Search

Antibiotics have recently gained attention because they are emerging environmental pollutants with obesogenic properties. In this study, Drosophila melanogaster were exposed to sulfamethoxazole (SMX), a sulfonamide antibiotic, and the effects were measured on circadian rhythm (represented by the eclosion rhythm), lipid metabolism, and microbiota. Circadian rhythm disorder was considered due to its connection with lipid metabolism and microbiota in association with obesity. SMX decreased the proportion of adult flies that eclosed in the morning (AM adults) and increased the proportion of PM adults. Moreover, SMX increased the body weight of PM adults, indicating that SMX exposure caused dysrhythmia in eclosion together with obesity. In measurements of key metabolites and metabolic enzymes, SMX exposure stimulated 3 indices in AM adults and 10 indices in PM adults. In AMP-activated protein kinase and insulin/IGF-1 signaling pathways, SMX upregulated six genes in AM adults and nine genes in PM adults. Finally, microbiota analysis demonstrated that SMX increased the Firmicutes/Bacteroides ratios (F/B) by 79.6- and 5.8-fold compared to concurrent controls in AM and PM adults. Collectively, these results suggest that SMX showed obesogenic effects accompanied with dysrhythmia and disturbances in lipid metabolism and microbiota. Further studies on the intrinsic connection are needed.

Increasing concerns are earned on the multigenerational hazards of antibiotics due to the connection between their mother-children transfer via cord blood and breast milk and obesity in the children. Currently, Caenorhabditis elegans was exposed to sulfamethoxazole (SMX) over 11 generations (F0-F10). Indicators of obesogenic effects and gene expressions were measured in each generation and also in T11 to T13 that were the offspring of F10. Biochemical analysis results showed that SMX stimulated fatty acids in most generations including T13. The stimulation was resulted from the balance between enzymes for fatty acid synthesis (e.g., fatty acid synthetase) and those for its consumption (e.g., fatty acid transport protein). Gene expression analysis demonstrated that the obesogenic effects of SMX involved peroxisome proliferator activated receptors (PPARs, e.g., nhr-49) and insulin/insulin-like signaling (IIS) pathways (e.g., ins-1, daf-2 and daf-16). Further epigenetic analysis demonstrated that SMX caused 3-fold more H3K4me3 binding genes than the control in F10 and T13. In F10, the most significantly activated genes were in metabolic and biosynthetic processes of various lipids, nervous system and development. The different gene expressions in T13 from those in F10 involved development, growth, reproduction and responses to chemicals in addition to metabolic processes., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Negative effects of environmental antibiotics on non-target organisms were observed in studies at various levels of the biological organization. Yet, studies combining the effects at multiple levels were required to interpret their ecological frequencies in a broader context. Currently, effects of sulfamethoxazole (SMX) was studied on the amphipod Hyalella azteca which is important in ecological stability. At the biochemical level, effects on the antioxidant capacities showed stimulation with an inverse U-shaped change over the concentrations. The stimulation was greater in male than in females. Effects on the oxidative stress showed a U-shaped change which included stimulation and inhibition in males, and solely stimulation in females. The stimulation was less in males than in females. Effects on acetylcholinesterase (AChE) activities in both sexes were well correlated with those on oxidative stress (p < 0.05). At the individual level, effects on the body weight showed an inverse U-shaped change over concentrations, and the stimulation was greater in males than in females. The stimulations were significantly correlated with the male oxidative stress (p < 0.01), and male (p < 0.1) and female AChE activities (p < 0.05). Effects of SMX on the pre-copulation behavior also showed an inverse U-shaped change which correlated with male and female antioxidant capacities (p < 0.05) and the male body weight (p < 0.05). At the population level, effects on the reproduction showed an inverse U-shaped change over concentrations, and they significantly correlated with the male body weight (p < 0.05) and the pre-copulation behavior (p < 0.05). Summing up, SMX provoked simultaneous disturbances on the amphipod at multiple levels with sex-dependent responses., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Trans-generational effects are increasingly used to indicate long-term influences of environmental pollutants. However, such studies can be complex and yield inconclusive results. In this study, the trans-generational effects of sulfamethoxazole (SMX) on Caenorhabditis elegans on lifespan, reproduction and population growth were tested for 7 consecutive generations, which included gestating generation (F0), embryo-exposed generation (F1), germline-exposed generation (F2), the first non-exposed generation (F3) and the three following generations (F4-F6). Results showed that lifespan was significantly affected by embryo exposure (F1) at 400µm SMX with a value as low as 47% of the control. The reproduction (a total brood size as 49% of the control) and population growth (81% of the control) were significantly affected in germline exposure (F2). Lifespan and reproduction were severely inhibited in non-exposed generations, confirming the real trans-generational effects. Notably, initial reproduction and reproduction duration showed opposite generation-related changes, indicating their interplay in the overall brood size. The population growth rate was well correlated with median lethal time, brood size and initial reproduction, which indicated that the population would increase when the nematodes lived longer and reproduced more offspring within shorter duration., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Sulfamethoxazole (SMX) is one of the most common detected antibiotics in the environment. In order to study whether SMX can affect behavior and growth and whether these effects could be transferred to the progeny, Caenorhabditis elegans was exposed at environmentally relevant concentrations for 24, 48, 72 and 96 hr, respectively. After exposure, the exposed parent generation (P0) was measured for behavior and growth indicators, which were presented as percentage of controls (POC). Then their corresponding unexposed progeny (F1) was separated and measured for the same indicators. The lowest POC for P0 after 96 hr-exposure at 100 mg/L were 37.8%, 12.7%, 45.8% and 70.1% for body bending frequency (BBF), reversal movement (RM), Omega turns (OT) and body length (BL), respectively. And F1 suffered defects with the lowest POC as 55.8%, 24.1%, 48.5% and 60.7% for BBF, RM, OT and BL, respectively. Defects in both P0 and F1 showed a time- and concentration-dependent fashion and behavior indicators showed better sensitivity than growth indicator. The observed effects on F1 demonstrated the transferable properties of SMX. Defects of SMX at environmental concentrations suggested that it is necessary to perform further systematical studies on its ecological risk in actual conditions.