Fungal artillery of zombie flies: infectious spore dispersal using a soft water cannon.

Dead sporulating female fly cadavers infected by the house fly-pathogenic fungus Entomophthora muscae are attractive to healthy male flies, which by their physical inspection may mechanically trigger spore release and by their movement create whirlwind airflows that covers them in infectious conidia. The fungal artillery of E. muscae protrudes outward from the fly cadaver, and consists of a plethora of micrometric stalks that each uses a liquid-based turgor pressure build-up to eject a jet of protoplasm and the initially attached spore. The biophysical processes that regulate the release and range of spores, however, are unknown. To study the physics of ejection, we design a biomimetic 'soft cannon' that consists of a millimetric elastomeric barrel filled with fluid and plugged with a projectile. We precisely control the maximum pressure leading up to the ejection, and study the cannon efficiency as a function of its geometry and wall elasticity. In particular, we predict that ejection velocity decreases with spore size. The calculated flight trajectories under aerodynamic drag predict that the minimum spore size required to traverse a quiescent layer of a few millimetres around the fly cadaver is approximately 10 µm. This corroborates with the natural size of E. muscae conidia (approx. 27 µm) being large enough to traverse the boundary layer but small enough (less than 40 µm) to be lifted by air currents. Based on this understanding, we show how the fungal spores are able to reach a new host.

Sources of microbial oils with emphasis to Mortierella (Umbelopsis) isabellina fungus.

The last years a constantly rising number of publications have appeared in the literature in relation to the production of oils and fats deriving from microbial sources (the "single cell oils"-SCOs). SCOs can be used as precursors for the synthesis of lipid-based biofuels or employed as substitutes of expensive oils rarely found in the plant or animal kingdom. In the present review-article, aspects concerning SCOs (economics, biochemistry, substrates, technology, scale-up), with emphasis on the potential of Mortierella isabellina were presented. Fats and hydrophilic substrates have been used as carbon sources for cultivating Zygomycetes. Among them, wild-type M. isabellina strains have been reported as excellent SCO-producers, with conversion yields on sugar consumed and lipid in DCW values reported comparable to the maximum ones achieved for genetically engineered SCO-producing strains. Lipids produced on glucose contain γ-linolenic acid (GLA), a polyunsaturated fatty acid (PUFA) of high dietary and pharmaceutical importance, though in low concentrations. Nevertheless, due to their abundance in oleic acid, these lipids are perfect precursors for the synthesis of 2nd generation biodiesel, while GLA can be recovered and directed to other usages. Genetic engineering focusing on over-expression of Δ6 and Δ12 desaturases and of C16 elongase may improve the fatty acid composition (viz. increasing the concentration of GLA or other nutritionally important PUFAs) of these lipids.

Diet influences the bacterial and free fatty acid profiles of the cuticle of Galleria mellonella larvae.

The evolutionary success of insects is arguably due to their ability to build up a complex, highly-adaptable and very effective defense system against numerous pathogens, including entomopathogenic fungi. This system relies on the humoral immune system and cellular defense reactions. The first line of defense against biological pathogens is a cuticle formed of several layers. The cuticular lipids may contain hydrocarbons, free fatty acids (FFA), alcohols, waxes, glycerides, aldehydes and sterols. Cuticular fatty acids may also play a role in defending against fungal invasion. Our present findings show that the diet of insects can have a significant effect on their sensitivity and defense response to pathogens; for example, while G. mellonella larvae fed on beeswax had a similar appearance to those reared on a semi-artificial diet, they possessed a different cuticular free fatty acid (FFA) profile to those fed on a semi-artificial diet, and were less sensitive to Conidiobolus coronatus infection. It is possible that the presence of heneicosenoic acid (C21:1) and other long-chain free fatty acids (C22:0, C24:0, C26:0), as well as Brevibacillus laterosporus bacteria, on the cuticle of larvae fed on beeswax, plays a protective role against fungal invasion. Insect pests represent a global problem. An understanding of the basic mechanisms underlying the fungal infection of insects might provide a clearer insight into their defenses, thus allowing the design of more effective, and environmentally-friendly, means of controlling them. The greater wax moth is an excellent model for the study of immunology resistance. Knowledge of the influence of diet on pathogen resistance in insects can be also useful for creating a model of human diseases caused by pathogens, such as Candia albicans.

Identification of fungal pathogens in a patient with acute myelogenic leukemia using a pathogen detection array technology.

Invasive zygomycosis in immunocompromised patients results in a high mortality rate, and early identification is crucial to optimize therapy and to reduce morbidity. However, diagnosing specific species of zygomycetes fungi possess challenge in the clinical laboratories. A need for a rapid and sensitive diagnostic tool for early recognition of a zygomycetes fungus in clinical samples to the species level will lead to prompt and accurate therapy and the PathoChip provides one such platform. We utilized a pathogen array technology referred to as PathoChip, comprised of oligonucleotide probes that can detect all the sequenced viruses as well as known pathogenic bacteria, fungi and parasites and family-specific conserved probes, thus providing a means for detecting previously uncharacterized members of a family. We rapidly identified a zygomycetous fungus, Rhizomucor pusillus, an otherwise challenge for the clinical laboratories, predominantly in a patient with acute myelogenous leukemia. This report highlights the value of PathoChip as a diagnostic tool to identify micro-organisms to the species level, especially for those difficult to identify in most clinical laboratories. It will also help clinicians to obtain a critical snapshot of the infection profile of a patient to plan treatment strategies.

Cutaneous zygomycosis associated with urate panniculitis.

Cutaneous zygomycosis is being increasingly recognized as a serious and life-threatening infection in debilitated and immunosuppressed patients, including transplant patients. The organisms are morphologically distinct but difficult to grow in cultures from clinical samples. We report a case of cutaneous zygomycosis in a neonatal multi-visceral organ transplant patient, with subcutaneous panniculitis accompanied by extensive local acicular uric acid crystal deposition. Although the patient's serum uric acid was subsequently found to be in the normal range, transient hyperuricemia could not be excluded. Because we use a microwave-based processing system avoiding aqueous solutions, the crystals were maintained in the tissue sections and were shown by various methods to consist of monosodium urate. Early diagnosis combined with extensive debridement and prompt antifungal therapy resulted in a successful outcome. We have coined the term "urate panniculitis" to describe this phenomenon.

Iron gathering of opportunistic pathogenic fungi. A mini review.

Iron is an essential nutrient for most organisms because it serves as a catalytic cofactor in oxidation-reduction reactions. Iron is rather unavailable because it occurs in its insoluble ferric form in oxides and hydroxides, while in serum of mammalian hosts is highly bound to carrier proteins such as transferrin, so the free iron concentration is extremely low insufficient for microbial growth. Therefore, many organisms have developed different iron-scavenging systems for solubilizing ferric iron and transporting it into cells across the fungal membrane. There are three major mechanisms by which fungi can obtain iron from the host: (a) utilization of a high affinity iron permease to transport iron intracellularly, (b) production and secretion of low molecular weight iron-specific chelators (siderophores), (c) utilization of a hem oxygenase to acquire iron from hemin. Patients with elevated levels of available serum iron treated with iron chelator, deferoxamine to remedy iron overload conditions have an increased susceptibility of invasive zygomycosis. Presumably deferoxamine predisposes patients to Zygomycetes infections by acting as a siderophore]. The frequency of zygomycosis is increasing in recent years and these infections respond very poorly to currently available antifungal agents, so new approaches to develop strategies to prevent and treat zygomycosis are urgently needed. Siderophores and iron-transport proteins have been suggested to function as virulence factors because the acquisition of iron is a crucial pathogenetic event. Biosynthesis and uptake of siderophores represent possible targets for antifungal therapy.

Breakthrough fungal infections in stem cell transplant recipients receiving voriconazole.

Infection with voriconazole-resistant fungi may become problematic, because organisms with decreased susceptibility have been noted. Breakthrough fungal infections occurred in 13 of 139 patients who received voriconazole at our center during the period of September 1998 through September 2003. Zygomycetes were found in 6 patients, and Candida glabrata bloodstream infection occurred in 4 patients. Minimal inhibitory concentrations were > or =1 microg/mL for all available isolates. Yeasts and molds with decreased susceptibility to voriconazole may cause invasive infection in patients treated successfully for aspergillosis.

Effect of the entomopathogenic fungus, Entomophthora muscae (Zygomycetes: Entomophthoraceae), on sex pheromone and other cuticular hydrocarbons of the house fly, Musca domestica.

House fly (Musca domestica) males are highly attracted to dead female flies infected with the entomopathogenic fungus Entomophthora muscae. Because males orient to the larger abdomen of infected flies, both visual and chemical cues may be responsible for the heightened attraction to infected flies. Our behavioral assays demonstrated that the attraction is sex-specific-males were attracted more to infected females than to infected males, regardless of cadaver size. We examined the effect of E. muscae on the main component of the house fly sex pheromone, (Z)-9-tricosene, and other cuticular hydrocarbons including n-tricosane, n-pentacosane, (Z)-9-heptacosene, and total hydrocarbons of young (7 days old) and old (18 days old) virgin females. Young E. muscae-infected female flies accumulated significantly less sex pheromone and other hydrocarbons on their cuticular surface than uninfected females, whereas the cuticular hydrocarbons of older flies were unaffected by fungus infection. These results suggest that chemical cues other than (Z)-9-tricosene, visual cues other than abdomen size, or a combination of both sets of cues might be responsible for attraction of house fly males to E. muscae-infected females.