Atrial Gland Research Articles

Redescription of the earthworm Moniligaster gravelyi Stephenson, 1915 (Clitellata, Moniligastridae) based on recent collections from Kerala state, India.

Earthworms of the genus Moniligaster Perrier, 1872 can be distinguished from other genera of the family Moniligastridae by the presence of spermathecal atrial glands. Moniligaster gravelyi Stephenson, 1915 has so far been known only from a single specimen, and it is the only species with supposed single spermathecal atrial gland in the genus. Hence, this species has been a subject to some taxonomic confusion. Here, M. gravelyi is redescribed from new material collected and illustrated for the first time. The current study expanded its description and provided a more comprehensive taxonomic characterization of the species. Comparison of the species with closely related species are also made. Apart from this detailed information on its habitat and geographical range is also provided.

The anatomy and histology of the reproductive system of Aplysia oculifera (Mollusca: Heterobranchia: Aplsiida) from the Red Sea coastal waters

ABSTRACT Aplysia oculifera is an endemic sea hare that inhabits the Egyptian coast of the Red Sea. We describe the reproductive system of this species for the first time. It is composed of an ovotestis, small hermaphroditic duct, nidamental glandular complex, large hermaphroditic duct, gametolytic gland, external seminal groove and cephalic penis. The follicles within the ovotestis contain spermatogenic and oogenic cells. A pre-ampulla, ampulla, and post-ampulla constitute the different regions of the small hermaphroditic duct. The nidamental complex consists of albumen, mucus, and membrane glands all confluent with the fertilization chamber. The nidamental glands consist of glandular cells alternating with supporting cells. The glandular cells have different histochemical characters concerning the production of acid and neutral mucopolysaccharides. The large hermaphroditic duct is attached to a seminal receptacle. The duct has two components; red and white hemiducts the secretory epithelia of which are distinguished internally. An atrial gland is present near the visceral genital opening. The gametolytic gland has four types of columnar cells. A seminal groove arises from the genital opening and extends anteriorly to the apex of an ear-like flap penis. The results suggest that some differences in certain reproductive characters may be of phylogenetic importance.

A Novel Pyridoxal 5′-Phosphate-dependent Amino Acid Racemase in the Aplysia californica Central Nervous System

D-aspartate (D-Asp) is found in specific neurons, transported to neuronal terminals and released in a stimulation-dependent manner. Because D-Asp formation is not well understood, determining its function has proved challenging. Significant levels of D-Asp are present in the cerebral ganglion of the F- and C-clusters of the invertebrate Aplysia californica, and D-Asp appears to be involved in cell-cell communication in this system. Here, we describe a novel protein, DAR1, from A. californica that can convert aspartate and serine to their other chiral form in a pyridoxal 5'-phosphate (PLP)-dependent manner. DAR1 has a predicted length of 325 amino acids and is 55% identical to the bivalve aspartate racemase, EC 5.1.1.13, and 41% identical to the mammalian serine racemase, EC 5.1.1.18. However, it is only 14% identical to the recently reported mammalian aspartate racemase, DR, which is closely related to glutamate-oxaloacetate transaminase, EC 2.6.1.1. Using whole-mount immunohistochemistry staining of the A. californica central nervous system, we localized DAR1-like immunoreactivity to the medial region of the cerebral ganglion where the F- and C-clusters are situated. The biochemical and functional similarities between DAR1 and other animal serine and aspartate racemases make it valuable for examining PLP-dependent racemases, promising to increase our knowledge of enzyme regulation and ultimately, D-serine and D-Asp signaling pathways.

LOCALIZATION OF THE EXPRESSION OF GONADOTROPIN-RELEASING HORMONE LIKE-MOLECULE IN A GASTROPOD MOLLUSK, APLYSIA CALIFORNICA.

Event Abstract Back to Event LOCALIZATION OF THE EXPRESSION OF GONADOTROPIN-RELEASING HORMONE LIKE-MOLECULE IN A GASTROPOD MOLLUSK, APLYSIA CALIFORNICA. Lisa H. Jung1*, Scott I. Kavanaugh1 and Pei-San Tsai1 1 University of Colorado at Boulder, Integrative Physiology, United States Gonadotropin- releasing hormone (GnRH) is a key neuropeptide for regulating reproduction in vertebrates. The recent discoveries of GnRH-like molecules in non-chordate animals suggested GnRH may have arisen in an ancestral bilaterian that gave rise to both protostomes and deuterostomes. Our laboratory has previously isolated a full-length cDNA of a GnRH-like molecule, named ap-GnRH, from a gastropod mollusk, Aplysia californica. Immunocytochemistry revealed the presence of neurons positive for ap-GnRH in only 2 central ganglia, the pedal and cerebral ganglia, of A. californica, but a specific radioimmunoassay revealed that all 5 central ganglia contained immunodetectable ap-GnRH, leading to some confusion regarding the source of this peptide. The goal of the present study is to localize ap-GnRH transcript in central and peripheral tissues of A. californica by in situ hybridization (ISH). Using a 604 nt-cRNA probe, we detected the strong presence of ap-GnRH transcript in neurons of the pedal ganglia. In addition, many positive neurons were localized in the cerebral ganglia, followed by 1-4 neurons in the abdominal ganglia. No staining was observed in the remaining central ganglia (buccal and pleural ganglia) or in the peripheral tissues (the ovotestis and atrial gland). These data are largely consistent with our previous immunocytochemical data and support the presence of both ap-GnRH peptide and transcript in the pedal and cerebral ganglia. However, the presence of ap-GnRH mRNA in the abdominal ganglia suggests transcriptional activity also occurs in these ganglia. As such, our inability to detect abdominal ap-GnRH immunoreactive neurons may reflect either alternative processing or exceptionally fast turnover of the peptide in these ganglia. Overall, our data suggest that ap-GnRH is produced by multiple ganglia and support the notion that ap-GnRH may assume functions beyond reproduction. (Supported by NSF IOS 0743818 to PST) Keywords: ap-GnRH transcript, Aplysia Californica, evolution, gonadotropin-releasing hormone like-molecule Conference: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011. Presentation Type: Poster Topic: General neuroendocrinology Citation: Jung LH, Kavanaugh SI and Tsai P (2011). LOCALIZATION OF THE EXPRESSION OF GONADOTROPIN-RELEASING HORMONE LIKE-MOLECULE IN A GASTROPOD MOLLUSK, APLYSIA CALIFORNICA.. Front. Endocrinol. Conference Abstract: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology. doi: 10.3389/conf.fendo.2011.04.00150 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 18 Jul 2011; Published Online: 09 Aug 2011. * Correspondence: Miss. Lisa H Jung, University of Colorado at Boulder, Integrative Physiology, Boulder, Colorado, 80309, United States, lisa.jung@colorado.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Lisa H Jung Scott I Kavanaugh Pei-San Tsai Google Lisa H Jung Scott I Kavanaugh Pei-San Tsai Google Scholar Lisa H Jung Scott I Kavanaugh Pei-San Tsai PubMed Lisa H Jung Scott I Kavanaugh Pei-San Tsai Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Reflections

Reflections

Molecular cloning, expression pattern, and immunocytochemical localization of a gonadotropin-releasing hormone-like molecule in the gastropod mollusk, Aplysia californica

Successful reproduction in vertebrates depends upon the actions of gonadotropin-releasing hormone (GnRH). Despite the wide presence of GnRH in Phylum Chordata, GnRH has not been isolated in protostomes other than the common octopus. To provide information on the evolution of this critical hormone, we isolated the full-length cDNA of a GnRH-like molecule from the central nervous system of a gastropod mollusk, the sea hare Aplysia californica. The open reading frame of this cDNA encodes a protein of 147 amino acids. The molecular architecture of the deduced protein is highly homologous to that reported for the prepro-octopus GnRH (oct-GnRH) and consists of a putative signal peptide, a GnRH dodecapeptide, a downstream processing site, and a GnRH-associated peptide (GAP). The deduced amino acid sequence of the Aplysia GnRH (ap-GnRH) is QNYHFSNGWYAG and differs from oct-GnRH by only two amino acids. The transcript for ap-GnRH is widely expressed in the central nervous system (CNS), the ovotestis, and the atrial gland, an exocrine gland. Immunocytochemistry (ICC) using an antiserum against oct-GnRH detected immunoreactive neurons in all CNS ganglia examined, and the staining was abolished by the preadsorption of the antiserum with synthetic ap-GnRH. In sum, ap-GnRH sequence is the first gastropod GnRH-like molecule to be elucidated. Further, it represents one of the only two GnRH-like molecules found outside Phylum Chordata. These data refute the possibility that oct-GnRH arose singly in cephalopods by convergent evolution and provide valuable support for an ancient origin of GnRH during metazoan evolution.

Characterization of Aplysia Alb-1, a candidate water-borne protein pheromone released during egg laying

Pheromones are known to be important to the innate behavior of marine animals. Attraction in Aplysia involves the long-distance water-borne protein pheromones attractin, enticin, temptin and seductin, which are released from the albumen gland during egg laying. Other pheromones are predicted to act in concert with these pheromones, but their identities are unknown. To identify additional pheromone candidates, we employed differential library screening of an albumen gland cDNA library, RT-PCR, recombinant protein expression, rhinophore contraction bioassays and immunocytochemistry. Alb-1 is expressed in the Aplysia californica albumen gland and encodes a novel protein that does not share significant sequence identity with any proteins in the database. RT-PCR analysis detected Alb-1 transcripts in the albumen gland, exocrine atrial gland and ovotestis. The Alb-1 precursor has a signal peptide sequence followed by a predicted 101-residue protein sequence containing eight cysteine residues. Recombinant protein expression, RP-HPLC, microsequence analysis and MALDI mass spectrometry analyses demonstrated that mature recombinant Alb-1 was processed at a paired basic residue site to generate an N-terminal and C-terminal protein fragment; this was consistent with immunoblot observations on purified albumen gland extracts. In rhinophore contraction (twitch) bioassays, the recombinant N-terminal protein induced rhinophore contractions whereas the C-terminal protein did not. An antibody generated to the N-terminal protein was used for immunocytochemical and immunoblot analyses and demonstrated that this protein is present in albumen gland secretory cells, egg cordons and egg eluates. Overall, the data suggest that Alb-1 may be processed in the albumen gland and that the Alb-1 1–56 protein released during egg laying may serve a pheromonal function in concert with attractin, enticin, temptin and seductin.

Peptide products of the atrial gland are not water-borne reproductive pheromones during egg laying in Aplysia

Mate attraction in Aplysia involves long-distance water-borne signaling via the secretion of the peptide pheromone attractin from the exocrine albumen gland during egg laying. Previous studies have shown that a second exocrine organ, the atrial gland, produces abundant egg-laying hormone (ELH) precursor-related peptides and mollusk-derived growth factor (MDGF), and crude extracts of the atrial gland are attractive in T-maze attraction assays. However, it is not known whether these peptides and proteins are secreted during egg laying. In this report, seawater eluates of freshly laid egg cordons were concentrated and fractionated by C18 RP-HPLC, and the resulting major peaks were examined by amino acid compositional analysis, microsequence analysis, and electrospray mass spectrometry. Concentrated egg cordon eluates were also examined by immunoblot analysis using anti-MDGF antisera as probe. The combined data demonstrated that the atrial gland of Aplysia californica does not secrete detectable levels of either ELH precursor-related peptides or MDGF during egg laying. Although the atrial gland is the last major exocrine organ to make contact with eggs before they are laid, the gland does not appear to secrete water-borne peptide pheromones during egg laying.

Direct assay of Aplysia tissues and cells with laser desorption/ionization mass spectrometry on porous silicon.

Desorption/ionization on porous silicon (DIOS) is a form of laser desorption mass spectrometry that allows for the direct mass analysis of a variety of analytes without the addition of organic matrix. Protocols are described for the direct analysis of exocrine tissue and single neurons using DIOS-MS. The atrial gland of Aplysia californica was blotted on to porous silicon and analyzed with DIOS-MS in the range m/z 1000-4000. The ability to culture invertebrate neurons directly on porous silicon is also presented. Isolated bag cells regenerated neuronal processes in culture on porous silicon. DIOS-MS allowed the direct detection of the peptides contained in individual cultured neurons indicating that with appropriate protocols, DIOS can be used with biological samples with considerable thickness.

Mollusk-derived growth factor: cloning and developmental expression in the central nervous system and reproductive tract of Aplysia

We have isolated and characterized an atrial gland cDNA that corrects the previously reported sequence for Aplysia atrial gland granule-specific antigen (AGSA), a glycoprotein of unknown function. We designated the protein mollusk-derived growth factor (MDGF) to distinguish the revised sequence from AGSA and to emphasize its similarity to an insect-derived growth factor (IDGF). We describe MDGF mRNA expression that suggests a possible role during embryonic development and CNS injury repair.

Interaction of edrophonium with muscarinic acetylcholine M2 and M3 receptors.

It has been reported that edrophonium can antagonize the negative chronotropic effect of carbachol. This study was undertaken to evaluate in detail the interaction of edrophonium with muscarinic Mz and M3 receptors. A functional study was conducted to evaluate the effects of edrophonium on the concentration-response curves for the negative chronotropic effect and the bronchoconstricting effect of carbachol in spontaneously beating right atria and tracheas of guinea pigs. An electrophysiologic study was conducted to compare the effects of edrophonium on carbachol-, guanosine triphosphate (GTP)gama S-, and adenosine-induced outward K+ currents in guinea pig atrial cells by whole cell voltage clamp technique. A radioligand binding study was conducted to examine the effects of edrophonium on specific [3HIN-methylscopolamine (NMS) binding to guinea pig atrial (M2) and submandibular gland (M3) membrane preparations, and on atropine-induced dissociation of [3H]NMS. Edrophonium shifted rightward the concentration-response curves for the negative chronotropic and bronchoconstricting effects of carbachol in a competitive manner. The pA2 values for cardiac and tracheal muscarinic receptors were 4.61 and 4.03, respectively. Edrophonium abolished the carbachol-induced outward current without affecting the GTPgamma S- and adenosine-induced currents in the atrial cells. Edrophonium inhibited [3H]NMS binding to M2 and M3 receptors in a concentration-dependent manner. The pseudo-Hill coefficient values and apparent dissociation constants of edrophonium for M2 and M3 receptors were 1.02 and 1.07 and 21 and 34 microM, respectively. Edrophonium also changed dissociation constant values of [3H]NMS without affecting its maximum binding capacities. Edrophonium binds to muscarinic M2 and M3 receptors nonselectively, and acts as a competitive antagonist.

A family of genes with growth factor and adenosine deaminase similarity are preferentially expressed in the salivary glands of Glossina m. morsitans

A cDNA library constructed from salivary glands of tsetse fly, Glossina morsitans morsitans (Diptera: Glossinidae), was differentially screened, and two related full-length cDNAs were molecularly characterized: tsetse salivary growth factor, TSGF-1 and TSGF-2. The cDNAs encode for open reading frames (ORFs) of 494 and 506 aa, respectively, and display an overall 45% amino acid identity and 61% similarity to one another. Both genes are preferentially expressed in the salivary glands of male and female adult flies. In addition to salivary glands, both transcripts can be detected from the gut tissue. Only transcripts specific for TSGF-2 are detected in ovary and testes tissues of adults as well as in puparia, while neither gene is expressed during the larval developmental stages. The N-terminal region of both putative proteins contains a hydrophobic sequence with secretory signal peptide characteristics, and analysis of proteins in saliva by Western blot indicates that both are secreted. Western blot analysis indicates that TSGF-1 is synthesized at significantly higher levels than TSGF-2. The deduced protein sequences of both cDNAs display extensive similarities to two other proteins: insect derived growth factor (IDGF) characterized from Sarcophaga peregrina with growth-factor activity, and atrial gland specific antigen (AGSA or MDSF) characterized from Apylasia californica. In addition to growth factor similarity, all four related proteins share the evolutionarily conserved amino acid residues associated with the enzymatic deamination of adenosine, which is shown here to be present in salivary gland extracts of tsetse. While both genes are present and expressed in G. m. morsitans and G. p. palpalis, only TSGF-1 is present in G. austeni. We present the molecular characteristics of the cDNAs, their genomic arrangement and their regulation of expression in different fly tissues and species. We discuss the potential role of these proteins in hemostatis and in African trypanosome transmission by different species of tsetse.

Measuring the peptides in individual organelles with mass spectrometry.

New sampling protocols combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) allow the assay of single dense core vesicles. Understanding the packaging of vesicles is important as vesicles are the quanta of information for intercellular communication. Using vesicles from the exocrine atrial gland of Aplysia californica as the model, a wide range of bioactive peptides are detected within each vesicle. Although the expression of the egg-laying hormone gene family of type 1 atrial gland cells has been previously examined, chemical characterization of individual 1-2 microm diameter vesicles demonstrates that products from several genes are colocalized. The mass sensitivity of MALDI MS can be further improved to enable the analysis of even smaller subcellular organelles.

In situ sequencing of peptides from biological tissues and single cells using MALDI-PSD/CID analysis.

The ability to directly sequence peptides from biological cells using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with postsource decay (PSD) and collision-induced dissociation (CID) fragment ion mass analysis is explored. Three different sample preparation methods are described for sequencing peptides in tissue samples and in single neurons from the invertebrate model Aplysia californica. To characterize peptides from the atrial gland, MALDI-PSD/CID is applied directly to a tissue blot covered with the matrix alpha-cyano-4-hydroxycinnamic acid (CHCA). The resulting fragment ions combined with database searching confirm the structure of several novel peptides encoded by egg-laying hormone genes. Moreover, MS profiling of a single unidentified neuron detects peptides with molecular weights of myomodulins C and E; this assignment is confirmed using MALDI-PSD with the matrix 2,5-dihydroxybenzoic acid (DHB). DHB does not always provide adequate fragmentation for PSD experiments; therefore, a unique dual-matrix sampling method, employing both DHB and CHCA, is developed to directly sequence a decapeptide from a single cerebral ganglion B cell. Mass accuracy of fragment ions from cellular samples is typical for the instrument employed and is not deleteriously affected by the morphology and complexity of the samples.

Attractin, a water-borne peptide pheromone in Aplysa

Summary The opisthobranch mollusk Aplysia is a simultaneous hermaphrodite that does not usually fertilize its own eggs. It is solitary during most of the year, but moves into breeding aggregations during the summer reproductive season. The aggregations contain both mating and egg-laying animals and are associated with masses of egg cordons. The egg cordons are a source of both contact and water-borne pheromones that attract animals to the area and induce or facilitate reproductive activity. Three characteristics of the Aplysia reproductive system make it ideal for the isolation and characterization of a water-borne peptide pheromone: (a) egg laying can be induced by injecting atrial gland extract into the hemocoel; (b) the resulting eggs are packaged into a long string or “cordon” which has a large surface area; and (c) the cordon is a source of water-borne pheromones. By using atrial gland extract to induce egg laying, it is possible to control the number of animals laying eggs, the timing and synchronization of egg laying, the general area in which the eggs are deposited and, to some extent, the purity of the seawater in which they are deposited. In terms of the resulting “cordon-derived” pheromones, this means that it is possible to control the timing of pheromone secretion, the amount of pheromone secreted, and the relative amount of contaminants in the seawater. This approach was used in the studies described in this paper to isolate and characterize a peptide that is a water-borne pheromonal attractant in Aplysia. To the best of our knowledge, it is the first water-borne peptide pheromone characterized in mollusks and in invertebrates. Some of these studies have been reported previously (Painter et al., 1998).

Separation and characterization of amines from individual atrial gland vesicles of Aplysia californica.

Several amine-containing components of individual vesicles from the atrial gland of Aplysia californica were identified with capillary electrophoresis (CE). On-line derivatization with naphthalene-2,3-dicarboxaldehyde was performed, and the derivatized amine-containing components were detected with laser-induced fluorescence (LIF). Amino acids, including taurine, that had not been determined previously in atrial gland vesicles were observed by using CE-LIF, and their identities were confirmed with CE, HPLC, NMR, and electrospray ionization mass spectrometry. The finding that taurine is packaged and stored into secretory vesicles supports the hypothesis that taurine may exhibit neuromodulatory activity. The bioactive peptides, well-known to be in atrial gland vesicles, were detected in lysed vesicle samples fractionated with HPLC and analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. These peptides were also observed in single-vesicle runs with CE-LIF. The atrial gland vesicles (ranging from 0.5 to 2 microns diameter and 65 aL to 4 fL volume, respectively) studied in this work represent the smallest biological entities to be analyzed chemically on an individual basis.

Pheromones linked to sexual behaviors excite the appetitive phase of feeding behavior of Aplysia fasciata . I. Modulation and excitation of appetitive behaviors

Pheromones presumably secreted by mating conspecifics – as well as homogenates containing tissue that is homologous with the atrial gland – increase the time that Aplysia fasciata spend feeding. This effect is caused by increasing the number of feeding episodes initiated in response to food, whereas the duration of a feeding bout remains unchanged. The increase in the number of feeding episodes is related to increases in head waving and crawling, i.e., appetitive movements that bring the animal into contact with food, as well as an increase in the responsiveness to food after it is contacted. Releasing a homogenate containing atrial gland tissue, or egg laying hormone, in the water near the animal elicited head lifting similar to that seen when animals are food aroused. The data indicate that the facilitation of Aplysia feeding caused by pheromones arises in part by an excitation of appetitive behaviors. These findings suggest that neurons generating appetitive behaviors will be affected by pheromones.

Pheromones linked to sexual behaviors excite the appetitive phase of feeding behavior of Aplysia fasciata II. Excitation of C-PR, a neuron involved in the generation of appetitive behaviors

Pheromones presumably released by conspecifics amplify both the appetitive and the consummatory components of feeding in Aplysia. These effects can be mimicked by administering homogenate of the large hermaphroditic duct containing atrial gland tissue, as well as peptides from the bag cells. Identified cerebro-pedal regulator (C-PR) neuron is thought to command various behaviors that comprise the appetitive phase of feeding. In a reduced preparation, we investigated the effects on the C-PR of applying these substances to the rhinophores, the sensory organs which detect pheromones. Stimuli that excite feeding in the animal were also found to affect the C-PR. Large hermaphroditic duct homogenate caused a doubling in the firing rate of the C-PR, and amplified the response of the C-PR to other excitatory stimuli, such as touch of food to the rhinophores. Bag cell peptides (α, β and γ bag cell peptide, and egg-laying hormone) caused smaller increases in the firing rate of the C-PR. These data are consistent with the hypothesis that pheromones facilitate appetitive feeding behavior in part via their excitation of C-PR.

Probing single secretory vesicles with capillary electrophoresis.

Secretory vesicles obtained from the atrial gland of the gastropod mollusk Aplysia californica were chemically analyzed individually with a combination of optical trapping, capillary electrophoresis separation, and a laser-induced fluorescence detection. With the use of optical trapping, a single vesicle that had attoliters (10(-18) liters) of volume was introduced into the tapered inlet of a separation capillary. Once the vesicle was injected, it was lysed, and its components were fluorescently labeled with naphthalene-2, 3-dicarboxaldehyde before separation. The resultant electropherograms indicated distinct variations in the contents of single vesicles.

Consummatory feeding movements in Aplysia fasciata are facilitated by conspecifics with access to mates, by reproductive tract homogenates and by bag cell peptides

In Aplysia fasciata, pheromones released by conspecifics with access to mates increase the quantity of food eaten. This effect is blocked when the chemosensory rhinophores are ablated, indicating that the rhinophores sense pheromones. The modulation of feeding by pheromones can be monitored by an increase in the amplitude of swallowing movements in the presence of conspecifics with access to mates. Atrial gland homogenates and four bag cell peptides (egg-laying hormone, and α, β, and γ bag cell peptides) amplify the swallow amplitude in a manner similar to that caused by conspecifics with access to mates, suggesting that peptides from the bag cell/atrial gland family that are released from the atrial gland into the surrounding water may be pheromones regulating feeding and reproductive behaviors.