We previously described a remarkable type of cell motility that provided direct, visual evidence for the fluid nature of cell membranes. The movement involved continual, unidirectional rotation of one part of a protozoan, including the plasma membrane and cytoplasmic organelles, in relation to a neighbouring part. The cell membrane in the 'shear zone' appeared continuous with that of the rest o...

Heterotrophic flagellates often attach to surfaces while feeding. A possible fluid dynamic reason is that attachment increases filtration efficiency. This was investigated experimentally and theoretically. The effect of attachment on flow field and clearance was studied by video microscopy in the nanoflagellates Paraphysomonas vestita and Pteridomonas danica. The flow field around feeding cells...

In a previous study of ours, the superoxide scavenging activity of aqueous extracts from dinophycean red tide flagellates was detected by an electron spin resonance (ESR)-spin trapping method, but not by an L-012 (luminol analog)-dependent chemiluminescence (CL) method. To investigate the discrepancy between the two methods, the effect of ferric-protein complexes on superoxide scavenging activi...

The release of freshwater from the Mpofu Dam in November 1998 resulted in a short-term (6 d) longitudinal and vertical gradient of both salinity and nitrate in the estuary. There was no significant increase in phytoplankton chlorophyll a during the period of the study. The phytoplankton communities were dominated (> 10%) by diatoms and flagellates throughout the study. The average number of dia...

The diversity of free-living protozoa in five meat-cutting plants was determined. Light microscopy after enrichment culturing was combined with sequencing of PCR-amplified, denaturing gradient gel electrophoresis (DGGE)-separated 18S rRNA gene fragments, which was used as a fast screening method. The general results of the survey showed that a protozoan community of amoebae, ciliates, and flage...

In the microbial loop, organic matter, Irrespective of its origin and composition, is incorporated in the food chains only after it has been converted into bacterial biomass. The absence of polyunsaturated fatty acids (PUFAs) in bacteria leads to the loss of these components in the initial h k of the microbial loop. Thls results in significant differences in the nutritional value of the initial...

Attached to the basal bodies of Naegleria gruberi flagellates is a striated rootlet or rhizoplast. The rootlet-basal body complex has been isolated by Triton X-100 lysis of deflagellated cells and differential centrifugation through a 25% glycerol medium. Rootlets isolated from mature flagellates are approximately 13 micrometers long but vary from 8 to 15 micrometers in length: they taper at bo...

Phagotrophic protists are an important mortality factor of prokaryotes in most aquatic habitats. However, no study has assessed protistan grazing as loss factor of bacterial biomass across the stratification gradient of a temperate freshwater meromictic lake. Protistan grazing effect was quantified in the mixolimnion, the transition zone, and the sulfidic anoxic monimolimnion of Lake Alatsee (G...

Flagellates of Naegleria gruberi contain two calmodulins that differ in apparent molecular weight and intracellular location. Calmodulin-1, localized in flagella, has an apparent molecular weight of approximately 16,000, approximately the size of other protozoan calmodulins, whereas calmodulin-2, localized in cell bodies, is 15,300. Both proteins, purified, are calmodulins by several criteria, ...