Project description:Although it is increasingly accepted that some paternal environmental conditions can influence phenotypes in future generations, it remains unclear whether phenotypes induced in offspring represent specific responses to particular aspects of the paternal exposure history, or whether they represent a more generic response to paternal “quality of life”. To establish a paternal effect model based on a specific ligand-receptor interaction and thereby enable pharmacological interrogation of the offspring phenotype, we explored the effects of paternal nicotine administration on offspring phenotype in mouse. We show that paternal exposure to chronic nicotine induced a broad protective response to xenobiotic exposure in the next generation. This effect manifested as increased survival following an injection of toxic levels of nicotine, was specific to male offspring, and was only observed after these offspring were first acclimated to low levels of nicotine for a week. Importantly, offspring xenobiotic resistance was documented not only for toxic nicotine challenge, but also for toxic cocaine challenge, indicating that paternal nicotine exposure reprograms offspring to become broadly resistant to environmental toxins. Mechanistically, the reprogrammed state was characterized by enhanced clearance of nicotine in drug-acclimated animals, and we found that isolated hepatocytes displayed upregulation of enzymes that metabolize xenobiotics. Taken together, our data show that paternal nicotine exposure induces a protective phenotype in offspring by enhancing metabolic tolerance to xenobiotics in the environment.
Project description:Parental exposure to environmental stress can result in an increased diseases risk in the offspring. Although literature on maternal contribution to hereditary diseases are growing, the paternal contribution is frequently underrecognized. Since human studies reported that 80% of transmitted mutations arise in the paternal germline, it is crucial to understand the mechanism underlying the paternally inherited genome instability. Ionizing radiation (IR) is a major source of mutagenesis through inducing DNA double-strand breaks (DSBs). Here, we used sex-separated C. elegans mutants to investigate the paternal contribution to IR-induced transgenerational effects. Specifically, we found that paternal exposure to IR leads to a transgenerational embryonic lethality, and this effect is only observed when the radiation exposure occurred close to the time of fertilization. In the offspring of the irradiated males (F1 generation), we detected various genome instability phenotypes, including DNA fragmentation, chromosomal rearrangement, and aneuploidy. These phenotypes are attributed to the usage of two error-prone repair machinery, the polymerase-theta mediated end joining (TMEJ) and the non-homologous End Joining (NHEJ). Surprisingly, depletion of a human histone H1.0 ortholog, HIS-24, can significantly rescue this transgenerational embryonic lethality. Moreover, this rescue effect is associated with the downregulation of heterochromatin marker histone 3 lysine 9 di-methylation (H3K9me2), and the knocking-down of heterochromatin protein, HPL-1, could mimic the rescue effect of HIS-24 depletion. We also noticed that removal of the histone H1 and heterochromatin marker could activate the error-free repair machinery, Homologous Recombination repair (HR), thus improving the viability of the offspring carrying paternally inherited DNA damage. Altogether, our work sheds light on the importance of paternal radiation exposure on the health of offspring. In addition, our work establishes a previously unknown mechanism underlying the transgenerational genome instability and provides a potential therapeutic target for preventing the hereditary diseases caused by paternal radiation exposure.
Project description:Development of the early embryo is thought to be mainly driven by maternal gene products and post-transcriptional gene regulation. Here, we used metabolic labeling to show that RNA can be transferred by sperm into the embryo. To identify genes with paternal expression in the embryo, we performed crosses of males and females from divergent C. elegans strains. RNA sequencing of mRNAs and small RNAs in the 1-cell hybrid embryo revealed that about two hundred paternal mRNAs are reproducibly expressed in the embryo, and that about half of assayed endogenous siRNAs and piRNAs are also of paternal origin. Together, our results suggest an unexplored paternal contribution to early development. To reveal the identity of paternal RNA molecules, we performed a cross of males and females from two divergent C. elegans strains because we reasoned that sequencing of embryonic RNA and SNP analysis should then identify and quantify maternal and paternal transcripts. These sequencing experiments were carried out in purified hybrid 1-cell embryos and comprised small RNAs and mRNAs. For comparison we sequenced mRNAs and small RNAs from the parental strains: paternal (Hawaiian males, CB4856) and maternal (fem-1(hc17ts)/TX189(OMA-1::GFP). For the annotation of strain specific mutations (SNPs) we sequenced mRNA and small RNAs extracted from whole worms. All experiments were performed in at least two independent biological replicates.
Project description:Seed development is sensitive to parental dosage, with excess maternal or paternal genomes creating reciprocal phenotypes. Paternal genomic excess results in extensive endosperm proliferation without cellularization and eventual seed abortion. We previously showed that loss of the RNA POL IV gene nrpd1 in tetraploid fathers represses seed abortion in paternal excess crosses. Here we show genetically that RNA-directed DNA methylation (RdDM) pathway activity in the paternal parent is sufficient to determine the viability of paternal excess seeds. The status of the RdDM pathway in paternal excess endosperm does not impact seed viability. Comparison of endosperm transcriptomes, DNA methylation, and small RNAs from balanced and paternal excess endosperm demonstrates that paternal excess seed abortion is unlikely to be dependent on either transposable element or imprinted gene mis-regulation. We suggest instead that loss of paternal RdDM modulates expression at a small subset of genes and desensitizes endosperm to paternal excess. Finally, using allele-specific transcription data, we present evidence of a transcriptional buffering system that up37 regulates maternal alleles and represses paternal alleles in response to excess paternal genomic dosage. These findings prompt reconsideration of models for dosage sensitivity in endosperm.
Project description:Paternal nicotine exposure can alter phenotypes in future generations. To explore whether paternal nicotine exposure affects the hepatic repair to chronic injury which would lead to hepatic fibrosis in offspring, we establish a paternal effect model based on nicotine exposure in mice.
Project description:The importance of fathers' engagement in care and its critical role in the offspring’s cognitive and emotional development is now well established. Yet, little is known on the underlying neurobiology due to the lack of appropriate animal models. In the socially monogamous and bi-parental prairie vole (Microtus ochrogaster), while most virgin males show spontaneous paternal behaviors (Paternal), others display pup-directed aggression (Attackers). Here we took advantage of this phenotypic dichotomy and used RNA-sequencing in three important brain areas to characterize gene expression associated with paternal behaviors of Paternal males and compare it to experienced fathers and mothers. This strategy allowed the identification of spontaneous paternal behaviors independently from fatherhood and pair-bonding. While Paternal males displayed the same range and extent of paternal behaviors than experienced Fathers, the nucleus accumbens (NAc) and medial preoptic area (MPOA) transcriptomes mainly reflected pair-bonded status or sex differences, respectively. The lateral septum (LS) transcriptome, however, primarily reflected phenotypic differences between Paternal and Attackers and suggested the involvement of the mitochondria, RNA translation, and protein degradation processes. Altogether, these observations highlight a marked structure- and phenotype-specific pattern of gene expression underlying paternal behaviors in prairie voles and highlight similarities and differences from those underlying fatherhood.
Project description:DNA demethylation of paternal genome in zygotes takes place in various mammals including mice and human. Recent studies have revealed that this is achieved through Tet3-mediated iterative oxidation of 5-methylcytosine (5mC) coupled with replication-dependent dilution. Tet3-mediated paternal DNA demethylation is believed to be required for mouse development given that Tet3 heterozygous embryos, derived by fertilizing Tet3 knockout (KO) oocytes with wild-type (WT) sperms, exhibit 5mC oxidation defects and embryonic sublethality, Here we demonstrate that the sublethality phenotype of the maternal KO mice is caused by haploinsufficiency of Tet3, but not by defective paternal 5mC oxidation. We found that Tet3 heterozygous mice derived from crosses of heterozygous father or mother with WT mice also exhibit sublethality phenotype similarly to Tet3 maternal KO mice. Importantly, embryos reconstituted with WT paternal nuclei that bypassed 5mC oxidation develop to term and grow to adulthood normally. Genome-scale DNA methylation analysis of the maternal KO zygotes and blastocysts demonstrated that hypermethylation caused by the depletion of maternal Tet3 is largely diminished by the blastocyst stage. Our study thus not only demonstrates that Tet3-mediated paternal 5mC oxidation is dispensable for mouse development but also suggests the existence of a compensation mechanism in preimplantation embryos that can compensate for the defective 5mC oxidation in zygotes. This data set includes RRBS data of wild-type and maternal Tet3 KO zygotes and blastocysts (C57BL/6J x CAST/EiJ)
Project description:With the exception of imprinted genes and certain repeats, DNA methylation is globally erased during pre-implantation development. Recent studies have suggested that Tet3-mediated oxidation of 5-methylcytosine (5mC) and DNA replication-dependent dilution both contribute to global paternal DNA demethylation, but demethylation of the maternal genome occurs via replication. Here we present genome-scale DNA methylation maps for both the paternal and maternal genomes of Tet3-depleted and/or DNA replication-inhibited zygotes. In both genomes, we found that inhibition of DNA replication blocks DNA demethylation independently from Tet3 function, and that Tet3 facilitates DNA demethylation by coupling with DNA replication. For both, our data indicate that replication-dependent dilution is the major contributor to demethylation, but Tet3 plays an important role, particularly at certain loci. Our study therefore both defines the respective functions of Tet3 and DNA replication in paternal DNA demethylation and reveals an unexpected contribution of Tet3 to demethylation of the maternal genome. In this data set, we include RRBS data of manually isolated paternal and maternal pronuclei from both WT and Tet3 CKO zygotes with or without aphidicolin treatment
Project description:Development of the early embryo is thought to be mainly driven by maternal gene products and post-transcriptional gene regulation. Here, we used metabolic labeling to show that RNA can be transferred by sperm into the embryo. To identify genes with paternal expression in the embryo, we performed crosses of males and females from divergent C. elegans strains. RNA sequencing of mRNAs and small RNAs in the 1-cell hybrid embryo revealed that about two hundred paternal mRNAs are reproducibly expressed in the embryo, and that about half of assayed endogenous siRNAs and piRNAs are also of paternal origin. Together, our results suggest an unexplored paternal contribution to early development.