Just wrapped up another incredible Annual Meeting! Over 200 FMI scientists, Novartis colleagues and the FMI Scientific Advisory Board came together for insightful talks, engaging posters, and fun activities. Thanks to everyone who made it a success, looking forward to next year!

Today Dr. Mark Gill presented to @ESHRE how NicE-view detects the levels of DNA accessibility in human sperm across individuals with differing reproductive parameters. Find more here: https://t.co/y9bZ2jLn02

Excited to present our latest research at the European Society of Human Reproduction and Embryology conference @ESHRE ! Join Devico Shi and Dr. Mark Gill from @FMIscience and @UniSpitalBasel to explore the chromatin organization of mouse and human sperm!

Congratulations to all of the authors, and many thanks to the staff of the Andrology lab at the University Hospital Basel and the facilities at the FMI, without whom this work would be not have been possible.

We also show that a high frequency of sperm with high levels of DNA accessibility correlates with poor reproductive outcomes. All the participants in this study had normal fertilization rates, suggesting a post-fertilization function for sperm DNA packaging in human development.

Using an adaptation of the NicE-view technique, and a lot of quantitative fluorescence microscopy, we show that the packaging of sperm DNA varies dramatically between individual sperm within the same sample.

Happy to share our new preprint “Levels of DNA accessibility in human sperm vary across individuals with differing reproductive parameters” ( https://t.co/y9bZ2jLn02) the result of a fruitful collaboration with the University Hospital Basel. @FMIScience @UniSpitalBasel

Great support from FMI (@FMIscience) and Reproductive Medicine and Gynecological Endocrinology, University Hospital Basel (@UniSpitalBasel).

We anticipate that this protocol will facilitate reproductive biology research. We would like to thank Hubertus Kohler from FMI FACS facility and Antoine Peters (@AntoinePeters8 ) for their contributions.

We provide a detailed step to step description on 1) how to prepare and stain testicular single cell suspensions, 2) FACS sorting strategy and 3) quality control of sorted cells by immunofluorescence.

We developed a simple protocol for dual labeling of germ cells with Hoechst 33342 and SYTO16 that enables efficient separation by FACS of meiotic and post-meiotic cells from mouse testes into several highly pure sub-populations.

Happy to share the method regarding the “Isolation of Mouse Germ Cells by FACS Using Hoechst 33342 and SYTO16 Double Staining“ developed by Mark Gill published as a chapter of the Germ Cell Development Methods and Protocols book.

Thanks to all authors of the study Laura Gaspa-Toneu, Evgeniy Ozonov (@EvgenOzonov), Pavel Komarov, Sebastian Smallwood and Antoine Peters (@AntoinePeters8) at @FMIscience, FMI facilities and funding agencies @snsf_ch , @ERC_Research and @NovartisScience !

Our study provides proof of concept linking deposition of H3K4me3 on the paternal genome in early embryos to the DNAme status inherited from sperm. Understanding how chromatin transmits information across generations continues to be an exciting question!

We developed a highly sensitive chromatin profiling approach named Antibody TArgeted TAgmentation (ATATA) to measure H3K4me3 in early embryos. We found that aberrantly low DNAme in sperm renders paternal alleles in early embryos permissive for H3K4me3 deposition.

Loss of DNA methylation in spermatogonia promotes nucleosome retention at GC-rich sequences in sperm. ~30% of regions with increased nucleosome signal also displayed higher H3K4me3 enrichment.

By analyzing DNA methylation data from various populations of germ cells isolated from ctrl and Dnmt3a/Dnmt3bsingle or double mutant animals, we observe that DNMT3A and DNMT3B control maintenance and de novo DNAme respectively in spermatogonial cells.

We generated adult male germ cells lacking Dnmt3a and Dnmt3b by using an iCre recombinase transgene under the control of the Stra8 promoter. While spermatogenesis is completed, ~1% of the sperm genome is hypomethylated.

@PetersLabFMI: Excited to share our latest preprint lead by Greg Fanourgakis (@Grigo_Fanou). Key findings are that DNA methylation modulates nucleosome retention in sperm and H3K4 methylation deposition in early mouse embryos.

This work was led by Daniel Ballmer, Mathieu Tardat, Grigorios Fanourgakis @grigo_fanou and Antoine Peters @AntoinePeters8 along with the great support of imaging facility expert Alexandra Graff-Meyer at FMI @FMIscience.