Copper elicits an increase in cytosolic free calcium in cultured tobacco cells

At concentrations greater than 0.1 mM, CuSO(4) provoked a rapid and sustained increase in the cytosolic free Ca(2+) concentration ([Ca(2+)](cyt)), in tobacco suspension culture cells expressing apoaequorin, a Ca(2+)-sensitive photoprotein. The increase was suppressed by treatment with LaCl(3), indicating that the increase is due to an influx of Ca(2+) from the apoplast through plasma membrane Ca(2+) channels. Although stimulation of H(2)O(2) production upon the CuSO(4) treatment (0.1 mM) was observed, treatment with catalase did not inhibit the increase in [Ca(2+)](cyt), and treatment with H(2)O(2) dose-dependently suppressed or delayed the increase. These results suggested that active oxygen species generated through copper-mediated reactions, or copper-mediated oxidative damages to plasma membrane, are not responsible for the increase. Treatment with sulfhydryl reagents, which alkylate or oxidize thiol groups, or acidification of the culture medium suppressed the increase in [Ca(2+)](cyt). These results demonstrated that copper causes an influx of Ca(2+) through plasma membrane Ca(2+) channels, and that plasma membrane thiol groups play an important role in activating the Ca(2+) channels.     

Role of cardiac renin-angiotensin system in sarcoplasmic reticulum function and gene expression in the ischemic-reperfused heart

The aim of this study was to explore the possible participation of cardiac renin-angiotensin system (RAS) in the ischemia-reperfusion induced changes in heart function as well as Ca²⁺-handling activities and gene expression of cardiac sarcoplasmic reticulum (SR) proteins. The isolated rat hearts, treated for 10 min without and with 30 M captopril or 100 M losartan, were subjected to 30 min ischemia followed by reperfusion for 60 min and processed for the measurement of SR function and gene expression. Attenuated recovery of the left ventricular developed pressure (LVDP) upon reperfusion of the ischemic heart was accompanied by a marked reduction in SR Ca²⁺-pump ATPase, Ca²⁺-uptake and Ca²⁺-release activities. Northern blot analysis revealed that mRNA levels for SR Ca²⁺-handling proteins such as Ca²⁺-pump ATPase (SERCA2a), ryanodine receptor, calsequestrin and phospholamban were decreased in the ischemia-reperfused heart as compared with the non-ischemic control. Treatment with captopril improved the recovery of LVDP as well as SR Ca²⁺-pump ATPase and Ca²⁺-uptake activities in the postischemic hearts but had no effect on changes in Ca²⁺-release activity due to ischemic-reperfusion. Losartan neither affected the changes in contractile function nor modified alterations in SR Ca²⁺-handling activities. The ischemia-reperfusion induced decrease in mRNA levels for SR Ca²⁺-handling proteins were not affected by treatment with captopril or losartan. The results suggest that the improvement of cardiac function in the ischemic-reperfused heart by captopril is associated with the preservation of SR Ca²⁺-pump activities; however, it is unlikely that this action of captopril is mediated through the modification of cardiac RAS. Furthermore, cardiac RAS does not appear to contribute towards the ischemia-reperfusion induced changes in gene expression for SR Ca²⁺-handling proteins.     

X-ray snapshots of quinone cofactor biogenesis in bacterial copper amine oxidase

The quinone cofactor TPQ in copper amine oxidase is generated by posttranslational modification of an active site tyrosine residue. Using X-ray crystallography, we have probed the copper-dependent autooxidation process of TPQ in the enzyme from Arthrobacter globiformis. Apo enzyme crystals were anaerobically soaked with copper; the structure determined from this crystal provides a view of the initial state: the unmodified tyrosine coordinated to the bound copper. Exposure of the copper-bound crystals to oxygen led to the formation of freeze-trapped intermediates; structural analyses indicate that these intermediates contain dihydroxyphenylalanine quinone and trihydroxyphenylalanine. These are the first visualized intermediates during TPQ biogenesis in copper amine oxidase.     

Effects of temperature, salinity and irradiance on the growth of the red tide dinoflagellate Gyrodinium instriatum Freudenthal et Lee

The effects of temperature, salinity and irradiance on the growth of the red tide dinoflagellate Gyrodinium instriatum Freudenthal et Lee were examined in the laboratory. Exposed to 45 different combinations of temperature (10–30 °C) and salinity (0–40) under saturating irradiance, G. instriatum exhibited its maximum growth rate of 0.7 divisions/day at a combination of 25 °C and a salinity of 30. Optimum growth rates (>0.5 divisions/day) were observed at temperatures ranging from 20 to 30 °C and at salinities from 10 to 35. The organism could not grow at ≤10 °C. In addition, G. instriatum burst at a salinity of 0 at all temperatures, but grew at a salinity of 5 at temperatures between 20 and 25 °C. It is noteworthy that G. instriatum is a euryhaline organism that can live under extremely low salinity. Factorial analysis revealed that the contributions of temperature and salinity to its growth of the organism were almost equal. The irradiance at the light compensation point (I₀) was 10.6 μmol/(m² s) and the saturated irradiance for growth (I_s) was 70 μmol/(m² s), which was lower than I_s for several other harmful dinoflagellates (90–110 μmol/(m² s)).     

Chloroplast phylogeny indicates that bryophytes are monophyletic

Opinions on the basal relationship of land plants vary considerably and no phylogenetic tree with significant statistical support has been obtained. Here, we report phylogenetic analyses using 51 genes from the entire chloroplast genome sequences of 20 representative green plant species. The analyses, using translated amino acid sequences, indicated that extant bryophytes (mosses, liverworts, and hornworts) form a monophyletic group with high statistical confidence and that extant bryophytes are likely sisters to extant vascular plants, although the support for monophyletic vascular plants was not strong. Analyses at the nucleotide level could not resolve the basal relationship with statistical confidence. Bryophyte monophyly inferred using amino acid sequences has a good statistical foundation and is not rejected statistically by other data sets. We propose bryophyte monophyly as the currently best hypothesis.     

Structural analysis of human hair single fibres by scanning microbeam SAXS

The origin of the curliness of human hair was revealed by scanning microbeam small angle X-ray scattering (SAXS), based on the nanostructure of keratin fibre arrangement. Scanning microbeam SAXS patterns of single hair fibres have been measured across the fibres and the differences in the patterns between the inner and the outer sides of the curvature were successfully detected. The analysis of the equatorial and azimuthal scattering intensity profiles showed that the arrangement of the intermediate filaments was different between the inner and the outer sides of the curvature. From the analogy with Merino and Romny wool, it is suggested that different types of cortices exist in human hair. It is concluded that, regardless of the ethnic origins (African, Caucasian, and Asian), the macroscopic curl shape of the hair fibre originate from the inhomogeneity of the internal nanostructure, arising from inhomogeneous distribution of two types of cortices.     

Myeloperoxidase has Directly-opposed Effects on Nitration Reaction--Study on Myeloperoxidase-deficient Patient and Myeloperoxidase-knockout Mice

Myeloperoxidase (MPO) catalyzes a nitration reaction to form nitrotyrosine in the presence of high nitrite, the metabolite of NO. Human leukocyte was shown to cause phenolic nitration using released MPO as a catalyst in the presence of nitrite. It opposes our previous finding that inhibition of MPO was essential for phenol nitration in human leukocyte study. To clarify the role of MPO, we utilized MPO-deficient human leukocytes and MPO-knockout mice. Even in the absence of exogenously added nitrite, high nitration product was observed in MPO-deficient leukocytes. In liver subjected to ischemia/reperfusion injury, a significantly higher amount of nitrotyrosine was produced in MPO-knockout mice than in normal mice. These results clearly demonstrate that MPO inhibits the accumulation of nitration products in vivo . Further experiments showed that MPO could degrade nitrotyrosine in the presence of glutathione. Thus, MPO-induced degradation of nitration products may cause the underestimation of the nitration product generated in vivo . We conclude that MPO may act predominantly to scavenge nitrotyrosine under physiological nitrite condition, and protect against injurious effect of nitrotyrosine.