[Electron microscopic detection and in situ characterization of bacterial nanoforms in extreme biotopes].

The morphology, ultrastructure, and quantity of bacterial nanoforms were studied in extreme biotopes: East Siberia permafrost soil (1-3 Ma old), petroleum-containing slimes (35 years old), and biofilms from subsurface oil pipelines. The morphology and ultrastructure of microbial cells in natural biotopes in situ were investigated by high-resolution transmission electron microscopy and various methods of sample preparation: ultrathin sectioning, cell replicas, and cryofractography. It was shown that the biotopes under study contained high numbers of bacterial nanoforms (29-43% of the total number of microorganisms) that could be assigned to ultramicrobacteria due to their size (diameter of < or =0.3 microm and volume of < or =0.014 microm3) and structural characteristics (the presence of the outer and cytoplasmic membranes, nucleoid, and cell wall, as well as their division patterns). Seven different morphostructural types of nanoforms of vegetative cells, as well as nanospores and cyst-like cells were described, potentially representing new species of ultramicrobacteria. In petroleum-containing slimes, a peculiar type of nanocells was discovered, gram-negative cells mostly 0.18-0.20 x 0.20-0.30 microm in size, forming spherical aggregates (microcolonies) of dividing cells in situ. The data obtained promoted the isolation of pure cultures of ultramicrobacteria from petroleum-containing slimes; they resembled the ultramicrobacterium observed in situ in their morphology and ultrastructure.

[Ultrastructural organization and development cycle of soil ultramicrobacteria belonging to the class Alphaproteobacteria].

Gram-negative chemoorganotrophic soil ultramicrobacteria (UMB), strains NF1 and NF3, have been isolated. In their development cycle, the strains formed small coccoid cells of 400-800 nm and ultrasmall cells of 200-300 nm. Phylogenetically, the strains NF1 and NF3 belong to Alphaproteobacteria and are close to the type strain of the recently described species Kaistia adipata. The ultrastructure of UMB cells has been studied using ultrathin sections and freeze-fracturing. It has been shown that the structure of UMB cell walls is of the gram-negative type; the outer membrane and peptidoglycan layer are well differentiated. The cell surface has numerous protrusions (prosthecae) of conical or spherical shape filled with the contents of the periplasm. The formation of unusual cellular structures (not occurring in known free-living bacteria) is a feature of UMB: these include the following: (a) piles of rod-like subunits, ca. 30 A in diameter and 150-250 angstroms in length: (b) long bunches (up to 300-400 angstroms) comprised of filamentous subunits; and (c) large electron-dense spherical bodies (up to 200-300 angstroms in diameter) localized in the periplasm. A distinctive feature of UMB is their ability to grow as facultative parasites on living cyanobacterial (CB) cells. In this case, three types of interaction between UMB and CB have been revealed: (1) adsorption of UMB cells on the surface of CB cells; (2) penetration of UMB into polysaccharide sheathes; and (3) penetration of UMB into CB eytoplasm. UMB cells have been shown to reproduce by budding, with buds (up to 2-3) located directly on the mother cell, without formation of intennediate hyphae.

[An electron microscopic study of the ultrastructure of microbial cells in extreme biotopes in situ]. / Elektronno-mikroskopicheskoe izuchenie ul'trastruktury mikrobnykh kletok in situ v ékstremal'nykh biotopakh.

The ultrastructure of microbial cells was studied in situ in natural biotopes by high-resolution transmission electron microscopy using the known methods of cryofractography, thin sectioning, and the negative staining of total cell specimens, as well as new methods of the low-temperature fractionation of microbial cells (providing for the recovery of cells from natural sources and their concentration), the preparation of micromonoliths, and aimed electron microscopy. Among the natural biotopes studied were permafrost ground and oil sludge. Most of the microorganisms found in the 1- to 3-million-year-old permafrost ground represented resting forms (spores, cysts, and cyst-like cells with specific organo-mineral envelopes). Oil sludge older than 35 years contained bacteria of atypical morphology and ultrastructure, including various resting forms and ultramicrobacteria. The data obtained is indicative of considerable promise of high-resolution electron microscopy in studying microbial communities in situ.

[The effect of ozone on the microbiological characteristics of the oral fluid in patients with mandibular fractures]. / Vliianie ozona na mikrobiologicheskie kharakteristiki rotovoi zhidkosti u bol'nykh s perelomami nizhnei cheliusti.

Thirty-nine patients with mandibular fractures were treated with ozonized solutions. Qualitative and quantitative characteristics of oral fluid were studied and correlated to clinical data.

[Action of hyperoxia on the total electrical activity of the olfactory epithelium of the frog]. / Deistvie giperoksii na summarnuiu élektricheskuiu aktivnost' oboniatel'nogo épiteliia liagushki.

Olfactory mucosa of the frog was stimulated with odours of amylacetat , butanol, alcohol, naphthalene, acetic acid in air and oxygen media under normal and high oxygen pressure (0.2 MPa and 0.7 MPa). The electroolfactogram (EOG) amplitude was higher in oxygen due, probably, to the olfactory mucosa oxygen saturation on concentration gradient as well as to the activation of processes related to the EOG generation. 0.2 MPa pressure as well as 0.7 MPa pressure applied for 60 min decreased the EOG amplitude.