Nitrogen Removal in Oligotrophic Reservoir Water by a Mixed Aerobic Denitrifying Consortium: Influencing Factors and Immobilization Effects.

Nitrogen pollution in reservoirs has received increasing attention in recent years. Although a number of aerobic denitrifying strains have been isolated to remove nitrogen from eutrophic waters, the situation in oligotrophic water environments has not received significant attention. In this study, a mixed aerobic denitrifying consortium screened from reservoir samples was used to remove nitrogen in an oligotrophic denitrification medium and actual oligotrophic source water. The results showed that the consortium removed 75.32% of nitrate (NO3--N) and 63.11% of the total nitrogen (TN) in oligotrophic reservoir water during a 24-h aerobic cultivation. More initial carbon source was helpful for simultaneous removal of carbon and nitrogen in the reservoir source water. NO3--N and TN were still reduced by 60.93% and 46.56% at a lower temperature (10 °C), respectively, though the rates were reduced. Moreover, adding phosphorus promoted bacterial growth and increased TN removal efficiency by around 20%. The performance of the immobilized consortium in source water was also explored. After 6 days of immobilization, approximately 25% of TN in the source water could be removed by the carriers, and the effects could last for at least 9 cycles of reuse. These results provide a good reference for the use of aerobic denitrifiers in oligotrophic reservoirs.

SUMO-conjugating enzyme UBC9 promotes proliferation and migration of fibroblast-like synoviocytes in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease with high morbidity and mortality. Fibroblast-like synoviocytes (FLS) in the synovial tissues play critical roles in joint destruction. Recent studies implicate the sumoylation in the regulation of the inflammation and arthritis. Thus, we explored whether SUMO-conjugating enzyme UBC9 is involved in the progression of RA using a mouse collagen-induced arthritis (CIA) model. The effects of UBC9 siRNA on cell invasion and migration in human RA-FLS were also assessed in vitro. Treatment with siRNA against UBC9 for 3 weeks reduced the arthritis score and joint destruction. The expression of SUMO-1 and UBC9 protein in CIA joints was inhibited by UBC9 knockdown. Serum levels of anti-collagen (CII) antibodies, vascular endothelial growth factor A (VEGF-A), matrix metalloproteinases (MMP)-3, and MMP-9 were also decreased in CIA mice. In vitro, UBC9 silencing inhibited the secretion of VEGF-A, MMP-3, and MMP-9 from TNF-α-stimulated human RA-FLS. TNF-α-induced RA-FLS proliferation and migration were significantly attenuated by UBC9 knockdown. These findings indicate that SUMO-conjugating enzyme UBC9 promotes proliferation and migration of fibroblast-like synoviocytes in rheumatoid arthritis. Inhibition of UBC9 activity may be a viable therapeutic target in amelioration of disease progression in RA by attenuating FLS proliferation, migration, and invasion.