Fungus gnat head. [photo: R. Gardiner]
Some members of the family Sciaridae are important pests of various commercial crops such as mushrooms, greenhouse flowers and vegetables. Sciarid flies are one of the several groups of insects that consume fungi as part of or all of their diets and have been suspected of causing damage to crops either directly or indirectly. Fungi are usually present in the environment around the plant roots where the sciarid larvae live. Some of these fungi are important pathogens, such as species of the Pythiaceae. I have shown that in the case of Bradysia impatiens Pythium species can serve as the sole food source for the gnat larvae. The fungal mycelium was consumed by the gnat larvae but the oospores and zoospoore cysts passed through the digestive tract and remained viable. This showed that in regard to Pythium fungus gnats could be a vector for the disease. Transmission either internal or external by the adults was not observed.
Caterpillar Skeletal Muscle. [photo: R. Gardiner]
The membrane that surrounds cells is impermeable to most hydrophilic solutes the cell requires and to many of the waste products it must get rid of. To solve this problem the membrane contains proteins, transporters, which mediate the transport of substrates through the membrane. It has been estimated that between 5 and 15% of all proteins are membrane transport proteins. Glutamate functions as a neurotransmitter in a wide variety of animals, and in mammals it is the predominat excitatory neurotrasmitter in the central nervous system. It has to be removed from the extracellular fluid since it is toxic at high concentrations. This is accomplished by sodium and potassium coupled transporters. We have localizeded the transporter in the cabbage looper, Trichoplusia ni, to both neuromuscular junctions and the ganglia of the central nervous system. Electron microscopy has shown that the plasama membrane of glial cells, but not that of the neurons is labelled.