For
Online Viewing (412 K)
55. Brown, Jr. R. M. 1975. Pyrobotrys
gracilis (Volvocales) vegetative development. Encyclopaedia
Cinematographica. Film E 1678 des Inst. Wiss. Film Göttingen
Research Film 8:488-492.
55. General Remarks
Pyrobotrys gracilis
is a member of the Order Volvocales, Family Spondy-lomoraceae.
It is a colonial member, and is distinct from other members of
the Volvocales by the lack of a plakeal sequence in the divisions
leading to the formation of the daughter colony (SMITH [2]).
Pyrobotrys has mulberry-shaped colonies, and the cells
are alternately arranged in tiers of four cells each. The cells
are biflagellatte. The cells have a large cup-shaped chloroplast
lacking a pyrenoid, and a massive anterior stigma. The cells
are uninucleate. The Volvocaceae and the Spondylomoraceae have
been recognized as separate families on the basis of the mode
of formation of the daughter colonies. While the sequence of
daughter colony formation is well known with Volvocaoean algae
(e. g. Volvox) little attention had been paid to members
of the Spondylomoraceae. In 1989, VOSWINKEL [3] studied the life
history of Pyrobotrys at the light and electron microscopic
levels. During the course of this study Miss VOSWINKEL isolated
into axenic culture Strain TR-48 of Pyrobotrys. Subsequently,
her major professor, brought the alga to Freiburg, Germany in
1969 to study the phototactic responses. Because of the ease
in obtaining daughter colony formation, it was decided that it
would be useful to film this sequence, inasmuch as there are no
film records of daughter colony formation in the Spondylomoraceae,
and such information might be useful to phycologists in understanding
the rather complex life history of this interesting organism.
This short film documents the non-dividing colonial form of Pyrobotrys.
It follows the cleavage furrow pattern and establishment of new
daughter colonies from the parent cell.
Up to the 1975 Publications Page
Up to Malcolm Brown's Lab Page
Last modified 27 October 2005.
This document is maintained by Dr. R. Malcolm Brown, Jr.