Replication Checkpoint Protein Mrc1 Is Regulated by Rad3 and Tel1 in Fission Yeast

Fission yeast Mrc1 (mediator of replication checkpoint 1) is an adaptor checkpoint protein required for Rad3-dependent activation of the checkpoint kinase Cds1 in response to arrest of replication forks. Here we report studies on the regulation of Mrc1 by phosphorylation. Replication arrest induced by hydroxyurea (HU) induces Mrc1 phosphorylation that is detected by a change in Mrc1 electrophoretic mobility. Phosphorylation is maintained in cds1Δ, rad3Δ, and tel1Δ single mutants but eliminated in a rad3Δ tel1Δ double mutant. Mrc1 has two clusters of S/TQ motifs that are potential Rad3/Tel1 phosphorylation sites. Mutation of six S/TQ motifs in these two clusters strongly impairs Mrc1 phosphorylation. Two motifs located at S604 and T645 are vital for HU resistance. The T645A mutation strongly impairs a Cds1-Mrc1 yeast two-hybrid interaction that is dependent on a functional forkhead-associated (FHA) domain in Cds1, indicating that phosphorylation of T645 mediates Mrc1's association with Cds1. Consistent with this model, the T645 region of Mrc1 effectively substitutes for the T11 region of Cds1 that is thought to be phosphorylated by Rad3 and to mediate FHA-dependent oligomerization of Cds1. The S/TQ cluster that includes S604 is needed for Mrc1's increased association with chromatin in replication-arrested cells. These data indicate that Rad3 and Tel1 regulate Mrc1 through differential phosphorylation to control Cds1

Antioxidant, genotoxic and antigenotoxic activities of daphne gnidium leaf extracts

<p>Abstract</p> <p>Background</p> <p>Plants play a significant role in maintaining human health and improving the quality of human life. They serve humans well as valuable components of food, as well as in cosmetics, dyes, and medicines. In fact, many plant extracts prepared from plants have been shown to exert biological activity <it>in vitro</it> and <it>in vivo</it>. The present study explored antioxidant and antigenotoxic effects of <it>Daphne gnidium</it> leaf extracts.</p> <p>Methods</p> <p>The genotoxic potential of petroleum ether, chloroform, ethyl acetate, methanol and total oligomer flavonoid (TOF) enriched extracts from leaves of <it>Daphne gnidium</it>, was assessed using <it>Escherichia coli</it> PQ37. Likewise, the antigenotoxicity of the same extracts was tested using the “SOS chromotest test”. Antioxidant activities were studied using non enzymatic and enzymatic method: NBT/Riboflavine and xantine oxidase.</p> <p>Results</p> <p>None of the different extracts produced a genotoxic effect, except TOF extract at the lowest tested dose. Our results showed that <it>D. gnidium</it> leaf extracts possess an antigenotoxic effect against the nitrofurantoin a mutagen of reference. Ethyl acetate and TOF extracts were the most effective in inhibiting xanthine oxidase activity. While, methanol extract was the most potent superoxide scavenger when tested with the NBT/Riboflavine assay.</p> <p>Conclusions</p> <p>The present study has demonstrated that <it>D. gnidium</it> leaf extract possess antioxidant and antigenotoxic effects. These activities could be ascribed to compounds like polyphenols and flavonoid. Further studies are required to isolate the active molecules.</p

The health impact of tourism on local and Indigenous populations in resource-poor countries

In the vast Travel Health literature there is still a considerable dearth on tourism’s impact on local communities. This review attempts to remedy the situation. Its focus is on potential health impacts on populations living at tourist destinations outside the industrialised world. To facilitate a better understanding of how health is linked to tourism today, a brief overview of the historical and theoretical evolution of tourism is presented. Ecotourism is given special attention as it is perceived as a version of the industry that is more benign on environment and people. After discussing Indigenous Tourism, a variety of potential health implications is outlined. These follow a previously suggested classification of indirect and direct impacts, with the indirect impacts being based on economic, environmental, socio-cultural and, more recently, political impacts, and the direct impacts originating from immediate encounters between tourism and people. Finally, the urgent need for more research is highlighted, and some solutions to minimize health impact are suggested