Formation of ring-shaped structures on erythrocyte membranes after treatment with botulinolysin, a thiol-activated hemolysin from Clostridium botulinum

Damage to erythrocyte membranes by botulinolysin (BLY) was studied by electron microscopy, which revealed ring-shaped structures with inner diameters and widths of approximately 32 and 6.7 nm, respectively. BLY bound to membranes at 0 degrees C, but subsequent treatment with glutaraldehyde prevented ring formation during further incubation at 37 degrees C. Zn2+ ions inhibited ring formation but not binding of BLY to membranes.

Characterization of the damage to membranes caused by bacterial cytolysins

The damage to cell membranes caused by bacterial cytolysins has been studied for many years. In this review, we attempt to summarize the historical contribution of electron microscopy to our understanding of the modes of action of pore-forming and channel-forming toxins. We describe the ways in which these toxins form holes in membranes by binding to and forming oligomers on biological membranes. We also introduce the new technique of electron spectroscopic imaging (ESI) with an imaging plate (IP), which has been used to analyse the mechanisms of membrane damage by cytolysins.

Electron microscopic evaluation of a two-step theory of pore formation by streptolysin O

The formation of pores by streptolysin O (SLO) was analyzed in erythrocyte membranes and liposomes by immunoelectron microscopy and electron spectroscopic imaging. The binding of SLO molecules to membranes was temperature independent, while the polymerization of SLO molecules was temperature dependent. Our results also suggest that proteins in erythrocyte membranes are not involved in the formation of SLO rings.

Brain activity of a rat reflects apparently the stimulation of acupuncture. A radioautography using 2-deoxyglucose

To confirm a relationship between the central nervous system and the acupuncture, the response was examined in the rat brain using radioautography with tritiated 2-deoxyglucose, after stimulation of some acupoints. Eight groups, of a total of 27 rats were submitted to acupuncture at 6 different acupoints (Zusanli, Renzhong, Tianshu, Shenmen, Neiguan, Yongquan) and control, with or without electric pulses or with anesthesia respectively, prior to the injection with isotopic deoxyglucose. A hundred twenty cryosections were cut from a freshly frozen brain and exposed on single-coated X-ray films. The results showed that the acupuncture on the four acupoints of Zusanli, Tianshu, Shenmen and Neiguan enhanced the activity of the neocortex, the limbic cortex and the thalamic nuclei in comparison with the control group. The acupoints on Renzhong and Yongquan depressed the activity on the thalamic nuclei and the midbrain. The anesthesia with pentobarbital concealed the most activity on the whole area of the brain, which hardly responded to any stimulation of acupuncture. These results lead to the suggestion that the brain may reflect the signals by the stimulation of acupuncture and change the activity depending upon each acupoint.

Immunohistochemical studies on thyroid peroxidase and thyroglobulin in 13 human thyroid tumors and 7 Graves' goiters

Thyroid peroxidase (TPO) in 4 benign tumors, 9 malignant tumors and 7 Graves' goiters was examined both by biochemical methods (guaiacol and iodide oxidation assays) and histochemical methods (indirect immunofluorescence methods with polyclonal anti-TPO antibodies). The protein-based specific activity of TPO of Graves' goiters was comparable to or higher than that of normal thyroid tissues, while that of benign and malignant tumors were comparatively lower and variable. TPO was stained with the polyclonal anti-TPO antibodies in the cytoplasm of all benign adenomas, Graves' goiters and follicular carcinomas, but not of papillary carcinoma and metastatic cells. TPO staining markedly appeared in apical areas of Graves' goiters but was scarcely detected in the areas of other disordered thyroids. Polyclonal anti-thyroglobulin antibodies detected thyroglobulin in the follicular lumen of these diseased thyroids except in metastatic carcinoma cells.

A ring-shaped structure with a crown formed by streptolysin O on the erythrocyte membrane

Streptolysin O (SLO) is a membrane-damaging toxin produced by most strains of group A beta-hemolytic streptococci. We performed ultrastructural analysis of SLO-derived lesions on erythrocyte membranes by examining electron micrographs of negatively stained preparations. SLO formed numerous arc- and ring-shaped structures with or without holes on membranes. Rings formed on intact cell membranes had an inner diameter of ca. 24 nm and had distinct borders of ca. 4.9 nm in width, but the diameter of rings varied from 24 to 30 nm on membranes of erythrocyte ghosts. Image analysis of electron micrographs demonstrated that each ring was composed of an inner and an outer layer. Each layer contained an array of 22 to 24 SLO molecules. On the top of the ring, we found a characteristic crown that projected from the cell membrane. The crown was separated by an electron-dense layer from the basal part of the ring that was embedded in the lipid bilayer of the erythrocyte membrane. Heights of the three parts, namely, the crown (head), the space (neck), and the basal portion (base), were ca. 3.2, 1.6, and 5.0 nm, respectively, and we postulated that these parts are the constituents of a single SLO molecule. The volumes of SLO molecules in the inner and outer layers were calculated to be 77 and 88 nm3. On the basis of a model of the structure of SLO, we propose some new details of the mechanisms of hemolysis by SLO toxin.

[Mechanism of pore formation on erythrocyte membrane by streptolysin-O]

The erythrocyte membrane damaged by streptolysin-O (SLO) was observed in negative staining electron microscopy. It was confirmed that rings took arc (c-ring), sigmoidal (s-ring) or circular (o-ring) structures, and had electron-dense centers of a diameter of 24 nm and 4.9 nm width. We found a crown structure on top of the ring in view of side projection. The ring structure was constructed by three layers of the electron lucent top which was the crown, the second dark layer, and the third, base part which embedded in the erythrocyte membrane, and the heights were 3.2, 1.6, 5.0 nm, respectively. When the ghost membrane of erythrocyte was treated with SLO, the double of the inner and outer layers of a ring were observed by the negative-staining images. The figures of rings taken by under focus showed that one ring might be constituted between the 22 and 24 pair of inner and outer molecules. Totally 44 or 48 toxin molecules might be required for one O-ring.

Cytotoxic effects of antitumor agents on mouse tracheal organ cultures at ultrastructural level

A cytotoxic effect of antitumor agents (mitomycin C;MMC, adriamycin;ADM, bleomycin;BLM, 5-fluorouracil;5-FU, and cisplatin;CDDP) on ciliated epithelial cells of mouse tracheal organ cultures was studied in transmission electron microscopy. Mouse tracheal rings incubated with each agent in a concentration of 1 microgram/ml or 10 micrograms/ml were observed after 1, 2, and 20 hr of the incubation. After 2 hr, the ciliated epithelial with MMC or ADM of 1 microgram/ml exhibited appearance of lipid droplets in the nonciliated cells and the swelling of mitochondria and epithelial cells. Further incubation of 20 hr with those agents resulted in the pronounced degeneration including the ciliary subsidence into intracellular spaces, balloon-like ciliary swelling, and cellular destruction. Whereas, the ciliated epithelia with 5-Fu, BLM or CDDP did not show any notable change within 2 hr. After 20 hr, these exhibited the swelling of mitochondria, cilia and epithelial cells. The ciliated epithelia incubated with MMC or ADM of a greater concentration of 10 micrograms/ml showed remarkable cytotoxic effects after 1 hr of the incubation. The morphological changes in the epithelial cells with 1 hr incubation were almost similar to those of 20 hr incubation with the 1 microgram/ml. After 20 hr, the cellular degeneration proceeded to extremely flattened epithelial cells with disappearance of cilia and appearance of numerous vacuoles. Those with 5-FU, BLM or CDDP of 10 micrograms/ml exhibited ciliary swelling after 2 hr, but the morphological changes of 5-FU were more remarkable than those of BLM or CDDP. After 20 hr, the pronounced degeneration was observed, and it was similar to one of MMC or ADM of 2 hr incubation.

In vitro differentiation of the human osteosarcoma cell lines, HOS and KHOS

The osteogenic potential of the two human osteosarcoma cell lines HOS and KHOS; a cell line produced by the transformation of the HOS cells by the Kirsten murine sarcoma virus, was studied in vitro. HOS cells cultured more than 2 weeks formed nodules composed of two morphologically distinct layers, an epithelial-like surface cell layer and a collagen-rich inner cell layer. Alkaline phosphatase (ALPase) activity occurred in the plasma membrane of the surface cell layer, and calcified substances developing along collagen fibers were detected in the collagen-rich inner cell layer. The calcified substances were further examined by analytical electron microscopy and were shown to be hydroxyapatite crystals. In contrast, there was neither ALPase nor the deposition of a calcified substance in the KHOS cells.

In vivo effect of thyrotropin on intracellular translocation of thyroid peroxidase in rat thyroid cells by an indirect immunofluorescence method

The in vivo effect of thyrotropin (TSH) on the intracellular localization of thyroid peroxidase (TPO) in rat thyroid epithelial cells was examined by an indirect immunofluorescence method. The staining for TPO in the epithelial cells of normal rats appeared all over the cytoplasm, especially in the apical region. The injection of propylthiouracil for 3-10 days increased the staining in the apical region. The administration of L-thyroxine for 7-10 days to normal rats abolished the relatively high localization of TPO in the apical region, and resulted in TPO staining all over the cytoplasm. Six hours after TSH was injected into the thyroxine-treated rats, localization of TPO staining in the apical region was observed. These results suggest that TSH may play a role in the translocation of preexisting TPO to the apical region before TSH-induced biosynthesis becomes evident.

A temperature-sensitive mutant of Newcastle disease virus defective in intracellular processing of fusion protein

A temperature-sensitive mutant (ts3) of Newcastle disease virus was physiologically characterized. All major viral structural proteins were synthesized at the permissive (37 degrees C) and nonpermissive (42 degrees C) temperatures, but the fusion (F) glycoprotein was not cleaved at 42 degrees C. In immunocytochemical electron microscopy, the F protein was abundant in the rough endoplasmic reticulum but not in cytoplasmic membrane at 42 degrees C. Noninfectious hemagglutinating virus particles containing all major structural proteins except the F protein were released at 42 degrees C from infected cells. We concluded that the defect in ts3 resides in the intracellular processing of the F protein.

Electron microscopic observations on ciliated epithelium of tracheal organ cultures infected with Bordetella bronchiseptica

Using mouse tracheal organ cultures, the pathogenic effect of Bordetella bronchiseptica to epithelial cells was studied by electron microscopy. The ultrastructure of epithelial cells in uninfected tracheal rings was preserved well for longer than 3 days. In mouse tracheal rings infected with graded doses (3 x 10(5) to 10(7) CFU/ml) of phase I B. bronchiseptica, the colonization in the interciliary spaces of ciliated epithelial cells was observed after a 20-hr infection period. The infected tracheal rings showed swelling of nonciliated cells as well as ciliated cells, rupture of cell membrane of cilia, swelling and disappearance of cilia, and atrophic cytomorphosis of epithelial cells. The severity of these changes occurred depending on the infection doses. These changes were essentially similar to those observed previously in the tracheal epithelia of the B. bronchiseptica-infected mice. The usefulness of this in vitro model was suggested for studying the pathogenesis of Bordetella infection.

Electron microscopic observations on tracheal epithelia of mice infected with Bordetella bronchiseptica

To clarify the pathogenesis of Bordetella in vivo infection, the tracheal epithelia of mice were examined in detail by electron microscopy at various intervals after intranasal inoculation with graded doses of phase I Bordetella bronchiseptica. In mice infected with a lethal dose (6 to 7 x 10(7) CFU), a remarkable rupture of the cell membranes of cilia and microvilli of the middle trachea was found on day I postinfection. The rupture of the membrane was observed over the entire tracheal epithelia, on day 2 after infection. The affected cilia were constricted at the transitional region and were broken off. In the ciliated cells the adherence of organisms to ciliary apexes and colonization in the interciliary spaces were also remarkable. In both the ciliated and nonciliated epithelial cells, the cytoplasmic vacuolation and pyknosis or karyorrehexis were also notable. In mice infected with one-tenth of the lethal dose, similar findings were seen, but appeared more slowly and the bacteria were not seen attaching to ciliary apexes. In mice receiving one-hundredth of the lethal dose, only mild cilial abnormality such as aggregation of cilia, and slight cytoplasmic vacuolation were found 6 days postinfection. Based on these findings, a possible mechanism of the ciliary damages produced by B. bronchiseptica was postulated.

[125I] triiodothyronine in the rat brain: evidence for neural localization and axonal transport derived from thaw-mount film autoradiography

Previous thaw-mount light microscopic autoradiographic studies have shown that intravenously administered [125I] triiodothyronine is saturably concentrated and retained for at least 10 hours in discrete neural systems in the rat brain. To survey the brain more completely and to gain information about the time course of labeling, serial thaw-mount film autoradiograms were prepared from rat brains obtained at intervals through 48 hours after intravenous injection of high specific activity [125I] triiodothyronine. Parallel biochemical studies of whole brain homogenate extracts revealed that, at all time intervals, the label in the brain was mainly due to triiodothyronine itself (80%), or other organic iodocompounds (15%), but probably not due to free [125I] iodide (3%), which is rapidly transported out of the brain. The highly reproducible, well-defined labeling patterns seen on film indicated a widespread but selective localization of the hormone. At early times after intravenous injection of [125I] triiodothyronine, label was nonuniformly and prominently concentrated in selected regions of gray matter; evidence for saturability of hormone processing was obtained in competition studies with unlabeled triiodothyronine. Discrete labeling of fiber tracts (usually after 10 hours) left some regions of white matter conspicuously unlabeled. At 48 hours, many originally labeled gray regions showed markedly diminished or virtually complete loss of radioactivity, whereas others became newly or more prominently labeled. At that time, certain fiber tracts were also conspicuously labeled. The observed changing profiles of regional labeling over time are best explained by movement of the hormone from original sites of saturable incorporation in specific nuclei, to terminal fields, through the mechanism of axonal transport.

Negative-staining autoradiography: a new technique for ultracryotomy utilizing an interposed film

A new radiocytochemical technique is reported for ultrastructural localization of diffusible substances, using negatively stained ultra-cryostat sections. A sheet of film interposed between the cryostat section and the emulsion layer has rendered negative-staining autoradiography (NSA) practical. The rationale of NSA is that the film completely shields the section from all moisture-producing autoradiographic processes, so that phosphotungstic acid (PTA) can stain the section either before or after autoradiography (ARG), without the possibility of ultrastructural damage by alkaline solutions, interference between PTA and photoprocessing compounds, and superimposed images of a gelatin layer stained with PTA. As a model to demonstrate the newly developed procedure of NSA, rat brains were labeled with [125I]-triiodothyronine, fixed with tannic fixative, immersed in a cryoprotectant, frozen in liquefied propane, and cryostat sectioned. The resulting higher yield of radioactivity (85%) on the section was confirmed by a radiation counter. The retention rate was approximately 20% greater than that of conventional sections. Developed silver grains were found on synaptic vesicles and mitochondria in the polymorphic layer of the dentate gyrus. In this report we will also discuss the problems associated with cryostat sectioning of fresh tissues, the concept of ARG resolution, the distribution pattern of developed silver grains, and the possible applications of NSA.

The fine structure of the spermatozoa of two species of Rhacophorus (arboreus, schlegelii). I. Phase-contrast microscope, scanning electron microscope, and cytochemical observations of the head piece

Green tree frogs, Rhacophorus arboreus and Rhacophorus schlegelii, living on the main island of Japan have spermatozoa in the form of a counterclockwise corkscrew composed of about 20 coils arranged in the shape of a cone. A head piece coiled loosely and tightly 5-6 times each. It was composed of two subcoils, one outside and the other inside. The outside subcoils composed the nuclear head, and the inside coils the acrosome. Following the head piece, a middle piece which had a mitochondrial sheath coiled 1 1/2 times. A tail piece which followed the middle piece coiled 3-10 times irregularly in 5-6 microns width with a 20- to 30-microns straight tail in length. There was a crystalline composed of 500-600 microtubules which surrounded a pair of cilial structures in the tail piece. The tannic acid-aldehyde-osmium tetroxide fixation method produced excellent electron density and good electron conductivity for scanning electron microscope observations.

Iodine-125-labeled triiodothyronine in rat brain: evidence for localization in discrete neural systems

Autoradiograms prepared from adult rat brains demonstrate that nerve cells and neuropil in different brain regions selectively concentrate and retain intravenously administered triiodothyronine, by mechanisms susceptible to saturation with excess triiodothyronine. A neuroregulatory role for thyroid hormones, strongly supported by the observations, may account for their marked effects on behavior and the activity of the autonomic nervous system.

High-speed electron microscope autoradiographic studies of diffusible compounds

Three important factors are necessary for successful electron microscope autoradiography (EM-ARG): good resolution, proper preparation of the radioactive isotope (RI) labeled diffusible compounds, and shortened exposure time for ARG. The resolution problem is fundamental to EM-ARG. However, unless the diffusible RI compounds have been fixed correctly in the tissues during preparation, good resolution is useless. It is also necessary to shorten the exposure time for ARG. As yet, a high-speed ARG method fol electron microscopy has not been reported, although scintillation ARG methods have been applied to macro- and micro-ARG since 1960. High specific activity, a large amount of radioactivity per unit exposure for radio incorporation (incubation), and careful selection of labeled compounds that concentrate in the DNA or RNA of cell organelles may increase the sensitivity of the emulsion and shorten the exposure time for ARG. For example, labeled thymidine accumulates in nuclear DNA, 3H-SPG (Schizophyllan-produced polyglucan) is incorporated into lysosomal granules, and labeled iodine concentrates in thyroid follicles, often increasing the sensitivity of the emulsion and shortening the exposure time, but high-resolution ARG continues to be necessary, even though it requires 4 weeks or more of exposure time. Scintillation autoradiography using tritium seems unstable. We propose a new way to shorten exposure time for EM-ARG, by combining overdevelopment with coating both sides of the grid with emulsion. This method is approximately 100 times more sensitive than the conventional method, and only 4 days of exposure time are required, in contrast to the 1 month usually needed.

A structural and developmental study of adepidermal granules in the anuran tadpole using tannic acid fixation

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An analysis of the histochemical procedure for sodium ion detection

Some aspects of the histochemical technique for the detection of sodium ions with potassium antimonate have been analyzed. When potassium antimonate is used for the detection of sodium ions the pH should not decrease below 7.2 during fixation. Potassium antimonate was also precipitated by ethanol used for dehydration, resulting in dilution of the water used as solvent. This should not be confused with the histochemical product. Precipitate may be formed with calcium ions and magnesium ions. Potassium phosphate buffer used to control the pH seems to inhibit the precipitation reaction of potassium antimonate with sodium ions; the nonbuffered fixative produces a good result at the electron microscopic level.