A climate for contemporary evolution

A new study of divergence in freshwater fish provides strong evidence of rapid, temperature-mediated adaptation. This study is particularly important in the ongoing debate over the extent and significance of evolutionary response to climate change because divergence has occurred in relatively few generations in spite of ongoing gene flow and in the aftermath of a significant genetic bottleneck, factors that have previously been considered obstacles to evolution. Climate change may thus be more likely to foster contemporary evolutionary responses than has been anticipated, and I argue here for the importance of investigating their possible occurrence.     

Evaluation of Nisin F in the Treatment of Subcutaneous Skin Infections, as Monitored by Using a Bioluminescent Strain of Staphylococcus aureus

The potential of nisin F as an antimicrobial agent in treating subcutaneous skin infections was tested in vivo by infecting C57BL/6 mice with a bioluminescent strain of Staphylococcus aureus (Xen 36). Strain Xen 36 has the luxABCDE operon located on a native plasmid. Mice were grouped into four groups: Infected with strain Xen 36 and treated with nisin F, infected with strain Xen 36 and treated with saline (placebo), not infected and treated with nisin (control) and not infected and not treated (control). The immune systems of the mice were suppressed with deksamethasone. Mice were treated with either nisin F or sterile physiological saline 24 and 48 h after infection with subcutaneously injected S. aureus Xen 36 (4 × 10⁶ CFU). Histology and bioluminescent flux measurements revealed no significant difference between infected mice treated with nisin and saline, respectively. However, infected mice treated with nisin F had an increased number of polymorphonuclear cells when compared with infected mice treated with saline. Also, not infected mice treated with nisin F had an influx of polymorphonuclear cells. Nisin F is thus ineffective in combating deep dermal staphylococcal infections. The apparent immune modulation of nisin when subcutaneously injected has to be investigated.     

Acrylonitrile inhalation in rats: II. Excretion of thioethers and thiocyanate in urine

In male Wistar rats, the inhalation exposure to acrylonitrile (AN), 271 mg X m-3, 8 hours a day, 5 days a week, did not affect protein sulfhydryl concentration in liver and blood and decreased glutathione concentration in the liver, but not in the brain at the end of the fifth exposure. The urinary excretion of the main AN metabolites, thioethers (AN-mercapturic acids) and thiocyanate was proportional to the inhaled AN concentration (57, 125, 271 mg X m-3, respectively) in a single exposure for 12 hours, and their mutual ratio was greatly different from that after injection of AN. The results revealed that the urinary excretion of thioethers is a very sensitive and dose-related indicator of exposure to AN and extrapolation of the results indicates that the exposure to AN concentration below 10 mg X m-3 could thus be demonstrated.