Stress-induced growth

Under certain conditions, embrittlement can be enhanced by the presence of the helium bubbles (helium embrittlement). The accepted view is that this embrittlement is the result of stress-induced growth of helium gas bubbles at the grain boundaries. The bubbles eventually link up and cause intergranular failure. 

Ludlow, M.M. Powles, S.B. (1988). Effects of photoinhibition induced by water stress of growth and yield of grain sorghum. In Ecology of Photosynthesis in Sun and Shade, ed. J.R. Evans, S. von Caemmerer and W.W. Adams III, pp. 179-94. Melbourne CSIRO. 

In a previous work, we found an increased pectinase production under extreme acidic pH conditions. Since very acidic pH induced stress conditions in the cell it is interesting to evaluate the response of different Aspergillus strains toward stress induced by the pH of culture medium. In our laboratory we have studied the effect of extreme acidic pH on growth and secretion of pectinases by a vtrild white strain of Aspergillus and by Aspergillus niger N-402. 

The reported (14) mechanisms of action of allelochemlcals Include effects on root ultrastructure and subsequent Inhibition of Ion absorption and water uptake, effects on hormone-induced growth, alteration of membrane permeability, changes In lipid and organic acid metabolism, inhibition of protein synthesis and alteration of enzyme activity, and effects on stomatal opening and on photosynthesis. Reduced leaf water potential Is one result of treatment with ferulic and p-coumaric acids (15). Colton and Einhellig (16) found that aqueous extracts of velvetleaf (Abutllon theophrastl Medic.) Increased diffusive resistance In soybean fGlycine max. (L.) Merr.] leaves, probably as a result of stomatal closure. In addition, there was evidence of water stress and reduced quantities of chlorophyll In Inhibited plants. 

Szechynska-Hebda M, Skrzypek E, D browska G, Biesaga-KoScielniak J, Filek M, W dzony M (2007) The role of oxidative stress induced by growth regulators in the regeneration process of wheat. Acta Physiol Plant 29 327-337... 

Exposure of the SECs to pathogens or cytokines produced by other cells during stress induces activation of the SECs and subsequent production of cytokines, eicosanoids, and/or adhesion molecules. For instance, after activation with EPS, a main component of the walls of gramnegative bacteria and a major inducer of inflammation and non-specific immune functions [20], SECs produce a number of pro- and anti-inflammatory cytokines. Pro-inflammatory cytokines shown to be produced were tumour necrosis factor alpha (TNFa) [26] interleukin-1 alpha/beta(IL-lo/p) [27] the major inducer of acute phase proteins interleukin-6 (IL-6) [28] and the neutrophil chemo-attractant interleukin-8 (IL-8) [29]. Anti-inflammatory cytokines shown to be produced were interleukin-10 (IL-10) [27] and hepatocyte growth factor (HGF) [30]. 

Most plants suffer damage, both physiological and biochemical by exposure to temperatures higher or lower than optimal for growth [99]. The results of these injuries, which are reflected in most metabolic processes may be a reduced growth capacity of the crops and therefore lower commercial yield [100]. It has been demontrated that thermal stress induces the production of phenolic compounds [3,4,101]. 

For the c-BN formation a stress threshold was observed in the deposited layers. The h-BN intermediate layer shows a preferred orientation, where the c-axis of the h-BN is parallel to the substrate. Both effects are explained by the compressive biaxial stress induced by the ion bombardment. The mechanism for the conversion of h-BN into c-BN is explained by rather high temperatures originated during thermal spikes (direct h-BN —> c-BN transformation). The stress caused by the bombardment with high energetic ions is considered to be a reason for the growth of the c-BN crystals [190, 191]. A stress within the layer of up to 10 GPa has been observed. This biaxial stress causes a hydrostatic pressure up to the values usual in HP-HT synthesis. 

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