ABSTRACT
Pannon White (n=12) male rabbits (weight: 4050 to 4500 g, age: 9 months) received 2 ml of a suspension containing purified T-2 toxin by gavage for 3 days. The daily toxin intake was 4 mg/animal (0.78 to 0.99 mg/kg body weight (BW)). Control animals (n=12) received toxin-free suspension for 3 days. Since a feed-refusal effect was observed on the second day after T-2 administration, a group of bucks (n=10) were kept as controls (no toxin treatment) but on a restricted feeding schedule, that is, the same amount of feed was provided to them as was consumed by the exposed animals. On day 51 of the experiment (i.e. 48 days after the 3-day toxin treatment), semen was collected, and pH, concentration, motility and morphology of the spermatozoa, as well as concentration of citric acid, zinc and fructose in the seminal plasma, were measured. After gonadotropin-releasing hormone (GnRH) analogue treatment, the testosterone level was examined. One day of T-2 toxin treatment dramatically decreased voluntary feed intake (by 27% compared to control, P<0.05) and remained lower (P<0.05) during the first 2 weeks after the withdrawal of the toxin. BW of the contaminated rabbits decreased by 88% on days 17 and 29 compared to controls (P<0.05). No effect of toxin treatment was detected on pH and quantity of the semen or concentration of spermatozoa. The ratio of spermatozoa showing progressive forward motility decreased from 65% to 53% in the semen samples of toxin-treated animals compared to controls (P>0.05). The ratio of spermatozoa with abnormal morphology increased (P<0.05) in the ejaculates collected from the toxin-treated animals. T-2 toxin applied in high doses decreased the concentration of citric acid in seminal plasma (P<0.05). No effect of T-2 toxin on the concentrations of the other seminal plasma parameters (fructose and zinc) was observed. T-2 toxin decreased the basic testosterone level by 45% compared to control (P<0.01) and resulted in lower (P<0.05) GnRH-induced testosterone concentration. Feed restriction, that is, less nutrient intake, resulted in more morphologically abnormal spermatozoa in the semen, but it did not cause significant loss in BW, motility of the spermatozoa, composition of the seminal plasma or testosterone concentration--its effect needs further examination.
ABSTRACT
A possible sink for divalent lead in the environment is clays such as montmorillonite that have cation exchange capacities. To assess the reaction, a calcium-montmorillonite was mixed with lead perchlorate solutions of varying concentrations and at various pH's. The recovered solids were studied by a variety of techniques (X-ray photoelectron and infrared spectroscopy, scanning electron microscopy, and atomic force microscopy) to determine what, if any, alterations occurred. The ion exchange of lead for calcium reduced the hydrated water in the clay, and evidence for proton-lead ion exchange at the edges of the sheets was observed. Evidence for a second, unexpected, reaction was also observed. Small spots (0.2 to 1 microm) of lead enrichment were observed on the surface of clay particles. They were also observed on clays recovered from the sediment of a Hungarian lake. The results show that lead ions are adsorbed onto montmorillonite by two processes: cation exchange and nano- and microparticle production. Cation exchange leads to the even distribution of the ions, while the production of spots causes the enrichment of lead ions. The production of these particles is not expected from the thermodynamic properties of the solution and cannot be observed in the absence of clay.
