Enhancement of heat sensitivity and modification of repair of potentially lethal heat damage in plateau-phase cultures of mammalian cells by diethyldithiocarbamate

Diethyldithiocarbamate (DDC) is active both in vivo and in vitro in reducing the levels of enzymes such as superoxide dismutase (SOD) and glutathione peroxidase whose role in respiring cells is to remove toxic superoxide radicals and organic hydroperoxides. Although DDC, a copper-chelating agent, has been used to treat benign diseases, its potential as a heat sensitizer has not been fully explored. We have recently shown that the presence of 10(-3) M DDC for 2 hr causes a threefold reduction in the level of SOD in plateau-phase cultures of mammalian cells. At this concentration, the drug causes minimal toxicity but markedly affects both the shoulder and the slope of the heat survival curves. To explore another pathway of DDC sensitization, other than through reduced levels of SOD, we examined the repair of potentially lethal damage with and without DDC following exposure for 1 hr and 40 min at 43 degrees C. The repair, which progressed with a T 1/2 of about 10 hr, in either full medium or Hank's balanced salt solution (HBSS), in the absence of DDC, was completely blocked when DDC was added to the monolayers on completion of the heat exposure. DDC, in view of its ability to potentiate the effects of heat, is a potentially useful drug that could be used in an adjunctive setting with clinical hyperthermia.     

The role of peroxisomes in xylose alcoholic fermentation in the engineered Saccharomyces cerevisiae

Xylose is a second‐most abounded sugar after glucose in lignocellulosic hydrolysates and should be efficiently fermented for economically viable second‐generation ethanol production. Despite significant progress in metabolic and evolutionary engineering, xylose fermentation rate of recombinant Saccharomyces cerevisiae remains lower than that for glucose. Our recent study demonstrated that peroxisome‐deficient cells of yeast Ogataea polymorpha showed a decrease in ethanol production from xylose. In this work, we have studied the role of peroxisomes in xylose alcoholic fermentation in the engineered xylose‐utilizing strain of S. cerevisiae. It was shown that peroxisome‐less pex3Δ mutant possessed 1.5‐fold decrease of ethanol production from xylose. We hypothesized that peroxisomal catalase Cta1 may have importance for hydrogen peroxide, the important component of reactive oxygen species, detoxification during xylose alcoholic fermentation. It was clearly shown that CTA1 deletion impaired ethanol production from xylose. It was found that enhancing the peroxisome population by modulation the peroxisomal biogenesis by overexpression of PEX34 activates xylose alcoholic fermentation.     

Large Differences in Livelihood Responses and Outcomes to Increased Conservation Enforcement in a Protected Area

Human Ecology - Despite the popularity of integrated conservation and development approaches to protected area management, adjacent communities increasingly face livelihood dilemmas. Yet...     

Detecting rare terrestrial orchids and associated plant communities from soil samples with eDNA methods

Biodiversity and Conservation - The complex biology and specialized relationships between orchids and both fungi and pollinators can complicate orchid conservation and management. Some terrestrial...     

An assessment of the seascape genetic structure and hydrodynamic connectivity for subtropical seagrass restoration

Seagrass ecosystems have suffered significant declines globally and focus is shifting to restoration efforts. A key component to successful restoration is an understanding of the genetic factors potentially influencing restoration success. This includes understanding levels of connectivity between restoration locations and neighboring seagrass populations that promote natural recovery (source and sink populations), the identification of potential donor populations, and assessment of genetic diversity of restored meadows and material used for restoration. In this study, we carry out genetic surveys of 352 individuals from 13 populations using 11 polymorphic microsatellite loci to inform seagrass restoration activities by: (1) understanding levels of genetic and genotypic diversity within meadows; and (2) understanding genetic structure and patterns of connectivity among these meadows to determine which source sites may be most appropriate to assist recovery of three restoration sites. The study identified high genotypic diversity within the locations analyzed from the Port of Gladstone and Rodd's Bay region, indicating sexual reproduction is important in maintaining populations. Overall, we detected significant genetic structuring among sites with the Bayesian structure analysis identifying genetic clusters that largely conformed to a northern, central, and southern region. This suggests limited gene flow between regions, although there does appear to be some connectivity within regions. The hydrodynamic models showed that seeds were largely locally retained, while fragments were more widely dispersed. Limited gene flow between regions suggests donor material for restoration should be sourced locally where possible.