Green alga Euglena

Sublethal concentrations of zinc, cadmium and mercury in the culture medium inhibit both respiration and photosynthesis in the green alga Euglena (De Filippis et al., 1981 b). Photosynthesis probably is one of the most metal-sensitive processes of plant metabolism. In consequence, this aspect will be treated extensively. 

In-vivo metal application Reports of metal effects on electron transport and photophosphorylation after application of toxic amounts of metals to intact plants are less frequent. Cadmium and zinc inhibited PS 2 activity in Lycopersicon esculen-tum (Bazinsky et al, 1980) and Phaseolus vulgaris, respectively (Van Assche and Clijsters, 1983). In the green alga Euglena gracilis (De Filippis et al, 1981 b), PS 2 was sensitive to cadmium, copper and zinc. In the three species mentioned above, the water-splitting enzyme was the site of action. 

Cytochrome be has been purified to the electrophoretically homogeneous state by Stuart and Wasserman 24 )- This cytochrome is reduced by dithionite but not by ascorbate. The reduced form is autoxidizable and does not combine with CO. Its molecular weight was determined to be 40,000 on the basis of heme content. A similar cytochrome, showing the a band at 561-563 nm, has been observed in several species of green algae 203,242-251), Euglena 252,253), and red algae 254). 

A few respiratory type b cytochromes, which have an a band of around 562 nm but are distinct from photosynthetic cytochrome bt, have been reported to exist in Euglena and green algae (247,249, 6). 

The ferredoxin from the green alga Euglena has been isolated containing enriched Fe [28]. The two iron atoms appear to be identical, and in the oxidised Euglena ferredoxin give a quadrupole sphtting of 0-65 mm s at... 

Gibbs SP (1978) The chloroplast of Euglena may have evolved from symbiotic green alga. Can J Bot 56 2883-2889... 

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