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Comparative study of hemolymph phenoloxidase activity in Aedes aegypti and Anopheles quadrimaculatus and its role in encapsulation of Brugia malayi microfilariae.

Hemolymph phenoloxidase activity of sugar-fed and blood-fed females of Anopheles quadrimaculatus and Aedes aegypti showed similar characteristics. Phenoloxidase was present as an inactive proenzyme in both mosquito species and was partially activated during collection of the hemolymph. In both mosquito species, phenoloxidase activity was modulated by different buffers and activated phenoloxidase did not need Ca2+. Enzymatic activity was higher in the hemocytes than in the plasma in both mosquito species. Trypsin, laminarin, and blood-feeding on uninfected and Brugia malayi-infected jirds enhanced hemolymph phenoloxidase activity in both mosquito species. The appearance of hemolymph phenoloxidase activity was inhibited by p-nitrophenyl p'-guanidinobenzoate HCl, soybean trypsin inhibitor, ethylenediaminetetraacetic acid, diethyldithiocarbamic acid, saturated 1-phenyl-2-thiourea and reduced glutathione, but not by benzamidine in A. quadrimaculatus. The appearance of hemolymph phenoloxidase activity was inhibited by benzamidine, diethyldithiocarbamic acid, saturated 1-phenyl-2-thiourea, reduced glutathione, p-nitrophenyl p'-guanidinobenzoate and soybean trypsin inhibitor, but not by ethylenediamine-tetraacetic acid in A. aegypti. It is suggested that in both mosquito species, blood-feeding and migration of sheathed microfilariae in the homocoel activated the prophenoloxidase in the hemolymph and caused the encapsulation and melanization of microfilarial sheaths and microfilariae of B. malayi.

Animals↗

The Toll immune-regulated Drosophila protein Fondue is involved in hemolymph clotting and puparium formation.

Clotting is critical in limiting hemolymph loss and initiating wound healing in insects as in vertebrates. It is also an important immune defense, quickly forming a secondary barrier to infection, immobilizing bacteria and thereby promoting their killing. However, hemolymph clotting is one of the least understood immune responses in insects. Here, we characterize fondue (fon; CG15825), an immune-responsive gene of Drosophila melanogaster that encodes an abundant hemolymph protein containing multiple repeat blocks. After knockdown of fon by RNAi, bead aggregation activity of larval hemolymph is strongly reduced, and wound closure is affected. fon is thus the second Drosophila gene after hemolectin (hml), for which a knockdown causes a clotting phenotype. In contrast to hml-RNAi larvae, clot fibers are still observed in samples from fon-RNAi larvae. However, clot fibers from fon-RNAi larvae are more ductile and longer than in wt hemolymph samples, indicating that Fondue might be involved in cross-linking of fiber proteins. In addition, fon-RNAi larvae exhibit melanotic tumors and constitutive expression of the antifungal peptide gene Drosomycin (Drs), while fon-RNAi pupae display an aberrant pupal phenotype. Altogether, our studies indicate that Fondue is a major hemolymph protein required for efficient clotting in Drosophila.

Animals↗

Joint action of elevated ambient nitrite and nitrate on hemolymph nitrogenous compounds and nitrogen excretion of tiger shrimp Penaeus monodon.

Penaeus monodon (12.13+/-1.14 g) exposed individually to six different nitrite and nitrate regimes (0.002, 0.36 and 1.46 mM nitrite combined with 0.005 and 7.32 mM nitrate), at a salinity of 25 ppt, were examined for hemolymph nitrogenous compounds and whole shrimp's nitrogen excretions after 24 h. Nitrogen excretion increased directly with ambient nitrite and nitrate. Hemolymph nitrite, nitrate, urea and uric acid levels increased, while hemolymph ammonia, oxyhemocyanin and protein were inversely related to ambient nitrite. Exposure of P. monodon to elevated nitrite in the presence of 7.32 mM nitrate did not alter hemolymph nitrite, ammonia, uric acid, oxyhemocyanin and protein levels, but caused an increase in hemolymph nitrate and a decrease in hemolymph urea as compared to exposure to elevated nitrite only. Following exposure to elevated nitrite, nitrite was oxidized to nitrate and P. monodon showed uricogenesis and uricolysis. The shrimp also used strategies to avoid joint toxicities of nitrite and metabolic ammonia by removing ammonia or reducing ammonia production under the stress of elevated nitrite.

Ammonia↗

Male sex pheromonal components derived from methyl eugenol in the hemolymph of the fruit fly Bactrocera papayae.

Pharmacophagy of methyl eugenol (ME)--a highly potent male attractant, by Bactrocera papayae results in the hydroxylation of ME to sex pheromonal components, 2-ally-4,5-dimethoxyphenol (DMP) and (E)-coniferyl alcohol (CF). These compounds, which are also male attractants, are then sequestered and stored in the rectal gland prior to their release during courtship at dusk. Chemical analyses of the digestive tract (excluding the crop and rectal gland) showed the absence of the sex pheromonal components and their precursor, ME. However, B. papayae males were attracted to and fed on the ME-fed male hemolymph extracts but not on hemolymph extracts of ME-deprived males. After thin layer chromatography in a hexane:ethyl acetate solvent system, flies were attracted to and fed on the original point on the TLC plate where the hemolymph extract had been spotted, suggesting that the pheromone components were bound in polar complexes. Chemical analyses of the ME-fed male hemolymph and crop extracts revealed the presence of the sex pheromonal components. The presence of the ME-derived pheromonal components and the absence of ME in the hemolymph suggest that the hemolymph is involved in the transportation of sex pheromonal components from the crop to the rectal gland.

Animals↗

Enhancement of OspC expression by Borrelia burgdorferi in the presence of tick hemolymph.

Borrelia burgdorferi B31 cultured at 28 degrees C was used to assay the effects of tick hemolymph on outer surface protein C (OspC) surface expression. Using immunofluorescence, OspC surface expression was shown to increase in cultures treated with hemolymph from both Ixodes scapularis and Dermacentor variabilis, while control samples (non-hemolymph treated) showed no increase in the levels of OspC. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis also showed an increase in OspC from spirochetes exposed to tick hemolymph. In addition, a lower-molecular-mass protein band of unknown identity was also enhanced in the hemolymph-exposed spirochetes. The significance of these effects of tick hemolymph on B. burgdorferi outer surface protein expression is unknown.

Animals↗

Cations in hemolymph and alimentary tract tissues of healthy and milky diseased European chafer (Amphimallon majalis) larvae.

A study was made of certain cations present in hemolymph and alimentary tract tissues of healthy and diseased European chafer larvae and the spores of Bacillus popilliae collected from diseased hemolymph. The major ions found in the hemolymph, in order of decreasing abundance, were potassium, magnesium, sodium, and calcium. Hemolymph of diseased larvae contained relatively higher concentrations of sodium, potassium, magnesium, iron, and zinc than hemolymph of healthy larvae. Concomitantly, the concentrations of ions were lower in the mid-gut and anterior intestinal tissues of diseased larvae. Only sodium decreased slightly in the diseased tissues of the rectum and rectal sac; other ions remained unchanged or increased. Little or no manganese or copper was detected in the hemolymph or tissues. The major cations of spores of B. popilliae were sodium, calcium, and magnesium. Small amounts of potassium, manganese, copper, iron, and zinc were detected in the spores. Based on calcium and dipicolinic acid determinations of the spores, sufficient calcium was found to allow for the formation of calcium dipicolinate in the expected concentrations.

Animals↗

Bacterial flora of the hemolymph of the blue crab, Callinectes sapidus: most probable numbers.

The hemolymph of 290 freshly collected blue crabs from Chincoteague Bay, Va., was sampled over a 15-month period from August 1968 through November 1969 and most probable numbers of bacteria were determined by tube dilution. The hemolymph of 18% of all crabs sampled was found to be sterile, with 16% sterility in summer and 23% in winter samples. Despite individual variations, male crabs as a group had a higher bacterial hemolymph burden than females, and among both sexes summer counts were higher than winter. The hemolymph of crabs with missing appendages had significantly higher counts than uninjuried crabs. The annual mean hemolymph most probable numbers per ml was 2,756 for males, 1,300 for females, and 1,876 for both sexes. The higher bacterial levels found in the hemolymph of male crabs may, in part, be explained by the fact that males, which predominated in the summer samples, had a higher incidence of injury and missing appendages than did females.

Animals↗

Superoxide anion in Anopheles albimanus hemolymph and midgut is toxic to Plasmodium berghei ookinetes.

The mechanisms of Plasmodium spp. elimination in resistant mosquitoes are not completely understood. Some resistant anopheline strains are able to melanize Plasmodium spp. ookinetes in their midguts. Because quinoid compounds are potent catalysts for free radical generation and because these radicals can be generated in association with melanogenesis, it is probable that they play an important role in the elimination of parasites. The production of the superoxide anion (O-2) in the hemolymph and midgut of Anopheles albimanus female mosquitoes and its cytotoxic effect on Plasmodium berghei ookinetes were analyzed. Ookinetes inoculated into the hemocoel of A. albimanus were covered with melanin and then encapsulated by hemocytes within 1 hr. The presence of O-2 in midguts and in hemolymph obtained by perfusion was verified by the reduction of 3-(4,5 dimethylthiazolil-2)-2,5-diphenyl tetrazolium bromide. O-2 was generated in the hemolymph obtained by perfusion and midguts only in the presence of dihydroxyphenylalanine (L-DOPA), and this reaction was inhibited by superoxide dismutase (SOD). Plasmodium berghei ookinetes exposed to hemolymph plus L-DOPA were killed in vitro, but addition of SOD prevented their killing. Prophenoloxidase transcripts were not observed in midgut epithelium, suggesting that toxic compounds may be imported from the hemolymph. These results suggest that A. albimanus hemolymph and midguts produce O-2 that may limit Plasmodium spp. parasite development.

Animals↗

Lipoprotein interconversions in an insect, Manduca sexta. Evidence for a lipid transfer factor in the hemolymph.

Hemolymph lipoproteins (lipophorins) of adult Manduca sexta are disinct from larval forms in density, lipid content, composition, and the presence of a third, low molecular weight apoprotein. Generally, only one lipoprotein species exists in M. sexta hemolymph during any given life stage. Progression through the life cycle results in alterations of existing lipoproteins to produce new forms, without new protein synthesis. The observed alterations in lipoprotein density could result from facilitated lipid transfer in insect hemolymph. An in vitro assay of facilitated lipid transfer was developed which employs a high density lipophorin from the wandering larva (density = 1.18 g/ml) as acceptor and adult low density lipophorin (density = 1.03 g/ml) as donor. Adult lipophorin-deficient hemolymph was shown to catalyze a time-dependent equilibration of the starting lipoproteins to produce a new intermediate lipophorin, Lp-I. Hydrodynamic experiments on the donor, acceptor, and product lipoproteins excluded fusion as the mechanism whereby Lp-I is produced. Thus, it is concluded that Lp-I results from facilitated net lipid transfer from low to high density lipoprotein. Furthermore, experiments conducted with radioiodinated donor and radioiodinated acceptor lipoproteins demonstrated that apoprotein exchange does not occur during the lipid transfer reaction. When donor lipoprotein was labeled in the lipid moiety with carbon-14, evidence of diacylglycerol and phospholipid exchange was obtained. Partial characterization of the lipid transfer factor revealed a relationship between incubation time, donor concentration, acceptor concentration, lipophorin-deficient hemolymph concentration, and transfer activity, as measured by Lp-I production. It is concluded that lipophorin-deficient hemolymph contains one or more factor(s) that catalyze net lipid transfer as well as diacylglycerol and phospholipid exchange between lipophorins to produce a single form at equilibrium.

Animals↗

Demonstration of Anaplasma marginale in hemolymph of Dermacentor andersoni by animal inoculation and by fluorescent-antibody technique.

Hemolymph was collected from adult Dermacentor andersoni Stiles that had been infected with Anaplasma marginale Theiler as nymphs. Before hemolymph was collected, the adult ticks were either incubated and unfed at 37 C for 2.5 days or fed for 6 days on sheep. Hemolymph collected from groups of 100 ticks was inoculated into susceptible splenectomized calves. Smears of hemolymph from the same groups of ticks were prepared for examination by fluorescent antibody technique. Hemolymph from incubated ticks caused anaplasmosis in 2 of 4 trials, and hemolymph from feeding ticks caused anaplasmosis in 4 of 4 trials. Moderately fluorescing bodies were demonstrated in some hemocytes from incubated ticks, whereas hemocytes from feeding ticks contained numerous clusters of brightly fluorescing bodies. Fluorescing bodies were not observed in hemocytes from control ticks.

Anaplasma↗

Selective transport of the mulberry leaf urease from the midgut into the larval hemolymph of the silkworm, Bombyx mori.

Just before spinning, larvae of the silkworm, Bombyx mori, absorb intact urease of the host plant (mulberry leaf) from the midgut lumen into the hemolymph. In order to investigate whether the transport of the mulberry leaf urease is selective, crude proteins extracted from the mulberry leaves were labeled with biotin and orally administered to the fifth instar larvae. The biotinylated proteins transported into the hemolymph were detected by ligand blotting using streptavidin. When the biotinylated proteins were administered to 5-day-old fifth instar larvae, a strong signal of a biotinylated protein was detected in the hemolymph 2 days after the administration. In contrast, when the biotinylated mulberry leaf proteins were administered to 3-day-old fifth instar larvae, no signal derived from the biotinylated proteins was detected in the hemolymph. The signal weakened when the biotinylated proteins had been immunoprecipitated before administering to the larvae, indicating that the signal came from the mulberry leaf urease. These results show that the transport of the mulberry leaf urease from the midgut into the hemolymph is selective and larval-stage specific. Subsequently, binding assays were carried out to test the binding ability of the mulberry leaf urease to the brush border membrane in the epithelial cells of larval midgut. The urease was not bound to the brush border membrane vesicles (BBMV) from the midgut of 3-day-old fifth instar larvae, while more than 60% of the total amount of incubated urease was bound to the BBMV from the midgut of 6-day-old fifth instar larvae. The urease binding ability of BBMV correlated with the uptake of the mulberry leaf urease. This suggests that a urease binding molecule(s) exists in the BBM of the midgut epithelium, which is involved in the uptake of the mulberry leaf urease. In addition, the uptake of the mulberry leaf urease into the hemolymph was induced by 20-hydroxyecdysone.

Journal Article↗

Development changes in juvenile hormone and juvenile hormone acid titers in the hemolymph and in-vitro juvenile hormone synthesis by corpora allata of the silkworm, Bombyx mori.

A simple method was developed to quantify hemolymph juvenile hormone (JH) and JH acid in hemolymph extracts from Bombyx mori with an established radioimmunoassay (RIA) for JH I. When various organic solvent extracts of hemolymph were assayed by RIA, levels of non-specific binding of the labeled ligand in the assay were determined to be greater than 50% of the maximum amount of the label bound by the antiserum. When hemolymph was diluted with methanol:water:8.4N ammonium hydroxide (10:9:1) and extracted with isooctane, non-specific binding was only 50% higher than control levels obtained with the assay buffer alone. The organic phase contained only JH and aqueous phase, JH acid. Consequently, this extraction method was used to prepare samples for RIA and enabled the separate measurement of JH and JH acid in hemolymph. With this method, changes in the hemolymph titers of JH and JH acid were determined from the third instar through early pupal stage of Bombyx mori. Changes in the in vitro secretory activity of corpora allata and brain-corpora cardiaca-corpora allata complexes from fifth instar larvae were also determined by using JH I RIA of the incubation medium.

Journal Article↗

Involvement of adipokinetic hormone in the homeostatic control of hemolymph trehalose concentration in the larvae of Bombyx mori.

Prior to wandering, 5th instar larvae of the silkworm, Bombyx mori, maintain constant hemolymph titers of trehalose. Head ligation of day 3, 5th instar larvae significantly decreased the hemolymph trehalose concentrations, but the concentrations did not decrease in starved larvae. After being diluted by replacement of larval hemolymph with insect Ringer's solution, the trehalose concentrations recovered the initial levels in 90 min in the non-ligated larvae, while they were not restored in 90 min in the neck-ligated larvae. These results suggest that a head factor(s) with hypertrehalosemic activity is involved in the homeostatic control of hemolymph trehalose concentration. When adipokinetic hormone (AKH) was injected into neck-ligated larvae, the trehalose concentrations increased in 2 h and decreased thereafter. Repeated injections of AKH every 4 h maintained the concentrations for 12 h. These findings suggest that AKH induces a hypertrehalosemic response and is involved in the homeostasis of hemolymph trehalose concentration in the larval feeding period.

Animals↗

Purification and characterization of biliverdin-binding vitellogenin from the hemolymph of the common cutworm, Spodoptera litura.

Biliverdin-binding vitellogenin (Vg) was purified from adult female hemolymph of the common cutworm, Spodoptera litura, by using gel filtration and ion exchange chromatographies. The molecular mass of the protein was 490 kDa and it was composed of two 188-kDa subunits. Three internal amino acid sequences obtained by digestion of the protein with lysylendopeptidase showed high similarity to those of Bombyx mori Vg, supporting the purified blue protein to be vitellogenin. latroscan analyses demonstrated the presence of biliverdin in Vg that occupied 2.4% of total lipid components. Among the lipids of Vg (9.5 micrograms total lipids per 100 micrograms protein), diacylglycerol was the most predominant, followed by phospholipid, hydrocarbons, and then triacylglycerol, while in biliverdin-binding proteins (BPs) purified from larval hemolymph (3.1 micrograms total lipids per 100 micrograms protein), phospholipid was the most abundant lipid followed by diacylglycerol; hydrocarbons and triacylglycerol were minor components. Vg was first detected in the hemolymph of female pupae one day before eclosion, but injection of 5 micrograms of methoprene into a 3-day-old pupa induced Vg in the hemolymph 4 days earlier than in the control. Methoprene also induced a faster decline in BP-A and BP-B titers in the hemolymph with a corresponding increase of the Vg titer. These results suggest that juvenile hormone (JH) induces not only vitellogenesis but also the uptake of these proteins by stimulating the metamorphosis of fat body during the pupal stage.

Amino Acid Sequence↗

Effects of dietary or injected organic cations on larval Drosophila melanogaster: mortality and elimination of tetraethylammonium from the hemolymph.

This study of larval Drosophila melanogaster examined the effects of injecting the prototypical organic cation tetraethylammonium (TEA) into the hemocoel or adding TEA and/or other organic cations to the diet. Mortality, hemolymph TEA levels, and Malpighian tubule TEA secretion rates were measured. The LD50 for dietary TEA was 158.4 mM and mortality increased if competitive inhibitors of organic cation transporters were also included in the diet. Mortality increased from 24% on TEA (100 mM) alone to 83 and 67% when the diet contained both TEA and quinidine (10 mM) or cimetidine (100 mM), respectively. TEA-selective microelectrode measurements indicated that hemolymph TEA concentration was approximately 3% of that in the diet for larvae maintained on TEA-enriched diet for 24 h. Malpighian tubules isolated from larvae exposed to dietary TEA excreted more TEA than did tubules from controls fed a TEA-free diet. However, the rate of decline of hemolymph TEA concentration following ingestion or injection of TEA into the hemocoel was greater than that explicable by rates of active transport by the gut and Malpighian tubules (MTs). We propose that TEA concentrations in the hemolymph are reduced not only by active transport across the MTs and gut, but also by diffusion into the gut. The latter pathway is particularly important when larvae previously maintained upon TEA-enriched diet are transferred to a TEA-free diet. The ingestion of TEA-free food not only clears the gut lumen, but also creates a TEA-free compartment into which TEA may passively diffuse from the hemolymph.

Animals↗

Effects of female wasp accessory secretions, host fat body, and host hemolymph on protein synthesis and egg viability in Microplitis croceipes (Braconidae).

Effects of female wasp reproductive gland secretions, host fat body and hemolymph, and mechanical constriction of the parasitoid egg on protein synthesis were studied in eggs of Microplitis croceipes (Braconidae) dissected from the wasp ovary. Protein synthesis was measured by 35S-methionine incorporation in eggs held in tissue culture medium for 16 h after treatment. Synthesis was stimulated in oocytes obtained from three regions of the ovary (egg tube, reservoir, and calyx) by fat body and venom gland but not by calyx fluid. A combination of fat body, venom gland, and calyx fluid did not enhance the level of synthesis relative to that of fat body or venom gland alone. Host hemolymph inhibited protein synthesis when incubated directly with the dissected eggs but not when the eggs were collected from an artificial oviposition substrate (AOS) containing hemolymph. The inhibitory effect of the hemolymph is thought to be due to the occurrence of melanization. Mechanical constriction did not alter the rate of synthesis, confirming an earlier report that synthesis in newly deposited eggs in ongoing and is not dependent on mechanical activation during the act of oviposition. Mechanisms responsible for sustaining protein synthesis in eggs for 16 h in vitro after their exposure to host hemolymph in the AOSs or fat body and venom gland are not known. Only a small percentage (less than 2%) of dissected ovarial reservoir oocytes that were mechanically constricted and exposed to the venom gland, calyx fluid, and host fat body hatched in vitro. In contrast, an earlier study demonstrated that 38% of eggs oviposited by female wasps into AOSs developed and hatched.

Animals↗

Isolation and characterization of bacteria-induced protein P4 from hemolymph of Manduca sexta.

Insects synthesize several types of hemolymph proteins in response to bacterial infection. The objective of this study was to characterize a 48,000 dalton hemolymph protein induced in larvae of Manduca sexta after injection of bacteria. The protein, isolated by cation exchange and gel filtration chromatography from hemolymph of larvae injected with Micrococcus lysodeikticus, was found to be a glycoprotein with pI = 8.4. The molecular weight, isoelectric point, amino acid composition, and NH2 terminal sequence of the protein are similar to bacteria-induced protein P4 from Hyalophora cecropia, and the M. sexta protein is also designated P4. The hemolymph concentration of M. sexta P4 (35 +/- 7 micrograms/ml in day 3 fifth instar larvae) increases 30- to 45-fold by 48 h after injection of bacteria, but it does not increase in response to injection of distilled water. Lower levels of induction occur after injection of peptidoglycan fragments, zymosan, and lipopolysaccharide. The properties of M. sexta P4 are very similar to those of a previously characterized M. sexta hemolymph protein known as postlarval protein, and antibodies against P4 bind to post-larval protein.

Amino Acids↗

Selectivity in storage hexamerin clearing demonstrated with hemolymph transfusions between Hyalophora cecropia and Actias luna.

When Hyalophora cecropia hemolymph was injected into wandering Actias luna larvae, a methionine-rich hexamerin was selectively transferred to the host's fat body, and completely cleared from the hemolymph by the time of pupal eclosion. Donor arylphorin was 30-40% removed from the hemolymph, and riboflavin-binding hexamerin was even less completely cleared. During the pupal-adult molt, these rates were reversed: methionine-rich hexamerin disappeared no faster than bovine serum albumin, while riboflavin-binding hexamerin was rapidly and completely cleared from the hemolymph, even though A. luna hemolymph lacks a homologue of this protein; arylphorin, again, was cleared at an intermediate rate. Selective clearing of the three hexamerins occurred at similar stages in H. cecropia, their species of origin. Developmentally programmed clearing, with selectivity at least partially conserved between genera, was also demonstrated with transfused vitellogenin: in A. luna females that were forming yolk, H. cecropia vitellogenin was cleared more rapidly than bovine serum albumin; but in younger females, and in males at all stages of metamorphosis, this Mr 510,000 molecule was instead an indicator of nonselective, large protein clearing. Nonselective clearing was more complete during adult development than during pupation. It also showed signs of being more effective for small than for large proteins, insensitive to carbohydrate conjugates, and unsaturated at the protein levels used.

Animals↗