Colorado potato beetle larvae on potato plants expressing a locust proteinase inhibitor.

The natural defence system of plants often involves inhibitors of digestive enzymes of their pests. Modem and environmental-friendly methods try to increase this plant resistance by expressing heterologous protease inhibitors in crops. Here we report the effects of expressing a gene from desert locust (Schistocerca gregaria) encoding two serine protease inhibitors in potato on Colorado potato beetle (Leptinotarsa decemlineata) larvae. The gene encoding both peptides on a single chain was used for Agrobacterium-mediated transformation of potato plants. The presence of the active inhibitor protein in the leaves was verified. The feeding bioassays in the laboratory showed that despite the low level of the peptide in leaves, CPB larvae on transgenic plants have grown slightly but significantly more slowly than those on control potato plants. The results support the notion that expression of multifunctional proteinase inhibitors of insect origin in plants might be a good strategy to improve insect resistance.

Primary structure and specificity of a serine proteinase inhibitor from paprika (Capsicum annuum) seeds.

Several fractions demonstrating trypsin inhibitory activity were isolated from the seeds of the paprika plant (Capsicum annuum). One of the inhibitors, PSI-1.1, was purified to homogeneity and characterised. The mature form of PSI-1.1 has a molecular mass of 6053 Da and consists of 55 amino acids in a sequence showing over 80% identity with members of the inhibitors of potato-2 family. PSI-1.1 is a potent inhibitor of trypsin (Ki = 4.8 x 10(-10) M) and a somewhat weaker inhibitor of chymotrypsin (Ki = 4.7 x 10(-8) M) and pronase E (Ki = 5.9 x 10(-8) M). PSI-1.1 is resistant to heat up to 85 degrees C, to acidic conditions (down to pH 2.0) and to pepsin digestion, presumably due to its four disulfide bridges.

Taurine levels in discrete brain nuclei of rats.

Concentrations of taurine have been measured in 44 microdissected rat brain nuclei or areas. Taurine is ubiquitously present and distributed unevenly in the rat brain: the ratio of the highest (pyriform cortex) to lowest (midbrain reticular formation) concentrations is 4.7:1. High taurine levels were found in cerebral cortical areas, caudate-putamen, cerebellum, median eminence, and supraoptic nucleus. Acute pain stress reduced taurine levels in the hypothalamus and the lower brainstem nuclei but not in cortical areas. Increased locomotor and behavioral activities following a high dose of amphetamine elevated taurine concentrations significantly in the substantia nigra and locus ceruleus.

Concentrations of GABA and glycine in discrete brain nuclei. Stress-induced changes in the levels of inhibitory amino acids.

Concentrations of gamma-aminobutyric acid (GABA), glycine and serine have been measured in 44 microdissected areas of the brain of the rat. All three amino acids were ubiquitously present and distributed unevenly in the brain. Very high levels of GABA were found in the anterior hypothalamic and medial preoptic nuclei and the substantia nigra; high levels were found in the interpeduncular and red nuclei in the mesencephalon and in several hypothalamic nuclei. Glycine was distributed fairly uniformly with large concentrations in certain lower brainstem nuclei. In these areas, the concentrations of glycine exceeded those of serine, while the serine-glycine ratio was 4.5:1 in the caudate nucleus, 4:1 in the cerebellum and 2.5:1 in the cerebral cortical areas. Acute stress induced with formalin (pain) resulted in a significant depletion of levels of GABA in the hypothalamus and the lower brainstem but not in the cortical areas. In the same animals, concentrations of glycine doubled in the cerebral cortex and remained unchanged elsewhere in the brain. Increased motor and behavioral activity after the acute administration of a large dose of amphetamine were associated with a 2-5-fold increase in the levels of glycine in brain, and markedly elevated the concentrations of GABA in the major biogenic amine-containing cell groups only (substantia nigra, locus coeruleus and dorsal raphe).

Distribution and stress-induced increase of glutamate and aspartate levels in discrete brain nuclei of rats.

Concentrations of glutamate and aspartate have been measured in 45 microdissected brain areas and nuclei in rat. Both amino acids are ubiquitously present and distributed unevenly in the central nervous system. Very high glutamate levels were found in the cerebellum and the insular cortex, high levels in neocortical and limbic cortical areas, and in the nuclei of the medial hypothalamus. Aspartate is distributed rather uniformly with the highest concentration in the hypothalamic arcuate nucleus and the lowest in the midbrain central gray matter and the cerebellum. Acute formalin (pain) stress elevated glutamate and aspartate levels in the cortical areas and substantia nigra significantly, but had minor or no effects on other brain nuclei. Increased locomotor and behavioral activities due to a high dose of amphetamine resulted in a 2-5-fold increase of glutamate and aspartate concentrations, particularly in the biogenic amine-containing brain nuclei.