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PubMed1998

Houseflies are an unlikely reservoir or vector for Helicobacter pylori.

The route of transmission of Helicobacter pylori from individual to individual remains undefined. It has recently been reported that the domestic housefly, Musca domestica, when fed pure cultures of H. pylori, was able to harbor the organism in its midgut for up to 30 h (P. Grubel, S. Hoffman, F. K. Chong, N. A. Barstein, C. Mepani, and D. R. Cave, J. Clin. Microbiol. 35:1300-1303, 1997). Our investigation examined whether houseflies could acquire H. pylori from fresh human feces. Domestic houseflies (40 flies/group) were exposed for 24 h to feces from an H. pylori-positive volunteer, feces from an H. pylori-negative volunteer, or feces from an H. pylori-negative volunteer to which a known amount of viable H. pylori had been added. At various intervals, flies were sacrificed and the midguts were excised, homogenized, and plated in duplicate onto selective horse blood agar plates. All plates were incubated under microaerobic conditions at 37 degreesC for 14 days. Emergent colonies presumptive of H. pylori were picked and tested biochemically to confirm the identity as H. pylori. H. pylori was not recovered from houseflies fed human feces either naturally infected or artificially infected with H. pylori. These results suggest that the domestic housefly is not a vector for transmission or a reservoir for H. pylori infection.

Animals↗

PubMed2004

Studies on the carriage and transmission of porcine reproductive and respiratory syndrome virus by individual houseflies (Musca domestica).

The objectives of the study were to determine the site of porcine reproductive and respiratory syndrome virus (PRRSV) in individual houseflies, to assess whether an individual housefly could transmit PRRSV to a susceptible pig, and to compare the ability of PCR, virus isolation and a pig bioassay to detect PRRSV in houseflies. In the first experiment 26 houseflies were fed on a pig infected experimentally with PRRSV; 13 were processed as a whole fly homogenate, while an exterior surface wash and a gut homogenate were collected from the other 13. Infectious PRRSV was recovered from nine of the whole fly homogenates, 12 of the gut homogenates and one of the exterior surface washes. In the second experiment, two of 10 individual houseflies, which had fed on an infected pig, transmitted PRRSV to a susceptible pig in a controlled manual transmission protocol. In the third experiment, single flies or pools of 30 flies were immersed in different concentrations of a PRRSV inoculum, then tested by PCR, virus isolation and bioassay. The virus was detected at a concentration of 10(1) TCID50/ml by PCR, 10(2) TCID50/ml by the bioassay and 10(3) TCID50/ml by virus isolation.

Animals↗

PubMed1999

Houseflies: not simple mechanical vectors of enterohemorrhagic Escherichia coli O157:H7.

An epidemic of enterohemorrhagic colitis caused by Escherichia coli O157:H7 (EHEC-O157) occurred in a nursery school in a rural area of Japan in September 1996. The EHEC-O157 were isolated both from patients and houseflies collected at the school. The flies were suspected to be mechanical vectors of the pathogen. Feeding experiments of EHEC-O157 to houseflies showed that the ingested bacteria were harbored in the intestine of flies and continued to be excreted at least for 3 days after feeding. Scanning electron microscopy showed that a large number of EHEC-O157 adhered to the surface of the housefly mouthparts and actively proliferated in the minute spaces of the labellum. Food masses containing EHEC-O157 in the fly intestine were completely surrounded by a peritrophic membrane during digestion and discharged rapidly. The persistence of bacteria in the intestine and feces is mainly a result of proliferation in the mouthparts and accumulation in the crop. Our results strongly suggest that houseflies are not simple mechanical vectors of EHEC. The epidemiologic potential of houseflies to disseminate EHEC-O157 may be greater than initially suspected.

Animals↗

PubMed2000

Isolation of Salmonella spp. from the housefly, Musca domestica L., and the dump fly, Hydrotaea aenescens (Wiedemann) (Diptera: Muscidae), at caged-layer houses.

Flies, especially houseflies, are widely recognized as potential reservoirs and vectors of foodborne Salmonella pathogens. In this study, flies were collected at caged-layer facilities that had produced eggs that were implicated as the food vehicle in two recent outbreaks of Salmonella Enteritidis infections. The flies were separated by species into pools for microbiological testing. A total of 15 species pools of houseflies, Musca domestica L., and 7 species pools of bronze dump flies, Hydrotaea aenescens (Wiedemann) (Diptera: Muscidae), were analyzed. Salmonella Enteritidis was isolated from 2 of the 15 pools of houseflies. Other species of Salmonella were isolated from three pools of flies, including Salmonella Infantis from houseflies and from dump flies and Salmonella Heidelberg from houseflies. Salmonella Mbandaka was isolated from a lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae).

Animals↗

PubMed2003

Development of PDF-immunoreactive cells, possible clock neurons, in the housefly Musca domestica.

Even though the housefly Musca domestica shows clear circadian rhythms in its behavioural and physiological processes, a circadian pacemaker system controlling these rhythms has not yet been described morphologically in this species. In M. domestica, neurons immunoreactive to pigment-dispersing factor (PDF), a neurotransmitter/neuromodulator of circadian information arising from a circadian clock and transmitted to target cells, are similar in their number and distribution to the PDF neurons of Drosophila melanogaster. In D. melanogaster these neurons co-localize PER protein and have been identified as clock neurons in that species. Here we report PDF-immunoreactive cells in the housefly's brain during postembryonic development in the larval and pupal stages, as well as in the adult fly soon after eclosion. In the housefly's brain, there are three groups of PDF-immunoreactive neurons: two groups with small (sPDFMe) and large (lPDFMe) cell bodies in the proximal medulla of the optic lobe; and one group in the dorsal protocerebrum (PDFD). Three out of four sPDFMe can be detected during the first hour of larval development, but the fourth sPDFMe is observed in the larva only from 48 hours after hatching, along with five lPDFMe neurons, seen first as two subgroups, and three out of four PDFD neurons. During postembryonic development these neurons show changes in their structure and immunoreactivity. New PDF neurons are observed during pupal development but these neurons mostly do not survive into adulthood. In the adult fly's brain, the PDF neurons have also been examined in double-labelled preparations made with a second antibody directed against the product of one of several clock genes: period (per), timeless (tim), or cryptochrome (cry). Among them, only immunoreactivity to CRY-like protein has been detected in the brain of M. domestica and has shown a daily rhythm in its concentration, as examined immunocytochemically. CRY was co-localized with PDF in the sPDFMe of the housefly's brain fixed during the day. The possibility that the sPDFMe neurons are the housefly's clock neurons is discussed.

Animals↗

PubMed1998

In vitro metabolism of pyriproxyfen by microsomes from susceptible and resistant housefly larvae.

Levels of cytochrome P450 and b5 were investigated in microsomal enzymes of houseflies from the gut and fat body of the third instar larvae of a pyriproxyfen-resistant strain (YPPF) and two pyriproxyfen-susceptible strains (YS and SRS). In comparison to the YS and SRS strains, YPPF microsomes had higher levels of total cytochrome P450s in both the gut and fat body. Furthermore, microsomes from the gut and fat body of YPPF larvae were found to have a much greater ability to hydroxylate aniline than YS larvae. In vitro metabolism studies of pyriproxyfen indicated that the metabolic rates were much higher in both the gut and fat body of YPPF larvae than of YS and SRS larvae. The major metabolites of pyriproxyfen in houseflies were identified to be 4'-OH-pyriproxyfen and 5"-OH-pyriproxyfen. Cytochrome P450 inhibitors, piperonyl butoxide (PB) and 2-propynyl 2,3,6-trichlorophenyl ether (PTPE), decreased the metabolic rates significantly in all three strains. This study confirmed that microsomal cytochrome P450 monooxygenases play an important role in the pyriproxyfen resistance of the housefly. Furthermore, it suggests that the fat body must be as important as the gut for the metabolism of pyriproxyfen in resistant housefly larvae.

Adipose Tissue↗

PubMed1994

Influence of enzyme levels on the toxicity and in vitro metabolism of 2,2',5-trichlorobiphenyl in houseflies.

Adult female houseflies (Musca domestica) were topically dosed with 10, 15, and 20 micrograms of 2,2',5-trichlorobiphenyl (PCB-18) in acetone at 1, 5, and 15 days following emergence. These doses caused a significant decrease in the mean survival time in 5-day-old flies. LT50's (time for 50% death) were dramatically reduced in 5-day-old flies, whereas no significant difference was found at any treatment level in 15-day-old flies. Abdomenal microsomal enzyme levels were determined by the rate of O-dealkylation of (p-nitrophenyl)ethyl ether for 1-, 5-, 11-, and 15-day-old female houseflies. The highest levels were found in 5-day-old flies and the lowest in 15-day-old flies. The greatest metabolism of PCB-18 by housefly microsomes also occurred in 5-day-old flies. The enzyme levels, metabolism, and toxicity suggest that PCB-18 is bioactivated to a product(s) which reduces the mean survival time of houseflies.

Aging↗

PubMed1994

Glutathione transferase gene family from the housefly Musca domestica.

Three new glutathione transferase (GST) genes from the housefly Musca domestica are described. These genes, identified as MdGST-2, -3, and -4, were from cDNA clones obtained from a cDNA bank in phage lambda. The bank was prepared using poly(A)+ RNA from a housefly that is highly resistant to organophosphate insecticides because of enhanced expression of multiple members of the glutathione transferase gene family. The DNA sequence of each is reported and has a complete open reading frame that specified an amino acid sequence similar to other dipteran glutathione transferases. Based on phylogenetic analysis, we can conclude that the insect glutathione transferase gene family falls into two groups, each of which evolves at a different rate, presumably due to differences in functional constraints. We show that MdGST-1 (and their homologues from Drosophila and Lucilia) evolve at a significantly slower rate than the other members of the gene family. Each housefly GST cDNA was inserted into a bacterial plasmid expression system and a glutathione transferase activity was expressed in Escherichia coli. The transcription pattern of each of these glutathione transferases was examined in a variety of different housefly strains that are known to differ in their resistance to organophosphate insecticides due to different patterns of glutathione transferase expression. We found that the level of transcription for two of our clones was positively correlated with the level of organophosphate resistance.

Amino Acid Sequence↗

PubMed2006

Molecular characterization and expression of the antimicrobial peptide defensin from the housefly (Musca domestica).

A 430-bp cDNA encoding the insect antimicrobial peptide defensin was cloned from the housefly, and designated Musca domestica defensin (Mdde). The open reading frame of the cDNA encoded a 92-amino acid peptide with an N-terminal signal sequence followed by a propeptide that is processed by cleavage to a 40-amino acid mature peptide. Northern analysis and in situ hybridization identified the corresponding mRNA in the fat body of bacterially challenged houseflies and in the epidermis of the body wall of naive and challenged houseflies. The Gram-negative bacterium (Escherichia coli) is a strong inducer of the gene. By RT-PCR, Mdde mRNA was also detected in naive and challenged insects. These findings suggest that the defensin gene is constitutively expressed in the epidermis of the housefly body wall. The predicted mature form of Mdde was expressed as a recombinant peptide in E. coli and Pichia pastoris. The recombinant Mdde expressed in Pichia was active against Gram-positive and some Gram-negative bacteria.

Amino Acid Sequence↗

PubMed1985

Effect of age and ambient temperature on n-pentane production in adult housefly, Musca domestica.

The objective of this study was to examine the relationship between lipid peroxidation and aging in the male housefly. Metabolic rate of flies is known to be higher and life span shorter at elevated ambient temperature. Evolution of n-pentane and level of thiobarbituric acid (TBA) reactive material were used as indicators of lipid peroxidation. n-Pentane accumulated by houseflies in vivo and by whole body homogenates of houseflies, in response to tert-butyl hydroperoxide (1 mM), increased with age. n-Pentane accumulation in vivo was markedly higher at higher ambient temperature. Furthermore, n-pentane generated by flies in vivo and by fly homogenates in vitro tended to be lower in flies raised at a lower ambient temperature. TBA-reactive material, elicited by tert-butyl hydroperoxide, was augmented in older flies, but no significant difference was found between flies aged at different ambient temperatures. Analysis of fatty acids in housefly homogenates indicated an age-associated increase in the ratio of polyunsaturated to saturated fatty acids.

Aging↗

PubMed2006

A C-terminal aldehyde analog of the insect kinins inhibits diuresis in the housefly.

The insect kinins are present in a wide variety of insects and function as potent diuretic peptides in flies. A C-terminal aldehyde insect kinin analog, Fmoc-RFFPWG-H (R-LK-CHO), demonstrates stimulation of Malpighian tubule fluid secretion in crickets, but shows inhibition of both in vitro and in vivo diuresis in the housefly. R-LK-CHO reduced the total amount of urine voided over 3 h from flies injected with 1 microL of distilled water by almost 50%. The analog not only inhibits stimulation of housefly fluid secretion by the native kinin Musdo-K, but also by thapsigargin, a SERCA inhibitor, and by ionomycin, a calcium ionophore. The activity of R-LK-CHO is selective, however, as related C-terminal aldehyde analogs do not demonstrate an inhibitory response on housefly fluid secretion. The selective inhibitory activity of R-LK-CHO on housefly tubules represents an important lead in the development of environmentally friendly insect management agents based on the insect kinins.

Aldehydes↗

PubMed1999

Isolation, characterization and biological activity of a diuretic myokinin neuropeptide from the housefly, Musca domestica.

A competitive ELISA employing a polyclonal antiserum raised against leucokinin-I was used to isolate and purify a myokinin (muscakinin) from 1.05 kg of adult houseflies (Musca domestica). Following solid-phase purification, seven HPLC column steps were used to purify 4.8 nmol of leucokinin-immunoreactive material. Sequence analysis and mass spectrometry were consistent with the structure Asn-Thr-Val-Val-Leu-Gly Lys-Lys-Gln-Arg-Phe-His-Ser-Trp-Gly NH2. This peptide was synthesized and co-eluted with the natural peptide on three different HPLC columns. The activities of natural and synthetic muscakinin were identical, with both producing a 4-5 fold increase in fluid secretion by housefly Malpighian tubules at nanomolar concentrations. The presence of a pair of basic residues (Lys-Lys) suggested muscakinin might be processed further, with the peptide pGlu-Arg-Phe-His-Ser-Trp-Gly NH2 being produced by conversion of an N-terminal glutamine to pyroglutamic acid. However, this analog was 1000-fold less active than the intact peptide, comparable to the activity of AK-V which shares the same C-terminal pentapeptide sequence. The diuretic activity of muscakinin is more than double that of a previously identified CRF-related diuretic peptide (Musca-DP) from the housefly, and the two peptides act synergistically in stimulating fluid secretion. Muscakinin also increased the frequency and amplitude of contractions by housefly hindgut which might further contribute to the excretory process.

Amino Acid Sequence↗

PubMed2000

Noncompetitive antagonist-binding sites of rat and housefly gamma-aminobutyric acid receptors display different enantiospecificities for tert-butyl(isopropyl)bicyclophosphorothionate.

The enantiomers of 4-tert-butyl-3-isopropyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2 ]octane 1-sulfide (TBIPPS) were prepared in nine steps from diethyl tert-butylmalonate, and their abilities to compete with [3H]1-(4-ethynylphenyl)-4-n-propyl-2,6,7-trioxabicyclo[2.2.2 ]octane (EBOB), a noncompetitive antagonist of ionotropic gamma-aminobutyric acid (GABA) receptors, at their binding site were investigated using rat brain and housefly head membranes. The (S)-(-)-isomer of TBIPPS (IC50 = 398 nM) was more potent than was the (R)-(+)-isomer of TBIPPS (IC50 = 1220 nM) in rat receptors, while the potencies of (S)-TBIPPS 104 nM) and (R)-TBIPPS (IC50 = 94.4 nM) in housefly receptors were almost the same. The different enantiospecificities of rat and housefly receptors indicate that the three-dimensional structure of the binding site might be different between these receptors. In a region of the rat binding site there might be a steric bulk that interacts less favorably with (R)-TBIPPS than with (S)-TBIPPS, while in the corresponding region of the housefly binding site there might not be such a steric bulk that leads to specificity for these compounds.

Animals↗

PubMed2001

Detection of Aeromonas caviae in the common housefly Musca domestica by culture and polymerase chain reaction.

Aeromonas caviae has been implicated in diarrhoeal disease of livestock and humans. The potential role of houseflies in the epidemiology of this pathogen was investigated by examining the prevalence of A. caviae in houseflies collected from two South Carolina farms and one restaurant. Isolation was accomplished by culture of flies in alkaline peptone water followed by identification with Aeromonas-specific PCR using novel primers (APW-PCR). All isolates cultured from houseflies were identified as A. caviae by biochemical characteristics and direct sequencing approximately 800 bp of the 16S rRNA gene. Aeromonas caviae was detected in 78% (272/349) dairy farm flies, 55% (54/99) pig farm flies and 39% (77/200) restaurant flies. Faeces from cows and pigs at the farms also were positive for A. caviae (58% and 100%, respectively). The APW PCR method provided a rapid, convenient way to identify A. caviae from faeces and houseflies that contained hundreds of bacterial species.

Aeromonas↗

PubMed1998

The efficacy of entomopathogenic nematodes for controlling housefly infestations of intensive pig units.

The efficacy of the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis megidis after formulation into a housefly bait was compared with a commercial bait formulation of methomyl for the control of houseflies in a U.K. pig farm. The housefly infestation was confined to the farrowing unit, which consisted of ten farrowing houses, where two adjacent houses were sequentially re-stocked with pregnant sows at weekly intervals. Shortly after re-stocking, one house was baited with one of the nematode species and the other with methomyl. Significantly fewer flies (P < 0.05) were counted in the houses baited with either S. feltiae or H. megidis than those baited with methomyl. The efficacy of S. feltiae sprayed on to the manure was also compared with methomyl bait. Counts of houseflies carried out in the farrowing cycle before this treatment were not significantly different (P > 0.05); however, significantly fewer flies (P < 0.05) occurred after S. feltiae was sprayed. The efficacy of encapsulated S. feltiae was also compared with methomyl bait and no significant difference was observed (P > 0.05).

Agriculture↗

PubMed1994

DNA oxidative damage and life expectancy in houseflies.

The objective of this study was to explore the relationship between oxidative molecular damage and the aging process by determining whether such damage is associated with the rate of aging, using the adult housefly as the experimental organism. Because the somatic tissues in the housefly consist of long-lived postmitotic cells, it provides an excellent model system for studying cumulative age-related cellular alterations. Rate of aging in the housefly was manipulated by varying the rate of metabolism (physical activity). The concentration of 8-hydroxydeoxyguanosine (80HdG) was used as an indicator of DNA oxidation. Exposure of live flies to x-rays and hyperoxia elevated the level of 8OHdG. The level of 8OHdG in mitochondrial as well as total DNA increased with the age of flies. Mitochondrial DNA was 3 times more susceptible to age-related oxidative damage than nuclear DNA. A decrease in the level of physical activity of the flies was found to prolong the life-span and corresponding reduce the level of 8OHdG in both mitochondrial and total DNA. Under all conditions examined, mitochondrial DNA exhibited a higher level of oxidative damage than total DNA. The 8OHdG levels were found to be inversely associated with the life expectancy of houseflies. The pattern of age-associated accrural of 8OHdG was virtually identical to that of protein carbonyl content. Altoghether, results of this study support the hypothesis that oxidative molecular damage is a causal factor in senescence.

8-Hydroxy-2'-Deoxyguanosine↗

PubMedDate not supplied

Houseflies (Musca domestica) as mechanical vectors of shigellosis.

Houseflies (Musca domestica) are mechanical vectors of Shigella organisms. Seasons during which both flies and cases of dysentery are prevalent often coincide. Houseflies have an affinity for human excrement and, as documented by bacteriologic culture of trapped flies, become contaminated with Shigella organisms following contact with infected human feces. The inoculum required to transmit shigellosis is only 10-10(2). Since houseflies cohabit with humans, they can readily contaminate food and eating utensils. With the advent of insecticides in the 1940s, intervention studies in the United States provided evidence of the role of the housefly in transmission of shigellae. In towns that were exposed to fly-control measures, the density of flies and the prevalence of carriage of Shigella organisms, diarrhea, and mortality due to diarrheal disease among young children all markedly diminished as compared with the situation in control towns. Investigations that quantitate the importance of fly-borne transmission of Shigella organisms relative to other modes of transmission and that provide evaluation of measures to diminish fly-borne transmission are warranted in developing areas.

Animals↗

PubMed1988

The role of the housefly, Musca domestica, in the spread of Aujeszky's disease (pseudorabies).

Starved houseflies were held over a suspension of Aujeszky's virus (PRV-1) for 24-48 h. One group was rinsed in 70% ethanol to kill virus attached to the body surface. No virus was isolated from this group. For the other group the titre of virus decreased more rapidly on the body surface of flies than in the environment. Model experiments demonstrated that the Aujeszky's virus cannot survive in the body of the housefly but the body surface may be contaminated for a period of time depending on the initial viral titre. Experiments showed that susceptible pigs fed on flies contaminated with Aujeszky's virus may become infected. The quantity of virus (5 x 10(5) pfu ml-1) shed by a single housefly during biting and vomiting on the cornea or abraded skin proved to be sufficient to cause infection in susceptible pigs, rabbits and a lamb. It is possible that houseflies could play a role in transmission of infection within herds. Transmission between herds is much less likely.

Animals↗