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Animals use a variety of sensory modalities-including visual, acoustic, and chemical-to sense their environment and interact with both conspecifics and other species. Such communication is especially critical in eusocial insects such as honey bees and ants, where cooperation is critical for survival and reproductive success. Various classes of chemoreceptors have been hypothesized to play essential roles in the origin and evolution of eusociality in ants, through their functional roles in pheromone detection that characterizes reproductive status and colony membership. To better understand the molecular mechanisms by which chemoreceptors regulate social behaviors, we investigated the roles of a critical class of chemoreceptors, the odorant receptors (ORs), from the ponerine ant Harpegnathos saltator in detecting cuticular hydrocarbon pheromones. In light of the massive OR expansion in ants (∼400 genes per species), a representative survey based on phylogenetic and transcriptomic criteria was carried out across discrete odorant receptor subfamilies. Responses to several classes of semiochemicals are described, including cuticular hydrocarbons and mandibular gland components that act as H. saltator pheromones, and a range of more traditional general odorants. When viewed through the prism of caste-specific OR enrichment and distinctive OR subfamily odorant response profiles, our findings suggest that whereas individual HsOrs appear to be narrowly tuned, there is no apparent segregation of tuning responses within any discrete HsOr subfamily. Instead, the HsOR gene family as a whole responds to a broad array of compounds, including both cuticular hydrocarbons and general odorants that are likely to mediate distinct behaviors.ant | odorant receptor | odor coding | pheromone T he detection of ecologically relevant chemosensory information is critical to the survival and propagation of all organisms. For example, sex pheromones allow members of the same species to locate and assess mates, and predators use volatile kairomones to locate prey. There is long-standing interest in understanding the pheromonal communication of insects and, in particular, exploring how semiochemicals govern the interactions of eusocial colonies. Ants are intriguing for the purposes of chemosensory studies, because of their diversity and exploitation of cuticular hydrocarbons (CHCs) for nest-mate recognition, and as signals of reproductive and caste status. Most ants live in closed societies within a shared colony or nest-with stereotypic social behaviors that involve a strict division of reproductive labor-in which multiple overlapping generations of sterile workers cooperate to nurture the progeny produced by the reproductives, which usually consist of single or small numbers of long-lived, highly fertile queens and short-lived male drones (1). Reproductive status within the colony is thought to be signaled primarily by a subset of the hydrocarbons secreted onto the external cuticle of insects and other arthropods (e.g. ref.2) that also func...

The importance of the aerosol mode for transmission of influenza is unknown. Understanding the role of aerosols is essential to developing public health interventions such as the use of surgical masks as a source control to prevent the release of infectious aerosols. Little information is available on the number and size of particles generated by infected persons, which is partly due to the limitations of conventional air samplers, which do not efficiently capture fine particles or maintain microorganism viability. We designed and built a new sampler, called the G-II, that collects exhaled breath particles that can be used in infectivity analyses. The G-II allows test subjects to perform various respiratory maneuvers (i.e. tidal breathing, coughing, and talking) and allows subjects to wear a mask or respirator during testing. A conventional slit impactor collects particles > 5.0 μm. Condensation of water vapor is used to grow remaining particles, including fine particles, to a size large enough to be efficiently collected by a 1.0 μm slit impactor and be deposited into a buffer-containing collector. We evaluated the G-II for fine particle collection efficiency with inert particle aerosols and evaluated infective virus collection using influenza A virus aerosols. Testing results showed greater than 85% collection efficiency for particles greater than 50nm and influenza virus collection comparable with a reference SKC BioSampler®. The new design will enable determination of exhaled infectious virus generation rate and evaluate control strategies such as wearing a surgical type mask to prevent the release of viruses from infected persons.

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A personal multipollutant sampler has been developed. This sampler can be used for measuring exposures to particulate matter and criteria gases. The system uses a single personal sampling pump that operates at a ow rate of 5.2 l/min. The basic unit consists of two impaction-based samplers for PM 2:5 and PM 10 attached to a single elutriator. Two mini PM 2:5 samplers are also attached to the elutriator for organic carbon (OC), elemental carbon (EC), sulfate, and nitrate measurements. For the collection of nitrate and sulfate, the minisampler includes a miniaturized honeycomb glass denuder that is placed upstream of the lter to remove nitric acid and sulfur dioxide and to minimize artifacts. Two passive samplers can also be attached to the elutriator for measurements of gaseous copollutants such as O 3 , SO 2 , and NO 2 .The performance of the multipollutant sampler was examined through a series of laboratory chamber tests. The results showed a good agreement between the multipollutant sampler and the reference methods. The overall sampler performance demonstrates its suitability for personal exposure assessment studies.

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This paper presents the design and development of a compact high volume cascade impactor (HVCI).The HVCI operates at a ow rate of 900 l/min and consists of 4 impaction stages equipped with circular slit-shaped acceleration nozzles and a backup lter. The backup lter is placed downstream of the fourth stage and is used to collect the ultra ne particles (d p < 0.1 ¹m). The major feature of this novel sampler is its ability to collect relatively large amounts of particles (mg-g levels) onto relatively small polyurethane foam substrates without using adhesives. As previously reported, the capacity of the impaction substrate is 2.15 g of collected particles per cm 2 of foam. Although the impaction substrates are not coated with adhesives such as grease or mineral oil, particle bounce and re-entrainment losses were found not to be signi cant. Particles can be easily recovered from the foam substrates using aqueous extraction. The impactor was calibrated using polydisperse particles. The 50% cutpoints of the 4 stages were 9.90, 2.46, 1.0, and 0.1 ¹m, respectively. Interstage losses of ultra ne and ne particles were <10% and for coarse particles were <20%. The pressure drop across the 4 stages and the backup lter were 0.25, 0.75, 1.25, 19.9, and 3.3 kPa, respectively.

supply them to an exposure chamber. Ambient aerosol containing particles in the size range 0.1-2.5 p m can be concentrated using a series of two slit-nozzle virtual impactors.The intake flow rates are 1 m3/min and 200 Umin in the first and second virtual impactors, respectively. The virtual impactors were characterized in terms of their cutpoints and interstage losses using artificial monodisperse fluorescent aerosols as well as indoor ambient aerosols. Since the concentrated particles are maintained airborne, they can be supplied to a human or animal exposure chamber for conduction of exposure studies. The supply flow rate in the prototype concentrator is 40 Umin. Higher flow rates can be achieved by using more than one such system in parallel.A number of studies have underlined the importance of the acute and chronic effects of ambient particles on respiratory health. Ambient particles can consist of natural materials such as pollen, and anthropogenic materials such as acid aerosols. Also, particles can be directly emitted by different sources (primary aerosols), or can be formed during the gas-to-particle con-