Contrasting patterns of mitochondrial redistribution in the early lineages of Caenorhabditis elegans and Acrobeloides sp. PS1146

Abstract

We compared the redistribution of mitochondria in the early embryos of Caenorhabditis elegans (C. elegans) and Acrobeloides sp. PS1146 (Acrobeloides)--two nematode species where the mechanisms for embryonic axis specification are different even though subsequent development is remarkably similar. During the first cell cycle of C. elegans, mitochondria move with the bulk cytoplasmic flows that are directed toward the sperm pronucleus and aggregate at the posterior cortex during the period known as "pseudocleavage." In contrast, in Acrobeloides embryos, where prominent cytoplasmic rearrangements are absent, mitochondria that are initially distributed loosely around the pronuclei and the cytoplasm are relocated around the mitotic spindle prior to cell division. Interestingly, this rearrangement is reiterated only in the germline and not the somatic lineage. In both species, the location of the mitochondria immediately prior to cell division correlates with the known location of the germline determinants, P granules, leading us to speculate that they may be associated.