The adaptation of rainbow trout to warmer water: oxidative damage in the germinal line

Contemporary evolution was observed in a feral rainbow trout (Oncorhynchus mykiss) population of a thermal stream (Valcheta) in Northern Patagonia, in terms of juvenile thermal tolerance and preferred temperature. Other authors showed that high-temperature treatment applied to male rainbow trout juveniles increased the thermal tolerance in the next generation. This implies a high mutation rate and/or a modified epigenetic inheritance. Comparisons were made among a) a rainbow trout strain adapted in terms of upper thermal tolerance and higher preferred temperature (Valcheta stream), b) a wild temperate stream population (Guillelmo stream), and c) two temperate farmed strains. We examined: Oxidative damage (lipid peroxidation) and activities of antioxidant enzymes; Catalase (CAT), Glutathione S-Transferases (GST), and Superoxide Dismutase (SOD), in liver, testicle, and spermatozoa. Semen fatty acid composition, sperm morphology, sperm motility, and fertilization performance in samples before and after the application of cryopreservation procedures were also evaluated. The observed responses, mainly related to the sperm membrane, reinforces the idea that ROS can affect the germinal line of male rainbow trout juveniles subjected to high water temperature. Our results suggest that the acquired thermal tolerance traits may be part of a wide spectrum of novel characteristics produced as a consequence of an enhanced mutation rate and/or a different DNA methylation pattern, induced by higher temperatures and mediated by ROS.Centro de Investigación y Desarrollo en Criotecnología de Alimento

The adaptation of rainbow trout to warmer water: oxidative damage in the germinal line

Contemporary evolution was observed in a feral rainbow trout (Oncorhynchus mykiss) population of a thermal stream (Valcheta) in Northern Patagonia, in terms of juvenile thermal tolerance and preferred temperature. Other authors showed that high-temperature treatment applied to male rainbow trout juveniles increased the thermal tolerance in the next generation. This implies a high mutation rate and/or a modified epigenetic inheritance. Comparisons were made among a) a rainbow trout strain adapted in terms of upper thermal tolerance and higher preferred temperature (Valcheta stream), b) a wild temperate stream population (Guillelmo stream), and c) two temperate farmed strains. We examined: Oxidative damage (lipid peroxidation) and activities of antioxidant enzymes; Catalase (CAT), Glutathione S-Transferases (GST), and Superoxide Dismutase (SOD), in liver, testicle, and spermatozoa. Semen fatty acid composition, sperm morphology, sperm motility, and fertilization performance in samples before and after the application of cryopreservation procedures were also evaluated. The observed responses, mainly related to the sperm membrane, reinforces the idea that ROS can affect the germinal line of male rainbow trout juveniles subjected to high water temperature. Our results suggest that the acquired thermal tolerance traits may be part of a wide spectrum of novel characteristics produced as a consequence of an enhanced mutation rate and/or a different DNA methylation pattern, induced by higher temperatures and mediated by ROS.Centro de Investigación y Desarrollo en Criotecnología de Alimento

The Trypanosoma cruzi vitamin C dependent peroxidase confers protection against oxidative stress but is not a determinant of virulence.

BACKGROUND: The neglected parasitic infection Chagas disease is rapidly becoming a globalised public health issue due to migration. There are only two anti-parasitic drugs available to treat this disease, benznidazole and nifurtimox. Thus it is important to identify and validate new drug targets in Trypanosoma cruzi, the causative agent. T. cruzi expresses an ER-localised ascorbate-dependent peroxidase (TcAPx). This parasite-specific enzyme has attracted interest from the perspective of targeted chemotherapy. METHODOLOGY/PRINCIPAL FINDINGS: To assess the importance of TcAPx in protecting T. cruzi from oxidative stress and to determine if it is essential for virulence, we generated null mutants by targeted gene disruption. Loss of activity was associated with increased sensitivity to exogenous hydrogen peroxide, but had no effect on susceptibility to the front-line Chagas disease drug benznidazole. This suggests that increased oxidative stress in the ER does not play a significant role in its mechanism of action. Homozygous knockouts could proceed through the entire life-cycle in vitro, although they exhibited a significant decrease in their ability to infect mammalian cells. To investigate virulence, we exploited a highly sensitive bioluminescence imaging system which allows parasites to be monitored in real-time in the chronic stage of murine infections. This showed that depletion of enzyme activity had no effect on T. cruzi replication, dissemination or tissue tropism in vivo. CONCLUSIONS/SIGNIFICANCE: TcAPx is not essential for parasite viability within the mammalian host, does not have a significant role in establishment or maintenance of chronic infections, and should therefore not be considered a priority for drug design

Drug Resistance in Eukaryotic Microorganisms

Eukaryotic microbial pathogens are major contributors to illness and death globally. Although much of their impact can be controlled by drug therapy as with prokaryotic microorganisms, the emergence of drug resistance has threatened these treatment efforts. Here, we discuss the challenges posed by eukaryotic microbial pathogens and how these are similar to, or differ from, the challenges of prokaryotic antibiotic resistance. The therapies used for several major eukaryotic microorganisms are then detailed, and the mechanisms that they have evolved to overcome these therapies are described. The rapid emergence of resistance and the restricted pipeline of new drug therapies pose considerable risks to global health and are particularly acute in the developing world. Nonetheless, we detail how the integration of new technology, biological understanding, epidemiology and evolutionary analysis can help sustain existing therapies, anticipate the emergence of resistance or optimize the deployment of new therapies

Guiding principles for the development and application of solid-phase phosphorus adsorbents for freshwater ecosystems

While a diverse array of phosphorus (P)-adsorbent materials is currently available for application to freshwater aquatic systems, selection of the most appropriate P-adsorbents remains problematic. In particular, there has to be a close correspondence between attributes of the P-adsorbent, its field performance, and the management goals for treatment. These management goals may vary from a rapid reduction in dissolved P to address seasonal enrichments from internal loading, targeting external fluxes due to anthropogenic sources, or long term inactivation of internal P inventories contained within bottom sediments. It also remains a challenge to develop new methods and materials that are ecologically benign and cost-effective. We draw on evidence in the literature and the authors’ personal experiences in the field, to summarise the attributes of a range of P-adsorbent materials. We offer 'guiding principles' to support practical use of existing materials and outline key development needs for new materials

Acanthostomoides apophalliformis (Trematoda: Cryptogonimidae) does not cause detectable mortality in Galaxias maculatus (Teleostomi: Galaxiidae)

The present study was conducted to determine if parasite induced mortality existed in a "puyen" population in Moreno Lake, southern Argentina. Data on both parasite abundance and degree of aggregation of parasite frequency distribution showed the absence of fish mortality induced by A. apophalliformis.<br>Acanthostomoides apophalliformis (Trematoda: Cryptogonimidae) não causa mortalidade detectável no peixe Galaxias maculatus (Teleostomi: Galaxiidae) de Argentina do Sul. O "puyen", Galaxias maculatus, é um peixe nativo pequeno que habita a América do Sul e a Oceania. Acanthostomoides apophalliformis é um trematódeo digenético que parasita, freqüentemente, os "puyenes". O estudo atual foi conduzido para determinar se existe mortalidade induzida por parasito no população do "puyen" no lago Moreno, no sul de Argentina. Os dados de abundância do parasito e no grau de aggregação da distribuição de freqüência do parasito, sugerem a ausência de mortalidade induzida por A. apophalliformis em "puyenes"

Improving our superannuation regime : a post-Henry review look at superannuation taxation, raising superannuation balances and longevity insurance

This paper examines what, if any changes should be made regarding certain aspects of the superannuation system. Specifically, it looks at possible changes to the superannuation tax regime, measures intended at increasing superannuation balances, as well as policies aimed at improving the price and availability of retirement income streams. The recommendations of the final report of the Henry Review on these issues are also critically evaluated. The paper finds that a greater targeting of superannuation tax concessions towards middle and lower income earners would make the system more equitable and achieve other desirable goals such as increasing voluntary savings. Furthermore, the available evidence suggests that the current mandatory contributions rate of 9% is adequate, and a higher contributions rate is likely to have more costs than benefits. On the issue of superannuation income streams, the article finds that whilst taxpayers should continue to be allowed to take their superannuation as a lump sum, policies should be implemented to make lifetime annuities more readily available and better value for money. The Henry Review\u27s recommendations on these issues, with some exceptions, are for the most part sound and based on logic.<br /