Effects of cadmium exposure on metabolism, antioxidant defense, immune function, and the hepatopancreas transcriptome of Cipangopaludina cathayensis.

Cadmium (Cd) is a common contaminant in aquatic environments. However, little is known about the mechanisms underlying Cd toxicity in the freshwater snail Cipangopaludina cathayensis (Heude, 1890). This study to investigate the toxic effects of Cd on the standard metabolism, antioxidant activities, immune function, and hepatopancreas transcriptome profiles of C. cathayensis. C. cathayensis was exposed to 0.25, 0.5, 1.0, or 1.5 mg/L Cd for 3 h, with results showing that Cd significantly inhibited oxygen consumption and ammonia excretion and disrupted the respiratory metabolism of C. cathayensis. In addition, the O:N ratio dropped below 7, indicating that C. cathayensis may rely exclusively on proteins as an energy source under Cd stress. To understand how Cd impacts the antioxidant activities, immune function, and transcriptional profiles, C. cathayensis were exposed to 0.5 (low exposure, L14) or 1.5 (high exposure, H14) mg/L Cd for 14 days. Our results indicate that Cd exposure leads to oxidative stress and immunosuppression, with the latter effect being larger for exposure to higher Cd concentrations. A total of 2172 differentially expressed genes (DEGs) were identified by transcriptome analysis of the hepatopancreas, of which 885 were upregulated and 1287 were downregulated. Gene ontology and KEGG analyses revealed that the DEGs in the H14 group are enriched for energy generation terms and the "oxidative phosphorylation" pathway, respectively. Therefore, up-regulation of energy metabolism may be an adaptive strategy under Cd stress. Moreover, several genes involved in antioxidant activity were downregulated, whereas genes related to reactive oxygen species generation were upregulated. In addition, many immunity-related genes were identified within the DEGs, indicating that Cd toxicity may affect immune defense. Further, DEGs in the H14 group were enriched for disease-associated pathways. Taken together, our results indicate that Cd exposure leads to metabolic disorders, oxidative stress, and immunosuppression and thus may potentially contribute to disease outbreaks.

[Effect of binocular accommodation and vergence function examinations and interventions on subjective discomfort of dry eye].

Objective: To investigate the accommodation and vergence (AV) function of patients with mild to moderate refractory dry eye symptoms, and determine the impact of relevant interventions on subjective symptoms. Methods: A total of 103 patients with dry eye disease (DED) in Zhongshan Ophthalmic Center between December 2017 and June 2019 were included. After 3-month conventional treatment, the patients entered the treatment-responsive group if ocular surface disease index (OSDI) decreased ≥12.5, and others were recruited into the refractory symptoms group. Binocular AV function, OSDI, tear break-up time (TBUT), Schirmer's test (ST) and fluorescein staining (FL) were determined in all the patients. Corrective therapy on the AV dysfunction was added in the refractory symptoms group besides the conventional therapy. The above-mentioned indexes were reexamined 8 weeks later. The incidence of AV dysfunction was compared between the refractory symptoms group and the treatment-responsive group. Moreover, the differences of OSDI and tear film stability were compared before and after the corrective therapy in the refractory symptoms group. Results: Sixty of 103 DED patients were classified into the refractory symptoms group [mean age: (27±6) years; 18 males and 25 females] and 43 into the treatment-responsive group [mean age: (30±6) years; 32 males and 28 females]. The incidence of AV dysfunction in the refractory symptom group (100%) was higher than that of the treatment responsive group (72.1%) (P<0.001). Forty patients with refractory symptoms accomplished the 8-week corrective therapy, and the OSDI score was significant improved (23.4±16.0 vs 40.6±15.7, P<0.001). However, further changes in ST, TBUT and FL were not detected in these patients (all P>0.05). Conclusions: There is a high prevalence of AV dysfunction in patients with refractory symptomatic DED. The corrective therapy on AV may improve the subjective symptoms in these patients.

Impact of static biocarriers on the microbial community, nitrogen removal and membrane fouling in submerged membrane bioreactor at different COD:N ratios.

The polyvinyl formal (PVFM) biocarrier addition in a membrane bioreactor (MBR) was evaluated at high and low carbon/nitrogen (C/N) ratio of 20.0 and 6.7. Results indicated that static biocarrier addition could enrich nitrification and denitrification bacteria, dominating by Tauera, Amaricoccus and Nitrosospira at the genus level and slightly improved the total nitrogen removal even at a low C/N ratio. The bulk sludge characteristics (such as bigger particle size, lower SMP, lower SMP P/C) were also significantly changed in the hybrid MBR (HMBR), leading to a more sustainable membrane operation. The biocarrier addition also reduced the relative abundance of Sphingobacterials_unclassified, Ohtaekwangia and Rhodocyclaceae_unclassified at the genus level, indicating less membrane fouling in the HMBR. Consequently, HMBR with static PVFM addition could partially overcome the drawback of low C/N ratio for total nitrogen removal and membrane fouling control, providing a more resilient MBR to the undesirable environment such as low C/N ratio.