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Genetics and exercise: an introduction
Published in Adam P. Sharples, James P. Morton, Henning Wackerhage, Molecular Exercise Physiology, 2022
Claude Bouchard, Henning Wackerhage
Whilst this seems straightforward, in practice the changes in the frequency of DNA variants are often difficult to understand. For example, genome-wide association studies (GWASs) have revealed thousands of common DNA variants that are positively or negatively associated with chronic diseases (30). How could potentially deleterious DNA variants become common variants and why were they not removed from the human gene pool by negative selection? In this case, the explanation probably has to do with the very small effect size of these GWAS common variants. A common variant associated with a chronic disease may also have become prevalent because the variant is simultaneously associated with another trait favouring reproductive fitness. Another example: high cardiorespiratory fitness (31) and high grip strength (32) are both associated with lower mortality. Why then don’t we see strong evidence of positive selection of DNA variants that would result in humans having a VO2max of about 80 ml/min/kg and Herculean strength? Perhaps we need to wait for a few thousand more generations to establish whether there is an ongoing selection trend that currently escapes us.
Introduction to Infection, Resistance, and Immunity
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
All life-forms on planet Earth are constructed from the same materials, and assembled in basically the same way. All compete for the same resources and each is rich in directly utilizable processed materials. Each life-form provides an opportunity for creative exploitation by others, Le., can enhance reproductive fitness of other life forms by being food or shelter, or by making iteasier to obtain food or shelter. In short, life-forms on this planet did not, and do not, get on by ignoring each other.
Peutz−Jeghers Syndrome
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
PJS is inherited in an autosomal dominant pattern, in which one copy of the altered STK11 gene in each cell is sufficient to increase the risk by up to 54% of developing noncancerous polyps and cancerous tumors. While about 55% of PJS patients inherit the mutation from one affected parent, the rest (45%) do not have a family history and appear to acquire de novo mutation in the STK11 gene. The latter may possibly reflect the low reproductive fitness of PJS patients prior to the introduction of effective treatment for intussusception.
Antagonistic pleiotropy: the example of cardiac insulin-like growth factor signaling, which is essential in youth but detrimental in age
Published in Expert Opinion on Therapeutic Targets, 2023
Mahmoud Abdellatif, Frank Madeo, Simon Sedej, Guido Kroemer
Aging is a progressive and multi-faceted degenerative process afflicting virtually every cell and organ system across the human body [1,2]. Hence, age is by far the leading risk factor of morbidity, frailty, disability and death. Various theories and hypotheses have been suggested to explain the complex phenomenon of aging, with the aim to develop anti-aging therapies that might promote health and protect from age-related chronic diseases. The antagonistic pleiotropy theory is amongst the widely accepted theories for the evolutionary origin of aging [3], which argues that genes and molecular pathways that are beneficial for organismal fitness early in life often cause aging and age-related diseases late in life. The reasoning behind this is that modern civilization and its amenities, like unlimited access to nutrient resources as well as medical progress, drove human lifespan beyond evolutionary pressure and, hence, genes were selected without consideration of their consequences during aging. A more refined version of this theoretical framework later suggested that a trade-off exists between reproductive fitness and longevity. This idea, also known as the disposable soma theory [4], proposes that aging might emerge due to steering finite cellular energy resources away from maintenance and repair – which are essential to neutralize internal and external noxious events during the course of life – toward growth and reproduction. (For further details on the evolutionary theories of aging, we refer the readers to more comprehensive reviews on the topic [5,6].)
From tangled banks to toxic bunnies; a reflection on the issues involved in developing an ecosystem approach for environmental radiation protection
Published in International Journal of Radiation Biology, 2022
Carmel E. Mothersill, Deborah H. Oughton, Paul N. Schofield, Michael Abend, Christelle Adam-Guillermin, Kentaro Ariyoshi, Nicholas A. Beresford, Andrea Bonisoli-Alquati, Jason Cohen, Yuri Dubrova, Stanislav A. Geras’kin, Tanya Helena Hevrøy, Kathryn A. Higley, Nele Horemans, Awadhesh N. Jha, Lawrence A. Kapustka, Juliann G. Kiang, Balázs G. Madas, Gibin Powathil, Elena I. Sarapultseva, Colin B. Seymour, Nguyen T. K. Vo, Michael D. Wood
The discussion centered mainly on the types of mechanistic analysis that might help in probing laboratory-field discrepancies, including the influence of neurological, immune and humoral responses and DNA damage. Although there is increasing evidence to suggest that ionizing radiation, like chemicals, can induce a variety of biological responses e.g. in the nervous, immune, endocrine or inflammatory systems (Jha 2004, 2008), these systems are relatively poorly understood in natural biota. Radiation is known to generate oxidative stress in humans, laboratory animals (Hurem et al. 2017; Maremonti et al. 2019) and wild populations (Einor et al. 2016; Volkova et al. 2017), by increasing oxidative damage and decreasing antioxidant defenses. If the key physiological systems mentioned above are impacted by redox imbalances under chronic exposure conditions, they could eventually impair the reproductive fitness of the organisms and the populations in a stressed ecosystem (Jha 2008). For example, sub-lethal effects can impair homeostatic or physiological conditions, and inflammation has been linked to a range of aging-related pathologies.
Genetic variations as molecular diagnostic factors for idiopathic male infertility: current knowledge and future perspectives
Published in Expert Review of Molecular Diagnostics, 2021
Mohammad Karimian, Leila Parvaresh, Mohaddeseh Behjati
It is clear that genetic variations in key genes involved in male reproductive pathways can play an important role in the pathogenesis of infertility. Having the knowledge of being carriers of SNPs associated with male infertility enables physicians for carrier screening and assessment of reproductive risk. This also facilitates recognition of multifactorial genetic-base predisposition to sublethal pathologic conditions, which could impair reproductive fitness. Indeed, enhanced information regarding patient’s reproductive phenotypes at the preconception stage would be helpful in the diagnosis of infertility, the development of future therapeutic tools and also improving the health of future children. Being familiar with the patient’s reproductive genotype and preconception anticipation of genetic defects will be helpful in the work-up of cases with idiopathic infertility by avoidance of repeated failed IVF cycles and related times and costs.