Pleural Ganglia Research Articles

Comparative Neuroanatomy of Pediveliger Larvae of Various Bivalves from the Sea of Japan.

Here, we describe the nervous system structures from pediveligers of eight bivalve species (Callista brevisiphonata, Mactromeris polynyma, Crenomytilus grayanus, Kellia japonica, Mizuhopecten yessoensis, and Azumapecten farreri) with different modes of life in their adult stages, corresponding to the ecological niches that they occupy (burrowing, cemented, byssally attached, and mobile forms). We have identified neuromorphological features of the central and peripheral nervous systems in larval bivalves. We show that the unpaired sensory apical organ is still present in pediveligers along with the developing paired cerebral ganglia characteristic of an adult mollusk. Pediveligers have the pleural ganglia connected to the pedal ganglia via the pedal nerve cords and to the visceral ganglia via the lateral nerve cords. We have found a number of structures of the peripheral nervous system whose presence varies between pediveligers of different species. Mactromeris, Callista, and Pododesmus have 5-HT-immunopositive stomatogastric neurons, whereas the Yesso and Farrer's scallops have an FMRFamide-immunopositive enteric nervous system. The innervation of the anterior part of the velum is connected to a system of the apical organ and cerebral ganglia, and the innervation of the posterior part is connected to the visceral ganglia. Most differences in the structure of the peripheral elements of the nervous system are species-specific and weakly depend on the ecological niche that pediveligers occupy.

Kynurenic Acid Levels and Kynurenine Aminotransferase I, II and III Activities in Ganglia, Heart and Liver of Snail Helix Pomatia.

Kynurenic acid (KYNA), a tryptophan metabolite along the kynurenine pathway, is an endogenous antagonist of glutamate ionotropic excitatory amino acid (EAA) receptors and the α7 nicotinic acetylcholine receptor (nAChR). The involvement of KYNA in various pathological conditions and during the aging process is significant. KYNA synthesis from L-kynurenine (L-KYN), through the action of several kynurenine aminotransferases (KATs), is present in the central nervous system (CNS) and periphery of mammals. We were interested in investigating the ability of the brain and peripheral organs of Helix pomatia snails to synthesize KYNA, in an in vitro study. In comparative studies between rat and snail, we looked for the synthesis of KYNA in the liver. We then looked for an effect of age on KYNA synthesis. Ten shell parameters of the Helix pomatia snail were used to establish an Age Rating Scale (ARS), i.e. body weight, shell weight, shell length, width and height, shell opening length and width, lip width, number of shell turns and external shell growth rings. An age of the snails was determined according to the ARS and the snails were divided into three groups, i.e. young, middle and old age. Homogenates of dissected regions, i.e. cerebral ganglia (CG), subpharyngeal ganglia (SG) consisting of pedal, visceral and pleural ganglia, heart and liver, were examined. KYNA was measured by high performance liquid chromatography (HPLC) and KAT activities were measured by an enzymatic method. With respect to ARS, an evaluation of the age of the snails between young (1-2 years), middle (5-7 years) and old (9-13 years) showed significant differences (p<0.001). Analysis of KYNA levels in different snail tissues, i.e. CG, SG, heart and liver, showed an occurrence in the low femtomolar range. Marked and significant increases of KYNA were found in the liver of middle and old age groups. In the SG, KYNA decreased significantly with age. There were no differences in KYNA levels between groups in CG and heart. The lowest KAT activity was found in CG and SG (5 pmol/mg/h), while in heart and liver the values were visibly higher (between 8 and 80 pmol/mg/h). Only in the liver, and exceptionally only for KAT I, the activity increased significantly with age, i.e. up to 14 years. No age-related changes in KAT I, II and III activities were found in CG and SG. Snail liver shows a different pattern of KAT activities compared to the rat liver. Regions of the CNS and periphery of the snail Helix pomatia are able to synthesize KYNA due to KAT activities. In the snail liver, KAT I activity increased with age. Notably, there was no age-related increase in KAT activities in the heart and especially in the CNS of Helix pomatia, indicating significant differences from mammals. A moderate KYNA metabolism in the Helix pomatia snail in the periods studied, up to 14 years, could be a physiological phenomenon that protects organs from possible functional insufficiency due to high KYNA levels, as has been suggested. It is reasonable to search for the factor(s) that could regulate the concentration of KYNA in the body of the snail.

Neurogenesis of the scallop Azumapecten farreri: from the first larval sensory neurons to the definitive nervous system of juveniles

BackgroundScallops are among the best-studied bivalve mollusks. However, adult nervous system and neurogenesis studies of scallops are limited. Here, we studied the localization of neurotransmitters (serotonin/5-HT, FMRFamide, catecholamines) in adult ganglia and larvae of Azumapecten farreri using histochemical and immunohistochemical methods.ResultsWe found peptide FMRFamide in all adult scallop ganglia, whereas 5-HT-like immunoreactive (lir) somata were exclusively detected in the cerebropleural, pedal, and accessory ganglia. Scallop larval neurogenesis starts with the emergence of the 5-HT-lir neurons, which are part of the apical organ (AO) at the early veliger stage. Near the AO, paired anlagen of cerebral ganglion (CG) developed. 5-HT-lir neurites of the CG innervate the velum, ventral, and dorsal parts of the larva at the late veliger stage. Scallop pediveligers possess 5-HT-lir CG, pleural ganglia, and immunopositive signals in the developing enteric nervous system. FMRFamide-lir is first detected in dorsal, ventral, and AO cells of early veligers. Later, FMRFamide-lir extends to the visceral nervous cord, all ganglia, as well as in the enteric nervous system in pediveligers. Catecholaminergic neurons are detected near the larval mouth, in the vellum, and in the stomach in veligers.ConclusionsWe described the distribution of neurotransmitters of the ganglia in adult scallops and the larval neurodevelopment in A. farreri. Immunostaining of neurotransmitters showed that the gross anatomy of adult scallop ganglia, in general, is similar to that in other bivalves, but complicated by the complexity of the structure of the ganglia and the appearance of additional ganglia not described in other molluscs. A comparison of larval neuromorphology suggests that 5-HT-lir structures are more conservative than FMRF-lir structures in Bivalvia. Notably, the latter are much more distributed in scallop A. farreri larvae than in other studied bivalves.

The Distribution and Possible Roles of Small Cardioactive Peptide in the Nudibranch Melibe leonina.

SynopsisThe neuropeptide small cardioactive peptide (SCP) plays an integrative role in exciting various motor programs involved in feeding and locomotion in a number of gastropod species. In this study, immunohistochemistry, using monoclonal antibodies against SCPB, was used to localize SCPB-like-immunoreactive neurons in the central nervous system, and map their connections to various tissues, in the nudibranch, Melibe leonina. Approximately 28–36 SCPB-like-immunoreactive neurons were identified in the M. leonina brain, as well as one large neuron in each of the buccal ganglia. The neuropil of the pedal ganglia contained the most SCPB-like-immunoreactive varicosities, although only a small portion of these were due to SCPB-like-immunoreactive neurons in the same ganglion. This suggests that much of the SCPB-like immunoreactivity in the neuropil of the pedal ganglia was from neurons in other ganglia that projected through the pedal–pedal connectives or the connectives from the cerebral and pleural ganglia. We also observed extensive SCPB innervation along the length of the esophagus. Therefore, we investigated the impact of SCPB on locomotion in intact animals, as well as peristaltic contractions of the isolated esophagus. Injection of intact animals with SCPB at night led to a significant increase in crawling and swimming, compared to control animals injected with saline. Furthermore, perfusion of isolated brains with SCPB initiated expression of the swim motor program. Application of SCPB to the isolated quiescent esophagus initiated rhythmic peristaltic contractions, and this occurred in preparations both with and without the buccal ganglia being attached. All these data, taken together, suggest that SCPB could be released at night to arouse animals and enhance the expression of both feeding and swimming motor programs in M. leonina.

Phenotypic features of Helicina variabilis (Gastropoda: Neritimorpha) from Minas Gerais, Brazil

Helicina variabilis Wagner, 1827 (Neritimorpha, Helicinidae) is redescribed based on a sample collected in Nanuque, northern Minas Gerais, Brazil. The species description, previously based only on the shell, is expanded to the phenotypic features. The study revealed absorption of the internal shell whorls; a diaphragm muscle connected to the floor of the pallial cavity; a monoaulic pallial oviduct, with the female genital aperture inside the anal aperture, and the lack of a seminal receptacle and provaginal sac; and the pleural ganglia of the nerve ring connected with each other. The significance of these findings is discussed in the light of current taxonomic and phylogenetic knowledge.

Transcriptional correlates of memory maintenance following long-term sensitization of Aplysia californica.

We characterized the transcriptional response accompanying maintenance of long-term sensitization (LTS) memory in the pleural ganglia of Aplysia californica using microarray (N = 8) and qPCR (N = 11 additional samples). We found that 24 h after memory induction there is strong regulation of 1198 transcripts (748 up and 450 down) in a pattern that is almost completely distinct from what is observed during memory encoding (1 h after training). There is widespread up-regulation of transcripts related to all levels of protein production, from transcription (e.g., subunits of transcription initiation factors) to translation (e.g., subunits of eIF1, eIF2, eIF3, eIF4, eIF5, and eIF2B) to activation of components of the unfolded protein response (e.g., CREB3/Luman, BiP, AATF). In addition, there are widespread changes in transcripts related to cytoskeleton function, synaptic targeting, synaptic function, neurotransmitter regulation, and neuronal signaling. Many of the transcripts identified have previously been linked to memory and plasticity (e.g., Egr, menin, TOB1, IGF2 mRNA binding protein 1/ZBP-1), though the majority are novel and/or uncharacterized. Interestingly, there is regulation that could contribute to metaplasticity potentially opposing or even eroding LTS memory (down-regulation of adenylate cyclase and a putative serotonin receptor, up-regulation of FMRFa and a FMRFa receptor). This study reveals that maintenance of a “simple” nonassociative memory is accompanied by an astonishingly complex transcriptional response.

Specific Expression of Aplysia Phosphodiesterase 4 in Bag Cells Revealed by in situ Hybridization Analysis.

Phosphodiesterases (PDEs) play a key role in the regulation of cyclic adenosine monophosphate (cAMP), which in turn mediates various cellular functions including learning and memory. We previously cloned and characterized three PDE4 isoforms (ApPDE4) from Aplysia kurodai. Using reverse transcription polymerase chain reaction (RT-PCR), we found that ApPDE4 isoforms are primarily expressed in the central nervous system. However, the detailed distribution of ApPDE4 mRNA in Aplysia individual ganglions was not evident. In this study, to determine the distribution of ApPDE4 mRNAs in Aplysia ganglions, we performed in situ hybridization (ISH) using a probe targeting ApPDE4, including the PDE catalytic domain. Interestingly, we found the strongest ISH-positive signals in the symmetrical bag cell clusters of the abdominal ganglion. The R2, R14, L7, L2 and L11 neurons in the abdominal ganglion, LP1 neuron in pleural ganglion, and metacerebral (MCC) neurons were ISH-positive. Mechanosensory neurons of the sensory cluster were also stained on the ventral aspect of the right and left pleural ganglia. Taken together, we found the detailed distribution of ApPDE4 mRNA in Aplysia ganglion and support their roles in serotonin (5-HT)-induced synaptic facilitation of Aplysia mechanosensory neurons.

Immediate and persistent transcriptional correlates of long-term sensitization training at different CNS loci in Aplysia californica.

Repeated noxious stimulation produces long-term sensitization of defensive withdrawal reflexes in Aplysia californica, a form of long-term memory that requires changes in both transcription and translation. Previous work has identified 10 transcripts which are rapidly up-regulated after long-term sensitization training in the pleural ganglia. Here we use quantitative PCR to begin examining how these transcriptional changes are expressed in different CNS loci related to defensive withdrawal reflexes at 1 and 24 hours after long-term sensitization training. Specifically, we sample from a) the sensory wedge of the pleural ganglia, which exclusively contains the VC nociceptor cell bodies that help mediate input to defensive withdrawal circuits, b) the remaining pleural ganglia, which contain withdrawal interneurons, and c) the pedal ganglia, which contain many motor neurons. Results from the VC cluster show different temporal patterns of regulation: 1) rapid but transient up-regulation of Aplysia homologs of C/EBP, C/EBPγ, and CREB1, 2) delayed but sustained up-regulation of BiP, Tolloid/BMP-1, and sensorin, 3) rapid and sustained up-regulation of Egr, GlyT2, VPS36, and an uncharacterized protein (LOC101862095), and 4) an unexpected lack of regulation of Aplysia homologs of calmodulin (CaM) and reductase-related protein (RRP). Changes in the remaining pleural ganglia mirror those found in the VC cluster at 1 hour but with an attenuated level of regulation. Because these samples had almost no expression of the VC-specific transcript sensorin, our data suggests that sensitization training likely induces transcriptional changes in either defensive withdrawal interneurons or neurons unrelated to defensive withdrawal. In the pedal ganglia, we observed only a rapid but transient increase in Egr expression, indicating that long-term sensitization training is likely to induce transcriptional changes in motor neurons but raising the possibility of different transcriptional endpoints in this cell type.

Localization and functional characterization of a novel adipokinetic hormone in the mollusk, Aplysia californica.

Increasing evidence suggests that gonadotropin-releasing hormone (GnRH), corazonin, adipokinetic hormone (AKH), and red pigment-concentrating hormone all share common ancestry to form a GnRH superfamily. Despite the wide presence of these peptides in protostomes, their biological effects remain poorly characterized in many taxa. This study had three goals. First, we cloned the full-length sequence of a novel AKH, termed Aplysia-AKH, and examined its distribution in an opisthobranch mollusk, Aplysia californica. Second, we investigated in vivo biological effects of Aplysia-AKH. Lastly, we compared the effects of Aplysia-AKH to a related A. californica peptide, Aplysia-GnRH. Results suggest that Aplysia-AKH mRNA and peptide are localized exclusively in central tissues, with abdominal, cerebral, and pleural ganglia being the primary sites of Aplysia-AKH production. However, Aplysia-AKH-positive fibers were found in all central ganglia, suggesting diverse neuromodulatory roles. Injections of A. californica with Aplysia-AKH significantly inhibited feeding, reduced body mass, increased excretion of feces, and reduced gonadal mass and oocyte diameter. The in vivo effects of Aplysia-AKH differed substantially from Aplysia-GnRH. Overall, the distribution and biological effects of Aplysia-AKH suggest it has diverged functionally from Aplysia-GnRH over the course of evolution. Further, that both Aplysia-AKH and Aplysia-GnRH failed to activate reproduction suggest the critical role of GnRH as a reproductive activator may be a phenomenon unique to vertebrates.

Characterization of the rapid transcriptional response to long-term sensitization training in Aplysia californica

We used a custom-designed microarray and quantitative PCR to characterize the rapid transcriptional response to long-term sensitization training in the marine mollusk Aplysia californica. Aplysia were exposed to repeated noxious shocks to one side of the body, a procedure known to induce a long-lasting, transcription-dependent increase in reflex responsiveness that is restricted to the side of training. One hour after training, pleural ganglia from the trained and untrained sides of the body were harvested; these ganglia contain the sensory nociceptors which help mediate the expression of long-term sensitization memory. Microarray analysis from 8 biological replicates suggests that long-term sensitization training rapidly regulates at least 81 transcripts. We used qPCR to test a subset of these transcripts and found that 83% were confirmed in the same samples, and 86% of these were again confirmed in an independent sample. Thus, our new microarray design shows strong convergent and predictive validity for analyzing the transcriptional correlates of memory in Aplysia. Fully validated transcripts include some previously identified as regulated in this paradigm (ApC/EBP and ApEgr) but also include novel findings. Specifically, we show that long-term sensitization training rapidly up-regulates the expression of transcripts which may encode Aplysia homologs of a C/EBPγ transcription factor, a glycine transporter (GlyT2), and a vacuolar-protein-sorting-associated protein (VPS36).

Mercuric chloride-induced Gastrin/Cholecystokinin 8 immunoreactivity in the central nervous system of the terrestrial slug Semperula maculata: an immunohistochemical study

We measured the immunoreactivity of the neuropeptide gastrin cholecystokinin 8 (gastrin/CCK 8) in neurons of the terrestrial slug Semperula maculata following acute treatment with mercuric chloride (HgCl2). The distribution of gastrin/CCK 8 was analyzed in neurons of different regions, specifically from cerebral ganglia (procerebrum (pro-c), mesocerebrum (meso-c) and metacerebrum (meta-c). In the control group, neurons of pedal, pleural, parietal and visceral ganglia showed positive immunoreactivity using vertebrate antiserum against gastrin/CCK 8. Gastrin/CCK 8 immunoreactivity was also seen in the fibers and neuropil region of all ganglia. In the cerebral ganglion, 10, 12 and 8% of the neurons from pro-c, meso-c and meta-c, respectively, were stained with the antibody. The immunostaining was increased in neurons (giant, large, medium and small) after HgCl2 treatment. The treatment greatly increased the mucin content within the neurons. Exposure to HgCl2 enhanced gastrin immunoreactivity in the neurons and this increased with time. Results are discussed in the context of neuropathology in cerebral ganglia associated with the feeding behavior of Semperula maculata.

Proteomics reveals selective regulation of proteins in response to memory-related serotonin stimulation in Aplysia californica ganglia

The marine mollusk Aplysia californica (Aplysia) is a powerful model for learning and memory due to its minimalistic nervous system. Key proteins, identified to be regulated by the neurotransmitter serotonin in Aplysia, have been successfully translated to mammalian models of learning and memory. Based upon a recently published large-scale analysis of Aplysia proteomic data, the current study investigated the regulation of protein levels 24 and 48 h after treatment with serotonin in Aplysia ganglia using a 2-D gel electrophoresis approach. Protein spots were quantified and protein-level changes of selected proteins were verified by Western blotting. Among those were Rab GDP dissociation inhibitor alpha (RabGDIα), synaptotagmin-1 and deleted in azoospermia-associated protein (DAZAP-1) in cerebral ganglia, calreticulin, RabGDIα, DAZAP-1, heterogeneous nuclear ribonucleoprotein F (hnRNPF), RACK-1 and actin-depolymerizing factor (ADF) in pleural ganglia and DAZAP-1, hnRNPF and ADF in pedal ganglia. Protein identity of the majority of spots was confirmed by a gel-based mass spectrometrical method (FT-MS). Taken together, protein-level changes induced by the learning-related neurotransmitter serotonin in Aplysia ganglia are described and a role for the abovementioned proteins in synaptic plasticity is proposed.

The Serotoninergic Neuron System in the CNS of the Common Snail: Morphology, Ontogeny, Control of Behavior

We report here studies of the morphology of the serotoninergic neuron system, which modulates defensive behavior, in the CNS of the common snail. Only one neuron, Pd4, projects to the pleural and parietal ganglia. Stimulation of this neuron evokes the same effects as stimulation of the whole group of modulatory neurons. In juvenile animals, the number of serotoninergic neurons and the relative sizes of these neurons were smaller than in adult animals, which may underlie the age-related differences in defensive behavior.

Sacoglossa or Acochlidia? 3D reconstruction, molecular phylogeny and evolution of Aitengidae (Gastropoda: Heterobranchia)

The amphibious ‘bug-eating slug’ Aiteng ater Swennen & Buatip, 2009 shows a worm-like, compact body shape lacking any cephalic tentacles or body processes. Anatomically it has been described as showing an unusual mix of sacoglossan and acochlidian characters, thus the systematic affinities are uncertain. The species is redescribed here with an integrative microanatomical and molecular approach. All major organ systems were three-dimensionally reconstructed from serial histological sections using AMIRA software. Aiteng ater has a prepharyngeal nerve ring with separate cerebral and pleural ganglia rather than cerebro-pleural ganglia, and no sacoglossan-like ascus is detectable histologically. The radula is triseriate rather than uniseriate, showing one lateral tooth on each side of the rhachidian tooth. A well-developed two-chambered heart is present. The vas deferens in A. ater splits off distal to the female glands. The intestine is short and opens into a small mantle cavity. Long cavities in the connective tissue are remains of dissolved calcareous spicules. Only a few characters thus remain to support a closer relationship of A. ater to Sacoglossa, i.e. the Gascoignella-like body shape lacking cephalic tentacles, the presence of an elysiid-like system of dorsal vessels, and an albumen gland consisting of follicles. Additionally we describe in microanatomical detail an equally small and vermiform new aitengid species from Japan. Aiteng mysticus n. sp. differs from A. ater in habitat, body size and colour, central nervous system and presence of a kidney. Both aitengid species resemble acochlidians in the retractibility of the head, by possessing calcareous spicules, a prepharyngeal nerve ring with separated cerebral and pleural ganglia, a triseriate radula with an ascending and descending limb, but without sacoglossan-like ascus, and a special diaulic reproductive system. The prominent rhachidian tooth of Aitengidae, which is used to pierce insects and pupae in A. ater, and the large, laterally situated eyes closely resemble the anatomy of members of the limnic Acochlidiidae. The acochlidian nature of Aiteng is strongly indicated by our molecular analysis, in which it forms a basal hedylopsacean offshoot or the sister clade to limnic Acochlidiidae and brackish or marine Pseudunelidae within Hedylopsacea. Such a topology would, however, imply that Aitengidae have lost the most characteristic acochlidian apomorphy, the subdivision of the body into a headfoot complex and a free, elongated visceral hump. Also, the absence of cephalic tentacles gives the Aitengidae an appearance that is very different to other, strictly aquatic Acochlidia. Differences of the external morphology and the internal anatomy are discussed in the light of a habitat shift of Aitengidae within the Acochlidia.

Morphology and Histology of the Central Nervous System and Ultrastructure of Neurosecretory Cells of Female Spotted Babylon,Babylonia areolata

ABSTRACT The nervous system of the female spotted Babylon, Babylonia areolata Link 1807, consists of left and right pairs of buccal ganglia, pedal ganglia, cerebral ganglia, pleural ganglia, and parietal ganglia, and a single left-side visceral ganglion. Each ganglion has an outer cortex and an inner medulla. The outer cortex contains three cell types: neurosecretory (NS) cells, neurons (NR), and neuroglia (NG). The medulla consists of NG and nerve fibers. The ultrastructural studies of the NS cells in each ganglion demonstrate that the buccal, pleural, and pedal ganglia contain neurosecretory granules (NSg) type I and II cells. The NS cells in the cerebral ganglia are NSg types I, II, and III, whereas in the parietal ganglia their NSg are types I, II, III, and IV. Furthermore, the NS cells of the visceral ganglion are of NSg types I and III. The different structures of NSg in the NS cells in the ganglia indicate that they may produce different neurosecretions.

The tail-elicited tail withdrawal reflex of Aplysia is mediated centrally at tail sensory-motor synapses and exhibits sensitization across multiple temporal domains

The defensive withdrawal reflexes of Aplysia californica have provided powerful behavioral systems for studying the cellular and molecular basis of memory formation. Among these reflexes the tail-elicited tail withdrawal reflex (T-TWR) has been especially useful. In vitro studies examining the monosynaptic circuit for the T-TWR, the tail sensory-motor (SN-MN) synapses, have identified the induction requirements and molecular basis of different temporal phases of synaptic facilitation that underlie sensitization in this system. They have also permitted more recent studies elucidating the role of synaptic and nuclear signaling during synaptic facilitation. Here we report the development of a novel, compartmentalized semi-intact T-TWR preparation that allows examination of the unique contributions of processing in the SN somatic compartment (the pleural ganglion) and the SN-MN synaptic compartment (the pedal ganglion) during the induction of sensitization. Using this preparation we find that the T-TWR is mediated entirely by central connections in the synaptic compartment. Moreover, the reflex is stably expressed for at least 24 h, and can be modified by tail shocks that induce sensitization across multiple temporal domains, as well as direct application of the modulatory neurotransmitter serotonin. This preparation now provides an experimentally powerful system in which to directly examine the unique and combined roles of synaptic and nuclear signaling in different temporal domains of memory formation.

3D-anatomy of a new tropical Peruvian nudibranch gastropod species, Corambe mancorensis, and novel hypotheses on dorid gill ontogeny and evolution

Nudibranch molluscs of the genus Corambe differ from most other Doridoidea by having ventral rather than dorsal anus and gills. Because of these and other features, such as separate cerebral and pleural ganglia, corambids have been considered as an archaic or enigmatic group. The first tropical eastern Pacific Corambe species is described in morphological and some histological detail. Selected organs such as circulatory and central nervous features are reconstructed from serial semithin histological slides and visualized in three dimensions using Amira software. Anatomical findings include two separate ganglia on the visceral loop and an additional ganglion on the right side of the body that is connected to the pedal ganglion. Corambe mancorensis n. sp. is dorsoventrally depressed, has an oval, fleshy notum covered with a cuticle, and has a wide posterior medial notch that can be closed completely by unique lobules. Gills are arranged in an unusual horseshoe-like manner including both phanerobranch anal (=medial) gills and corambid lateroventral gill rows, and are connected to the atrium by a complex vessel system. The three medial gills arise from a posterodorsal gill cavity within the notal notch, similar to the case in Corambe evelinae Marcus, 1958. By scanning electron microscopy a vestigial gill cavity is also detectable in C. pacifica MacFarland & O'Donoghue, 1929, but here it is situated ventrally. Our new information on adult corambids is compared with new and published ontogenetic data on phanerobranch and cryptobranch dorids, to contribute to a novel interpretation of the ontogeny of dorid mantle and gill complexes. The progenetic evolution of corambids ‘recapitulates’ early juvenile dorid stages – turning Haeckel's Law upside down.

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.

Distribution of NADPH-diaphorase activity in the central nervous system of the young and adult land snail Megalobulimus abbreviatus

Nitric oxide (NO) is a gas produced through the action of nitric oxide synthase that acts as a neurotransmitter in the central nervous system (CNS) of adult gastropod mollusks. There are no known reports of the presence of NOS-containing neurons and glial cells in young and adult Megalobulimus abbreviatus. Therefore, NADPH-d histochemistry was employed to map the nitrergic distribution in the CNS of young and adult snails in an attempt to identify any transient enzymatic activity in the developing CNS. Reaction was observed in neurons and fibers in all CNS ganglia of both age groups, but in the pedal and cerebral ganglia, positive neurons were more intense than in other ganglia, forming clusters symmetrically located in both paired ganglia. However, neuronal NADPH-d activity in the mesocerebrum and pleural ganglia decreased from young to adult animals. In both age groups, positive glial cells were located beneath the ganglionic capsule, forming a network and surrounding the neuronal somata. The trophospongium of large and giant neurons was only visualized in young animals. Our results indicate the presence of a nitrergic signaling system in young and adult M. abbreviatus, and the probable involvement of glial cells in NO production.

Changes in d-aspartate ion currents in the Aplysia nervous system with aging

d-Aspartate (D-Asp) can substitute for l-glutamate (L-Glu) at excitatory Glu receptors, and occurs as free D-Asp in the mammalian brain. D-Asp electrophysiological responses were studied as a potential correlate of aging in the California sea hare, Aplysia californica. Whole cell voltage- and current clamp measurements were made from primary neuron cultures of the pleural ganglion (PVC) and buccal ganglion S cluster (BSC) in 3 egg cohorts at sexual maturity and senescence. D-Asp activated an inward current at the hyperpolarized voltage of − 70 mV, where molluscan NMDA receptors open free of constitutive block by Mg 2+. Half of the cells responded to both D-Asp and L-Glu while the remainder responded only to D-Asp or L-Glu, suggesting that D-Asp activated non-Glu channels in a subpopulation of these cells. The frequency of D-Asp-induced currents and their density were significantly decreased in senescent PVC cells but not in senescent BSC cells. These changes in sensory neurons of the tail predict functional deficits that may contribute to an overall decline in reflexive movement in aged Aplysia.