Author(s)

N. MARCHETTINI, M. MARCHI, I. CORSI & E. TIEZZI,†

Abstract

True acetylcholinesterase (AChE), an important polymorphic enzyme of the nervous system, was studied to determine the inhibition of transmission of nerve impulses in muscles of the red swamp crayfish, Procambarus clarkii, exposed in vitro to organophosphate (OP) insecticides. The species showed moderate sensitivity to OP insecticides, confirming a factor of its invasive capacity in Mediterranean freshwater and brackish environments. The half maximal inhibition concentration (IC50, M) for AChE vs. acetylthiocholine activity (ASCh, 1 mM) in P. clarkii was compared with that of different tissues of various aquatic invertebrates recently described as invasive and with other non-invasive species. The results suggest that non-invasive species have a lower capacity than invaders to regulate transfer of nerve impulses across synapses, favoring an overall increase in their internal entropy. On the other hand, invasive species seem to have a high capacity to self-organize and produce negentropic internal processes, even though in many cases their strong adaptive capacity can be deleterious for the complexity and equilibrium of the community into which they are introduced, favoring an overall increase in entropy of the ecosystem. The internal complexity of the invasive species considered in this study is discussed in terms of evolutionary thermodynamics with particular emphasis on entropy production and related information.

Keywords

acetylcholinesterase activity, OP insecticides, entropy, complexity, biotic invasions, evolutionary thermodynamics