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The Protozoa
Published in Donald L. Price, Procedure Manual for the Diagnosis of Intestinal Parasites, 2017
The classical form is readily recognized in human fecal preparations (see Plates 6, 41, 73, 84). It is highly refractile, usually has a large central area that appears similar to a vacuole which is surrounded by a thin layer of cytoplasm containing several light-staining nuclei and dark-staining volutin granules. The ameboid form also may be present in wet preparations but requires high contrast to differentiate it from other materials and it is rarely recognized in routine examinations of specimens.
Imaging the in vivo growth patterns of bacteria in human gut Microbiota
Published in Gut Microbes, 2021
Liyuan Lin, Jia Song, Jian Li, Xiaolei Zuo, Hong Wei, Chaoyong Yang, Wei Wang
Out of the 42 FISH labeling tested, we were able to identify 32 species with high selectivity, covering bacteria from nine families, with half-stained Gram-negative (Figure 2) and the other half stained Gram-positive bacteria (Figure 3). Gram-negative bacteria that belonged to the family Bacteroidaceae and Porphyromonadaceae were 1–2 μm rods, and showed relatively weak FDAA labeling due to their thinner PGN (Figure 2(a–j)). Some Gram-negative bacteria belonging to the Clostridium (Figure 2k-m) and Megamonas (Figure 2(n–p)) genus of the phylum Firmicutes, however, showed comparable FDAA labeling intensities with many Gram-positive bacteria. This leads to the speculation that these bacteria may possess Gram-positive-like PGN structures, even though they are normally stained as Gram-negative.13,14 The labeling patterns of the species belonging to the Clostridium genus (Figure 2(k–m)) were relatively similar, which divided in binary fission with a red septum in the middle of the bacteria. Megamonas (Figure 2(n–p)) bacteria were large rods with rounded ends, and the presence of volutin granules15 could be found in some species (Figure 2n). Furthermore, the labeling signals from the two FDAA probes were highly overlapped in these three species, indicative of their highly active growth and metabolism during the labeling process.