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Evolutionary Biology of Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
The simplified version of the trade-off model in equation 7.1 indicates an optimum virulence is found by maximizing R0, the number of secondary infections produced by a primary infection. R0 is basically a measure of the parasite’s lifetime reproductive success. The essential trade-off referred to in most cases is between how fast and how long the parasite can be transmitted. High rates of progeny production are beneficial, but they would be expected to increase the virulence to the host and possibly cause host mortality, induce strong immunity and limit infection duration or limit the host’s mobility, all potentially limiting the interval that transmission is possible. Conversely, a lower rate of progeny reproduction might extend host longevity, diminish the immune response and enable transmission to persist longer, but fewer offspring are produced per unit time. Depending on the peculiarities of the system in question, any level of virulence could potentially evolve. Note also that the trade-off model refers to a host–parasite system in equilibrium (one that has been established for a long time such that selection on parasite virulence can approach an optimum value). The model presented above emphasizes transmission between hosts, and though it does not address interactions among parasites within hosts, such interactions can clearly influence the nature of between-host transmission.
Selection of Human Hemopoietic Stem Cells
Published in Adrian P. Gee, BONE MARROW PROCESSING and PURGING, 2020
Peter M. Lansdorp, Terry E. Thomas
Blood-forming (hemopoietic) cells represent a continuum of differentiating cells that are often subdivided into three sequential compartments.1 In this model of hemopoiesis the vast majority of cells are in the terminally maturing or differentiation compartment. These cells have limited or no proliferative capacity, and are thought to be in transit towards their final destination as specialized end cells in the peripheral blood. Typically, these cells can be uniquely recognized as belonging to a particular differentiation lineage by their morphology. The immediate precursors of the cells of the differentiation compartment make up the progenitor cell compartment. The cells of this compartment represent only a few percent of all the cells in the hemopoietic tissues. Most are already restricted to differentiate along a single lineage, but may have quite extensive proliferative capacity (yielding 10 to 10,000 mature progeny). The cells of the progenitor cell compartment appear morphologically as blast cells, without specific features indicative of the hemopoietic lineage to which they are committed. Progenitor cells are not, however, a selfsustaining population, and are derived from cells of the stem cell compartment. Stem cells are thus operationally defined by their ability to self-renew as well as to generate daughter cells of any of the hemopoietic lineages.
Fat
Published in Christopher Cumo, Ancestral Diets and Nutrition, 2020
In evoking prehistory, Perlmutter and Taubes apparently sought evolutionary support for high-fat consumption. The word “evolution” is shorthand for species’ adaptation to their environment over time. Since British naturalist Charles Robert Darwin (1809–1882) published On the Origin of Species in 1859, biologists have described adaptation in reproductive terms. Organisms best adapted to their environment are most likely to survive long enough to populate the world with their offspring. Because progeny tend to resemble parents, organisms with advantageous traits often pass these advantages to the next generation. Over time, organisms with such traits dominate an environment, in this way fitting species to it.
The intercellular communications mediating radiation-induced bystander effects and their relevance to environmental, occupational, and therapeutic exposures
Published in International Journal of Radiation Biology, 2023
Manuela Buonanno, Géraldine Gonon, Badri N. Pandey, Edouard I. Azzam
To reiterate, rapid advances in the past three decades in detecting and quantifying biological changes strongly show that when specific cells or tissues are traversed by ionizing radiation, a significant proportion of non-irradiated cells and tissues adjacent to the irradiated zone, or distant from it, experience measurable biological changes that are transient, persistent, or whose expression emerge at later time. Important biological changes may also manifest in their progeny. Hence, bystander and abscopal responses, as well as the expression of genomic instability in progeny of surviving bystander or irradiated cells cannot be considered as non-targeted effects. The cells and tissues that were not themselves irradiated are also targets of the radiation exposure and experience biochemical changes that are often similar to the cells traversed by radiation. Therefore, classification of these responses as non-targeted effects may be inappropriate. Here, it is proposed that these effects be classified as out-of-field effects of ionizing radiation.
Enhanced antioxidant capacity prevents epitranscriptomic and cardiac alterations in adult offspring gestationally-exposed to ENM
Published in Nanotoxicology, 2021
Amina Kunovac, Quincy A. Hathaway, Mark V. Pinti, Andrya J. Durr, Andrew D. Taylor, William T. Goldsmith, Krista L. Garner, Timothy R. Nurkiewicz, John M. Hollander
We hypothesize that altered m6A status of the 3′-UTR of mPHGPx in the hearts of adult offspring contributes to mitochondrial and cardiac functional deficits and that overexpression of mPHGPx (in the mother or pup) can preserves these functional alterations following maternal ENM inhalation exposure. Through the use of differential breeding strategies, we were able to determine that the maternal transgene is protective for the fetus and the benefit is sustained in adult offspring, regardless of whether the progeny also possessed the transgene. Following gestational ENM inhalation exposure, mPHGPx enzymatic activity was entirely preserved only in offspring whose dams were mPHGPx transgenic. M6A methylation was highly enriched in the 3′-UTR of mPHGPx in wild-type (WT) offspring exposed in utero to nano-TiO2, but maternal mPHGPx overexpression prevented this modification. Our findings suggest that enhancing antioxidant defense in the pregnant dam may provide offspring with the most protection from epitranscriptomic remodeling and subsequent long-term cardiovascular repercussions that arise following gestational nano-TiO2 inhalation exposure.
C. elegans aversive olfactory learning generates diverse intergenerational effects
Published in Journal of Neurogenetics, 2020
Ana Goncalves Pereira, Xicotencatl Gracida, Konstantinos Kagias, Yun Zhang
In many organisms, the behaviour and physiology of progeny are modulated by parental experience, ultimately generating traits that often resemble the acquired phenotype of the parents (Bohacek & Mansuy, 2015; Dias, Maddox, Klengel, & Ressler, 2015; Horsthemke, 2018; Miska & Ferguson-Smith, 2016; Weigel & Colot, 2012). A growing body of evidence documents the intergenerational transfer of acquired traits, such as stress response or olfactory sensitivity in rodents (Dias & Ressler, 2014; Gapp et al., 2014). This form of plasticity “anticipates” that the next generation will experience a similar environment to their parents, in which case it may prove to be adaptive. However, the same parental experience can affect progeny differentially depending on their sex, genotype, further ancestral history and life experience (Bohacek & Mansuy, 2015; Deas, Blondel, & Extavour, 2019; Kundakovic et al., 2013; Palominos et al., 2017). These observations suggest that inter- and transgenerational regulations are influenced by many different factors and do not always copy the parentally acquired traits.