Variations of somatostatin-like immunoreactivity in the circumoesophageal ganglia, the hepatopancreas, the mantle edge, and the hemolymph of shell-repairing snails (Helix aspersa)

Immunocytology and radioimmunoassays demonstrate the presence of immunoreactive somatostatin-like (IR-SOM-LI) material in the tissues of young or adult snails Helix aspersa bred under short or long day in controlled artificial conditions. Neurosecretory cells in the circumoesophageal ganglia and in the digestive gland, small fibers in the hepatopancreas, and small granules in the mantle epithelial cells are immunoreactive toward antisomatostatin. In all experimented animals shell fractures induce variations of the IR-SOM-LI concentrations in all assayed tissues whatever the lighting conditions were underwent. These findings support the hypothesis that in Helix one or more substances related to the vertebrate tetradecapeptide is (are) involved in the repair processes but that the storage and the metabolism may be different during the biological cycle of the snails. These results are compared with those previously published using different gastropods and different methods.

A family of bacteria-regulated, cecropin D-like peptides from Manduca sexta

Manduca sexta larvae respond to bacterial challenge by synthesizing a set of antibacterial hemolymph proteins. We have purified and sequenced three members of a family of cecropin D-like bactericidal peptides and isolated a cDNA clone complementary to a closely related bactericidin. Results obtained by Northern hybridization and RNase protection analysis showed that the increased synthesis of bactericidins is due to induction of their mRNA levels and that the synthesis of these peptides is not strictly tissue-specific, in contrast to previous beliefs. Although fat body was a richer source, the relative amounts of bactericidin mRNA were significant in seven other tissues examined.

The development of transmission at an identified molluscan synapse. I. The emergence of synaptic plasticities

1. A monosynaptic, chemical synapse exists between two identified neurons in the subesophageal ganglia of the pulmonate mollusc, Achatina fulica. The snail undergoes a direct development, i.e., there is no intervening metamorphic period. The presynaptic (V2) and postsynaptic (RPr1) cells are two of the largest neurons found in the ganglia. The development of transmission at this synapse was studied from the last one-third of embryonic life to adulthood. 2. Synaptic transmission was studied by eliciting an action potential in V2 and recording the resultant excitatory postsynaptic potential (EPSP) in RPr1. In a train of repetitive stimuli, the ratio of the mean amplitude of the second EPSP to that of the first EPSP (EPSP2/EPSP1) is always greater than 1, indicating that short-term facilitation is present at all developmental ages studied. Following the initial short-term facilitation, embryonic synapses undergo a profound synaptic depression. Postembryonically there is a progressive increase in the amount of frequency facilitation with age, suggesting that the synapse shows a developmental trend towards an increased capacity for transmitter release. 3. In contrast to the progressive growth of frequency facilitation, the amplitude of the first EPSP in a series of responses (EPSP1) is not significantly related to age. 4. When transmitter release is reduced to approximately 25% of normal levels by a low-Ca2+/high-Mg2+ saline, the synaptic depression that is observed in the younger synapses disappears and is replaced by an adult-like frequency facilitation. 5. The adult synapse displays a phenomenon similar to posttetanic potentiation, which we refer to as the "retention of frequency facilitation." If an initial train of 150 stimuli at 0.2 Hz is followed by a second, identical train after an interval of 1 h, the postsynaptic response is greater during the second train than during the first. This phenomenon only becomes apparent in the second month after hatching, indicating that this separate synaptic plasticity develops at a different rate than does frequency facilitation.

Purification of three antibacterial proteins from the culture medium of NIH-Sape-4, an embryonic cell line of Sarcophaga peregrina

Three antibacterial proteins were purified from the culture medium of NIH-Sape-4, an embryonic cell line of Sarcophaga peregrina (flesh fly). Sequencing studies showed that two of these proteins belong to the sarcotoxin I family, potent antibacterial proteins purified from the hemolymph of Sarcophaga larvae, whereas the other protein, named sapecin, is a new protein consisting of 40 amino acid residues including 6 cysteine residues. Unlike sarcotoxin I, sapecin preferentially represses the growth of various Gram-positive bacteria. The proteins of the sarcotoxin I family produced by this cell line were found to have carboxyl-terminal glycine, whereas sarcotoxin I in the hemolymph has amidated amino acids. This suggests that the embryonic cells lack an enzyme that cleaves off carboxyl-terminal glycine to form a new amidated carboxyl terminus.

[The electrolyte content of the body of insects, ascidians, fishes, amphibians and mammals and its dynamics in ontogeny]

In animals in which sodium is a predominant cation of the blood serum or haemolymph (rat, newt Triturus vulgaris, sturgeon Acipenser güldenstädti, herring Clupea pallasi, ascidian Goniocarpa rustica), its content in the body amounts up to a half of the total bulk of electrolytes; in insects with potassium type of the haemolymph, the share of sodium is equal to 6.4%. In animals of the same species, total electrolyte content (sodium, potassium, calcium, magnesium) and the relationship between separate ions were found to be remarkably constant. During ontogenetic development of the sturgeon and herring, as well as in rat embryos beginning from the 15th day of gestation, the ratio between separate cations exhibits significant conservatism.

A gonial mitosis-stimulating factor in cerebral ganglia and hemolymph of the marine mussel Mytilus edulis L

A gonial mitosis-stimulating factor produced by the cerebral ganglia of the mussel Mytilus edulis has been demonstrated. This factor induces an increase of [3H]thymidine incorporation in the DNA of isolated mantle cells. Dose-response data are obtained with the methanol phase of an acidic ganglia extract. The rate of [3H]thymidine incorporation is compared with aspartate transcarbamylase specific activity, another bioassay previously described to estimate mitotic activity. This heat-stable mitogenic factor appears to have a molecular weight of less than 5000 Da. A gonial mitogenic factor is also found in the hemolymph and circulatory cells.

Liquid chromatographic procedures for the analysis of compounds in the serotonergic and octopamine pathways of lobster hemolymph

High-performance liquid chromatography, with serial electrochemical and ultraviolet detectors, was used with a reduced activity catecholamine C18 column to separate and quantify compounds important in the serotonergic and octopamine pathways in lobster hemolymph. The chromatographic mobile phase was composed of potassium dihydrogenphosphate buffer, trichloroacetic acid, sodium dodecyl sulfate, the sodium salt of ethylenedinitrilotetraacetic acid and the organic solvents, acetonitrile and methanol. The compounds serotonin, 5-hydroxyindoleacetic acid, tryptophan, 5-hydroxytryptophan, tryptamine, melatonin, octopamine and tyrosine were well resolved within 13 min. Good electrode maintenance, the use of a silica gel precolumn and careful sample preparation were necessary to give a stable baseline, high resolution of these compounds and reproducibility of retention times and peak heights. The electrochemical detector extended the range of detection to the picogram level. Because of the instability of the solutes and of the chromatographic baseline, sample preparation procedures were investigated. Deproteinization with ammonium sulfate gave the best recovery of the compounds of interest and the most stable baseline with the electrochemical detector. Peaks in the hemolymph were characterized by addition of standards, dual detection (electrochemical and ultraviolet) and the enzyme peak shift technique. With this methodology, important endogenous neurohormones in the hemolymph of lobsters can be quantitatively determined with respect to the molt cycle.

Insect lipid transfer particle catalyzes diacylglycerol exchange between high-density and very-high-density lipoproteins

Facilitated diacylglycerol exchange between Manduca sexta [3H]diacylglycerol-labeled high-density lipophorin and Heliothis zea very-high-density chromolipoprotein was studied. M. sexta lipid transfer particle was employed in assays which measured exchange of [3H]diacylglycerol. Following incubations with lipid transfer particle, donor and acceptor lipoproteins were reisolated by density-gradient ultracentrifugation to determine facilitated exchange. The reaction was limited to diacylglycerol exchange, while donor or acceptor particle apoprotein exchange did not occur. Lipid analysis of donor and acceptor lipoproteins after the lipid-exchange reaction revealed that the labeled diacylglycerol remained unchanged. Lipid transfer particle-catalyzed diacylglycerol exchange was linear up to 0.3 micrograms lipid transfer particle protein in a standard assay and exchange occurred at a rate of 2.5 micrograms diacylglycerol min-1.micrograms-1 lipid transfer particle protein. The assay method was used to show that the hemolymph concentration of lipid transfer particle increased during development.

Isolation and primary structure of a neuropeptide hormone from Heliothis zea with hypertrehalosemic and adipokinetic activities

A neuropeptide was isolated from the corpora cardiaca of the corn earworm moth Heliothis zea, and purified by sequential gradient elution in three reversed phase-high performance liquid chromatographic steps. The primary structure, pGlu-Leu-Thr-Phe-Ser-Ser-Gly-Trp-Gly-Asn-NH2 was determined by automated gas-phase Edman degradation of the peptide deblocked with pyroglutamate aminopeptidase, and confirmed by fast atom bombardment mass spectrometry. The hormone was synthesized and the natural and synthetic peptides had identical chromatographic and spectroscopic properties. Both natural and synthetic hormones caused the elevation of trehalose and lipid levels in the hemolymph of adult H. zea males.

Purification of a beta-1,3-glucan recognition protein in the prophenoloxidase activating system from hemolymph of the silkworm, Bombyx mori

The plasma fraction (referred to as plasma-CPB) of silkworm hemolymph, from which a protein with affinity to beta-1,3-glucan was specifically removed according to Yoshida et al. (Yoshida, H., Ochiai, M., and Ashida, M. (1986), Biochem. Biophys. Res. Commun. 141, 1177-1184), was used to develop a method for quantitating the beta-1,3-glucan recognition protein of the prophenoloxidase activating system. In principle, a sample was judged to contain beta-1,3-glucan recognition protein when that sample could restore the ability of the system in plasma-CPB to be triggered by beta-1,3-glucan. Purification procedures for the recognition protein from silkworm hemolymph consisted of fractionation with ammonium sulfate, chromatography on DEAE-Toyopearl, Affi-Gel-heparin, and Mono Q and Superose 12 on the fast protein liquid chromatography system of Pharmacia LKB Biotechnology Inc. About 2.03 mg of beta-1,3-glucan recognition protein was obtained from 300 ml of hemolymph. The purified beta-1,3-glucan recognition protein was homogeneous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing-polyacrylamide gel electrophoresis. beta-1,3-Glucan recognition protein had a molecular mass of 62 kDa composed of a single polypeptide and an isoelectric point of pH 4.3. It bound to curdlan beads (composed of beta-1,3-glucan with average particle size of 80 micron) in the absence of divalent cation, whereas its binding to glucans with beta(1----4)- or alpha(1----6)-glycosidic linkages was not detected under the experimental conditions. Elution of the beta-1,3-glucan recognition protein bound to curdlan beads could be achieved under strongly denaturing conditions (after incubation of the beads with sodium dodecyl sulfate and beta-mercaptoethanol in boiling water for 5 min), but elution at room temperature was poor. Since beta-1,3-glucan recognition protein is the only protein in silkworm plasma with strong affinity to beta-1,3-glucan and endows the prophenoloxidase activating system in plasma-CPB with the ability to be triggered by beta-1,3-glucan, it was concluded that binding of the purified beta-1,3-glucan recognition protein with beta-1,3-glucan causes the triggering of the prophenol-oxidase activating system in silkworm plasma. However, the nature of the activity that is generated as the result of binding is not yet known. The purified beta-1,3-glucan recognition protein bound to beta-1,3-glucan did not hydrolyze appreciably any of the 26 commercially available peptidyl-7-amino-4-methylcoumarins, substrates for various proteases.

Purification and characterization of two trypsin inhibitors from the hemolymph of Manduca sexta larvae

Trypsin inhibitory activity from the hemolymph of the tobacco hornworm (Manduca sexta) was purified by affinity chromatography on immobilized trypsin and resolved into two fractions with molecular weights of 14,000 (M. sexta hemolymph trypsin inhibitor (HLTI) A) and 8,000 (HLTI B) by molecular sieve chromatography on Sephadex G-75. Electrophoresis of these inhibitors under reducing conditions on polyacrylamide gels gave molecular weight estimates of 8,300 for HLTI A and 9,100 for HLTI B, suggesting that HLTI A is a dimer and HLTI B is a monomer. Isoelectrofocusing on polyacrylamide gels focused HLTI A as a single band with pI 5.7, whereas HLTI B was resolved into two components with pI values of 5.3 and 7.1. Both inhibitors were stable at 100 degrees C and pH 1.0 for at least 30 min. HLTIs A and B inhibited serine proteases such as trypsin, chymotrypsin, and plasmin, but did not inhibit elastase, papain, pepsin, subtilisin BPN', and thermolysin. In fact, subtilisin BPN' completely inactivated both inhibitors. Both inhibitors formed low-dissociation complexes with trypsin in a 1:1 molar ratio. The inhibition constant for trypsin inhibition by HLTI A was estimated to be 1.45 x 10(-8) M. The HLTI A-chymotrypsin complex did not inhibit trypsin; similarly, the HLTI A-trypsin complex did not inhibit chymotrypsin, indicating that HLTI A has a common binding site for both trypsin and chymotrypsin. The amino-terminal amino acid sequences of HLTIs A and B revealed that both these inhibitors are homologous to bovine pancreatic trypsin inhibitor (Kunitz).

Schistosomin: a pronase-sensitive agent in the hemolymph of Trichobilharzia ocellata-infected Lymnaea stagnalis inhibits the activity of albumen glands in vitro

The schistosome parasite, Trichobilharzia ocellata, nearly completely inhibits the reproductive activity of its intermediate host, Lymnaea stagnalis. The synthetic activity of albumen glands of infected snails at day 35 postinfection (p.i.) is only 1% of the control value. The parasite acts by humoral means. We tested the hypothesis that (a) specific humoral agent(s) is (are) involved and refer to this (these) agent(s) as schistosomin. The presence of schistosomin in the hemolymph of infected snails was investigated by using galactogen synthesis in albumen glands as an in vitro bioassay. The synthetic activity of albumen glands of noninfected snails decreased by about 50% during a 1-h incubation in the hemolymph of infected snails. This inhibition is attributed to schistosomin. Based on these results, with the present bioassay schistosomin appears in the hemolymph between days 28-36 p.i. onwards. Schistosomin is heat-stable (100 degrees C) and pronase-sensitive, and therefore it might have a peptide nature. Schistosomin suppresses the stimulating action of the female, gonadotrophic dorsal body hormone at relatively low doses, which suggests that it may compete with this hormone for the same receptors. The development of two other bioassays for schistosomin in our laboratory is discussed.

Heterogeneous glycosylation of Musca domestica arylphorin

Two distinct fractions of Musca domestica arylphorin were isolated by affinity chromatography on Concanavalin A-Sepharose column. The results show that in the hexameric arylphorin that do not bind to the lectin there is no Concanavalin A binding subunit and in the majority of the hexamers that bind to the lectin there is only one subunit with Concanavalin A binding site. The results indicate that the carbohydrate moiety of the arylphorin is not involved in its specific uptake by the fat bodies and integument.

Detection and microsequencing of juvenile hormone-binding proteins of an insect by the use of an iodinated juvenile hormone analog

An [125I]iodinated juvenile hormone (JH) analog can be used as a sensitive and highly selective probe for the visualization of high-affinity, (JH)-specific binding proteins from insect hemolymph samples. The proteins can be detected in their native form using a two-dimensional (isoelectric focusing then native gradipore gel) separation of the crude protein mixture containing the 125I-labeled iodinated JH analog. The proteins can be transferred to activated glass fiber paper by electroblotting, and the location of the bound gamma-emitter can be found by exposure of the dried gel or the electroblot to X-ray film. The radiolabeled protein spot can be excised from the Coomassie-stained glass fiber paper and subjected directly to gas-phase N-terminal amino acid sequencing. This non-destructive, non-denaturing technique may have wide applicability in identifying and sequencing ligand-specific binding proteins in complex mixtures.

Trichobilharzia ocellata: interference with endocrine control of female reproduction of Lymnaea stagnalis

Calfluxin (CaFl), one of the gonadotropic hormones of Lymnaea stagnalis, stimulates the influx of Ca2+ into the mitochondria of the cells of the albumen gland, one of the accessory sex organs of the snail. This effect is suppressed in glands of noninfected snails by an agent (schistosomin) present in the hemolymph of snails infected by Trichobilharzia ocellata as shown in in vitro experiments. The agent is present from 6 weeks postinfection onward. Ca2+ deposits in the mitochondria were demonstrated with the ultracytochemical antimonate precipitation technique. The percentage of Ca2+-positive mitochondria was taken as a measure for the effects of CaFl. This percentage appeared to be greatly reduced when glands were incubated in serum of infected snails (Sinf). The data showed that Ringer incubations can serve as controls for experiments with serum: no differences were found between Ringer incubations and incubations in either fresh or frozen serum of noninfected snails. Schistosomin was not affected by freezing, which enables cold storage of Sinf. The dose-response relationship of schistosomin shows that at a 1:2 dilution of Sinf with Ringer the response to CaFl was reduced more than 50%. Schistosomin is heat-stable and Pronase-labile, which indicates that it has a peptide nature. Probably schistosomin(s) is responsible for the reduction/cessation of fecundity in trematode-infected snails.

Regulation of the ecdysteroid titer of Manduca sexta: reappraisal of the role of the prothoracic glands

It is generally accepted that the prothoracic glands of insects produce ecdysone, which is converted by a 20-monooxygenase in peripheral tissues to the major molting hormone, 20-hydroxyecdysone. Incubation in vitro of the prothoracic glands of larval or pupal Manduca sexta in the presence of a hemolymph protein fraction (HPF) increased the ecdysteroid content of the medium almost 8-fold. A comparable increase was noted when HPF was added to medium preconditioned with prothoracic glands but from which the glands had been removed. We used a differential RIA to show that a major product of the prothoracic glands in vitro cross-reacts with antiserum (20-hydroxyecdysone-2-succinylthyroglobulin amide; H-2) that retains affinity to ecdysteroids having a modified A ring. However, this product did not bind to antiserum (ecdysone-22-succinylthyroglobulin amide; H-22) that has affinity mainly for ecdysteroids modified at the side chain. We employed radiolabeled precursor studies with prothoracic glands in vitro and a combination of analytical techniques (NMR, CD, MS) to demonstrate that the major ecdysteroid release from the glands is a mixture of 2-dehydroecdysone and 3-dehydroecdysone (1:2), which is rapidly reduced to ecdysone in the presence of HPF. We postulate that the active component of HPF is 3 beta 3 beta (2 beta)-formin-3(2)-ketoecdysteroid reductase. These results may explain several anomalous observations pertaining to the molting of insect fragments in the absence of prothoracic glands and suggest a complex system for the control of insect molting and metamorphosis.

Lipid thermotropic transitions in Triatoma infestans lipophorin

The structure and lipid thermotropic transitions of highly purified lipophorin of Triatoma infestans were examined by several techniques: steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), cis-parinaric acid (cis-PnA) and trans-parinaric acid (trans-PnA), light scattering fluorescence energy transfer between the lipophorin tryptophan residues and the bound chromophores, DPH, trans-parinaric acid cis-parinaric acid, gel electrophoresis, and gel filtration. Fluorescence polarization of PnAs and DPH revealed a reversible lipid thermotropic transition in intact lipophorin at about 20 degrees C and 18 degrees C, respectively. In lipophorin, lipid dispersion fluorescence polarization of DPH detected a lipid transition approximately at 20 degrees C, while trans-PnA showed a gel phase formation at a temperature below 30 degrees C. Similar experiments in which trans-PnA was incorporated into diacylglycerols and phospholipids extracted from the lipophorin revealed gel phase formation below 30 degrees C and 24 degrees C, respectively. Light scattering measurements showed that lipophorin particles aggregate irreversibly at 45 degrees C, increasing the molecular weight, as determined by gel filtration on Sephacryl S-300, from 740,000 to values larger than 1,500,000. The particle aggregation did not change the physical properties of the lipophorin studied by fluorescence polarization, indicating that the aggregation is apparently a non-denaturing process. Energy transfer between the lipophorin tryptophans and the bound chromophores cis-PnA, trans-PnA, and DPA revealed a different location of the fluorescent probes within the lipophorin. Temperature-dependence on the energy transfer efficiency for all probes confirmed a change in the ordering of the lipophorin lipids at 24 degrees C.

Juvenile hormone regulation of mRNA levels for a highly abundant hemolymph protein in larval Trichoplusia ni

Several hemolymph proteins ranging in size from 73 to 76 kDa increase to very high levels just prior to metamorphosis in Trichoplusia ni (Lepidoptera). One of these proteins (pI = 5.8, Mr = 76,000) was selected for a study of hormonal regulation. The appearance of this protein could be suppressed in vivo by topical treatment with the juvenile hormone analog fenoxycarb. An antiserum for this protein was prepared and shown to react selectively with the 76-kDa protein in whole hemolymph. Translation of poly(A)-containing RNA from untreated larvae yielded the 76-kDa protein, whose identity was verified with the antibody, whereas mRNA from juvenile hormone analog-treated larvae did not. These data indicate that juvenile hormone acts to regulate the level of the mRNA of this hemolymph protein.

Oxygen binding characteristics of the hemocyanins of two deep-sea hydrothermal vent crustaceans

Effects of pH and temperature on hemocyanin oxygen binding were examined using dialyzed blood from the hydrothermal vent crustaceans Bythograea thermydron (Brachyura) and Alvinocaris lusca (Caridea); blood samples were dialyzed against physiological salines having the same inorganic ion concentration as the blood. Hemocyanin of dialyzed B. thermydron blood demonstrated the highest O2 affinity at 10 degrees C (P50 = 1.8, 3.4 and 4.5 Torr at pH = 8.01, 7.7 and 7.4, respectively), with lower affinities at both higher and lower temperatures for all experimental pH values. A moderate Bohr effect (delta logP50/delta pH = -0.34 to -0.67) was found at all experimental temperatures (2-20 degrees C, pH 7.4-8.01), and a CO2 effect, independent of the pH Bohr effect, was measured at 5 degrees C. Hill coefficients varied widely (n50 = 0.95-3.95) and did not appear to vary with temperature or pH. The hemocyanin oxygen binding properties of B. thermydron blood are not affected by dialysis against salines having the same inorganic ion composition as the blood. Hemocyanin of dialyzed blood from A. lusca demonstrated a reverse temperature effect and a large Bohr effect (delta logP50/delta pH = -0.77 at 5 degrees C, pH 7.4-7.7). Functional aspects of oxygen binding are discussed in relation to the hydrothermal vent environment, and in the context of recent work on crustacean hemocyanins.

Comparison of haemolymph proteins from Schistosoma mansoni (Trematoda)-susceptible and resistant Biomphalaria glabrata (Gastropoda)

1. Whole and haemoglobin (Hb)-depleted serum fractions from Schistosoma mansoni-resistant (10-R2) and schistosome-susceptible (PR albino, M-line) strains of Biomphalaria glabrata were studied using sodium dodecyl sulphate-polyacrylamide gel electrophoresis, immunoblotting and protein assays. 2. Whole serum of the PR albino strain had more total protein (11.4 +/- 1.9 mg protein/ml) than the 10-R2 strain (7.8 +/- 3.0 mg protein/ml). 3. There are specific differences in the polypeptide profiles of the Hb-depleted fractions between the 10-R2 and PR albino strains of B. glabrata. 4. Antibodies against whole 10-R2 or PR albino serum reacted similarly when incubated with whole or Hb-depleted snail sera although differences in staining intensities were observed. 5. Antibodies against snail Hb reacted with many proteins in whole sera and Hb-depleted fractions from both B. glabrata strains indicating that they may be Hb-associated polypeptides. 6. Polypeptides in whole or Hb-depleted snail serum are modified by reduction indicating the presence of disulphide bonds.

[Protein composition of the hemolymph of Biomphalaria glabrata (Mollusca, Gastropoda). Influence of the method of sampling and relation to the protein composition of different organs]

The blood composition of B. glabrata is analyzed by electrophoresis. Its proteic composition differs in relation with the blood sampling method. Most of the supplementary fractions also have been found in the gut, some proteins possibly come from the hepatopancreas, whereas others could have their origin in the albumen gland. The sampling method must be selected according to these observations.

Iron binding proteins and their roles in the tobacco hornworm, Manduca sexta (L.)

Manduca sexta larvae accumulate large amounts of iron during their larval feeding period. When 59Fe was fed to 5th instar larvae, it was evenly distributed among the hemolymph, gut and carcass until the cessation of feeding. By pupation 95% of the labelled iron was found in the fat body. In the adult a significant portion of this iron was found in flight muscle. Studies of the hemolymph disclosed two iron-containing proteins. The first was composed of a single polypeptide chain of 80 kD, containing one atom of iron. This protein bound ionic iron in vitro and was able to transfer this iron to ferritin when incubated with fat body in vitro. Therefore, it appeared to serve a transport function. The second protein had a molecular weight of 490 kD with subunits of 24 and 26 kD and contained 220 micrograms of iron/mg protein. Its chemical and ultrastructural characteristics were those of ferritin. These studies demonstrate the presence of both a transport protein and a unique circulating ferritin in Manduca sexta, the latter serving a storage function during development and possibly also a transport function.

Primary sequence analysis by fast atom bombardment mass spectrometry of a peptide with adipokinetic activity from the corpora cardiaca of the cricket Gryllus bimaculatus

The octapeptide AKH-G, isolated from the cricket Gryllus bimaculatus, stimulates lipid mobilization in both the cricket itself and in migratory locusts. The structure of AKH-G has been assigned by fast atom bombardment mass spectrometry (FABMS) as pGlu-Val-Asn-Phe-Ser-Thr-Gly-Trp-NH2, and it is most closely related to AKH II-S from Schistocerca species, which has a Leu2 unit. Synthetic AKH-G, prepared by solid phase techniques, had the same bioactivity as the natural substance. FABMS measurements, including high-resolution and metastable studies, were made employing 400-900 pmole of sample.

Boophilus microplus: passage of bovine immunoglobulins and albumin across the gut of cattle ticks feeding on normal or vaccinated cattle

Cattle were vaccinated with antigens from adult female Boophilus microplus and haemolymph was collected from female ticks which had engorged on these animals and on matched control cattle. Radio-immunoassay for bovine plasma proteins in haemolymph from ticks fed on control cattle showed low concentrations of IgG1 and albumin. There was a significant increase in bovine plasma proteins passing across the gut in ticks fed on vaccinated cattle, with an average of 150 times more albumin and four to five times more IgG1 in the haemolymph. Ticks with obviously damaged gut had the highest concentrations of bovine plasma proteins but apparently undamaged ticks from vaccinated cattle also had elevated protein concentrations.

A functional, thioester-containing alpha 2-macroglobulin homologue isolated from the hemolymph of the American lobster (Homarus americanus)

An alpha 2-macroglobulin-like protease inhibitor was isolated from the cell-free hemolymph of the american lobster (Homarus americanus) by ion-exchange chromatography and gel filtration. Whereas the undissociated molecule has a molecular weight of 342,000 as determined by ultracentrifugation studies, under reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the protein has a subunit molecular weight of 180,000. On the basis of this and other evidence, we conclude that the lobster protein is a dimer consisting of two disulfide-bonded monomers. The purified protein inhibits proteolytic enzymes but protects the esterolytic activity of trypsin toward low molecular weight substrates from inactivation by soybean trypsin inhibitor. The methylamine sensitivity of this activity suggests the presence of an internal thioester bond. This was confirmed by the covalent incorporation of [14C]methylamine, by the formation of Mr 55,000 and 125,000 autolytic cleavage fragments in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and, more directly, by the amino acid sequence of a tryptic peptide containing the putative thioester region. Whereas the N-terminal amino acid sequence (22 residues) of the protein revealed an overall identity of only 18% when compared with the human protein, the sequence of the thioester-containing peptide was highly conserved, both with respect to human alpha 2-macroglobulin and to other proteins having a thioester bond. The protein showed the "slow to fast" conformational change typical in alpha 2-macroglobulins in nondenaturing gel electrophoresis after treatment with trypsin, but not after incubation with methylamine.