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Study design: A case report of Neisseria sicca/subflava discitis in a healthy elderly female. Objective: To report a rare case, which is usually seen exclusively in children. Setting: Stoke on Trent, England. Method: Case report, a 65-year-old female with a 6 month history of back and bilateral leg pain. X-rays showed collapse of L4/5 disc. No neurological deficit. Magnetic resonance imaging supported the clinical suspicion of discitis. Percutaneous biopsy followed 2 weeks later by open biopsy with bilateral root decompression was performed. Culture of L4/5 disc tissue produced Neisseria sicca/subflava. The patient was treated with a 4-week course of intravenous amoxycillin. Follow-up at 3 months confirmed clinical resolution of original symptoms. Conclusion: Any organism cultured from biopsy needs to be interpreted within the context of the clinical case. If clinical suspicion is high, further weight must be added to the finding of unusual or environmental organisms and culture of a repeat aspirate or biopsy may clarify the significance.

The vesicular–arbuscular mycorrhizal fungus Glomus mosseae was examined by transmission electron microscopy and energy dispersive X-ray analysis. Electron-dense granules, found within vacuoles, were analyzed by X-ray analysis and found to contain high concentrations of phosphorus and calcium. These granules were similar in appearance to the polyphosphate granules described in other organisms. Highly vacuolated intercellular hyphae and vesicles possessed the greatest number of phosphorus granules. The granules were present in vacuolated arbuscular hyphae but absent from completely collapsed arbuscules. It was determined that the active arbuscule was the most probable site of breakdown of phosphorus granules. There were two other types of cellular inclusions, one vacuolar and one cytoplasmic, that could not be identified by X-ray analysis but that could easily be mistaken for phosphorus granules. It was concluded that general morphological appearance and location were not adequate criteria for the identification of phosphorus granules.

The ultrastructure of the interfacial zone which separates the intracellular structures of vesicular-arbuscular mycorrhizal fungi from host cytoplasm has been described in a variety of ways by recent investigators. Evidence is presented here which suggests that previous interpretations of the ultrastructure of the interfacial zone have been based on an artifact of fixation. Using an improved procedure, a dense, granular material was found in the interfacial zone. This material was preserved by simultaneous glutaraldehyde-osmium fixation but not by conventional prefixation and postfixation in glutaraldehyde and osmium, respectively.

Sclerotial germination, hyphal growth pattern, and appressorial formation of the charcoal rot fungus, Macrophomina phaseolina (Tassi) Goid. on the surface of soybean roots, Glycine max (L.) Merrill was observed using scanning electron microscopy. Sclerotial germination is followed by a hyphal growth pattern which does not appear to be associated with any specific structural feature on the corrugated root surface. Appressoria are produced on the root surface at the tips of both primary hyphae and side branches within three days after inoculation.

Procedures for sectioning fungal fructifications in host tissues or on artificial media are described, which allow observation of internal structures by scanning electron microscopy. Perithecia of Ceratocystis fimbriata and Phyllachora graminis, and telia of Puccinia xanthii showed excellent preservation of exposed structures in sections which were osmium-coated before being dried. While similar preservation was obtained in sectioned acervuli of Lecanosticta acicola and Marssonina juglandis and in pycnidia of Dothiorella ribis and Phomopsis occulta, the mucilaginous substances produced in these fructifications precluded observation of conidiophores. Extraction of mucilage from these sections was accomplished by periodic acid and dilute KOH treatments, followed by an osmium-coating procedure. In such preparations, mucilage was removed, internal structures were preserved, and pertinent characteristics of conidiogenous cells were resolved.

Phomopsis longicolla Hobbs, a causal agent of Phomopsis seed decay, colonizes the seed coats and embryos of mature soybean (Glycine max (L.) Merr.) seeds. The mode of infection of immature soybean pods and seeds by P. longicolla was examined using scanning electron microscopy. Phomopsis longicolla penetrated directly through pod walls by appressoria. Penetration through stomata in the pod surface was not observed. Immature seeds were also penetrated directly. Heavily infected immature seeds showed extensive colonization of the seed coats and embryos.

An ultrastructural investigation of seedling soybean root tissue infected by the charcoal rot fungus indicated that during the initial stages of pathogenesis, the fungus appears to be restricted mostly to the intercellular spaces and that penetration of interior cell walls occurred as a result of both mechanical pressure and chemical softening. Subsequently, the middle lamella disintegrates, the plasmalemma is separated from the cell wall, the cytoplasm becomes highly vesiculated and the mitochondria disorganized. In later stages of pathogenesis, the fungus becomes intracellular and recognizable cytoplasmic organelles disappear.

An intercellular matrix was observed to develop in normal cytoplasmic male-fertile corn lines infected by either race O or race T of Helminthosporium maydis. It usually occurred at the junction of necrotic and healthy cells but did not develop in infected Texas cytoplasmic male-sterile corn lines. Cytochemical tests indicated that the matrix was proteinaceous and ultrastructural examination showed that it was fibrous.

Mature conidia of race O and of race T of Helminthosporium maydis were examined microscopically to characterize the general ultrastructure of the conidia and to determine if the two races could be differentiated on the basis of conidial morphology. At the light-microscope level, the two races could not be separated. Histochemical analyses showed that, in both races, the cell wall was composed of chitin with melanin pigmentation. Electron-microscopic examination of thin-sectioned conidia revealed the presence of two distinct cell walls. Cross-walls were found to have typical ascomycetous septal pores. The types of cell organelles found in mature conidia did not provide any indication of the pathogenic capability of the fungus. No consistent differences were found in the ultrastructure of the two races and it was concluded that race T could not be differentiated from race O on the basis of conidial morphology.

Isolates of Phakopsora pachyrhizi from Australia, Indian, the Philippines, Taiwan, and Puerto Rico were compared with respect to morphology and development of 'Wayne' soybean. The most extensive comparisons were made between the Puerto Rican and Taiwanese isolates; these were indistinguishable in their prepenetration, penetration, and early colonization phases. Examination of uredia of all isolates by light and scanning electron microscopy (SEM) revealed no differences in uredial morphology. All isolates were indistinguishable with respect to uredospore size, shape, and apparently the number and distribution of uredospore germ pores. The only difference observed was the appearance of germ pores; germ pores of the Puerto Rican isolate were easier to see by means of SEM than those of the four Eastern Hemisphere isolates, suggesting that the Puerto Rican isolate may have thinner germ pore plugs. This difference is not sufficient to consider the isolates as taxonomically distinct.