Organisms have to constantly respond to environmental conditions to maintain a status of dynamic homeostasis for survival. As single celled organisms evolved into multicellular animals, intercellular and inter-organ communications became indispensable not only to orchestrate homeostasis but also to control the many events punctuating metazoan development. To accomplish this need, a signal transduction system was evolved, consisting of an arborized network of nerves as well as a collection of oligopeptide neurotransmitters (neuropeptides) along with their cognate receptors. We review here the current state of our understanding of the physiology of neuropeptides in the most species-rich group of animals, the crustaceans and insects. The vast majority of neuropeptides signal through cell-surface guanosine-protein coupled receptors (GPCRs). These neuropeptide-receptor systems control a variety of physiological functions, for instance the numerous involuntary movements of internal ducts that are precisely timed for transporting reproductive, digestive and secretory materials. The rigid exoskeleton in Crustaceans and Insects require periodic molts to accomplish growth and metamorphosis and this is harmoniously regulated by a cascade of neuropeptides. Neuropeptides also regulate various events in the life of organisms including biological clocks and behavior. Technological advances in peptidomics, through the routine use MALDI-TOF mass spectrometry and in genomics, with in silico identification of neuropeptide receptor genes have revealed a staggering diversity of extracellular peptide-based signaling systems. This diversity underscores that communication between the afferent (nervous) system and the appropriate organs for an efferent response must be done in an unambiguous manner without any short circuits or reversal of directions. While we have a broad understanding of how neuropeptides and their receptors play a vital role in signal transduction, much of the details remain to be unraveled.

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Earthworms are standard test organisms in soil toxicity testing. They have been broadly used to assess environmental impact from heavy metal pollution; however, the knowledge on toxic effects from pesticides upon these organisms is still very limited. One of the ecotoxicological approaches to assess pollutant bioavailability and sublethal effects is the use of molecular and biochemical biomarkers. This review focuses on five issues that need further investigation: 1) field validation of earthworm biomarkers of pesticide exposure (e.g., cholinesterases) as well as testing and development in earthworms of those biomarkers of pesticide exposure currently used in other organisms (e.g., carboxylesterases), 2) the impact of environmental and biological interfering factors upon biomarker responses, 3) the development of biomarker-based approaches to assess long-term pesticide exposure, and 4) the need to develop biomarkers of behavioural and reproductive disruption with direct implications at individual and population levels.

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Resistance of cotton aphid (Aphis gossypii Glover) collected from four leading cotton producing regions and one non-cotton producing region in Shandong Province, China, in 1985, 1999, and 2004 to fenvalerate, omethoate, imidacloprid, acetamiprid, carbosulfan, and endosulfan, was determined on cotton (Gossypium hirsutum L.). Dose-response results indicate that A. gossypii became highly resistant to fenvalerate, and the resistance ratios (RRs) increased from 30–370-fold in 1985 to 370–2150-fold from different regions as compared with the susceptible population (S). A. gossypii also exhibited strong resistance to imidacloprid and acetamiprid with RRs of 17- to 97-fold in 2004. Resistance of A. gossypii to omethoate varied greatly among the five geographical regions, and the RRs ranged from 5- to 80-fold. In contrast, the resistance to carbosulfan did not significantly increase from 1999 to 2004 in all regions. The information from this study would be helpful for management of A. gossypii on cotton in those regions.

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N-tert-Butyl-N,N '-diacylhydrazine (DAH) analogs are nonsteroidal ecdysone agonists. The binding activity of DAH analogs to the heterodimer of the ecdysone receptor (EcR) and ultraspiracle (USP) is diverse among insect species, which is probably the main factor causing their selective toxicity. We prepared EcR and USP proteins from lepidopteran Chilo suppressalis, dipteran Drosophila melanogaster and coleopteran Leptinotarsa decemlineata, and measured the binding activity of ecdysone agonists against various hybrid EcR/USP heterodimers. There was a linear relationship between binding activities (pIC₅₀ values) before and after replacing native USP with that derived from other insects, suggesting that the selective toxicity of DAH analogs is mainly dependent on the EcR structure and not the USP structure.

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We performed functional analysis of transgenic plants expressing the W548L/S627I mutated ALS gene from rice as well as studies on inheritance of the mutated gene, phenotype and fertility of transgenic plants to ensure availability of the mutated gene as a selectable marker for plant genetic transformation. Expression levels of the ALS (endogenous+mutated ALS) gene of transgenic rice plants were correlated with the resistance of transgenic plants to bispyribac-sodium (BS). The BS-resistant trait of a transgenic plant was stably inherited by the progeny in a Mendelian manner. A homozygote of transgenic plants harboring the mutated gene was normal in its growth and fertility compared with the wild type. These results ensured that the W548L/S627I mutated gene from rice can be efficiently used as a selectable marker for genetic transformation of rice in combination with BS.

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Metofluthrin [2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (1R,3R)-2,2-dimethyl-3-((1EZ)-prop-1-enyl)cyclopropanecarboxylate] was rapidly degraded in two aerobic US soils with first-order half-lives of 2.3–3.5 days primarily via ester cleavage to give the corresponding acid and alcohol without any epimerization and geometrical isomerization. The rapid oxidation proceeded either at the prop-1-enyl group of the acid to moiety form the diacid derivative or the benzyl carbon to finally give the terephthalic acid derivative. These metabolites were finally mineralized to carbon dioxide with partial formation of bound residues. The soil adsorption coefficients (K_oc) of the Z isomer, the main component of metofluthrin, in three German soils were determined to be 3553–6124 (ml/g o.c.) by the batch equilibrium method. The screening groundwater simulation model SCI-GROW using the metabolic half-lives and K_oc values clearly indicates that metofluthrin is most unlikely to contaminate groundwater even in the unrealistic worst case.

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A novel timed-release system with a certain lag time (or release-suppression time) of pesticides has been developed using coated water-swelling granules including a systemic insecticide. The lag time and release profile of the insecticide are controlled by the polymer composition of the membrane that contains low-density polyethylene (LDPE) and talc, and by the core granule composition of the water-swelling material.

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Right:See PDF for details.

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