Effects of Bisphenol A on redox balance in red blood and sperm cells and spermatic quality in zebrafish Danio rerio.

Bisphenol-A (BPA) is a potential endocrine disruptor besides being associated with oxidative damage in several vertebrate classes. In the present study we investigated oxidative effects in erythrocytes and sperm cells as well as spermatic quality in Danio rerio exposed to 14 days at BPA concentrations of 2, 10 and 100 µg/L. Organelles structure, reactive species of oxygen (ROS) and lipoperoxidation (LPO) on erythrocytes and sperm cells were measured by flow cytometry and spermatic parameters were analyzed by the computer-assisted sperm analysis (CASA) system. For both cell types, when compared with control BPA treatment induced a significant increase in ROS and LPO production causing the membrane fluidity disorder, loss of membrane integrity and mitochondrial functionality. Furthermore, it was found a significant increase in DNA fragmentation in erythrocytes of zebrafish BPA exposed. Regarding the spermatic quality, results showed lower sperm motility in animals exposed to BPA, and alterations on velocity parameters of spermatozoa. Thus, the present study concludes that BPA affects the oxidative balance of both cell types, and that can directly affects the reproductive success of the adult Danio rerio. The sensitivity of erythrocytes to oxidative damage induced by BPA was similar to sperm cells, indicating a potential use of blood cells as indicators of oxidative damage present in fish sperm.

Mercury in freshwater, estuarine, and marine fishes from Southern Brazil and its ecological implication.

In this study, we measured the mercury concentration in 27 different fish species with high commercial value. Samples were taken from a region characterized by the diversity of aquatic environments. Mercury concentration in marine fish species varied from 30.4 to 216 ng g(-1), while in estuarine species, it varied from 12.4 to 60.3 ng g(-1). Compared to mercury concentration in marine species, none of the specimens from estuarine environment has reached a mercury concentration of 100 ng g(-1). However, mercury concentrations in species from the freshwater Patos lagoon are remarkably higher (15.3 to 462 ng g(-1)) than those from the estuarine or marine region. Even though mercury concentrations in these fish species did not exceed the maximum level (500 ng g(-1)) allowed by WHO for human consumption, they represent the main food source for sea birds and mammals coming from South Pole during their migration period.

[Immunochemical determination of saccharin]. / Immunchemische Bestimmung von Saccharin.

Saccharin is coupled to bovine serum albumin by spacers via the five membered as well as the six membered ring. Rabbits treated with these immunogenic conjugates give precipitating antibodies which are used for coating polystyrol tubes and microtiter plates. Saccharin is determined down to 0.1 mg/l, the detector reaction being performed by a saccharin horseradish peroxidase conjugate and hydrogen peroxide/1,2-diaminobenzen as substratum.

Antioxidant and toxicological effects elicited by alpha-lipoic acid in aquatic organisms.

Lipoic acid (LA) is a disulfide-containing compound derived from octanoic acid that is synthesized in mitochondria. This molecule acts as a co-factor for mitochondrial enzymes that catalyze oxidative decarboxylation reactions. Several antioxidant properties of LA enable it to be considered as an "ideal antioxidant", having diverse benefits that allow it to deal with environmental or biological stress. Some of the effects induced by LA in aquatic organisms render it suitable for use in aquaculture. However, it is necessary to determine the appropriate dose(s) to be used with different species and even organs to maximize the beneficial antioxidant and detoxifying effects and to minimize the pro-oxidant toxic effects. This review analyzes and compiles existing data from aquatic organisms in which both benefits and drawbacks of LA have been described.

Real-time fluorescence detection of RNA amplified by Q beta replicase.

Amplification of RNA probes by Q beta replicase can be used to detect a wide range of analytes with a potential sensitivity of a single molecule. A system has been developed in which Q beta amplification of midivariant-(MDV)-based RNA is measured in real time by fluorescence. This was accomplished by including a fluorescent intercalating dye, propidium iodide, in the reactions and monitoring the fluorescence change using a custom fluorometer. The time at which fluorescence is detectable above background is referred to as the "response time" and is calculated using curve-fitting algorithms. A response time is inversely and linearly proportional to the logarithm of the number of template RNA molecules which initiated the reaction. Therefore, this system permits an unknown amount of input RNA probe to be quantified through 11 orders of magnitude when compared to a standard curve. Under the described conditions with MDV RNA, the response time occurs when about 3 x 10(11) RNA molecules are synthesized and occurs within the exponential phase of the reaction, before the number of active enzyme molecules are saturated with RNA templates. This system has been used to determine the replication properties of MDV RNA reporter molecules bearing specific probe sequences and to develop hybridization assays for the clinical diagnostic field.