Disruption of hemocyte differentiation and distribution in Drosophila Ptr ^23c mutants

In Drosophila , hemocytes are essential for development and immunity, with their differentiation and spatial distribution under strict regulation. Here, we examine the effect of the Ptr ^23c null mutation in embryonic hemocyte development. Contrary to our initial hypothesis, Ptr does not regulate hemocyte number, as the mutation did not affect the total number of hemocytes, apoptosis, mitosis, or the balance between major subpopulations. However, Ptr ^23c mutants displayed disrupted distribution and premature hemocyte differentiation, marked by accelerated maturation at stage 12. Despite this early differentiation, Ptr ^23c embryos exhibited a 50% reduction in mature hemocytes by stage 16, as quantified by serpent-driven mCherry expression. Our findings establish Ptr as a regulator of hemocyte distribution and differentiation timing during normal embryogenesis, possibly through modulation of the serpent pathway.