Introduction to Fungi, Third Edition

678 ANAMORPHIC FUNGI
Fig 25.4 (a c) Arthrobotrys robusta.
(a) Conidiophores and conidia.
(b) Mycelium with anastomosing
traps. (c) Nematode caught in trap.
(d) Arthrobotrys oligospora.Two
conidiophores showing the sequence
of conidial development.
making up the ring is not simultaneous, but one
cell inflates a fraction of a second before the
others. By immersing rings in 0.3 0.5 M sucrose
and inducing trap closure by heat, Muller (1958)
succeeded in slowing down the rate of ring
closure by a factor of 100, so that the process
took about 10 s. Estimations of the volume
change of the cells during constriction showed
a threefold increase.
Several physiological changes must take place
during closure. Chen et al. (2001) have provided
evidence of a signalling chain in which a physical
stimulus at the inner ring surface activates a
trimeric G protein, and transduction of this
signal via inositol trisphosphate, Ca 2þ and
calmodulin (see Fig. 12.48) leads to the release
of osmotically active molecules within the ring
cells, coupled with the opening of water channels
at the plasma membrane surface. Muller
(1958) estimated that there must be an uptake of
18 000 mm 3 of water in 0.1 s, and water uptake
may therefore take place over much of the