Biology subjects

Librach, C. L.

Publications and source records attributed to Librach, C. L..

3 recordsLinked to original sources

bioRxiv2025

Altered sperm DNA methylation in overweight men associates with transposable element regulation of paternal origins of risk in children

The occurrence of childhood neurodevelopmental disorders has been steadily increasing for decades yet we have little understanding of modes of inheritance implicated in these diseases. Epidemiology studies have revealed an association between an elevated paternal BMI and an increased risk for autism in children, suggesting non-genetic modes of inheritance may be involved. Epigenetic marks, like DNA methylation at cytosines, are especially susceptible to environmental, diet and lifestyle changes. Yet, whether a mans BMI influences the sperm methylome and potentially impacts offspring development remains unresolved. Using MethylC capture (MCC)-sequencing, we identified over 38 000 differentially methylated CpGs (DMCs) in the sperm of men with an elevated BMI, with many occurring in regions that were enriched for neural gene and disease ontologies. Differentially methylated regions (DMRs) were enriched at transposable elements that can act as active enhancers during human zygotic genome activation, and at gene promoters for early lineage specification. These results suggest that sperm methylome alterations that are linked to an elevated BMI may influence key embryonic transcriptional process, notably those associated with trophectoderm and placental development.

developmental biology↗

bioRxiv2021

The lifetime cost of reproductive potential, who spends the most?

ObjectivesTo determine who spends more energy over a lifetime on maintaining their reproductive potential: men or women? DesignAs a model and energetic equivalent, we set the mass of gametes supported over time from birth until exhaustion of fertility. We calculated gender-specific dynamics of gamete pool mass over time. To this purpose we collated data from existing literature, accounting for gamete volume over stages of development, time in each stage, mass density, and count. Our model generates the integral, or area under the curve (AUC) of the gamete pool mass over a lifetime as a proxy to energetic requirements. Main outcome measuresThe area under gamete mass curve over a lifetime in men and women. ResultsThe number of gametes over a lifetime is 600,000 in women and close to 1 trillion in men. Accounting for mass and time, women invest approximately 100 gram*days in maintaining the female oocyte pool. Women reach 50% of lifetime AUC by age 10, and 90% by age 25. Men invest approximately 30 Kg*days over a lifetime (300-fold more), reaching 50% of lifetime AUC at age 37 and 90% at age 62 years old. ConclusionsThe study quantifies for the first time the area under gamete mass in men and women through a nuanced calculation accounting for all components of post-natal gamete dynamics. We found a 300-fold excess is supported male gamete mass over a lifetime (100g*days vs. 30 Kg*days in females vs. males, respectively). Our methodology offers a framework for assessing other components of the reproductive system in a similar quantitative manner.

physiology↗

bioRxiv2018

Towards Improving Embryo Selection: Simultaneous Next Generation Sequencing Of DNA And RNA From A Single Trophectoderm Biopsy

Improved embryo selection is crucial in optimizing the results from assisted reproduction. Preimplantation genetic screening reduces time to pregnancy and miscarriages. Correlating the transcriptome of an embryo, with fertility treatments and outcomes, holds promise in improving the overall results. We developed a novel method for embryo selection in fertility treatments that integrates embryonic genomic and transcriptomic data and evaluated it in this pilot study.\n\nA total of 21 embryos donated for research were included. Three were used for the initial development and optimization of sample processing and sequencing. Thereafter, 18 embryos were used to demonstrate the clinical safety and reproducibility of our method. Two trophectoderm biopsies were taken from each embryo: one was processed as a clinical sample for genomic profiling (control, n=18), while the other biopsy (n=18) was split and utilized for independent, simultaneous genomic and transcriptomic analysis, here termed Preimplantation Genetic and Transcriptomic Testing (PGT2).\n\nHigh quality genomic and transcriptomic data were obtained from all analyzed samples. The concordance between genomic data obtained with PGT2 and control samples was 100% with clinical grade quality metrics. Euploid embryos showed downregulation of genes involved in anaerobic metabolism, oxidative phosphorylation, and fatty-acid oxidation. This is the first study to provide full genomic and transcriptomic profiles from a single TE biopsy from human embryos in a clinical setting unleashing the potential of improving embryo selection and outcomes in infertility treatments. Clinical trials are needed to correlate transcriptomic data with outcomes.\n\nSUMMARYDespite advances in assisted reproductive technologies, the success rate has remained relatively constant. Under the age of 35, there is a 40% chance of delivering a child per embryo transfer, which decreases with increasing maternal age. Prioritizing embryos for transfer is based on morphological assessment and, in some cases, incorporates genetic testing as well. Selection of euploid embryos for transfer shortens the time to pregnancy and reduces the risk for miscarriages. Adding the mRNA analysis to the genomic assessment of an embryo has the potential of improving the outcomes of fertility treatments.

developmental biology↗