pheophytin-a and florfenicol

Antibiotics and microplastics (MPs) are two emerging pollutants in agroecosystems, however the effects of co-exposure to antibiotics and MPs remain unclear. The toxicity of florfenicol (FF) and polystyrene microplastics (PS-MPs) on rice seedlings was investigated. FF and PS-MPs caused colloidal agglomeration, which changed the environmental behavior of FF. FF inhibited rice growth and altered antioxidant enzyme (superoxide dismutase, peroxidase, and catalase) activities, leading to membrane lipid peroxidation; impaired photosynthetic systems, decreased photosynthetic pigments (Chlorophyll a, Chlorophyll b, and carotene), chlorophyll precursors (Proto IX, Mg-Proto IX, and Pchlide), photosynthetic and respiratory rates. The key photosynthesis related genes (PsaA, PsaB, PsbA, PsbB, PsbC, and PsbD) were significantly down-regulated. The ultrastructure of mesophyll cells was destroyed with chloroplast swelling, membrane surface blurring, irregular thylakoid lamellar structure, and number of peroxisomes increased. PS-MPs mitigated FF toxicity, and the IBR index values showed that 10 mg∙L

Topics: Anti-Bacterial Agents; Chlorophyll A; Hydroponics; Microplastics; Oryza; Oxidative Stress; Plastics; Polystyrenes; Seedlings

Florfenicol (FF) and thiamphenicol (TAP) are two typical pharmaceuticals used widely as therapeutica antibiotic agents in aquaculture. However, little is known about the potential adverse effects of these two antibiotics on non-target organisms in the aquatic ecosystem. In this study we investigated the effects of FF and TAP on photosynthesis and the antioxidant system of the cyanobacteria Microcystis flos-aquae. Over a concentration range of 0.001-1μg/L, the results showed that both FF and TAP significantly increased the chlorophyll a content of M. flos-aquae, while the superoxide dismutase (SOD) activity, catalase (CAT) activity and the levels of malondialdehyde (MDA) changed slightly. In contrast, the chlorophyll a content of M. flos-aqua was significantly inhibited (p<0.01) at high concentrations (>1μg/L) of FF and TAP, reaching a 46% inhibition level at 50μg/L FF and 56% inhibition at 100μg/L TAP. At the same time, the activities of SOD and CAT along with MDA content also increased significantly (p<0.01), indicating that the high concentrations of both FF and TAP led to oxidative stress in the algae. In addition, the M. flos-aquae fluorescence parameters (Fv/Fm, Fv/Fo, alpha, ETRmax and Ik) increased with increasing concentration of both FF and TAP, which may be the result of the increasing photoprotection capacity.

Topics: Algal Proteins; Antioxidants; Catalase; Chlorophyll; Chlorophyll A; Environmental Exposure; Lipid Peroxidation; Lipid Peroxides; Malondialdehyde; Microcystis; Oxidative Stress; Photosynthesis; Superoxide Dismutase; Thiamphenicol; Water Pollutants, Chemical

Aquaculture facilities are a potential source of antibiotics to the aquatic ecosystems. The presence of these compounds in the environment may have deleterious effects on non-target aquatic organisms such as microalgae, which are often used as biological indicators of pollution. Therefore, the toxicity induced by chloramphenicol (CHL), florphenicol (FLO) and oxytetracycline (OTC), three antibiotics widely used in aquaculture, on the marine microalga Tetraselmis suecica was evaluated. Growth inhibition and physiological and biochemical parameters were analysed. All three antibiotics inhibited growth of T. suecica with 96 h IC50 values of 11.16, 9.03 and 17.25 mg L(-1) for CHL, FLO and OTC, respectively. After 24 h of exposure no effects on growth were observed and cell viability was also unaffected, whereas a decrease in esterase activity, related with cell vitality, was observed at the higher concentrations assayed. Photosynthesis related parameters such as chlorophyll a cellular content and autofluorescence were also altered after 24 h of antibiotics addition. It can be concluded that T. suecica was sensitive to the three antibiotics tested.

Topics: Anti-Bacterial Agents; Aquaculture; Cell Proliferation; Cell Survival; Chloramphenicol; Chlorophyll; Chlorophyll A; Microalgae; Oxytetracycline; Thiamphenicol; Toxicity Tests; Water Pollutants, Chemical