Electron microscopy of Drosophila garland cell nephrocytes: Optimal preparation, immunostaining and STEM tomography.

Due to its structural and molecular similarities to mammalian podocytes, the Drosophila nephrocyte emerged as a model system to study podocyte development and associated diseases. Similar to podocytes, nephrocytes establish a slit diaphragm between foot process-like structures in order to filter the hemolymph. One major obstacle in nephrocyte research is the distinct visualization of this subcellular structure to assess its integrity.

Distinct functions of Crumbs regulating slit diaphragms and endocytosis in Drosophila nephrocytes.

Mammalian podocytes, the key determinants of the kidney's filtration barrier, differentiate from columnar epithelial cells and several key determinants of apical-basal polarity in the conventional epithelia have been shown to regulate podocyte morphogenesis and function. However, little is known about the role of Crumbs, a conserved polarity regulator in many epithelia, for slit-diaphragm formation and podocyte function. In this study, we used Drosophila nephrocytes as model system for mammalian podocytes and identified a conserved function of Crumbs proteins for cellular morphogenesis, nephrocyte diaphragm assembly/maintenance, and endocytosis.

Pals1 Haploinsufficiency Results in Proteinuria and Cyst Formation.

The nephron is the basic physiologic subunit of the mammalian kidney and is made up of several apicobasally polarized epithelial cell types. The process of apicobasal polarization in animal cells is controlled by the evolutionarily conserved Crumbs (CRB), Partitioning-defective, and Scribble protein complexes. Here, we investigated the role of protein associated with LIN-7 1 (Pals1, also known as Mpp5), a core component of the apical membrane-determining CRB complex in the nephron.

Advanced electron microscopic techniques provide a deeper insight into the peculiar features of podocytes.

Podocytes constitute the outer layer of the glomerular filtration barrier, where they form an intricate network of interdigitating foot processes which are connected by slit diaphragms. A hitherto unanswered puzzle concerns the question of whether slit diaphragms are established between foot processes of the same podocyte or between foot processes of different podocytes. By employing focused ion beam-scanning electron microscopy (FIB-SEM), we provide unequivocal evidence that slit diaphragms are formed between foot processes of different podocytes.

Packing in endonasal surgery.

Nasal packing is used to control bleeding in epistaxis and after endonasal surgery, for internal stabilization, and to prevent synechiae or restenosis, particularly after surgery. Generally accepted standards regarding the materials that should be used for packing, how long the packing should be left in place, or the indications for nasal packing are lacking. In view of the present lack of standardization and the many different packing materials used, we review the currently available materials and outline their respective properties, indications, and risks.