Biology Reference
In-Depth Information
Figure 2:
Development of akinetes in
Anabaena planctonica
(A),
A
.
fl os-aquae
(B),
Anabaena
sp. (C) and
Gloeotrichia
sp. (D). The
magnifi cation bar in (D) represents 5 µm, in the rest it is 10 µm. Pictures (A) and (B) courtesy Mark T. Aubel, GreenWater
Laboratories/CyanoLab, 205, Zeagler Drive, Suite 302, Palatka, Florida 32177,USA. (http://www.greenwaterlab.com/
photo_algal.htm). Pictures (C) and (D) courtesy G. L. Tiwari, Department of Botany, University of Allahabad, Allahabad-
211002, India.
However, polyphosphate granules are reported to be absent (Wilden and Mercer, 1963; Leak and
Wilson, 1965; Miller and Lang, 1968; 1969; Jensen an Clark, 1969; Wildman
et al
., 1975; Sutherland
et al
., 1979; Grilli-Caiola and de-Vecchi, 1980). The thickened envelope of akinetes is composed of
polysaccharides and glycolipids (Cardemil and Wolk, 1981).
4) Biochemical composition
:
The envelopes of akinetes of
A
.
cylindrica
consist 41% of carbohydrate,
24% amino compounds and 1% lipids on a dry weight basis (Dunn and Wolk, 1970). The envelope
of akinetes of the same organism contained polysaccharides with subunits of glucose and mannose
linked by 1-3 β-glycosidic bonds (Cardemil and Wolk, 1976, 1979). Akinetes of
A
.
fertlissima
have
been shown to contain four glycolpids in contrast to fi ve glycolipids detected in vegetative cells
(Reddy, 1976). Many polar lipid components specifi c to akinetes of
A
.
torulosa
,
A
.
oscillarioides
,
Nostoc
calcicola
and
N
.
ellipsosporum
have been recognized.
A change in the pigment composition of akinetes has been reported by some workers (Fay,
1969a; Wolk and Simon, 1969). Mature akinetes of
A
.
cylindrica
revealed the absence of phycocyanin
with the replacement of chlorophyll by phaeophytin and a simultaneous decrease of β-carotene and
