Partial characterization of farnesyl and geranylgeranyl diphosphatases induced in rice seedlings by UV-C irradiation

This study reports the identification and characterization of allyl diphosphatases (EC 3.1.7.1) in plants by using rice seedlings. Two distinct Mg(2+)-independent allyl diphosphatases, which convert farnesyl diphosphate (FDP) and geranylgeranyl diphosphate (GGDP) into farnesol and geranylgeraniol, respectively, were induced in rice seedlings irradiated with UV-C. Farnesyl diphosphatase (FDPase) and geranylgeranyl diphosphatase (GGDPase) are located in the microsomal fraction. The relative specific activity of FDPase was much higher than the specific activity of GGDPase. FDPase activity was inhibited by GGDP (50% inhibition at 5 microM) and geranyl diphosphate (50% inhibition at 100 microM). In contrast, GGDPase activity was inhibited 50% by 50 microM isopentenyl diphosphate or 100 microM FDP. The optimal pH for FDPase was 6.3 and for GGDPase was 7.9.

In vivo antioxidant effect of green tea

OBJECTIVE

The object of this study was to investigate the in vivo antioxidant effect of green tea and dosage effect of green tea on antioxidant effect.

DESIGN

We tested 10 healthy subjects (aged 23-25 y, five women and five men) with overnight fasting. The total antioxidant capacity of plasma was measured at baseline and 60 min and 120 min after ingestion of 150 ml green tea. Green tea was prepared by infusing 2.5 g of dried green tea leaves for 2 min at 80 degrees C in 150 ml of water. In the second week, they took 300 ml of tea (5.0 g of green tea leaves) and, in the third week, 450 ml of tea (7.5 g of green tea leaves). The total antioxidant capacities of plasma were determined with a Total Antioxidant Kit (Randox Laboratories Ltd, UK) using a Cobas Mira analyser (Roche Diagnostic Systems Inc., Switzerland). The mean intra-assay coefficient of variation was 1.2%.

RESULTS

The total antioxidant capacity of plasma increased by 1.1% at 60 min and 2.1% at 120 min over baseline value in subjects consuming 150 ml of green tea, which was statistically not significant. However, total antioxidant capacity of plasma after consuming 300 ml of green tea showed a significant increase of 7.0% after 60 min and 6.2% after 120 min (P<0.0001), and after consuming 450 ml 12.0% after 60 min and 12.7% after 120 min over baseline value (P<0.0001).

CONCLUSIONS

Total antioxidant capacity of plasma was significantly increased after taking green tea in amounts of 300 and 450 ml. A positive increment according to green tea dosage was also observed.

SPONSORSHIP

This work was funded by the Pacific Corporation (Korea).

Cloning of a sesquiterpene cyclase and its functional expression by domain swapping strategy

Sesquiterpene cyclase, the first committed step enzyme from the general isoprenoid building block farnesyl pyrophosphate (FPP) for the synthesis of phytoalexin capsidiol, was isolated from the UV-C treated leaves of Capsicum annuum. This sesquiterpene cyclase, termed as CASC2 showing 77% amino acid identity with the previously cloned sesquiterpene cyclase CASC1, was composed of 560 amino acids with a calculated molecular mass of 64,907. The mRNA expression pattern of CASC2 was very similar to that of CASC1 during the time course of UV-C irradiated leaves of pepper on RNA blot analysis by using each specific probe. The heterologous expression in Escherichia coli using the CASC2 full length failed; however the chimeric construct of CASC2 in which the amino terminal 164 amino acid substituted by the equivalent portion of either CASC1 or tobacco sesquiterpene cyclase was capable of expressing the functional sesquiterpene cyclase activities. The radio-labeled enzymatic products catalyzed by the partially purified chimeric CASC2 were comigrated with authentic radio-labeled sesquiterpene on thin layer chromatography.

Distribution of haptoglobin phenotypes in a Korean population, using the semi-automated PhastSystem

We have established a new phenotyping method for haptoglobin, based on sodium dodecyl sulphate-polyacrylamide gel electrophoresis using the PhastSystem (Pharmacia Biotech, Uppsala, Sweden), followed by immunoblotting for detection. We measured haptoglobin concentrations and determined the haptoglobin phenotypes of 316 healthy Koreans using this method: 31 (9.8%) were of Hp 1-1 type, 140 (44.3%) of Hp 2-1 type and 145 (45.9%) of Hp 2-2 type. The haptoglobin allele frequencies were calculated to be 0.32 for Hp1 and 0.68 for Hp2. We were able to visualize up to 12 bands from the human Hp 2-2 polymeric series, with molecular weights in the range 171.9 x 10(3) to 802.2 x 10(3). The reference range of serum haptoglobin concentrations obtained by the IFCC (International Federation of Clinical Chemistry) standard method was 0.27-2.14 g/L. The serum haptoglobin concentration in Koreans was similar to that of Caucasians, but the Hp1 allele frequency was lower in Koreans. Our method could be used in clinical laboratories as a simple and practical method of haptoglobin phenotyping. In addition, the Hp 2-2 polymeric series could be used as high molecular weight standards.

Telomere length changes in patients undergoing hematopoietic stem cell transplantation

Telomere length indicates the replicative history of cells, serving as a molecular measure of the replicative potential remaining in cells. To investigate telomere length changes in hematopoietic stem cells, patients undergoing hematopoietic stem cell transplantation (HSCT) were evaluated. Fifteen patients after allogeneic bone marrow transplantation (allo-BMT group), seven patients after autologous peripheral blood stem cell transplantation (auto-PBSCT group), and 39 healthy controls were studied. Telomere length was measured in peripheral mononuclear cells by Southern blot hybridization. There was no significant difference between the allo-BMT and the auto-PBSCT groups. In the allo-BMT group, the mean telomere length of recipients was 2.01 kb shorter than that of their donors (P = 0. 008), and was 1.59 kb shorter than that of age-matched putative normal controls (P = 0.002). Telomere shortening in the allo-BMT group was equivalent to 41.4 years of aging in the donors, and to 52. 4 years of aging in the normal controls. The mean telomere length in the auto-PBSCT group was 2.36 kb shorter than that of the age-matched putative controls (P = 0.043), which was equivalent to 61.5 years of aging in normal controls. The extent of telomere shortening in the allo-BMT group showed a trend to negative correlation with the number of mononuclear cells infused. These findings suggest that hematopoietic stem cells after HSCT lose telomere length and these shortened telomeres may result in a higher incidence of clonal disorders later in life.