Anthony Nappi

Loyola University Chicago | LUC · Department of Biology

Ascorbate (AH-) and certain other biological reductants have long been known to produce the cytotoxic hydroxyl radical (OH) when oxidized by hydrogen peroxide (H2O2) in the presence of copper or iron catalysts. The present study documents the in vitro production of the OH solely from the oxidation of AH- by H2O2, independent of mediation by transit...

Phagocytosis activity of hemocytes of the host Galleria mellonella (Lepidoptera) was modulated by the infection of the entomopathogenic nematode Steinernema feltiae (Rahbditida) and was found to be correlated with the opsonization of bacteria by hemolymph factors. The presence of nematodes resulted in a significative decrease in phagocytosis of bac...

The cellular innate immune response of several species of Drosophila terminates with the encasement of large foreign objects within melanotic capsules comprised of several layers of adhering blood cells or hemocytes. This reaction is manifested by various Drosophila hosts in response to infection by endoparasitic wasps (i.e., parasitoids). Creditab...

In larvae of Drosophila paramelanica, eggs and larvae of the endoparasitic wasp Leptopilina heterotoma succumb to an effective host reaction that does not involve blood cell–mediated melanotic encapsulation, a response that characterizes cellular immunity in various species of Drosophila and in many insects and other arthropods. A significant incre...

Insect host-parasitoid interactions involve complex physiological, biochemical and genetic interactions. Against endoparasitoids, immune competent hosts initiate a blood cell-mediated response that quickly destroys the intruders and envelops them in a multilayered melanotic capsule. During the past decade considerable progress has been made in iden...

Insect host-parasitoid interactions involve complex physiological, biochemical and genetic interactions. Against endoparasitoids, immune competent hosts initiate a blood cell-mediated response that quickly destroys the intruders and envelops them in a multilayered melanotic capsule. During the past decade considerable progress has been made in iden...

In insects, eukaryotic endoparasites encounter a series of innate immune effector responses mediated in large part by circulating blood cells (hemocytes) that rapidly form multilayer capsules around foreign organisms. Critical components of the encapsulation response are chemical and enzyme-catalyzed oxidations involving phenolic and catecholic sub...

The synthesis and involvement of H(2)O(2) during the early stages of melanogenesis involving the oxidations of DOPA and dopamine (diphenolase activity) were established by two sensitive and specific electrochemical detection systems. Catalase-treated reaction mixtures showed diminished rates of H(2)O(2) production during the autoxidation and tyrosi...

Insects transmit the causative agents for such debilitating diseases as malaria, lymphatic filariases, sleeping sickness, Chagas' disease, leishmaniasis, river blindness, Dengue, and yellow fever. The persistence of these diseases provides testimony to the genetic capacity of parasites to evolve strategies that ensure their successful development i...

The production and deposition of melanin pigments on invading pathogens and parasites represents a unique, innate immune response in the phylum Arthropoda. This immune response has started to receive considerable attention because of the potential to exploit this mechanism to control mosquito-borne diseases. In this article, we summarize knowledge...

Avirulent strains of the endoparasitoid Leptopilina boulardi succumb to a blood cell-mediated melanotic encapsulation response in host larvae of Drosophila melanogaster. Virulent wasp strains effectively abrogate the cellular response with substances introduced into the host that specifically target and effectively suppress one or more immune signa...

This review summarizes and compares available data on genetic and molecular aspects of resistance in four well-described invertebrate host-parasite systems: snail-schistosome, mosquito-malaria, mosquito-filarial worm, and Drosophila-wasp associations. It underlies that the major components of the immune reaction, such as hemocyte proliferation and/...

This review summarizes and compares available data on genetic and molecular aspects of resistance in four well-described invertebrate host-parasite systems: snail-schistosome, mosquito-malaria, mosquito-filarial worm, and Drosophila-wasp associations. It underlies that the major components of the immune reaction, such as hemocyte proliferation and/...

Immune-suppressive factors (ISFs) introduced into larvae of Drosophila melanogaster during infection by virulent endoparasitic wasps effectively block the innate immune response mediated by blood cells (hemocytes) but have little influence on the autoimmune response made by a tumor strain in which the blood cells manifest a similar response but ins...

Mosquito-borne diseases, including dengue, malaria, and lymphatic filariasis, exact a devastating toll on global health and economics, killing or debilitating millions every year (54). Mosquito innate immune responses are at the forefront of concerted research efforts aimed at defining potential target genes that could be manipulated to engineer pa...

Host larvae of Drosophila melanogaster injected with the eicosanoid biosynthesis inhibitor, dexamethasone, prior to parasitization by the wasp Leptopilina boulardi, exhibited significantly reduced rates of melanotic encapsulation in comparison with control and saline-injected larvae. The results of this investigation suggest that prostaglandins and...

Iron not only functions as a cofactor for various enzymes, but it is also a source of potentially cytotoxic molecules produced through interactions with certain reactive intermediates of oxygen (ROI) and nitrogen (RNI). Protection from such iron-mediated damage results in large part from homeostatic mechanisms that regulate the sequestration of iro...

Apoptosis is a form of cell death that is manifested in Parkinson's disease (PD) and certain other neurodegenerative disorders. Metabolites of salsolinol (SAL), an intraneuronal, dopamine-derived tetrahydroisoquinoline (TIQ), have been shown to induce apoptosis in human dopaminergic neuroblastoma cells, implicating these molecules as causative or c...

The effects of nitric oxide (NO) on both tyrosinase/O2- and horseradish peroxidase/H2O2-mediated oxidations of dopamine and its o-dihydric phenol precursor L-dopa were compared with autoxidative processes and quantitatively assessed by oxidative and reductive electrochemical detection systems. In peroxidase/H2O 2/NO-catalyzed reactions, significant...

Insects and other invertebrates lack the immunoglobulins and adaptive responses that characterize vertebrates yet possess efficient innate immune systems comprised of both cellular and humoral elements (Gillespie et al., 1997; Vilmos and Kurucz, 1998). The evolutionary origins and molecular basis for the various recognitive mechanisms remain among...

Host-parasite relationships represent integrating adaptations of considerable complexity involving the host's immune capacity to both recognize and destroy the parasite, and the latter's ability to successfully invade the host and to circumvent its immune response. Compatibility in Drosophila-parasitic wasp (parasitoid) associations has been shown...

The Drosophila-parasitic wasp (parasitoid) associations involve integrating adaptations of considerable complexity. This review focuses on some of the factors that influence these interactions including host immunity, nutrition and hormonal changes, and parasitoid virulence and mechanisms of immune suppression.

The main purpose of this study was to test the effect of instruction to improve the reasoning skills of undergraduates majoring in the field of education. The results of this investigation demonstrate the lack of proficiency in formal reasoning by undergraduate education majors in the areas of proportional, probabilistic, and correlational reasonin...

The augmented production of nitric oxide (NO) was observed during the hemocyte-mediated melanotic encapsulation responses of Drosophila melanogaster and D. teissieri. When introduced into the hemocoel of D. melanogaster larvae, NO activated the gene encoding the antimicrobial peptide Diptericin. These observations, together with previous studies do...

There is considerable evidence implicating iron and other redox-active transition metals as progenitors of reactive intermediates of oxygen (ROI), molecules which lead to oxidative stress and contribute to various neurodegenerative processes. An important aspect of such metal-mediated damage to biomolecules is the site-specific nature of such patho...

Although lacking the components that characterize the acquired immunity systems of vertebrates, invertebrates nevertheless possess effective general innate immune mechanisms which exhibit striking parallels with those of vertebrates. These innate immune systems include both cellular and humoral elements. Invertebrate phagocytes synthesize both oxyg...

Tetrahydroisoquinolines (TIQs) are intraneuronal, catecholamine-derived alkaloids that have been implicated in the etiology of Parkinson’s disease and in alcohol related disorders. The in vitro production of the cytotoxic hydroxyl radical (·OH) was recorded during the autoxidation of salsolinol (SAL) and salsolinol-1-carboxylic acid (SAL-1C), but n...

Tetrahydroisoquinolines (TIQs) are intraneuronal, catecholamine-derived alkaloids that have been implicated in the etiology of Parkinson's disease and in alcohol related disorders. The in vitro production of the cytotoxic hydroxyl radical (*OH) was recorded during the autoxidation of salsolinol (SAL) and salsolinol-1-carboxylic acid (SAL-1C), but n...

Upon infection with the wasp parasitoid Leptopilina boulardi, the blood cells or hemocytes of Drosophila melanogaster larvae become activated and manifest a type of communal phagocytosis wherein eggs of the parasitoid are enveloped by multicellular, melanotic capsules. Hemocytes engaged in this collaborative response generate reactive oxygen interm...

The differing effects of O-methylated catecholamines and their dihydroxyphenyl precursors on the production of *OH were quantified using a previously established specific salicylate hydroxylation assay in conjunction with a sensitive electrochemical detection system. The production of *OH by the Fenton reaction was diminished significantly by O-met...

The role of dietary yeast in Drosophila melanogaster cellular immunity was investigated. Host larvae deprived of yeast immediately after parasitization by the cynipid wasp Leptopilina boulardi encapsulated a significantly lower percentage of the parasitoid's eggs than hosts transferred to a medium with yeast. When the transfers of hosts were made 2...

The cellular immune response of Drosophila against metazoan parasites is characterized by the production of melanotic capsules comprised mostly of host blood cells (hemocytes). During the latter part of the ovipositional period of the cynipid wasp parasitoid Leptopilina boulardi, eggs are deposited into host larvae of Drosophila melanogaster that a...

The highly reactive and cytotoxic hydroxyl radical (OH) was found by electrochemical detection to be produced in reactions involving hydrogen peroxide (H2O2) and the nitric oxide (NO) donor diethylamine- NO complex. Using aromatic hydroxylation of salicylate as a specific indicator of OH, three salicylate hydroxylation products were identified; cat...

A sensitive electrochemical detection system was employed together with a specific salicylate hydroxylation assay to comparatively assess the effects of various substances on the iron-mediated generation of the hydroxyl radical (.OH). Hydroxyl radical production was found to be enhanced significantly by reduced glutathione, cysteine, ascorbic acid,...

Insect host-parasite interrelations involve co-adaptations of considerable complexity. Against endoparasites, immune competent insect hosts initiate a hemocyte-mediated response that quickly destroys the intruders and envelops them in multilayered, melanotic capsules. In this review, Yves Carton and Anthony Nappi focus on recent studies of the cyto...

The ability of iron chelates to promote hydroxyl radical (.OH) formation from hydrogen peroxide (H2O2) via Fenton chemistry was exploited to detect H2O2 produced during the oxidations of the eumelanin precursors 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). H2O2 generation during the autooxidations of DHI and DHICA wa...

Interest in 5-S-cysteinyldopa (5-S-CD), a major excretion product of normal and malignant melanocytes, has traditionally concentrated on its significance as a biosynthetic precursor of pheomelanins, the characteristic pigments of red hair, and as a specific biochemical marker for monitoring melanoma progression. The present study shows that 5-S-CD...

In an effort to identify serine proteases involved in the insect's immune response, we used a degenerate PCR approach to amplify putative serine protease gene fragments in Drosophila. Sequencing of the cloned PCR products identified one serine protease previously isolated in D. melanogaster (SER1/SER2), as well as two novel putative serine protease...

High pressure liquid chromatography with electrochemical detection (HPLC-ED) was employed in conjugation with a sensitive and specific salicylate hydroxylation assay to evaluate the immediate effects of hydroxyl radical (.OH) attack on four catechol intermediates of eumelanin, dopamine (3,4-dihydroxyphenylethylamine), its precursor dopa (3,4-dihydr...

Quinoid precursors of melanin and/or reactive oxygen species (ROS) generated during melanogenesis have been implicated as cytotoxic molecules in the immune responses of insects against their internal metazoan parasites. No study has yet identified the killing components produced in conjunction with melanotic encapsulation responses, or explained ho...

The interactions of ascorbic acid (AA) and reduced glutathione (GSH) in the oxidations of the catecholaminergic neurotoxins 6-hydroxydopa (TOPA) and 6-hydroxydopamine (6-OHDA) were investigated by both high performance liquid chromatography with electrochemical detection (HPLC-ED) and spectrometric methods. These comparative studies showed TOPA and...

The effects of glutathione, cysteine, and ascorbic acid on the monophenol and diphenol oxidase functions of tyrosinase were assessed by high performance liquid chromatography with electrochemical detection (HPLC-ED) at both oxidative and reductive potentials. The enzyme-catalyzed hydroxylations of tyrosine to dopa and tyramine to dopamine were inhi...

The activities of three enzymes, tyrosinase (monophenol oxidase, MPO), N-acetyltransferase (NAT), and tyrosine aminotransferase (TAT), were studied during eumelanotic encapsulation in host larvae of Drosophila melanogaster parasitized by the wasp, Leptopilina boulardi. At 24 h postinfection there was a tenfold increase in the MPO, whereas the activ...

Insects employ an arsenal of defences to successfully combat a diversity of nonself components. Their immune responses include phagocytosis, nodule formation, agglutination, secretion of antibacterial proteins, and cellular encapsulation (Ashida and Yamazaki, 1990; Boman et al, 1991; Christensen and Nappi, 1988; Coombe et al, 1984; Götz, 1986; Götz...

Until recently, investigations of the genetic aspects of the cellular immune reactions of insects and arthropods were scant (Götz and Boman, 1985; Stoffolano, 1986). One reason behind this paucity is that for most host-parasite interactions little or no information is available on the genetic systems of the interacting species. Also, it is extremel...

Larvae of Drosophila melanogaster produce a haemocytic reaction against eggs of the parasitoid Leptopilina boulardi, which leads to the formation of a multicellular capsule surrounding the foreign object. Melanization resulting from the conversion of phenol to o-quinones frequently accompanies the cellular reaction. Although various cytological and...

1. The melanotic encapsulation response made by larvae of a temperature-sensitive dopa decarboxylase (DDC) mutant strain of Drosophila against the parasitic wasp Leptopilina was severely compromised in hosts with reduced levels of DDC. 2. Dopa and 5,6-dihydroxyindole (DHI) were two hemolymph components identified in hosts exhibiting a melanotic enc...

3,4-Dihydroxyphenylalanine, 5-6-dihydroxyindole, and N-acetylarterenone were detected by electrochemical methods in the hemolymph of immune reactive larvae of Drosophila melanogaster following parasitization by the wasp Leptopilina boulardi. Determinations of the catechols were made after separation by reverse phase, ion-pairing high pressure liqui...

A principal reaction in the eumelanin biosynthetic pathway is the conversion of dopachrome (DC) to dihydroxyindole(s). Dopachrome isomerase (DI), the enzyme that catalyzes this reaction, was detected for the first time in larvae of D. melanogaster. Unlike the enzyme from B16 mouse melanoma cells which converts dopachrome to 5,6-dihydroxyindole-2-ca...

The early enzyme-mediated reaction sequence in the biosynthesis of melanin from L-tyrosine involves an initial hydroxylation (monophenol oxidase activity, MPO) of the aromatic amino acid precursor to form L-dopa (3,4-dihydroxyphenylalanine), and the ensuing oxidation (diphenol oxidase activity, DPO) of the resultant diphenol to form dopaquinone. By...

A very sensitive, specific and reliable quantitative assay was developed for measuring the rate of hydroxylation of tyrosine by mushroom tyrosinase using high pressure liquid chromatography with electrochemical detection (HPLC-ED). The assay employs N-acetyldopamine (NADA) as cofactor and ascorbate as a reducing agent. The product of the reaction,...

Larval hemolymph tyrosinase activity in Drosophila melanogaster was detected with high performance liquid chromatography with electrochemical detection. The enzyme hydroxylated L-tyrosine, and oxidized the diphenol substrates L-dopa and dopamine. In larvae of a selected immune-reactive strain the rates of tyrosine hydroxylation, dopa oxidation, and...

A hemocyte-mediated melanotic encapsulation reaction is elicited in adult Aedes aegypti in response to intrathoracically inoculated microfilariae of Dirofilaria immitis. The activity of monophenol oxidase in cell-free hemolymph collected from uninoculated, microfilariae-inoculated and saline-inoculated control mosquitoes was investigated using a qu...

This study involved the assessment of surface changes on hemocytes of Aedes aegypti black-eyed Liverpool strain in association with the melanization response against intrathoracically inoculated Dirofilaria immitis microfilariae (mff). Surface changes on hemocytes were identified using fluorescein-labeled wheat germ agglutinin (WGA). In mosquitoes...

Despite the absence of immunoglobulin-like recognition molecules, the immune reactive blood cells (hemocytes) of invertebrates are capable of responding with a high degree of specificity against a diversity of nonself components. Foreign objects too large to be phagocytosed are sequestered by numerous blood cells that adhere to one another and to t...

Failure of the nematode H. autumnalis to develop in M. domestica is attributed to the defense reaction of host larvae to the infective, gamogenetic stage of the parasite. The defense reaction involves melanization and encapsulation of the parasite, and is manifested as changes in the hemocyte picture of the host.Differential hemocyte counts suggest...

The hemocytes of Drosophila euronotus Patterson & Ward larvae were studied with phase-contrast microscopy and in films stained with Giemsa. Five types of hemocytes were described: prohemocytes, plasmatocytes, podocytes, lamellocytes, and oenocytoids. Differential counts of hemocytes during development showed that the plasmatocytes were the most num...