In vivo observation of cell division of anaerobic hyperthermophiles by using a high-intensity dark-field microscope.

To study growth and cell division of anaerobic hyperthermophilic archaea in vivo, a cultivation technique using glass capillaries was developed. At temperatures of 90 to 98 degrees C, at least 10 successive cell divisions of Pyrodictium abyssi TAG 11 were documented. Cells divide by binary fission. Visualized under a modified dark-field microscope, the formation of cannulae, which finally connected all cells, was observed. The cannulae elongated at 1.0 to 1.5 micrometers/min and reached final lengths of between 30 and 150 micrometers. A "snapping division"-like mode of cell fission was discovered for Thermoproteus tenax.

Fertilization of bovine oocytes induced solely with combined laser microbeam and optical tweezers.

PURPOSE: Our purpose was to show that fertilization of oocytes can be obtained solely by laser light-mediated manipulation of gametes. METHOD: A small channel was drilled into the zona pellucida of bovine oocytes using an ultraviolet (UV)-laser microbeam. Highly diluted cattle sperm were not able to fertilize the laser drilled oocytes. RESULTS: Fertilization was achieved only when three to five cattle sperm were trapped with optical tweezers and inserted directly through the laser drilled hole into the perivitelline space. After 20 hr, 3 of 79 (3.8%) oocytes revealed two pronuclei and a sperm tail within their cytoplasm. Cattle sperm are difficult to catch. Therefore, the gametes had to remain for about 20 min in room atmosphere, which might be the reason for the low fertilization results. CONCLUSIONS: The results indicate that a combined UV-laser microbeam and optical tweezers trap can be used successfully for "noncontact" microinsemination procedures.

The surface layer of Mycoplasma mobile 163K and its possible relevance to cell cohesion and group motility.

Mycoplasma mobile strain 163K tends to move in multicellular configurations, either as pairs or small groups of three or more cells, or as chain-like aggregations or microcolonies. Such wandering groups arise by transient association of independently moving cells. This behaviour of M. mobile was microscopically investigated and documented by sequences of microcinematographic pictures, as well as by photomicrographically recorded motility tracks. The presence of an extracellular slime layer was demonstrated in thin sections, by negative staining and by scanning electron microscopy. The possible association of this layer with the cohesive properties of the mycoplasma cells, enabling the formation of wandering groups, is discussed and a calculation of the magnitude of the cohesive force is provided.

Application of the indirect enzyme immunoassay for the detection of antibodies against Erysipelothrix rhusiopathiae.

Sera from swine and rats experimentally infected with Erysipelothrix rhusiopathiae and field sera from swine were investigated for antibodies against E. rhusiopathiae using the microtiter enzyme immunoassay (EIA) and, for comparison, the growth test (GT) and the agglutination test (AT). In principle there was a good correspondence between the results of EIA and those of the two other methods, but EIA and GT were more sensitive than AT. On the basis of the evaluation pattern of GT and AT on swine sera, EIA titers of 1/320 were considered as "chronic erysipelas titers". Compared with GT and AT, the EIA has some advantages: it is not influenced by contamination of the test sera, it takes only a few hours and using the microtiter system it is easy and economical to perform.