We mounted a Nikon CoolPix 990 digital camera to a Zeiss Axioskop epifluorescence microscope
for both light and fluorescence microscopy. The camera was attached to the c-mount phototube
of the Axioskop by a metal sleeve. The metal sleeve fits over the standard Zeiss c-mount and
possesses a thread at the upper end that fits the lense threat of the CoolPix. The camera is
operated using a net adapter because the batteries' life time is too short for routine use of
the camera on the microscope. Microphotographs are usually taken at the highest camera photo
quality (Fine), but pictures posted here were taken at intermediate quality.
The coccoid cyanoabacterium Synechococcus spp. under green light excitation. The
phycoerythrin in the cells produces a deep red autofluorescence. Size of cells ca. 1.8 Ám.
Cells occur single or in doublets. Common phytoplankton in (sub)tropical oceans.
Size comparison between the coccoid cyanobacterium Synechococcus sp. (yellow),
heterotrophic bacteria (green), and Prochlorococcus sp. Prochlorococcus
does not contain phycoerythrin and exhibits a plain red autofluorescence. Bacteria
stained with SYBR Green I (Molecular Probes, Eugene, OR
What a grazer can eat -- This picture shows a heterotrophic organism that has ingested
several eukaryotic algal cells and heterotrophic bacteria. The outer cell membrane of the
grazer can be seen as a dim shadow (marked by stemless arrows; difficult to see on some
computer screen resolution and color settings.). The nucleus of the grazer
can be seen in dim green in the center of the cell, visible by SYBR Green I staining of the
DNA. SYBR Green I staining also produces green fluorescence in the bacteria. The orange cell
inside the grazer is probably not a Synechococcus but also a eukaryotic alga that is
already further digested. The chlorophyll autofluorescence of ingested algae is known to
turn to orange upon increasing chlorophyll digestion by the grazer cell. Some grazers retain
captured chloroplasts from ingested algae for a variable period of time and utilize the
photosynthesis these chloroplast can still perform. Such grazers are called mixotrophs, i.e.
their nutrition stems partly from ingesting other organisms and partly from the photosynthesis
of the retained chloroplasts.
The heterotrophic dinoflagellate Pfiesteria piscicida. Left: bright field microscopy,
Pfiestiera marked by black arrows, algal prey (the cryptomonad Rhodomonas)
marked by orange arrows. Right: Autofluorescence and DNA staining by YoYo-1 (Molecular
Probes, Eugene OR). The cell shape is seen by a faint green fluorescence; the nucleus (N)
is brightly stained by YoYo; ingested prey (the cryptomonad Rhodomonas) can be seen
inside the cell (Ch = prey chloroplast with red chlorophyll autofluorescence, N(P) = prey
nucleus, stained by YoYo).
Gram-staining of bacteria isolated on general nutrient agar plates for the Gulf Stream off
the South Florida coast. Long gram-positive rods in chains appear violet, gram-negative rods
red. 100× oil immersion objective.