Figure 7.

Unresolved features of systemic parental RNAi. Where is the dsRNA stored long‐term in the mother without degradation and with continuous transmission to eggs? Cartoons represent the progression of dsRNA from initial injection (A), through the mother's tissues (B) and cells (C,D), to the oocytes (E). In detail, we depict injection into the abdominal body cavity (A); clearance from the hemolymph (B, schematized representation of the dorsal vessel (heart) and major circulatory system branching structures such as arteries^{[ 91 ]}); uptake across the plasma membrane into individual cells, which may be receptor‐mediated (C); and potential sequestration from the cytosol in endosomes (D). Despite challenges associated with each of these steps (see Section 3.5), systemic parental RNAi involves dsRNA transmitted from the ovary into oocytes for months (E). Presence of dsRNA is represented in blue, with specific cell‐ and tissue‐scale challenges to its transmission shown in red, and with final waning of pRNAi indicated by pale blue and grey. Clip art images reproduced and modified from Microsoft PowerPoint 2021, v. 16.52; ovary silhouette based on image at https://cronodon.com/BioTech/Insect_Reproduction.html, adapted with permission.