Cuticle hydrolysis in four medically important fly species by enzymes of the entomopathogenic fungus Conidiobolus coronatus

Entomopathogenic fungi infect insects via penetration through the cuticle, which varies remarkably in chemical composition across species and life stages. Fungal infection involves the production of enzymes that hydrolyse cuticular proteins, chitin and lipids. Host specificity is associated with fungus–cuticle interactions related to substrate utilization and resistance to host‐specific inhibitors. The soil fungus Conidiobolus coronatus (Constantin) (Entomophthorales: Ancylistaceae) shows virulence against susceptible species. The larvae and pupae of Calliphora vicina (Robineau‐Desvoidy) (Diptera: Calliphoridae), Calliphora vomitoria (Linnaeus), Lucilia sericata (Meigen) (Diptera: Calliphoridae) and Musca domestica (Linnaeus) (Diptera: Muscidae) are resistant, but adults exposed to C. coronatus quickly perish. Fungus was cultivated for 3 weeks in a minimal medium. Cell‐free filtrate, for which activity of elastase, N‐acetylglucosaminidase, chitobiosidase and lipase was determined, was used for in vitro hydrolysis of the cuticle from larvae, puparia and adults. Amounts of amino acids, N‐glucosamine and fatty acids released were measured after 8 h of incubation. The effectiveness of fungal enzymes was correlated with concentrations of compounds detected in the cuticles of tested insects. Positive correlations suggest compounds used by the fungus as nutrients, whereas negative correlations may indicate compounds responsible for insect resistance. Adult deaths result from the ingestion of conidia or fungal excretions.     

Anhydrobiosis in the infective juveniles of Trichostrongylus colubriformis (Nematoda: Trichostrongylidae)

The infective juveniles of Trichostrongylus colubriformis can survive exposure to 0% relative humidity after desiccation at higher relative humidities. During rehydration there is a lag phase before recovery. The infective juveniles are thus capable of anhydrobiosis. Removal of the sheath does not affect desiccation survival but does affect the duration of the lag phase. Morphological changes during the lag phase are described. The appearance of birefringence in the muscle cells during the anomalous shrinkage which occurs during the lag phase is considered to reflect physiological changes necessary for the recovery of normal muscle function.     

Fish cell culture: A new cell line fromCynoscion nebulosus

Summary A new fibroblast-like cell line, CyN, has been developed from muscle tissue of the marine fishCynoscion nebulosus (the spotted weakfish). A subline, CyN-1, was characterized fully and carried through 100 subcultures. CyN-1 is heteroploid and has a modal chromosome number of 49. The line is susceptible to LT-1, lymphocystis, eastern equine encephalitis and vesicular stomatitis viruses. Optimal growth occurred at 25° to 34° C in growth medium adjusted to 0.150m NaCl. This study was supported in part by the National Oceanographic and Atmospheric Administration, Office of Sea Grant No. 04-3-158-58.     

The use of computer-aided learning for teaching parasite life cycles

The difficulty of presenting parasite life cycles in a textual or diagrammatic form is discussed and the use of computer-aided learning to solve this is described. The design and use of a Hypercard stack for teaching parasite life cycles on an Apple Macintosh microcomputer are outlined.