DELAYED URIC ACID ACCUMULATION IN PLASMA PROVIDES ADDITIONAL ANTI-OXIDANT PROTECTION AGAINST IRON-TRIGGERED OXIDATIVE STRESS AFTER A WINGATE TEST

Reactive oxygen species are produced during anaerobic exercise mostly by Fe ions released into plasma and endothelial/muscle xanthine oxidase activation that generates uric acid (UA) as the endpoint metabolite. Paradoxically, UA is considered a major antioxidant by virtue of being able to chelate pro-oxidative iron ions. This work aimed to evaluate the relationship between UA and plasma markers of oxidative stress following the exhaustive Wingate test. Plasma samples of 17 male undergraduate students were collected before, 5 and 60 min after maximal anaerobic effort for the measurement of total iron, haem iron, UA, ferric-reducing antioxidant activity in plasma (FRAP), and malondialdehyde (MDA, biomarker of lipoperoxidation). Iron and FRAP showed similar kinetics in plasma, demonstrating an adequate pro-/antioxidant balance immediately after exercise and during the recovery period (5–60 min). Slight variations of haem iron concentrations did not support a relevant contribution of rhabdomyolysis or haemolysis for iron overload following exercise. UA concentration did not vary immediately after exercise but rather increased 29% during the recovery period. Unaltered MDA levels were concomitantly measured. We propose that delayed UA accumulation in plasma is an auxiliary antioxidant response to post-exercise (iron-mediated) oxidative stress, and the high correlation between total UA and FRAP in plasma (R-Square = 0.636; p = 0.00582) supports this hypothesis.     

The attitudes of riparian communities to the presence of water hyacinth in the Wouri River Basin,Douala, Cameroon

Since publication of the first record of Eichhornia crassipes in Cameroon in 1997, the weed has become highly invasive in the Wouri River Basin. Between June and September 2014, a socio-economic survey using participatory and qualitative methods was undertaken in the riparian villages of the Wouri River Basin to assess the perception of respondents to the presence of water hyacinth. The survey revealed that water hyacinth was a significant threat to activities along the river, which included fishing, sand extraction and river transportation. The presence of water hyacinth mats reduced catch rates of several common fish species, river transportation by 75%, and significantly reduced the income for sand extraction. Cameroon employs manual clearing of water hyacinth; however, respondents indicated they would consider other control methods, provided they do not have any negative impacts.     

Chromosome age and segregation during sporulation of Bacillus megaterium.

The effect of chromosome age on segregation during sporulation was investigated. Vegetative cells of Bacillus megaterium were labeled with [Me-3H]thymine and then were grown at 30 degrees C in nonradioactive medium for various times before being allowed to sporulate. The ratio of the amount of label in sporal DNA to that in sporangial DNA, obtained after minor correction for the sporulation frequency, remained essentially constant as the postlabeling growth period was increased from one to seven generations. The spores were preferentially located at the older poles of sporangia, i.e. the poles formed by divisions occurring prior to those forming the sporangia. Therefore, it seems that old (labeled) chromosomes segregate randomly with respect to both the morphological and genealogical polarities of sporangia. Examination of total cell lysates by dye-buoyant density gradient centrifugation revealed the presence of covalently closed circular DNA from cells grown at 37 degrees C, but none was obtained from cells grown at 30 degrees C. Thus, possible interference by large amounts of extrachromosomal DNA in the determination of the chromosomal segregation pattern is unlikely.     

Host cell reactivation by excision repair is error-free in human cells

Do host cell repair processes affect the mutagenesis of UV-irradiated virus in human cells? The answer was obtained by investigating the mutagenesis of UV-irradiated herpes simplex virus after the irradiated virus was grown in human cells that possess normal repair capacity (normal) or lack excision repair (XPA) or post-replication repair (XP var). Evidence is presented which indicate that XPA cells express no host cell reactivation, while XP var cells express the normal level. Viral mutagenesis was measured as the fraction of the progeny of the surviving virus capable of plaque formation in the presence of iododeoxycytidine. In the normal and XPA cells mutagenesis of the irradiated virus increased linearly with UV exposure. The UV exposure needed to yield a given mutagenesis level for virus grown in XPA cells was much lower than that for virus grown in normal cells. However, when the mutation frequencies were compared at similar virus survival levels, the data from virus grown in normal cells and in XPA cells were indistinguishable. Mutagenesis in XP var cells increased as dose squared and was similar in magnitude to that in normal cells. Thus the excision repair of normal cells which provided host cell reactivation by removing lethal UV damage also removed mutagenic lesions from the virus with the same efficiency, while the repair deficiency of XP var cells had a minor role in host cell reactivation and in mutagenesis. This demonstrates that in human cells host cell reactivation by excision repair is primarily an error-free process.