The relationship between absorption of sulfur dioxide (SO2) and inhibition of photosynthesis in several plants

Photosynthetic rate, transpiration rate and SO₂ absorption rate were simultaneously measured under exposure to SO₂ (0.1–1.0 μl l ^?1) for 5 or 8 hr in six species belonging to C₄ or C₃ plants (Zea mays, Sorghum vulgare, Amaranthus tricolor, Oryza sativa, Avena sativa andHelianthus annuus). Distinct interspecific differences were found as to the extent of inhibition of photosynthetic rate. Calculation of diffusive resistance to H₂O(r) and SO₂(r′) showed that the ratio of r′/r was 1.9 irrespective of species and coincided well with the theoretical value based on molecular diffusion. Thus it was made clear that the absorption of SO₂ was dependent upon the gas exchange capacity of leaf blade. Using the ratio of r′/r the rate of SO₂ absorption could be calculated from transpiration rate and was compared with the inhibition rate of photosynthesis. In three C₄ species, the inhibition of photosynthesis increased linearly with the amount of SO₂ absorbed during a 5-hour period. The pattern of inhibition of photosynthesis inA. sativa andH. annuus among C₃ species was similar to that of C₄ species until the amount of SO₂ absorbed reached 60 mg-SO₂ m^?2 above which the inhibition abruptly increased. The inhibition of photosynthesis inO. sativa was exceptionally severe even with only a small amount of SO₂ absorbed.     

Chemiluminescence probe with Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one, for estimating the ability of human granulocytes to generate O2-

The Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one (CLA), in Hanks' balanced salt solution, emitted a weak luminescence which was not affected by superoxide dismutase or catalase and was not augmented by resting human granulocytes. In contrast, activated granulocytes caused a dramatic increase in the luminescence of CLA. The light emission by CLA in the presence of activated granulocytes was inhibited by superoxide dismutase, but not by catalase or benzoate. Azide at 0.5 mM did not inhibit light emission significantly. These results indicate that O2-, rather than H2O2, HO., singlet oxygen, or HOCl, was the agent responsible for eliciting the chemiluminescence of CLA. Moreover, the intensity of light emission by CLA correlated with the rate of production of O2- either by activated neutrophils or by the xanthine oxidase reaction.     

Identity of aliphatic L- -hydroxyacid oxidase and glycolate oxidase from rat livers

l-α-Hydroxyacid oxidase and glycolate oxidase have been partially purified from rat livers and found to be identical, judging by substrate specificities, K_m values for certain substrates and coenzyme (FMN), activation energy, inhibition rates by various reagents and pH optimum. K_m values are as follows; glycolate, 2.4 × 10^?4m; l-α-hydroxyisocaproate, 1.26 × 10^?3; glyoxylate, 1.41 × 10^?4m; and FMN, 1.13 × 10^?6m. K_m values for glycolate and FMN are one-tenth and one-twentieth the literature values for hepatic glycolate oxidase. Sucrose density gradient centrifugation establishes that this enzyme is located in hepatic peroxisomes.     

Inhibition of rotavirus and enterovirus infections by tea extracts.

Epigallocatechin gallate from green tea and theaflavin digallate from black tea inhibited infections of cultured rhesus monkey kidney MA 104 cells with rotaviruses and enteroviruses. Their antiviral effects were maximally induced when directly added to virus, and their pre- and post-treatment of the cells produced much weak antiviral activity. Antiviral activity of the extracts therefore seems to be attributable to interference with virus adsorption.     

Production and identification of bityrosine in horseradish peroxidase-H2O2-tyrosine system

Production of bityrosine (2,2'-dihydroxy-5,5'-bis (beta-carboxy-beta-aminoetyl)-diphenyl) was established in horseradish peroxidase-H2O2-tyrosine system at pH 9.2 by mass and NMR spectrometries.     

Hydrolytic enzyme activities in germinating spores ofAdiantum capillus-veneris L.

Changes in hydrolytic enzyme activities were investigated during spore germination ofAdiantum capillus-veneris L. The spores were incubated for 3 days in the dark at 25 C for imbibition, and then germination of the spores was induced by continuous irradiation with red light. At day 2 after onset of the red light irradiation, rhizoids appeared out of spore coats and protonemal cells became visible on the following day. Lipase occurred in dry spores and its activity decreased during 3 days of dark incubation. The activity started to increase when the spore germination was induced by red light irradiation. On the other hand, amylolytic and aminopeptidase activities which were also detected in dry spores decreased continuously during the dark incubation and following the germination process. RNase activity also decreased during 3 days of dark incubation but the activity was retained thereafter at a constant level with or without red light irradiation. Developmental patterns of these hydrolytic enzymes were classified into two groups: One decreased during imbibition and dark incubation but increased after red light irradiation and the other continuously decreased during dark incubation and germination. These results are discussed in relation to compositional changes of cell constitutions such as lipid, sugars, proteins and amino acids during spore germination.