title: Uptake of the fluorescent probe FM4-64 by hyphae and haemolymph-derived in vivo hyphal bodies of the entomopathogenic fungus Beauveria bassiana.
abstract: The entomopathogenic fungus Beauveria bassiana is under intensive study as a pest biological control agent. B. bassiana produces several distinct single-cell types that include aerial conidia, in vitro blastospores and submerged conidia. Under appropriate nutrient conditions these cells can elaborate germ tubes that form hyphae, which in turn lead to the formation of a fungal mycelium. In addition, B. bassiana displays a dimorphic transition, producing in vivo specific yeast-like hyphal bodies during growth in the arthropod haemolymph. The amphiphilic styryl dye FM4-64 was used to investigate internalization and morphological features of in vitro and in vivo insect haemolymph-derived B. bassiana cells. In vitro blastospores and submerged conidia displayed a punctate pattern of internal labelling, whereas aerial conidia failed to internalize the dye under the conditions tested. FM4-64 was also taken up into both apical and subapical compartments of living hyphae in a time-dependent manner, with clearly observable vesicle labelling. Internalization, where occurring, was reversibly disrupted by lowering the temperature of the assay or by treatment with azide/fluoride and latrunculin A. Treatment with cytochalasin D and monensin also caused abnormal vesicle trafficking, although some staining of vesicles was noted. Fungal cells derived from infected Heliothis virescens haemolymph (in vivo cells) actively internalized FM4-64. The in vivo blastospores or hyphal bodies displayed bright membrane and internal vesicle staining, although diffuse staining of internal structures was also visible. These results suggest active uptake by different developmental stages of B. bassiana, including haemolymph-derived cells that can evade the insect immune system.
authors: Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA.
authors: Michael W
authors: MW
authors: Lewis
authors: Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA.
authors: Ines V
authors: IV
authors: Robalino
authors: Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA.
authors: Nemat O
authors: NO
authors: Keyhani
mesh_terms: D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D001386:Azides / Q000494:pharmacology; D052982:Beauveria / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000493:pharmacokinetics*; D005459:Fluorides / Q000494:pharmacology; D006458:Hemolymph / Q000382:microbiology*; D025301:Hyphae / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008985:Monensin / Q000494:pharmacology; D009036:Moths / Q000382:microbiology*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010572:Pest Control, Biological; D011726:Pyridinium Compounds / Q000493:pharmacokinetics*; D000644:Quaternary Ammonium Compounds / Q000493:pharmacokinetics*; D013172:Spores, Fungal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D053778:Thiazolidines / Q000494:pharmacology
chemical_list: D000935:Antifungal Agents; D001386:Azides; D019086:Bridged Bicyclo Compounds, Heterocyclic; C092350:FM 4-64; D005456:Fluorescent Dyes; D019384:Nucleic Acid Synthesis Inhibitors; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D053778:Thiazolidines; D015638:Cytochalasin D; D008985:Monensin; D005459:Fluorides; C037067:latrunculin A