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The insect hemolymph protein HP19 mediates the nongenomic effect of ecdysteroids on acid phosphatase activity.

The activity of acid phosphatase (ACP) in insect fat bodies is stimulated by the steroid hormone 20-hydoxyecdysone (20E) in vivo. However, in fat bodies kept in culture, a factor from the hemolymph is required to enhance the ACP activity. We identified the factor as a protein with a molecular mass of 19 kDa (HP19) from the hemolymph of a lepidopteran insect, the rice moth, Corcyra cephalonica. Western analysis of hemolymph proteins with denaturing and non-denaturing PAGE using antibodies raised against HP19 suggest that this protein exists as a monomer. It is synthesized by the hind gut-associated lobular fat body of the larvae and is released into the hemolymph. The stimulatory effect of HP19 on the ACP activity is developmentally regulated and exhibits its maximal effect shortly before the onset of metamorphosis. We cloned the HP19 cDNA by immunoscreening a hind gut-associated lobular fat body cDNA expression library. Analysis of the amino acid sequence shows that HP19 belongs to the family of glutathione S-transferase (GST) like proteins. However, affinity-purified GST from Corcyra failed to show any mediation effect on 20E-stimulated ACP activity, and HP19 lacks GST enzymatic activity. Notably, HP19 mediates the hormone-stimulated ACP activity in intact fat body tissue and homogenates even in the presence of inhibitors of transcription and translation, suggesting a nongenomic mode of action. In addition, we show that HP19 inhibits the 20E-induced phosphorylation of the hexamerin receptor protein.

Acid Phosphatase↗

Quantitative comparison of caste differences in honeybee hemolymph.

The honeybee, Apis mellifera, is an invaluable partner in agriculture around the world both for its production of honey and, more importantly, for its role in pollination. Honeybees are largely unexplored at the molecular level despite a long and distinguished career as a model organism for understanding social behavior. Like other eusocial insects, honeybees can be divided into several castes: the queen (fertile female), workers (sterile females), and drones (males). Each caste has different energetic and metabolic requirements, and each differs in its susceptibility to pathogens, many of which have evolved to take advantage of the close social network inside a colony. Hemolymph, arthropods' equivalent to blood, distributes nutrients throughout the bee, and the immune components contained within it form one of the primary lines of defense against invading microorganisms. In this study we have applied qualitative and quantitative proteomics to gain a better understanding of honeybee hemolymph and how it varies among the castes and during development. We found large differences in hemolymph protein composition, especially between larval and adult stage bees and between male and female castes but even between adult workers and queens. We also provide experimental evidence for the expression of several unannotated honeybee genes and for the detection of biomarkers of a viral infection. Our data provide an initial molecular picture of honeybee hemolymph, to a greater depth than previous studies in other insects, and will pave the way for future biochemical studies of innate immunity in this animal.

Algorithms↗

Cold tolerance and the regulation of cardiac performance and hemolymph distribution in Maja squinado (Crustacea: decapoda).

Elevated Mg(2+) levels in the hemolymph ([Mg(2+)](HL)) of brachyuran crabs have recently been demonstrated to limit cold tolerance by reducing motor and circulatory activity. Therefore, the limiting function of elevated [Mg(2+)](HL) on circulatory performance and arterial hemolymph flow was investigated by the pulsed-Doppler technique in the spider crab Maja squinado during progressive cooling from 12 degrees to 0 degrees C. [Mg(2+)](HL) were reduced from control levels of 39.9 mmol L(-1) to levels of 6.1 mmol L(-1) by incubation in magnesium reduced seawater. At 12 degrees C cardiac output was 13.9+/-2.4 mL kg(-1) min(-1) and stroke volume 0.2+/-0.04 mL kg(-1) min(-1) in control animals. In [Mg(2+)](HL)-reduced animals cardiac output increased to 43.6+/-5.0 mL kg(-1) min(-1) and stroke volume rose to 0.6+/-0.1 mL kg(-1) min(-1). Temperature reduction in control animals revealed a break point at 8 degrees C linked to a major redirection of hemolymph flow from lateral to sternal and hepatic arteries. Cardiac output and heart rate dropped sharply during cooling until transiently constant values were reached. Further heart rate reduction occurred below 4.5 degrees C. Such a plateau was not detected in [Mg(2+)](HL)-reduced animals where the break point decreased to 6 degrees C, also indicated by a sharp drop in heart rate and cardiac output and the redirection of hemolymph flow. It is concluded that progressive cooling brings the animals from a temperature range of optimum cardiac performance into a deleterious range when aerobic scope for activity falls before critical temperatures are reached. Reduction of [Mg(2+)](HL) shifts this transition to lower temperatures. These findings support a limiting role for [Mg(2+)](HL) in thermal tolerance.

Acclimatization↗

Quantitative studies of host immunoglobulin G in the hemolymph of ticks (Acari).

A radioimmunoassay was used to measure the concentration of host immunoglobulin G (IgG) in the hemolymph of female hard and soft ticks. Hyalomma excavatum Koch, Rhipicephalus sanguineus Latreille, Ornithodoros tholozani (Laboulbene and Megnin), and O. moubata (Murry) were fed on rabbits immunized with ovalbumin; Argas persicus (Oken) was fed on chickens immunized with cytochrome 'C.' At 24 h after feeding, the concentration of antiovalbumin IgG in the hemolymph was 7 micrograms/ml for H. excavatum, 5 micrograms/ml for R. sanguineus, and 0.15 micrograms/ml for O. moubata; the percentage of intact IgG molecules was 30, 44, and 100%, respectively. Host IgG was not detected in the hemolymph of O. tholozani and A. persicus. There was no increase in the concentrations of host IgG in the hemolymph of the soft ticks during the first week following the blood meal. The potential contribution to the resistance of hosts against ticks by host antibodies that cross into the tick hemocoel is discussed.

Animals↗

Quantitative determination of free amino acids in the hemolymph of autogenous and anautogenous strains of Culex tarsalis (Diptera: Culicidae).

Autogenous and anautogenous strains were selected from the egg rafts of Culex tarsalis Coquillett collected from Coachella Valley, California. In autogenous (21-25 generations) and anautogenous (0-4 generations) strains used for hemolymph free amino acid analysis, the autogenous oviposition rates were 73.6-83.6% and 2.7-3.9%, the proportions of females undergoing autogenous ovarian development 120 h postemergence were 75.6 and 8.9%, respectively. To study the presence and quantities of free amino acids and explore their relationship to autogenous ovarian development, the 6 legs of females from both autogenous and anautogenous strains were removed at the coxo-femoral joints, and hemolymph was collected by centrifuging the bodies of 50-100 females. Proteins in the hemolymph were precipitated with 10% sulphosalicylic acid. On days 1, 4, 7, and 10 postemergence, a total of 17 free amino acids was found in females from the autogenous strain, and a total of 16 was found in females from the anautogenous strain in which asparagine (Asn) was absent. Comparisons of free amino acid concentrations between these 2 strains indicated that there were significant differences in total free amino acids and 13 individual free amino acids except Glu, Gln, Pro, and Met on day 1, total free amino acids and 14 individual free amino acids except Gln, Pro, and on day 4, and total free amino acids and 12 individual free amino acids except Asp, Glu, Gln, Pro, and Met on day 7 postemergence. There were no significant differences in the concentrations of individual and total free amino acids on day 10 postemergence. Female age affected free amino acid content in the autogenous strain, where total free amino acids and 14 individual free amino acid content in the autogenous strain, where total free amino acids and 14 individual free amino acids increased from day 1, peaked on day 4, declined on day 7, and declined further on day 10 postemergence. In the anautogenous strain, only total free amino acids and Ser, Gly, Ala, and Leu exhibited age-dependent changes in concentration, and the magnitude of changes in concentration was less than that in autogenous strain. Conclusively, autogenous ovarian development was the major reason for the changes in hemolymph free amino acid concentration postemergence. The current and previous findings indicate that the free amino acids, Arg, Gly, Ile, Leu, Lys, Phe, Ser, Thr, and Val putatively may be essential for vitellogenesis in mosquitoes.

Amino Acids↗

Control of bacterial infections in the hard tick Dermacentor variabilis (Acari: Ixodidae): evidence for the existence of antimicrobial proteins in tick hemolymph.

The ability of hard ticks to prevent infection by bacteria was investigated. During a 72-h period, virtually all Dermacentor variabilis females survived inoculation with Bacillus subtilis, Escherichia coli, and Staphyloccocus aureus but few survived infection with Pseudomonas aeruginosa. The hemocyte population increased to peak abundance at 48 h to approximately 6 times that of the uninfected controls. In contrast, the soluble hemolymph protein content decreased inversely as the hemocytes increased. D. variabilis hemolymph was found to be constitutively antimicrobial (i.e., hemolymph from bacteria-naive individuals inhibited bacterial growth). Infection with various bacterial species enhanced this innate capability. When hemolymph fractions separated by high-pressure liquid chromatography were tested for their ability to inhibit microbial growth, activity against the gram-positive bacterium, B. subtilis, was found in 2 polar fractions. Antimicrobial activity was lost when the fractions were incubated with protease. The least polar fraction contained 1 major protein, M(r) 14.5 kDa, that comigrated with human lysozyme. This protein, tentatively identified as tick lysozyme, was abundant in bacteria-naive ticks but increased greatly (43%) following challenge with B. subtilis. The identity of the other, more polar protein is unknown. Studies to characterize these antimicrobial proteins are planned.

Animals↗

The Fc fragment mediates the uptake of immunoglobulin C from the midgut to hemolymph in the ixodid tick Amblyomma americanum (Acari: Ixodidae).

The phenomenon of immunoglobulin uptake from the midgut into the hemolymph has been observed in both argasid and ixodid ticks, but the mechanism of the uptake is not known. Using capillary feeding of adult Amblyomma americanum (L.) female ticks, we investigated the role of immunoglobulin G Fc and Fab fragments in the uptake process. Intact IgG and fragments labeled with 125I were introduced alone or as a mixture with a 10-fold molar excess of unlabeled compounds into ticks, and then the concentration of the compounds after 3 and 6 h of continuous feeding was assessed in the hemolymph. Our results showed that the uptake of Fc fragments was approximately 4 times higher than Fab fragments at 6 h of the feeding and that Fc but not Fab fragments competed with uptake of intact IgG. Glycosylation of the immunoglobulins did not seem to be required for uptake. There was not a statistically significant difference between the uptake of untreated IgG and IgG treated either with periodate or N-glycanase, and untreated Fc fragments or deglycosylated Fc fragments had equal activity in competition experiments with IgG. The uptake into hemolymph of IgG and Fc fragments, but not Fab fragments, was dependent on the pH of the feeding solution and showed a maximum at approximately pH 7.0. In addition, tick midgut cells bound Fc fragments with high affinity, estimated at 21 nM; the interaction with Fab fragments seemed nonspecific. Our results suggest that Fc fragments are the major determinant for the specific uptake of immunoglobulin G into tick hemolymph.

Animals↗

Hemolymph transfer as an assay for immunorecognition in the cockroach Periplaneta americana and the locust Schistocerca gregaria.

A quantitative assay for measuring the number of hemocytic nodules formed in response to foreign particles and soluble molecules has been used, in the locust Schistocerca and the cockroach Periplaneta, to investigate the response to transferred hemolymph. Xenogeneic test particles, rabbit neutrophil leukocytes, stimulate formation of nodules when injected into both insect species, compared with saline-injected controls. However, the number of nodules formed in the locust in response to cockroach hemolymph is significantly reduced compared with the response to other xenogeneic cells, and it is suggested that, in view of the strong reactivity of cockroach hemocytes to locust hemolymph and plasma, a graft-versus-host response might be occurring in the recipient locust. Whole hemolymph transferred allogeneically between Periplaneta, or xenogeneically from Blatta to Periplaneta, does not stimulate a response in the recipient. This corresponds well with results from other assays for immunorecognition of transplants and is further confirmation that allogeneic and, in some combinations xenogeneic, recognition is absent in insects.

Animals↗

Specific hemagglutinin and a modulator of complement in cockroach hemolymph.

Natural hemagglutinin activity against vertebrate erythrocytes is present in the hemolymph of the cockroach Blabarus craniifer. The hemagglutinin titer against rabbit erythrocytes is high, whereas sheep and horse red cells agglutinate weakly. Hemagglutinin activity was depressed by the complement inhibitor, cobra venom factor. Cockroach hemagglutinin is heat-labile; all activity is destroyed by heating at 56 C for 1 hr. A humoral factor similar to the complement component 3 proactivator is also present in cockroach hemolymph. The formation of the cobra venom factor-hemolymph "complex" is dependent on the presence of divalent cations and will not proceed at 56 C. The hemolytic intermediate formed after treatment of cockroach hemolymph with cobra venom factor was active in the presence of serum treated with ethylenediaminetetraacetic acid to inactivate the early complement components.

Agglutinins↗

Changes in hemolymph glutathione status after variation in photoperiod and light-irradiance in crayfish Procambarus clarkii and Procambarus digueti.

This work studied the effect of light-stressors, irradiance and photoperiod length on the status of hemolymph glutathione in two species of crayfish, Procambarus clarkii and Procambarus digueti. Adult animals of each species were submitted to two experimental approaches: (1) two batches of each species were placed under low or high light irradiant conditions of light-dark (LD) 24 h cycles of two different photoperiod lengths, one normal LD 12: 12 and one extreme LD 20:4 low and high irradiance for 10 weeks. Time-dependent light changes on hemolymph glutathione concentration were determined throughout the entire experimental period; and (2) three batches of the two species were submitted to independent treatments consisting of the same LD 12:12 cycles of high and low irradiance and 20:4 high-irradiance LD cycles. Reduced and oxidized glutathione hemolymph concentrations were determined and total glutathione was calculated. In addition midgut glutathione reductase activity in both species was determined. The two species showed different hemolymph glutathione reactivity and glutathione status for the two light parameters. Dissimilar responses of both species, as well as the rate of mortality of P. digueti represent specific differences in the metabolic responses, as well as tolerance to photo-oxidative stress produced by light. The role of glutathione in the tolerance of crayfish to photo-oxidative stress is discussed.

Animals↗

[Changes in the activity and pattern of hemolymph esterases in the larvae of wax moth Galleria mellonella L. (Lepidoptera, Pyralidae) during mycosis].

The extended pattern of multiple esterase forms has been revealed in the hemolymph of wax moth Galleria mellonella larvae infected by the fungi Metarhizium anisopliae, Beauveria bassiana or Paecilomyces fumoso-roseus. The total esterase activity of the hemolymph also increases during mycosis. Mechanical damage of the cuticle, treatment with deltamethrin, and chilling of the caterpillars induced similar changes in the hemolymph pattern of esterase activity. Presumably, the changed spectrum and activity of the hemolymph esterases during mycosis is due to the damaged cuticle and epidermis cells.

Animals↗

The hemolymph of Chasmagnathus granulata Dana, 1851 (Decapoda-Grapsidae) as a target tissue of the crustacean hyperglycemic hormone.

The effect of crustacean hyperglycemic hormone (CHH) was investigated on the hemolymph of Chasmagnathus granulata, a meso-supralittoral crab from southern Brazil. Serum glucose increased significantly (P less than 0.05) after incubation of total hemolymph in the presence of the eyestalk extract of a member of the same species. Also, glucose uptake from blood serum, not affected by eyestalk extract (P greater than 0.05), was observed after incubation of total hemolymph in the presence of glucose. The results suggest that the hemolymph may be a target tissue of CHH and that this hormone may act by mobilizing carbohydrate reserves possibly from hematocytes.

Animals↗

Cloning and sequencing of a cDNA for the hemolymph juvenile hormone binding protein of larval Manduca sexta.

A cDNA for the hemolymph juvenile hormone binding protein (JHBP) of larval Manduca sexta has been cloned and sequenced. The JHBP was purified to homogeneity from fifth instar larval hemolymph using gel filtration chromatography, ion exchange chromatography, and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Polyclonal rabbit antibodies, generated in response to this protein, were used to identify and isolate JHBP cDNAs from a fat body expression library in bacteriophage lambda ZAPII. Eleven putative JHBP cDNA clones were isolated and subcloned into Bluescript plasmid; cDNA inserts were approximately 750 base pairs in length. A 36-kDa immunoreactive protein was expressed from these plasmids; this beta-galactosidase fusion protein, like the authentic 32-kDa JHBP, was specifically photoaffinity labeled with [3H] epoxyhomofarnesyl diazoacetate (EHDA). Single-stranded DNA from one clone was sequenced by the Sanger dideoxynucleotide method, using deletion and custom primer techniques. A mature translation product was identified which had 226 amino acid residues, a molecular mass of 25,111 daltons, and a predicted isoelectric point (pI) of 5.40. The cDNA correctly predicts the N-terminal amino acid sequence and the amino acid composition of an authentic M. sexta hemolymph JHBP. A computer search of protein and nucleic acid data bases failed to reveal any related sequences. Thus, M. sexta hemolymph JHBP appears to be the first member of a new superfamily of insect hormone binding proteins.

Affinity Labels↗

Lipid transfer particle in locust hemolymph: purification and characterization.

A lipid transfer particle (LTP) from the hemolymph of adult male locusts, Locusta migratoria, was isolated and purified. The locust LTP exhibited its capacity to catalyze the exchange of diacylglycerol between low density lipophorin (LDLp) and high density lipophorin (HDLp). Contrary to the LTP reported for the tobacco hornworm, M. sexta, the locust LTP appeared to lack the capacity to promote net transfer of diacylglycerol to form an intermediate density lipophorin, although it seems premature to conclude the complete lack of such a capacity in locust LTP. The original concentration of LTP in hemolymph is assumed to be extremely low compared to that of lipophorin; only a catalytic amount of LTP may be present in the hemolymph (e.g., only 160 micrograms of LTP was obtained from the original hemolymph containing 400 mg protein). The molecular weight of intact LTP was estimated to be about 600,000 and the LTP was comprised of three glycosylated apoproteins, apoLTP-I (mol wt 310K), apoLTP-II (mol wt 89K), and apoLTP-III (mol wt 68K). The locust LTP contained significant amounts of lipids; the total lipid content amounted to 14.4% and the lipids were comprised of 17% hydrocarbons, 44% diacylglycerol, 8% cholesterol, 13% free fatty acid, and 18% phospholipids. The above molecular properties of locust LTP are essentially similar to those reported for M. sexta LTP.

Animals↗

Preliminary observations on a hemolymph factor influencing the infectivity of Schistosoma mansoni miracidia.

It has been demonstrated that the infectivity of Schistosoma mansoni miracidia for a highly susceptible strain of Biomphalaria glabrata was reduced markedly when the miracidia were pretreated with hemolymph from the snail Helisoma caribaeum. Although the Helisoma hemolymph factor(s) responsible for this phenomenon has not been identified with certainty, it appears to be a snail lectin associated with binding sites for n-acetyl-D-glucosamine on the surface of the miracidium. Hemolymph from uninfected and infected B. glabrata and from a resistant strain of B. glabrata did not reduce the infectivity of miracidia, nor did pretreatment with bovine plasma albumin. Likewise, we demonstrated that reduction of miracidial infectivity was not due to the presence of a miracidial immobilizing factor found in the hemolymph of many snail species. Differences in the infectivity between pretreated miracidia and controls were statistically significant (P = 0.001).

Animals↗

Hemolymph of Anopheles stephensi from noninfected and Plasmodium berghei-infected mosquitoes. 1. Collection procedure and physical characteristics.

Hemolymph was collected from adult female Anopheles stephensi by centrifugation of incised mosquitoes. Approximately 0.1 muliter was collected from each recently emerged mosquito, although smaller amounts were recovered with increasing age of the mosquito. Determinations were made of the pH, osmotic pressure, and specific gravity of this hemolymph at various times during the life of the adult mosquito. The values obtained were within the ranges found for other insects. Hemolymph collected from mosquitoes fed on hamsters infected with Plasmodium berghei had different values than hemolymph from mosquitoes fed on noninfected hamsters. This probably was due to differences between the quality of these 2 types of blood meals, rather than to the direct effects of the malaria parasite on the infected mosquito itself.

Aging↗

Targets of octopamine action in the lobster: cyclic nucleotide changes and physiological effects in hemolymph, heart and exoskeletal muscle.

We have examined three potential targets of octopamine action of the lobster--hemolymph, heart and exoskeletal muscle--and found that each tissue responds to the amine with increases in cyclic adenosine 3': 5'-monophosphate (cAMP) and changes in measurable physiological phenomena. A highly specific octopamine-stimulated increase in cAMP is observed in hemolymph, and this effect is probably due to the presence of a unique octopamine receptor on hematocytes. Pharmacological studies show that synephrine is a potent agonist of the hemolymph receptor for octopamine and that the alpha adrenergic receptor blockers phentolamine and dibenamine and the dopamine receptor blocker, chlorpromazine, are antagonists. Addition of octopamine to lobster hemolymph increases the rate of changes the nature of the clotting reaction. AMP levels in lobster heart are elevated by both octopamine and serotonin. Both amines also increase the rate and the amplitude of the heart beat. Octopamine, serotonin and dopamine all increase cAMP levels in lobster exoskeletal muscle preparations, and each amine causes changes in muscle tension and the strength of nerve evoked contractions. In none of the tissues studied have we been able to establish a direct relationship between amine-stimulated increases in cAMP levels and the physiological responses.

Animals↗

Purification of lectin induced in the hemolymph of Sarcophaga peregrina larvae on injury.

A lectin was purified from the hemolymph of Sarcophaga peregrina larvae, obtained after injury of their body wall. This lectin agglutinated sheep red blood cells markedly and the hemagglutinating activity was inhibited by galactose and lactose. The active lectin was found to have a molecular weight of 190,000 and to consist of four alpha subunits and two beta subunits, with molecular weights of 32,000 and 30,000, respectively. During the early pupal stage, similar hemagglutinating activity in the hemolymph increased to several times than in larval hemolymph. This activity was completely inhibited by the antibody prepared against the lectin purified from the hemolymph of injured larvae. Thus, the same protein having lectin activity is apparently induced under two different physiological conditions: injury of the body wall of larvae and during pupation. The biological significance of this lectin is discussed.

Animals↗