Transmissible cancer and the evolution of sex

The origin and subsequent maintenance of sex and recombination are among the most elusive and controversial problems in evolutionary biology. Here, we propose a novel hypothesis, suggesting that sexual reproduction not only evolved to reduce the negative effects of the accumulation of deleterious mutations and processes associated with pathogen and/or parasite resistance but also to prevent invasion by transmissible selfish neoplastic cheater cells, henceforth referred to as transmissible cancer cells. Sexual reproduction permits systematic change of the multicellular organism\u27s genotype and hence an enhanced detection of transmissible cancer cells by immune system. Given the omnipresence of oncogenic processes in multicellular organisms, together with the fact that transmissible cancer cells can have dramatic effects on their host fitness, our scenario suggests that the benefits of sex and concomitant recombination will be large and permanent, explaining why sexual reproduction is, despite its costs, the dominant mode of reproduction among eukaryotes

Evaluation of the Human IgG Antibody Response to Aedes albopictus Saliva as a New Specific Biomarker of Exposure to Vector Bites

Aedes-borne viruses like dengue and chikungunya are a major problem in Reunion Island. Assessing exposure to Aedes bites is crucial to estimating the risk of pathogen transmission. Currently, the exposure of populations to Aedes albopictus bites is mainly evaluated by entomological methods which are indirect and difficult to apply on a large scale. Recent findings suggest that evaluation of human antibody responses against arthropod salivary proteins could be useful in assessing exposure to mosquito bites. The results indicate that 88% of the studied population produce IgG to Ae. albopictus saliva antigens in Reunion Island and show that this biomarker can detect different levels of individual exposure. In addition, little cross-reactivity is observed with Aedes aegypti saliva, suggesting that this could be a specific marker for exposure to Aedes albopictus bites. Taken together, these results suggest that antibody responses to saliva could constitute a powerful immuno-epidemiological tool for evaluating exposure to Aedes albopictus and therefore the risk of arbovirus infection

Petit guide des architectures en pisé à Lyon

International audienceLa ville de Lyon est classée "Patrimoine de l'humanité", pourtant cette appellation ne recouvre nullement un patrimoine méconnu et très menacé, les constructions en pisé de terre. De fait, l'agglomération lyonnaise est sans doute l'une des rares villes en Europe à concentrer une telle proportion de " pisé urbain ". Ce sont des bâtiments, parfois de grande hauteur, construits au centre comme en périphérie, selon une tradition ancienne jusqu'au début du 20ème siècle. Le fait que l'un des plus importants théoriciens historiques, François Cointereau (1740-1830), soit originaire de cette cité, dans laquelle il a largement expérimenté ses propositions, n'est sans doute pas anodi

Obesity paradox in cancer: is bigger really better?

While obesity is widely recognized as a risk factor for cancer, survival among patients with cancer is often higher for obese than for lean individuals. Several hypotheses have been proposed to explain this "obesity paradox," but no consensus has yet emerged. Here, we propose a novel hypothesis to add to this emerging debate which suggests that lean healthy persons present conditions unfavorable to malignant transformation, due to powerful natural defenses, whereby only rare but aggressive neoplasms can emerge and develop. In contrast, obese persons present more favorable conditions for malignant transformation, because of several weight-associated factors and less efficient natural defenses, leading to a larger quantity of neoplasms comprising both nonaggressive and aggressive ones to regularly emerge and progress. If our hypothesis is correct, testing would require the consideration of the raw quantity, not the relative frequency, of aggressive cancers in obese patients compared with lean ones. We also discuss the possibility that in obese persons, nonaggressive malignancies may prevent the subsequent progression of aggressive cancers through negative competitive interactions between tumors

Cancer brings forward oviposition in the fly Drosophila melanogaster

Abstract Hosts often accelerate their reproductive effort in response to a parasitic infection, especially when their chances of future reproduction decrease with time from the onset of the infection. Because malignancies usually reduce survival, and hence potentially the fitness, it is expected that hosts with early cancer could have evolved to adjust their life-history traits to maximize their immediate reproductive effort. Despite the potential importance of these plastic responses, little attention has been devoted to explore how cancers influence animal reproduction. Here, we use an experimental setup, a colony of genetically modified flies Drosophila melanogaster which develop colorectal cancer in the anterior gut, to show the role of cancer in altering life-history traits. Specifically, we tested whether females adapt their reproductive strategy in response to harboring cancer. We found that flies with cancer reached the peak period of oviposition significantly earlier (i.e., 2 days) than healthy ones, while no difference in the length and extent of the fecundity peak was observed between the two groups of flies. Such compensatory responses to overcome the fitness-limiting effect of cancer could explain the persistence of inherited cancer-causing mutant alleles in the wild. K E Y W O R D S cancer, fecundity, life-history strategy, reproductio

Rare and unique adaptations to cancer in domesticated species: An untapped resource?

Strong and ongoing artificial selection in domestic animals has resulted in amazing phenotypic responses that benefit humans, but often at a cost to an animal's health, and problems related to inbreeding depression, including a higher incidence of cancer. Despite high rates of cancer in domesticated species, little attention has been devoted to exploring the hypothesis that persistent artificial selection may also favour the evolution of compensatory anticancer defences. Indeed, there is evidence for effective anti-cancer defences found in several domesticated species associated with different cancer types. We also suggest that artificial selection can favour the "domestication" of inherited oncogenic mutations in rare instances, retaining those associated to late and/or less aggressive cancers, and that by studying these seemingly rare anticancer adaptations, novel cancer treatments may be found

Individual IgG response to <i>Ae. albopictus</i> or <i>Ae. aegypti</i> SGE in Reunion Island and Bolivia.

<p>Individual IgG responses against <i>Ae. albopictus</i> SGE and <i>Ae. aegypti</i> SGE are presented in individuals from Reunion Island (black circle) and from Bolivia (white circle). The percentage of positive responders is indicated for each group. Bars indicate median value in each group. The dotted and solid lines represent the threshold of specific Ab response to <i>Ae. albopictus</i> (ΔOD = 0.271) and <i>Ae. aegypti</i> SGE (ΔOD = 0.161), respectively.</p

Individual IgG response to <i>Ae. albopictus</i> SGE in Reunion Island.

<p>Exposed (n = 110, Reunion Island) and unexposed individuals (n = 18, North France). Individual IgG Ab responses are represented by ΔOD. Bars indicate median value in each group and the dotted line represents the threshold of specific Ab response to <i>Ae. Albopictus</i> SGE (ΔOD = 0.271).</p

Individual cross-reactivity IgG response between <i>Ae. albopictus</i> and <i>Ae. aegypti</i> SGE.

<p>Correlations between IgG against <i>Ae. albopictus</i> SGE and <i>Ae. aegypti</i> SGE in Reunion Island (black circle) and Bolivia (white circle). The coefficient of correlation (r) and significance are indicated for each species SGE, black lines represent linear Spearman correlation.</p

Natural resistance to cancers: a Darwinian hypothesis to explain Peto’s paradox

<p>Abstract</p> <p>Background</p> <p>Peto's paradox stipulates that there is no association between body mass (a surrogate of number of cells and longevity) and cancer prevalence in wildlife species. Resolving this paradox is a very promising research direction to understand mechanisms of cancer resistance. As of present, research has been focused on the consequences of these evolutionary pressures rather than of their causes.</p> <p>Discussion</p> <p>Here, we argue that evolution through natural selection may have shaped mechanisms of cancer resistance in wildlife species and that this can result in a threshold in body mass above which oncogenic and tumor suppressive mechanisms should be increasingly purified and positively selected, respectively.</p> <p>Summary</p> <p>We conclude that assessing wildlife species in their natural ecosystems, especially through theoretical modeling, is the most promising way to understand how evolutionary processes can favor one or the other pathway. This will provide important insights into mechanisms of cancer resistance.</p