An endopeptidase inhibitor, similar to mammalian alpha 2-macroglobulin, detected in the hemolymph of an invertebrate, Limulus polyphemus

A protease inhibitory activity has been detected in the hemolymph of the horseshoe crab, Limulus polyphemus. The inhibitor possesses many of the characteristics of vertebrate alpha 2-macroglobulin. The inhibitor, found in the high speed supernatant of Limulus plasma, is sensitive to mild acidification, inhibits a variety of prokaryotic and eukaryotic endopeptidases, and is sensitive to methylamine treatment. Although the inhibitor completely prevents the trypsin-mediated hydrolysis of protein substrates, the hydrolysis of a low molecular substrate by trypsin is unaffected by the inhibitor, a property characteristic of alpha 2-macroglobulin. The striking similarity of the inhibitor to vertebrate alpha 2-macroglobulin, coupled with the fossil record of Limulus, suggests that such protease inhibitors are ancient molecules.

Developmental and sex-dependent regulation of storage protein synthesis in the silkworm, Bombyx mori

The mechanism of sex-dependent expression of a major plasma protein, referred to as storage protein 1 (SP-1) was studied during development of the silkworm, Bombyx mori. SP-1 occurred in the hemolymph of the female as well as in the male larvae until the end of the fourth larval instar. In the last instar larvae, the amount of SP-1 in the hemolymph greatly increased in females, but markedly declined in males. The level of fat body mRNA for SP-1 reflected the developmental and sex-dependent changes in the hemolymph concentration of SP-1. The developmental patterns of hemolymph proteins in the third and the fourth instar larvae of sex-mosaic individuals were quite analogous to those observed in normal larvae at the same developmental stages. The hemolymph concentration of SP-1 at the last larval instar of the sex mosaics varied among individuals irrespective of the gonad compositions. In vitro culture of the fat body cells dissected from several locations of a sex-mosaic larva provided evidence that each fat body cell in a common hemolymph milieu synthesizes a high (female type) or a low (male type) level of SP-1 depending on the sex chromosome composition. The amount of vitellogenin in the hemolymph of the sex-mosaic pupae was in proportion to that of SP-1 at the last larval instar. From these results, it is suggested that the sex-dependent expression of SP-1 and vitellogenin in B. mori is genetically determined and developmentally regulated without participation of the reproductive organs or any sex-specific humoral factors.

Agglutinins in the horseshoe crab hemolymph: purification of a potent agglutinin of horse erythrocytes from the hemolymph of Tachypleus tridentatus, the Japanese horseshoe crab

Agglutinins from Tachypleus (Tachypleus tridentatus, the Japanese horseshoe crab) hemolymph were isolated by affinity chromatography on BSM-coupled Sepharose 4B. The agglutinins showed multiple species and were composed of eight heterogeneous subunits with molecular weights of 45,000, 42,000, 41,000, 39,000, 33,000, 29,000, 27,000, and 22,000 as determined by SDS-polyacrylamide gel electrophoresis. The affinity-isolated agglutinins were fractionated into four groups by gel filtration on a Fractogel TSK (Toyopearl) HW-65 column, and these were designated as Tachypleus tridentatus agglutinin (TTA)-I, -II, -III, and -IV in the order of elution. These agglutinins were demonstrated to be heterogeneous as judged by their specificity towards horse erythrocytes, subunit structures, and immunological properties. TTA-III showed a potent agglutination activity towards horse erythrocytes and was further purified by gel filtration on a Cellulofine GC-700 column. The purified TTA-III is a highly purified (46,000-fold) protein composed of homogeneous subunits (Mr, 42,000) as judged by SDS-polyacrylamide gel electrophoresis and immunological analysis.

Insulin-like peptides in the lobster Homarus americanus. I. Insulin immunoreactivity

Experiments were conducted to determine if insulin-like peptides are present in the lobster Homarus americanus. Peptides were found that bind specifically to bovine insulin antibodies in a modified vertebrate radioimmunoassay. Extracts of whole hepatopancreas, gut, and hemolymph contained insulin immunoreactivity (IRI) concentrations of 67.5, 14.0, and 11.0 ng, respectively, per 700-g lobster. No insulin immunoreactivity was detected in neurosecretory cells of the eyestalk. The highest immunoreactivity was measured in the hepatopancreas, in the same fractions of eluate which contained the highest immunoreactivity when a bovine insulin standard was passed through the same chromatographic column.

Purification and characterization of an antibacterial protein from haemolymph of Sarcophaga peregrina (flesh-fly) larvae

Three antibacterial proteins were induced when the body wall of Sarcophaga peregrina (flesh-fly) larvae was injured with a hypodermic needle. These proteins were separated and one was purified to homogeneity. The molecular weight of the purified protein was 5000 and its amino acid composition was similar to that of cecropins, which are antibacterial proteins in Hyalophora cecropia (cecropia moth) pupae. This protein was found to have bactericidal activity and to be effective at a concentration of 0.1 micrograms/ml against certain Gram-negative and Gram-positive bacteria.

Detection of snail hemocyanin in the whole hemolymph by serologically specific electron microscopy

This study demonstrates the applicability of the serologically specific electron microscopy (SSEM) technique in the detection of hemocyanin molecules in the whole hemolymph of the snail, Megalobulimulus ovatus. The results are positive and easily reproducible. The SSEM might be useful as a technique for taxonomic studies of snails as well as to study structural aspects of their hemocyanin molecules.

Insulin-like peptides in the lobster Homarus americanus. II. Insulin-like biological activity

The in vitro incorporation of [14C]glucose into glycogen in lobster muscle was used to measure insulin-like biological activity. Glycogenesis was significantly increased by the same hepatopancreas eluate which was previously found to have the greatest insulin immunoreactivity. Hemolymph but not gut extract also increased the rate of glycogenesis.

Insect immunity. Attacins, a family of antibacterial proteins from Hyalophora cecropia

Six closely related antibacterial proteins, attacins A-F, were isolated from the hemolymph of immunized pupae of the Cecropia moth, Hyalophora cecropia. Chromatofocusing separated attacins A-F, with isoelectric points between 5.7 and 8.3. Immunological experiments show that the attacins constitute antibacterially active forms of the previously isolated inducible immune protein P5. Their mol. wts., 20-23 K, are similar to that of protein P5, but significantly lower than 28 K found for preP5 synthesized in vitro (see accompanying paper). The six attacins can be divided into two groups according to their amino acid composition and amino-terminal sequences, attacins A-D constitute a basic group and attacins E and F an acidic one. Within each group the forms are very similar. The attacins efficiently killed Escherichia coli and two other Gram-negative bacteria isolated from the gut of a silk worm but they did not act on other Gram-positive and Gram-negative bacteria tested. Only growing cells of E. coli were attacked; cells suspended in phosphate buffer were inert. Besides the cecropins and lysozyme, the attacins represent a third class of antibacterial proteins in the humoral immune system of H. cecropia.

Measurement of Sarcophaga peregrina lectin under various physiological conditions by radioimmunoassay

Lectin induced in the hemolymph of Sarcophaga peregrina (flesh fly) larvae on injury of the body wall or on pupation was studied further by radioimmunoassay, focusing on the interaction between the lectin and hemocytes. It was found that the amount of lectin on the surface of hemocytes prepared from injured larvae increased with time after injury of the body wall. Radioiodinated lectin could bind to hemocytes prepared from injured larvae more effectively than those from normal larvae, indicating a difference in the affinities to lectin of hemocytes from these two sources. The lectin was found to be synthesized in the fat-body and then secreted into the hemolymph both on injury of the body wall and on pupation. A significant level of lectin was maintained in pupae during the entire pupal stage, but it decreased rapidly before emergence, and no lectin was found in newly emerged flies. Since the lectin greatly activated the activity of mouse bone marrow cells to kill Candida parapsilosis cells, the biological significance of humoral lectin in the defense mechanism was discussed from the ontogenic viewpoint.

Tube inserts as aids in preparative ultracentrifugation

Conventional preparative ultracentrifugation was modified by using inserts in the centrifuge tubes, causing a reduction of the time necessary to centrifuge a protein at reduced rotor velocity from suspension.

Non-respiratory haemolymph proteins in the vineyard snail Helix pomatia. Changes after phagocytosis in vivo

Haemolymph proteins from the vineyard snail Helix pomatia were studied by chromatographic and immune-electrophoretic techniques with the dual purpose of characterizing the normal composition of haemolymph and to look for possible opsonins. The oxygen-carrying proteins, alpha- and beta-haemocyanin, were by far the most abundant proteins, but at least three non-respiratory proteins could be demonstrated. We found consistent changes in the appearance of the immunoprecipitation pattern of these non-respiratory proteins after the injection of particulate foreign matter into the snail's circulation, and we suggest that they may be opsonins. We also found a haemagglutinin in haemolymph. It was present in very low concentration and was similar to, but not identical with the haemagglutinin which is present in the albumin gland.

Isolation and properties of vitellogenic ferritin from snails

The iron storage protein ferritin is the principal yolk protein in oocytes of the snails Planorbarius corneus L. and Lymnaea stagnalis L. This report gives an account of the isolation procedure and of some properties of snail ferritins. The isolation procedure includes a heat-denaturation step, gel filtration on Sepharose 6B and two ultracentrifugation steps followed by electrophoresis. Ferritins from both snails are highly reminiscent of vertebrate and plant ferritins in terms of heat stability, absorption spectrum and ultrastructure, and both share common antigen determinants with horse spleen ferritin. In different electrophoresis systems snail ferritins display considerable heterogeneity and microheterogeneity. Electrophoresis in the presence of sodium dodecyl sulphate (SDS) yields two major polypeptides with molecular weights of 19 000 and 24 000, which are interpreted to be authentic subunits of the ferritin molecule. Different organs and tissues of the snails differ in subunit composition. Midgut gland ferritin consists predominantly of the 19 000 Mr polypeptide, while in embryos only the 24 000 Mr band was found. No carbohydrates or lipids could be detected by staining acrylamide gels. Results from SDS/acrylamide electrophoresis, electrophoresis under non-denaturing conditions on gradient gels and from isoelectric focusing indicate that the ferritins of both snails are composed of at least two different types of ferritin that are tissue-specific. One ferritin is typical of somatic tissue (midgut gland) and is most probably a homopolymer of the 19 000 Mr subunit. The other ferritin is typical of oocytes, but since it is an exogenous protein it is also encountered in the midgut gland (the presumed site of yolk synthesis) and the haemolymph. Vitellogenic ferritin is either a homopolymer of the 24 000 Mr subunit or is predominantly composed of it. So far, there is no evidence for a precursor-product relationship between the two subunits.

Genic variation in abundant soluble proteins of Drosophila melanogaster and Drosophila pseudoobscura

Genic variation was surveyed for 20 proteins of Drosophila melanogaster and 18 proteins of D. pseudoobscura. Analysis was by extraction and one-dimensional polyacrylamide gel electrophoresis under nondenaturing conditions, followed by staining with Coomassie Brilliant Blue to detect soluble proteins present in relatively large amounts ("abundant soluble proteins"). D. melanogaster was polymorphic for 65% of its protein loci and an individual was heterozygous for 10% of its loci. The respective figures for D pseudoobscura were 61% and 11%. These estimates of genic variation fall between previously published estimates obtained for these species by one-dimensional electrophoresis of soluble enzymes and those obtained by two-dimensional electrophoresis of solubilized abundant proteins. However, variation for both species could be strongly partitioned between loci, on the basis of tissue and stage expression of the proteins. The results are discussed with respect to their bearing on the possibility that abundant proteins constitute a distinct class of proteins less polymorphic than soluble enzymes.

Dietary choline augments blood choline and cholinergic transmission in terrestrial mollusk Limax maximus

1. A radioenzymatic assay was used to determine the concentration of choline in the hemolymph of the terrestrial mollusk Limax maximus maintained on choline-enriched and choline-deficient diets. The levels of free choline in the slug's hemolymph varied with the availability of choline in the diet. The concentration of choline in the plasma of choline-enriched animals averaged 5.5 microM while the mean circulating choline level of choline-deprived slugs was 3.3 microM. The difference in choline levels between the two groups was statistically significant. 2. Neurophysiological measurements of transmission at the isolated cholinergic synapses between the salivary burster neuron (SB) and the salivary duct muscle (SD) showed that this synapse was sensitive to fluctuations in the external choline concentration within the physiological range. Increases in exogenous choline from 0.5 to 2.0 microM, from 2.5 to 5.0 microM, and from 5.0 to 15.0 microM were followed by increases in the amplitudes of SB-elicited junction potentials recorded from the SD by a focal extracellular electrode. 3. Thus, the SB-SD synapse is sensitive to the fluctuations in exogenous choline that can occur with a change in diet.

Activity of corpora allata, endocrine balance and reproduction in female Labidura riparia (Dermaptera)

The reproductive activity of Labidura riparia females involves, after a 5-day maturation stage, a regular alternation of ovarian cycles and egg-care stages averaging 10 days each. Vitellogenesis is characterized by an increase in the size of the corpora allata (CA) where structured SER bodies appear, and by a rise of juvenile hormone (JH III) content in the hemolymph which is followed by an increase in the level of ecdysteroids. During the egg-care periods, the CA are inactive; structured bodies generate autophagic vacuoles, the titer of JHs and later that of ecdysteroids in the hemolymph decreases and remains stationary. Ovariectomy causes hypertrophy and hyperactivity of the CA for about two months. Subsequently, the titer of JH decreases and old females may display parental behaviour; the level of ecdysteroids falls and remains unchanged. After cauterization of the pars intercerebralis (PI) of the protocerebrum, the ovarian activity stops, the ovary shrinks, the JHs rapidly disappear but ecdysteroids remain at the same or even higher levels than those of normal females of the same age. On the basis of these data, we postulate the existence of a center located in the PI, inhibiting the production of ecdysteroids, and of a stimulating center located outside this area. The PI also exhibits an allatotropic function.

Molecular evolution of Drosophila and higher Diptera. I. Micro-complement fixation studies of a larval hemolymph protein

LHP is a suitable protein for studying evolution in flies (Diptera). This blood protein, which occurs at high concentration late in larval development, was purified to homogeneity from 5 species of Drosophilidae and one species each of Tephritidae and Calliphoridae. Rabbit antisera to the purified LHPs allowed immunological comparisons to be made with the micro-complement fixation technique. Various indirect tests indicated that immunological distance is a reliable estimator of the degree of amino acid sequence difference between LHPs from different species. An evolutionary tree for the 7 LHPs was constructed from the immunological distances with the method of Fitch and Margoliash (1967) to provide the branching order and the method of Chakraborty (1977) to provide the branch lengths. A modified method of tree construction allowed LHPs from 10 additional species to be attached to this tree. The resulting LHP tree for 17 species agrees approximately in branching order with that based on Throckmorton's study of 60 anatomical traits. However, the ratio of anatomical change to LHP change along branches within the tree varies widely, confirming the independence of organismal and molecular evolution. The LHP tree thus provides a new perspective on evolution within and among the families of higher Diptera.

Identification of storage-protein messenger RNA of the fleshfly Sarcophaga peregrina

Storage-protein mRNA was found to be abundant in poly(A)-containing RNA extracted from the fat-body of third-instar larvae of Sarcophaga peregrina (fleshfly). This RNA sedimented at the position of 19S on sucrose-density-gradient centrifugation and the product of its translation in vitro was 75K protein (protein of mol.wt. 75 000), which was precipitated specifically with antibody against storage protein. This product was suggested to contain a signal sequence that is missing in mature storage protein. The poly(A)-containing RNA was also found to contain much of another mRNA coding for 25K protein (protein of mol.wt. 25 000), but the function of this protein is unknown.

Neuroendocrine control of Na+ balance in the fiddler crab Uca pugilator

The hemolymph ionic composition and unidirectional Na+ fluxes were analyzed in fiddler crabs (Uca) acclimated to 500 mosmol seawater. Eyestalkless crabs had lower hemolymph osmotic, Na+, and Cl- concentrations. The Na+ efflux was increased from 13.6 +/- 0.6 in control crabs to 19.6 +/- 1.3 mueq.g-1.h-1 in eyestalkless crabs; this increase was shown to be due to a higher Na+ permeability in eyestalkless crabs. Hemolymph Na+ in eyestalkless crabs was increased by an injection of eyestalk extract. The Na+ influx was increased from 11.1 in intact to 15.8 mueq.g-1.h-1 in eyestalkless animals. A kinetic study showed that 1) the influx was higher at all external Na+ concentrations in eyestalkless and intact-Na+-depleted crabs than in intact controls, and 2) the influx mechanism exhibited allosterism. The elevated Na+ influx in eyestalkless crabs was decreased by an injected eyestalk extract. An injected brain extract caused in increase in the Na+ influx in intact animals. It is concluded that the Na+ uptake mechanism is activated by decreasing the hemolymph Na+ concentration and that a brain hormone mediates the effect.

Limited proteolysis of the 94 000-dalton subunit of Panulirus interruptus hemocyanin; the carbohydrate attachment site

Limited proteolysis of the native monomeric 94-kDa subunit of Panulirus interruptus hemocyanin by trypsin, plasmin and subtilisin produces an 18-kDa fragment, a 71-kDa fragment and a small glycopeptide. In the plasmin digest a 23-kDa precursor of the 18-kDa fragment has been observed. Automatic Edman degradations demonstrated that the 18-kDa fragments have their origin at the N terminus of the 94-kDa subunit and incubations with carboxypeptidase A showed that the 71-kDa fragments originate from the C terminus. The glycopeptide is situated in between. The amino acid sequence of the glycopeptide has been determined. Its carbohydrate content accounts for the total carbohydrate of the 94-kDa subunit. All three proteases cleave the subunit at two positions within a very restricted area of the polypeptide chain, which indicates the presence of an exposed loop, carrying the carbohydrate chain, in the corresponding part the native molecule.