Cyto-histological and morpho-physiological responses of common duckweed (Lemna minor L.) to chromium

Along with cadmium, lead, mercury and other heavy metals, chromium is an important environmental pollutant, mainly concentrated in areas of intense anthropogenic pressure. The effect of potassium dichromate on Lemna minor populations was tested using the growth inhibition test. Cyto-histological and physiological analyses were also conducted to aid in understanding the strategies used by plants during exposure to chromium. Treatment with potassium dichromate caused a reduction in growth rate and frond size in all treated plants and especially at the highest concentrations. At these concentrations the photosynthetic pathway was also altered as shown by the decrease of maximum quantum yield of photosystem II and the chlorophyll b content and by the chloroplast ultrastructural modifications. Starch storage was also investigated by microscopic observations. It was the highest at the high concentrations of the pollutant. The data suggested a correlation between starch storage and reduced growth; there was greater inhibition of plant growth than inhibition of photosynthesis, resulting in a surplus of carbohydrates that may be stored as starch. The investigation helps to understand the mechanism related to heavy metal tolerance of Lemna minor and supplies information about the behavior of this species widely used as a biomarker

Sequestration of antibiotic by magnetic nanoparticles and potential application for water remediation

Tons of antibiotics are produced annually worldwide for consumption by humans or use in the treatment of animals, including fish. The release and presence of antibiotics in the environment is a hot topic, which was firstly highlighted in the US in the 70's and almost a decade later in England. Yet, it was in the mid-90s, with the progress of analytical techniques, that the knowledge about environmental contamination caused by these compounds excelled considerably. Most of these antibiotics are synthesized in order to remain stable in the environment for long periods, in such way their curative effect is guaranteed in time. Paradoxically, the same characteristics are responsible for their toxicity by bioaccumulation in aquatic and terrestrial ecosystems. Some antibiotics are systematically used in farms for animal care and prophylaxis of diseases. These compounds are released later in the environment through the feces and urine and can therefore easily reach waterways. Recent studies have shown concentrations of different types of antibiotics in wastewater, surface waters, seawater, groundwater and drinking water. The scientific community clearly states that the presence of pharmaceutical products cause adverse effects not only to aquatic ecosystems but also to human health. Especially antibiotics and antiparasitic drugs are abundantly used for veterinary purposes. Sulfonamides, fluoroquinolones, tetracyclines are frequently found in surface water at concentrations in the mg-ng L-1 range. Some of these compounds are quickly degraded, while others (such as oxytetracycline) persist and remain active in the environment for long periods. Better, and more effective, administration techniques of these molecules as well as the development of bioremediation techniques are thus considered of primary importance. At this regard, nanomaterials are looked with great interest since they have been developed for technical applications due to their extremely small size (1 to 100 nm), which supposes much larger surface to volume ratio compared with conventional particles and provides them with unique physical and chemical properties

Nanotechnologies applied to antibiotic delivery in Zebrafish (Danio rerio)

Tons of drugs are produced annually worldwide for consumption by humans or use in the treatment of animals. The release and presence of drugs in the environment is a highly hot topic, which was firstly highlighted in the US in the 70's and almost a decade later in England. Yet, it was in the mid-90s, with the progress of analytical techniques, that the knowledge about environmental contamination caused by these compounds excelled considerably. Most of these drugs are poorly metabolized by animals after ingestion and a fraction ranging from 25% to 75% may be released into the environment after consumption Rivas et al. (2011). Recent studies have shown concentrations of different types of drugs in wastewater, surface waters, in sea water, groundwater and drinking water equal to mg-ng L-1. The scientific community clearly states that the presence of pharmaceutical products cause adverse effects not only to aquatic ecosystems but also to human health. Especially antibiotics and antiparasitic drugs are abundantly used for veterinary purposes. Oxytetracycline is one of the most commonly, wide spectrum, antibiotics used, typically administered orally, (incorporated into pellet feed) or via water. This antibiotic is characterized by a poor adsorption (25 to 30%) that often results in the production of large amounts of wastes. The release of these wastes into the aquatic environment can cause serious threat to aquatic organisms. As a consequence, a better management of antibiotic administration is considered of primary importance. At this regard, nanotechnologies, and in particular nanoparticles (NP) are looked with great interest because of their unique chemical-physical properties that make them ideal for several biomedical applications, including drug delivery Piccinetti et al. (2014). Piccinetti CC., Montis C., Bonini M., et al. 2014. Transfer of Silica-Coated Magnetic (Fe3O4) Nanoparticles Through Food: A Molecular and Morphological Study in Zebrafish. Zebrafish 11: 567-579