Micronucleus test and comet assay in erythrocytes of the Amazonian electric fish Apteronotus bonapartii exposed to benzene

In this study we address the genotoxicity and putative mutagenic effects of benzene (BZN) in the erythrocytes of the electric fish Apteronotus bonapartii (Gymnotiformes, Apteronotidae) using the micronucleus test (MN) and comet assay, under controlled laboratory conditions. Electric fish were collected in the Solimões River, Manaus-AM, Brazil, and the specimens were exposed to 10 and 25 ppm concentrations of BZN, in 150L tanks. Blood samples were collected at 0 (T0), 24, 48, 72 and 96 hours of exposure. For the concentration of 10 ppm BZN, the number of comets was significantly higher than T0 levels after exposure of 48 hours, whereas the nuclear abnormalities (including MN) did not show any increase in relation to the controls (T0) up to 96 hours. For the 25 ppm BZN, MN rates presented a significant increase after 72 hours, whereas other types of nuclear abnormalities increased in frequency after various exposure times, ranging from 24 to 72 hours. The number of comets increased significantly from 24 hours onwards for 25 ppm BZN. Both assays also showed a gradual increase in the number of damaged cells after longer exposure periods, indicating a time-dependent effect, especially at the highest BZN concentrations tested. This investigation reinforces the potential use of the endemic South American electric fish as a suitable genotoxicity biological model for biomonitoring purposes in the Amazon. Keywords: Comet assay, Micronucleus test, Apteronotus bonapartii, Benzene, Biomonitoring, Electric fish, Amazo

A METHOD TO EVALUATE INTRACYCLE PROPULSIVE FORCE AND BODY VELOCITY CHANGES

Propulsive force in swimming show a periodical variation during each strike, resulting in either acceleration or deceleration of the body. Development of a computer-based system to measure force and velocity during- semi-tethered swinimill-g enables us to quantify intracycle variations and obtain an individual diagnosis of swimmiilg proficiency. The testing apparatus consists of a 314" shaft supported oh radial bearings in which a 4" barrel is welded. The measurements were effectuated' using 15 meters of stainless steel light cable coiled around the barrel, with its free end connected to a harness belt attached to the swimmer's waist. The force generated against the cable by the swimmer when moving away from the apparatus was sensed by a force transducer located between the harness belt and the cable, and converted to a proportional voltage output. The data is relayed to a computer through an a/d converter and processed to calculate force for each swimming stroke or for any given time period. Swimming velocity was measured based on the rotational velocity of the wheel. An adapted potentiometer was attached to an end of the shaft. The angle signal is also interfaced and converted to a digital signal. At the other end an electromagnetic brake was mounted, to prevent turning velocity of the wheel to fluctuate due to its own inertia, keeping the cable always stretched. A constant force of 30 N was necessary to initiate the rolling of the barrel. This procedure does not primarily aim at the quantitative acquisition of the overall velocity and force values, but at a qualitative evaluation of the intracycle fluctuations

On spin-1 massive particles coupled to a Chern-Simons field

We study spin one particles interacting through a Chern-Simons field. In the Born approximation, we calculate the two body scattering amplitude considering three possible ways to introduce the interaction: (a) a Proca like model minimally coupled to a Chern-Simons field, (b) the model obtained from (a) by replacing the Proca's mass by a Chern-Simons term and (c) a complex Maxwell-Chern-Simons model minimally coupled to a Chern-Simons field. In the low energy regime the results show similarities with the Aharonov-Bohm scattering for spin 1/2 particles. We discuss the one loop renormalization program for the Proca's model. In spite of the bad ultraviolet behavior of the matter field propagator, we show that, up to one loop the model is power counting renormalizable thanks to the Ward identities satisfied by the interaction vertices.Comment: 14 pages, 5 figures, revte