In light of the current opioid epidemic, the past 20 years have made it clear that parental life experiences can significantly impact the behavior and neurobiology of their offspring. Preclinical studies indicate that addiction reflects the interaction of an individual’s environment, genetics, and epigenetic modifications they inherit from their parents. Epigenetic mechanisms - including DNA methylation, histone modification, and small non-coding RNAs – refer to the complex interaction between genes and the environment, which produce heritable changes in germ cells that are transmitted to offspring to ultimately influence the brain development and subsequent vulnerability to develop a substance use disorder. The overarching goal of this dissertation was to characterize the behavioral and neurobiological effects of paternal morphine exposure on addiction-related endpoints in offspring. A highly translational rodent model of paternal morphine self-administration was used to produce first-generation (F1) male and female adolescent and adult offspring. As a reference, offspring derived from morphine-exposed fathers were called morphine-sired offspring, and offspring from saline-exposed fathers were called saline-sired offspring. In chapter 2, we revealed that male morphine-sired progeny are more sensitive over time to the pain-relieving effects of morphine. In the periaqueductal grey, an important pain-related brain region, we identified gene expression changes in regulators of G-protein signaling proteins that could partly account for this phenotype. In chapter 3, we demonstrated that adult morphine-sired male offspring self-administered more morphine; were more motived to earn morphine infusions compared to controls; and had more baseline mu-opioid receptor binding in the ventral tegmental area. Next, in chapter 4, we found that a drug-abstinence period of 90 consecutive days following 60 days of morphine exposure in sires was sufficient to prevent morphine-sired males from self-administering more morphine than controls. In chapter 5, we showed that this addiction-like phenotype did not extend to adolescent male or female offspring. Lastly, in chapter 6, using the incubation of craving paradigm, we found that paternal morphine exposure significantly reduced cue-induced active lever pressing for heroin in morphine-sired males. Taken together, these results add to the growing body of literature that show paternal preconception experiences can impact behavioral and neurobiological endpoints in offspring, perhaps via a(n) epigenetically inherited mechanism(s) in the germline. / Psychology

Western studies have established that men from African descent are disproportionally affected by prostate cancer (PCa). Annual incidence rates in this population vary from 1.5 to 2 times when compared to their counterparts from other racial groups. They also record the worse outcomes in terms of prognosis. Additionally, with the rise of PCa in Subsaharan Africa, new cancer control policies and programs are increasingly demanded. Understanding therefore, factors that underpin racial inequality in distribution and especially why the disease preferentially niches in African males can help better address PCa in both Western and Subsaharan countries. There is also the potential to develop new therapeutic options. A genetic susceptibility was first hypothesized, however available data suggest that they only account for less than 20% of the cases. Current findings from epidemiological and molecular investigations suggest an important role of complex and dynamic environmental interactions involving the different levels of calcium regulation. Using a multi-method design, this research aims at developing an integrative mechanistic model of PCa. We argue that given the versatile and ubiquitous role calcium plays in nutrition, physical environment, and in key cellular processes, that mineral cation is central to prostate tumorigenesis and in shaping its populational distribution. Thus a tree-level investigation was conducted: (i) a critical analysis and synthesis of empirical evidence on calcium interactions with cancer mechanisms (ii) a population-wide prospective cohort study of calcium intake patterns in a group of Subsaharan males in Côte d’Ivoire, namely the African Prostate Cancer Study (APCS) (iii) a proteomics research investigating the responses of prostate cancer cell lines when exposed to a high affinity synthetic calcium binding peptide. This monograph describes the research methods, instruments design and validation and the preliminary findings of the ongoing research, portions of which have already been published, presented at two international cancer seminars or under review. Findings at this stage include: mechanistic models of prostate cancer differential distribution and outcomes, a novel calcium questionnaire specific to African diet, synthesis of a high affinity calcium-binding peptide (Peptide#1). New concepts and constructs related to prostatic carcinogenesis have been developed as well.

Transgenerational epigenetic inheritance in mamals is a widely discussed topic in today's biology. Epigenetic modifications are molecules that play a crucial role in regulation of gene transcription. Epigenetic modifications regulate another epigenetic modification's establishment. The extrinsic and the intrinsic cellular or organismal environment is involved within the establishment of epigenetic state. The molecules involved in epigenetic processes are able to regulate gene transcription in reaction to the environment and therefore these molecules partly shape the phenotype. Most importantly, epigenetic processes are affected by cellular or organismal history. A question emerges: Are these molecules able to transfer information through germline to subsequent generations? Does transgenerational epigenetic inheritance in mammals exist? Experimental data show it is so. What consequences this can mean in our understanding of evolution? Powered by TCPDF (www.tcpdf.org)

Comme tous les ciliés, P. tetraurelia réarrange son génome à chaque génération sexuelle pendant le développement de son macronoyau somatique ¿ partir du micronoyau germinal. Les réarrangements incluent l’excision précise de courtes séquences dérivant de transposons et appelés IES (Internal Eliminated Sequences) dont la majorité sont intragéniques. L’excision d’une fraction d’entre elles dépend de petits ARN maternels (appelés scnARN) qui sont produits à partir de tout le génome germinal pendant la méiose. Ce mécanisme pose un problème lors d’une conjugaison entre deux souches présentant des polymorphismes d’insertion : une cellule sera théoriquement incapable d’exciser une IES portée par l’allèle paternel reçu si cette IES est absente de l’allèle maternel ou si la séquence est trop divergente. Mes résultats montrent cependant que les allèles paternels divergents sont correctement excisés en utilisant les scnARN produit par la cellule paternelle. Dans le cas d’un polymorphisme absence/présence, l’IES que j’ai étudié est excisée chez 70 % des hétérozygotes F1, également via les scnARN paternels. Nous avons exploré deux hypothèses pour expliquer comment ils pouvaient agir. Il pourrait s’agir d’une programmation précoce des noyaux gamétiques ou alors d’un échange cytoplasmique des scnARN. Finalement, j’ai montré qu’un défaut de scnARN maternels n’est pas une cause possible de dysgénésie hybride. Cependant, 30 % des hétérozygotes F1 présentent une rétention variable de l’IES étudié via un mécanisme inconnu. Si cela est généralisable à toutes les IES homozygotes, alors ce mécanisme aurait un effet délétère sérieux sur les F1 et pourrait contribuer à l’isolement reproductif. / Like all ciliates, P. tetraurelia entirely rearranges its genome during development of the somatic macronucleus from the germline micronucleus, in each sexual generation. Rearrangements include the precise excision of IESs (Internal Eliminated Sequences), single-copy intervening sequences likely derived from transposon insertions. At least for a fraction of IESs, correct excision, which is required to reconstitute functional genes in the macronucleus, is thought to depend on their recognition by Piwi-bound small RNAs (called scnRNAs) produced from the maternal germline genome during meiosis. This raises a problem during conjugation between strains presenting insertion polymorphisms: a cell will be theoretically unable to excise an IES from the incoming (paternal) allele if that IES is absent from the maternal allele, or if its sequence is too divergent. Our results, however, indicate that divergent paternal alleles are correctly rearranged, using scnRNAs produced by the paternal cell. In the case of an absence/presence polymorphism, the IES we studied is excised in 70% of heterozygotes, also using paternal scnRNAs. We explored two hypotheses to explain how they can act. It could be either an early programming of the gametic nuclei or through cytoplasmic exchange of scnRNAs. My results seem to favor the latter. Overall, I showed that the lack of maternal scnRNAs is not a possible cause of hybrid dysgenesis. However, 30% of heterozygous F1 display a variable retention of the IES through an unknown mechanism. If this is true for all hemizygous IESs then it will have a strong deleterious effect on hybrid F1s and may contribute to reproductive isolation.

Health is often defined in terms of absence of disease or pathological processes, but this is a definition of exclusion and incomplete. For example, SARS-CoV-2 viral load does not reliably predict disease severity, and so individuals must vary in their ability to control inflammation and maintain normal tissue homeostasis. This host defense strategy is called disease tolerance, and better understanding of disease tolerance mechanisms could change the way that we treat disease and work to maintain health. The first project presented in this dissertation found that after accounting for effects of age and sex, innate lymphoid cells (ILCs), but not T cells, were lower in adults and children sick with COVID-19 or MIS-C, independent of lymphopenia. Furthermore, abundance of ILCs, but not of T cells, correlated inversely with disease severity. These blood ILCs were shown to produce amphiregulin, a protein implicated in disease tolerance and tissue homeostasis, and the percentage of amphiregulin-producing ILCs was lower in males. These results suggest that, by promoting disease tolerance, homeostatic ILCs decrease morbidity and mortality associated with SARS-CoV-2 infection, and that lower ILC abundance accounts for increased COVID-19 severity with age and in males. The second project describes a novel mouse model of epigenetic inheritance wherein paternal influenza A virus (IAV) infection results in less severe influenza disease in IAV infected offspring. This offspring phenotype was not attributable to differences in viral load, indicating a possible difference in disease tolerance. Paternal caloric deprivation decreased, and influenza B virus infection increased, offspring influenza disease severity, and in vitro fertilization demonstrated sperm are sufficient to transfer IAV-associated epigenetic inheritance phenotypes. These findings represent a foundation for further work that, by continuing to elucidate the mechanisms of disease tolerance and epigenetic inheritance, could provide novel therapeutic interventions to help promote and maintain health.

Environmental stress has shown to affect both the exposed individuals and the development of their offspring. Generally, it is thought that the stressed organism responds to stress by trying to adapt to it. This thesis investigates possible evolutionary consequences of cross-generational transmissions of stress, where the parent has been stressed but the offspring has not. In two studies we have exposed chicken parents of different breeds to an unpredictable circadian light rhythm, to investigate the influence of genetic background on the transmission of behaviour and patterns of genome-wide gene expression across generations. In Paper I, we can show that the domesticated chicken, by means of epigenetic factors, transmit their behaviours as well as their gene expression profiles to their offspring to a higher extent than their wild ancestor, the red junglefowl. Furthermore, in Paper II, even though the offspring never experienced the stress or had any contact with their stressed parents, they seemed to have adapted to it, which suggests that the parents might have prepared (or pre-adapted) them for living in the unpredictable environment. Additionally, eggs of stressed hens showed increased levels of estradiol that might have affected gene expression of specific immune genes, which were up-regulated in the offspring of stressed parents. It is possible that the traditional distinction between stress responses and evolutionary adaptation may be reevaluated, since our results indicate that they could be parts of the same evolutionary event.

<p>Environmental stress has shown to affect both the exposed individuals and the development of their offspring. Generally, it is thought that the stressed organism responds to stress by trying to adapt to it. This thesis investigates possible evolutionary consequences of cross-generational transmissions of stress, where the parent has been stressed but the offspring has not. In two studies we have exposed chicken parents of different breeds to an unpredictable circadian light rhythm, to investigate the influence of genetic background on the transmission of behaviour and patterns of genome-wide gene expression across generations. In Paper I, we can show that the domesticated chicken, by means of epigenetic factors, transmit their behaviours as well as their gene expression profiles to their offspring to a higher extent than their wild ancestor, the red junglefowl. Furthermore, in Paper II, even though the offspring never experienced the stress or had any contact with their stressed parents, they seemed to have adapted to it, which suggests that the parents might have prepared (or pre-adapted) them for living in the unpredictable environment. Additionally, eggs of stressed hens showed increased levels of estradiol that might have affected gene expression of specific immune genes, which were up-regulated in the offspring of stressed parents. It is possible that the traditional distinction between stress responses and evolutionary adaptation may be reevaluated, since our results indicate that they could be parts of the same evolutionary event.</p>