![](bg5.png)
systems, we propose using a Petri net, initiated by
one or more input signals, computing a number of
pathways for the induction and reactivating phases.
In computer science bootstrapping refers to a
process where an initial system activates a more
constant system maintaining fundamental skill. The
initial process may be simple, activating a complex
system step by step. Activating metabolism in a
cryptobiotic organism may cause a chain reaction
that step by step brings back the organism to its
initial conditions. To model cryptobiosis both a Petri
net setting and a time based security model is used,
i.e. the chemical reactions involved and time for
accomplishing the involved tasks.
The input stress to which cryptobiotic organisms
are exposed could be seen as an “attack” against a
system. The organism must first detect the attack
and then respond to it in order to protect the system.
Organisms with a fast enough detection and
response will fulfil the protection mechanism’s
conditions. In a dynamic environment, where
varying environmental conditions are presupposed,
the robustness of the protection system may be
modelled. This robustness is dependent of the
strength of stress factor, possible threshold functions
connected Petri net pathways, detection time and the
success of all responses during a limited amount of
time.
Currently the biological phenomenon of
cryptobiosis lacks comprehensive models for
describing involved processes, both at a general
level and within more specific system. Such models
may be found within computer science. Petri net
settings may describe the different biological aspects
and processes connected with cryptobiosis, and
allow simulation of them. By putting more realism
into the models, a future progress of both models
and simulation tools may result in a better
understanding of resource control within protection
systems, an important issue both within life science
as within computer science.
REFERENCES
Alpert, P., 2005, The limits and frontiers of desiccation-
tolerant life. Integr. Comp. Biol. 45: 685-695.
Clegg, J.S., 1986, The physical properties and metabolic
status of Artemia cysts at low water contents: the "
Water Replacement Hypothesis". In: LEOPOLD, A.
C. (ed.) Membranes, Metabolism, and Dry Organisms,
pp. 169-187. Comstock Publ. Ass., London.
Clegg, J.S., 2001, Cryptobiosis – a peculiar state of
biological organization, Comp. Biochem. and Physiol.
Part.B. vol 128 (4).
Crowe, J.H., 1971,
Anhydrobiosis: an unsolved problem.
Am. Nat. 105: 563-573.
Crowe L.M., 2002, Lessons from nature: the role of sugars
in anhydrobiosis. Comp. Biochem. Physiol. A 131:
505-513.
Goyal, K., Walton, L.J., Browne, J.A., Burnell, A.M., and
Tunnacliffe, A., 2005, Molecular anhydrobiology:
identifying molecules implicated in invertebrate
anhydrobiosis. Integr. Comp. Biol. 45: 702-709.
Guidetti, R. and Jönsson, K.I.,, 2002, Long-term
anhydrobiotic survival in semi-terrestrial
micrometazoans. J. Zool. 257: 181-187.
Guppy, M., 2004, The biochemistry of metabolic
depression: a history of perceptions, Comp. Biochem.
and Physiol. Part.B. vol 139 (3).
Heiner, M., Koch, I. and Will J., 2004, Model validation
of biological pathways using Petri nets – demonstrated
for apoptosis. Biosystems 75 p. 15-28.
Keilin, D., 1959, The problem of anabiosis or latent life:
history and current concept. Proc. R. Soc. Lond. B.
150: 149-191.
Neuman; Y., 2004, Meaning making in the immune
system, Perspect. Biol. Med. 47.
Neuman, Y., 2006, Cryptobiosis: A new theoretical
perspective, Progress in Biophysics and Molecular
Biology 92.
Reddy,V.N., Mavrovouniotis, M.L., Liebman, M.N., 1993,
Petri net representation in metabolic pathways.,
Proceedings of the First International Conference on
Intelligent Systems for Molecular Biology, AAAI Press
p. 328-336.
Schill, R.O. Steinbruck, G.H.B., and Köhler, H-R, Stress
2004, gene (hsp70) sequences and quantitative
expression in Milensium tardigradum (Tardigrade)
during active and cryptobiotic stages, Journal of
Experimental Biology 207.
Schartau, W., 1999, Time based security. Practical and
Provable Methods to Protect Enterprise and
Infrastructure, Network and Nation, Interpact Press.
Watanabe, M., 2006, Anhydrobiosis in invertebrates. Appl.
Entomol. Zool. 41: 15-31.
Watanabe, M., Kikawada, T., Minagawa, N., Yokuhiro,
F., and Okuda, T., 2002 Mechanism allowing an insect
to survive complete dehydration and extreme
temperatures, J. Exp. Biol. 205: 2799-2802
Wharton, D., 1996, Water loss and morphological changes
during desiccation of the anhydrobiotic nematode
Ditylenchus dipsaci. J Exp Biol. 199: 1085-93.
Wright, J.C., 1989, Desiccation tolerance and and
waterretentive mechanisms in tardigrades. J. exp. Biol.
142: 267-292.
Wright, J.C., 2001, Cryptobiosis 300 years on from van
Leuwenhoek: what have we learned about tardigrades?
Zool. Anz. 240: 563-582.
DESCRIBING CRYPTOBIOSIS AS A TIME BASED PROTECTION SYSTEM USING PETRI NETS
285