Paternal mitochondria from an rmd-2, rmd-3, rmd-6 triple mutant are properly positioned in the C. elegans zygote

RMD-1,2,3,6 (regulator of microtubule dynamics) is a family of homologous proteins conserved between humans and C. elegans. Human RMD-3/PTPIP51 is a mitochondrial protein that tethers mitochondria to the endoplasmic reticulum. C. elegans RMD-2, 3, and 6 are expressed in sperm. To test whether paternal RMD-2, 3, 6 might redundantly tether paternal mitochondria to maternal ER at fertilization, we generated an rmd-2, rmd-3, rmd-6 triple mutant. Paternal mitochondria derived from control or triple mutant worms were concentrated in a cloud around the paternal DNA at the future posterior end of zygotes during meiosis. No significant difference was detected in the position of paternal mitochondria within the zygote nor in the position of paternal mitochondria relative to paternal DNA within the zygote. There was also no reduction in progeny viability between control and triple mutant worms.