Further Observations on the Fine Structure of Chrysochromulina Minor and C. Kappa with Special Reference to the Pyrenoids

Abstract

Chrysochromulina minor and C. kappa have been re-investigated by means of electron microscopy of thin sections to add details of the microanatomy of pyrenoids and haptonemata, and by anoptral contrast light microscopy to study pyrenoids in living cells. In both species the pyrenoid is in the form of a diverticulum projecting from the centre of the inner face of a plastid and, in C. minor, strongly flexed to lie along it. In C. kappa the pyrenoid is commonly enveloped by the nucleus which may conceal it entirely from view in life. Some details of the behaviour of the surface membranes of plastids and pyrenoids in relation to that of the nucleus are given. The haptonema structure in both species is shown to be comparable to that of others in which this appendage is much longer, though an occasional variant with eight instead of seven central fibres or tubes has been encountered in C. kappa and is demonstrated. The presence of ‘peculiar’ Golgi structure is reported for both species and demonstrated for C. kappa. Some direct evidence indicating an internal origin of scales from vesicles is demonstrated in C. minor. Finally a summary is given of salient structural criteria for all the described species attributed to this genus from the marine plankton, the closest agreement as regards pyrenoid structure in the two species under investigation being with C. chiton.

A new non-toxic species in the dinoflagellate genusAzadinium:A. poporumsp. nov.

“…Thickness (and thus visibility) of this starch cup may in turn be quite variable. Moreover, the mode of pyrenoid distribution during cell division (pyrenoid longitudinal division, see Manton, 1966, or complete regeneration in daughter cells?) is poorly known.…”

Ribosomal DNA phylogenies and a morphological revision provide the basis for a revised taxonomy of the Prymnesiales (Haptophyta)

“…An organelle unique to haptophytes, termed the haptonema (Parke et al, 1955;Inouye & Kawachi, 1994), is located between the flagella. The haptonema differs structurally from the flagella, usually containing six or seven microtubules in the Prymnesiales, but sometimes eight as in Chrysochromulina kappa (Manton & Leedale, 1961a). The length of the haptonema varies greatly, from being many times the cell diameter in some species of Chrysochromulina (e.g.…”

“…The large Golgi body, in which scales are produced, lies anterior to the nucleus and just beneath the basal bodies, and is composed of a single fan-shaped dictyosome with many cisternae. The cisternae can be dilated, as in Chrysochromulina chiton (Manton, 1967a;Hibberd, 1976Hibberd, , 1980Pienaar & Birkhead, 1994).…”

Cytology and ultrastructure of the Xanthophyceae. II. The zoospore and vegetative cell of coccoid forms, with special reference toOphiocytium majusNaegeli

“…The characteristic position of the Golgi body, parabasal and lying against the anterior end of the nucleus, is also found in the Chrysophyceae and Phaeophyceae. This arrangement is different from that in the Haptophyceae where the single Golgi body, though parabasal, does not lie against the nucleus and is strongly polarised in the direction of the flagellar bases (Manton, 1967a(Manton, , 1967b. The condition of having a single parabasal Golgi body is never found in the remaining classes of algae.…”