SummaryThe interaction of heme oxygenase-1 (HO-1) and caveolin in the cultured mouse mesangial cells (MMC) was investigated. In normal MMCs, high levels of caveolin-2 and low level of caveolin-1 at mRNA and protein level were observed without any detectable expression of caveolin-3. Upon treating the MMCs either with cadmium (Cd) or spermine NONOate (SPER/NO), expression of HO-1 mRNA and protein was increased. Caveolae rich membranous fractions from the MMCs treated with Cd or SPER/NO contained both HO-1 and caveolin-1 or caveolin-2. The experiments of immuno-precipitation showed complex formation between the HO-1 and caveolin-1 or caveolin-2 in the Cd treated MMCs. Confocal microscopic results also support co-localization of HO-1 and caveolin-1 or caveolin-2 at the plasma membrane. Co-localization of caveolins with HO-1 in caveolae suggested that caveolin could also play an important role in regulating the function of HO-1. IUBMB Life, 55: 525-532, 2003

Stem/branch maintenance respiration for a stand of Japanese red pine (Pinus densiflora) during the dormant season was examined using an open flow system. The stem/branch respiration rates per unit of volume were closely related to the thickness of the stems and branches, e.g. it decreased with increasing diameter ( p < 0.0001). When the respiration rates on the various positions were regressed against the stem temperature of the specific position, Q 10 values decreased with increasing diameter. The variation of Q 10 ranged from 1.28 to 6.4. These Q 10 variations should have represented the variation of stem/branch temperature within the tree. The increase in time lag corresponded with an increase in diameter. We estimated the annual maintenance respiration for stem and branches at stand level based on the respiration rate-diameter relation, the Q 10 -diameter relation, and the pipe model theory. In the P. densiflora stand, total annual maintenance respiration was estimated to be 2.55 t C ha À1 year À1 (1.40 t C ha À1 year À1 for stems, and 1.15 t C ha À1 year À1 for branches). This suggests that branch respiration is an important component of total aboveground woody respiration at the stand-level (about 45%). Within the distribution of annual maintenance respiration rates for each D class, the stem and branch of 25-30 cm D class was the highest, and accounted for 33% and 31% of total stem and branch respiration rates, respectively. According to our results and those of previous studies, maintenance respiration correlated positively with annual mean temperature and LAI, and correlated negatively with stand age and latitude. #

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