chlorobi, and Bacteroidetes dominated in the conditioning stage, while Chlorobi dominated in the fragmentation stage. The highest abundance of c norB and nosZ were detected in the leaching and fragmentation stage, respectively. Bacterial denitrification contributed to nitrogen removal and might be promoted by high ORP and DOC concentration. Our results indicate that epiphytic bacterial community shift drived the metabolism of nutrients C, N, and S during the decomposition of P. malaianus. • Nutrient release is related to the decomposition stages of P. malaianus. • Degradable organic carbon and ORP are key factors affecting the denitrification. • Epiphytic bacteria drive the nutrient cycle during litter decomposition. • Combined dynamics of C, N, and S was found during the nutrient cycle. [ABSTRACT FROM AUTHOR]