Studies ofEuglena gracilisin aging cultures. I. Light microscopy and cytochemistry

The Cell Division Cycle of Euglena gracilis Indicates That the Level of Circadian Plasticity to the External Light Regime Changes in Prolonged-Stationary Cultures

“…We also observed multiheaded cells in 2-month-old cultures ( Supplementary Figure S2 ). These observations were consistent with a previous study of E. gracilis cell morphology in prolonged stationary phase [ 25 ]. Gomez et al [ 25 ] observed morphological changes from elongated cells during the log phase to spherical, enlarged, or clumping cells during the stationary phase after cultivation for 360 h.…”

“…Previous studies have reported that dark orange or reddish-brown to dark brown globules are commonly observed within Euglenida cells in aged cultures [ 25 , 26 ]. Consistent with this, we observed several brown globules within cells from 1- or 2-month-old cultures ( Figure 1 B; Supplementary Figure S2 ).…”

What is the role and nature of programmed cell death in phytoplankton ecology?

“…In this sense, algal senescence (see Table 1) could be functionally equivalent to multicellular plant senescence (which is controlled via PCD) with protease expression and cellular dissolution occurring in order to fulfil a functional role. One possible functional role of such a pathway in unicellular algae (and yeast) is to recycle the organic remains of cells for use by conspecifics (Gomez et al, 1974;Frohlich & Madeo, 2000). This idea is controversial and requires a convincing demonstration of conspecific nutritional (or other) benefit resulting from the cell death of some proportion of the cells (Franklin & Berges, 2004).…”

Senescence‐Related Changes in the Lipid Transition Temperature of Microsomal Membranes from Algae

“…Algal senescence studies are of interest not only because they provide a model system to study ageing, but also since any data obtained may aid in interpreting the dynamics of phytoplankton blooms and the role of algae as food material in the aquatic ecosystem. The production of ageing pigments in algae is well documented (Gomez et al 1974a), but changes in cellular function specifically attributable to senescence are less easily identifiable (Strehler and Barrows 1970). Gomez et al (1974a, b) in a study of Euglena graciiis observed cytochemical and ultrastructural changes with increasing age, while Daley and Brown (1973) correlated decreases in chlorophyll concentration and photosynthetic activity with the onset of declining growth in cultures of Anacystis nidulans and Phormidium molle.…”

“…The production of ageing pigments in algae is well documented (Gomez et al 1974a), but changes in cellular function specifically attributable to senescence are less easily identifiable (Strehler and Barrows 1970). Gomez et al (1974a, b) in a study of Euglena graciiis observed cytochemical and ultrastructural changes with increasing age, while Daley and Brown (1973) correlated decreases in chlorophyll concentration and photosynthetic activity with the onset of declining growth in cultures of Anacystis nidulans and Phormidium molle. These decreases continued during the stationary phase and were accompanied by ultrastructural deterioration.…”