Crateriform Structures Research Articles

The group of Macha craters in western Yakutia

The group of Macha impact craters in western Yakutia is represented by five crateriform structures from 60 to 300 m in diameter. The craters were formed in sandy strata of the Quaternary period and in underlying sedimentary rocks of Late Proterozoic ages. Shock metamorphic effects including planar features in quartz were established in the rocks from the craters. The age of the craters is 7315 ± 80 yr. The nature of the projectiles is not totally clear, although they might be iron meteoritic.

Isolation of a bacterium resembling Pirellula species from primary tissue culture of the giant tiger prawn (Penaeus monodon)

During attempts to establish tissue cultures from hepatopancreas, heart, and hemolymph of the giant tiger prawn (Penaeus monodon), using a medium including penicillin, streptomycin, and amphotericin B, bacterial contamination in the form of a sheet of growth attached to the tissue culture vessel was a persistent problem. Contaminant bacteria were teardrop-shaped cells arranged in rosettes, and electron microscopy revealed buds, crateriform structures, and the absence of a peptidoglycan layer in the cell wall, features characteristic of bacteria in the Planctomyces-Pirellula group, a phylogenetically distinct group of eubacteria. Two strains of contaminant bacteria were isolated in pure culture. Both exhibited morphology and antibiotic resistance consistent with their membership in the Planctomyces-Pirellula group (order Planctomycetales) of eubacteria. Tissue culture media for marine invertebrates may select for such bacteria if high concentrations of cell wall synthesis-inhibiting antibiotics are included.

Pirella marina sp. nov., a budding, peptidoglycan-less bacterium from brackish water

Summary Four new isolates of budding peptidoglycan-less eubacteria from brackish water of the Baltic Sea are described as Pirella marina. They are compared to Pirella staleyi, from which they can be differentiated by morphological characteristics such as the shape of buds and the distribution pattern of crateriform structures. They also differ in physiological characteristics for instance in their higher salt tolerance, requirement of NaCl for growth and use of a wider range of organic compounds as a carbon source.

Manganese and iron encrustations and other features ofPlanctomyces crassus Hortobágyi 1965, morphotype Ib of theBlastocaulis-Planctomyces group of budding and appendaged bacteria, examined by electron microscopy and X-ray micro-analysis

Water samples collected in August, 1980, from a pond in Budapest, Hungary, have permitted transmission and scanning electron microscopic observations to be made ofPlanctomyces crassus Hortobagyi 1965, which—to remain taxonomically noncommittal—we designated as morphotype Ib of theBlastocaulis-Planctomyces group of appendaged and budding bacteria. The detailed cell morphology of morphotype Ib (cellular shape, size and distribution pattern of crateriform structures, pili, spires) was similar to that of morphotype Ia,Planctomyces bekefii Gimesi 1924. The major appendage—a seemingly tubular, multifibrillar stalk—differed somewhat from the stalk of morphotype Ia, in that the morphotype Ib stalk was generally shorter than the morphotype Ia stalk, was tapered (the morphotype Ia stalk was uniformly cylindrical), and apparently lacked the organizing matrix of the morphotype Ia stalk. Energy-dispersive X-ray spectroscopy of the metallic-oxide encrustations of morphotype Ib rosettes revealed manganese and iron to be the predominant elements present. Moreover, localized differences were found in the relative amounts of the two elements deposited in different rosettes and at different loci on the same rosette.

Life cycle of a budding and appendaged bacterium belonging to morphotype IV of theBlastocaulis-Planctomyces group

The budding process of cell division in a bacterial strain (ICPB 4232) belonging to morphotype IV of theBlastocaulis-Planctomyces group was followed in aerobic slide cultures. Under the conditions employed, 3 h elapsed from the appearance of the earliest discernible stage of daughter cell formation to the separation of the mature ovoid bud. Budding invariably occurred at the broader pole of the ovoid, nonmotile mother cell. The separated daughter cell (bud), a motile swarmer, locomoted by means of an ensheathed flagellum attached at its broader pole. Approximately 30 h were required for the swarmer to develop into a sessile mother cell and initiate a new budding cycle. A mother cell was capable of producing an individual bud repeatedly at the same budding site. Transmission electron microscopy was employed to determine ultrastructural details regarding the single ensheathed flagellum, the polarly distributed crateriform structures and numerous pili, the excreted holdfast, the multifibrillar major appendage (a fascicle), and daughter cell (bud) formation.

Corniculate Cell surface protrusions in morphotype II of theBlastocaulis-Planctomyces group of budding and appendaged bacteria

Natural water samples and dilute-peptone enrichment cultures, containing budding and appendaged bacteria assigned to morphotype II of theBlastocaulis-Planctomyces group of nonprosthecately stalked prokaryotes, have been examined by transmission electron microscopy. When stained with 0.5% potassium phosphotungstate, the usual appendages of morphotype II (a flat, multifibrillar, ribbon-like stalk; peritrichous pili; and several cephalotrichous flagella) were observed, as were the crateriform structures found scattered over the surface of the cell. In 1.0% uranyl acetate stains, the crateriform structures were no longer visible; instead, unusual corniculate structures (“cornicula”) protruded at seemingly the same loci. These protrusions whowed a substructure, possibly in a helical arrangement. No definitive origin or function can yet be assigned to these cornicula.

Morphological diversity of freshwater bacteria belonging to theBlastocaulis-planctomyces group as observed in natural populations and enrichments

The nonprosthecate, stalked, budding, aquatic bacteria presently thought to belong to theBlastocaulis-Planctomyces group are morphologically quite diverse—as can be seen in high resolution transmission electron micrographs of these organisms as they occur in freshwater samples and enrichments prepared from them. Stalk fine structure is of several different types: some of these organisms possess flattened (in some cases, possibly tubular) ribbon-like stalks made up of parallel arrays of subunit fibrils of varying dimensions; others have stalks composed of twisted (ropelike) bundles of relatively coarse individual fibrils. Diversity exists in various other appendages (flagella, spires, fimbriae, holdfasts), cell envelope features (including the peculiar crateriform structures), degree of rosette formation, and cell shape. Based on this diversity, four morphotypes have been delineated among the members of this group. The axenic cultures we have isolated are being characterized within the morphotype framework.