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  • cambial resistance  (1)
  • spontaneously hypertensive rat  (1)
  • water stress  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Cerebral Blood Flow Threshold and Regional Heterogeneity of Heat Shock Protein 72 Induction Following Transient Forebrain Ischemia in Rats (1999)
    Springer
    Neurochemical research 24 (1999), S. 679-683 
    Details
    ISSN: 1573-6903
    Keywords: Hippocampus ; striatum ; spontaneously hypertensive rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Heat shock proteins (HSPs) induced by brain ischemia may play an important role in neuroprotection from neuronal degeneration. In this study, we examined the cerebral blood flow (CBF) threshold to produce regional differences in HSP72 induction after transient forebrain ischemia in spontaneously hypertensive rats (SHRs). Female SHRs were subjected to 20 min of cerebral ischemia induced by bilateral carotid artery occlusion. The CBF was measured by laser Doppler flowmetry. At forty-eight hours after cerebral ischemia and reperfusion, the rats were decapitated and the brains were removed. Specific areas (hippocampal CA1, CA2-3, dentate gyrus, dorsolateral and ventromedial striatum, and parietal cortex) were thereafter dissected from the brain. The amounts of HSP72 in these samples were determined using Western blot analysis. In the hippocampus, HSP72 was induced when the CBF decreased to less than 18–25% of the resting level. The mean values of HSP72 produced in the CA1 area, CA2-3 area, and the dentate gyrus following ischemia and reperfusion treatment were 4.44 ± 1.43 (±SD) ng/μg prtein, 3.51 ± 0.72 ng/μg protein and 3.77 ± 1.05 ng/μg protein, respectively. In the parietal cortex, the amount of HSP72 induction was less pronounced (2.55 ± 0.40 ng/μg protein), while HSP72 was hardly detected at all in the striatum, even under conditions of very severe CBF reduction and reperfusion. We demonstrated the existence of both a CBF threshold (i.e., approximately 20% of the resting level) for HSP72 induction and regional heterogeneity for the induction of HSP72 protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021056510049
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  • 2
    Electronic Resource
    Electronic Resource
    Water relations of Yezo spruce and Todo fir in declined stands of boreal Forest in Hokkaido, Japan (1997)
    Springer
    Journal of forest research 2 (1997), S. 79-84 
    Details
    ISSN: 1610-7403
    Keywords: Abies sachalinensis ; forest decline ; Picea jezoensis ; typhoon damage ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Recently, symptoms of decline have been widely observed in Yezo spruce (Picea jezoensis) and Todo fir (Abies sachalinensis) in Hokkaido. In order to clarify the mechanism of decline, the water status of Yezo spruce and Todo fir trees in the Tokyo University Forest in Hokkaido were investigated. The decline is observed mainly in stands damaged by Typhoon XV of 1981 (D-stands), but is not observed in undamaged stands (C-stands). Sampled trees in both types of stands were selected, the severity of their decline estimated, diurnal water potentials measured and water relation parameters such as water potential at turgor-loss point ( $$\Psi _{w(tlp)} $$ ) and osmotic potential at full saturation ( $$\Psi _{s(sat)} $$ ) were estimated by pressure-volume analysis. The diurnal trends of leaf water potential and midday water potential ( $$\Psi _{w(min)} $$ ) of the sample trees were clearly different between the D-stands and the C-stand. Water stress in trees was much more severe in the D-stands than in the C-stand. $$\Psi _{w(tlp)} $$ and $$\Psi _{s(sat)} $$ of the declining trees were lower in the D-stands than in the C-stand. However, $$\Psi _{w(tlp)} $$ and $$\Psi _{s(sat)} $$ were not significantly different between declining trees and healthy-looking trees in D-stands. It was concluded that stand-level water stress, induced by the destruction of the canopy by the typhoon, was associated with the decline symptoms. The measurement of water relation parameters proved to be useful for diagnosis and prediction of decline at a stand level in this area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02348473
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  • 3
    Electronic Resource
    Electronic Resource
    Physiological process of the symptom development and resistance mechanism in pine wilt disease (1997)
    Springer
    Journal of forest research 2 (1997), S. 171-181 
    Details
    ISSN: 1610-7403
    Keywords: Bursaphelenchus mucronatus ; Bursaphelenchus xylophilus ; cambial resistance ; Pinus densiflora ; Pinus thunbergii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pathophysiological changes during the symptom development of pine wilt disease are reconsidered from recent investigations. The symptom development is divided into two stages: the early and the advanced stages. In the early stage, small number of nematodes migrate in cortex, then in xylem of the stem, and induce denaturation and necrosis of parenchyma cells. These changes in parenchyma are regarded as defense reactions of pines which result in terpene synthesis in xylem cells and embolism in tracheids. Such changes in the early stage can be induced in both susceptible and resistant pine species by either virulent or avirulent isolates of pinewood nematode (Bursaphelenchus xylophilus), or byB. mucronatus. No change occur in physiological status of leaves, and nematode reproduction is suppressed during this stage. Pine trees can survive if symptom does not progress from this stage. The symptoms of the advanced stage usually occur only in susceptible pines infected by virulent nematode isolates. At the beginning of the advanced stage, enhanced ethylene production by stem which coincides with cambial destruction occurs, and results in embolism of the outermost xylem in the portion. The embolism causes decrease in leaf water potential and cessation of photosynthesis. After cessation of photosynthesis, symptoms develop drastically with a burst of nematode population. There seems to be some unknown mechanism which suppress nematode reproduction and invasion to the cambial zone. This mechanism is thought to be photosynthesis-dependent, so that in photosynthesis-decrased conditions, even avirulent nematodes can multiply and invade cambium to induce tree death. Water stress in hot and dry summer should accelerates symptom development from the early to the advanced stage through such decrease of photosynthesis-dependent “cambial resistance”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02348216
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    Paper (German National Licenses)
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