Behavioral responses of sexually active mud snails: kariomones and pheromones

We postulated that kariomones and pheromones function to organize egg capsule deposition and breeding aggregations of mud snails (Ilyanassa obsoleta). Sexually active male and female mud snails were exposed to water-born odors from juvenile snails, nonaggregated female snails, oysters, egg capsule depositing snails, sexually active males, sexually active females, and copulating snails and tested for a follow response using a ring assay. Neither sex responded to juvenile odor or to odor of sexually inactive females. Snails turned and followed water born odors from oysters. when tested with the odors of sexually active males, sexually active females, and copulating pairs, we found sex-specific differences in responses. Sexually active females followed the odor of sexually active males and ignored sexually active female odor. Sexually active males followed the odor of sexually active females and ignored sexually active male odor. Both sexes followed the odor of copulating pairs and egg capsule depositing snails. Snail activities in breeding aggregations are organized by at least three pheromones and one kariomone, and reflect the multifunctionaLity of the aggregations.     

Responses of Mud Snails and Periwinkles to Environmental Odors and Disaccharide Mimics of Fish Odor

Estuarine snails, periwinkles (Littoraria irorata), and mud snails (Ilyanassa obsoleta) were tested for behavioral responses to aqueous extracts of tissue macerates, odors of living intact organisms, and to disaccharides derived from heparin. Extracts included salt-marsh cordgrass (Spartina alterniflora), pink shrimp (Penaeus duorarum), crushed periwinkles, and crushed mud snails. Odors included live periwinkles, mud snails, stone crab (Menippe mercenaria), striped hermit crab (Clibanarius vittatus), tulip snail (Fasciolaria hunteria), and mummichog (Fundulus heteroclitus). Responses were determined upon contact by snails of a ring of solution in the bottom of an otherwise dry bowl and by presenting snails in seawater with 25 l of solution on a cotton swab. In each test, the response of 30 individuals was determined. Behaviors were recorded as fed, alarm, and no response. The strongest alarm response (>80% of all snails tested) in both snails was elicited by crushed mud snails. The strongest feeding response was to shrimp and periwinkle extract for mud snails (>70%), and salt-marsh cordgrass extract attracted periwinkles. High percentages of mud snails and periwinkles fled in response to the odors of intact snail predators, stone crabs, tulip snails, and mummichogs. Mud snails and periwinkles did not flee in response to nonpredator odors, including each other's odor, as well as that of hermit crabs, shrimp, and marsh cordgrass. Heparin disaccharides were tested because other studies reported that biological activity of predatory fish odor is due to similar disaccharides originating from fish mucus. Mud snail responses to disaccharides indicate that they respond to the same kinds of molecules as crustacean larvae and that the modified amine on the disaccharide is essential for activity. The Q-tip assay is appropriate for bioassay-directed purification of alarm signals originating in fish body odor.     

Influence of snail feces and mucus on oviposition and larval behavior ofPherbellia cinerella (Diptera: Sciomyzidae)

Larvae of the sciomyzid flyPherbellia cinerella are voracious predators of terrestrial helicid snails. Eggs are deposited in areas where snails occur and larvae hunt actively for their prey. Snail feces and mucus were tested to determine if they had any kairomone or stimulatory effects onP. cinerella. Adult flies oviposited more frequently on substrates containing fresh snail feces than on substrates containing snail mucus or water (control). However, mucus and feces both stimulated increased search behaviour in first instar larvae. These results are discussed in relation to snail biology, and the potential for augmentation of these flies in areas affected by pest snails.     

Behavioral responses ofLittoraria irrorata (SAY) to water-borne odors

Behavioral responses of the gastropod molluscLittoraria (=Littorina)irrorata indicate that it can discriminate among environmental odors. Snails were assayed for responses to 11 odors from plants and animals potentially representing food, shelter, location in the environment, and predators. Crushed conspecifics were included as an alarm odor. Except for odor of crushed conspecifics, all odor sources were water-borne from living intact organisms. Behavioral responses were categorized as no response, positive response, or negative response. For some analyses, negative responses were subdivided into withdrawing and turning responses. Snails responded positively to several plant odors. They did not respond to odors of intact conspecifics, fiddler crabs, or grass shrimp. They responded negatively to odors of a plant found at the upper limit of their minimal habitat, predatory blue crabs, crushed conspecifics, predatory gastropods, and ribbed mussels. Odors of blue crabs on different diets affect the type of negative response the snails display.     

Chemical attractants in horseshoe crab,Limulus polyphemus,eggs: the potential for an artificial bait

Horseshoe crabs, Limulus polyphemus, are the preferred bait in the eel and conch fisheries along the east coast of the United States. However, recent management measures have restricted the availability of horseshoe crabs to commercial fisheries, creating the need for sustainable, alternative bait sources. In this study, we examined the chemistry underlying the predator– prey attraction to determine if specific, isolable attractant metabolites from the horseshoe crab could be identified and characterized for incorporation into an artifical bait. Initial assays with the mud snail, Ilyanassa obsoleta, suggested that the chemoattractants were concentrated in L. polyphemus eggs. Chemical analyses and biological assays of the egg extract indicated the primary cue was a heat-stable, proteinaceous compound (>10 kDa). A carbohydrate-rich fraction of low molecular mass (<10 kDa) also enhanced mud snail chemotaxis. Analysis of egg digests with SDS-PAGE confirmed the presence of glycoproteins or carbohydrate-binding proteins in the horseshoe crab egg extract. Because the attractant appears to be a complex protein or glycoprotein, conventional chemical synthesis is unlikely. However, the tools of modern biotechnology offer the potential to produce this attractant in a system independent of the horseshoe crab. Such an attractant could be incorporated into an artificial bait, providing an ecologically sound alternative for commercial eel and whelk fisheries.     

Chemical discrimination of prey by naive neonate Gould's monitorsVaranus gouldii

Previous studies have demonstrated that actively foraging autarchoglossan lizards rely in part on chemoreception to detect and locate prey. In one of two experiments, neonate Gould's monitorsVaranus gouldii were studied to determine whether they were able to discriminate between multiple prey odors and control odors by tongue-flicking. Responses of lizards to deionized water, a pungency control (cologne), mouse, gecko, and cricket odors on cotton-tipped applicators were studied in experiments using repeated-measures designs and using the tongue-flick attack score (TFAS) as the primary measure of response strength. The TFAS was greater in response to cricket odors than to other prey odors or to either of the control stimuli, and there was no statistically significant difference in response between control stimuli. Range of tongue-flicks elicited by cricket odor were greater than those for other prey odors and control stimuli. Only applicators bearing cricket odor were bitten. In the second experiment, lizards were tested to determine whether they respond differently to chemical stimuli taken from the exoskeleton vs. internal fluids of crickets. TFAS were slightly higher for chemical stimuli taken from internal fluids, but not significantly so. Lizards bit applicators in both conditions. Details of responses to experimental trials are discussed in relation to the feeding behavior of this species.     

Immobilization of microorganisms within porous polymeric capsules

Porous capsules suitable for immobilizing yeast and Escherichia coli were prepared by the phase separation of poly(m‐phenylene isophthalamide) solution. The microorganisms were coated with starch or dextrin, which was subsequently extracted after capsule formation but served both to position the microorganisms in the capsule pores and to form spaces around the microorganisms. Fermentation experiments were carried out with capsules immobilizing yeast. Yeasts could be cultivated in the capsules, and effective release of CO₂ produced by the fermentation was observed with capsules prepared using polyethylene glycol because of the porous structure at the capsule surfaces. Notably, yeasts could be cultivated at high density even after 1 year. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Recombinant Snail Sialic Acid Aldolase is Promiscuous towards Aliphatic Aldehydes

Aldolases are enzymes that reversibly catalyze the cleavage of carbon-carbon bonds. Here we describe a recombinant sialic acid aldolase originating from the freshwater snail Biomphalaria glabrata (sNPL), and compare its substrate spectrum with a sialic acid aldolase originating from chicken (chNPL). In contrast to vertebrate animals which can synthesize, degrade, and incorporate sialic acids on glycoconjugate ubiquitously, snails (as all mollusks) cannot synthesize sialic acids endogenously, and therefore the biological function and substrate scope of sNPL ought to differ significantly from vertebrate sialic aldolases such as chNPL. sNPL was active towards a series of sialic acid derivatives but was in contrast to chNPL unable to catalyze the cleavage of N-acetylneuraminic acid into N-acetylmannosamine and pyruvate. Interestingly, chNPL and sNPL showed contrasting C4(R)/(S) diastereoselectivity towards the substrates d -mannose and d -galactose in the presence of pyruvate. In addition, sNPL was able to synthesize a series of 4-hydroxy-2-oxoates using the corresponding aliphatic aldehyde substrates in the presence of pyruvate, which could be not achieved by chNPL.     

Contact chemosensory cues in egg bundles elicit male-male agonistic conflicts in the squid Loligo pealeii

Male Loligo pealeii engage in frequent agonistic bouts to gain access to female mates while aggregated at communal egg beds. Male squids are attracted to eggs in the field and in the laboratory. It was recently demonstrated that visual detection followed by physical contact with egg capsules elicited male–male aggression. We tested specific physical and chemical features of the egg capsules that may cause this strong behavioral reaction. Male squids were presented with either natural or artificial egg stimuli and scored for four selected behaviors (egg touch, egg blowing, forward-lunge grab, and fin-beating), the last two of which are highly aggressive behaviors. First, squids were presented with natural eggs versus eggs sealed in agarose-coated tubes (ESACT), which eliminated both tactile and chemical stimuli. Second, males were presented with natural eggs versus eggs sealed in agarose coated tubes containing C₁₈ Sep-Pak-purified extracts (TCPE) from squid egg capsules, which provided chemical cues from natural eggs without the physical stimulus of the egg capsules. Third, natural eggs versus heat-denatured eggs were tested to determine whether the active factor in natural eggs is heat-labile. Squids responded aggressively when contacting natural eggs and TCPE, whereas squids did not respond after touching ESACT or denatured eggs. These results suggest that aggressive behavior is elicited by a heat-labile factor that is embedded within squid egg capsules. This chemosensory cue appears to be a contact pheromone that stimulates the agonistic interactions that characterize the mating behavior of migratory squids on inshore spawning grounds.     

Use of odor baits in traps to test reactions to intra- and interspecific chemical cues in house mice living in outdoor enclosures

House mice (Mus musculus) living in outdoor enclosures were tested for urinary chemical cue preferences using odor-baited traps. In the first experiment, with only volatile cues available, odors from conspecific males and females of various age classes and reproductive conditions were tested; no preferences were exhibited. In the second experiment mice had both nonvolatile and volatile cues available from the same sources as in experiment I. All age and sex class and female reproductive condition groups exhibited odor cue preferences except juvenile females. There were no specific odor cue preferences exhibited by any of the responder types with regard to odors from juvenile females. In the third and fifth experiments, mice were presented with nonvolatile plus volatile or only volatile urine odor cues, respectively, from four genera,Mus, Peromyscus, Microtus, andHomo. Mice of all age classes and both sexes preferredMus musculus odor, were neutral towardMicrotus ochrogaster odor, and avoided odors fromPeromyscus leucopus andHomo sapiens; these patterns were the same regardless of whether only volatile or both volatile and nonvolatile cues were presented. The fourth and sixth experiments involved testing volatile cues only and volatile cues plus nonvolatile cues from human sweat or feces from dogs, cats, or shrews. Mice avoided the human sweat and feces from cats and shrews, but were neutral toward the odor of dog feces. There were effects on whether mice were trapped in the interior of the enclosure or on the perimeter for some odors tested in these six experiments. The findings provide insights regarding possible functions of odor cues in the behavioral ecology of house mice. Odor-baiting traps can be an effective tool with respect to testing some, but not all questions pertaining to olfactory cues and house mouse social biology.     

Intraspecific and interspecific chemoattraction inBiomphalaria glabrata andHelisoma trivolvis (Gastropoda: Planorbidae)

A Petri dish bioassay previously used to examine food preferences in planorbid snails was used to study intraspecific and interspecific chemoattraction inBiomphalaria glabrata (albino strain, M-line) andHelisoma trivolvis (Colorado strain) snails.B. glabrata snails showed significant intraspecific chemoattraction in the absence of visual cues and snail thigmotaxis.H. trivolvis snails also showed significant intraspecific chemoattraction. Interspecific chemoattraction between these species occurred in the bioassay, suggesting that the chemoattractants were not species specific. Artificial spring water conditioned by aqueous excretory-secretory products (snail-conditioned water) ofB. glabrata elicited significant intraspecific chemoattraction. However, lipophilic excretory-secretory products ofB. glabrata elicited significant chemorepulsion. Repellant factors in the lipophilic fraction were not characterized.     

Volatile Foraging Kairomones in the Littoral Zone: Attraction of an Herbivorous Freshwater Gastropod to Algal Odors

Volatile organic compounds (VOCs) produced by algae and cyanobacteria are primarily responsible for odors in fresh waters. Among other functions, VOCs may serve as important infochemicals in biofilms of benthic primary producers. VOCs liberated by benthic, mat-forming cyanobacteria can be used as habitat-finding cues by insects, nematodes, and possibly other organisms. We developed a new gastropod behavioral assay that allows detection of food preference without offering food, thus allowing the distinction between taste, which requires direct contact with the food source, and the detection of odorous infochemicals, which work over distance. We demonstrated that VOCs released from disintegrated cells of a benthic, mat-forming, green alga (Ulothrix fimbriata) are food-finding cues (“foraging kairomones”) that attract the herbivorous freshwater snail Radix ovata. A mixture of three C₅ lipoxygenase compounds and 2(E),4(E)-heptadienal that mimic the major VOCs released by U. fimbriata attracted the snails, whereas neither the mixture of C₅ compounds nor 2(E),4(E)-heptadienal were effective when given alone. This study suggests that VOCs can play a steering role as infochemicals in freshwater benthic habitats, as has been established for many organismic interactions in terrestrial ecosystems.     

Assembling photosensitive capsules by phthalocyanines and polyelectrolytes for photodynamic therapy

A photosensitive capsule consisting of aluminum phthalocyanine tetrasulfonate chloride (AlPcS₄Cl) and polyelectrolytes was fabricated by assembling of oppositely charged poly(allylamine hydrochloride) (PAH) and AlPcS₄Cl onto the preformed capsules composed of poly(styrene sulfonate) (PSS) and PAH. UV-visible absorption spectra, EDX spectrum and AFM images confirmed the successful deposition of AlPcS₄Cl onto as-prepared hollow capsules. The assembled photosensitive capsules were found to remain intact and spherical morphology in the deposition process. The generation of cytotoxic singlet oxygen (¹O₂) of photosensitive capsules under visible light irradiation (670 ± 10 nm) was evidenced by ESR measurements and the oxidative reaction between the generated ¹O₂ and a detector. In vitro cellular experiments showed that photosensitive capsules exhibited a good biocompatibility in the dark and a higher killing efficacy against MCF-7 cancer cells under visible light irradiation as compared with free AlPcS₄Cl, which implies that the assembled photosensitive capsules might be potentially applicable in photodynamic therapy.     

Determination of the elastic properties of single microcapsules using micromanipulation and finite element modeling

Finite element modeling (FEM) has been used to simulate the compression of single elastic core–shell capsules between two parallel plates. FEM allows characterizing the compressions at deformations beyond the wall thickness, when both bending and stretching contribute to the force resisting compression. Due to the incorporation of bending effects, the force deformation profiles of capsules with the same elastic modulus E depend on the wall thickness to capsule radius ratio (h/r). A model is presented that enables the (i) calculation of h/r from the individual compression force profiles at fractional deformations lower than 0.1, thus applicable for brittle capsules and for elastic–plastic capsules and (ii) calculation of Eh by comparison with FEM data at that h/r. Thus, the model allows the determination of E from compression data alone, as the wall thickness is also determined. The compression of melamine–formaldehyde capsules with a hexyl salicylate core using a micromanipulation technique is given as an example of the application of the model. The estimated wall thickness value, found to be independent of the capsule size, is in excellent agreement with transmission electron microscopy measurements.     

Differences in Induced Volatile Emissions among Rice Varieties Result in Differential Attraction and Parasitism of Nilaparvata lugens Eggs by the Parasitoid Anagrus nilaparvatae in the Field

We compared the volatiles of JA-treated plants of six rice varieties and then determined, in the laboratory and field, if they differed in attractiveness to Anagrus nilaparavate Pand et Wang, an egg parasitoid of rice planthoppers. Analyses of volatiles revealed significant differences among varieties, both in total quantity and quality of the blends emitted. On the basis of these differences, the six varieties could be roughly divided into three groups. In a Y-tube olfactometer, female wasps preferred odors from two groups. These preferences corresponded to observed parasitism rates in a field experiment. A comparison of the volatiles with results from behavioral assays and field experiments indicates that the quality (composition) of the blends is more important for attraction than the total amount emitted. The results imply that the foraging success of natural enemies of pests can be enhanced by breeding for crop varieties that release specific volatiles.     

Sequestration of lichen compounds by three species of terrestrial snails

Three species of lichen-grazing snails,Balea perversa, Chondria clienta, andHelicigona lapicida, all from the Swedish island of Öland, were found to sequester lichen compounds when feeding on the crustous lichen speciesAspicila calcarea, Caloplaca flavovirescens, Lecanora muralis, Physcia adscendens, Tephromela atra, andXanthoria parietina. The lichen compounds detected in the soft bodies of the snail species analyzed included the anthraquinone parietin, the depside atranorin, as well as a presumable degradation product of the latter. Other lichen compounds such as (+)-usnic acid or -collatolic acid were not found in the soft bodies but were only detected in the feces, suggesting selective uptake of lichen compounds by the snails. In individuals ofC. clienta initially fed on the lichenX. parietina, the amount of sequestered parietin decreased over time on a parietin-free diet but was still detectable in the soft bodies after 28 days. In the ovoviviparous land snail,B. perversa, sequestered parietin was transferred from the mother to the eggs in the reproductive tract.Dedicated to Prof. Dr. F.-C. Czygan on the occasion of his 60th birthday.     

Steroids from aquatic organisms: V. Main sterols of the fresh water snail,Biomphalaria tenagophila

The free sterols of the snail,Biomphalaria tenagophila, were isolated and characterized by means of gas chromatography and gas chromatography-mass spectrometry techniques. The mixture contains the common steroids found in freshwater molluscs, principally cholesterol. The presence of cholesta-5,7-dien-3β-ol is without precedent in freshwater organisms. The occurrence of 7-oxo-cholesterol in freshwater snails, but not bivalves, from the same freshwater source, would indicate a difference in the physiology of such snails and bivalves.     

Evaluation of mechanical and thermal properties of carrageenan/hydroxypropyl methyl cellulose hard capsule

The inherent source of gelatin used for commercial hard capsules causes a surging demand for vegetarian capsules. In this work, carrageenan is utilized in preparing hard capsules to meet consumer preferences. Hydroxypropyl methylcellulose (HPMC) was incorporated as a reinforcing agent to improve the low mechanical properties of hard capsules made of carrageenan. The HPMC concentration was manipulated from 0.2 to 1.0 w/v% in the carrageenan matrix. The increasing concentration of HPMC exerts significant effects on the tensile strength and elongation at break, with an improvement of 59.1% and 46.9%, respectively, at the optimized HPMC concentration of 0.8 w/v%. The loop strength of the capsule is also increased by 56.4% with decreasing moisture content. The downfield movement from around 3.20 ppm of the carrageenan proton to 3.33 ppm in the proton nuclear magnetic resonanance ( ¹H-NMR) spectrum suggests the formation of intermolecular hydrogen bonding between carrageenan and HPMC, which correlates to the results of Fourier-transform infrared spectroscopy (FTIR) and zeta potential. The glass transition temperature of the film was increased from 37.8 to 65.3°C, showing an upgrade in thermal stability. The film possesses a major mass loss with an activation energy of 64.7 kJ/mol with an increment of 43.4% compared to the control carrageenan. These findings support the conclusion that HPMC enhanced the mechanical properties and thermal stability of the carrageenan film, and the comprehensive analysis of the molecular interaction and decomposition kinetics subsequently may expand the application fields of the carrageenan-HPMC hard capsule as an alternative to gelatin in the future.     

Temperature‐dependent permeability of polyelectrolyte complex capsule membranes having N‐isopropylacrylamide domains

As a microcapsule with temperature sensitivity, poly(methacrylic acid)–polyethylenimine complex capsules containing N‐isopropylacrylamide units were designed. Two kinds of copolymers of methacrylic acid and N‐isopropylacrylamide were synthesized by free‐radical copolymerization. Partly crosslinked poly(methacrylic acid)–polyethylenimine complex capsules containing the methacrylic acid–N‐isopropylacrylamide copolymers were prepared at 40 or 25°C. The permeation of phenylethylene glycol through the capsule membranes was investigated. Permeability of the capsules prepared at 25°C increased monotonously with increasing temperature from 10 to 50°C. Permeability of the capsules prepared at 40°C also increased with increasing temperature up to 25°C but decreased above 30°C. Also, the degree of swelling of the membranes prepared at 40°C decreased above 30°C. Differential scanning calorimetry measurement showed that N‐isopropylacrylamide units underwent more efficient transition in the capsule membranes prepared at 40°C than in the membranes prepared at 25°C. The capsule membranes prepared at 40°C might have domains in which N‐isopropylacrylamide units are concentrated, whereas these units should distribute uniformly in the capsule membranes made at 25°C. Such a difference in distribution of N‐isopropylacrylamide units might result in the different permeation property of the capsule membranes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2703–2710, 2000     

Odors influence choice of oviposition sites byDiabrotica virgifera virgifera (Coleoptera: Chrysomelidae)

FemaleDiabrotica virgifera virgifera LeConte were allowed to choose between oviposition substrates that were and those that were not associated with potential sources of semiochemicals. Females deposited over five times more eggs on moist towelettes that were treated with homogenates of female abdomens than on towelettes treated with distilled water. Similar results were obtained when screening separated the homogenates from the towelettes, indicating that odors alone could elicit the response. In contrast, females did not choose towelettes that had previously been used for oviposition or towelettes containing eggs over unused towelettes. Further tests with homogenates of abdomens and a bacteriostatic agent (sorbate) indicated that the females were probably responding to bacterial odors rather than an oviposition-enhancing pheromone. Four strains of bacteria were isolated from a homogenate of female abdomens; females deposited 4 to 16 times more eggs on substrates with odors of the bacteria than on substrates with odors of uninoculated nutrient agar. In no-choice tests, bacterial odors did not increase the number of eggs deposited per female beetle; however, in choice tests with dishes that tended to retain any beetles that entered, there were more eggs per female (but not more beetles) after 24 hr in dishes with bacterial odors than in those without the odors. Females also chose dishes with odors of excised maize (Zea mays L.) roots or elevated levels of carbon dioxide over control dishes.Mention of a commercial or proprietary product does not constitute an endorsement for its use by USDA.