Preventive effects of a water-soluble derivative of chroman moiety of vitamin E on lipid hydroperoxide-induced cell injuries and DNA cleavages through repressions of oxidative stress in the cytoplasm of human keratinocytes

ChrCrx (6-hydroxy-2, 5, 7, 8-tetramethyl-chroman-2-carboxylic acid) is a water-soluble analog in which 4', 8', 12'-trimethyltridecyl chain is deleted from an alpha-tocopherol molecule known as a hydrophobic antioxidant. Cell viability of human skin epidermal keratinocytes HaCaT was lowered by treatment with tert-butylhydroperoxide (t-BuOOH) of 50 microM for 48 h, designated as a subacute cytotoxicity, which was prevented by previous administration with ChrCrx in a dose-dependent manner as estimated by mitochondrial function-based WST-1 assay and cell morphological microscopy. In contrast an acute cytotoxicity due to treatment with t-BuOOH as dense as 200 microM for a period as short as 2 h could be also prevented with ChrCrx that was administered before and after, but was eliminated during, treatment with t-BuOOH. In contrast alpha-tocopherol was not cytoprotective against t-BuOOH. DNA strand cleavages were induced with t-BuOOH in the keratinocytes, and could be prevented by ChrCrx more effectively than alpha-tocopherol as assayed by TUNEL stain. The intracellular reactive oxygen species (ROS) was accumulated in a manner dependent on periods of t-BuOOH treatment in the cytoplasm more abundantly rather than the nucleus of keratinocytes, and was markedly diminished by ChrCrx as shown by fluorography using the redox indicator dye. Thus t-BuOOH-induced cell injuries and DNA cleavages of the keratinocytes can be prevented at least in part through efficient diminishment of ROS generated in the cytoplasm, to which the preferred distribution of ChrCrx may be advantageous over to the nucleus or membrane owing to its molecular hydrophilicity relative to alpha-tocopherol.     

Identification, evolution, and regulation of expression of Guinea pig trappin with an unusually long transglutaminase substrate domain

Trappins are found in human, bovine, hippopotamus, and members of the pig family, but not in rat and mouse. To clarify the evolution of the trappin genes and the functional significance of their products, we isolated the trappin gene in guinea pig, a species belonging to a rodent family distinct from rat and mouse. Guinea pig trappin was confirmed to encode the same domain structure as trappin, consisting of a signal sequence, an extra large transglutaminase substrate domain, and a whey acidic protein motif. Northern blot analysis and in situ hybridization histochemistry as well as immunohistochemistry demonstrated that guinea pig trappin is expressed solely in the secretory epithelium of the seminal vesicle and that its expression is androgen-dependent. We confirmed that guinea pig trappin is cross-linked by prostate transglutaminase and that the whey acidic protein motif derived from guinea pig trappin has an inhibitory activity against leukocyte elastase. Genome sequence analysis showed that guinea pig trappin belongs to the family of REST (rapidly evolving seminal vesicle transcribed) genes.     

Interaction of a small heat shock protein of the fission yeast, Schizosaccharomyces pombe, with a denatured protein at elevated temperature

We have expressed, purified, and characterized one small heat shock protein of the fission yeast Schizosaccharomyces pombe, SpHsp16.0. SpHsp16.0 was able to protect citrate synthase from thermal aggregation at 45 degrees C with high efficiency. It existed as a hexadecameric globular oligomer near the physiological growth temperature. At elevated temperatures, the oligomer dissociated into small species, probably dimers. The dissociation was completely reversible, and the original oligomer reformed immediately after the temperature dropped. Large complexes of SpHsp16.0 and denatured citrate synthase were observed by size exclusion chromatography and electron microscopy following incubation at 45 degrees C and then cooling. However, such large complexes did not elute from the size exclusion column incubated at 45 degrees C. The denatured citrate synthase protected from aggregation was trapped by a GroEL trap mutant at 45 degrees C. These results suggest that the complex of SpHsp16.0 and denatured citrate synthase at elevated temperatures is in the transient state and has a hydrophobic nature. Analyses of the interaction between SpHsp16.0 and denatured citrate synthase by fluorescence cross-correlation spectrometry have also shown that the characteristics of SpHsp16.0-denatured citrate synthase complex at the elevated temperature are different from those of the large complex obtained after the shift to lowered temperatures.     

Expression patterns of genes encoding carbohydrate-metabolizing enzymes and their relationship to grain filling in rice (Oryza sativa L.): comparison of caryopses located at different positions in a panicle

In rice, caryopses located at the base of the panicle have a lower growth rate than those at the tip of the panicle. The former and latter types of caryopses are called inferior and superior caryopses, respectively. Taking the different growth rate into consideration, sugar status and the expression of genes encoding carbohydrate-metabolizing enzymes in inferior caryopses were compared with those in superior caryopses. During the first 5 d after flowering, superior caryopses elongated rapidly, but inferior caryopses did not. At this phase, inferior caryopses had a low ratio of hexose to sucrose, high activity of acid invertase and the absence of the expression of the genes encoding the above enzymes except for two isoforms of cell wall invertase, OsCIN4 and INV1, in comparison with superior caryopses. At the start of caryopsis elongation in both superior and inferior caryopses, the hexose/sucrose ratio increased accompanied by gene expression of vacuolar invertase (INV3), sucrose synthase (RSus1) and ADP-glucose pyrophosphorylase (AGP-L2: D50317). Furthermore, the genes related to endospermal starch accumulation were expressed highly with the decrease in the hexose/sucrose ratio after its peak. Based on the comparison of superior and inferior caryopses, the possible mechanism of grain filling in rice is discussed.     

Structure and function of plant canopies

This section comprises a set of papers taken from those presented at a symposium held to commemorate the 50th anniversary of the Monsi-Saeki theory (1953), together with invited papers. The papers describe recent advances in the study of structure and function of plant canopies and are written by former students (and their collaborators) of Professors Monsi and Saeki. The topics cover construction and maintenance of efficient photosynthetic systems at leaf, individual plant and stand level. Canopy structure and function are analysed with respect to optimization and an evolutionarily stable strategy. A new translation of the original paper by Monsi and Saeki (1953) into English has been commissioned and is included in this section.     

Biomass allocation and leaf chemical defence in defoliated seedlings of Quercus serrata with respect to carbon-nitrogen balance

BACKGROUND AND AIMS: Both nutrient availability and defoliation affect the carbon-nutrient balance in plants, which in turn influences biomass allocation (e.g. shoot-to-root ratio) and leaf chemical composition (concentration of nitrogen and secondary compounds). In this study it is questioned whether defoliation alters biomass allocation and chemical defence in a similar fashion to the response to nutrient deficiency. METHODS: Current-year seedlings of Quercus serrata were grown with or without removal of all leaves at three levels of nutrient availability. KEY RESULTS: Plant nitrogen concentration (PNC), a measure of the carbon-nutrient balance in the plant, significantly decreased immediately after defoliation because leaves had higher nitrogen concentrations than stems and roots. However, PNC recovered to levels similar to or higher than that of control plants in 3 or 6 weeks after the defoliation. Nitrogen concentration of leaves produced after defoliation was significantly higher than leaf nitrogen concentration of control leaves. Leaf mass per plant mass (leaf mass ratio, LMR) was positively correlated with PNC but the relationship was significantly different between defoliated and control plants. When compared at the same PNC, defoliated plants had a lower LMR. However, the ratio of the leaf to root tissues that were newly produced after defoliation as a function of PNC did not differ between defoliated and control plants. Defoliated plants had a significantly lower concentration of total phenolics and condensed tannins. Across defoliated and control plants, the leaf tannin concentration was negatively correlated with the leaf nitrogen concentration, suggesting that the amount of carbon-based defensive compounds was controlled by the carbon-nutrient balance at the leaf level. CONCLUSIONS: Defoliation alters biomass allocation and chemical defence through the carbon-nutrient balance at the plant and at the leaf level, respectively.     

Respiration and reproductive effort in Xanthium canadense

* BACKGROUND AND AIMS: The proportion of resources devoted to reproduction in the plant is called the reproductive effort (RE), which is most commonly expressed as the proportion of reproductive biomass to total plant biomass production (RE(W)). Reproductive yield is the outcome of photosynthates allocated to reproductive structures minus subsequent respiratory consumption for construction and maintenance of reproductive structures. Thus, RE(W) can differ from RE in terms of photosynthates allocated to reproductive structures (RE(P)). * METHODS: Dry mass growth and respiration of vegetative and reproductive organs were measured in Xanthium canadense and the amount of photosynthates and its partitioning to dry mass growth and respiratory consumption were determined. Differences between RE(W) and RE(P) were analysed in terms of growth and maintenance respiration. * KEY RESULTS: The fraction of allocated photosynthates that was consumed by respiration was smaller in the reproductive organ than in the vegetative organs. Consequently, RE(P) was smaller than RE(W). The smaller respiratory consumption in the reproductive organ resulted from its shorter period of existence and a seasonal decline in temperature, as well as a slower rate of maintenance respiration, although the fraction of photosynthates consumed by growth respiration was larger than in the vegetative organs. * CONCLUSIONS: Reproductive effort in terms of photosynthates (RE(P)) was smaller than that in terms of biomass (RE(W)). This difference resulted from respiratory consumption for maintenance, which was far smaller in the reproductive organ than in vegetative organs.     

Overexpression of alpha enolase in hepatitis C virus-related hepatocellular carcinoma: association with tumor progression as determined by proteomic analysis

To identify proteins that could be molecular targets for diagnosis and treatment of hepatitis C virus-related hepatocellular carcinoma (HCV-related HCC), we used a proteomic approach to analyze protein expression in samples of human liver. Twenty-six pairs of tumorous and corresponding nontumorous liver samples from patients with HCV-related HCC and six normal liver samples were analyzed by two-dimensional gel electrophoresis and liquid chromatography-tandem mass spectrometry. One of the numerous spots that showed stronger intensity in tumorous than in nontumorous samples was identified as alpha enolase, a key enzyme in the glycolytic pathway. Expression of this protein increased with tumor dedifferentiation and was significantly higher in poorly differentiated HCC than in well-differentiated HCC. This pattern was reproduced by immunoblot analysis and immunohistochemistry. Expression of alpha enolase also correlated positively with tumor size and venous invasion. These results suggest that alpha enolase is one of the candidates for biomarkers for tumor progression that deserves further investigation in HCV-related HCC.