Water relations of host trees and resistance to the phloem-boring beetle Phoracantha semipunctata F. (Coleoptera: Cerambycidae).

Environmental stresses, particularly water deficit, predispose eucalypt trees to attack by the eucalyptus longhorned borer, Phoracantha semipunctata F. (Coleoptera: Cerambycidae). Our experiments with potted eucalypts revealed that reduced tree water potential was associated with lower resistance to colonization by neonate P.

Neural cell adhesion molecules influence second messenger systems.

We have investigated the influence of the neural cell adhesion molecules L1 and N-CAM on second messenger systems using a PC12 rat pheochromocytoma cell line as a model and triggering cell surface receptors by specific antibody binding. Antibodies directed against L1 and N-CAM, but not against other cell surface components, reduce intracellular levels of the inositol phosphates IP2 and IP3, while intracellular levels of cAMP are unaffected. Antibodies against L1 and N-CAM also reduce intracellular pH and increase intracellular Ca2+ by opening Ca2+ channels in a pertussis toxin-inhibitable manner, suggesting the involvement of a G protein in the signal transduction process.