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Clostridium perfringens isolates associated with food poisoning carries a chromosomal cpe gene, while non-foodborne human gastrointestinal disease isolates carry a plasmid cpe gene. The enterotoxigenic strains tested produced vegetative cells and spores with significantly higher resistance than non-enterotoxigenic strains. These results suggest that the vegetative cells and spores have a competitive advantage over non-enterotoxigenic strains. However, no explanation has been provided for the significant associations between chromosomal cpe genotypes with the high resistance, which could explain the strong relationship between chromosomal cpe isolates and C. perfringens type A food poisoning. Here, we analyse the action of physical and chemical agent on non-enterotoxigenic and enterotoxigenic regional strains. And this study tested the relationship between the sensitivities of spores and their levels SASPs (small acid soluble proteins) production in the same strains examined. [ABSTRACT FROM AUTHOR]

Zooarchaeologists have relied upon various approaches to study the impacts of harvest pressure and environmental change on ungulate populations, such as analysis of prey mortality patterns and morphometrics. Analysis of ancient DNA from ungulate bones and bone fragments from archaeological sites provides an additional means for studying prey population dynamics related to environmental change and human ecology over time. In this paper, we study the population history of the largest game animal in northwest Patagonia, the guanaco (Lama guanicoe). Our study relies on the use of Bayesian Skyline Plots to determine shifts in estimated guanaco population size based on analysis of ancient mitochondrial DNA. Our results indicate that hunting by humans in addition to increases in aridity during the late Holocene led to a decline in the guanaco population in the region, which is in contrast to the harvest and environmental history in other parts of Patagonia (south of our study area). Using a weight of evidence approach that includes proxies of environmental change, human population dynamics, exploitation of guanacos, and estimates of guanaco population size, we argue that the late Holocene shift in guanaco population size was a driving factor in subsistence and settlement change related to resource intensification during the late Holocene in northwest Patagonia. • Demographic reconstruction of guanaco population dynamics during the Holocene. •Estimated population size is based on ancient DNA analysis through Next Generation Sequencing. •There are key changes in guanaco population size during the late Holocene. •Late Holocene guanaco population relates to increased hunting pressure in northwest Patagonia. [ABSTRACT FROM AUTHOR]