The walls of guard cells have many specialized features. Guard cells are present in the leaves of bryophytes, ferns, and almost all vascular plants. However, they exhibit considerable morphological diversities. There are two types of guard cells: the first type is found in a few monocots, such as palms and corn, and the other is found in most dicots, many monocots, mosses, ferns, and gymnosperms. In corns, guard cells have a characteristic dumbbell shape with bulbous ends. Most dicot and monocot species have kidney-shaped guard cells that have an elliptical contour with a pore at its center. Although subsidiary cells are common in species with kidney-shaped stomata, they are almost always absent in most of the other plants. In this study, there were many different stomatal features that were associated with kidney-shaped guard cells, but not dumbbell shaped guard cells, which are present in most grasses, such as cereals. Each plant investigated exhibited different characteristic features and most of these plants had kidney-shaped guard cells. However, the guard cells of Chamaesyce supina Mold, were often more rectangular than kidney-shaped. In contrast, Sedum sarmentosum guard cells were of the sink ensiform type and in Trifolium repens, the guard cells exhibited a more rhombic shape. Therefore, kidney-shaped guard cells could be divided into a number of subtypes that need to be investigated further.

Stress induced cardiomyopathy is characterized by transient systolic dysfunction of the apical segment of the left ventricle, in the absence of obstructive coronary artery disease. The clinical presentation of stress induced cardiomyopathy is similar to that of an acute myocardial infarction. Onset of stress induced cardiomyopathy is frequently triggered by intense emotional or physical stress. Hypoglycemia is one type of physical stress that causes stress induced cardiomyopathy. We report on a case of this syndrome associated with hypoglycemia.

Effects of dimethipin on α-amylase activity of barley seeds were investigated. In the treatments of 1 μM and 10 μM dimethipin, the indexes of germination were reduced to 17% and 24 % respectively. After seed germination, dimethipin was added to germinated seedlings and then the seedlings were kept to measure seedling length under illumination for 7 days. In control, the length of seedling was 5.7 cm, but in the treatments of 1 μM dimethipin and 10 μM dimethipin, seedling lengths were 5.5 cm and 1.2 cm respectively. In the relationship between dimethipin concentrations and α-amylase activities, there was a linear curve. The more dimethipin was added to the seeds, the more α-amylase activities were inhibited. In the treatments of 1 μM dimethipin and 10 μM dimethipin, α-amylase activities were reduced to 33% and 71% respectively. Dimethipin also inhibited α-amylase activities increased by gibberellin and the content of soluble protein. Therefore, it could be suggested that dimethipin might inhibit directly the activities of hydrolysis enzymes including α-amylase or the expression of α-amylase genes as germination and seedling growth were severely disturbed.

Three-week old Commelina communis was transferred and grown in Hoagland solution containing 100μM Cd2+, 100μM Cd2++100μM kinetin, 100μM Cd2++100μM zeatin and 100μM Cd2++200μM zeatin for 7 days, and then a number of physiological activities were investigated. In control, the length of the stem of plants was increased to 4.7cm, but in Cd2+, Cd2++kinetin, Cd2++100μM zeatin and Cd2++200μM zeatin treatments, the growth of plants were increased to 1.5cm, 2.1cm, 3.9cm and 4.3cm, respectively. In the treatments of Cd2+, Cd2+ +kinetin, Cd2++100μM zeatin and Cd2++200μM zeatin, total chlorophyll contents were reduced to 26%, 24%, 15% and 3%, respectively, on the contrast to the control. In chlorophyll fluorescence experiments, Fv/Fm ratios were also reduced to 44%, 21%, 17% and 5% in the light intensity of 2100μmole E m-2s-1 by Cd2+, Cd2++ kinetin, Cd2++100μM zeatin and Cd2++200μM zeatin treatments on the contrast to the control. Water stresses were increased to 2.6, 1.7 and 1.2 times by Cd2+, Cd2++kinetin and Cd2++100μM zeatin. On the other hand, combination of Cd2++200μM zeatin reduced water stress to 0.12%. In Cd2+ accumulation experiments Cd2+ transports were inhibited to 33%, 48% and 70% by Cd2++kinetin, Cd2++100μM zeatin and Cd2++200μM zeatin. Therefore, it could be concluded that zeatin clearly reduced the toxicities of Cd2+ by reducing the absorption of Cd2+.

3-weeks old Commelina was transferred to and grown in Hoagland solution (Control, 100μM Cd2+, 100μM Cd2++100μM IAA, 100μM Cd2++100μM IAA+2 mM sucrose) for 3 weeks and then the effects of indole acetic acid (IAA) on the accumulation of Cd2+ and growth of Cd2+-treated Commelina were investigated. In the treatment of Cd2+, Cd2+ was uptaked to 1.74, and 51.36 μg/g frwt. at the first week, but for three weeks, 0.51 and 34.53 μg/g frwt. in leaf and stem respectively. When IAA was treated along with Cd2+, Cd2+ was uptaked to 0.18 and 8.63 μg/g frwt. at the first week, and for the incubation of 3 weeks, 0.51 and 45.0 μg/g frwt. in leaf and stem. In case of Cd2++IAA+sucrose, Cd2+ was uptaked to 1.45 and 18.33 μg/g frwt. at the first week, but for 3 weeks, 0.51 and 25.45 μg/g frwt. in leaf and stem. Likewise Cd2+ uptake, the growth was also affected by Cd2+ and IAA. During the incubation of 3 weeks, Cd2+ reduced the stem growth about 8% in all weeks, but the treatment of IAA recovered the inhibition of stem growth caused by Cd2+ to the degree of the control Therefore, it could be concluded that IAA altered the pattern of Cd2+ uptake and the growth which were supposed to change Cd2+ toxicity.

The mechanism of stomatal closing in response to O_3 was indirectly investigated by using H_2O_2 which is the intermediate product of O_3 metabolites. Stomata in epidermal strips close in response to H_2O_2. The effect of H_2O_2 on stomatal closing was dependent on the concentration of H_2O_2. 10 ppm H_2O_2 showed a clear effect on stomatal closing and 1000 ppm H_2O_2 induced complete stomatal closing after the treatment of 3 hours. Stomatal closing by H_2O_2 in intact leaf was also observed by measuring the diffusion resistance with porometer. It was found that the stomatal closing by H_2O_2 was not mediated by Ca^2+, and that was a different result observed in stomatal closing by water stress. Reversely, Ca^2+, showed a great inhibition on stomatal closing. The leakage of K^+ in epidermal strips was doubled in response to H_2O_2 when it was campared to the control. 10 ppm H_2O_2 decreased photosynthetic activity. Fv/Fm representing the activity of Photosystem Ⅱ was reduced about 4 % in 10 ppm H_20_2 and 8 % in 100 ppm H_2O_2 in the treatment of 1.5 hour. However, stomatal closing by 10 ppm H_2O_2 was reduced about 56 %. Accordingly, it can be suggetsted that stomatal closing by H_2O_2 is related with the decrease of photosynthetic activity, but it was chiefly induced by the change of the membrane permeability.

ABA and SA showed different effect on stomatal closing on same condition. The addition of 1 mM salicylic acid to fully opened stomata resulted in a significant reductionn of 22 % in stomatal aperture. However, 1 mM ABA reduced 73 % of stomatal aperture. The light absorption spectra of the salicylic acid solution showed that SA was degraded within 1 hour. Therefore, SA solution was resupplied to the detached epidermis every 30 min. during incubation and it was found that even at 10 μM SA induced stomatal closing significantly. Its effect was also greatly pH dependent. The reduction of stomatal aperture caused by 1 mM SA was most effective at lower pH (pH 7.2, 5 %; pH 6.2, 40 %; pH 5.2, 78 %). Therefore, if SA was properly treated to the epidermal strips in the medium, the effects of SA on stomatal closing were similar with those of ABA.