Toshchakov, S. | Search bioRxiv

bioRxiv2025

Dora, a key component of target-directed miRNA degradation, is essential for local genomic amplification in Drosophila ovarian follicle cells

The ubiquitin ligase receptor Dora, the Drosophila homolog of ZSWIM8, is a key component of the target-directed microRNA degradation (TDMD) pathway. Previous studies have implicated TDMD - and, consequently, ZSWIM8/Dora - in various developmental processes. Here, we investigate the role of Dora in Drosophila oogenesis, focusing on its function in ovarian somatic cells. We generated a fly strain with an endogenously tagged Dora protein and observed its presence in both germline and somatic follicular cells of the ovaries. Somatic knockdown of dora revealed its essential role in normal eggshell formation. Specifically, its loss led to reduced chorion and vitelline transcript levels and decreased chorion gene amplification, both of which are critical for eggshell protein production. Somatic depletion of Dora did not affect the abundance of other known regulators of eggshell formation, including Ttk69, Cut, miR-7 or miR-318 indicating that Dora functions independently of these pathways. Although a direct link between TDMD and chorion eggshell development remains to be confirmed, our findings clearly highlight Dora as a critical regulator in this process. These results pave the way for further investigation into the specific role of TDMD and provide new insights into the regulatory mechanisms underlying animal oogenesis.

developmental biology↗

bioRxiv2021

An interplay between viruses and bacteria associated with marine sponges from the White Sea revealed by metagenomics

Sponges are remarkable holobionts harboring extremely diverse microbial and viral communities. However, the interactions between the components within holobionts and between a holobiont and environment are largely unknown, especially for polar organisms. To investigate possible interactions within the sponge-associated communities and between them, we probed the microbiomes and viromes of cold-water sympatric sponges Isodictya palmata, Halichondria panicea, and Halichondria sitiens by 16S and shotgun metagenomics. We showed that the bacterial and viral communities associated with these White Sea sponges are species-specific and different from the surrounding water. Extensive mining of bacterial antiphage defense systems in the metagenomes revealed a variety of defense mechanisms. The abundance of defense systems was comparable in the metagenomes of the sponges and the surrounding water, thus distinguishing the White Sea sponges from those inhabiting the tropical seas. We developed a network-based approach for the combined analysis of CRISPR-spacers and protospacers. Using this approach, we showed that the virus-host interactions within the sponge-associated community are typically more abundant than the inter-community interactions. Additionally, we detected the occurrence of viral exchanges between the communities. Our work provides the first insight into the metagenomics of the three cold-water sponge species from the White Sea and paves the way for a comprehensive analysis of the interactions between microbial communities and associated viruses.

microbiology↗