The neuropeptide SMYamide, a SIFamide paralog, is expressed by salivary gland innervating neurons in the American cockroach and likely functions as a hormone

The SMYamide genes are paralogs of the SIFamide genes and code for neuropeptides that are structurally similar to SIFamide. In the American cockroach, Periplanea americana, the SMYamide gene is specifically expressed in the SN2 neurons that innervate the salivary glands and are known to produce action potentials during feeding. The SN2 axon terminals surround rather than directly innervate the salivary gland acini. Therefore one may expect that on activation of these neurons significant amounts of SMYamide will be released into the hemolymph, thus suggesting that SMYamide may also have a hormonal function. In the Periplaneta genome there are two putative SIFamide receptors and these are both expressed not only in the central nervous system and the salivary gland, but also in the gonads and other peripheral tissues. This reinforces the hypothesis that SMYamide also has an endocrine function in this species.

Role of neuroparsin 1 in vitellogenesis in the mud crab, Scylla paramamosain

Neuroparsin (NP) is an important neuropeptide in invertebrates. It is well-known that NP displays multiple biological activities, including antidiuretic and inhibition of vitellogenesis in insects. However, the information about its effect in crustaceans is scarce. In this study, the sequence of Sp-NP1 was selected from the transcriptome database from the mud crab, Scylla paramamosain. Sequence analyses indicate that the Sp-NP1 amino acid (AA) sequences consist of a 27 AA signal peptide and a 74 AA mature peptide, which contains 12 cysteine residues. qRT-PCR analysis has revealed that the expressions of Sp-NP1 gene are high in the nervous tissues and extremely low in the ovary and hepatopancreas. In situ hybridization has shown that the positive signals are localized in cell cluster 6 of protocerebrum and cell clusters 10 and 11 of deutocerebrum. The presence of Sp-NP1 in the haemolymph has been detected in S. paramamosain through western blot, which indicates that Sp-NP1 serves as an endocrine factor in the regulation of physiological activities. In vitro experiments have further shown that the mRNA level of vitellogenin in the hepatopancreas notably decreases following administration of recombinant Sp-NP1, while the mRNA level of vitellogenin receptor and cyclin B in the ovary shows no significant differences. Collectively, Sp-NP1 possibly can inhibit the production of vitellogenin in the hepatopancreas and has no direct effect on the ovary in S. paramamosain.

Over-expression of Hsp83 in grossly depleted hsrω lncRNA background causes synthetic lethality and l(2)gl phenocopy in Drosophila

We examined interactions between the 83 kDa heat-shock protein (Hsp83) and hsrω long noncoding RNAs (lncRNAs) in hsrω⁶⁶ Hsp90GFP homozygotes, which almost completely lack hsrω lncRNAs but over-express Hsp83. All +/+; hsrω⁶⁶ Hsp90GFP progeny died before the third instar. Rare Sp/CyO; hsrω⁶⁶ Hsp90GFP reached the third instar stage but phenocopied l(2)gl mutants, becoming progressively bulbous and transparent with enlarged brain and died after prolonged larval life. Additionally, ventral ganglia too were elongated. However, hsrω⁶⁶ Hsp90GFP/TM6B heterozygotes, carrying +/+ or Sp/CyO second chromosomes, developed normally. Total RNA sequencing (+/+, +/+; hsrω66/hsrω⁶⁶, Sp/CyO; hsrω⁶⁶/ hsrω⁶⁶, +/+; Hsp90GFP/Hsp90GFP and Sp/CyO; hsrω66 Hsp90GFP/hsrω66 Hsp90GFP late third instar larvae) revealed similar effects on many genes in hsrω66 and Hsp90GFP homozygotes. Besides additive effect on many of them, numerous additional genes were affected in Sp/CyO; hsrω66 Hsp90GFP larvae, with l(2)gl and several genes regulating the central nervous system being highly down-regulated in surviving Sp/CyO; hsrω66 Hsp90GFP larvae, but not in hsrω⁶⁶ or Hsp90GFP single mutants. Hsp83 and several omega speckle-associated hnRNPs were bioinformatically found to potentially bind with these gene promoters and transcripts. Since Hsp83 and hnRNPs are also known to interact, elevated Hsp83 in an altered background of hnRNP distribution and dynamics, due to near absence of hsrω lncRNAs and omega speckles, can severely perturb regulatory circuits with unexpected consequences, including down-regulation of tumoursuppressor genes such as l(2)gl.

Identification of Immediate Early Genes in the Nervous System of Snail Helix lucorum

Immediate early genes (IEGs) are useful markers of neuronal activation and essential components of neuronal response. While studies of gastropods have provided many insights into the basic learning and memory mechanisms, the genome-wide assessment of IEGs has been mainly restricted to vertebrates. In this study, we identified IEGs in the terrestrial snail Helix lucorum In the absence of the genome, we conducted de novo transcriptome assembly using reads with short and intermediate lengths cumulatively covering more than 98 billion nucleotides. Based on this assembly, we identified 37 proteins corresponding to contigs differentially expressed (DE) in either the parietal ganglia (PaG) or two giant interneurons located within the PaG of the snail in response to the neuronal stimulation. These proteins included homologues of well-known mammalian IEGs, such as c-jun/jund, C/EBP, c-fos/fosl2, and Egr1, as well as homologues of genes not yet implicated in the neuronal response.

Transcriptional changes before and after forgetting of a long-term sensitization memory in Aplysia californica

Most long-term memories are forgotten, becoming progressively less likely to be recalled. Still, some memory fragments may persist, as savings memory (easier relearning) can be detected long after recall has become impossible. What happens to a memory trace during forgetting that makes it inaccessible for recall and yet still effective to spark easier re-learning? We are addressing this question by tracking the transcriptional changes that accompany learning and then forgetting of a long-term sensitization memory in the tail-elicited siphon withdrawal reflex of Aplysia californica. First, we tracked savings memory. We found that even though recall of sensitization fades completely within 1 week of training, savings memory is still detectable at 2 weeks post training. Next, we tracked the time-course of regulation of 11 transcripts we previously identified as potentially being regulated after recall has become impossible. Remarkably, 3 transcripts still show strong regulation 2 weeks after training and an additional 4 are regulated for at least 1 week. These long-lasting changes in gene expression always begin early in the memory process, within 1 day of training. We present a synthesis of our results tracking gene expression changes accompanying sensitization and provide a testable model of how sensitization memory is forgotten.

Three members of a peptide family are differentially distributed and elicit differential state-dependent responses in a pattern generator-effector system

C-type allatostatins (AST-Cs) are pleiotropic neuropeptides that are broadly conserved within arthropods; the presence of three AST-C isoforms, encoded by paralog genes, is common. However, these peptides are hypothesized to act through a single receptor, thereby exerting similar bioactivities within each species. We investigated this hypothesis in the American lobster, Homarus americanus, mapping the distributions of AST-C isoforms within relevant regions of the nervous system and digestive tract, and comparing their modulatory influences on the cardiac neuromuscular system. Immunohistochemistry showed that in the pericardial organ, a neuroendocrine release site, AST-C I and/or III and AST-C II are contained within distinct populations of release terminals. Moreover, AST-C I/III-like immunoreactivity was seen in midgut epithelial endocrine cells and the cardiac ganglion (CG), whereas AST-C II-like immunoreactivity was not seen in these tissues. These data suggest that AST-C I and/or III can modulate the CG both locally and hormonally; AST-C II likely acts on the CG solely as a hormonal modulator. Physiological studies demonstrated that all three AST-C isoforms can exert differential effects, including both increases and decreases, on contraction amplitude and frequency when perfused through the heart. However, in contrast to many state-dependent modulatory changes, the changes in contraction amplitude and frequency elicited by the AST-Cs were not functions of the baseline parameters. The responses to AST-C I and III, neither of which is COOH-terminally amidated, are more similar to one another than they are to the responses elicited by AST-C II, which is COOH-terminally amidated. These results suggest that the three AST-C isoforms are differentially distributed in the lobster nervous system/midgut and can elicit distinct behaviors from the cardiac neuromuscular system, with particular structural features, e.g., COOH-terminal amidation, likely important in determining the effects of the peptides. NEW & NOTEWORTHY Multiple isoforms of many peptides exert similar effects on neural circuits. In this study we show that each of the three isoforms of C-type allatostatin (AST-C) can exert differential effects, including both increases and decreases in contraction amplitude and frequency, on the lobster cardiac neuromuscular system. The distribution of effects elicited by the nonamidated isoforms AST-C I and III are more similar to one another than to the effects of the amidated AST-C II.

Non-amidated and amidated members of the C-type allatostatin (AST-C) family are differentially distributed in the stomatogastric nervous system of the American lobster, Homarus americanus

The crustacean stomatogastric nervous system (STNS) is a well-known model for investigating neuropeptidergic control of rhythmic behavior. Among the peptides known to modulate the STNS are the C-type allatostatins (AST-Cs). In the lobster, Homarus americanus, three AST-Cs are known. Two of these, pQIRYHQCYFNPISCF (AST-C I) and GNGDGRLYWRCYFNAVSCF (AST-C III), have non-amidated C-termini, while the third, SYWKQCAFNAVSCFamide (AST-C II), is C-terminally amidated. Here, antibodies were generated against one of the non-amidated peptides (AST-C I) and against the amidated isoform (AST-C II). Specificity tests show that the AST-C I antibody cross-reacts with both AST-C I and AST-C III, but not AST-C II; the AST-C II antibody does not cross-react with either non-amidated peptide. Wholemount immunohistochemistry shows that both subclasses (non-amidated and amidated) of AST-C are distributed throughout the lobster STNS. Specifically, the antibody that cross-reacts with the two non-amidated peptides labels neuropil in the CoGs and the stomatogastric ganglion (STG), axons in the superior esophageal (son) and stomatogastric (stn) nerves, and ~ 14 somata in each commissural ganglion (CoG). The AST-C II-specific antibody labels neuropil in the CoGs, STG and at the junction of the sons and stn, axons in the sons and stn, ~ 42 somata in each CoG, and two somata in the STG. Double immunolabeling shows that, except for one soma in each CoG, the non-amidated and amidated peptides are present in distinct sets of neuronal profiles. The differential distributions of the two AST-C subclasses suggest that the two peptide groups are likely to serve different modulatory roles in the lobster STNS.

Savings memory is accompanied by transcriptional changes that persist beyond the decay of recall

Most long-term memories are forgotten. What happens, then, to the changes in neuronal gene expression that were initially required to encode and maintain the memory? Here we show that the decay of recall for long-term sensitization memory in Aplysia is accompanied both by a form of savings memory (easier relearning) and by persistent transcriptional regulation. A behavioral experiment (N = 14) shows that sensitization training produces a robust long-term sensitization memory, but that recall fades completely within 1 wk. This apparent forgetting, though, is belied by persistent savings memory, as we found that a weak reminder protocol reinstates a long-term sensitization memory only on the previously trained side of the body. Using microarray (N = 8 biological replicates), we found that transcriptional regulation largely decays along with recall. Of the transcripts known to be regulated 1 d after training, 98% (1172/1198) are no longer significantly regulated 7 d after training. Still, there is a small set of transcripts which remain strongly regulated even when recall is absent. Using qPCR (N = 11 additional biological replicates) we confirmed that these include the peptide transmitter FMRFamide, a transcript encoding a putative homolog of spectrin beta chain (Genbank: EB255259) , a transcript encoding a protein with a predicted EF-hand calcium-binding domain (Genbank: EB257711), and eight uncharacterized transcripts. To our knowledge, this is the first work to show that transcriptional changes evoked by learning can outlast recall. The small set of transcriptional changes that persist could mediate the rapid relearning of the memory (savings), or the decay of recall, or both, or neither.

Neuropeptides encoded within a neural transcriptome of the giant triton snail Charonia tritonis, a Crown-of-Thorns Starfish predator

Neuropeptides represent a diverse class of signaling molecules originating from neural tissues. These chemical modulators orchestrate complex physiological events including those associated with growth and reproduction. De novo transcriptome sequencing of a cerebral ganglion library of the endangered giant triton snail (Charonia tritonis) was undertaken in an effort to identify key neuropeptides that control or influence its physiology. The giant triton snail is considered a primary predator of the corallivore Acanthaster planci (Crown-of-Thorns Starfish) that is responsible for a significant loss in coral cover on reefs in the Indo-Pacific. The transcriptome library was assembled into contigs, and then bioinformatic analysis was used to identify a repertoire of 38 giant triton snail neuropeptide precursor genes, and various isoforms, that encode conserved molluscan neuropeptides. C. tritonis neuropeptides show overall precursor organisation consistent with those of other molluscs. These include those neuropeptides associated with mollusc reproduction such as the APGWamide, buccalin, conopressin, gonadotropin-releasing hormone (GnRH), NKY and egg-laying hormone. These data provide a foundation for further studies targeted towards the functional characterisation of neuropeptides to further understand aspects of the biology of the giant triton snail, such as elucidating its reproductive neuroendocrine pathway to allow the development of knowledge based captive breeding programs.

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.

Localization and functional analysis of the insect-specific RabX4 in the brain of Bombyx mori

Rab proteins are small monomeric GTPases/GTP-binding proteins, which form the largest branch of the Ras superfamily. The different Rab GTPases are localized to the cytosolic face of specific intracellular membranes, where they function as regulators of distinct steps in membrane trafficking. RabX4 is an insect-specific Rab protein that has no close homolog in vertebrates. There is little information about insect-specific Rab proteins. RabX4 was expressed in Escherichia coli and subsequently purified. Antibodies against Bombyx mori RabX4 were produced in rabbits for western immunoblotting and immunohistochemistry. Western blotting of neural tissues revealed a single band, at approximately 26 kD. RabX4-like immunohistochemical reactivity was restricted to neurons of the pars intercerebralis and dorsolateral protocerebrum in the brain. Further immunohistochemical analysis revealed that RabX4 colocalized with Rab6 and bombyxin in the corpus allatum, a neuronal organ that secretes neuropeptides synthesized in the brain into the hemolymph. RabX4 expression in the frontal ganglion, part of the insect stomatogastric nervous system that is found in most insect orders, was restricted to two neurons on the outer region and did not colocalize with allatotropin or Rab6. Furthermore, RNA interference of RabX4 decreased bombyxin expression levels in the brain. These findings suggest that RabX4 is involved in the neurosecretion of a secretory organ in Bombyx mori.

Genome-wide identification and expression profiling of the SOX gene family in a bivalve mollusc Patinopecten yessoensis

SOX family is composed of transcription factors that play vital roles in various developmental processes. Comprehensive understanding on evolution of the SOX family requires full characterization of SOX genes in different phyla. Mollusca is the second largest metazoan phylum, but till now, systematic investigation on the SOX family is still lacking in this phylum. In this study, we conducted genome-wide identification of the SOX family in Yesso scallop Patinopecten yessoensis and profiled their tissue distribution and temporal expression patterns in the ovaries and testes during gametogenesis. Seven SOX genes were identified, including SOXB1, B2, C, D, E, F and H, representing the first record in protostomes with SOX members identical to that proposed to exist in the last common ancestor of chordates. Genomic structure analysis identified relatively conserved exon-intron structures, accompanied by intron insertion. Quantitative real-time PCR analysis revealed possible involvement of scallop SOX in various functions, including neuro-sensory cell differentiation, hematopoiesis, myogenesis and gametogenesis. This study represents the first systematic characterization of SOX gene family in Mollusca. It will assist in a better understanding of the evolution and function of SOX family in metazoans.

Characterization, localization and temporal expression of crustacean hyperglycemic hormone (CHH) in the behaviorally rhythmic peracarid crustaceans, Eurydice pulchra (Leach) and Talitrus saltator (Montagu)

Crustacean hyperglycemic hormone (CHH) has been extensively studied in decapod crustaceans where it is known to exert pleiotropic effects, including regulation of blood glucose levels. Hyperglycemia in decapods seems to be temporally gated to coincide with periods of activity, under circadian clock control. Here, we used gene cloning, in situ hybridization and immunohistochemistry to describe the characterization and localization of CHH in two peracarid crustaceans, Eurydice pulchra and Talitrus saltator. We also exploited the robust behavioral rhythmicity of these species to test the hypothesis that CHH mRNA expression would resonate with their circatidal (12.4h) and circadian (24h) behavioral phenotypes. We show that both species express a single CHH transcript in the cerebral ganglia, encoding peptides featuring all expected, conserved characteristics of other CHHs. E. pulchra preproCHH is an amidated 73 amino acid peptide N-terminally flanked by a short, 18 amino acid precursor related peptide (CPRP) whilst the T. saltator prohormone is also amidated but 72 amino acids in length and has a 56 residue CPRP. The localization of both was mapped by immunohistochemistry to the protocerebrum with axon tracts leading to the sinus gland and into the tritocerebrum, with striking similarities to terrestrial isopod species. We substantiated the cellular position of CHH immunoreactive cells by in situ hybridization. Although both species showed robust activity rhythms, neither exhibited rhythmic transcriptional activity indicating that CHH transcription is not likely to be under clock control. These data make a contribution to the inventory of CHHs that is currently lacking for non-decapod species.

Cerebral ganglion ultrastructure and differential proteins revealed using proteomics in the aplysiid (Notarcus leachii cirrosus Stimpson) under cadmium and lead stress

Cadmium (Cd) and lead (Pb) are both highly toxic metals in environments. However the toxicological mechanism is not clear. In this study, the aplysiid, Notarcus leachii cirrosus Stimpson (NLCS) was subjected to Cd (NLCS-Cd) or Pb (NLCS-Pb). The cerebral ganglion of NLCS was investigated with a transmission electron microscope. Next the differential proteins were separated and identified using proteomic approaches. Eighteen protein spots in NLCS-Cd and seventeen protein spots in NLCS-Pb were observed to be significantly changed. These protein spots were further excised in gels and identified. A hypothetical pathway was drawn to show the correlation between the partially identified proteins. The results indicated that damage to the cerebral ganglion was follows: cell apoptosis, lysosomes proliferation, cytoskeleton disruption, and oxidative stress. These phenomena and data indicated potential biomarkers for evaluating the contamination levels of Cd and Pb. This study provided positive insights into the mechanisms of Cd and Pb toxicity.

Contribution of Drosophila TRPA1 to Metabolism

Transient receptor potential (TRP) cation channels are highly conserved in humans and insects. Some of these channels are expressed in internal organs and their functions remain incompletely understood. By direct knock-in of the GAL4 gene into the trpA1 locus in Drosophila, we identified the expression of this gene in the subesophageal ganglion (SOGs) region. In addition, the neurites present in the dorsal posterior region as well as the drosophila insulin-like peptide 2 (dILP2)-positive neurons send signals to the SOGs. The signal is sent to the crop, which is an enlarged organ of the esophagus and functions as a storage place for food in the digestive system. To systematically investigate the role of TRPA1 in metabolism, we applied non-targeted metabolite profiling analysis together with gas-chromatography/time-of-flight mass spectrometry, with an aim to identify a wide range of primary metabolites. We effectively captured distinctive metabolomic phenotypes and identified specific metabolic dysregulation triggered by TRPA1 mutation based on reconstructed metabolic network analysis. Primarily, the network analysis pinpointed the simultaneous down-regulation of intermediates in the methionine salvation pathway, in contrast to the synchronized up-regulation of a range of free fatty acids. The gene dosage-dependent dynamics of metabolite levels among wild-type, hetero- and homozygous mutants, and their coordinated metabolic modulation under multiple gene settings across five different genotypes confirmed the direct linkages of TRPA1 to metabolism.

Pan-neuronal imaging in roaming Caenorhabditis elegans

We present an imaging system for pan-neuronal recording in crawling Caenorhabditis elegans. A spinning disk confocal microscope, modified for automated tracking of the C. elegans head ganglia, simultaneously records the activity and position of ∼80 neurons that coexpress cytoplasmic calcium indicator GCaMP6s and nuclear localized red fluorescent protein at 10 volumes per second. We developed a behavioral analysis algorithm that maps the movements of the head ganglia to the animal's posture and locomotion. Image registration and analysis software automatically assigns an index to each nucleus and calculates the corresponding calcium signal. Neurons with highly stereotyped positions can be associated with unique indexes and subsequently identified using an atlas of the worm nervous system. To test our system, we analyzed the brainwide activity patterns of moving worms subjected to thermosensory inputs. We demonstrate that our setup is able to uncover representations of sensory input and motor output of individual neurons from brainwide dynamics. Our imaging setup and analysis pipeline should facilitate mapping circuits for sensory to motor transformation in transparent behaving animals such as C. elegans and Drosophila larva.

Characterization of GnRH-like peptides from the nerve ganglia of Yesso scallop, Patinopecten yessoensis

There is yet no firm experimental evidence that the evolutionary ancient gonadotropin-releasing hormone GnRH (i.e., GnRH1) also acts in invertebrate gametogenesis. The objective of this paper is to characterize candidate invGnRH peptides of Yesso scallop Patinopecten yessoensis (i.e., peptide identification, immunohistochemical localization, and immunoquantification) in order to reveal their bioactive form in bivalves. Using mass spectrometry (MS), we identified two invGnRH (py-GnRH) peptides from the scallop nerve ganglia: a precursor form of py-GnRH peptide (a non-amidated dodecapeptide; py-GnRH12aa-OH) and a mature py-GnRH peptide (an amidated undecapeptide; py-GnRH11aa-NH2). Immunohistochemical staining allowed the localization of both py-GnRH peptides in the neuronal cell bodies and fibers of the cerebral and pedal ganglia (CPG) and the visceral ganglion (VG). We found that the peptides showed a dimorphic distribution pattern. Notably, the broad distribution of mature py-GnRH in neuronal fibers elongating to peripheral organs suggests that it is multi-functional. Time-resolved fluorescent immunoassays (TR-FIA) enabled the quantification of each py-GnRH form in the single CPG or VG tissue obtained from one individual. In addition, we observed greater abundance of mature py-GnRH in VG compared with its level in CPG, suggesting that VG is the main producing organ of mature py-GnRH peptide and that py-GnRH may play a central regulatory role in neurons of scallops. Our study provides evidence, for the first time, for the presence of precursor and mature forms of invGnRH peptides in the nerve ganglia of an invertebrate.

[Heterochronies in the Formation of the Nervous and Digestive Systems in Early Postlarval Development of Opistobranch Mollusks: Organization of Basic Functional Systems of the Arctic Dorid Cadlina laevis]

For the first time using laser confocal microscopy and histochemical and immunocytochemical methods (detection of F-actine, catecholamines, acetylcholintransferase, substances of P and FM RFamide) in combination with classical histological methods and electron microscopy of total preparations, the general structure and regularities of formation of the main organs and the nervous, muscular, and digestive systems in early postlarval development (2 to 4 months) in the opistobranch mollusk Cadlina laevis were studied. Heterochronies manifested in positive allometry of the sensory organs, ganglia of the central nervous system, and the pharyngeal region of the digestive system in relation to general body sizes in juvenile individuals compared to adult animals were detected.

Menin: a tumor suppressor that mediates postsynaptic receptor expression and synaptogenesis between central neurons of Lymnaea stagnalis

Neurotrophic factors (NTFs) support neuronal survival, differentiation, and even synaptic plasticity both during development and throughout the life of an organism. However, their precise roles in central synapse formation remain unknown. Previously, we demonstrated that excitatory synapse formation in Lymnaea stagnalis requires a source of extrinsic NTFs and receptor tyrosine kinase (RTK) activation. Here we show that NTFs such as Lymnaea epidermal growth factor (L-EGF) act through RTKs to trigger a specific subset of intracellular signalling events in the postsynaptic neuron, which lead to the activation of the tumor suppressor menin, encoded by Lymnaea MEN1 (L-MEN1) and the expression of excitatory nicotinic acetylcholine receptors (nAChRs). We provide direct evidence that the activation of the MAPK/ERK cascade is required for the expression of nAChRs, and subsequent synapse formation between pairs of neurons in vitro. Furthermore, we show that L-menin activation is sufficient for the expression of postsynaptic excitatory nAChRs and subsequent synapse formation in media devoid of NTFs. By extending our findings in situ, we reveal the necessity of EGFRs in mediating synapse formation between a single transplanted neuron and its intact presynaptic partner. Moreover, deficits in excitatory synapse formation following EGFR knock-down can be rescued by injecting synthetic L-MEN1 mRNA in the intact central nervous system. Taken together, this study provides the first direct evidence that NTFs functioning via RTKs activate the MEN1 gene, which appears sufficient to regulate synapse formation between central neurons. Our study also offers a novel developmental role for menin beyond tumour suppression in adult humans.

Na+-K+-ATPase trafficking induced by heat shock pretreatment correlates with increased resistance to anoxia in locusts

The sensitivity of insect nervous systems to anoxia can be modulated genetically and pharmacologically, but the cellular mechanisms responsible are poorly understood. We examined the effect of a heat shock pretreatment (HS) on the sensitivity of the locust (Locusta migratoria) nervous system to anoxia induced by water immersion. Prior HS made locusts more resistant to anoxia by increasing the time taken to enter a coma and by reducing the time taken to recover the ability to stand. Anoxic comas were accompanied by surges of extracellular potassium ions in the neuropile of the metathoracic ganglion, and HS reduced the time taken for clearance of excess extracellular potassium ions. This could not be attributed to a decrease in the activity of protein kinase G, which was increased by HS. In homogenates of the metathoracic ganglion, HS had only a mild effect on the activity of Na(+)-K(+)-ATPase. However, we demonstrated that HS caused a threefold increase in the immunofluorescent localization of the α-subunit of Na(+)-K(+)-ATPase in metathoracic neuronal plasma membranes relative to background labeling of the nucleus. We conclude that HS induced trafficking of Na(+)-K(+)-ATPase into neuronal plasma membranes and suggest that this was at least partially responsible for the increased resistance to anoxia and the increased rate of recovery of neural function after a disturbance of K(+) homeostasis.

Transcriptome of the female synganglion of the black-legged tick Ixodes scapularis (Acari: Ixodidae) with comparison between Illumina and 454 systems

Illumina and 454 pyrosequencing were used to characterize genes from the synganglion of female Ixodes scapularis. GO term searching success for biological processes was similar for samples sequenced by both methods. However, for molecular processes, it was more successful for the Illumina samples than for 454 samples. Functional assignments of transcripts predicting neuropeptides, neuropeptide receptors, neurotransmitter receptors and other genes of interest was done, supported by strong e-values (<-6), and high consensus sequence alignments. Transcripts predicting 15 putative neuropeptide prepropeptides ((allatostatin, allatotropin, bursicon α, corticotropin releasing factor (CRF), CRF-binding protein, eclosion hormone, FMRFamide, glycoprotein A, insulin-like peptide, ion transport peptide, myoinhibitory peptide, inotocin ( =  neurophysin-oxytocin), Neuropeptide F, sulfakinin and SIFamide)) and transcripts predicting receptors for 14 neuropeptides (allatostatin, calcitonin, cardioacceleratory peptide, corazonin, CRF, eclosion hormone, gonadotropin-releasing hormone/AKH-like, insulin-like peptide, neuropeptide F, proctolin, pyrokinin, SIFamide, sulfakinin and tachykinin) are reported. Similar to Dermacentor variabilis, we found transcripts matching pro-protein convertase, essential for converting neuropeptide hormones to their mature form. Additionally, transcripts predicting 6 neurotransmitter/neuromodulator receptors (acetylcholine, GABA, dopamine, glutamate, octopamine and serotonin) and 3 neurotransmitter transporters (GABA transporter, noradrenalin-norepinephrine transporter and Na+-neurotransmitter/symporter) are described. Further, we found transcripts predicting genes for pheromone odorant receptor, gustatory receptor, novel GPCR messages, ecdysone nuclear receptor, JH esterase binding protein, steroidogenic activating protein, chitin synthase, chitinase, and other genes of interest. Also found were transcripts predicting genes for spermatogenesis-associated protein, major sperm protein, spermidine oxidase and spermidine synthase, genes not normally expressed in the female CNS of other invertebrates. The diversity of messages predicting important genes identified in this study offers a valuable resource useful for understanding how the tick synganglion regulates important physiological functions.

Identification and expression of capa gene in the fire ant, Solenopsis invicta

Recent genome analyses suggested the absence of a number of neuropeptide genes in ants. One of the apparently missing genes was the capa gene. Capa gene expression in insects is typically associated with the neuroendocrine system of abdominal ganglia; mature CAPA peptides are known to regulate diuresis and visceral muscle contraction. The apparent absence of the capa gene raised questions about possible compensation of these functions. In this study, we re-examined this controversial issue and searched for a potentially unrecognized capa gene in the fire ant, Solenopsis invicta. We employed a combination of data mining and a traditional PCR-based strategy using degenerate primers designed from conserved amino acid sequences of insect capa genes. Our findings demonstrate that ants possess and express a capa gene. As shown by MALDI-TOF mass spectrometry, processed products of the S. invicta capa gene include three CAPA periviscerokinins and low amounts of a pyrokinin which does not have the C-terminal WFGPRLa motif typical of CAPA pyrokinins in other insects. The capa gene was found with two alternative transcripts in the CNS. Within the ventral nerve cord, two capa neurons were immunostained in abdominal neuromeres 2–5, respectively, and projected into ventrally located abdominal perisympathetic organs (PSOs), which are the major hormone release sites of abdominal ganglia. The ventral location of these PSOs is a characteristic feature and was also found in another ant, Atta sexdens.

Pharmacological blockade of gap junctions induces repetitive surging of extracellular potassium within the locust CNS

The maintenance of cellular ion homeostasis is crucial for optimal neural function and thus it is of great importance to understand its regulation. Glial cells are extensively coupled by gap junctions forming a network that is suggested to serve as a spatial buffer for potassium (K(+)) ions. We have investigated the role of glial spatial buffering in the regulation of extracellular K(+) concentration ([K(+)]o) within the locust metathoracic ganglion by pharmacologically inhibiting gap junctions. Using K(+)-sensitive microelectrodes, we measured [K(+)]o near the ventilatory neuropile while simultaneously recording the ventilatory rhythm as a model of neural circuit function. We found that blockade of gap junctions with either carbenoxolone (CBX), 18β-glycyrrhetinic acid (18β-GA) or meclofenamic acid (MFA) reliably induced repetitive [K(+)]o surges and caused a progressive impairment in the ability to maintain baseline [K(+)]o levels throughout the treatment period. We also show that a low dose of CBX that did not induce surging activity increased the vulnerability of locust neural tissue to spreading depression (SD) induced by Na(+)/K(+)-ATPase inhibition with ouabain. CBX pre-treatment increased the number of SD events induced by ouabain and hindered the recovery of [K(+)]o back to baseline levels between events. Our results suggest that glial spatial buffering through gap junctions plays an essential role in the regulation of [K(+)]o under normal conditions and also contributes to a component of [K(+)]o clearance following physiologically elevated levels of [K(+)]o.

The expression pattern of the genes engrailed, pax6, otd and six3 with special respect to head and eye development in Euperipatoides kanangrensis Reid 1996 (Onychophora: Peripatopsidae)

The genes otd/otx, six3, pax6 and engrailed are involved in eye patterning in many animals. Here, we describe the expression pattern of the homologs to otd/otx, six3, pax6 and engrailed in the developing Euperipatoides kanangrensis embryos. Special reference is given to the expression in the protocerebral/ocular region. E. kanangrensis otd is expressed in the posterior part of the protocerebral/ocular segment before, during and after eye invagination. E. kanangrensis otd is also expressed segmentally in the developing ventral nerve cord. The E. kanangrensis six3 is located at the extreme anterior part of the protocerebral/ocular segment and not at the location of the developing eyes. Pax6 is expressed in a broad zone at the posterior part of the protocerebral/ocular segment but only weak expression can be seen at the early onset of eye invagination. In late stages of development, the expression in the eye is upregulated. Pax6 is also expressed in the invaginating hypocerebral organs, thus supporting earlier suggestions that the hypocerebral organs in onychophorans are glands. Pax6 transcripts are also present in the developing ventral nerve cord. The segment polarity gene engrailed is expressed at the dorsal side of the developing eye including only a subset of the cells of the invaginating eye vesicle. We show that engrailed is not expressed in the neuroectoderm of the protocerebral/ocular segment as in the other segments. In addition, we discuss other aspect of otd, six3 and pax6 expression that are relevant to our understanding of evolutionary changes in morphology and function in arthropods.

Kinesin-1 acts with netrin and DCC to maintain sensory neuron position in Caenorhabditis elegans

The organization of neurons and the maintenance of that arrangement are critical to brain function. Failure of these processes in humans can lead to severe birth defects, mental retardation, and epilepsy. Several kinesins have been shown to play important roles in cell migration in vertebrate systems, but few upstream and downstream pathway members have been identified. Here, we utilize the genetic model organism Caenorhabditis elegans to elucidate the pathway by which the C. elegans Kinesin-1 Heavy Chain (KHC)/KIF5 ortholog UNC-116 functions to maintain neuronal cell body position in the PHB sensory neurons. We find that UNC-116/KHC acts in part with the cell and axon migration molecules UNC-6/Netrin and UNC-40/DCC in this process, but in parallel to SAX-3/Robo. We have also identified several potential adaptor, cargo, and regulatory proteins that may provide insight into the mechanism of UNC-116/KHC's function in this process. These include the cargo receptor UNC-33/CRMP2, the cargo adaptor protein UNC-76/FEZ and its regulator UNC-51/ULK, the cargo molecule UNC-69/SCOCO, and the actin regulators UNC-44/Ankyrin and UNC-34/Enabled. These genes also act in cell migration and axon outgrowth; however, many proteins that function in these processes do not affect PHB position. Our findings suggest an active posterior cell migration mediated by UNC-116/KHC occurs throughout development to maintain proper PHB cell body position and define a new pathway that mediates maintenance of neuronal cell body position.

The nociceptin/orphanin FQ-like opioid peptide in nervous periesophageal ganglia of land snail Helix aspersa

The neuropeptide nociceptin/orphanin FQ (N/OFQ) and its receptor are members of the endogenous opioid peptide family. In mammals N/OFQ modulates a variety of biological functions such as nociception, food intake, endocrine, control of neurotransmitter release, among others. In the molluscs Cepea nemoralis and Helix aspersa the administration of N/OFQ produces a thermopronociceptive effect. However, little is known about its existence and anatomic distribution in invertebrates. The aim of this study was to provide a detailed anatomical distribution of N/OFQ like peptide immunoreactivity (N/OFQ-IL), to quantify the tissue content of this peptide, as well as to demostrate molecular evidence of N/OFQ mRNA in the nervous tissue of periesophageal ganglia of the land snail H. aspersa. Immunohistochemical, immunocytochemical, radioimmunoanalysis (RIA) and reverse transcription-polymerase chain reaction (RT-PCR) techniques were used. With regard to RT-PCR, the primers to detect expression of mRNA transcripts from H. aspersa were derived from the rat N/OFQ opioid peptide. We show a wide distribution of N/OFQ-IL in neurons and fibers in all perioesophageal ganglia, fibers of the neuropile, nerves, periganglionar connective tissue, aortic wall and neurohemal sinuses. The total amount of N/OFQ-IL in the perioesophageal ganglia (7.75 ± 1.75 pmol/g of tissue) quantified by RIA was similar to that found in mouse hypothalamus (10.1 ± 1.6 pmol/g of tissue). In this study, we present molecular evidence of N/OFQ mRNA expression. Some N/OFQ-IL neurons have been identified as neuroendocrine or involved in olfaction, hydro-electrolyte regulation, feeding, and thermonociception. Therefore, we suggest that N/OFQ may participate in these snail functions.

Neuropeptidomics of the Australian sheep blowfly Lucilia cuprina (Wiedemann) and related Diptera

Insect neuropeptides are the most diverse and important group of messenger molecules that regulate almost all physiological processes, including behavior. In this study, we performed a combination of matrix assisted laser desorption ionization time of flight (MALDI-TOF) and electrospray ionization quadrupole time of flight (ESI-Q-TOF) mass spectrometry to analyze the peptidome of the brain and the neurohemal organs of the Australian sheep blowfly Lucilia cuprina and compared the data with those of related flies such as the gray flesh fly Sarcophaga (=Neobellieria) bullata; the cabbage root fly Delia radicum, the fruit fly Drosophila melanogaster, and the yellow fever mosquito, Aedes aegypti. Without counting low intensity signals of truncated peptides, 45 neuropeptides arising from 12 neuropeptide genes (adipokinetic hormone, CAPA-peptides, corazonin, extended FMRFamides, SIFamide, insect kinin, short neuropeptide F, NPLP-1 peptides, HUGIN-pyrokinin, sulfakinins, allatostatins A, putative eclosion hormone precursor peptide) were identified; sequences of extended FMRFamides were reported in a separate publication. The remarkable similarity of the peptidome of cyclorraphan flies, which contain a large number of ecologically important species, does not support the development of a species-specific neuropeptide-based insect pest control strategy. However, mass spectrometric approaches as shown here do not cover the entire peptidome or differences at the receptor level and it is possible that group-specific peptide ligands or receptors exist that escaped the detection.

CAPA-gene products in the haematophagous sandfly Phlebotomus papatasi (Scopoli)--vector for leishmaniasis disease

Sandflies (Phlebotominae, Nematocera, Diptera) are responsible for transmission of leishmaniasis and other protozoan-borne diseases in humans, and these insects depend on the regulation of water balance to cope with the sudden and enormous intake of blood over a very short time period. The sandfly inventory of neuropeptides, including those that regulate diuretic processes, is completely unknown. Direct MALDI-TOF/TOF mass spectrometric analysis of dissected ganglia of Phlebotomus papatasi, combined with a data-mining of sandfly genome 'contigs', was used to identify native CAPA-peptides, a peptide class associated with the regulation of diuresis in other hematophagous insects. The CAPA-peptides identified in this study include two CAPA-PVKs, differentially processed CAPA-PK, and an additional CAPA precursor peptide. The mass spectrometric analysis of different parts of the neuroendocrine system of the sandfly indicate that it represents the first insect which accumulates CAPA-PVKs exclusively in hormone release sites of abdominal ganglia and CAPA-PK (nearly) exclusively in the corpora cardiaca. Additionally, sandflies feature the smallest abdominal ganglia (~35 μm) where CAPA-peptides could be detected so far. The small size of the abdominal ganglia does not appear to affect the development of the median neurosecretory system as it obviously does in another comparably small insect species, Nasonia vitripennis, in which no capa-gene expression was found. Rather, immunocytochemical analyses confirm that the general architecture in sandflies appears identical to that of much larger mosquitoes.

Validation of internal reference genes for real-time quantitative polymerase chain reaction studies in the tick, Ixodes scapularis (Acari: Ixodidae)

Obtaining reliable gene expression data using real-time quantitative polymerase chain reaction (qPCR) is highly dependent on the choice of normalization method. We tested the expression stability of multiple candidate genes in the salivary glands (SG) and synganglia (SYN) of female Ixodes scapularis (Say) ticks in multiple blood-feeding phases. We found that the amount of total RNA in both the SG and SYN increases dramatically during tick feeding, with 34x and 5.8x increases from 62 and 7.1 ng of unfed tick, respectively. We tested candidate genes that were predicted from I. scapularis genome data to encode glyceraldehyde 3-phosphate dehydrogenase (gapdh), ribosomal protein L13A (l13a), TATA box-binding protein (tbp), ribosomal protein S4 (rps4), glucose 6-phosphate dehydrogenase (gpdh), and beta-glucuronidase (gusb). The geNorm and NormFinder algorithms were used to analyze data from different feeding phases (i.e., daily samples from unfed to fully engorged females over a 7-d period in three replicate experiments). We found that the rps4 and l13a genes showed highly stable expression patterns over the feeding duration in both the SG and SYN. Furthermore, the highly expressed rps4 gene makes it useful as a normalization factor when we perform studies using minute amounts of dissected tissue for qPCR. We conclude that rps4 and l13a, whether individually or as a pair, serve as suitable internal reference genes for qRT-PCR studies in the SG and SYN of I. scapularis.

Failure of long-term memory formation in juvenile snails is determined by acetylation status of histone H3 and can be improved by NaB treatment

Background

Animals’ capacities for different forms of learning do not mature simultaneously during ontogenesis but the molecular mechanisms behind the delayed development of specific types of memory are not fully understood. Mollusks are considered to be among the best models to study memory formation at the molecular level. Chromatin remodeling in developmental processes, as well as in long-term memory formation, was recently shown to play a major role. Histone acetylation is a key process in the chromatin remodeling and is regulated through the signaling cascades, for example MAPK/ERK. Previously, we found that MAPK/ERK is a key pathway in the formation of the food aversion reflex in Helix. Pretreatment with upstream ERK kinase inhibitor PD98059 prevented food avoidance learning in adult Helix. In contrast to adult snails, juveniles possess immature plasticity mechanisms of the avoidance reflex until the age of 2–3 months while the MAPK/ERK cascade is not activated after aversive learning. In the present study, we focused on the potential MAPK/ERK target - histone H3.

Methodology/Principal Findings

Here we found that a significant increase in histone H3 acetylation occurs in adult animals after learning, whereas no corresponding increase was observed in juveniles. The acetylation of histone H3 is regulated by ERK kinase, since the upstream ERK kinase inhibitor PD98059 prevented the increase of histone H3 acetylation upon learning. We found that the injection of histone deacetylase inhibitor sodium butyrate (NaB) prior to training led to induction in histone H3 acetylation and significantly ameliorated long-term memory formation in juvenile snails.

Conclusions/Significance

Thus, MAPK/ERK-dependent histone H3 acetylation plays an essential role in the formation of food aversion in Helix. Dysfunction of the MAPK/ERK dependent histone H3 acetylation might determine the deficiency of avoidance behavior and long-term plasticity in juvenile animals. Stimulation of histone H3 acetylation in juvenile animals by NaB promoted avoidance plasticity.

Septin 4, the drosophila ortholog of human CDCrel-1, accumulates in parkin mutant brains and is functionally related to the Nedd4 E3 ubiquitin ligase

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Although most PD cases are sporadic, several loci have been involved in the disease. parkin (PARK) is causative of autosomal recessive juvenile Parkinsonism (ARJP) and encodes an E3 ubiquitin ligase associated with proteasomal degradation. It was proposed that loss of PARK function may lead to the toxic accumulation of its substrates in the brain, thus causing dopaminergic (DA) neuron death. Indeed, the first identified PARK substrate was CDCrel-1, a protein of the Septin family that accumulates in ARPJ brains. Drosophila has been used as a successful model organism to study PD broadly contributing to the understanding of the disease. Consistently, park mutant flies recapitulate some key features of ARJP patients. In this scenario, we previously reported that overexpression of Septin 4 (Sep4), the Drosophila ortholog of CDCrel-1, is toxic for DA neurons and interacts physically with Park, thus suggesting that Sep4 could be a Park substrate in Drosophila. Confirming this hypothesis, we show that Sep4 accumulates in park mutant brains as its human counterpart. Furthermore, we demonstrate that Nedd4, another E3 ubiquitin ligase that may have a role in PD, is functionally related to Sep4 and could be involved in regulating Sep4 subcellular localization/trafficking.

Allatotropin, leucokinin and AKH in honey bees and other Hymenoptera

In the honey bee no allatotropin gene has been found, even though allatotropin stimulates the synthesis of juvenile hormone in this species. We report here that honey bees and other Hymenoptera do have a typical allatotropin gene, although the peptides predicted have a somewhat different structure from that of other insect allatotropins. Polyclonal antisera to honey bee allatotropin reacted with material in the neurohemal organs of the segmental nerves of abdominal ganglia. We were unable to find the allatotropin peptide using mass spectrometry in extracts from these tissues. Thus the expression of this gene in honey bees is less important than in other insect species. We also characterized the leucokinin gene which similarly appears to be very weakly expressed in worker honey bees. Unlike the allatotropin gene, which is conserved within Hymenoptera, the leucokinin gene is much more variable in structure and was not found in ants nor the parasitic wasp Nasonia vitripennis. The absence of significant expression of adipokinetic hormone (AKH) in the honey bee may be due to the existence of a second TATA box in the promotor region of the gene, which explains the production of an mRNA encoding a putative peptide precursor from which no AKH should be released. Such a second TATA box was not found in other Hymenoptera, and may therefore be specific for the two Apis species. It is suggested that functional disintegration of this important metabolic gene became possible in Apis because of the highly evolved social nature of the species.

Sublethal effect of copper toxicity against histopathological changes in the spiny lobster, Panulirus homarus (Linnaeus, 1758)

The tissue damage induced by various organic pollutants in aquatic animals is well documented, but there is a dearth of information relating to the histological alterations induced by copper in the spiny lobster. In the present study, intermoult juveniles of the spiny lobster Panulirus homarus (average weight 150-200 g) were exposed to two sublethal concentrations of the copper (9.55 and 19.1 μg/l) for a period of 28 days. The muscle, hepatopancreas, midgut, gills, thoracic ganglion and heart of the lobsters were then dissected out and processed for light microscopic studies. Exposure to copper was found to result in several alterations in the histoarchitecture of the muscle, hepatopancreas, midgut, gills, thoracic ganglion and heart of P. homarus. The alterations included disruption and congestion of muscle bundle in muscle tissue; blackened haemocytes; distended lumen and F cell; necrosis of the tubules of the hepatopancreas; disarrangement of circular muscle of the midgut; accumulation of haemocytes in the haemocoelic space; swelling and fusion of lamellae; abnormal gill tips; hyperplastic, necrotic, and blackened secondary gill lamellae of the gills; damaged neurosecretory cell and sensory and motor fibre; necrotic of the thoracic ganglion; dispersedly arranged muscle bands; clumped satellite cells and nucleus of the heart. The results obtained suggest that the muscle, hepatopancreas, midgut, gills, thoracic ganglion and heart of lobsters exposed to copper were structurally altered. Such alterations could affect vital physiological functions, such as absorption, storage and secretion of the hepatopancreas, digestion of gut and respiration, osmotic and ionic regulations of the gills, which in turn could ultimately affect the survival and growth of P. homarus. Thus, all possible remedial measures should be adopted to prevent the occurrence of copper contamination in the aquatic environment.

Unique ionotropic receptors for D-aspartate are a target for serotonin-induced synaptic plasticity in Aplysia californica

The non-L-glutamate (L-Glu) receptor component of D-aspartate (D-Asp) currents in Aplysia californica buccal S cluster (BSC) neurons was studied with whole cell voltage clamp to differentiate it from receptors activated by other well-known agonists of the Aplysia nervous system and investigate modulatory mechanisms of D-Asp currents associated with synaptic plasticity. Acetylcholine (ACh) and serotonin (5-HT) activated whole cell excitatory currents with similar current voltage relationships to D-Asp. These currents, however, were pharmacologically distinct from D-Asp. ACh currents were blocked by hexamethonium (C6) and tubocurarine (D-TC), while D-Asp currents were unaffected. 5-HT currents were blocked by granisetron and methysergide (MES), while D-Asp currents were unaffected. Conversely, while (2S,3R)-1-(Phenanthren-2-carbonyl)piperazine-2,3-dicarboxylic acid(PPDA) blocked D-Asp currents, it had no effect on ACh or 5-HT currents. Comparison of the charge area described by currents induced by ACh or 5-HT separately from, or with, D-Asp suggests activation of distinct receptors by all 3 agonists. Charge area comparisons with L-Glu, however, suggested some overlap between L-Glu and D-Asp receptors. Ten minute exposure to 5-HT induced facilitation of D-Asp-evoked responses in BSC neurons. This effect was mimicked by phorbol ester, suggesting that protein kinase C (PKC) was involved.

Protein expression following heat shock in the nervous system of Locusta migratoria

There is a thermal range for the operation of neural circuits beyond which nervous system function is compromised. Locusta migratoria is native to the semiarid regions of the world and provides an excellent model for studying neural phenomena. In this organism previous exposure to sublethal high temperatures (heat shock, HS) can protect neuronal function against future hyperthermia but, unlike many organisms, the profound physiological adaptations are not accompanied by a robust increase of Hsp70 transcript or protein in the nervous system. We compared Hsp70 increase following HS in the tissues of isolated and gregarious locusts to investigate the effect of population density. We also localized Hsp70 in the metathoracic ganglion (MTG) of gregarious locusts to determine if HS affects Hsp70 in specific cell types that could be masked in whole ganglion assays. Our study indicated no evidence of a consistent change in Hsp70 level in the MTG of isolated locusts following HS. Also, Hsp70 was mainly localized in perineurium, neural membranes and glia and prior HS had no effect on its density or distribution. Finally, we applied 2-D gels to study the proteomic profile of MTG in gregarious locusts following HS; although these experiments showed some changes in the level of ATP-synthase β isoforms, the overall amount of this protein was found unchanged following HS. We conclude that the constitutive level of Hsps in the tissues of locusts is high. Also the thermoprotective effect of HS on the nervous system might be mediated by post-translational modifications or protein trafficking.

Bursicon-expressing neurons undergo apoptosis after adult ecdysis in the mosquito Anopheles gambiae

Neuropeptides are important regulators of diverse processes during development. The insect neuropeptide bursicon, a 30 kDa heterodimer, controls the hardening of the new cuticle after the shedding of the old one (ecdysis) and the inflation and maturation of adult wings. Given this specific functional role, its expression should only be required transiently because adult insects no longer undergo ecdysis. Here we report the transient expression of bursicon in the mosquito, Anopheles gambiae. Quantitative RT-PCR revealed that transcription of the bursicon monomers, burs and pburs, steadily increases through the larval stages, peaks in the black pupa stage, and decreases to below detectable levels by 8 h after adult ecdysis (eclosion). Immunohistochemistry on the adult nervous system showed that bursicon is co-expressed with crustacean cardioactive peptide (CCAP) in specific neurons of the abdominal ganglia, but that labeling intensity wanes by 14 h post-eclosion. Finally, detection of disintegrating DNA by TUNEL labeling demonstrated that the bursicon expressing neurons successively undergo apoptosis following eclosion. Taken altogether, these data describe A. gambiae as another holometabolous insect in which bursicon ceases to be produced in adults, and in which the bursicon expressing neurons are removed from the ventral nerve cord.

Multiple changes in peptide and lipid expression associated with regeneration in the nervous system of the medicinal leech

BACKGROUND

The adult medicinal leech central nervous system (CNS) is capable of regenerating specific synaptic circuitry after a mechanical lesion, displaying evidence of anatomical repair within a few days and functional recovery within a few weeks. In the present work, spatiotemporal changes in molecular distributions during this phenomenon are explored. Moreover, the hypothesis that neural regeneration involves some molecular factors initially employed during embryonic neural development is tested.

RESULTS

Imaging mass spectrometry coupled to peptidomic and lipidomic methodologies allowed the selection of molecules whose spatiotemporal pattern of expression was of potential interest. The identification of peptides was aided by comparing MS/MS spectra obtained for the peptidome extracted from embryonic and adult tissues to leech transcriptome and genome databases. Through the parallel use of a classical lipidomic approach and secondary ion mass spectrometry, specific lipids, including cannabinoids, gangliosides and several other types, were detected in adult ganglia following mechanical damage to connected nerves. These observations motivated a search for possible effects of cannabinoids on neurite outgrowth. Exposing nervous tissues to Transient Receptor Potential Vanilloid (TRPV) receptor agonists resulted in enhanced neurite outgrowth from a cut nerve, while exposure to antagonists blocked such outgrowth.

CONCLUSION

The experiments on the regenerating adult leech CNS reported here provide direct evidence of increased titers of proteins that are thought to play important roles in early stages of neural development. Our data further suggest that endocannabinoids also play key roles in CNS regeneration, mediated through the activation of leech TRPVs, as a thorough search of leech genome databases failed to reveal any leech orthologs of the mammalian cannabinoid receptors but revealed putative TRPVs. In sum, our observations identify a number of lipids and proteins that may contribute to different aspects of the complex phenomenon of leech nerve regeneration, establishing an important base for future functional assays.

Genetic feminization of the thoracic nervous system disrupts courtship song in male Drosophila melanogaster

Despite the growing research investigating the sex-specific organization of courtship behavior in Drosophila melanogaster, much remains to be understood about the sex-specific organization of the motor circuit that drives this behavior. To investigate the sex-specification of a tightly patterned component of courtship behavior, courtship song, the authors used the GAL4/UAS targeted gene expression system to feminize the ventral ganglia in male Drosophila and analyzed the acoustic properties of courtship song. More specifically, the authors used the thoracic-specifying teashirt promoter (tsh(GAL4)) to express feminizing transgenes specifically in the ventral ganglia. When tsh(GAL4) drove expression of transformer (tra), males were unable to produce prolonged wing extensions. Transgenic expression of an RNAi construct directed against male-specific fruitless (fru(M)) transcripts resulted in normal wing extension, but highly defective courtship song, with 58% of males failing to generate detectable courtship song. Of those that did sing, widths of individual pulses were significantly broader than controls, suggesting thoracic fru(M) function serves to mediate proprioceptive-dependent wing vibration damping during pulse song. However, the most critical signal in the song, the interpulse interval, remained intact. The inability to phenocopy this effect by reducing fru(M) expression in motor neurons and proprioceptive neurons suggests thoracic interneurons require fru(M) for proper pulse song execution and patterning of pulse structure, but not for pulse timing. This provides evidence that genes establishing sex-specific activation of complex behaviors may also be used in establishing pattern-generating motor networks underlying these sex-specific behaviors.

Dopamine enhances locomotor activity for mating in male honeybees (Apis mellifera L.)

Dopamine plays multiple roles in the regulation of reproduction in female honeybees where it appears to act independently of juvenile hormone (JH). In males the role of dopamine and its relationship to JH control have not been elucidated. In the present study we determined hemolymph levels of dopamine and its metabolite (N-acetyldopamine) in males at post-emergence days 0-16. The development of locomotor and flight activities were recorded over the same period. Hemolymph levels of dopamine and N-acetyldopamine were found to increase at the time of onset of mating flight activity and those of dopamine decreased thereafter. Both locomotor and flight activities increased in parallel with hemolymph dopamine levels but the increased activity levels were maintained following decline of dopamine levels. Brain and meso-metathoracic ganglia levels of dopamine showed a similar developmental profile to hemolymph dopamine levels. Locomotor activities were temporarily inhibited by injection of a dopamine-receptor antagonist (cis(Z)-flupenthixol) into the thorax, and were enhanced by injection of a dopamine-receptor agonist (6,7-ADTN). These results suggest that dopamine regulates locomotor activities for mating and plays a role downstream of JH in premature males in honeybees.

Circadian oscillations outside the optic lobe in the cricket Gryllus bimaculatus

Although circadian rhythms are found in many peripheral tissues in insects, the control mechanism is still to be elucidated. To investigate the central and peripheral relationships in the circadian organization, circadian rhythms outside the optic lobes were examined in the cricket Gryllus bimaculatus by measuring mRNA levels of period (per) and timeless (tim) genes in the brain, terminal abdominal ganglion (TAG), anterior stomach, mid-gut, testis, and Malpighian tubules. Except for Malpighian tubules and testis, the tissues showed a daily rhythmic expression in either both per and tim or tim alone in LD. Under constant darkness, however, the tested tissues exhibited rhythmic expression of per and tim mRNAs, suggesting that they include a circadian oscillator. The amplitude and the levels of the mRNA rhythms varied among those rhythmic tissues. Removal of the optic lobe, the central clock tissue, differentially affected the rhythms: the anterior stomach lost the rhythm of both per and tim; in the mid-gut and TAG, tim expression became arrhythmic but per maintained rhythmic expression; a persistent rhythm with a shifted phase was observed for both per and tim mRNA rhythms in the brain. These data suggest that rhythms outside the optic lobe receive control from the optic lobe to different degrees, and that the oscillatory mechanism may be different from that of Drosophila.

[Metabotropic glutamate receptors in the mechanisms of plasticity of central nervous system of the honeybee Apis mellifera]

Localization of metabotropic glutamate receptors (MGR) in head ganglion of honeybee Apis mellifera, and mechanisms of participation of activated MGR in CNS plasticity are investigated by means of complex approach using immunochemical, electrophysiological and behavioral methods. Influense of MGR activation on GABAergic system and ionotropic glutamate receptors (IGR) of AMPA- and NMDA-subtypes in studied. MGRa are revealed in lateral and medial calices of mushroom bodies. The inhibiting influence of MGR on AMPA- and NMDA receptors is shown using method of conditioned reflex. Previous activation of MGR neutralizes the inhibiting effect of GABA. Modulating role of heterogeneous MGR population in mechanisms of CNS plasticity on the level of glutamate-ergic synapse, and at interaction with GABAergic system is discussed.

[Coordination between locomotor and respiratory rhythms in the great ramshorn snail Planorbarius corneus: transmitter-dependent modifications]

In a reduced preparation of Planorbarius corneus consisting of the CNS and mantle complex, both the dopamine precursor L-DOPA and the serotonin precursor 5-HTP have been found to be able to induce and maintain rhythmic pneumostome (PN) movements phase-coupled to fictive cyclic locomotion in a neurotransmitter-specific manner. After the transection of pedal commissures, pharmacologically induced PN movements were coordinated with the locomotor activity rhythm generated by the left pedal ganglion, as in Lymnaea regardless of spatial inversion of its CNS. Nevertheless, in Planorbarius during the 5-HTP-induced fictive muscular locomotion, the PN was never opened, but cuddled up to the mantle at the same phase of the locomotor cycle corresponding to close down the PN in Lymnaea.

Different actions of ecdysis-triggering hormone on the brain and ventral nerve cord of the hornworm, Manduca sexta

Ecdysis, or the shedding of the old cuticle, depends on coordinated stereotyped behaviors, regulated by a number of neuropeptides. In the hornworm, Manduca sexta, two neuropeptides interact, namely ecdysis-triggering hormone (ETH) and eclosion hormone. We looked at the effects of ETH in vivo and in vitro, on the brain and the ventral nerve cord to determine the roles played by these hormones. We monitored ecdysis onset and the presence of cGMP and eclosion hormone immunoreactivity. In vivo, only a fraction of larvae lacking the cell bodies containing eclosion hormone, and injected with ETH, were able to undergo ecdysis, with a delayed response. These animals showed strongest cGMP immunoreactivity in the subesophageal and thoracic ganglia, with concomitant reductions in eclosion hormone immunoreactivity in descending axons in comparison with animals not undergoing ecdysis. Animals lacking the brain showed reduced to no cGMP levels in all ganglia. In vitro, isolated CNS preparations lacking the brain initiated ecdysis motor programs after incubation in ETH, with faster onset times than controls, and with reduced cGMP immunoreactivity. If ETH was applied only to the brain of the isolated CNS, cGMP immunoreactivity was noted primarily in the subesophageal and thoracic ganglia, with a decrease in eclosion hormone immunoreactivity in descending axons. ETH addition to the rest of the nerve cord showed reduced eclosion hormone immunoreactivity but little to no cGMP immunoreactivity in any ganglion. Controls showed strong cGMP immunoreactivity in all ganglia, and even greater reductions in eclosion hormone staining after ETH application. These results support previous suggestions that eclosion hormone is required for a positive feedback loop with ETH as well as onset of an inhibitory component, but also suggest that ETH stimulates eclosion hormone release at multiple spike initiation zones. The resultant up regulation of cGMP does not appear to be required for onset of ecdysis. A new model for ecdysis regulation is considered.

Effect of melatonin in the antioxidant defense system in the locomotor muscles of the estuarine crab Neohelice granulata (Decapoda, Brachyura)

In vertebrates, many studies verified different effects of melatonin in the antioxidant defense system (ADS). In crustaceans, few studies have been conducted to verify this possibility. We verified the melatonin effects in the crab Neohelice granulata using low (0.002 and 0.02 pmol/crab) and high (2.0 and 20.0 pmol/crab) melatonin dosages in short-term (0.5h) and long-term (9.5h) experiments. We analyzed the antioxidant capacity against peroxyl radicals (ACAP), reactive oxygen species (ROS) concentration, levels of by products of lipid peroxidation (LPO), oxygen consumption (VO(2)), the activity of glutamate cysteine ligase (gamma-GCL) and catalase (CAT) and glutathione content (GSH). Finally, the effects of exogenous melatonin were verified in terms of melatonin and N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) content in the muscles of N. granulata. In short-term experiment and low dosages, melatonin increased the VO(2), gamma-GCL activity and GSH content (p<0.05) and decreased melatonin content (p<0.05) without effects in ROS, ACAP and LPO (p>0.05). Possibly, melatonin is acting in the ADS increasing its efficiency and/or acting in mitochondrial activity and/or through signaling muscles to increase its consumption. AFMK was only detected in the eyestalk and cerebroid ganglia. In high dosages melatonin effects decreased, possibly by the desensitization of their receptors. In long-term experiment, melatonin decreased ACAP (p<0.05), and CAT activity (p<0.05) in low dosages. In high dosages melatonin reduced VO(2) (p<0.05) and increased ACAP (p<0.05), possibly stimulating others components of the ADS. In conclusion, melatonin in the locomotor muscles of N. granulata affects the antioxidant/pro-oxidant balance in a time and dosage dependent manner.

Changes in the auditory neuropil after deafferentation in adult grasshoppers (Schistocerca gregaria)

Nervous systems are capable of structural adjustments. Such plastic changes also occur in the auditory system of the locust Schistocerca gregaria in which a deafferentation leads to compensatory mechanisms, such as collateral sprouting of interneurons. In this study we further investigated lesion related changes in the major auditory neuropil, the median ventral association center (mVAC) of the metathoracic ganglion. The auditory sensory organ of adult locusts was unilaterally extirpated and the mVAC was histologically and immunocytochemically analyzed until 20 days postoperative. Measurements of the neuropil area in transverse sections showed a decrease in size. The putative transmitter of the afferents, acetylcholine, was investigated by acetylcholinesterase histochemistry. Comparisons of staining intensities in the intact and deafferentated mVAC indicated that the amount of acetylcholinesterase in the deafferentated mVAC decreased shortly after the operation. Both, the decreases in size of the mVAC as well as that in acetylcholinesterase histochemistry were only less than 10% compared to the controls. The immunoreactivity against the neurotransmitters gamma-amino butyric acid and serotonin was not influenced by the deafferentation.

Localization of biogenic amines in the foregut of Aplysia californica: catecholaminergic and serotonergic innervation

This study examined the catecholaminergic and serotonergic innervation of the foregut of Aplysia californica, a model system in which the control of feeding behaviors can be investigated at the cellular level. Similar numbers (15-25) of serotonin-like-immunoreactive (5HTli) and tyrosine hydroxylase-like-immunoreactive (THli) fibers were present in each (bilateral) esophageal nerve (En), the major source of pregastric neural innervation in this system. The majority of En 5HTli and THli fibers originated from the anterior branch (En(2)), which innervates the pharynx and the anterior esophagus. Fewer fibers were present in the posterior branch (En(1)), which innervates the majority of the esophagus and the crop. Backfills of the two En branches toward the central nervous system (CNS) labeled a single, centrifugally projecting serotonergic fiber, originating from the metacerebral cell (MCC). The MCC fiber projected only to En(2). No central THli neurons were found to project to the En. Surveys of the pharynx and esophagus revealed major differences between their patterns of catecholaminergic (CA) and serotonergic innervation. Whereas THli fibers and cell bodies were distributed throughout the foregut, 5HTli fibers were present in restricted plexi, and no 5HTli somata were detected. Double-labeling experiments in the periphery revealed THli neurons projecting toward the buccal ganglion via En(2). Other afferents received dense perisomatic serotonergic innervation. Finally, qualitative and quantitative differences were observed between the buccal motor programs (BMPs) produced by stimulation of the two En branches. These observations increase our understanding of aminergic contributions to the pregastric regulation of Aplysia feeding behaviors.

Neuropeptides associated with the regulation of feeding in insects

The stomatogastric nervous system plays a pivotal role in feeding behaviour. Central to this system is the frontal ganglion, which is responsible for foregut motor activity, and hence the passage of food through the gut. Many insect peptides, which exhibit myoactivity on the visceral muscles of the gut in vitro, have been detected in the stomatogastric nervous system by immunochemical or mass spectrometric techniques. This localisation of myoactive peptides, particularly in the frontal ganglion, implies roles for these peptides in the neural control and modulation of feeding in insects. Insect sulfakinins, tachykinins, allatotropin and proctolin have all been shown to stimulate the foregut muscles, whereas myosuppressins, myoinhibitory peptides and allatostatins all inhibited spontaneous contractions of the foregut in a variety of insects. Some of these peptides, when injected, inhibited feeding in vivo. Both the A-type and B-type allatostatins suppressed feeding activity when injected into the cockroach, Blattella germanica and the Manduca sexta C-type allatostatin and allatotropin inhibited feeding when injected into the larvae of two noctuid moths, Lacanobia oleracea and Spodoptera frugiperda, respectively. Injection of sulfakinins into the fly Phormia regina, the locust Schistocera gregaria and the cockroach B. germanica also suppressed feeding, whereas silencing the sulfakinin gene through the injection of double stranded RNA resulted in an increase in food consumption in the cricket Gryllus bimaculatus. The regulation of feeding in insects is clearly very complex, and involves the interaction of a number of mechanisms, one of which is the release, either centrally or locally, of neuropeptides. However, the role of neuropeptides, their mechanisms of action, interactions with each other, and their release are still poorly understood. It is also unclear why insects possess such a number of different peptides, some with multiples copies or homologues, which stimulate or inhibit gut motility, and how their release, sometimes from the same neurone, is regulated. These neuropeptides may also act at sites other than visceral muscles, such as centrally through the brain or on gut stretch receptors.

Innexin genes and gap junction proteins in the locust frontal ganglion

Gap junctions (GJs) belong to one of the most conserved cellular structures in multicellular organisms. They probably serve similar functions in all Metazoa, providing one of the most common forms of intercellular communication. GJs are widely distributed in embryonic cells and tissues and have been attributed an important role in development, modulating cell growth and differentiation. These channels have been also implicated in mediating electrical synaptic signaling; Coupling through GJs is now accepted as a major pathway that supports network behavior and contributes to physiological rhythms. Here we focus on the physiology and molecular biology of GJs in a recently established model for the study of rhythm-generating networks and their role in behavior: the frontal ganglion (FG) of the desert locust, Schistocerca gregaria. Four novel genes of the invertebrate GJs (innexin) gene family were found to be expressed in the FG: Sg-inx1, Sg-inx2, Sg-inx3 and Sg-inx4. Immunohistochemistry revealed that some of the neurons in the FG express at least one innexin protein, INX1. We also established the presence of functional gap junction proteins in the FG and demonstrated functional electrical coupling between the neurons in the FG. This study forms the basis for further investigation of the role of GJs in network development and behavior.

Two peptide transmitters co-packaged in a single neurosecretory vesicle

Numerous neurosecretory cells are known to secrete more than one peptide, in both vertebrates and invertebrates. These co-expressed neuropeptides often originate from differential cleavage of a single large precursor, and are then usually sorted in the regulated pathway into different secretory vesicle classes to allow separable release dynamics. Here, we use immuno-gold electron microscopy to show that two very different neuropeptides (the nonapeptide crustacean cardioactive peptide (CCAP) and the 30 kDa heterodimeric bursicon) are co-packaged within the same dense core vesicles in neurosecretory neurons in the abdominal ganglia of Periplaneta americana. We suggest that this co-packaging serves a physiological function in which CCAP accelerates the distribution of bursicon to the epidermis after ecdysis to regulate sclerotization of the newly formed cuticle.

The neurotoxic effects of manganese on the dopaminergic innervation of the gill of the bivalve mollusc, Crassostrea virginica

We examined effects of manganese on the nervous system and innervation of lateral cilia of Crassostrea virginica. While essential in trace amounts, tissue manganese accumulation is neurotoxic, inducing Manganism, a Parkinson's-like disease in humans. Lateral cilia of the gill of C. virginica are controlled by a reciprocal serotonergic-dopaminergic innervation from their ganglia. Oysters were incubated 3 days in the presence of up to 1 mM manganese, followed by superfusion of the cerebral ganglia, visceral ganglia or gill with dopamine or serotonin. Beating rates of cilia were measured by stroboscopic microscopy of isolated gill preparations or gill preparations with the ipsilateral cerebral and/or visceral ganglia attached. Acute manganese treatments impaired the dopaminergic, cilio-inhibitory system, while having no effect on the serotonergic, cilio-excitatory system, which is in agreement with the proposed mechanism of manganese toxicity in humans. Manganese treatments also decreased endogenous dopamine levels in the cerebral and visceral ganglia, and gills, but not serotonin levels. We demonstrated that manganese disrupts the animal's dopaminergic system, and also that this preparation can be used to investigate mechanisms that underlie manganese neurotoxicity. It also may serve as a model in pharmacological studies of drugs to treat or prevent Manganism and other dopaminergic cell disorders.