Evidence of de novo synthesis of maltose excreted by the endosymbiotic Chlorella from Paramecium bursaria

Abstract

The endosymbiotic Chlorella sp. from Paramecium bursaria excretes maltose both in the light and in the dark. Experiments on photosynthetic (14)CO2 fixation and (14)CO2 pulse-chase experiments show that maltose is synthesized in the light directly from compounds of the Calvin cycle, whereas in the dark it results from starch degradation.

The taxonomy of green algae endosymbiotic in ciliates and a sponge

“…vacuoIata studied here compared with about 45% by the symbiotic Chlorella isolated from Paramecium bursaria (Table II). Excretion is pit-dependent in endosymbiotic Chlorella (Muscatine, Karakashian & Karakashian, 1967;Cernichiari, Muscatine & Smith, 1969;Reisser, 1981a;Ziesenisz, Reisser & Wiessner, 1981); besides sugars, amino acids also can be excreted at lower rates (Ziesenisz et at., 1981).…”

“…Excretion does not depend on any factors excreted by the host and continues to function after isolation of algae (Muscatine et al, 1967;Reisser, 1981a). The amount of excreted sugars is a "weak" characteristic since it depends on external pH (Cernichiari et al, 1969;Ziesenisz et al, 1981). Similarly, use of different carbon or nitrogen sources seems to be not so decisive for classification as formation of secondary carotenoids and hydrogenase activity (Kessler, 1982).…”

“…These prerequisites are now met for some of the most widespread members of the chlorophyceae living endosymbiotically, e.g. for those that are partners of freshwater ciliates (Reisser & Wiessner, 1984),…”

Maltose excretion by the symbiotic Chlorella of the heliozoan Acanthocystis turfacea

“…4) whereas they agreed in the symbiont from //yJ/Y/ (Cernichiari et al 1969). A nutritional difference is indicated by the ability of strain 3.83 to grow without added vitamins, whereas isolates from Paramecium require addition of vitamins Bi and B^ (Reisser 1975;Zieseniss et al 1981;Mucke 1985).…”

“…The influence of some physicochemical factors on this process has been investigated (Muscatine 1965;Cernichiari etal. 1969) and the origin of excreted maltose has been studied (Cernichiari et al 1969;Zieseniss et al 1981). Scanty data, however, exist on the possible active nature of the excretion process (Zieseniss 1982).…”