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Developmental time is a trait of great relevance to fitness in all organisms. In holometabolous species that occupy ephemeral habitat, like Drosophila melanogaster, the impact of developmental time upon fitness is further exaggerated. We explored the trade-offs surrounding developmental time by selecting 10 independent populations from two distantly related selection treatments (CB_1-5 and CO_1-5) for faster development. After 125 generations, the resulting accelerated populations (ACB_1-5 and ACO_1-5) displayed net selection responses for development time of -33.4 hours (or 15%) for ACB and -38.6 hours (or 17%) for ACO. Since most of the change in egg-to-adult developmental time was accounted for by changes in larval duration, the “accelerated” larvae were estimated to develop 25-30% faster than their control/ancestor populations. The responses of ACB and ACO lines were remarkably parallel, despite being founded from populations evolved independently for more than 300 generations. On average, these “A” populations developed from egg to adult in less than eight days and produced fertile eggs less than 24 hours after emerging. Accelerated populations showed no change in larval feeding rate, but a reduction in pupation height, the latter being a trait relating to larval energetic expenditure in wandering prior to pupation. This experiment demonstrates the existence of a negative evolutionary correlation between preadult developmental time and viability, as accelerated populations experienced a severe cost in preadult survivorship. In the final assay generation, viability of accelerated treatments had declined by more than 10%, on average. A diallel cross demonstrated that the loss of viability in the ACO lines was not due to inbreeding depression. These results suggest the existence of a rapid development syndrome, in which the fitness benefits of fast development are balanced by fitness costs resulting from reduced preadult survivorship, marginal larval storage of metabolites, and reduced adult size.

Ralstonia solanacearum biovar (bv) 2 causes bacterial wilt and potato brown rot in solanaceous plants in temperate areas. The pathogen is able to persist in the environment, where it is frequently disseminated by watercourses. In these habitats, the effect of long-term oligotrophy on its survival remains to be ascertained. On that purpose river water microcosms were inoculated with R. solanacearum bv 2, incubated at 24°C and monitored for total, viable and culturable bacterial cell numbers up to four years. Within the first year, R. solanacearum bv 2 populations remained roughly constant in the initial levels. Then and until the fourth year, total counts slowly increased, while viability slightly declined and culturability decreased to a greater extent, pointing out a proportion of the bacterial populations entering the viable but non-culturable state. As cells in this state are not detected by cultivation-based methods, they represent a new challenge in designing strategies for control of the bacterial wilt disease.

Doxorubicin (DOXO), an anthracycline antibiotic, is a potent anticancer agent with severe toxic side-effects that have been attributed to its ability to generate free radicals (ROS), particularly in mitochondria. In this study, a prokaryotic organism, Salmonella typhimurium, was used to evaluate the effect of the drug on ROS-scavenging enzymes, catalase (CAT) and superoxide dismutase (SOD) activity, and on cell growth and viability. Increasing DOXO concentrations in the culture medium led to increasingly prolonged lag period, reduced growth rate and cell viability, and inhibition of SOD and CAT activity. SOD activity dropped to 66% of the control value in cells grown with 1 µg/ml DOXO and to 34% and 28% in cells grown with 150 and 300 µg/ml DOXO. CAT activity decreased progressively from 93% in 1 µg/ml DOXO to 30% in 150 µg/ml DOXO and was undetectable in 300 µg/ml. Growth in the presence of DOXO led to alterations in cytokinesis, as seen upon examination of cells under fluorescence microscope.

The extended distribution of L. monocytogenes in the environment and its ability to persist in food-processing environments cause the frequent contamination of foods, which represents the main source of human infection. Our objective was to assess the effect of chlorine water treatment on L. monocytogenes and to study this organism's survival strategies in chlorinated water.

RNA content, 16S rRNA (FISH), DNA content (16S rDNA and hlyA gene), culturability and substrate responsiveness combined with FISH detection (DVC-FISH assay) were assessed. L. monocytogenes cell culturability was lost after 2h in drinking water with 0.16 and 1 mg/L of free chlorine. Viability was conserved for more than 16 hours at minor chlorine concentrations. Both, the 16S rDNA gene amplicon and the hlyA fragment, specifics for L. monocytogenes, were detected after a 24-hour chlorine exposure. 16S RNA levels were constant during chlorine treatment, thus chlorine-damage of bacteria is unlikely to involve ribosome degradation. Combinied modified DVC and FISH techniques can rapidly and specifically detect and identify viable L. monocytogenes cells in water samples. Some normal disinfection practices used in drinking water treatment (free chlorine lower than 0.2 mg/L) proved to be inadequate at short time of exposition to control this organism, as it could survive in VBNC state, what can become a public health risk.