Figure 6. | Symbiont-induced odorant binding proteins mediate insect host hematopoiesis

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Symbiont-induced odorant binding proteins mediate insect host hematopoiesis

Figure 6.

Affiliation details

University of Cincinnati, United States; Yale School of Public Health, United States; University of Connecticut, United States; Yale University, United States
Figure 6.
Download figureOpen in new tabFigure 6. Model illustrating the functional relationship between maternally-transmitted enteric symbionts and melanization in tsetse.

GmmWT larvae imbibe enteric symbiotic-containing milk gland secretions throughout their intrauterine developmental program. These bacteria colonize larval gut-associated tissues, including the bacteriome, and in doing so, induce the expression of obp6. OBP6 is either secreted directly into the hemolymph, or acts locally to induce expression of another unknown, (also secreted) protein. One of these molecules then acts systemically in the larval hematopoietic niche (hn) to stimulate lozenge (lz) expression in a small proportion of serpent (srp) expressing prohemocytes. These cells then become PPO-producing crystal cells [remaining prohemocytes become phagocytes after expressing glial cells missing (gcm)]. Finally, crystal cells are expelled from the hn, where they circulate in the hemolymph and are available to produce wound-healing melanin. Larvae that develop in the absence of symbiotic bacteria (GmmApo) fail to produce any hemocytes, while those that develop in the presence of reduced obp6 transcript abundance (GmmOBP6-) fail to express lozenge and thus likely fail to generate crystal cells. dv, dorsal vessel; hc, hemocoel; w, wound; ep, epithelial cells of midgut; bc, bacteriome; pm, peritrophic matrix; gl, gut lumen.