Expression map of a complete set of gustatory receptor genes in chemosensory organs of \u3cem\u3eBombyx mori\u3c/em\u3e

Most lepidopteran species are herbivores, and interaction with host plants affects their gene expression and behavior as well as their genome evolution. Gustatory receptors (Grs) are expected to mediate host plant selection, feeding, oviposition and courtship behavior. However, due to their high diversity, sequence divergence and extremely low level of expression it has been difficult to identify precisely a complete set of Grs in Lepidoptera. By manual annotation and BAC sequencing, we improved annotation of 43 gene sequences compared with previously reported Grs in the most studied lepidopteran model, the silkworm, Bombyx mori, and identified 7 new tandem copies of BmGr30 on chromosome 7, bringing the total number of BmGrs to 76. Among these, we mapped 68 genes to chromosomes in a newly constructed chromosome distribution map and 8 genes to scaffolds; we also found new evidence for large clusters of BmGrs, especially from the bitter receptor family. RNA-seq analysis of diverse BmGr expression patterns in chemosensory organs of larvae and adults enabled us to draw a precise organ specific map of BmGr expression. Interestingly, most of the clustered genes were expressed in the same tissues and more than half of the genes were expressed in larval maxillae, larval thoracic legs and adult legs. For example, BmGr63 showed high expression levels in all organs in both larval and adult stages. By contrast, some genes showed expression limited to specific developmental stages or organs and tissues. BmGr19 was highly expressed in larval chemosensory organs (especially antennae and thoracic legs), the single exon genes BmGr53 and BmGr67, were expressed exclusively in larval tissues, the BmGr27–BmGr31 gene cluster on chr7 displayed a high expression level limited to adult legs and the candidate CO2 receptor BmGr2 was highly expressed in adult antennae, where few other Grs were expressed. Transcriptional analysis of the Grs in B. mori provides a valuable new reference for finding genes involved in plant-insect interactions in Lepidoptera and establishing correlations between these genes and vital insect behaviors like host plant selection and courtship for mating

Electrophysiological and Morphological Characterization of Contact Chemosensilla in Adults and Larvae of the Butterfly, <i>Atrophaneura alcinous</i>

Distribution and electrophysiological responses of contact chemosensilla were examined in the Aristolochiaceae-feeding butterfly Atrophaneuraalcinous. In adult butterflies, tarsal contact chemosensilla of the foreleg were classified into two groups based on length: long- and short-type sensilla. Long-type sensilla were distributed much more widely in females than in males, whereas short-type sensilla were found at the edge of the tarsi in a similar manner in both sexes. Taste responses of the long- and short-type sensilla to methanol extracts of Aristolochia debilis and Citrus spp. were recorded. Aristolochia debilis extracts evoked spikes with different amplitudes, whereas Citrus spp. extracts evoked spikes with a single amplitude in the long-type sensilla. Short-type sensilla did not respond to either extract. Moreover, we recorded responses to different concentrations of sucrose and NaCl. Results suggest that adult butterflies can discriminate the taste of host plant components from other chemicals using long-type sensilla during oviposition and may recognize diets containing sugar and salts during feeding using short-type sensilla. In the larval mouthparts, there were lateral and medial styloconic sensilla on the maxillary galea and epipharyngeal sensillum on the epipharynx. Electrophysiological responses of these sensilla suggest that larvae can discriminate between host plant compounds

An oviposition stimulant binding protein in a butterfly <subtitle>Immunohistochemical localization and electrophysiological responses to plant compounds</subtitle>

Oviposition is evoked by plant compounds, which are recognized by chemoreceptive organs of insects. The swallowtail butterfly, Atrophaneura alcinous, oviposits its eggs on the host plant, Aristolochia debilis, in the presence of only two stimulating compounds: an alkaloid, aristolochic acid, and a monosaccharide, sequoyitol. In our previous study, a unique protein of 23 kDa [Oviposition stimulant(s) binding protein (OSBP)] was found in the forelegs of female, but not male, A. alcinous. The electrophysiological response of A. alcinous to an extract of A. debilis was depressed by the presence of OSBP antiserum, suggesting that OSBP presumably binds to oviposition stimulant(s). We show here, using a highly sensitive fluorescence micro-binding assay that native OSBP binds to a main oviposition stimulant, aristolochic acid, from its host plant, A. debilis. Three-dimensional molecular modeling studies also gave a reasonable structure for the OSBP / aristolochic acid complex. This is the first report of a native chemoreceptive protein binding to an oviposition stimulant ligand in insects

Tolerance to fermentation products in sugar reception: gustatory adaptation of adult butterfly proboscis for feeding on rotting foods

Adult Vanessa indica and Argyreus hyperbius frequently forage on flower nectar, but the former also utilizes tree sap and rotting fruits. Compared to flower nectar, these rotting foods are characterized by low sugar concentrations and the presence of fermentation products (ethanol and acetic acid). We suspected that gustatory responses by the receptors on the proboscis might differ in these species. Among the three sugars tested, sucrose elicited the greatest probing (behavioral) responses and was followed by fructose and glucose. A. hyperbius showed higher sugar sensitivity than V. indica in probing responsiveness. In electrophysiological responses of the proboscis sensilla, V. indica was slightly more sensitive than A. hyperbius to glucose and lower concentrations of the other sugars. The sugar reception in A. hyperbius was strongly inhibited by fermentation products, particularly acetic acid at natural concentrations. In contrast, V. indica was noticeably less susceptible to them than A. hyperbius, and its behavioral and sensory responses to sucrose were enhanced by 5–20% (w/v) ethanol. Thus, V. indica not only possesses tolerance to fermentation products but may perceive them as synergists for sugar reception. To utilize rotting foods, such tolerance might be more necessary than high sugar sensitivity

VCHP-ORC power generation from low-grade industrial waste heat combined with solar water heating system: Power generation and CO2 emission in industrial estate of Thailand

In the view of the total energy consumption by economic sectors of Thailand, it was shown that the greatest energy consumption derived from the industrial sector, where consumed both thermal energy and electrical energy for the processes. In this study, a novel concept of Organic Rankine Cycle (ORC) power generation is proposed. The power is generated from a low-grade industrial waste heat (IWH) with temperature below 70°C. The system is also combined with a solar water heating system (SWHS) and a vapor compression heat pump (VCHP) as a heating booster. A 400 kW thermal capacity VCHP, with R365mfc as the working fluid, is used to rise the heat from IWH and SWHS before supplying to a 60 kWe ORC power generator with R245fa. Three types of solar collectors were used to generate heat: flat-plate, heat pipe evacuated-tube and compound parabolic concentrator (CPC). Between 300 and 700 units of each type of the collectors were connected in parallel with $F_{\text{R}} \left( {\tau \alpha } \right)_{e}$ of 0.740, 0.572, 0.718, FRUL of 3.620, 0.750, 0.974 W/m2-K, and gross area of 2.081, 2.369, 2.160 m2 per unit, respectively. The system is designed to produces 10 m3/day of hot water at 70°C. The system is mathematically modeled and simulated to evaluate the net power output, the CO2 emission, and the levelized cost of electricity (LCOE). Six areas of industrial estate consisting of, Chiang Mai (18.80°N, 98.98°E), Bangkok (13.75°N, 100.52°E), Ratchaburi (13.54°N, 99.82°E), Songkhla (7.21°N, 100.56°E), Nakhon Ratchasima (13.75°N, 100.52°E), and Chon Buri (13.40°N, 101.00°E), that represent the north, central, west, south, north-east and east part of Thailand. Their weather data was taken for the simulations. The simulation results show that the system produces high electricity when the number of the collectors is increased. Moreover, the system located in Chiang Mai produced the highest amount of electricity with the lowest LCOE. When the temperature of low-grade IWH was around 64°C, with 700 solar collector units of each type of flat-plate, heat pipe evacuated-tube, and compound parabolic concentrator (CPC) solar collectors, the system can produce 84.4, 107.0, and 117.1 MWh/Year with LCOE of 0.35, 0.28, and 0.25 USD/kWh, respectively. In terms of the environmental impact, the system can reduce CO2 emission of 46.2, 58.6, and 64.2 Ton CO2 eq./Year, respectively. From this study, it can be concluded that the VCHP-ORC system can be integrated with the SWHS and used in industrial processes for power production as well as reduction of the energy intensity and CO2 emission of the industries