A flock of wild geese from the north seems to be flying in front of the autumn moon rising behind a place of scenic beauty. No, it’s not. Looking carefully, it is a shoal of sperms swimming toward an ovum. It seems that one sperm has reached the ovum and passed through the zona pellucida, and that fertilization has just taken place.
Mutations in PARKIN or PINK1 genes can cause autosomal recessive juvenile Parkinson's disease. In recent years, it has been revealed that they participate in mitochondrial quality control. Their products, Parkin and PINK1, modify dysfunctional mitochondria with polyubiquitin chains to promote selective autophagy (mitophagy) that eliminates dysfunctional mitochondria from cells. The woman in this drawing is removing unwanted seeds from the watermelon just as mitophagy eliminates dysfunctional mitochondria.