The N-terminal P1 proteinase of potato virus Y (ordinary strain group isolate PVY-O) was expressed in E. coli. Antiserum was raised against the expressed protein and used to detect the viral proteins in infected tobacco leaf tissue by Western blotting and by electron microscopy with immunogold labelling. In the immunogold localization studies P1 protein was detected in association with the cytoplasmic inclusion bodies characteristic of PVY infections and in the cytoplasm of the infected plant cells. No significant P1 antibody binding with other plant cell organelles, or with the cell wall and plasmodesmata, was detected by immunogold labelling.

Transgenic mice overexpressing ornithine decarboxylase (ODC) were recently generated (Halmekytö et al.: Biochem Biophys Res Commun 180:262-267, 1991). The dramatic ODC overexpression resulted in a very high accumulation of the polyamine putrescine in the brain. As elevated polyamine levels in the brain are believed to be associated with neuronal damage, we studied whether enhanced putrescine accumulation in the brain of these mice affects the expression of neurotrophins and their high affinity receptors. Northern blot analysis indicated that mRNA levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF) and neurotrophin-3 (NT-3) were significantly elevated about 1.5-fold in the hippocampus of ODC transgenic mice as compared with control animals. The levels of BDNF, NGF and NT-3 mRNA were also elevated in the kidneys of the transgenic mice. In eight other tissues examined there were no significant differences. The expression pattern of BDNF mRNA and of trkB and trkC (high affinity receptors for BDNF and NT-3 respectively) immunoreactivity in the hippocampal formation did not reveal significant differences. The induction of the expression of neurotrophins could belong to neuroprotective measures triggered by ODC overexpression.

Transgenic mice overexpressing ornithine decarboxylase (ODC) were recently generated (Halmekytö et al.: Biochem Biophys Res Commun 180:262–267, 1991). The dramatic ODC overexpression resulted in a very high accumulation of the polyamine putrescine in the brain. As elevated polyamine levels in the brain are believed to be associated with neuronal damage, we studied whether enhanced putrescine accumulation in the brain of these mice affects the expression of neurotrophins and their high affinity receptors. Northern blot analysis indicated that mRNA levels of brain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF) and neurotrophin‐3 (NT‐3) were significantly elevated about 1.5‐fold in the hippocampus of ODC transgenic mice as compared with control animals. The levels of BDNF, NGF and NT‐3 mRNA were also elevated in the kidneys of the transgenic mice. In eight other tissues examined there were no significant differences. The expression pattern of BDNF mRNA and of trkB and trkC (high affinity receptors for BDNF and NT‐3 respectively) immunoreactivity in the hippocampal formation did not reveal significant differences. The induction of the expression of neurotrophins could belong to neuroprotective measures triggered by ODC overexpression. © 1996 Wiley‐Liss, Inc.