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Human physiology, hazards and health risks
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2023
Revati Phalkey, Naima Bradley, Alec Dobney, Virginia Murray, John O’Hagan, Mutahir Ahmad, Darren Addison, Tracy Gooding, Timothy W Gant, Emma L Marczylo, Caryn L Cox
At this juncture it is important to add a note that the Dutch hunger winter as cited, with effects in the first generation as a result of in utero exposure, represents multigenerational and not transgenerational inheritance. What is the difference? In the case of the Dutch hunger winter the unborn child was exposed to the calorific deficiency directly. Therefore, the effect was not transmitted through the gametes of either the mother or the father; it was the result of a direct effect on the embryo (albeit via the placenta, but still a direct exposure). It is therefore multigenerational in that there was an effect on the mother in terms of lost weight and on her child as a change in later life health. For transgenerational inheritance there must be transmission of the genotype in the gametes with no direct exposure of the affected offspring. In this situation, the exposure leads to an epigenetic change that results in a phenotype that can be passed through subsequent generations. Furthermore, it is important to distinguish the differences between in utero and adult exposures. During an in utero exposure, the mother (F0 generation), the child (F1 generation) and the gametes that go on to produce the grandchildren (F2 generation) are directly exposed. This means that the effect can only be defined as true transgenerational epigenetic inheritance if the phenotype is found in the great-grandchildren (F3 generation). The great-grandchildren are the first generation to be derived from gametes that have never been exposed. If the exposure occurs in adulthood, then only the F0 generation and the gametes that go onto produce the F1 generation are directly exposed. Here, a phenotype in the grandchildren (F2 generation) would demonstrate transgenerational epigenetic inheritance. For the purposes of the following text, where multi- and transgenerational mechanisms are relevant to health, the term intergenerational will be used to encompass both. (See Figure 10.19.)
Transgenerational male reproductive effect of prenatal arsenic exposure: abnormal spermatogenesis with Igf2/H19 epigenetic alteration in CD1 mouse
Published in International Journal of Environmental Health Research, 2022
Guoying Yin, Liting Xia, Yaxing Hou, Yaoyan Li, Deqing Cao, Yanan Liu, Jingshan Chen, Juan Liu, Liwen Zhang, Qiaoyun Yang, Qiang Zhang, Naijun Tang
Transgenerational epigenetic inheritance is defined as germline-mediated transmission of environmentally induced phenotypes between generations in the absence of direct environmental exposure. When a gestating female (F0 generation) is exposed to an environmental compound, the F1 generation embryo and F2 generation germline were directly exposed to the environmental compound, whereas the F3 generation was the first generation not directly exposed (Heard and Martienssen 2014; Martos et al. 2015). Recent studies have shown that exposure to endocrine-disrupting chemicals can alter epigenetic marks in the germline and induce male reproductive toxicity of multiple generations (Skinner 2016). More recently, it has been reported that maternal arsenite exposure may induce transgenerational reproductive toxicity in Caenorhabditis elegans by demethylation of histone H3K4 (Yu and Liao 2016). However, the transgenerational male reproductive effect of prenatal arsenic exposure remains to be studied in mammals.
Posthumanism: Creation of ‘New Men’ Through Technological Innovation
Published in The New Bioethics, 2021
The expression and activity of genes depends not only the genetic code in the genome, but also on the microstructure (not the code) of the DNA itself and the proteins associated with its packaging in the chromosome; the chemical state of this microstructure and associated proteins constitutes the epigenome. Epigenetics is ‘the study of the mechanisms of temporal and spatial control of gene activity during the development of complex organisms’ (Holliday 1990, 329). Changes in the epigenome can be passed on the offspring via transgenerational epigenetic inheritance (Bernstein et al. 2007). Epigenetic changes wrought by one’s diet, behaviour, or surroundings can work their way into the germ line and echo far into the future (Morgan and Whitelaw 2008). Thus, changes in the phenotype include mechanisms that do not involve alterations of the DNA sequence; consequently, traits depend both on the genome and the epigenome, and modifications of the former alone may not result in the desired traits.