Insect Pheromone Biochemistry And Molecular Biology Pdf
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- Russell A Jurenka | Department of Entomology
- Insect Pheromone Biochemistry and Molecular Biology
- Insect Pheromone Biochemistry and Molecular Biology - E-bog
- Insect Pheromone Biochemistry and Molecular Biology
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Russell A Jurenka | Department of Entomology
A biophysical model of receptor potential generation in the male moth olfactory receptor neuron is presented. It takes into account all pre-effector processes—the translocation of pheromone molecules from air to sensillum lymph, their deactivation and interaction with the receptors, and the G-protein and effector enzyme activation—and focuses on the main post-effector processes.
The evolution in time of these linked chemical species and currents and the resulting membrane potentials in response to single pulse stimulation of various intensities were simulated. The unknown parameter values were fitted by comparison to the amplitude and temporal characteristics rising and falling times of the experimentally measured receptor potential at various pheromone doses.
The model obtained captures the main features of the dose—response curves: the wide dynamic range of six decades with the same amplitudes as the experimental data, the short rising time, and the long falling time. It also reproduces the second messenger kinetics. Several testable predictions are proposed, and future developments are discussed. All sensory neurons transduce their natural stimulus, whether a molecule, a photon, or a mechanical force, in an electrical current flowing through their sensory membrane via similar molecular and ionic mechanisms.
Olfactory receptor neurons ORNs , whose stimuli are volatile molecules, are no exception, including one of the best known: the exquisitely sensitive ORNs of male moths that detect the sexual pheromone released by conspecific females. We provide a detailed computational model of the intracellular molecular mechanisms at work in this ORN type. We describe qualitatively and quantitatively how the initial event, the interaction of pheromone molecules with specialized receptors at the ORN surface, is amplified through a sequence of linked biochemical and electrical events into a whole cell response, the receptor potential.
We detail the respective roles of the upward activating reactions involving a cascade of ionic channels permeable to cations, chloride and potassium, their control by feedback inactivating mechanisms, and the central regulatory role of calcium. This computational model contributes to an integrated understanding of this signalling pathway, provides testable hypotheses, and suggests new experimental approaches. PLoS Comput Biol 5 3 : e This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. Olfactory receptor neurons ORNs are essential for the recognition of odor molecules.
In vertebrates this recognition is performed by several hundreds olfactory receptor proteins ORs borne by the ORN plasma membrane, each ORN expressing a single type of receptor . In insects a smaller number of ORs have been identified  — . In male moths, ORNs housed in antennal sensilla trichodea Figure 1 can detect female-released sexual pheromone with exquisite sensitivity, specificity and efficiency . These ORNs have been the subject of intensive studies during the last fifty years using molecular, radiochemical, pharmacological, electrophysiological, calcium imaging, behavioral and modeling techniques reviewed in  — .
The latter contribution has been significant and ORNs have experienced a rich history of modeling, since reports that a male moth can find a pheromone releasing female from several miles away  ,  and that a single pheromone molecule is sufficient to elicit an action potential in the moth sensory neurons . The system has been modeled at the level of behavior  ,  , at the level of antenna as biomechanical filter for odor molecules  —  , at the level of electrical circuits that give rise to action potentials e.
In fact this process consists of a biochemical network of the carrier proteins pheromone binding proteins, PBPs , ORs and odor degrading enzymes  ,  which occupy a common space surrounding the outer dendritic receptive membrane of ORNs. The sensillum is a small organ typically composed of 2 ORNs and 3 auxiliary cells thecogen Th, trichogen Tr and Tormogen To , housed within a porous cuticular hair. The tight junctions between cells separate the ORN extracellular environment in two parts with different ionic compositions, the sensillar lymph bathing the outer dendritic segment sensory and the hemolymph bathing the inner dendrite and soma.
In experimental conditions the pheromone is delivered close to the hair. The ORN electrical response is recorded extracellularly with an electrode slipped on the cut hair tip. Figures 2 and 3 give detailed views of the ORN membrane processes at the molecular level.
Figure 6 gives an overview of the global electrical organization of the sensillum. Modified from . A reasonably complete picture of the transduction processes emerges from these studies, although some of the molecular and ionic channel mechanisms underlying the transduction process still remain elusive.
This enzyme catalyzes the production of second messenger molecules, inositol 1,4,5-triphosphate IP 3 and diacylglycerol DAG , which trigger the opening of a cascade of various ionic channels. The resulting ionic currents generate the receptor potential RP which passively propagates to the ORN soma and axon where it generates action potentials.
Recently, this classical metabotropic mechanism has been challenged in insect ORNs and a direct coupling of the OR to a cationic channel has been proposed in parallel or in replacement  — .
These new developments are important from molecular, physiological and evolutionary points of view. The full description of such a complex signaling network, involving both feedforward and feedback processes, is a daunting task.
Modeling can contribute to this description by integrating various effects and displaying quantitatively what results from the interplay of all molecular actors. The knowledge accumulated on the pheromonal ORN is sufficient to start building a model of its transduction cascade, and to test whether it can effectively link together some of the known facts and suggest new experiments.
Thus, the first aim of our investigation was to develop a qualitative model of the pheromone transduction cascade integrating the known molecular and ionic mechanisms.
The second aim was to translate these mechanisms, wherever possible, into a set of differential equations and to determine the quantitative values of their parameters. We made a systematic search of known values and determined the unknown values by fitting the model output to the properties of the experimentally measured RP.
They offer the most precise data on the transduction cascade available so far. These responses are characterized by a rapid rising phase, a slow falling phase, especially at high concentrations, and an extremely wide dynamic range of about 6 decades from threshold to saturation.
In insects, most modeling efforts have been dedicated to the perireceptor and receptor processes in moth pheromone sensilla  ,  — . Although interactions of ORs, G-proteins and effectors have been recently studied  , no model has been proposed yet for post-effector processes in insects. The model we present here focuses on these processes in male moth pheromone ORNs and takes advantage of the modeling studies available on olfactory transduction in vertebrates  — .
Beyond fitting adequately the experimental dose-response curves we addressed the following related questions. What are the functional roles of the various currents? In particular, what could be the respective roles of the direct ionotropic and indirect metabotropic gating mechanisms of the initial cationic current? What are the mechanisms behind the characteristics of the concentration-response curves broad dynamic range, short rising time and long falling time?
What are the processes that contribute most to the amplifying function of the cascade? In the first three subsections a formal model of pheromone transduction is presented. In the next three subsections the model is fitted to experimental data and its properties are studied. Based on experimental results obtained in moth ORNs, complemented when necessary with data coming from other animal species and some reasonable assumptions, we developed a global qualitative model of pheromone transduction.
A schematic diagram of the model is shown in Figures 2 and 3. This model is summarized in this section. Some of the experimental results and the main assumptions denoted A to F on which it rests, are briefly mentioned and listed in Table 1. Complementary justifications, references and comments are provided in the Discussion section. In the present work, all these reactions were modeled as previously described . After adsorption on the cuticle the pheromone molecules enter the hair lumen through micropores in the sensillum wall.
They are also degraded by enzymes  , . These processes can be fundamentally viewed as two competing effects, one which is the entrance of molecules from the outside, corresponding to an uptake measured in micromole of pheromone per liter per second, and the other which is the degradation or hypothetic deactivation  of pheromone molecules.
When the system is stimulated by a square wave of pheromone, all pheromone molecules are not immediately removed so their concentration grows until there is an exact balance between uptake and removal. When stimulation ends, uptake returns to zero but removal continues until all pheromone molecules are removed and their concentration quickly falls to zero. This system, called flux detector by Kaissling  , would not work without removal because the pheromone molecules are trapped inside the perireceptor space.
The pheromone molecule binds to an OR step 3 then activates it step 4 , which presumably corresponds to a conformational change of the OR. The G-protein is involved in a loop which returns it to its initial state and the cycle can start again. The three proteins, R, G and E, can encounter one another and interact because they diffuse in the membrane.
Moreover, each activated OR can activate several G-proteins when it diffuses and so contributes to signal amplification. Generation of IP 3 induced by pheromones was found to be species- and tissue-specific; it occurs only in male antennae  , . The involvement of this enzyme in insect ORN responses was demonstrated by the fast and transient production of IP 3 after incubation of moth antennal homogenates with pheromone compounds  ,  ,  as well as with non-pheromonal odorants in locust and cockroach  , .
Its implication has also been demonstrated by a genetic approach in Drosophila . Upon application of pheromone, the concentration of IP 3 increases very rapidly reaching a maximum after about 50 ms, declines quickly to a lower plateau, then declines further with a slower time course to the basal level within a few hundred ms . IP 3 -dependent ionic channels were immunolocalized in the dendritic membrane of Bombyx mori and Antheraea pernyi ORNs .
First, DAG activates a non-specific cationic channel step 9. These DAG-gated cationic channels were observed in vivo from outer dendritic segments in A. The co-expression of OR83b with conventional ORs is necessary to get odor-evoked responses both in vivo and in vitro  , .
Both proteins interact with one another to form a heteromeric receptor complex . OR83b, alone  or heteromerized with the OR  , was recently identified as a cationic channel. First step 11 , in M. For this reason we did not include any feedback regulation of this current in the basic model. In antennal homogenates from A. The location of these channels is unknown. The qualitative description above, although indispensable, is not sufficient to gain a proper understanding of pheromone transduction.
We must now turn to a formal description of the various steps involved. Note that abbreviations in roman e. A formal description of the perireceptor and receptor stage steps 1 and 2,  ,  and the RGE stage steps 3 to 6,  were given previously and will not be repeated here. This system involves 13 chemical species and 12 reactions. It is described by a set of 13 ordinary differential equations and 4 conservation equations involving 17 parameters 4 initial protein concentrations, 10 reaction rate constants and 3 reaction rate constants limited by diffusion which are given as equations 12 — 28 in the Methods section.
Although very simplified, this model gives the same time-course of activated receptors as the more realistic model  and, likely, as the latest development of this model Kaissling, manuscript in preparation. The rest of this section is devoted to a formal description of the post-effector network of reactions involving diffusible modulators as well as ionic channels from which the evolution of the membrane potential can be derived.
These reactions are depicted schematically in Figure 3 and represented in standard biochemical notation in Figure 4. PA is phosphatidic acid. Reaction numbers same as in Figures 2 and 3. This is the only feedback-regulated reaction of the RGE stage in the model.
All reactions were modeled as standard bidirectional reactions, with a forward production and a backward degradation. Their expression as a set of first-order differential equations is straightforward, see equations 29 — 34 in Methods.
Insect Pheromone Biochemistry and Molecular Biology
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Insect Pheromone Biochemistry and Molecular Biology - E-bog
A valuable new reference on insect behavior, this exceptional new text delves into the primary sensory communication system used by most insects -- their sense of smell. Insect Pheromone Biochemistry and Molecular Biology covers how insects produce pheromones and how they detect pheromones and plant volatiles. Since insects rely on pheromone detection for both feeding and breeding, a better understanding of insect olfaction and pheromone biosynthesis could help curb the behavior of pests without the use of harmful pesticides and even help to reduce the socio-economic impacts associated to human-insect interactions. Chemical ecologists, neurobiologists, biologists, chemists, physiologists, entomologists, biochemists, and, molecular biologists. Biology and ultrastructure of sex pheromone producing tissue.
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A biophysical model of receptor potential generation in the male moth olfactory receptor neuron is presented. It takes into account all pre-effector processes—the translocation of pheromone molecules from air to sensillum lymph, their deactivation and interaction with the receptors, and the G-protein and effector enzyme activation—and focuses on the main post-effector processes. The evolution in time of these linked chemical species and currents and the resulting membrane potentials in response to single pulse stimulation of various intensities were simulated.
Insect Pheromone Biochemistry and Molecular Biology
From to , he served as the Chair of the Department of Biochemistry and Molecular Biology at this institution. He has contributed to hundreds of journal articles and book chapters on insect pheromones and biochemistry. Biology and ultrastructure of sex pheromone producing tissue. Biochemistry of female moth sex pheromones. Biosynthesis and endocrine regulation of pheromone production in Coleoptera.
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Insect Pheromone Biochemistry and Molecular Biology, Second Edition, provides an updated and comprehensive review of the biochemistry and molecular biology of insect pheromone biosynthesis and reception. The book ties together historical information with recent discoveries, provides the reader with the current state of the field, and suggests where future research is headed. Written by international experts, many of whom pioneered studies on insect pheromone production and reception, this release updates the first edition with an emphasis on recent advances in the field. This book will be an important resource for entomologists and molecular biologists studying all areas of insect communication. Researchers and practitioners in insect physiology, biochemistry and molecular biology entomology, or chemical ecology.
Home People Research Publications Positions. Insect Biochemistry and Molecular Biology DOI: Expansions of key protein families in the German cockroach highlight themolecular basis of its remarkable success as a global indoor pest.
Insect Pheromone Biochemistry and Molecular Biology, Second Edition, provides an updated and comprehensive review of the biochemistry and molecular biology of insect pheromone biosynthesis and reception. The book ties together historical information with recent discoveries, provides the reader with the current state of the field, and suggests where future research is headed. Written by international experts, many of whom pioneered studies on insect pheromone production and reception, this release updates the first edition with an emphasis on recent advances in the field. This book will be an important resource for entomologists and molecular biologists studying all areas of insect communication.