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Iraa prior experimental analysis of such information exchange between the feeding-inhibitory messenger menadione
(2-methyt-t ,4-naphthoquinone) from the environment, and sulthydryls in the dendritic membrane of chemosensitive neurons
in the antenna of Periplaneta americana, the electrochemical transduction of informational energy into organismal response
(i.e., activity) was described mathematically as a regression with r= 0.997 (Norris 1986, 1988). Thus, one unit of experimentally
determined input (stimulus) energy from the environment can be mapped (correlated) informationally upon (related to)
one unit of output (organismal-response) energy using the proposed sulfur-based encoding mechanism. Some key parameters
of this experimentally elucidated sulflaydryl / disulfide-dependent electrochemical mechanism are further discussed in Table
2.
Table 2.--Some key fascets of the sulfhydryl / disulfide-dependent electrochemical mechanism involved in insect perception
of phytochemical (e.g. 1,4-naphthoquinone) messengers.
1. Each of the three possible pairings of the chemoreception parameters (a, b, e) yields a linear regression with r > 0.95: (a)
the moles of messenger required in a standardized insect behavioral assay to cause a > 99% change in that behavior; (b) the
maximum in vitro polarographic U_/2shift in millivolts by the involved receptor and energy-transducer sulflaydryl / disulfide
protein from the insect's antennal chemosensory neurons when saturated with the above messenger: and (e) the maximum
percent inhibition of a standardized excitant-stimulated electroantannogram (EAG) by the above messenger (Rozental and
Norris 1973, 1975; Norris and Chu 1974; Norris 1979, 1986, 1988).
2. Simultaneous solution of the three linear relationships among the parameters in (1) showed that the correlation (rZ= 0.95)
between (a) the maximum U_/2shift elicited in the sulfhydryl / disulfide receptor and energy-transducer protein by the
messenger and (b) the maximum percent inhibition of the standardized EAG by that messenger is so high that only one of
these two parameters need be considered in a mathematical description of the transduction of the molar-messenger energy
into insect behavioral change. Log Y - 3.40 - 0.112 Log X, quantifies the energy-transduction relationship (Norris 1986,
11988).
3. Based on behavioral analyses (Rozental and Norris 1975; Norris 1986, 1988), three distinct sets of sulfhydryl (thiol)dependent
receptor sites for 2-methyl-1,4-naphthoquinone (menadione) messenger exist in the receptor and energy-transducing
protein in Periplaneta americana. Those sulfhydryls in each of these three sets of receptor sites cause a 4-5 millivolt
shift in the receptor and energy-transducing protein's U_/2value when they react at the mercury electrode involved in this
polarographic analysis (Rozental and Norris 1973; Norris 1979, 1986, 1988).
4. Based on the EAG-inhibition assay, messenger-menadione saturation of one set of receptor sites, as described in (3),
causes about an 8% inhibition (Norris and Chu 1974; Norris 1986, 1988). Thus, the theoretical maximal inhibition of the
standardized EAG by saturation of the receptors in all three sites with menadione might be predicted as 3 (sites) times 8%,
which equals 24%. It is interesting and significant that the experimentally determined range in maximal percent of EAG
inhibition by saturation with menadione was 23-25%.
5. Data summarized in (3) and (4) above lead to the interpretation that a receptor and energy-transducer Uz/2shift of 4-5 mV
equals an 8% inhibition in the EAG. This means that each 4-5 mV shift in the Uu2 is accompanied by an 8% inhibition in the
standardized EAG. The observed linear relationship between the U_a millivolt shift in the receptor and energy-transducer
protein and the percent EAG inhibition shows that the primary encoding of the message dictating the whole-insect behavior
occurs in the energy-transducer protein in the chemosensory sensillum (Norris 1979, 1986, 1988).
6. Our research explains for the first time, both in electrochemical and electrophysiological parameters, why the EAG is so
meaningful to an understanding of the chemical senses of insects. EAG does not just measure millivolts of electrical energy,
but also the energy after it has already been coded as information in the receptor and energy-transducer protein adequately to
elicit a predictable behavior in (by) the insect (Norris 1979, 1981, 1986, 1988).
7. Saturation of the receptor and energy-transducer protein with p-chloromercuribenzoate (PCMB), a compound which reacts
. specifically and irreversibly with sulfhydryls, blocks the above characterized messenger-induced Uu2 shift in the protein.
Thus, the conversion of molar-messenger energy into electrochemically based information adequate to predict whole-insect
behavior is blocked by the sulfhydryl-specific reagent, PCMB (Rozental and Norris 1973; Norris 1979, 1981, t988).
8. Sulfur, as in sulfhydryl / disulfide redox systems in proteins, is the critical dynamic elemental interface between responsive
cells and the stimulating environment, whether biotic or abiotic.
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