Zdeněk Žižka

Electron-microscope studies of Rickettsiella chironomi in the midge Camptochironomus tentans

Abstract The rickettsial etiology of a disease in the midge Camptochironomus tentans , was proved by electron microscopy of 25-year-old “type” material. Rickettsiella chironomi is an oval, flattened organism with a special system of cylindrical ridges covering its body in a layer beneath the covering or outer membrane. Other ultrastructures of the organism and of N-R-like bodies in infected tissues are described.

Airborne microorganism monitoring : a comparison of several methods, including a new direct counting technique

Samples of aerosol from the surrounding air were collected by forcing them to impact onto a solid nutrient medium, onto membrane filters, or onto microscope slides on microcover slips. The samples were cultivated or viewed in a fluorescence microscope by using a technique developed by us, or investigated by scanning electron microscopy. The amounts of microorganisms found by cultivation method, i.e. those forming microcolonies (CFU), were on average 85% lower than the amounts determined by the fluorescence technique. Cultivation of microorganisms trapped on Synpor filters of various pore size resulted in lower counts than conventional cultivation. Among bacteria, the genera Micrococcus, Bacillus and Corynebacterium predominated; the genera Neisseria, Actinomyces, Pseudomonas and others were also found. Of micromycetes, the genera Penicillium, Aspergillus and Cladosporium occurred most frequently in air. In the summer season, yeasts and other micromycetes prevailed, whereas in the winter season the bacteria counts were higher. The total counts of all components of the aeroplankton were higher in summer than in winter. Dust particles bounded mainly bacteria.

Fine structure of the neogregarine Farinocystis tribolii Weiser, 1953. Developmental stages in sporogony and parasite-host relations.

SummaryA description is given of the fine structure of the neogregarine Farinocystis tribolii in sporogony, and of parasite-host relations.After fusing of gametes a variable number of spherical zygotes are produced; there are usually eight, but their number may range from 3–10. The zygote is covered with a cytoplasmic membrane around which the wall of the oocyst develops. A large number of dark bodies and elongate mitochondria of the vesicular type are characteristic features of the cytoplasm of the zygote. The nucleus contains a promient osmiophilic nucleolus. In addition to developed zygotes, each gametocyst harbours a residual body with 2–7 nuclei, which autolyses later.During the period of spore formation from the zygotes we distinguished five sequential stages: a moderately ovoid stage, a navicular stage, an intensively staining stage, a uninucleate young spore (oocyst) and a mature spore with sporozoites. The fine structure of the moderately ovoid stage is similar to that of the zygote except that the wall of the former is thicker and both layers are undulate. The oocyst wall covering the navicular stages is deeply folded and thickened at the poles. Although the size of the dark included bodies did not change, they increased in number. The darkly staining stages are of irregular shape; they display a considerable affinity for iron haematoxylin, OsO4 and lead citrate. A staining layer deposited below the cytoplasmic membrane rises to the wall of the future spore. Typical of its cytoplasm was the presence of numerous canals and cisternae of endoplasmic reticulum. The wall of the uninucleate spore was thick, its cytoplasm condensed. There were plugs on both poles of the spore. Mature spores contained eight elongate sporozoites and a central cytoplasmic residual body without nuclei. There were no paranuclear bodies present in the cytoplasm of the sporozoites.At the start of infection, mitochondria of the host concentrate around schizonts and other immobile developmental stages of the parasite apparently as a kind of host response to the parasite. No other responses such as intensive phagocytosis or melanization were observed. After the consumption of the entire fat body of the host by the neogregarine only the nuclei of the fat cells remained in their original shape. The development of the host was stopped. If the infection is heavy the host dies.

Effect of increasing methanol concentrations on physiology and cytology ofCandida boidinii

Concentration of methanol in the medium strongly affected not only the physiology but also the cytology ofCandida boidinii strain 2 cells in a methanol-limited chemostat at a constant dilution rateD 0.1/h and at low pH 3.0. The formation of large cubic peroxisomes with high alcohol oxidase (AO) activity observed at low methanol concentration (S0 3 g/L) disappeared on increasing the methanol concentration in the inflow medium. The AO activity in the cells sharply decreased, followed by accumulation of riboflavin phosphate and residual methanol in the medium. The activity of catalase was relatively stable. At methanol concentrationS0>KI (K1 equal to 12 g methanol per L), which included a substantial increase in methanol dissimilation, documented by higher formaldehyde and formate dehydrogenase activities and by lower yield coefficient on methanol, the yeast cells contained large lobe-shaped peroxisomes and a smaller number of larger mitochondria. The cells formed pseudomycelium with a thick septum between the mother and daughter cells.

Examination of the cyst of Malamoeba locustae and of the spore of Mattesia dispora with the scanning microscope

Abstract The fine structure of the surface of cysts of the amoeba Malamoeba locustae and that of spores of the neogregarine Mattesia dispora have been examined with the scanning microscope. Freeze-drying was found to be the most convenient of the three methods tested for the preparation of the specimens. The surface of both mature and immature cysts of M. locustae is smooth, without a microrelief. By contrast, spores of M. dispora are equipped with a small, circular structure at the poles indicating the site of the future pore through which the sporozoites will emerge in the intestine of the new host. In addition, a flat relief forming small depressions is discernable on the surface of these spores at a high magnification.

The distribution of elements in cells of the methylotrophic yeast Candida boidinii as determined by electron probe X-ray microanalysis of ultrathin frozen-dried cryosections

Abstract The contents of sodium, magnesium, phosphorus, sulphur, chlorine, potassium and zinc in intracellular compartments of methylotrophic yeast Candida boidinii grown in a xylose-limited chemostat were determined by the method of electron probe X-ray microanalysis of ultrathin frozen-dried cryosections. The highest concentrations of sodium, magnesium, phosphorus, potassium and zinc were found in the vacuole, while the distribution of chlorine in the cells was nearly homogenous. Sulphur was absent in the vacuole while nearly all zinc present within the cell was localised in the vacuole.

Development of Amblyospora punctor sp.n. (Microspora: Amblyosporidae) in the Larval Mosquito Aedes punctor (Diptera: Culicidae)

Abstract A microsporidian infecting the fat body of last Aedes punctor larvae was found in Czechoslovakia. Only 2% of larvae in the spring population were visibly infected. Three periods are identified in the development of the pathogen: The pregamogonial merogony ending with formation of minute spherical garnets which fuse to binucleate zygotes. The period of macronuclear stages with meiotic divisions resulting in two presporonts, closed in a splitt-off plasmatic membrane together with granular secretion masses. A third period is that of sporogony starting with modeling fingerlike protrusions of future sporoblasts. The covering pansporoblastic membrane is the sphorophorous vesicle which is finally filled with eight broad oval spores measuring 6 × 7 µm. Their polar filament is anisofilar, the manubrial part in three coils and the thin flagellar part in 9 coils. Secretion masses were formed during the sporogony and resorbed during spore maturation.

Ultrastructure of the sporozoite and the sporocyst wall of the coccidian species Adelina triboliiBhatia, 1937 within the course of an autoinfection

Summary A description is given of the ultrastructure of the oocyst, the sporocyst and the sporozoite of the coccidian species Adelina tribolii, and of the development of the sporozoite in the original host, Tribolium castaneum (autoinfection). There are generally eight spherical sporocysts (10–13 μm in diameter) in the mature occyst. If the infection is heavy, the fat body of the host contains frequently broken and empty sporocysts. The wall of the sporocyst has three layers which change in their morphological appearace (undulation) after the rupture of the wall in its four, plate-like sutures. The wall of the sporocyst curls along its margins, and the sporocyst is invaded by the host cytoplasm and its nuclei. The sporozoite has two large, paranuclear bodies of a characteristic, crystalline structure which are surrounded by a layer of amylopectin-like granules. Sporozoites that have a conoidal complex are surrounded by a three-layered, cytoplasmic membrane. The sporozoite settles in the tissue and develops there in a trophozoite. The surface of the wall of its parasitophorous vacuole is extremely rough. As the trophozoite ages, the number of amylopectin-like granules increases, and that of micronemes decreases. The most persistent of the conoidal complex is its apical ring. Both the nucleus and the nucleolus of the trophozoite increase in size. The trophozoite changes in a schizont, its nucleus undergoes several divisions. The cortical layers of its cytoplasm have numerous, amylopectin-like granules.

Effect of metal ions on autofluorescence of the dry rot fungus Serpula lacrymans grown on spruce wood

This work describes autofluorescence of the mycelium of the dry rot fungus Serpula lacrymans grown on spruce wood blocks impregnated with various metals. Live mycelium, as opposed to dead mycelium, exhibited yellow autofluorescence upon blue excitation, blue fluorescence with ultraviolet (UV) excitation, orange-red and light-blue fluorescence with violet excitation, and red fluorescence with green excitation. Distinctive autofluorescence was observed in the fungal cell wall and in granula localized in the cytoplasm. In dead mycelium, the intensity of autofluorescence decreased and the signal was diffused throughout the cytoplasm. Metal treatment affected both the color and intensity of autofluorescence and also the morphology of the mycelium. The strongest yellow signal was observed with blue excitation in Cd-treated samples, in conjunction with increased branching and the formation of mycelial loops and protrusions. For the first time, we describe pink autofluorescence that was observed in Mn-, Zn-, and Cu-treated samples with UV, violet or. blue excitation. The lowest signals were obtained in Cu- and Fe-treated samples. Chitin, an important part of the fungal cell wall exhibited intensive primary fluorescence with UV, violet, blue, and green excitation.

Ultrastructural cytochemistry of Hansenula sp. cell wall

Abstract Polysaccharides were demonstrated in the cell wall of Hansemula sp., a methylotrophic yeast. A cytochemical method based on visualization of aldehydes, a product of oxidation by iodic acid of polysaccarides, was used as it has been proved to be the most specific in ultrastructural cytochemistry of polysaccharides (developed by Seligman, J. Histochem. Cytochem., 13, 629–639, 1965, and modified by Thiery, J. Microsc., Paris, 6, 987–1018, 1967). Two distinct layers of polysaccharides were visualized in the cell wall. The inner one contains higher concentration of polysaccharides. The concentration of polysaccharides is highest at junctions between two dividing yeast cells. Apart from polysaccharides detected in the cell wall itself, a layer exhibiting a weak staining for polysaccharides was detected around the cells as well.