Bacterial Community Structure and Diversity in the Aqueous Environment of Shihou Lake and its Relationship with Environmental Factors.

Microorganisms are sensitive to changes in the external environment and are often used as indicators to monitor and reflect water quality. Using Illumina MiSeq sequencing, the characteristics of the microbial community in Shihou Lake water at different time points were analyzed and the key environmental factors affecting the bacterial community were identified. The microbial community diversity in Shihou Lake water was rich and showed significant differences over time. The main bacterial phyla were the Cyanobacteria, Proteobacteria, Actinobacteria, Verrucomicrobia, Bacteroidetes, Chloroflexi, Planctomycetes, Firmicutes, Chlorobi, WS6 and Saccharibacteria. The relative abundance of these major phyla in the sample accounted for 97.83%-99.07% of the total abundance; Cyanobacteria had the highest relative abundance, accounting for 13.07%-44.61% of the total, and the abundance of each dominant phylum was significantly different at different time points. The Shannon and Simpson indexes showed that the diversity of each month was as follows: August > October > July > September > November. The Chao1 and Ace indexes indicated that the order of richness was: November > October > July > August > September. Beta diversity analysis found significant differences in the samples from month to month. Environmental factors such as temperature, total nitrogen, chlorophyll-a, permanganate index, nitrite, pH and ammonia nitrogen had significant effects on microbial community structure.

Effect of Chronic Exposure to Methomyl on Tissue Damage and Apoptosis in Testis of Tilapia (Oreochromis niloticus) and Recovery Pattern.

Tilapia were exposed to 0, 0.2, 2, 20, 200 µg/L methomyl for 30 days, and then transferred to methomyl-free water for 18 days. Caspase-8 in serum, apoptosis rate, microstructure and ultra-microstructure of testis were checked after methomyl exposure and at 18 days after transferring to methomyl-free water. There were no significant changes in Caspase-8 activity, apoptosis rate, and tissue structure in testis exposed to 0.2 and 2 µg/L compared with control. However, when tilapia exposed to 20 and 200 µg/L, the Caspase-8 activity and apoptosis rate were induced significantly, and tissue damage happened compared with the control. Thus it would appear 2 µg/L methomyl might be considered as the no observed adverse effect level. Recovery data showed that the effects produced by lower concentration of 20 µg/L were reversible but not at the higher 200 µg/L concentration.

Effect of methomyl on sex steroid hormone and vitellogenin levels in serum of male tilapia (Oreochromis niloticus) and recovery pattern.

Tilapia were exposed to sub-lethal concentrations of 0, 0.2, 2, 20 or 200 µg/L for 30 days, then transferred to methomyl-free water for 18 days. E2 , T, 11-KTand VTG in serum were examined. There were no significant changes in all the parameters in serum of tilapia exposed to 0.2 µg/L and 2 µg/L methomyl compared to the control. However, 20 µg/L and 200 µg/L have the potential to disrupt the endocrine system of male tilapia, as shown by its ability to increase VTG and E2 and decrease T and 11-KT in serum. Thus it would appear the no observed adverse effect level for sexual steroid hormones of methomyl is lower than 2 µg/L. Recovery data showed that the effects produced by 20µg/L were reversible but not at 200µg/L. Furthermore, the sensitivity of above parameters to methomyl followed the order of VTG>E2 >11-KT>T>GSI, suggesting VTG being the better biomarkers.

Responses and recovery pattern of sex steroid hormones in testis of Nile tilapia (Oreochromis niloticus) exposed to sublethal concentration of methomyl.

Tilapia were exposed to sublethal methomyl concentrations of 0, 0.2, 2, 20 or 200 µg/L for 30 days, and then transferred to methomyl-free water for 18 days. The sexual steroid hormones 17ß-estradiol (E2), testosterone (T), and 11-ketotestosterone (11-KT) in tilapia testes were examined at 0, 6, 12, 18, 24 and 30 days after methomyl exposure, and at 18 days after fish were transferred to methomyl-free water. There were no significant changes in the hormone parameters in testes of tilapia exposed to low concentration 0.2 and 2 µg/L methomyl compared with the controls. However, high concentration 20 and 200 µg/L methomyl had the potential to disrupt the endocrine system of male tilapia, as shown by an increase in E2 and a decrease in T and 11-KT in the testes. Thus, it would appear that the 2 µg/L methomyl might be considered the no-observed-adverse-effect level. Recovery data showed that the effects produced by the lower concentration of 20 µg/L were reversible but the effects were not reversible at the higher concentration of 200 µg/L.

Bacterioplankton community analysis in tilapia ponds by Illumina high-throughput sequencing.

The changes of microbial community in aquaculture systems under the effects of stocking densities and seasonality were investigated in tilapia ponds. Total DNAs were extracted from the water samples, 16S rRNA gene was amplified and the bacterial community analyzed by Illumina high-throughput sequencing obtaining 3486 OTUs, from a total read of 715,842 sequences. Basing on the analysis of bacterial compositions, richness, diversity, bacterial 16S rRNA gene abundance, water sample comparisons and existence of specific bacterial taxa within three fish ponds in a 4 months period, the study conclusively observed that the dominant phylum in all water samples were similar, and they included; Proteobacteria, Cyanobacteria, Bacteroidetes, Actinobacteria, Planctomycetes and Chlorobi, distributed in different proportions in the different months and ponds. The seasonal changes had a more pronounced effect on the bacterioplankton community than the stocking densities; however some differences between the ponds were more likely caused by feed coefficient than by stocking densities. At the same time, most bacterial communities were affected by the nutrient input except phylum Cyanobacteria that was also affected by the feed control of tilapia.

Responses of glutathione-related antioxidant defense system in serum of Nile tilapia (Oreochromis niloticus) exposed to sublethal concentration of methomyl and recovery pattern.

Tilapia were exposed to sublethal concentrations of 0, 0.2, 2, 20, or 200 µg/L for 30 days, and then transferred to methomyl-free water for 18 days. GST, GPx, GR, GSH, and GSSG in tilapia serum were examined at 0, 6, 12, 18, 24, and 30 days after methomyl exposure and at 18 days after transferring to methomyl-free water. There were no significant changes in antioxidants activities and contents in serum of tilapia exposed to 0.2 µg/L. Significant increases in GST, GR, GPx, and GSSG accompanied by a decrease in GSH were observed following methomyl exposure to 2, 20, or 200 µg/L, suggesting the presence of oxidative stress. Thus, it would appear the 0.2 µg/L methomyl might be considered the no observed adverse effect level. Recovery data showed that the effects produced by lower concentration of 20 µg/L were reversible but not at the higher 200 µg/L concentration.

Effects of chronic exposure of methomyl on the antioxidant system in liver of Nile tilapia (Oreochromis niloticus).

The chronic effect of methomyl on the antioxidant system in tilapia (Oreochromis niloticus) was investigated. Fish were exposed to sub-lethal concentrations of 0.2, 2, 20 and 200µgL(-1) for 30 days, and then transferred to methomyl-free water for 18 days. Hepatic antioxidant parameters, including Glutathione-S-transferase (GST), Glutathione peroxidase (GPx), Glutathione reductase (GR), Reduced glutathione (GSH) and oxidized glutathione (GSSG), were measured at 10min (day 0), 6, 12, 18, 24 and 30 days after starting the experiment and at 18 days after transferring to methomyl-free water. There were no significant changes in enzymatic activity and content of antioxidants in liver of tilapia exposed to 0.2µgL(-1) methomyl compared to controls. However, the results showed significant increases in activities of GST, GR, GPx and levels of GSSG accompanied by a decrease in GSH levels following methomyl exposure in tilapia to 2, 20 or 200µgL(-1) over the 30-day exposure period and the highest induction rates in GST, GR, GPx and GSSG were 150.87%, 163.21%, 189.76%, and 179.56% of the control respectively, and the highest inhibition rate in GSH was 50.67% of the control, suggesting the presence of oxidative stress. Thus it would appear that the 0.2µgL(-1) methomyl might be considered as the no observed adverse effect level (NOAEL). Recovery data showed that the effects produced by lower concentration of methomyl 20µgL(-1) were reversible but not at the higher 200µgL(-1) concentration.

Hepatic antioxidant enzymes SOD and CAT of Nile tilapia (Oreochromis niloticus) in response to pesticide methomyl and recovery pattern.

Hepatic antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) of Nile tilapia in response to pesticide methomyl and recovery pattern were researched by exposing tilapia to sub-lethal methomyl concentrations of 0, 0.2, 2, 20 and 200 µg/L for 30 days, and then transferred to methomyl-free water for 18 days. Hepatic SOD and CAT were measured at 10 min (day 0), 6, 12, 18, 24 and 30 days after starting the experiment and at 18 days after transferring to methomyl-free water. The results showed hepatic SOD and CAT activities in 2, 20 and 200 µg/L groups were affected significantly, however, that in 0.2 µg/L group didn't change significantly compared to control during 30-day exposure period. Thus it would appear the 0.2 µg/L methomyl might be considered the no observed adverse effect level. Recovery data showed that, for SOD, the effects produced by lower concentration of methomyl 2 µg/L were reversible but not at concentrations higher than 20 µg/L, however, for CAT, the effects produced by all the concentrations were reversible.

Effects of chronic exposure of methomyl on the antioxidant system in kidney of Nile tilapia (Oreochromis niloticus) and recovery pattern.

Tilapia were exposed to sublethal methomyl concentrations of 0, 0.2, 2, 20, or 200 µg/L for 30 d, and then were transferred to methomyl-free water for 18 d. Renal antioxidant parameters, including catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), glutathione peroxidase (GPx) , glutathione reductase (GR), total glutathione (GSH), and reduced glutathione (GSSG), were examined in tilapia at d 0, 6, 12, 18, 24, and 30 after starting the experiment and at 18 d after transferring to methomyl-free water. There were no significant changes in enzymatic activity and content of antioxidants in kidney of tilapia exposed to 0.2 µg/L methomyl compared to controls. The results showed significant increases in SOD, CAT, GST, GR, GPx, and level of GSSG accompanied by a decrease in GSH levels following methomyl exposure in tilapia to 2, 20, or 200 µg/L over the 30-d exposure period, suggesting the presence of oxidative stress. Thus, it would appear the 0.2 µg/L methomyl might be considered the no-observed-adverse-effect level (NOAEL). Recovery data showed that the effects produced by lower concentration of methomyl at 20 µg/L were reversible but not at the higher 200 µg/L concentration.

Associations between sugar sweetened beverage intake and emotional and behavioral problems in preschoolers / 中国学校卫生

Objective@#To explore the consumption of sugar sweetened beverages (SSBs) and its association with behavioral problems in Chinese preschool children, and to provide a scientific basis for the prevention of behavioral problems of children.@*Methods@#A total of 7 634 children aged 3-6 years were chosen from kindergartens in 3 cities (Yangzhou, Xuzhou, Zhenjiang) in the lower reaches of Yangtze River using method of cluster sampling during October to November in 2017. Parental or guardian questionnaires were used to obtain information regarding child consumption of SSBs. The Strengths and Difficulties Questionnaire (SDQ) was used to assess children s emotional and behavioral problems. Multivariate Logistic regression model was used to explore the association between different SSBs intake frequency and children s behavioral problems.@*Results@#A total of 5 509(72.2%) consumed SSBs less than once a day, 830(10.9%) reported SSBs consumption once a day, and 1 295(16.9%) had 2 times or more intake of sugar sweetened beverages per day. After adjusting for confounding factors including age, sex, BMI, family financial status, parental education, screen time, sleep duration, and physical activities duration, multiple Logistic regression model revealed that intake of SSBs once a day was associated with an increased risk of hyperactivity disorder ( OR =1.26, 95% CI =1.01-1.57) and SDQ total difficulties ( OR =1.44, 95% CI =1.14-1.82) in boys and with an increased risk of emotional symptoms ( OR=1.34, 95%CI =1.02-1.76), conduct problems ( OR=1.53, 95%CI =1.18-2.00), hyperactivity disorder ( OR=1.79, 95%CI =1.42-2.27) and prosocial behavior ( OR=1.48, 95%CI =1.14-1.91) in girls. Intake of SSBs≥2 times per day was associated with an increased risk of emotional symptoms ( OR=1.28, 95%CI =1.02-1.59) and SDQ difficulties ( OR=1.30, 95%CI =1.07-1.58) in boys and not with behavioral problems in girls.@*Conclusion@#Sex differences are observed with respect to the association between SSBs intake and behavioral problems in preschoolers, but no significant dose response relationship was observed. More longitudinal studies are needed to further explore the association between SSBs intake and behavioral problems in preschool children as well as the underlying physiological mechanisms in future.