# Cell-specific responses of Anopheles gambiae fat body to blood feeding and infection at single-nuclei resolution

## TL;DR

This study maps the fat body cells of Anopheles gambiae mosquitoes, revealing how they respond to blood feeding and infection.

## Contribution

The study provides a high-resolution atlas of fat body cell types and their specialized roles in immunity and reproduction.

## Key findings

- Blood feeding induces transcriptomic changes, endoreplication, and metabolic shifts in trophocytes.
- Oenocytes increase lipid biosynthesis enzyme expression after immune priming.
- T4 trophocytes consistently express immune genes, while multiple cell types respond to infection.

## Abstract

The mosquito fat body plays key roles in metabolism and immunity, yet its cellular diversity and specialization remain poorly understood. This study analyzed 97,650 nuclei from the female Anopheles gambiae abdominal body wall at single-nucleus resolution, identifying seven major cell types. Fat body trophocytes are most abundant ( ~ 85%), with five subpopulations: basal (T1, T2), metabolically enriched (T3), immune-responsive (T4), and a vitellogenic group (T5) found only in blood-fed females. Sessile hemocytes comprise 7.4% of cells and expression of lipid biosynthesis enzymes increase in oenocytes (1.1%) after immune priming. T4 trophocytes consistently express immune genes, while various cell types respond to bacterial infection. Blood feeding induces extensive transcriptomic changes, notably upregulating vitellogenin and DNA replication genes, indicating trophocyte endoreplication and metabolic shifts. Vitellogenin mRNA was expressed in the first layer of trophocytes facing the hemolymph with apical subcellular localization. This high-resolution atlas reveals specialized trophocyte roles in mosquito immunity and reproduction.

The mosquito fat body plays key roles in metabolism and immunity. Here, using single-nuclei transcriptomics the authors reveal that blood feeding induces extensive transcriptomic changes, endoreplication and metabolic shifts in fat body trophocytes, while oenocytes respond to immune priming.