Attachment Of Organisms Research Articles

Haemagglutinating and adhesive properties associated with the K99 antigen of bovine strains of Escherichia coli.

The K99 antigen common to some bovine strains of Escherichia coli caused mannose-resistant haemagglutination of sheep erythrocytes and was shown to be responsible for the attachment of K99-positive bacteria to calf brush-border preparations because (i) strains grown at 18 degrees C did not produce K99 antigen, cause haemagglutination, or attach to brush borders; (ii) a K12 (K99+) recombinant strain showed both haemagglutinating activity and attachment to brush borders whereas, before it received the K99 plasmid, the recipient strain was negative in both respects; and (iii) cell-free extracts of K99 antigen showed haemagglutinating activity and inhibited the attachment of K99-positive organisms to brush borders. K99 antigen appears to be a virulence determinant in the pathogenesis of neonatal calf diarrhoea. It is readily demonstrated by haemagglutination and brush-border attachment tests.

Interaction of Chlamydia trachomatis organisms and HeLa 229 cells

The infection of HeLa 229 cells in monolayer culture with trachoma (B/TW-5/OT) and lymphogranuloma venereum (LGV) (L2/434/Bu) organism was studied in terms of two parameters: radioactivity counts of cell-associated tritium labeled organisms at the initial stage of inoculation for measurement of attachment, and inclusion counts of infection cells after incubation for measurement of growth. Factors affecting attachment and inclusion formation and correlation of the two are presented. It was shown that attachment is an important initial step in infection by Chlamydia trachomatis. The rate of attachment was temperature dependent. The attachment of LGV organisms was affected more profoundly by temperature than was that of trachoma organisms. Attachment and inclusion formation of trachoma and LGV organisms were inhibited by heparin. Diethylaminoethyl-dextran was again shown to enhance attachment and inclusion formation of trachoma but not LGV organisms. NaF had no effect on attachment, but inhibited inclusion formation of both trachoma and LGV organisms. Both attachment and inclusion formation of trachoma organisms were strongly enhanced by centrifugation of the inoculum onto the cell monolayer. Although inclusion formation of trachoma organism was much greater in susceptible cells (HeLa 229) than relatively insusceptible cells (fetal tonsil), attachment was only slightly greater. The results based on the test of two cell lines suggested that attachment prpbably is not a critical factor in determing a cell line's susceptibility to infection with trachoma organisms.

GROWTH AND METABOLISM OF PERIPHYTIC BACTERIA: METHODOLOGY

Procedures for determining the growth rate and studying the metabolism of periphytic bacteria are presented. The number of unicellular bacteria or the aggregate length of bacterial filaments appearing on microscope slides after immersion in the habitat for varying lengths of time was determined by direct microscopy. To distinguish on the slides between in situ growth and passive attachment of organisms from the environment, germicidal ultraviolet radiation was used. A semimicro‐assay for amount of protein on colonized glass surfaces was developed. Growth curves based on protein determinations closely resembled those based on direct microscopic counts. Growth rates were determined in the Jordan River, Indiana, and in the effluent of Trinity Springs, a large cold‐water sulfur spring. Results obtained by direct microscopic counting and by protein assay were similar. Colonized glass surfaces were also used to demonstrate uptake of radioactive substrates by the periphytic flora.

Growth rate of Sphaerotilus in a thermally polluted environment.

In situ growth of Sphaerotilus on microscope slides immersed in a thermally polluted stream was studied. Ultraviolet radiation was used to differentiate between passive attachment of organisms from the water and growth of the organisms on the slides. Colonization of the slides in this environment took place solely by means of swarmer cells. A generation time of 2.3 hr was obtained at a water temperature of 18-22 C.

Growth Rate of Sphaerotilus in a Thermally Polluted Environment

In situ growth of Sphaerotilus on microscope slides immersed in a thermally polluted stream was studied. Ultraviolet radiation was used to differentiate between passive attachment of organisms from the water and growth of the organisms on the slides. Colonization of the slides in this environment took place solely by means of swarmer cells. A generation time of 2.3 hr was obtained at a water temperature of 18-22 C.

The Attachment of Protozoan Parasites to Intestinal Epithelial Cells of the Mouse

The attachment of a protozoan parasite believed to be Cryptosporidium parvum Tyzzer to intestinal epithelial cells in mice is described. At the attachment site the plasmalemma of epithelial cells is modified and becomes more pronounced as the development of the attachment organ of the parasite progresses. Although a reaction occurs in host cells in the form of accumulations of dense granules at the attachment region, no inflammatory reaction or hypercellularity in the lamina propria was observed. The parasites are usually enveloped by three membranous lamellae, each one having the characteristic unit membrane structure. The outer lamella is covered with a filamentous coating indistinguishable from that on epithelial cell microvilla. The origin of the coating on the parasites was not determined but there was evidence suggesting that the outer membranous lamella is continuous with the epithelial plasmalemma and that the parasite is, therefore, intracellular-a view contrary to prevailing opinion. In addition to several species of bacteria and fungi an impressive number of animal parasites have been demonstrated in the gastrointestinal tract of mice. Among the protozoans are several species of amebae, flagellates, and Received for publication 22 April 1966. * Supported in part by U. S. AEC Contract No. AT(11-1)-1244 and by U. S. Public Health Service Grant No. AM-06998. coccidia (Heston, 1956). Electron microscopic studies on the epithelial attachment of an organism believed to be Streptobacillus moniliformis in mice (Hampton, 1962; Hampton and Rosario, 1965) and probably of fungi in rats (Reimann, 1965) have been reported. In earlier publications primarily devoted to bacteria, cited above, the author reported the attachment of unidentified organisms and it was FIGURES 1-2. Cryptosporidium parvum (?) in intestine of mouse. Light micrographs illustrating attachment of different forms of the parasite (arrows) on the surfaces of villus epithelial cells. These were observed on villus tips and it looks as though the host cells are about to be extruded into the intestinal lumen. 1. Six small organisms which probably correspond to those shown in Figure 3. X 250. 2. Larger forms comparable to the stage shown in Figure 8. X 250.

Seasonal Distribution and Settling Rates of Estuarine Bryozoa

Records of the seasonal distribution and reproductive periods of the Bryozoa are sparse. Much of the available information is based on the finding of ovicelled specimens in dated collections; however, better information is to be had from the few test panel studies which include reports on the more common bryozoans of marine fouling communities. The latter method also permits analysis of larval settling rates and factors involved in the selection of attachment sites. Comprehensive reviews on the test panel studies have been presented by McDougall (1943) and the Woods Hole Oceanographic Institution (1952). Several factors have been found important in connection with bryozoan settling in seasonal studies. Visscher (1927) has demonstrated the importance of dark surfaces for collecting panels, Pomerat and Weiss (1946) have pointed out the effects of surface texture, while Pomerat and Reiner (1942) and McDougall (1943) have shown the influence of substrate angle and light on the attachment of sedentary organisms. The present paper deals with test surface studies on the Bryozoa specifically, utilizing a combination of the techniques of the above workers. It is the purpose of this study to report on the seasonal distribution, spatial distribution, reproductive periods and settling rates of estuarine bryozoans at Beaufort, North Carolina, with a consideration of environmental factors related to these. Other ecological observations on these species have been presented earlier (Maturo 1957). The writer wishes to express his sincere appreciation to Dr. I. E. Gray, under whose guidance this work was done. Thanks are also due to Dr. C. G. Bookhout for placing the many facilities of the Duke University Marine Laboratory at the writer's disposal, and to the U. S. Coast Guard and U. S. Army Corps of Engineers for permission to use permanent pile markers at investigation sites.