Polarization microscopy, possibly together with some contrast techniques (dark field and color phase contrast), was used to study the periphyton (microbiome) growing on filamentous green algae. The material containing filamentous algae with periphyton on the surface was collected in the villages of Sýkořice and Zbečno (Křivoklátsko Protected Landscape Area). The objects were studied in a LOMO MIN-8 St. Petersburg polarizing microscope and a Carl Zeiss Jena NfpK laboratory microscope equipped with an In Ph 160 basic body with variable dark field or color phase contrast and a Nikon D70 DSLR digital camera. Cells of filamentous algae of the genera Cladophora, Vaucheria, and Oedogonium were studied and the periphyton attached to them formed by cyanobacteria of the genera Chamaesiphon and Pleurocapsa and algae of the genera Characium, including diatoms of the genera Eunotia and Synedra. In all cases, the cell walls of the host algae showed a very strong birefringence. In contrast, the walls of cyanobacteria of the genera Chamaesiphon and Pleurocapsa were characterized by a much weaker birefringence (Pleurocapsa somewhat thicker), and the diatom frustules of the genera Eunotia and Synedra were almost without a birefringence. Strongly birefringent granules were found in the cytoplasm of the green alga of the genus Characium, which forms periphyton on the filamentous green algae of the genus Vaucheria. The periphyton on the filamentous alga of the genus Oedogonium, formed by cyanobacteria of the genus Pleurocapsa and diatoms of the genera Eunotia and Synedra, deposited in a massive layer of mucus containing birefringent crystals, showed a particularly strong birefringence. At the end of the vegetation of filamentous algae, their parts and remnants of periphyton (diatom frustules and crystals) became part of the detritus at the bottom of the culture vessel. The use of polarization microscopy in the study of filamentous algae with periphyton on the surface allows us not only to determine the birefringence of the observed structures, but also to partially deduce their chemical composition, or regular arrangement of particles, so-called shape birefringence.
A simultaneous application of negative phase contrast and polarization microscopy was used to study the internal structure of microbial cells. Negative phase contrast allowed us to display the fine cell structures with a refractive index of light approaching that of the environment, e.g., the cytoplasm, and converted an invisible phase image to a visible amplitude one. In the polarizing microscope, cross-polarizing filters, together with first-order quartz compensator and a turntable, showed maximum birefringence of individual structures. Material containing algae was collected in ponds in the villages Sýkořice and Zbečno (Protected Landscape Area Křivoklátsko). Objects were studied in a laboratory microscope (Carl Zeiss Jena, type NfpK), equipped with a basic body In Ph 160 with an exchangeable module Ph, LOMO St. Petersburg turntable mounted on a centering holder of our own construction and a Nikon D 70 digital SLR camera. Anisotropic granules were found only in the members of two orders of algae (Euglenales, Euglenophyceae and Chlorococcales, Chlorophyceae). They always showed strong birefringence and differed in both number and size. An important finding concerned thin pellicles in genus Euglena (Euglenales, Euglenophyceae) which exhibited weak birefringence. In genus Pediastrum (Chlorococcales, Chlorophyceae), these granules were found only in living coenobium cells. In contrast, dead coenobium cells contained many granules without birefringence-an important finding. Another important finding included birefringent lamellar structure of the transverse cell wall and weak birefringence of pyrenoids in filamentous algae of genus Spirogyra (Zygnematales, Conjugatophyceae). It was clearly displayed by the negative phase contrast and has not been documented by other methods. This method can also record the very weak birefringence of the frustule of a diatom of genus Pinnularia (Naviculales, Bacillariophyceae), which was further reinforced by the use of quartz compensator-an important finding. Simultaneous use of negative phase contrast and polarization microscopy allowed us to study not only birefringent granules of storage substances in microorganisms, but also the individual lamellae of the cell walls of filamentous algae and very thin frustule walls in diatoms. These can be visualized only by this contrast method, which provides a higher resolution (subjective opinion only) than other methods such as positive phase contrast or relief contrast.
- MeSH
- Anisotropy MeSH
- Cell Biology instrumentation MeSH
- Cell Wall chemistry MeSH
- Chlorophyta chemistry cytology MeSH
- Cytological Techniques methods MeSH
- Cytoplasm chemistry MeSH
- Birefringence MeSH
- Euglenida chemistry cytology MeSH
- Microscopy, Phase-Contrast * MeSH
- Microscopy, Polarization * MeSH
- Diatoms chemistry cytology MeSH
- Zygnematales chemistry cytology MeSH
- Publication type
- Journal Article MeSH
