PAP1 activates the prophenoloxidase system against bacterial infection in Musca domestica

We previously identified three putative prophenoloxidase-activating proteinase (mdPAP1, mdPAP2, and mdPAP3) genes from housefly Musca domestica by transcriptomic analysis. In this study, mdPAP1 cDNA was cloned, and the function of its encoded protein was analyzed. The cDNA of mdPAP1 was 1358 bp, and it contained a single open reading frame of 1122 bp encoding a predicted MdPAP1 protein of 373 amino acids. The estimated molecular weight of MdPAP1 was 41267.08 Da with an isoelectric point of 6.25. The deduced amino acid sequence of MdPAP1 exhibited high similarity to known PAPs of insects. mdPAP1 was detected in larvae, pupae, and adult housefly, and the expression level of mdPAP1 was upregulated in bacterial challenged larvae. The recombinant protein of MdPAP1 expressed in Escherichia coli could cleave the prophenoloxidase into phenoloxidase in M. domestica hemolymph infected by bacteria and result in a significant increase of the total phenoloxidase activity. In addition, RNA interference-mediated gene silencing of mdPAP1 significantly increased the mortality of M. domestica larvae. Results indicated that mdPAP1 was involved in the activation of the prophenoloxidase against bacterial infection in M. domestica.

Identifying and Characterizing a Novel Peritrophic Matrix Protein (MdPM-17) Associated With Antibacterial Response From the Housefly, Musca domestica (Diptera: Muscidae)

Peritrophic matrix/membrane (PM) critically prevents the midgut of insects from external invasion by microbes. The proteins in the peritrophic membrane are its major structural components. Additionally, they determine the formation and function of this membrane. However, the role of PM proteins in immune regulation is unclear. Herein, we isolated a novel PM protein (MdPM-17) from Musca domestica larvae. Further, the function of MdPM-17 in regulating host innate immunity was identified. Results showed that the cDNA of MdPM-17 full is 635 bp in length. Moreover, it consists of a 477-bp open reading frame encoding 158 amino acid residues. These amino acid residues are composed of two Chitin-binding type-2 domain (ChtBD2) and 19 amino acids as a signal peptide. Moreover, tissue distribution analysis indicates that MdPM-17 was enriched expressed in midgut, and moderate levels in the fat body, foregut, and malpighian tubule. Notably, MdPM-17 recombinant protein showed high chitin-binding capacity, thus belongs to the Class III PM protein group. MdPM-17 protein silencing via RNA interference resulted in the expression of antimicrobial peptide (defensin, cecropins, and diptericin) genes, and this occurred after oral inoculation with exogenous microbes Escherichia coli (Enterobacteriales:Enterobacteriaceae), Staphylococcus aureus (Bacillales:Staphylococcaceae), and Candida albicans (Endomycetales:Saccharomycetaceae)). Therefore, all the antimicrobial peptide (AMP) gene expression levels are high in MdPM-17-depleted larvae during microbial infection compared to controls. Consequently, these findings indicate that MdPM-17 protein is associated with the antibacterial response from the housefly.

Two ferritin genes (MdFerH and MdFerL) are involved in iron homeostasis, antioxidation and immune defense in housefly Musca domestica

Ferritin is a ubiquitous multi-subunit iron storage protein, made up of heavy chain and light chain subunits. In recent years, invertebrate ferritins have emerged as an important, yet largely underappreciated, component of host defense and antioxidant system. Here, two alternatively spliced transcripts encoding for a unique ferritin heavy chain homolog (MdFerH), and a transcript encoding for a light chain homolog (MdFerL) are cloned and characterized from Musca domestica. Comparing with MdFerH1, a fragment is absent at the 5' untranslated region of MdFerH2, where a putative iron response element is present. Amino acid sequence analysis shows that MdFerH possesses a strictly conserved ferroxidase site, while MdFerL has a putative atypical active center. Tissue distribution analysis indicates that MdFers are enriched expressed in gut. When the larvae receive diverse stimulations, including challenge by bacteria, exposure to excess Fe²⁺, doxorubicin or ultraviolet, the expression of MdFers is positively up-regulated in different degrees and different temporal patterns, indicating their potential roles in oxidative stress. The two mRNA isoforms of MdFerH appear to be differentially expressed in different tissues, but seem to show the similar expression patterns under diverse stress conditions. Further investigation reveals that silencing MdFers can alter the redox homeostasis, leading elevated mortalities of larvae following bacterial infection. Inspiringly, recombinant MdFerL produced in Pichia pastoris shows significant iron-chelating activity in vitro. These results suggest a pivotal role of ferritins from housefly in iron homeostasis, antibacterial immunity and redox balance.

Involvement of trehalose-6-phosphate synthase in innate immunity of Musca domestica

Trehalose-6-phosphate synthase (TPS) is responsible for synthesizing trehalose, which is prevalent in crustaceans and insects as blood-sugar. In this paper, a TPS gene from Musca domestica(MdTPS)has been cloned and characterized. MdTPS promoter was analyzed, and its transcriptional activity was verified in vitro by Sf9 cell. Quantitative RT-PCR analysis revealed that the MdTPS transcription was up-regulated following bacterial challenge by Escherichia coli or Staphylococcus aureus. Meanwhile, trehalose is accumulated in larvae upon bacterial challenge. Significantly increased mortality can be observed in MdTPS depleted (RNA interference, RNAi) larvae under bacterial infection. Interestingly, feeding trehalose led to increasing trehalose content in larvae, and the effects of RNAi targeting MdTPS on host survival against bacterial challenge was partly counteracted. Taken together, these results suggest that MdTPS acts as an inducible anti-stress gene that takes part in immune defense in M. domestica via synthesizing its product trehalose.

A house fly TNF ortholog Eiger regulates immune defense via cooperating with Toll and Imd pathways

In mammals, the TNF family is important inflammatory cytokines. Eiger, the invertebrate ortholog of TNF identified firstly in Drosophila, has been implicated in immune response with an unknown molecular mechanism. The present work reports a novel eiger like gene (Mdeiger) from Musca domestica. Mdeiger was significantly up-regulated upon challenge with either Escherichia coli or Staphylococcus aureus. Silencing Mdeiger led to higher mortalities of larvae post either E. coli or S. aureus infection, enhanced the expressions of attacin and diptericin, but blocked the induction of ceropin and muscin, and inhibited the activation of phenoloxidase following bacterial challenge. Meanwhile, the expression of dorsal and JNK was inhibited while that of relish was enhanced in Mdeiger-depleted larvae. We suppose that, by coordinating with the Imd, Toll and JNK pathways, Mdeiger be involved in regulating the innate immune response through controlling the capacity of phenoloxidase and the expression of antimicrobial peptide genes synergistically.

Evaluation of Beauveria bassiana infection in the hemolymph serum proteins of the housefly, Musca domestica L. (Diptera: Muscidae)

Beauveria bassiana plays a prominent role in biocontrol of houseflies, Musca domestica (L.). Thus, a deeper insight into immune response of M. domestica during B. bassiana infection was warranted to assist the production of more efficient mycoinsecticides. The present study investigates changes in protein profile of M. domestica hemolymph serum post B. bassiana infection using two-dimensional difference gel electrophoresis (2D-DIGE) followed by identification of selected proteins by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). The non-infected or control group of flies showed an expression of 54 proteins, while M. domestica infected with B. bassiana expressed a total of 68 hemolymph serum proteins. Thirty three proteins were expressed in both groups of houseflies, whereas 35 proteins were exclusively expressed in infected flies and 21 proteins were exclusively expressed in control flies. Among the 33 proteins which were expressed in both groups of houseflies, 17 proteins showed downregulation, while16 proteins were upregulated in the infected flies compared to the non-infected ones. The results from this study are expected to facilitate better understanding of insect's immune response mechanism.

Campylobacter jejuni in Musca domestica: An examination of survival and transmission potential in light of the innate immune responses of the house flies

The house fly, Musca domestica, has been implicated as a vector of Campylobacter spp., a major cause of human disease. Little is known whether house flies serve as biological amplifying hosts or mechanical vectors for Campylobacter jejuni. We investigated the period after C. jejuni had been ingested by house flies in which viable C. jejuni colonies could be isolated from whole bodies, the vomitus and the excreta of adult M. domestica and evaluated the activation of innate immune responses of house flies to ingested C. jejuni over time. C. jejuni could be cultured from infected houseflies soon after ingestion but no countable C. jejuni colonies were observed > 24 h postingestion. We detected viable C. jejuni in house fly vomitus and excreta up to 4 h after ingestion, but no viable bacteria were detected ≥ 8 h. Suppression subtractive hybridization identified pathogen-induced gene expression in the intestinal tracts of adult house flies 4-24 h after ingesting C. jejuni. We measured the expression of immune regulatory (thor, JNK, and spheroide) and effector (cecropin, diptericin, attacin, defensing, and lysozyme) genes in C. jejuni-infected and -uninfected house flies using quantitative real time PCR. Some house fly factor, or combination of factors, eliminates C. jejuni within 24 h postingestion. Because C. jejuni is not amplified within the body of the housefly, this insect likely serves as a mechanical vector rather than as a true biological, amplifying vector for C. jejuni, and adds to our understanding of insect-pathogen interactions.

Characterization and Expression Pattern Analysis of the T-Complex Protein-1 Zeta Subunit in Musca domestica L (Diptera)

Chaperonins, belonging to the T-complex protein-1 (TCP-1) family, assist in the correct folding of nascent and misfolded proteins. It is well-known that in mammals, the zeta subunit of the TCP-1 complex (TCP-1ζ) plays a vital role in the folding and assembly of cytoskeleta proteins. This study reported for the first time the cloning, characterization and expression pattern analysis of the TCP-1ζ from Musca domestica, which was named as MdTCP-1ζ. The MdTCP-1ζ cDNA is 1,803 bp long with a 1,596 bp open reading frame that encodes a protein with 531 bp amino acids. The analysis of the transcriptional profile of MdTCP-1ζ using qRT-PCR revealed relatively high expression in the salivary glands and trachea at the tissues while among the developmental stages. The highest expression was observed only in the eggs suggesting that the MdTCP-1ζ may play a role in embryonic development. The expression of MdTCP-1ζ was also significantly induced after exposure to short-term heat shock and infection by Escherichia coli, Staphylococcus aureus, or Candida albicans. This suggested that MdTCP-1ζ may take part in the immune responses of housefly and perhaps contribute to the protection against cellular injury.

The effect of Beauveria bassiana infection on cell mediated and humoral immune response in house fly, Musca domestica L

Entomopathogenic fungi that manifest infections by overcoming insect's immune response could be a successful control agent for the house fly, Musca domestica L. which is a major domestic, medical, and veterinary pest. In this study, the immune response of house fly to Beauveria bassiana infection was investigated to reveal fundamental aspects of house fly hemocyte biology, such as hemocyte numbers and size, which is poorly understood. The total hemocyte counts (THCs) in B. bassiana-infected house fly showed an initial increase (from 6 to 9 h), followed by subsequent decrease (9 to 12 h) with increase in time of infection. The THCs was slightly greater in infected flies than the non-infected ones. Insight into relative hemocyte counts depicted a significant increase in prohemocyte (PR) and decrease in granulocyte (GR) in infected house flies compared to non-infected ones. The relative cell area of hemocyte cells showed a noticeable increase in PR and intermediate cells (ICs), while a considerable reduction was observed for plasmatocyte (PL) and GR. The considerable variation in relative cell number and cell area in the B. bassiana-infected house flies indicated stress development during infection. The present study highlights changes occurring during B. bassiana invasion to house fly leading to establishment of infection along with facilitation in understanding of basic hemocyte biology. The results of the study is expected to help in better understanding of house fly immune response during fungal infection, so as to assist production of more efficient mycoinsecticides for house fly control using B. bassiana.

A Comparative Study of Skin Prick Test versus Serum-Specific IgE Measurement in Indian Patients with Bronchial Asthma and Allergic Rhinitis

BACKGROUND

Skin prick testing (SPT) is the 'gold standard' in the assessment of allergic sensitivity to inhalant allergens. Serum-specific immunoglobulin E (SSIgE) measurement is a complementary test. SPT is performed with antigen extracts from India while SSIgE utilises extracts derived from European antigens.

OBJECTIVE

To evaluate the performance of allergic assessment by SSIgE against cockroach, housefly and mosquito aeroallergens which are frequently implicated in driving respiratory allergies in India considering SPT as the 'gold standard'.

METHODS

Twenty patients (mean age 28.5 years; range 15-50 years) diagnosed to have bronchial asthma and/or rhinitis underwent SPT. The SSIgE levels were obtained at the same visit. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of SSIgE testing were calculated using SPT as the 'gold standard'. The correlation between SPT grading and SSIgE levels was also evaluated.

RESULTS

The sensitivity of SSIgE testing to each of the 3 aero-allergens was > 85%. The PPV of cockroach and mosquito SSIgE was > 85%; housefly SSIgE had PPV of 68.7%. The two tests were in agreement in 85% (cockroach), 90% (mosquito) and 55% (housefly). There was a significant correlation between the grades of SPT reactions and SSIgE levels.

CONCLUSIONS

The SSIgE has higher sensitivity and PPV, but lacks specificity. Higher sensitivity with low specificity leads to increased false positive diagnosis of allergic disease. Unlike allergenic pollens, however, insect antigen extracts from different regions seem to give comparable results, and can thus, reliably be used in the evaluation of allergy.

Transcriptional response of Musca domestica larvae to bacterial infection

The house fly Musca domestica, a cosmopolitan dipteran insect, is a significant vector for human and animal bacterial pathogens, but little is known about its immune response to these pathogens. To address this issue, we inoculated the larvae with a mixture of Escherichia coli and Staphylococcus aureus and profiled the transcriptome 6, 24, and 48 h thereafter. Many genes known to controlling innate immunity in insects were induced following infection, including genes encoding pattern recognition proteins (PGRPs), various components of the Toll and IMD signaling pathways and of the proPO-activating and redox systems, and multiple antimicrobial peptides. Interestingly, we also uncovered a large set of novel immune response genes including two broad-spectrum antimicrobial peptides (muscin and domesticin), which might have evolved to adapt to house-fly's unique ecological environments. Finally, genes mediating oxidative phosphorylation were repressed at 48 h post-infection, suggesting disruption of energy homeostasis and mitochondrial function at the late stages of infection. Collectively, our data reveal dynamic changes in gene expression following bacterial infection in the house fly, paving the way for future in-depth analysis of M. domestica's immune system.

Pseudomonas aeruginosa in Musca domestica L.: temporospatial examination of bacteria population dynamics and house fly antimicrobial responses

House flies associate with microbes throughout their life history. Bacteria ingested by adult flies enter the alimentary canal and face a hostile environment including antimicrobial defenses. Because the outcome of this interaction impacts bacterial survival and dissemination, our primary objective was to understand the temporospatial dynamics of fly-bacteria associations. We concurrently examined the temporospatial fate of GFP-expressing Pseudomonas aeruginosa (GFP-P. aeruginosa) in the house fly alimentary canal along with antimicrobial peptide (AMP) expression. Motile, viable GFP-P. aeruginosa were found in all regions of the alimentary canal and were culturable throughout the observation period (2–24 h). A significant decrease in recoverable bacteria occurred between 2 and12 h, followed by an increase between 12 and 24 h. qRT-PCR analysis showed expression of the AMPs cecropin, diptericin, and defensin both locally (gut) and systemically. Furthermore, mRNA of all AMPs were expressed throughout gut tissues, with some tissue-specific temporal variation. Interestingly, fluctuation in recoverable P. aeruginosa was associated with AMP protein expression in the gut (immunofluorescent signal detection), but not with mRNA (qRTPCR). In regards to vector competence, flies excreted GFP-P. aeruginosa throughout the 24 h period, serving as both reservoirs and disseminators of this bacterium. Collectively, our data show flies can harbor and disseminate P. aeruginosa, and that the interactions of fly defenses with bacteria can influence vector competence.

Staphylococcus aureus in the house fly: temporospatial fate of bacteria and expression of the antimicrobial peptide defensin

House flies disseminate numerous species of bacteria acquired during feeding and breeding activities in microbe-rich habitats. Previous house fly surveys have detected the pathogen Staphylococcus aureus Rosenbach 1884, which causes cutaneous and septic infections in mammals, and enterotoxic food poisoning. We assessed the fate of GFP-expressing S. aureus (GFP-S. aureus) in the house fly alimentary canal with microscopy and by culture of whole flies and excreta. Furthermore, the concurrent expression of the antimicrobial peptide gene defensin was measured in the crop, proventriculus, midgut, and fat body. As soon as 4 h postingestion (PI), GFP-S. aureus were visualized as cocci or diplococci in the hindgut and rectum of flies fed approximately equal 10(5) colony forming units. Bacteria persisted up to 6 h PI but significantly decreased. Excretion of viable GFP-S. aureus peaked at 2 h PI and, although significantly less, continued up to 4 h PI. defensin was highly upregulated locally in the alimentary canal and systemically in fat body at 2, 4, and 6 h PI making this study the first to report, to our knowledge, an epithelial and systemic response to a bacterium with lysine-type peptidoglycan in flies exposed via feeding. While flies harbored S. aureus for up to 6 h PI, the highest probability of vectoring biologically relevant amounts of bacteria occurred 0-2 h PI. The combined effects of excretion, digestion and antimicrobial effectors likely contribute to loss of ingested bacteria. Nonetheless, house flies are relevant vectors for S. aureus up to 2 h PI and environmental reservoirs up to 6 h PI.

Antiviral, immunomodulatory, and free radical scavenging activities of a protein-enriched fraction from the larvae of the housefly, Musca domestica

In our previous study, protein-enriched fraction (PEF) that was isolated from the larvae of the housefly, Musca domestica L. (Diptera: Muscidae), showed excellent hepatoprotective activity as well as the potential for clinical application in therapy for liver diseases. In this study, antiviral, immunomodulatory, and free radical scavenging activities of PEF were evaluated. The antiviral results demonstrated that PEF inhibited the infection of avian influenza virus H9N2 and had a virucidal effect against the multicapsid nucleopolyhedrovirus of the alfalfa looper, Autographa californica Speyer (Lepidoptera: Noctuidae) in vitro. The mortality of silkworm larve in a PEF treatment group decreased significantly compared with a negative control. PEF showed excellent scavenging activity for 1,1-diphenyl-2-picrylhydrazyl and superoxide anion radicals, which were similar to those of ascorbic acid. The imunomodulatory results suggested that PEF could effectively improve immune function in experimental mice. Our results indicated that PEF could possibly be used for the prophylaxis and treatment of diseases caused by avian influenza virus infection. In addition, PEF with virucidal activity against insect viruses might provide useful for the development of antimicrobial breeding technology for economically important insects. As a natural product from insects, PEF could be a potential source for the discovery of potent antioxidant and immunomodulatory agents.

Stress-induced HSP70 from Musca domestica plays a functionally significant role in the immune system

As important molecular chaperones, members of the 70kDa heat shock protein (HSP70) family play essential roles in stress tolerance and innate immunity in organisms. The full-length complementary DNA (cDNA) of a novel inducible HSP70, named as MdHSP70, was isolated from Musca domestica. The cDNA clone consisted of 2411 bp with a 1956 bp open reading frame which encodes 651 amino acids. Using real-time quantitative polymerase chain reaction (qPCR), we investigated the transcriptional profile of the gene under heat shock, cadmium stress and in response to bacteria. Increased expression of MdHSP70 was observed in response to both heat shock and Cd stress. The expression of MdHSP70 was significantly induced by Escherichia coli or Staphylococcus aureus stimulation. Larvae were fed bacteria expressing dsRNA targeting the MdHSP70 gene. Our results showed high mortality in larvae treated with dsRNA of MdHSP70 at heat shock, Cd stress and bacterial invasion, suggesting that MdHSP70 is potentially involved in the stress and immune responses of the house fly and perhaps contributes to protection against cellular injury.

Effects of heavy metals on insect immunocompetent cells

The influence of the following heavy metals, copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb), on haemocytes of the house fly Musca domestica L. was studied under laboratory conditions. House fly larvae were exposed to low or high, semi-lethal concentrations of metals. These particular metals were selected because they are present in polluted environments in Poland. In addition, we studied expression of the stress proteins HSP70 and HSP72 in haemocytes collected from larvae that had been exposed to heavy metal. The obtained results showed changes in haemocytes morphology and phagocytotic plasticity in the experimental flies in comparison to control. The number of prohaemocytes, regarded as stem cells, increased, while granulocytes, responsible for phagocytosis, decreased. However, we have not detected any clear changes in expression of HSP70 or HSP72 in flies treated with low or high concentrations of the heavy metals.

A case for sequencing the genome of Musca domestica (Diptera: Muscidae)

House flies are carriers of >100 devastating diseases that have severe consequences for human and animal health. Despite the fact that it is a passive vector, a key bottleneck to progress in controlling the human diseases transmitted by house flies is lack of knowledge of the basic molecular biology of this species. Sequencing of the house fly genome will provide important inroads to the discovery of novel target sites for house fly control, understanding of the house fly immune response, rapid elucidation of insecticide resistance genes, and understanding of numerous aspects of the basic biology of this insect pest. The ability of the house fly to prosper in a remarkably septic environment motivates analysis of its innate immune system. Its polymorphic sex determination system, with male-determining factors on either the autosomes or the Y chromosome, is ripe for a genomic analysis. Sequencing of the house fly genome would allow the first opportunity to study the interactions between a pest insect and its parasitoid (Nasonia vitripennis) at the whole genome level. In addition, the house fly is well placed phylogenetically to leverage analysis of the multiple Dipteran genomes that have been sequenced (including several mosquito and Drosophila species). The community of researchers investigating Musca domestica are well prepared and highly motivated to apply genomic analyses to their widely varied research programs.

Anaphylaxis to Hippobosca equina (louse fly)

BACKGROUND

IgE-mediated allergy to insects different from Hymenoptera species is seldom reported.

OBJECTIVE

To describe and study the case of a previously nonatopic man with an anaphylactic reaction (grade III, Müeller) caused by a bite from a louse fly (Hippobosca equina).

METHODS

In vivo (skin prick tests) and in vitro (enzyme-linked immunosorbent assay and sodium dodecyl sulfatepolyacrylamide gel electrophoresis immunoblotting) tests were used for diagnosis. Cross-reactivity between H. equina and different insects was investigated.

RESULTS

Results of skin prick tests and serum specific IgE were positive to H. equina. Immunoblot inhibition studies identified common bands in H. equina, Apis mellífera, and Musca domestica, but this cross-reactivity did not affect a band of 16 or 15 kDa. This molecular weight is similar to that of phospholipase A2 in A mellifera venom.

CONCLUSION

We describe a case of IgE-mediated allergy to H. equina in which specific molecular band proteins seemed to be responsible for the reaction.

[Occupational inhalant allergy to the common housefly (Musca domestica)]

Isolated allergy to the common housefly (Musca domestica) has only been described in four cases. Predisposing factors include high concentrations of allergens and prolonged exposure time. Two pharmaceutical industry workers, 59 and 34 years of age, both without atopy, presented with recent onset of allergic rhinitis. Their symptoms appeared about 30 minutes after exposure to Musca domestica in the closed breeding rooms. They were symptom-free with other insects, on weekends and on vacation. Skin prick tests with common inhalant allergens were negative. Prick testing with crushed Musca domestica adults, hatched eggs, contaminated nets and sand, as well as fly feces were all positive. One patient had specific IGE antibodies against Musca domestica. Both patients lacked specific IgE antibodies against other insect species and common aeroallergens. In these two patients there was a species-specific sensitization without relevant cross reactions to other arthropods. The patients were transferred to new work sites where they had no contact with Musca domestica and became symptom-free. Thus this common insect can be a relevant occupational aeroallergen.

[SDS-PAGE analysis of the antibacterial activity of the hemolymph from housefly larva]

OBJECTIVE

To study the inducible antibacterial activity of the hemolymph from housefly larva and analyze the antibacterial molecules.

METHODS

The hemolymph was collected from the third instar housefly larvae 48 h after pricking treatment. Nine standard bacterial strains were used for determination of the antibaterial activity of the collected hemolymph and its combination with ampicillin. The anti-yeast activity of the hemolymph and its mixture with fluconazol was also assayed. The antibacterial molecules in the hemolymph was analyzed by SDS-PAGE.

RESULTS

The growth of E.coli, Staphylococcus aureus, Staphylococcus albus, subserotypes of Shigeila flexneri, Bacillus proteus, Bacillus subtilis, Bacillus typhi, Bacillus paratyphosus, and Micrococcus lysodeikticus could be inhibited by the hemolymph collected from housefly larva, and the effect differed significantly between the groups (Plt;0.001). The hemolymph produced the strongest antibacterial activity against Micrococcus lysodeikticus, and the combination of the hemolymph with ampicillin most conspicuously inhibited the growth of Staphylococcus albus. The hemolyph and fluconazol exhibited obvious synergistic effect against yeast. SDS-PAGE identified some specific antibacterial molecules in the hemolymph.

CONCLUSION

The induced hemolymph from housefly larva possesses strong antibacterial and antifungal activities especially against Micrococcus lysodeikticus. The hemolymph in combination with ampicillin produces the strongest effect against Staphylococcus albus, and fluconazol can significantly enhance the anti-yeast activity of the hemolymph through a synergistic mechanism.

Importance of tropomyosin in the allergy to household arthropods. Cross-reactivity with other invertebrate extracts

The aim of the study was to investigate the involvement of the actin binding protein tropomyosin in the allergic sensitization of patients to household arthropods, as well as to study its panallergenic character in relation to other invertebrate extracts. Three arthropod extracts were prepared, namely fly (Musca domestica), moth (Ephestia spp.) and spider (Tegenaria spp.), and used to evaluate by cutaneous and RAST tests a population of 100 household arthropod allergic patients. Twenty-nine sera were selected for the subsequent SDS-PAGE Immunoblotting assays. IgE binding bands at 36, 34, 31, 27 and 17 kDa were detected in the fly extract by more than 50% of tested sera. In moth and spider extracts, the more relevant allergens were found at 34, 31, 24 and 110, 38, 35, 26, 19 kDa, respectively. A commercial polyclonal antiserum anti-chicken muscle tropomyosin was used for tropomyosin identification. Cross-reactivity studies performed by SDS-PAGE Immunoblotting, using a pool of household arthropod allergic patients and tropomyosin antiserum, preliminarily demonstrated the presence of such protein as a cross-reacting allergen in a large variety of extracts obtained from insects, mites, crustaceans, mollusks and parasites.

The product of the Drosophila melanogaster segment polarity gene armadillo is highly conserved in sequence and expression in the housefly Musca domestica

Segmental pattern in Drosophila melanogaster is set up via a set of cell-cell interactions mediated by the products of the segment polarity genes. Among these is the armadillo gene, whose product seems to be required for the reception of an intercellular signal encoded by the wingless gene. As part of our effort to relate the structure of the armadillo protein to its function within the cell, we have examined the evolutionary conservation of the armadillo gene during insect evolution. We have cloned the armadillo gene from the housefly, Musca domestica, which diverged from Drosophila 100 million years ago. The Musca protein is 97.5% identical to that in Drosophila, while the noncoding sequences have diverged extensively. This remarkable degree of conservation at the protein level is mirrored in the expression pattern of the armadillo protein. Antibodies against the Drosophila protein cross-react with a Musca protein of the appropriate size. We have also used these antibodies to show that the Musca armadillo protein has a pattern of expression in larval and adult tissues similar to that of Drosophila armadillo. We discuss the implications of conservation of structure and expression for the cellular role of the armadillo protein and its mammalian homologs.

Occupational allergy to the common house fly. (Musca domestica): use of immunologic response to identify atmospheric allergen

A 48-year-old scientific worker developed rhinitis that occurred when she entered the housefly (Musca domestica) rearing room where she worked. She was found to have specific IgE antibody to M. domestica in her serum by RAST. She was relocated at work and avoided further occupational exposure to M. domestica. The level of specific IgE decreased in serial samples but subsequently increased after her inadvertent reexposure at work. Extracts of fly-cage dust and of high volume atmospheric samples from the fly-rearing room inhibited the M. domestica RAST in a dose-dependent fashion. After logit transformation the lines of inhibition of the fly cage dust and of the atmospheric samples were parallel and steeper than the self-inhibition by M. domestica, implying the cage dust and atmospheric samples shared antigens not present in the M. domestica extract. This method of monitoring atmospheric antigen has considerable potential for evaluating the effectiveness of environmental change in the workplace.