Embryonic origin of hemocytes and their relationship to cell death in Drosophila

Abstract

We have studied the embryonic development of Drosophila hemocytes and their conversion into macrophages. Hemocytes derive exclusively from the mesoderm of the head and disperse along several invariant migratory paths throughout the embryo. The origin of hemocytes from the head mesoderm is further supported by the finding that in Bicaudal D, a mutation that lacks all head structures, and in twist snail double mutants, where no mesoderm develops, hemocytes do not form. All embryonic hemocytes behave like a homogenous population with respect to their potential for phagocytosis. Thus, in the wild type, about 80–90% of hemocytes become macrophages during late development. In mutations with an increased amount of cell death (knirps; stardust; fork head), this figure approaches 100%. In contrast, in these mutations, the absolute number of hemocytes does not differ from that in wild type, indicating that cell death does not ‘induce’ the formation of hemocytes. Finally, we show that, in the Drosophila embryo, apoptosis can occur independently of macrophages, since mutations lacking macrophages (Bicaudal D; twist snail double mutants; torso4021) show abundant cell death.

Characterization of the Drosophila Adult Hematopoietic System Reveals a Rare Cell Population With Differentiation and Proliferation Potential

“…Plasmatocytes and crystal cells are first produced in the embryo after a small group of prohemocytes emerges from the early head mesoderm and differentiates ( Tepass et al, 1994 ; Lebestky et al, 2000 ; Bataille et al, 2005 ). These embryo-derived hemocytes compose the larval peripheral blood cells, which are observed either as free circulatory cells in the hemolymph or attached under the cuticle ( Holz et al, 2003 ; Makhijani et al, 2011 ).…”

The Cellular Innate Immune Response of the Invasive Pest Insect Drosophila suzukii against Pseudomonas entomophila Involves the Release of Extracellular Traps

“…D. suzukii robust cellular immune responses might have facilitated its rapid worldwide spread by allowing it to overcome pathogen infections in newly colonized environments [ 55 , 56 , 57 ]. Such immunological diversity can help invasive species deal with unfamiliar pathogens [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ], as recently shown for the invasive harlequin ladybird Harmonia axyridis [ 48 , 55 , 56 , 57 ...…”

“…Plasmatocytes are small, spherical cells capable of phagocytosis. They originate in the procephalic mesoderm and migrate to colonize the entire embryo, making up the majority of all hemocytes in vivo [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Plasmatocytes act as macrophages by recognizing and eliminating microorganisms and apoptotic cells [ 19 , 20 , 21 ].…”

Drosophila as a Model to Study Cellular Communication Between the Hematopoietic Niche and Blood Progenitors Under Homeostatic Conditions and in Response to an Immune Stress

“…In flies, blood/immune cells are called hemocytes and are related to vertebrate myeloid cells Drosophila hematopoiesis occurs in two waves during development (19,20). The first wave takes place during embryogenesis (21). A cluster of cells derived from the head mesoderm gives rise to hematopoietic progenitors, which differentiate into plasmatocytes and crystal cells.…”

“…A cluster of cells derived from the head mesoderm gives rise to hematopoietic progenitors, which differentiate into plasmatocytes and crystal cells. Plasmatocytes, which are involved in phagocytosis of cellular debris and pathogens, are equivalent to mammalian macrophages (21)(22)(23)(24). Crystal cells contain crystalline inclusions of prophenoloxidases, which are required for the synthesis of melanin (25,26) and are involved in clotting and wound healing (27)(28)(29).…”