Gliotactin, a novel transmembrane protein on peripheral glia, is required to form the blood-nerve barrier in Drosophila

Peripheral glia help ensure that motor and sensory axons are bathed in the appropriate ionic and biochemical environment. In Drosophila, peripheral glia help shield these axons against the high K+ concentration of the hemolymph, which would largely abolish their excitability. Here, we describe the molecular genetic analysis of gliotactin, a novel transmembrane protein that is transiently expressed on peripheral glia and that is required for the formation of the peripheral blood-nerve barrier. In gliotactin mutant embryos, the peripheral glia develop normally in many respects, except that ultrastructurally and physiologically they do not form a complete blood-nerve barrier. As a result, peripheral motor axons are exposed to the high K+ hemolymph, action potentials fail to propagate, and the embryos are nearly paralyzed.

Cytological analysis of the urn cell complex of Sipunculus nudus before and after serum-induced secretion

This study analyzes the cytology of the urn cell complex (UCC) of Sipunculus nudus, an invertebrate cell model for humorally regulated mucus secretion. An unstimulated UCC is composed of a vesicle cell and a ciliated cell joined together by desmosomes. Another cell population (third-type cells) is frequently associated with ciliated cells. Vesicle cells are thin, have few mitochondria or lipid droplets, and enclose a bubble-like cavity containing microfibrillar material. Ciliated cells contain several rows of cilia that are anchored by prominent rootlets and propel UCCs forward. Five to six concentric bundles of microfilaments are distributed along the outer convexity of ciliated cells and may have a role in the plasticity of the UCC. Many fibrillar deposits that lack a demonstrable limiting membrane are distributed around intracytoplasmic vacuoles facing the mouth-like opening of the UCC. These deposits are reactive to periodic acid-Schiff and resistant to diastase. After stimulation with serum, they appear to migrate through the ciliated cell's plasma membrane, contributing to the formation of a secretory tail. Discharge of secretory material is not observed in third-type cells, which instead contain lysosome-like granules and autophagic-like vacuoles and become displaced distalward by the emerging tail of the UCC. This study indicates that formation and elongation of the UCC secretory tail are functions of ciliated cells.

Stabilization of supercooled fluids by thermal hysteresis proteins

It has been reported that thermal hysteresis proteins found in many cold-hardy, freeze-avoiding arthropods stabilize their supercooled body fluids. We give evidence that fish antifreeze proteins, which also produce thermal hysteresis, bind to and reduce the efficiency of heterogenous nucleation sites, rather than binding to embryonic ice nuclei. We discuss both possible mechanisms for stabilization of supercooled body fluids and also describe a new method for measuring and defining the supercooling point of small volumes of liquid.

Cytokines and evolution: in vitro effects of IL-1 alpha, IL-1 beta, TNF-alpha and TNF-beta on an ancestral type of stress response

Invertebrate hemocytes are immune-neuroendocrine cells which contain a variety of cytokines [Ottaviani et al. (1993) Biochem. Biophys. Res. Commun. 195, 984-988] and release biogenic amines when added to corticotropin-releasing factor (CRF), a phenomenon we have described as an evolutionary proto-type stress response [Ottaviani et al. (1991) Proc. R. Soc. Lond. B 245, 215-218]. Here we show in two molluscs, Planorbarius corneus and Viviparus ater, that this response is significantly reduced when hemocytes are pre-incubated with IL-1 alpha, IL-1 beta, TNF-alpha and TNF-beta before the addition of CRF. These results confirm and extend the hypothesis that a deep evolutionary relationship exists between cytokines and stress response. Moreover, these data offer an evolutionary basis for understanding the promiscuity of cytokine receptors.

Cryobiology of the face fly and house fly (Diptera: Muscidae)

Face flies, Musca autumnalis De Geer, have a circumpolar distribution and overwinter as adults in reproductive diapause. House flies, Musca domestica L., have a cosmopolitan distribution and overwinter in northern latitudes in animal confinement quarters. We compared supercooling points with low temperature tolerances, as measured by bioassays, in all developmental stages of both species. There was no correlation between supercooling points and the ability to survive subzero temperatures. Rapid cold hardening was induced in adults of both species by a 2-h acclimation period at 0 degrees C. Hemolymph melting points were measured osmometrically in diapausing and reproductive face flies. Freezing point depressions differed between diapausing and reproductive flies and between reproductive flies given a 2-h pre-exposure to 0 degrees C and unexposed flies. Our data suggest that a -8 to 8 degrees C range with a mean close to 0 degrees C is necessary for successful face fly overwintering. House fly overwintering sites must offer microhabitats that remain above -5 degrees C with sufficient time above 10 degrees C to allow larval, pupal, and ovarian development.

Improved stability of Drosophila larval neuromuscular preparations in haemolymph-like physiological solutions

Neuromuscular preparations from third instar larvae of Drosophila are not well-maintained in commonly used physiological solutions: vacuoles form in the muscle fibers, and membrane potential declines. These problems may result from the Na:K ratio and total divalent cation content of these physiological solutions being quite different from those of haemolymph. Accordingly haemolymph-like solutions, based upon ion measurements of major cations, were developed and tested. Haemolymph-like solutions maintained the membrane potential at a relatively constant level, and prolonged the physiological life of the preparations. Synaptic transmission was well-maintained in haemolymph-like solutions, but the excitatory synaptic potentials had a slower time course and summated more effectively with repetitive stimulation, than in standard Drosophila solutions. Voltage-clamp experiments suggest that these effects are linked to more pronounced activation of muscle fiber membrane conductances in standard solutions, rather than to differences in passive muscle membrane properties or changes in postsynaptic receptor channel kinetics. Calcium dependence of transmitter release was steep in both standard and haemolymph-like solutions, but higher external calcium concentrations were required for a given level of release in haemolymph-like solutions. Thus, haemolymph-like solutions allow for prolonged, stable recording of synaptic transmission.

Differential blocking of coagulation-activating pathways of Limulus amebocyte lysate

The coagulation of Limulus amebocyte lysate (LAL) can be activated through two pathways, one initiated by endotoxin and the other by beta-glucans. The two pathways join at the step of activation of the proclotting enzyme. We report here that the endotoxin-activated pathway can be differentially inhibited by two methods in a Limulus enzyme-linked immunosorbent assay (ELISA), either by the combined use of dimethyl sulfoxide and polymyxin B or by a monoclonal antibody against Limulus factor C. LAL reactivities to 10 different endotoxin preparations could be inhibited by the former method by a factor of 10(4) to 10(6) and could be blocked almost totally by the latter method, irrespective of the source of endotoxin. The sensitivity of the assay was approximately 50 pg/ml both for curdlan from Alcaligenes faecalis and for laminarin from Laminaria digitata. We also found that the beta-glucan-activated pathway could be totally blocked by laminarin (> 1 microgram/ml) without affecting the endotoxin-activated pathway, allowing endotoxin to be quantitated specifically by the Limulus ELISA with a detection limit of 0.005 endotoxin unit per ml. The use of uninhibited and differentially inhibited ELISAs demonstrated that different LAL preparations showed much greater variation in assaying beta-glucans than in assaying endotoxins. The LAL reactivity of normal human plasma was found to be due to the activation of the beta-glucan pathway, but not the endotoxin pathway, of LAL.

Induction of cecropin-like and attacin-like antibacterial but not antiviral activity in Heliothis virescens larvae

Inducible cecropin-like and attacin-like proteins were isolated from immune hemolymph obtained from vaccinated Heliothis virescens larvae. The attacin-like protein had a molecular weight of approximately 25,000 daltons and was not dialyzable. The cecropin-like peptide had an estimated molecular weight of 6,000-7,000 daltons and was dialyzable, heat-stable and sensitive to trypsin digestion. The cecropin-like peptide showed bactericidal activity against Escherichia coli and Enterobacter cloacae, and the attacin-like protein showed bactericidal activity against E. coli. The immune hemolymph was bactericidal against E. coli, E. cloacae and Pseudomonas aeruginosa. Ultrastructural cell envelope damage to E. coli, produced by the immune hemolymph, was observed by scanning electron microscopy. No antiviral activity by the inducible cecropin-like and attacin-like proteins was detected against herpes simplex virus-1 and the vesicular stomatitis virus.

Interaction of mutants of Xenorhabdus nematophilus (Enterobacteriaceae) with antibacterial systems of Galleria mellonella larvae (Insecta: Pyralidae)

Xenorhabdus nematophilus mutants that took longer to kill insects than did the wild type were used to determine the relationship of the physicochemical properties and outer membrane composition to bacterial interaction with the antibacterial systems of Galleria mellonella larvae and to bacterial virulence. Insect serum slowed the growth of the wild-type and mutant bacteria. This was attributed to increased spheroplast formation for the mutants. Spheroplast formation was associated with an increased sensitivity to insect lysozyme and a reduction in overall bacterial cationic charge. Increasing bacterial hydrophobicity was correlated with both increased bacterial attachment to the insect's haemocytes and the accelerated removal of the bacteria from the haemolymph. Attachment of the mutants to the insect haemocytes also increased as the bacterial lipopolysaccharide content increased, the level of prophenoloxidase activation increased, and cationic charge declined. Bacterial emergence into the haemolymph occurred in parallel with haemocyte damage but neither the total lipopolysaccharide levels in the bacteria nor the rate of bacterial emergence were associated with virulence. The rate of lipopolysaccharide release into the haemolymph influenced the rate of haemocyte damage. The contribution of outer membrane proteins to lipopolysaccharide release, bacterial adhesion to haemocytes, and virulence is discussed. Virulence reflects bacterial tolerance to the host's antibacterial defences, favouring an increase in bacteria and toxic lipopolysaccharides.

Effects of physico-chemical treatments on haemagglutination activity of Anopheles gambiae haemolymph and midgut extract

Anopheles gambiae midgut extracts and haemolymph possessed agglutinins, titre 1:16 to 1:256, against human red blood cells (RBCs). Subjection of both tissues to protein precipitation reagents, organic chemical and selected protease, neuraminidase and other glycosidic hydrolase treatments revealed the haemagglutinins to be protein, most likely glycoprotein, in nature--not lipoprotein, lipid, glycolipid or nucleic acid. An.gambiae agglutinins were thermo-labile > 40 degrees C, affected by freezing and thawing treatments, and contained disulphide and hydrogen bonds on the basis of sensitivity following exposure to dithiothreitol and urea respectively. Optimum haemagglutination depended generally on slightly acid to neutral pH conditions and agglutinin activity was Ca2+ ion, albeit to a lesser extent Mg2+ ion, dependent. The midgut extract agglutinin subunit molecule had a relative molecular weight (M(r)) of 65 kDa whilst that of haemolymph was 40 kDa. This study presents the first report on selected physico-chemical properties, the glycoproteinaceous nature and tentative subunit M(r) of mosquito midgut extract and haemolymph anti-RBC agglutinin(s).

[Immunologic and parasitologic aspects of Biomphalaria tenagophila infected by Schistosoma mansoni and other Digenea]

The behavior of Biomphalaria tenagophila amoebocytes was studied in infections produced by Schistosoma mansoni and other Digenea. The resistance to superinfection was also verified in mixed infections. Data on amoebocyte phagocytic activity, on the number of amoebocytes in hemolymph, and on amoebocyte tissue reactions were obtained and electrophoretic and immunodiffusion examinations of the hemolymph were carried out. It was concluded that the snails infected with Digenea show resistance to superinfection with S. mansoni. Apparently sporocysts are not destroyed by the action of amoebocytes. An increase in amoebocyte phagocytic activity was discovered in infected snails. Immunoelectrophoresis shows quantitative and qualitative differences in the hemolymph of the infected snails.

Regulated tyrosine phosphorylation at the tips of growth cone filopodia

Several types of evidence suggest that protein-tyrosine phosphorylation is important during the growth of neuronal processes, but few specific roles, or subcellular localizations suggestive of such roles, have been defined. We report here a localization of tyrosine-phosphorylated protein at the tips of growth cone filopodia. Immunocytochemistry using a mAb to phosphorylated tyrosine residues revealed intense staining of the tips of most filopodia of Aplysia axons growing slowly on a polylysine substrate, but of few filopodia of axons growing rapidly on a substrate coated with Aplysia hemolymph, which has growth-promoting material. Cytochalasin D, which causes F-actin to withdraw rapidly from the growth cone, caused the tyrosine-phosphorylated protein to withdraw rapidly from filopodia, suggesting that the protein associates or interacts with actin filaments. Phosphotyrosine has previously been found concentrated at adherens junctions, where bundles of actin filaments terminate, but video-enhanced contrast-differential interference contrast and confocal interference reflection microscopy demonstrated that the filopodial tips were not adherent to the substrate. Acute application of either hemolymph or inhibitors of protein-tyrosine kinases to neurons on polylysine resulted in a rapid loss of intense staining at filopodial tips concomitant with a lengthening of the filopodia (and their core bundles of actin filaments). These results demonstrate that tyrosine-phosphorylated protein can be concentrated at the barbed ends of actin filaments in a context other than an adherens junction, indicate an association between changes in phosphorylation and filament dynamics, and provide evidence for tyrosine phosphorylation as a signaling mechanism in the filopodium that can respond to environmental cues controlling growth cone dynamics.

Antiviral melanization reaction of Heliothis virescens hemolymph against DNA and RNA viruses in vitro

1. Antiviral activity of Heliothis virescens larval hemolymph was determined using a cytotoxicity/virus inhibition test (TClD50) done in Vero cell tissue cultures. Excellent antiviral activity was found especially against herpes simplex viruses-1 and -2 and also against vesicular stomatitis, parainfluenza-3, coxsackie B3 and sindbis viruses. 2. Prolonged incubation of herpes simplex virus-1 and vesicular stomatitis virus with hemolymph was virucidal and greatly reduced infectivity of the two viruses in tissue culture. 3. Antiviral activity was produced by both normal and immune (vaccinated larvae) cell-free hemolymphs. 4. Antiviral activity against herpes simplex virus-1 could be generated in vitro with hemolymph phenoloxidase or mushroom tyrosinase using four different substrates including tyrosine. 5. Activation of the insect melanization reaction by phenoloxidase was necessary for antiviral activity to occur.

[The role of glucose in facilitating defensive reactions during feeding in the edible snail Helix lucorum]

The glucose role in a regulation of defense responses during feeding behaviour was studied in the snail Helix lucorum. It was found that 15-20 min after the beginning of the food intake the foot withdrawal response evoked by a train of electrical pulses was facilitated up to 20-30%. At the same time glucose concentration in the haemolymph increased from 0.5 +/- 0.1 mM in the starved molluscs to 0.9 +/- 0.5 mM in the snails at 20-25 min of eating. In the food satiated snails and 30-90 min after the food intake the glucose level in the haemolymph was 1.6 +/- 0.5 mM. It was shown that 0.5 ml glucose solution (5 mM) injected into the mantle cavity also facilitated the foot withdrawal defense response in the fastened snail, whereas injection of 2.5 mM or 10 mM glucose solutions were ineffective. These data support a supposition that glucose in one of the endogenous factors involved in regulation of defense behaviour during feeding in snails.

Octopamine effects mimick state-dependent changes in a proprioceptive feedback system

The modulatory actions of the biogenic amine octopamine on the femur tibia (FT) control loop in the stick insect Carausius morosus were examined. The response properties of the FT control loop were determined under open loop conditions. Mechanical stimulation of the femoral chordotonal organ (fCO) was the input and tibial movement and motoneuronal activity were measured as the output of the system. Following octopamine injection into the hemolymph of intact, inactive animals, two consecutive phases occurred at the behavioral level. Octopamine caused initially an activation of the animal. During this first phase (3.5-12 min duration) the response properties of the FT control loop were similar to those found in animals that were activated by tactile stimuli under normal conditions. Afterward, animals became inactive. During this second phase (15-20 min duration), the gain of the control loop was zero and no resistance reflex in the FT joint was generated in response to fCO stimulation. However, active movements of the tibia could still be elicited. As we could show in restrained animals, where DL-octopamine was applied topically onto the undesheated mesothoracic ganglion, the complete suppression of the resistance reflex on the motoneuronal level was dose dependent starting at concentrations of 5 x 10(-3) M octopamine. We could show that octopamine specifically suppressed the pathways involved in the resistance reflex, while feedback loop responses to fCO stimuli typical for active animals could still be elicited. Our results indicate that an increase in the octopamine concentration mimicks activation of the animal: Properties being characteristic for the control of the FT joint in the inactive animal are inhibited by octopamine, while properties of the FT control loop typical for the active animal appear to be facilitated following octopamine injection. The results clearly demonstrate that different pathways in the neuronal network underlying the FT control loop are involved in the responses of the control loop to fCO stimuli in the inactive and active behavioral states of the stick insect.

Luminol-dependent chemiluminescence of hemocytes derived from marine and estuarine molluscs

Hemocytes of two marine molluscs, Nerita albicilla (gastropod) and Mytilus edulis (bivalve), were stimulated in vitro with zymosan and live cells of Vibrio parahaemolyticus and Escherichia coli as determined by luminol-dependent chemiluminescence (CL). The CL response was enhanced in the presence of the respective molluscan plasma. Hemocytes of an estuarine gastropod, Clithon retropictus, showed low CL response to zymosan and V. parahaemolyticus, which was slightly enhanced in the presence of C. retropictus plasma. Hemocytes of an estuarine bivalve, Corbicula japonica, showed no CL response. CL response of hemocytes might be a useful tool to analyze defense mechanisms of estaurine molluscs.

Hormonal regulation and properties of a new group of basic hemolymph proteins expressed during insect metamorphosis

Two abundant basic proteins, and arylphorin, that are expressed during metamorphosis of Trichoplusia ni were isolated, their cDNAs cloned, and regulation of their expression assessed. According to the criteria of encoded protein sequence, positions of sequence coinitiation and cotermination, amino acid compositions, nonsex-specificity, and immunological analyses, the related yet distinct basic proteins do not correspond to any previously established group of insect proteins, each of which can be distinguished on the basis of such criteria, although they appear to be within the arthropod hemocyanin superfamily. The basic proteins can be separated under native isoelectric focusing conditions, indicating that they do not preferentially form heteromeric complexes under such conditions. While the transcripts for both basic proteins and a coexpressed acidic protein (Jones, G., Brown, N., Manczak, M., Hiremath, S., and Kafatos, F. (1990) J. Biol. Chem. 265, 8596-8602) appeared in both sexes on the day prior to ecdysteroid-driven metamorphic commitment, and persisted at high abundance for the next 24 h, the arylphorin mRNA appeared 1 day earlier and declined immediately after metamorphic commitment. The dynamics of suppression of the appearance and abundance of transcripts in response to maintenance of a high juvenile hormone titer was different for the acidic versus the two basic proteins. Another regulatory difference in response to juvenile hormone was shown by a decreased translatability of the mRNAs for the two basic proteins, but not for the acidic protein. In contrast, the abundance and translatability of arylphorin mRNA was insensitive to a high juvenile hormone level. A further difference in regulation was shown by the maintenance of a high level of both arylphorin and the acidic protein in the hemolymph after disappearance of their transcripts, while the basic proteins instead disappeared from the hemolymph and persisted in the fat body. These results establish at least three qualitatively different effects of juvenile hormone on the abundance of transcripts for these representatives of three groups in the hemocyanin superfamily, and also establish mRNA translatability as another differential level of regulation among them. Given these differences in mechanisms of regulation of evolutionarily related proteins, this system of metamorphosis-associated proteins in T. ni should prove to be a valuable tool in studies of mechanisms of hormonal regulation of gene expression during the metamorphic transformation of larval tissues.

Reevaluation of electrophoresis in the Drosophila egg chamber

To evaluate the hypothesis of electrophoretic transport of cytoplasmic components, the transfollicle potentials of Drosophila oocytes and nurse cells were measured using improved techniques. We found input resistances 20 to 1000 times higher than those in previous reports. Measurements were made in a large variety of conditions: in external potassium concentrations from 1 to 100 mM, over the concomitant membrane potential range -84 to -23 mV, from developmental stages 5 to 10, and with or without using hemolymph, anesthetics, or collagenase. In all of these circumstances, no voltage gradient was detectable with intracellular microelectrodes from nurse cells to oocyte or between nurse cells. No voltage gradient was detected with external suction electrodes. Our results do not support the electrophoretic theory.

Molecular mechanism of hemolymph clotting system in Limulus

Limulus (horseshoe crab) hemolymph is known to be very sensitive to bacterial endotoxin (LPS), which causes a rapid coagulation response. Hemolymph contains a single type of hemocyte that undergoes aggregation, adhesion, and degranulation in response to LPS. The granule contents are released into the hemolymph, where they form an insoluble gel. We have characterized four components involved in this coagulation response that comprise a cascade of three serine protease zymogens (factor C, factor B, and proclotting enzyme) and one clottable protein (coagulogen). Of these components, factor C sensitive to LPS is a protein composed of five complement-related domains ("Sushi" or SCR), an EGF-like domain, and a C-type lectinlike domain as well as a putative amino-terminal LPS-binding domain. This domain structure is very similar to that of selectin family of cell adhesion molecules, suggesting that it might also function as a cell adhesion molecule after the release into the hemolymph. Factor B and the proclotting enzyme share a common Cys-rich motif ("cliplike" domain) in the amino-terminal portions. This domain is also found in a putative serine protease zymogen ("easter") in Drosophila, which is essential for normal embryonic development. All four of the components of the cascade and an antibacterial protein (anti-LPS factor) are localized to a specific type of the hemocyte granule. Another antibacterial peptide (tachyplesins I and II) is localized in a distinct granule population. The contents of both granule populations are released into the hemolymph in response to LPS, where they cooperate in immobilization and killing of Gram-negative bacteria.

Growth properties of larval and adult locust neurons in primary cell culture

We developed a cell culture system for thoracic neurons of fifth instar or adult locusts (Locusta migratoria) in order to obtain maximum visualization of cellular morphology and direct access to the neurons for electrophysiological analysis. The dissociated neurons regenerated new neurites in a serum-free defined culture medium, in which they remained viable for up to 3 weeks. Viability of the cells was confirmed by intracellular recordings demonstrating active membrane properties and action potentials. While the morphology of the cultured neurons is distinct from their in vivo counterparts, they retained some cellular surface properties and markers related to transmitter metabolism. Two factors influencing cellular morphology in vitro were identified in Locusta: 1) the presence of a primary neurite stump, and 2) membrane contacts between cells. Dissociated neurons of the locust species Schistocerca gregaria grown in a hemolymph-enriched medium showed a marked reduction in branching patterns and a tenfold increase in neurite length compared to neurons growing in a medium without hemolymph. This culture system could prove useful for identifying the action of hemolymph-derived growth factors.

Regulation of methyl farnesoate in the hemolymph and mandibular organ of the lobster, Homarus americanus

Methyl farnesoate (MF) was measured in the hemolymph and mandibular organs (MO) of the lobster. Although a few animals had detectable MF levels in their hemolymph, this compound was undetectable (less than 0.4 ng/ml) in the hemolymph of most animals. One day after bilateral eyestalk ablation, MF was detected in the hemolymph of all animals, reaching variable levels (2.0-31.2 ng/ml) by the fourth day. Unilateral eyestalk ablation caused a smaller increase in hemolymph levels of MF. Similarly, the MF content of the MO, the only known site of MF synthesis, was low in intact lobsters (8.1 ng/gland) and was elevated in unilaterally and bilaterally eyestalk-ablated animals (54.1 and 106.9 ng/gland, respectively). When extracts of the sinus gland (SG), a source of neuropeptides in the eyestalk, were injected into bilaterally ablated lobsters, hemolymph levels of MF dropped to undetectable levels in 2 to 3 hr. The response to SG extract was dose dependent, and MF levels recovered by 12 to 24 hr after treatment. SG extract also lowered the MF content in the MO from 267.6 to 6.6 ng/gland after 4 hr. These results indicate that MF in the hemolymph and MO is negatively regulated by a factor(s) from the SG.

Two distinct genes encode two major isoelectric forms of insecticyanin in the tobacco hornworm, Manduca sexta

Insecticyanin is a blue pigment found in the epidermis and hemolymph of the tobacco hornworm, Manduca sexta. Two distinct full-length cDNA species were isolated and shown to encode the two major isoelectric forms of insecticyanin, the a form (INS-a) and b form (INS-b). Sequence analysis of the two cDNA clones, pE1-I1 and Pe3-I2, reveals that both contain an 618-bp open reading frame which predicts an 189-amino-acid protein and an 17-amino-acid signal peptide. Comparison of the deduced INS-a and INS-b proteins show 13 amino acid differences, of which six are conserved. Three amino acid substitutions are also found between the deduced INS-b sequence and the sequenced INS-b protein isolated from the hemolymph. Isolation and characterization of five genomic clones revealed that pE1-I1 and pE3-I2 come from two different genes. Both INS-a and INS-b genes have four exons interrupted by three introns at the same positions. The two genes share 93% nucleotide similarity in the coding region. Moreover, the 'TATA box' and 'CAAT box' are completely conserved in the putative promoter regions of the two genes. Primer extension revealed that both INS-a and INS-b genes begin their transcription at position -52 relative to their translation initiation codon, ATG. We conclude that the two genes are the result of gene duplication.

Acid-base changes on transfer between sea- and freshwater in the Chinese crab, Eriocheir sinensis

The time course of changes in hemolymph pH, PCO2 and bicarbonate concentration were followed in euryhaline Chinese crabs, Eriocheir sinensis, after transfer from seawater (SW) to freshwater (FW) and vice versa. In order to correlate these changes with the animal's ionic status, hemolymph osmolarity and Na+ and Cl- concentrations as well as net exchanges of acid-base equivalents with the external water were also measured. Transfer from SW to FW induced a metabolic alkalosis which peaked after 3 days and declined thereafter but remained significant by 29 days. Hemolymph PCO2 was markedly elevated in FW, thus moderating the increase in hemolymph pH. Osmolarity and Na+ and Cl- concentrations reached a new steady state at lowered values by 24-48 h and a significant outflux of acidic equivalents was measured only during the first 2 days. Transfer from FW to SW conversely induced a metabolic acidosis which was almost fully compensated by a marked hypocapnia. It is concluded that external acid-base exchanges coupled to ionic readjustments following a salinity transition cannot solely explain the associated acid-base disturbances, the metabolic component of which must also rely on tissular processes probably linked to cell volume regulation.

Isolation of cDNA clones coding for humoral lectin of silkworm, Bombyx mori, larvae

In the hemolymph of the silkworm, Bombyx mori, lectin with hemagglutinating activity against sheep red blood cells increases at larval-larval ecdysis and at spinning stage (Suzuki and Natori, 1983) and is induced by infection with cytoplasmic polyhedrosis virus. A Bombyx lectin polypeptide with molecular weight approx 280K is responsible for hemagglutinating activity, since antiserum raised against this polypeptide inhibited hemagglutinating activity. The site of synthesis of Bombyx lectin was determined by primary tissue cultures of fat body and hemocytes. A hemagglutinating activity assay demonstrated that hemocyte is responsible for the release of hemagglutinin into the culture medium. Isolation of cDNA clones coding for Bombyx lectin was carried out on the cDNA library prepared in an expression vector lambda gt11 starting with poly(A)+ RNA from spinning larval hemocytes. As a result of immunoscreening, several positive clones were obtained, and the cDNA clones were characterized.

Purification and properties of an ommochrome-binding protein from the hemolymph of the tobacco hornworm, Manduca sexta

A yellow-colored protein (YCP) was isolated from the hemolymph (i.e. blood) of fifth instar wandering stage larvae of Manduca sexta. The molecular mass of YCP was 31 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Gel filtration chromatography suggested that native YCP was a monomer. The absorbance spectrum of YCP revealed maxima at 278 and 405 nm. Chromophore was released from YCP through denaturation of the protein with methanol and chloroform. In neutral solution and in acid, the released chromophore showed the absorbance characteristics of an ommochrome: ommatin D. In addition, the chromophore was sensitive to treatment with arylsulfatase as would be expected for ommatin D. The amino acid composition and the N-terminal sequence of YCP were determined. The YCP polypeptide chain was found to be glycosylated. Carbohydrate analysis suggested that Man and GlcNAc were present in a 3:1 ratio. Circular dichroism indicated that YCP consisted of 68% beta-pleated sheet with no alpha-helices being detected. An in vitro incubation of larval fat body in the presence of [35S]methionine indicated that this organ was the site of synthesis. Ommochromes arise in insects as end products of the metabolism of tryptophan. It is well-documented that ommochromes occur in both the tissues and the excreta of insects. We propose that in M. sexta, one such tryptophan metabolite is found in the hemolymph associated with a specific protein.

Biologically active and amidated cecropin produced in a baculovirus expression system from a fusion construct containing the antibody-binding part of protein A

A synthetic antibody-binding part derived from protein A from Staphylococcus aureus was used as a fusion partner in a eukaryotic expression system employing Autographa californica nuclear polyhedrosis as a vector. This, in conjunction with an efficient signal sequence, facilitated the purification of the antibacterial peptide cecropin A from the medium of Spodoptera frugiperda cells infected with a recombinant virus. In order to increase further the concentrations of fusion protein, Trichoplusia ni larvae were used as host. Cecropin A could be obtained after cleavage of the fusion protein with CNBr. Biological activity as well as the correct structure including the C-terminal amide group was shown using electrophoresis with detection of antibacterial proteins and mass spectroscopy.

Invertebrate cytokines: tunicate cell proliferation stimulated by an interleukin 1-like molecule

Tunicate pharyngeal cells include lymphocyte-like cells and granular amoebocytes. They are involved in the specific allogeneic and phagocytic reactions of tunicates. Little is known about their regulation or control. A tunicate interleukin 1 (IL-1)-like fraction is shown to stimulate the proliferation of these cells in vitro. This fraction, designated tunicate IL-1 beta, was isolated from tunicate hemolymph by gel filtration and chromatofocusing chromatography. Mitogenic responses to tunicate IL-1 beta were dose dependent and could be eliminated rapidly by removing tunicate IL-1 beta from culture medium. A second tunicate hemolymph fraction had no effect on tunicate cell proliferation even though it exhibited IL-1-like activity in a mouse thymocyte proliferation assay. Phytohemagglutin did not act synergistically with either fraction. These data are discussed in terms of the function and evolution of IL-1-like molecules in invertebrates.

Neuroendocrine regulation of osmotic and ionic concentrations in the hemolymph of the freshwater shrimp Macrobrachium olfersii (Wiegmann) (Crustacea, Decapoda)

Putative neuroendocrine mediation of osmotic and ionic responses to acute exposure to high salinity medium was investigated in the freshwater shrimp Macrobrachium olfersii (Wiegmann). Homogenates of supra-esophageal or thoracic ganglia, prepared from shrimps exposed to seawater of 21% S for 6 hr, were injected into the abdominal musculature of shrimps previously exposed to freshwater and subsequently exposed to either freshwater or seawater (21% S). Osmotic, sodium, chloride, potassium, magnesium, and calcium concentrations were determined in hemolymph samples removed by intracardiac puncture at time = 0, 1, 3, or 6 hr after homogenate application. Control shrimps were injected with filtered seawater, isosmotic to the hemolymph, and treated similarly. In control shrimps, the osmotic, Na+, Cl-, K+, Mg2+, and Ca2+ concentrations in the hemolymph increased (P less than or equal to 0.05) after 1-hr exposure to seawater. In shrimps injected with homogenates of supra-esophageal ganglion and exposed to seawater, osmotic and ionic concentrations in the hemolymph did not vary with exposure time; in injected shrimps exposed to freshwater, Na+, Cl-, K+, and Mg2+ concentrations decreased (P less than or equal to 0.05) with time. In shrimps injected with homogenates of thoracic ganglion and exposed to seawater, hemolymph osmotic, K+, and Mg2+ concentrations increased (P less than or equal to 0.05); Na+, Cl-, and Ca2+ concentrations remained unchanged. In injected shrimps exposed to freshwater, hemolymph osmotic concentration alone increased (P less than or equal to 0.05) after 1 hr, all other ionic concentrations remaining unchanged. These data suggest that neurofactors apparently located within the ganglia of the central nervous system of M. olfersii may alter the apparent ionic permeabilities of this shrimp, depending on the salinity characteristics of the external medium. The data support the notion that invasion of the freshwater biotope by estuarine crustaceans has necessitated the evolution of specific physiological mechanisms capable of compensating for the osmotic dilution and ion loss typically encountered by such organisms.

Ecdysteroid receptors in the central nervous system of Manduca sexta: their changes in distribution and quantity during larval-pupal development

Ecdysteroids act initially by binding to nuclear and possibly also extranuclear receptors. The presence and expression of these receptors in the insect brain was investigated in the present study as a means of defining these neurons involved in ecdysteroid-regulated processes at different developmental stages. Early in the fifth larval stadium of Manduca sexta, when endogenous ecdysteroid levels are low, receptors for ecdysteroids in cerebral neurons are either absent or present at low levels. Receptors can be reliably detected only on day 0 and are not found again until day 3.5, at the beginning of the commitment peak in the ecdysteroid titer, when they occur in a small stage-specific population of cells. At this time, ecdysteroid receptors are found mainly in nuclei but are also observed at low levels in cytoplasm. By day 4.8, ecdysteroid receptors are exclusively nuclear, and the number of target cells has increased dramatically in several brain regions, including those with known neurosecretory cell groups. This population and organization of ecdysteroid target cells is constant up to day 6, after which time the number of target neurons declines. By day 7.8, only 10% of the number of labelled neurons seen on days 4.8-6.8 remain in peripheral areas. In the pupal brains, ecdysteroid receptors reappear in a new population of neurons. The results indicate changes in the genomic regulation of a varying neuron population by ecdysteroids during fifth stadium development.

Molecular cloning of cDNA for lipopolysaccharide-binding protein from the hemolymph of the American cockroach, Periplaneta americana. Similarity of the protein with animal lectins and its acute phase expression

A previous paper described the purification of a calcium-dependent lipopolysaccharide-binding protein from the hemolymph of Periplaneta americana (Jomori, T., Kubo, T., and Natori, S. (1990) Eur. J. Biochem. 190, 201-206). This paper describes the molecular cloning and characterization of cDNA for the LPS-binding protein. This protein was found to have a carbohydrate-recognition domain at its carboxyl terminus containing amino acid sequences that are conserved in various mammalian C-type lectins. It was also shown to contain an N-linked carbohydrate chain, and the amino acid residue carrying this chain was assigned as Asn at position 56 (23rd amino acid residue from the amino terminus). Northern blot analysis revealed the presence of multiple mRNAs that hybridized with this cDNA and transient increases in their content after injection of Escherichia coli into adult Periplaneta, suggesting that the LPS-binding protein plays a role in the acute phase response of this insect.

Mechanisms involved in parasitic castration: in vitro effects of the trematode Prosorhynchus squamatus on the gametogenesis and the nutrient storage metabolism of the marine bivalve mollusc Mytilus edulis

The mechanisms involved in the parasitic castration of the marine mussel Mytilus edulis by the trematode parasite Prosorhynchus squamatus Odhner, 1905, have been investigated in vitro with two bioassays employing dissociated host tissues. There is no conclusive evidence that P. squamatus affects the secretion of two host neuroendocrine factors, viz., gonial mitosis-stimulating factor and glycogen mobilization hormone, involved in the gametogenesis/nutrient storage cycles of the mussel. In contrast, extracts of P. squamatus sporocysts and cercariae significantly stimulated glycogen mobilization in host glycogen cells and strongly inhibited host gonial mitosis. A gonial mitosis-inhibiting factor (GMIF) was found in the hemolymph of parasitized mussels. The existence of an endogenous GMIF in mantle tissue of uninfected mussels has been demonstrated. This factor appeared to be secreted into the hemolymph during the period of sexual maturity. Whether the parasite acts directly on the host gonia, or by provoking the liberation of this endogenous GMIF, has yet to be ascertained. It would appear, however, that the parasite acts directly on host glycogen cells.

Complete cDNA and gene sequence of the developmentally regulated arylphorin of Calliphora vicina and its homology to insect hemolymph proteins and arthropod hemocyanins

Two cDNA libraries were prepared from poly(A)+ RNA isolated from fat bodies of last instar larvae of the blowfly Calliphora vicina. The libraries were probed with a genomic clone containing the coding sequence for an arylphorin subunit. Two cDNA clones as well as the genomic clone were mapped and their nucleotide sequences were determined. This revealed the presence of an open reading frame corresponding to a polypeptide with 759 amino acid residues. The deduced primary structure of Calliphora arylphorin and hemolymph proteins of other insect species and arthropod hemocyanine show nearly 30% identity. Highly conserved regions could be also identified.

[Osmotic and ionic homeostasis in insects and vertebrates under extreme influences on water-salt metabolism]

Dehydration which is accompanied by the decrease in the body mass of frogs and pigeons approximately by 10%, results in the corresponding increase in osmolality of the blood serum, as well as in the increase of sodium content of the latter. Under the same conditions, the increase in osmolality and sodium level in rats does not exceed 2% which is associated with the effective renal function. In caterpillars of the insect Vanessa urticae whose haemolymph is rich in organic osmotically active substances and potassium ions, in spite of dehydration and loss of the body mass, osmolality of the haemolymph slightly decreases, while cation concentration in the latter remains essentially constant. Experiments with injections of hyperosmotic solutions to rats and caterpillars, showed that these animals, belonging to different phylogenetic branches, exhibit highly effective physiological mechanisms of ionic and osmotic homeostasis.

Humoral factors reduce gap junction sensitivity to cytoplasmic pH. II. In vitro manipulations

Our previous studies demonstrated a diurnal rhythm in the response of gap junctions between crayfish giant axons to acidification and that the response was reduced after eyestalk ablation, sinus gland removal, or visual stress. In this paper we describe experiments to test whether compounds in the circulating hemolymph were responsible for modulation of the responsiveness gap junction channels to intracellular pH. In axons from destalked animals in which the hemolymph had been replaced with normal saline, the maximal junctional resistance after acidification (Rjmax) reached control values. In contrast, Rjmax reached only 30% of control after acidification in axons from animals that had been destalked but not perfused. Hemolymph drawn after eyestalk ablation was tested on axons from control animals. Treatment with hemolymph drawn 1 day after destalking resulted in control Rjmax values, while treatment with hemolymph drawn 7 days after destalking resulted in Rjmax values of only 5-40%. Similarly, pretreatment for 1 h with 100 microM ecdysterone resulted in low Rjmax values. These experimental results suggest that a circulating compound, most likely ecdysterone or a related molecule, regulates the physiological properties of gap junctions from crayfish lateral axons.

Lack of osmoregulation in Aplysia brasiliana: correlation with response of neuron R15 to osphradial stimulation

The exposure of Aplysia brasiliana to dilute seawater (90 and 80%) caused an increase of the relative weight, which returned to the original values after a few hours. Both osmotic and chloride concentrations of the hemolymph decreased on exposure to 80 and 90% dilute seawater, and after 3-h exposure there were no differences between the hemolymph and external media osmotic and chloride concentrations. In contrast to the clear regulatory capabilities reported for A. californica, A. brasiliana cannot maintain the osmolality of its body fluid in dilute media. In A. californica, osphradial receptors and neuron R15 are apparently involved in this regulatory mechanism. Perfusion of osphradium of A. brasiliana with dilute seawater (95-80%) did not affect electrical activity of the bursting neuron R15; perfusion with 70 and 60% seawater caused a transient increase in the duration of the quiescent period. In contrast to the model established for A. californica, in A. brasiliana no relationship was found between exposure of the osphradium to dilute media and electrical activity in neuron R15, which is in accordance with the lack of an osmoregulatory mechanism in this species. Such differences may reflect inherent differences in salinity tolerance between the two species.

Isolation of schistosomin, a neuropeptide which antagonizes gonadotropic hormones in a freshwater snail

The molecular mechanisms underlying parasite-induced inhibitory effects on host reproduction were studied in the freshwater snail, Lymnaea stagnalis, infected with the schistosome parasite Trichobilharzia ocellata. This combination is used as a model system for host-parasite interactions involved in schistosomiasis transmission. The female gonadotropic snail neuropeptide, calfluxin, was labelled with fluorescein isothiocyanate (FITC) and used as a ligand in receptor-binding studies on membranes of its target organ, the albumen gland. The binding of calfluxin to its receptor-guanyl-nucleotide-binding-protein (G-protein) complex was inhibited in vitro in the presence of haemolymph of schistosome-infected snails. This inhibition appeared to be established by a peptidergic factor called schistosomin. The receptor assay was used to identify schistosomin from haemolymph during subsequent purification and characterization steps. The peptide could also be purified from the central nervous systems of non-infected snails, indicating that it is produced by the snail itself and released into the haemolymph as a result of infection. Analysis by plasma-desorption mass spectrometry revealed that purified schistosomin has a molecular mass of 8780 Da.

Substrate-bound factors stimulate engorgement of growth cone lamellipodia during neurite elongation

The surfaces on which neurons grow greatly affect neurite elongation, but it is unclear how substrates influence the events within the growth cone that bring about elongation. Neurite elongation by Aplysia californica neurons in culture occurs through a series of transformations of the structures of the growth cone (Goldberg and Burmeister, J. Cell Biol., 103:1921-1931, 1986). The growth cone produces actin-rich protrusions, veils, and lamellipodia, which can then mature into the central body of the growth cone through the net advance of microtubules and membranous organelles from contiguous central regions, a process called "engorgement." Aplysia neurons form growth cones on poly-l-lysine-treated substrates, but their rate of neurite elongation is greatly enhanced on substrates additionally exposed to Aplysia hemolymph. The acute application of hemolymph to slowly growing neurites brings about a rapid acceleration of neurite elongation and engorgement. The enhancement of engorgement was effected with material eluted from hemolymph-treated substrates and was not seen when hemolymph was added to neurons cultured on hemolymph-treated substrates inactivated by exposure to UV radiation. Thus, we conclude that the rapid acceleration of engorgement caused by hemolymph is, in large part, a substrate-mediated effect. We propose that extracellular substrate molecules can modulate the rate of neurite growth through the regulation of the engorgement of lamellipodia. The microtubule disrupters colcemid and nocodazole inhibit the advance of vesicular elements into the lamellipodia following hemolymph treatment, but taxol, which promotes the polymerization and stabilization of microtubules, does not itself enhance engorgement. The microfilament disrupter cytochalasin B, however, stimulates engorgement. Our results suggest that regulating the resistance of the peripheral actin meshwork to penetration by microtubules and vesicles may be a mechanism by which substrate-attached molecules regulate neurite advance.

Influence of larval schistosomes on polysaccharide synthesis in albumin glands of Biomphalaria glabrata

An in vitro bioassay was used to examine [14C]glucose incorporation into polysaccharides in albumen glands (AGs) of susceptible M-line Biomphalaria glabrata infected with the NMRI strain of Schistosoma mansoni. Polysaccharide and galactogen synthesis were unaffected by larval trematode infection in AGs of snails at days 14, 21, and 28 post-infection (p.i.) when compared to uninfected controls. Further experiments were conducted to determine if daughter sporocysts, hypothesized to be primary mediators of parasitic castration in this system, were able to exert direct effects on synthetic activity of uninfected AGs via haemolymph-borne molecules or in vitro culture-generated larval excretory-secretory (ES) products. When AGs were incubated in the presence of infected snail haemolymph, significant differences in quantities of polysaccharides and galactogen were detected only in test organs incubated in day 28 p.i. haemolymph. Daughter sporocyst ES products generated during the first 48 h of culture caused a significant reduction in polysaccharide and galactogen synthesis in test organs. When ES products from days 3 to 6 of in vitro culture were tested similarly, no significant differences in either polysaccharide or galactogen synthesis were observed between control and test organs. These data demonstrate that daughter sporocysts are able to modulate a specific aspect of the reproductive activity of the snail host through haemolymph-borne molecules of host or parasite origin, or directly through in vitro culture-generated ES products.

The endogenous regulation of mosquito reproductive behavior

Most female mosquitoes require a meal of blood that provides protein for egg maturation. For reproduction to occur, two behavioral sequences are essential. One is concerned with finding a host for the blood meal and the other in finding a site on which to lay the eggs that result. Stimuli from both hosts and oviposition sites initiate the reproductive behaviors of host-seeking and pre-oviposition, respectively, that are discussed in this review. After sensory receptors perceive these stimuli, the central nervous system must integrate the information and associate it with a biologically appropriate response. Host-seeking appears to be the default behavior, expressed whenever host stimuli are present. However, if the female is successful in locating a host and ingesting blood, subsequent host-seeking is inhibited when the meal distends the abdomen above a certain threshold. Host-seeking inhibition continues during egg development as a result of a humoral mechanism even after the blood volume has been reduced by digestion. At the time when eggs are maturing and host-seeking is inhibited, pre-oviposition behavior predominates if the central nervous system receives oviposition site stimuli. This behavior is also initiated by a humoral factor. Several physiological states, including insemination, age, and nutrition, can modulate both host-seeking and pre-oviposition behaviors.

Interactions between different strains of Vibrio alginolyticus and hemolymph fractions from adult Mytilus edulis

The juvenile-bivalve pathogen Vibrio alginolyticus NCMB 1339 was toxic, in vitro, to hemocytes from adult Mytilus edulis. Toxicity was mediated by both washed bacterial cells and culture supernates. Washed cells of an environmental isolate of V. alginolyticus, Strain PS-1, were 2.5 times less toxic to Mytilus hemocytes, but this strain did produce a lethal extracellular factor(s) in broth culture, albeit at lower levels than V. alginolyticus NCMB 1339. Hemolymph fractions from Mytilus exerted a reciprocal toxic effect on the bacteria. Hemocytes were responsible for most of this bacteriocidal activity and toxic oxygen intermediates were involved in the phagocytic defense mechanisms of these cells.

Increased insecticidal effect by a recombinant baculovirus carrying a synthetic diuretic hormone gene

Genetically engineered insect viruses may be potential alternatives to conventional chemical insecticides. A recombinant gene for the diuretic hormone of the tobacco hornworm, Manduca sexta, has been introduced into a baculovirus, Bombyx mori nuclear polyhedrosis virus (BmNPV). When silkworm larvae were injected with the resulting recombinant BmNPV, the diuretic hormone was expressed, causing a strong alteration in larval fluid metabolism. The recombinant virus killed infected larvae about 20% faster than the original virus.

Oxygen-sensitive chemoreceptors in the branchio-cardiac veins of the crayfish, Astacus leptodactylus

Oxygen-sensitive activity was recorded from the branchial nerve of the crayfish Astacus leptodactylus in vitro. After the podobranchial and arthrobranchial nerves branch off to the gill, the branchial nerve terminates in the branchio-cardiac vein wall and its surroundings. When the former 2 branches were cut, irregular spontaneous activity could be recorded from a few fiber preparations innervating the branchio-cardiac vein. The branchio-cardiac vein was superfused or perfused with hypoxic or hyperoxic Ringer solution. Impulse frequency increased in response to hypoxia and decreased in hyperoxia. NaCN and almitrine strongly stimulated nerve activity. Baroreceptor activity was also observed. These response characteristics demonstrate that these receptors are Heymans-type chemoreceptors.

Hemolymph oxygen transport during environmental hypoxia in the shore crab, Carcinus maenas

Pre- and postbranchial blood was sampled from crabs, Carcinus maenas, in control normoxic conditions and after 3, 24 and 72 hours exposure to hypoxic water (PWO2 = 30 Torr) at 15 degrees C. Oxygen partial pressures, pH and the concentrations of L-lactate, urate and hemocyanin were measured and an in vitro relationship between P50 and pH was determined on a pooled sample for each series, allowing an estimation of the average in vivo oxygen affinity. In separate experiments, in vitro additions of urate was found to increase hemocyanin oxygen affinity in dialyzed hemolymph. In normoxia acclimated animals, high PaO2 values (107 +/- 8 Torr) prevailed and oxygen transport relied mainly on physically dissolved oxygen (80%). During hypoxic exposure, the fall of both PaO2 (down to 8-17 Torr) and PvO2 (4-8 Torr) was accompanied by an increase in in vivo hemocyanin oxygen affinity (delta P50 = -3 to -6 Torr, compared to normoxic blood). This increase was almost fully explained by the concomitant action of elevated blood pH, urate concentration and, to a lesser extent, L-lactate concentration. As a result, the difference between pre- and postbranchial oxygen concentration was maintained, or even increased, during hypoxia, the major part of the oxygen being transported as oxyhemocyanin (94-98%). We conclude that pH and urate are the most effective modulators in enhancing oxygen binding to hemocyanin during moderate ambient hypoxia. Whether an increase in hemocyanin oxygen affinity is essential to hypoxia adaptation in crustaceans is discussed.

Selected decrease of haemocytes of the freshwater snail Planorbarius corneus (L.) (Gastropoda, Pulmonata) after bacteria injection

The decrease of haemolymph phagocytic cells (SH) in Planorbarius corneus after bacterial injection seems to be mediated by humoral factor(s) released into the haemolymph. SH show different adhesiveness in vitro in the presence of bacterial metabolic products.

Overall study of the in vitro plasma clotting system in an invertebrate, Liocarcinus puber (Crustacea Decapoda): considerations on the structure of the Crustacea plasma fibrinogen in relation to evolution

An overall study of the in vitro plasma coagulation system in the crab Liocarcinus puber has been carried out using various analytical methods, namely thromboelastography, spectrophotometrical examination, and a new one based on changes of the mechanical impedance of the developing clot. From the results reported here the clotting pattern in this species appears surprisingly complex for an invertebrate and unexpectedly closer to that of the vertebrates. Indirect evidences suggest that the fibrinogen polypeptide chains in this species and very likely in the other crustacean, are very different from those of the vertebrates. This would imply that crustacean and vertebrate fibrinogen would have diverged from one another in a far remote past, far beyond the individualization of the vertebrate alpha chain, that is, over 1.5 million years ago.

Humoral factors released during trauma of Aplysia body wall. I. Body wall contraction, cardiac modulation, and central reflex suppression

1. Mechanical or electrical stimulation of isolated sections of body wall produced contractions that were graded with the intensity of the stimulus. Injury of body wall with shallow incisions produced extremely persistent contractions. 2. Long-lasting contraction of isolated body wall was also produced by brief application of "stimulated body wall wash" (SBW), sea water which was first washed through another section of body wall subjected to intense mechanical or electrical stimulation. Contractions were produced by SBW diluted to concentrations as low as 1% of the initial concentration. Contractions produced by prolonged application of SBW showed little fatigue, tachyphylaxis, or desensitization. 3. SBW caused contraction of isolated sections of body wall from all regions of the body, including tail, parapodia, siphon, purple gland, rhinophores, and anterior tentacles. SBW also caused contraction of isolated lateral columellar muscle and of the gill. 4. 30 mM CoCl2 blocked the release of contractile factors into electrically stimulated body wall and reduced but did not abolish contractile responses of unstimulated body wall to perfused SBW. SBW contractions were unchanged by disconnection of the perfused tissue to the CNS. 5. Hemolymph collected from the neck of an intact donor following strong electrical stimulation of the tail or excision of a parapodium ('stimulated hemolymphh, SHL) caused long-lasting contractions which were larger than those produced by control hemolymph (CHL) collected prior to stimulation of the donor. 6. Similarities between body wall contractions produced by SHL and by SBW, including their occurrence in 30 mM CoCl2, suggest that some of the contractile activity in SHL may be directly released from traumatized body wall. 7. SHL caused significantly greater cardioacceleration of the isolated heart than did CHL. Similarities between the cardioacceleration produced by SHL and by SBW suggest that a source of cardiac activity in SHL may be traumatized body wall. 8. SBW suppressed the gill-withdrawal reflex when applied selectively to the sheathed or desheathed abdominal ganglion. SBW-induced suppression was associated with significant reduction of evoked spike activity in identified gill motor neurons. SHL collected 1-2 h after noxious stimulation caused weak but significant suppression of the gill-withdrawal reflex when applied to the fully sheathed abdominal ganglion.

Humoral factors released during trauma of Aplysia body wall. II. Effects of possible mediators

1. Preliminary, general chemical characteristics of substances in artificial sea water (ASW) washed through stimulated body wall (SBW) and in hemolymph taken from noxiously stimulated animals (SHL) were consistent with those of classical neurotransmitters, amino acids, and small- to medium-sized peptides. 2. 5-Hydroxytryptamine (5HT) and acetylcholine (ACh), unlike SBW and SHL, caused relaxation when perfused into isolated body wall. FMRFamide produced a biphasic response--brief contraction followed by prolonged relaxation. 3. Small cardioactive peptide (SCPB) caused body wall contractions similar to those produced by SBW and SHL, except that SCPB contractions displayed more desensitization and were completely blocked by 30 mM CoCl2. SCPB and SBW contractions were synergistic. 4. Dopamine caused persistent body wall contractions similar to those of SBW and SHL. Dopamine contractions were reduced but not blocked by 30 mM CoCl2. Unlike SBW activity, dopamine activity was reduced by alkalinization. 5. Glutamate and taurine produced strong but usually short-lasting body wall contractions. Adenosine, octopamine, arginine vasotocin, and cholecystokinin (CCK-8) caused weak or variable contractions. Met-enkephalin and somatostatin caused no obvious body wall responses. 6. When superfused over the fully sheathed abdominal ganglion, FMRFamide, met-enkephalin, glutamate, aspartate, and taurine reduced the magnitude of the gill-withdrawal reflex elicited by siphon nerve stimulation. 7. Taken together with earlier results, these data suggest a preliminary framework for trauma signal pathways. It is proposed that stress hormones (perhaps including FMRFamide, SCPs, 5HT, and dopamine) are released into hemolymph from neuroendocrine cells. Effective amounts of active intracellular solutes such as amino acids may also be released by extensive cellular rupture. Various humoral signals produce slow effects that contribute to hemostasis, balling up, increased cardiac output, and reflex suppression.