Effects of Iron‐, Manganese‐, or Magnesium‐Deficiency on the Growth and Morphology of Euglena gracilis1

Abstract

Iron-, manganese-, or magnesium-deficiency has been induced in Euglena gracilis. Each arrests cell proliferation, decreases the intracellular content of the deficient metal, and increases that of several other metals. Light and electron microscopy of stationary phase cells reveal that Fe-deficient (-Fe) cells are similar in size and shape to control organisms. Magnesium-deficient (-Mg) cells, however, are larger, and approximately 14% are multilobed, containing 2 to 12 lobes of equal size emanating from a central region. Individual (-Mg) cells and each lobe of multilobed cells contain a single nucleus. Manganese-deficient (-Mn) organisms are morphologically more heterogeneous than (-Fe) or (-Mg) cells. Most are spherical and larger than controls. Approximately 15% are multilobed but, unlike (-Mg) cells, contain lobes of unequal size with either zero, one, or several nuclei present in each. Nuclei of (-Mn) cells differ in size and shape from those of control, (-Fe), or (-Mg) cells. All three deficient cell types accumulate large quantities of paramylon. Other cytoplasmic structures, however, appear normal. Addition of Fe, Mn, or Mg to the respective deficient stationary phase cultures reverses growth arrest and restores normal morphology. The results suggest that Fe-, Mn-, and Mg-deficiencies affect different stages of the E. gracilis cell cycle.

Growth response of the ichthyotoxic haptophyte, Prymnesium parvum Carter, to changes in sulfate and fluoride concentrations

“…In brackish waters of the southcentral USA where golden alga blooms have occurred, relatively high levels of SO 4 2- are typically accompanied by correspondingly high levels of hardness cations, including Mg 2+ [4,12]. Magnesium is a key micronutrient known to influence algal growth, lipid content and composition, and chlorophyll content [33,41–44]. Thus, the relatively high levels of Mg 2+ present in golden alga inland habitats may also serve to facilitate growth of this species.…”

Iron Deficiency Induces a Partial Inhibition of the Photosynthetic Electron Transport and a High Sensitivity to Light in the Diatom Phaeodactylum tricornutum

“…It is attributed to the inhibition of the chlorophyll (Chl) biosynthetic pathway, which requires the function of iron-containing enzymes ( van Leeuwe and Stefels, 1998 , 2007 ). Disconnection between light-harvesting centers as a consequence of ultrastructure changes of the thylakoid membranes under Fe-limited conditions ( Meisch et al, 1980 ; Terry and Abadía, 1986 ; Hilt et al, 1987 ) has been described as responsible for a decline of PSII efficiency, electron transport and carbon fixation ( Raven, 1990 ; Behrenfeld and Milligan, 2012 ; Petrou et al, 2014 ). Reduced photosynthetic efficiency due to loss of the D1 protein ( Greene et al, 1992 ), reduced concentration of Cyt b 6 f and Cyt c 6 and decreasing Cyt f :Chl a , P700:Chl a , and PSI:PSII ratios ( Greene et al, 1991 ; Allen et al, 2008 ) have been observed in Fe-limited continuous cultures of the diatom P. tricornutum .…”