Ultrastructure Expansion Microscopy applied to embryos.

Visualization of organelles using expansion microscopy has been previously applied to adult gonads or worms. However, its application to embryos has remained a challenge due to the protective eggshell barrier. Here, by combining freeze-cracking and ultrastructure expansion microscopy (U-ExM), we demonstrate a four-time isotropic expansion of embryos.

Cosegregation of recombinant chromatids maintains genome-wide heterozygosity in an asexual nematode.

In asexual animals, female meiosis is modified to produce diploid oocytes. If meiosis still involves recombination, this is expected to lead to a rapid loss of heterozygosity, with adverse effects on fitness. Many asexuals, however, have a heterozygous genome, the underlying mechanisms being most often unknown.

Programmed DNA elimination in Mesorhabditis nematodes.

Some species undergo programmed DNA elimination (PDE), whereby portions of the genome are systematically destroyed in somatic cells. PDE has emerged independently in several phyla, but its function is unknown. Although the mechanisms are partially solved in ciliates, PDE remains mysterious in metazoans because the study species were not yet amenable to functional approaches.