| Popis: |
Haemolysis in vitro of bovine erythrocytes by posterior midgut homogenate from stable flies displayed a sigmoidal pattern. The addition of soybean trypsin inhibitor to mixtures of midgut homogenate and erythrocytes reduced haemolytic and proteolytic activity equally. Scanning electron microscopy revealed that erythrocytes exposed to homogenate immediately transformed into echinocytes which released microvesicles from their membrane spicules. Subsequently, membrane spicules became blunt and cells developed membrane invaginations. Finally, at the onset and during the phase of rapid cell lysis, smooth spherocytes were formed. Some of these spherocytes had a single hole of about 1 μm in their plasma membrane which allowed intracellular material to escape. The morphological changes during the process of haemolysis were influenced by soybean trypsin inhibitor. However, the inhibitor did not impair the initial formation of echinocytes, but membrane invaginations and membrane holes were not noticed. Furthermore, cell ghosts remained in the presence of the soybean trypsin inhibitor even after haemolysis was completed. Haemolytic activity of homogenates was markedly reduced when bovine serum albumin was added to the assay medium. Albumin noticeably suppressed the formation of echinocytes. A mechanism for the haemolysis of bovine erythrocytes by midgut homogenate including detergent-like and enzymatic activities is presented. |
