PHEROMONES and EXOCRINE GLANDS IN ISOPTERA

Termites are eusocial insects that have a peculiar and intriguing system of communication using pheromones. The termite pheromones are composed of a blend of chemical substances and they coordinate different social interactions or activities, including foraging, building, mating, defense, and nestmate recognition. Some of these sociochemicals are volatile, spreading in the air, and others are contact pheromones, which are transmitted by trophallaxis and grooming. Among the termite semiochemicals, the most known are alarm, trail, sex pheromones, and hydrocarbons responsible for the recognition of nestmates. The sources of the pheromones are exocrine glands located all over the termite body. The principal exocrine structures considered pheromone-producing glands in Isoptera are the frontal, mandibular, salivary or labial, sternal, and tergal glands. The frontal gland is the source of alarm pheromone and defensive chemicals, but the mandibular secretions have been little studied and their function is not well established in Isoptera. The secretion of salivary glands involves numerous chemical compounds, some of them without pheromonal function. The worker saliva contains a phagostimulating pheromone and probably a building pheromone, while the salivary reservoir of some soldiers contains defensive chemicals. The sternal gland is the only source of trail-following pheromone, whereas sex pheromones are secreted by two glandular sources, the sternal and tergal glands. To date, the termite semiochemicals have indicated that few molecules are involved in their chemical communication, that is, the same compound may be secreted by different glands, different castes and species, and for different functions, depending on the concentration. In addition to the pheromonal parsimony, recent studies also indicate the occurrence of a synergic effect among the compounds involved in the chemical communication of Isoptera. (C) 2010 Elsevier B.V.

Sex-pairing pheromones and reproductive isolation in three sympatric Cornitermes species (Isoptera, Termitidae, Syntermitinae)

The species-specificity of pairing has been studied in three sympatric Neotropical termites: Cornitermes bequaerti, Cornitermes cumulans and Cornitermes silvestrii (Termitidae, Syntermitinae). Bioassays showed that sex attraction was highly species-specific between C. bequaerti and C cumulans but not between C. cumulans and C. silvestrii. The sex-pairing pheromone of the three species is secreted by the tergal glands of female alates. It consists of a common compound (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol. In C. bequaerti, this polyunsaturated alcohol is the only compound of the sex-pairing pheromone, whereas it is associated with the oxygenated sesquiterpene (E)-nerolidol in C. cumulans, and with (E)-nerolidol and (Z)-dodec-3-en-1-ol in C silvestrii. (3Z,6Z,8E)-Dodeca-3,6,8-trien-1-ol is responsible for sexual attraction, whereas (E)-nerolidol, which is inactive in eliciting attraction of male alates, is responsible for the species-specificity of the attraction. This is the first time that a multicomponent sex-pairing pheromone has been identified in termites. The role of (Z)-dodec-3-en-1-ol present on the surface of the tergal glands of the female alates of C. silvestrii could not be definitively determined, but it is suggested that this compound could be involved in the species-specificity of sex attraction with other sympatric species of Cornitermes. Our study shows that the reproductive isolation in termites is due to a succession of factors, as the chronology of dispersal flights, the species-specificity of sex-pairing pheromones and the species-specific recognition. (C) 2011 Elsevier Ltd. All rights reserved.

Identification of trail pheromone compounds from the labial glands of the stingless bee Geotrigona mombuca

Foragers of several species of stingless bees deposit pheromone spots in the vegetation to guide recruited nestmates to a rich food source. Recent studies have shown that Trigona and Scaptotrigona workers secrete these pheromones from their labial glands. An earlier report stated that species within the genus Geotrigona use citral from their mandibular glands for scent marking. Since convincing experimental proof for this conjecture is lacking, we studied the glandular origin of the trail pheromone of Geotrigona mombuca. In field bioassays, newly recruited bees were diverted by artificial scent trails that branched off from the natural scent trail deposited by their nestmates only when they were baited with extracts from the foragers` labial glands. Compounds extracted from the mandibular glands, however, did not release trail following behavior. This demonstrates that the trail pheromone of G. mombuca is produced in the labial glands, as in Trigona and Scaptotrigona. Furthermore, in chemical analyses citral was identified exclusively in the foragers` mandibular glands, which disproves its supposed role as a trail pheromone. The labial glands contained a series of terpene- and wax type esters, with farnesyl butanoate as major constituent. We, therefore, postulate that the trail pheromone of G. mombuca is composed of a blend of esters.

Trail-Pheromone Specificity of Two Sympatric Termites (Rhinotermitidae) from Southeastern Brazil

Studies on pheromone specificity are of ecological interest in termite biology where different species share the same habitat. In this work we evaluated the role of the trail pheromones as a mechanism for the isolation of sympatric populations of Coptotermes gestroi and Heterotermes tenuis (Rhinotermitidae) in Brazil. Based on our results, we conclude that trail pheromones are potentially capable of separating sympatric colonies of these species. Furthermore, the trail-pheromone specificity found in these species could be explained by quantitative differences of the common component of the trail pheromone. However, secondary components on the trail pheromone may neutralize the quantitative differences of a common component. Activity bioassays showed that synthetic (Z,Z,E) 3,6,8-dodecatrien-1-ol may act as the common component of the trail pheromone of these species. Further studies should focus on the chemical identification of the trails laid by the termites.

Identification of multi-component trail pheromones in the most evolutionarily derived termites, the Nasutitermitinae (Termitidae)

In the present study, trail pheromone blends are identified for the first time in termites. In the phylogenetically complex Nasutitermitinae, trail-following pheromones are composed of dodecatrienol and neocembrene, the proportions of which vary according to species, although neocembrene is always more abundant than dodecatrienol (by 25-250-fold). Depending on species, termites were more sensitive to dodecatrienol or to neocembrene but the association of both components always elicited significantly higher trail following, with a clear synergistic effect in most of the studied species. A third component, trinervitatriene, was identified in the sternal gland secretion of several species, but its function remains unknown. The secretion of trail pheromone blends appears to be an important step in the evolution of chemical communication in termites. The pheromone optimizes foraging, and promotes their ecological success. (C) 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 20-27.

Vision based context categorization for all-terrain robot

Dissertation presented at the Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa to obtain the Master degree in Electrical and Computer Engineering.

Dynamics of foraging and recruitment behavior in the Asian subterranean termite Coptotermes gestroi (Rhinotermitidae)

The present study investigated the trail-following behavior of the subterranean termite Coptotermes gestroi (Wasmann Rhinotermitidae) under laboratory conditions. The results showed that workers were the first to initiate the exploration to the food source. When food was discovered they returned to the nest laying a trail for recruiting nestmates to the food source. In this situation, workers always traveled significantly faster when returning from the arenas. Both workers and soldiers were recruited to the food source; however, the soldier/worker proportion was higher during the first phase of the recruitment. When no food was available, the number of recruited nestmates and the speed on their way back to the nest were significantly lower. The results also showed that scout foragers always laid trail pheromones when entering into unknown territories, and that chemical signals found in the food could induce workers of C. gestroi to increase their travel speed. Copyright © 2012 Alberto Arab et al.

Following the Connecticut trail from Delaware river to Susquehanna valley,

Bibliography: p. 179-181.

Pheromone paths attached to the substrate in meliponine bees: helpful but not obligatory for recruitment success

In contrast to marking of the location of resources or sexual partners using single-spot pheromone sources, pheromone paths attached to the substrate and assisting orientation are rarely found among flying organisms. However, they do exist in meliponine bees (Apidae, Apinae, Meliponini), commonly known as stingless bees, which represent a group of important pollinators in tropical forests. Worker bees of several Neotropical meliponine species, especially in the genus Scaptotrigona Moure 1942, deposit pheromone paths on substrates between highly profitable resources and their nest. In contrast to past results and claims, we find that these pheromone paths are not an indispensable condition for successful recruitment but rather a means to increase the success of recruiters in persuading their nestmates to forage food at a particular location. Our results are relevant to a speciation theory in scent path-laying meliponine bees, such as Scaptotrigona. In addition, the finding that pheromone path-laying bees are able to recruit to food locations even across barriers such as large bodies of water affects tropical pollination ecology and theories on the evolution of resource communication in insect societies with a flying worker caste.

Trail pheromones: an integrative view of their role in social insect colony organization.

Trail pheromones do more than simply guide social insect workers from point A to point B. Recent research has revealed additional ways in which they help to regulate colony foraging, often via positive and negative feedback processes that influence the exploitation of the different resources that a colony has knowledge of. Trail pheromones are often complementary or synergistic with other information sources, such as individual memory. Pheromone trails can be composed of two or more pheromones with different functions, and information may be embedded in the trail network geometry. These findings indicate remarkable sophistication in how trail pheromones are used to regulate colony-level behavior, and how trail pheromones are used and deployed at the individual level.

Reovirus-induced apoptosis is mediated by TRAIL.

Members of the tumor necrosis factor (TNF) receptor superfamily and their activating ligands transmit apoptotic signals in a variety of systems. We now show that the binding of TNF-related, apoptosis-inducing ligand (TRAIL) to its cellular receptors DR5 (TRAILR2) and DR4 (TRAILR1) mediates reovirus-induced apoptosis. Anti-TRAIL antibody and soluble TRAIL receptors block reovirus-induced apoptosis by preventing TRAIL-receptor binding. In addition, reovirus induces both TRAIL release and an increase in the expression of DR5 and DR4 in infected cells. Reovirus-induced apoptosis is also blocked following inhibition of the death receptor-associated, apoptosis-inducing molecules FADD (for FAS-associated death domain) and caspase 8. We propose that reovirus infection promotes apoptosis via the expression of DR5 and the release of TRAIL from infected cells. Virus-induced regulation of the TRAIL apoptotic pathway defines a novel mechanism for virus-induced apoptosis.

Designing pheromone communication in swarm robotics: Group foraging behavior mediated by chemical substance

In swarm robotics, communication among the robots is essential. Inspired by biological swarms using pheromones, we propose the use of chemical compounds to realize group foraging behavior in robot swarms. We designed a fully autonomous robot, and then created a swarm using ethanol as the trail pheromone allowing the robots to communicate with one another indirectly via pheromone trails. Our group recruitment and cooperative transport algorithms provide the robots with the required swarm behavior. We conducted both simulations and experiments with real robot swarms, and analyzed the data statistically to investigate any changes caused by pheromone communication in the performance of the swarm in solving foraging recruitment and cooperative transport tasks. The results show that the robots can communicate using pheromone trails, and that the improvement due to pheromone communication may be non-linear, depending on the size of the robot swarm.

Iowa's Mississippi River Trail Plan, 2003

The Mississippi River Trail (MRT) is a world-class bicycle trail that will follow the Mississippi River all the way from its headwaters in Minnesota to the Gulf of Mexico. The trail is partially completed; much of it is still in the planning and development stages. When complete, the MRT will Link over 2,000 miles of recreational trails through 10 states, including 280 miles in Iowa. Designated as a National Millennium Trail, the MRT will preserve natural environments along the river, stimulate economic growth in river communities, and provide bicyclists access to a variety of landscapes, history, and culture. The Iowa Department of Transportation commissioned the Center for Transportation Research and Education at Iowa State University to develop a plan for a safe, economically beneficial, and scenic MRT route through Iowa. This report presents the MRT plan for Iowa. It is organized in the following chapters: Executive Summary; (1) Introduction - vision statement and objectives; (2) Iowa MRT Minimum Design Standards; (3) Iowa MRT Route Analysis; (4) Recommended Improvement Plan; (5) MRT Implementation; and (6) Estimated Benefits and Impacts of the Iowa MRT. Additional information is provided in the following appendices: (A) GIS Analysis for the MRT; (B) Iowa MRT Maps; (C) Public Input; (D) Public Comments; and (E) References.

Methoxypyrazine removal in grape juice: Development of a removal system using odorant and pheromone binding proteins coupled with bentonite fining

Multicoloured Asian Lady Beetles (MALB) and 7-spot Lady Beetles that infect vineyards can secrete alkyl-methoxypyrazines when they are processed with the grapes, resulting in wines containing a taint. The main methoxypyrazine associated with this taint is 3-isopropyl-2-methoxypyrazine (IPMP). The wines are described as having aroma and flavours of peanut butter, peanut shells, asparagus and earthy which collectively, have become known as “ladybug taint”. To date, there are no known fining agents used commercially added to juice or wine that are effective in removing this taint. The goal of this project was to use previously identified proteins with an ability to bind to methoxypyrazines at low pH, and subsequently develop a binding assay to test the ability of these proteins to bind to and remove methoxypyrazines from grape juice. The piglet odorant binding protein (plOBP) and mouse major urinary protein (mMUP) were identified, cloned and expressed in the Pichia pastoris expression system. Protein expression was induced using methanol and the proteins were subsequently purified from the induction media using anion exchange chromatography. The purified proteins were freeze-dried and rehydrated prior to use in the methoxypyrazine removal assay. The expression and purification system resulted in yields of approximately 78% of purified plOBP and 62% of purified mMUP from expression to rehydration. Purified protein values were 87 mg of purified plOPB per litre of induction media and 19 mg of purified mMUP per litre of induction medium. In order to test the ability of the protein to bind to the MPs, an MP removal assay was developed. In the assay, the purified protein is incubated with either IPMP or 3-isobutyl-2-methoxypyrazine (IBMP) for two hours in either buffer or grape juice. Bentonite is then used to capture the protein-MP complex and the bentonite-protein-MP complex is then removed from solution by filtration. Residual MP is measured in solution following the MP removal assay and compared to that in the starting solution by Gas Chromatography Mass Spectrometry (GC/MS). GC/MS results indicated that the mMUP was capable of removing IBMP and IPMP from 300 ng/L in buffer pH 4.0, buffer pH 3.5 and Riesling Juice pH 3.5 down to the limit of quantification of the instrument, which is 6ng/L and 2ng/L for IBMP and IPMP, respectively. The results for the plOBP showed that although it could remove some IBMP, it was only approximately 50-70 ng/L more than bentonite treatment followed by filtration, resulting in approximately 100 ng/L of the MPs being left in solution. pIOBP was not able to remove IPMP in buffer pH 3.5 using this system above that removed by bentonite alone. As well, the pIOBP was not able to remove any additional MPs from Chardonnay juice pH 3.5 above that already removed by the bentonite and filtration alone. The mouse MUP was shown to be a better candidate protein for removal of MPs from juice using this system.

The transcription factor nuclear factor kappa B (NFkappaB) maintains TRAIL resistance in human pancreatic cancer cells

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL/Apo2L) is a member of the TNF family of cytokines that induces apoptosis in a variety of tumor cells while sparing normal cells. However, many human cancer cell lines display resistance to TRAIL-induced apoptosis and the mechanisms contributing to resistance remain controversial. Previous studies have demonstrated that the dimeric transcription factor Nuclear Factor kappa B (NFκB) is constitutively active in a majority of human pancreatic cancer cell lines and primary tumors, and although its role in tumor progression remains unclear it has been suggested that NFκB contributes to TRAIL resistance. Based on this, I examined the effects of NFκB inhibitors on TRAIL sensitivity in a panel of nine pancreatic cancer cell lines. I show here that inhibitors of NFκB, including two inhibitors of the proteasome (bortezomib (Velcade™, PS-341) and NPI-0052), a small molecule inhibitor of IKK (PS1145), and a novel synthetic diterpene NIK inhibitor (NPI-1342) reverse TRAIL resistance in pancreatic cancer cell lines. Further analysis revealed that the expression of the anti-apoptosic proteins BclXL and XIAP was significantly decreased following exposure to these inhibitors alone and in combination with TRAIL. Additionally, treatment with NPI0052 and TRAIL significantly reduced tumor burden relative to the control tumors in an L3.6pl orthotopic pancreatic xenograft model. This was associated with a significant decrease in proliferation and an increase in caspase 3 and 8 cleavage. Combination therapy employing PS1145 or NPI-1342 in combination with TRAIL also resulted in a significant reduction in tumor burden compared to either agent alone in a Panc1 orthotopic xenograft model. My studies show that combination therapy with inhibitors of NFκB alone and TRAIL is effective in pre-clinical models of pancreatic cancer and suggests that the approach should be evaluated in patients. ^