P. Arancibia-avila et al., Carbonic anhydrase localization in charophycean green algae: Ecological and evolutionary significance, INT J PL SC, 162(1), 2001, pp. 127-135
Two carbonic anhydrase (CA) antibodies, one to the primarily periplasmic al
pha-type enzyme of the chlorophycean Chlamydomonas and another to pea (Pisu
m sativum) beta-type CA, which is primarily located in the chloroplast stro
ma, were applied to the charophycean green alga Mougeotia sp., shoot cells
of the later divergent charophycean, Chara zeylanica, and control Chlamydom
onas cells and pea leaf tissues. Immunolocalizations were quantitatively as
sessed at the ultrastructural level; nonimmune labeling was negligible in a
ll cases. The Chlamydomonas antibody intensely labeled inner cell wall, per
iplasmic region, and peripheral cytoplasm of Chlamydomonas, Mougeotia, and
Chara. The concentration of periplasmic label did not significantly differ
among these green algae. This is the first immunolocalization evidence for
occurrence of a periplasmic CA in Chara. Chloroplasts of Mougeotia, Chara,
and pea were also labeled by the Chlamydomonas antibody, suggesting that pl
ants inherited a plastid thylakoid-based, alpha-type CA from charophycean a
ncestors. The pea antibody labeled Chara chloroplasts but not those of Chla
mydomonas or Mougeotia. The concentration of pea antibody stromal label did
not significantly differ between pea and Chara. This is the first immunolo
calization evidence for occurrence of a higher-plant, beta-type stromal CA
in green algal plastids.