Application of cryosubstitution in neurohormone- and neurotransmitter-immunocytochemistry.

Pituitaries of the African catfish, Clarias gariepinus, were prefixed in aldehyde fixatives, frozen in liquid propane and submitted to a cryosubstitution procedure. Ultrathin sections of the Lowicryl HM20-embedded tissue were treated with primary antisera raised in rabbits to gonadotropin releasing hormone (GnRH), vasopressin or gamma amino butyric acid (GABA) respectively. Binding of the primary antisera was visualized with goat anti-rabbit (GAR) labeled with gold.

Characterisation and functional aspects of monoclonal antibodies specific for surface proteins of coagulase-negative staphylococci.

Mouse monoclonal antibodies (MAbs) raised against whole cells of Staphylococcus epidermidis strain 354 were characterised morphologically and functionally. Nine MAbs showed strong reactivity with coagulase-negative staphylococci (CNS). Only two MAbs were specific for CNS; both belonged to the IgG1 subclass, and one, MAb 36.

Epidermal growth factor receptors associated to cytoskeletal elements of epidermoid carcinoma (A431) cells.

The structural interaction of the epidermal growth factor (EGF) receptor and the cytoskeleton of A431 cells has been studied using a monoclonal anti-EGF receptor antibody. This has been done with immunogold labeling using a variety of electron microscopical preparation procedures and EGF binding studies. By providing an image of the membrane-associated cytoskeleton, the dry cleavage method reveals a preferential localization of EGF receptors superimposed upon cytoskeletal filaments.

Freeze-fracture studies of human blood platelets activated by thrombin using rapid freezing.

In this study the influence of thrombin activation on human blood platelets has been followed by freeze-fracturing electron microscopy using rapid freezing in order to catch the initial changes in shape and the morphological alterations during the process of exocytosis of secretory granules. We found that isolation of the platelets by itself leads to some degree of shape change, which made it impossible to study the resting discoid platelet by rapid freezing. Activation of the platelets by thrombin induced dilation of the "surface connecting system (SCS)" with formation of large vacuoles as a result of fusion of the secretory granules with SCS.

Visualization of epidermal growth factor receptor in cryosections of cultured A431 cells by immuno-gold labeling.

Cryo-ultramicrotomy in combination with immuno-gold labeling has been demonstrated to present a powerful tool in the visualization of extra- and intracellular located antigens. We have applied this method to localize epidermal growth factor (EGF) receptor in cultured A431 human epidermoid carcinoma cells. However, both the labeling efficiency, maintenance of antigenicity, and the recognizability of the ultrastructure in cryosections are highly dependent upon the fixation procedures.