Electron microscopy of C. Sporogenes endospore attachment and germination

Abstract

Summary:The bacterial endospores of C. sporogenes ATCC 3584 are quite small (approximately 0.7-1.0 pm in length) and are difficult to examine during the attachment and germination process by conventional light microscopy methods. Although transmission electron microscopy provides high magnification and resolution, it has not been possible to date to visualize the attachment process and surface changes of intact clostridial endospores. With the advent of higher resolution conventional scanning electron microscopes (SEM), it is now possible to study these small spores attached to their nutrient substrate in their intact state and readily obtain detailed morphologic information about the attachment, germination, and outgrowth process. Spores were examined in their dormant, dehydrated state and allowed to germinate. Samples were prepared for light, transmission, and SEM under anaerobic conditions for morphologic and histochemical examination. SEM revealed that the spores developed a distinct polarity at the beginning of the germination process and that the exosporial membrane at this time produced projections that attached the spore to a substrate. These projections were altered by calcium chelation with EDTA and the presence of barium. Following colchicine and cytochalasin B treatment, the exosporial membrane projections were morphologically altered and the germination sequence was modified. Histochemical examination of the spores suggested that calcium was predominantly located in the protoplast and spore coat.

The Exosporium Layer of Bacterial Spores: a Connection to the Environment and the Infected Host

“…The exosporium is reported to have a protrusion, or "sporiduct," at one pole of the spore, which in some spores becomes an opening or aperture in the exosporium (195,196). Functions ascribed to the exosporium include roles in germination, outgrowth, and attachment (195,197). A recent report indicates that the germination and outgrowth process for C. sporogenes strain ATCC 15579 involves rupture of the spore coat at a site adjacent to the exosporium aperture (196).…”

Nanoparticle Interactions with Living Systems: In Vivo and In Vitro Biocompatibility

“…5B). This loss of cell adhesion to the coverslip and to adjacent cells in the monolayer has been described as indicative of nanoparticle cytotoxicity [3,5,10].…”

“…Nanoparticles can become bound to these cell-elaborated materials at the cell surface, and subsequently bind to cell surface receptors that facilitate entry of the nanomaterial into the cell (via endocytosis). This can result in the lysosomal digestion and processing of the nanoparticle within the cell with recycling of the adsorbed protein and the attached fragments of the plasma membrane (back to the cell), and the eventual expulsion from the cell of the intact or degraded nanoparticle [4,5]. Nanoparticles may also remain stored within phagocytic vacuoles or endosomal vesicles for indeterminate periods of time [14].…”

“…However, there was no visible evidence of endocytic vesicle formation, or some form of phagocytosis. These DNA functionalized gold nanoparticles were found in the apical cytoplasm, or localized within endoplasmic (ER) reticulum-like tubular channels at the apical surface [5]. They were later seen within the Golgi and finally within vacuoles in the central and basal portions of the cells.…”

“…• Or, complement fixation of the nanoparticles can lead to activation of cellular inflammatory responses, interference in the blood clotting cascade and subsequent fibrin formation and anaphylaxis [2] This lecture surveys some of the documented responses in the current scientific literature and original data of living biological systems following exposure to different types of nanoparticles, and how both biological factors, and nanoparticle compositional characteristics, as well as dose, exposure time and nanoparticle surface reactivity & functionalization collectively impact biocompatibility [3][4][5].…”