Needle traits of an evergreen, coniferous shrub growing at wind-exposed and protected sites in a mountain region: does Pinus pumila produce needles with greater mass per area under wind-stress conditions?

Snow depth is one of the most important determinants of vegetation, especially in mountainous regions. In such regions, snow depth tends to be low at wind-exposed sites such as ridges, where stand height and productivity are limited by stressful environmental conditions during winter. Siberian dwarf pine (Pinus pumila Regel) is a dominant species in mountainous regions of Japan. We hypothesized that P. pumila produces needles with greater mass per area at wind-exposed sites than at wind-protected sites because it invests more nitrogen (N) in cell walls at the expense of N investment in the photosynthetic apparatus, resulting in increased photosynthetic N use efficiency (PNUE). Contrary to our hypothesis, plants at wind-exposed site invested less resources in needles, as exhibited by lower biomass, N, Rubisco and cell wall mass per unit area, and had higher photosynthetic capacity, higher PNUE and shorter needle life-span than plants at a wind-protected site. N partitioning was not significantly different between sites. These results suggest that P. pumila at wind-exposed sites produces needles at low cost with high productivity to compensate for a short leaf life-span, which may be imposed by wind stress when needles appear above the snow surface in winter.

Acid fog damage of beech at Hinokiboramaru-Tanzawa, Japan.

Decline of Japanese beech forest has been obvious at the Tanzawa Mountains near Tokyo. Observations on fog, precipitation and stem flow were performed during June-October, 1994 on both, NE (with healthy beech) and S-SE (with unhealthy beech) slopes, collecting samples biweekly. Chemical species were determined by ion-chromatography and pH meter. The results show that the pH of the precipitation was between 4.4-5.2, with no clear differences in the concentrations of chemical species between both sites and seasons. The pH of the fog water was high from May to the middle of August and lower from mid-August to October at both sites. The concentrations of most chemical species were higher in fog samples than precipitation samples. The concentrations of potassium and magnesium ions in the stem flow of an unhealthy tree on the S-SE slope were higher than those on the NE slope. In June-October, 1995, ten pairs of event fog water samples were obtained with indicating that the pH was below 4.0 for five pairs of event fog water samples. Lower pH value was obtained on the S-SE slope than on the NE slope in every event. Concentrations of most chemical species were always higher in the fog samples from the S-SE slope than those from the NE slope. The equivalent ratio of NO3-/nssSO4(2-) was higher in the fogs of higher acidity. From the result of atmospheric current analysis using a model, it was suggested that the polluted air over the Tokyo Metropolitan Area affected the fog acidity directly and also indirectly, according to the pressure patterns.

Beta2-adrenoceptors on the glial cells mediate the induction of interleukin-1beta mRNA in the rat brain.

Interleukin-1beta mRNA was induced by i.c.v. injection of the beta-adrenoceptor agonist isoproterenol. Lower doses of procaterol, a beta2-adrenoceptor agonist showed stronger induction of the mRNA than isoproterenol. These inductions were primarily observed in the glial cells. On the other hand, the beta1-adrenoceptor agonist dobutamine induced expression of this mRNA only in the meninges. These results suggest the existence of a system for regulation of interleukin-1beta gene expression via beta2-adrenoceptors in the brain parenchyma.

Intracerebroventricular injection of isoproterenol produces its analgesic effect through interleukin-1beta production.

The effects of isoproterenol, a beta-adrenoceptor agonist, on the production of interleukin-1beta in the brain and on mechanical nociception were examined in rats. Intracerebroventricular (i.c.v.) injection of isoproterenol at the dose of 3 microg/rat markedly induced interleukin-1beta mRNA in the molecular layer of the hippocampus, medial preoptic area, paraventricular thalamic nucleus, paraventricular hypothalamic nucleus, ventromedial hypothalamic nucleus, dorsomedial hypothalamic nucleus and central gray 1 h after injection. In these regions, interleukin-1beta mRNA was expressed mainly in the glial cells. The thresholds to the mechanical stimulation to the hind paw were elevated by i.c.v. administration of isoproterenol (1 to 10 microg/rat). When isoproterenol was given at the dose of 3 microg/rat, the analgesic effect showed two peaks. The first peak was observed at 60 min after injection and the second was observed at 180 min. The second phase of analgesia was antagonized by coadministration of interleukin-1 receptor antagonist. These results suggest that isoproterenol produces an analgesic effect, at least in part, through the induction of interleukin-1beta expression in the brain.

Induction of interleukin-1 beta mRNA in the hypothalamus following subcutaneous injections of formalin into the rat hind paws.

The induction of interleukin-1 beta (IL-1 beta) mRNA in the rat brain following subcutaneous injection of formalin into the hind paws was investigated by in situ hydridization. IL-1 beta mRNA was markedly induced in the hypothalamus after the injection of formalin into both hind paws. On the other hand, IL-1 beta mRNA was scarcely observed in the hypothalamus of saline-injected control rats. The type of cells expressing IL-1 beta mRNA was likely glia because their nuclei were densely stained by Cresyl violet and were relatively small. The present results suggest that IL-1 beta mRNA is induced in the glial cells of the hypothalamus by persistent pain which is caused by formalin injection.

Central action of bradykinin (I). Electroencephalogram of bradykinin and its degradation system in rat brain.

Both in vivo and in vitro experiments were performed to elucidate the relationship between the action of bradykinin (BK) and the possibility of release of pharmacologically active fragments from BK in the rat brain. In in vivo experiments, the activities of electroencephalogram (EEG) increased immediately after the intracerebral administration of 5 nmole BK. The effect was prolonged by intracerebral pretreatment of o-phenanthroline which inhibits plasma kininases. In vitro experiments, o-phenanthroline inhibited partially purified enzyme of rat brain which released fragments of BK possessing phenylalanine, serine, proline and/or arginine as N-terminal amino acids. Only arginine and minute amounts of phenylalanine were observed after the incubation with o-phenanthroline. The evidence suggests that the inhibition of the enzyme by o-phenanthroline resulted in a prolongation of the excited phase produced by BK on the EEG and on behavior. Supporting evidence indicates that Ser-Pro containing fragments derived from BK are concerned with the sedative phase of BK which was observed after the excitative stage.