Cell surface exposure of phosphatidylserine during apoptosis is phylogenetically conserved.

Exposure of the aminophospholipid phosphatidylserine at the outer leaflet of the plasma membrane by apoptotic cells can trigger phagocytic removal of these dying cells. This functionality of phosphatidylserine exposure in the process of phagocytosis is indicated by in vitro studies of mammalian and insect phagocytes. We have studied the in vivo distribution of cell-surface exposed phosphatidylserine by injecting biotinylated Annexin V, a Ca2+ -dependent phosphatidyl-serine binding protein, into viable mouse and chick embryos and Drosophila pupae.

Spatiotemporal distribution of dying neurons during early mouse development.

Apoptosis is a critical cellular event during several stages of neuronal development. Recently, we have shown that biotinylated annexin V detects apoptosis in vivo in various cell lineages of a wide range of species by binding to phosphatidylserines that are exposed at the outer leaflet of the plasma membrane. In the present study, we tested the specificity by which annexin V binds apoptotic neurons, and subsequently investigated developmental cell death in the central and peripheral nervous system of early mouse embryos at both the cellular and histological level, and compared the phagocytic clearance of apoptotic neurons with that of apoptotic mesodermal cells.

In situ detection of apoptosis during embryogenesis with annexin V: from whole mount to ultrastructure.

Apoptosis is of paramount importance during embryonic development. This insight stems from early studies which correlated cell death to normal developmental processes and now has been confirmed by linking aberrant cell death patterns to aberrant development. Linking apoptosis to the phenotype of a developing organism requires spatial information on the localization of the dying cells, making in situ detection essential This prerequisite limits the tools available for such studies (1) to vital dyes, which can be detected at the whole mount level only; (2) to detection based upon apoptotic morphology by routine light microscopy and electron microscopy; and (3) to staining for apoptosis associated DNA fragmentation via, e.

Phosphatidylserine plasma membrane asymmetry in vivo: a pancellular phenomenon which alters during apoptosis.

The distribution of phospholipids across the two leaflets of the plasma membrane is important for many cellular processes including phagocytosis and hemostasis. In the present study we investigated the in vivo plasma membrane distribution of the aminophospholipid phosphatidylserine in mouse embryos with a novel technique employing Annexin V, a Ca2+ dependent phosphatidylserine binding protein, conjugated to fluorescein isothiocyanate and biotin. Annexin V directly applied to cryostat sections labeled the plasma membrane of all cells at the interface.