A hydrophilic cation-binding protein, PCaP1, was found to be stably bound to the plasma membrane in Arabidopsis thaliana. PCaP1 was quantified to account for 0.03-0.08% of the crude membrane ...fractions from roots and shoots. Its homologous protein was detected in several plant species. We investigated the mechanism of membrane association of PCaP1 by transient expression of fusion protein with green fluorescent protein. The amino-terminal sequence of 27 residues of PCaP1 had a potential to localize the fusion protein with green fluorescent protein to the plasma membrane, and the substitution of Gly at position 2 with Ala resulted in the cytoplasmic localization of PCaP1. When PCaP1 was expressed in the in vitro transcription/translation system with ³Hmyristic acid, the label was incorporated into PCaP1, but not into a mutant PCaP1 with Gly2 replaced by Ala. These results indicate that PCaP1 tightly binds to the plasma membrane via N-myristoylation at Gly2. We examined the binding capacity with phosphatidylinositol phosphates (PtdInsPs), and found that PCaP1 selectively interacts with phosphatidylinositol 3,5-bisphosphate and phosphatidylinositol 3,4,5-triphosphate. Competition assay with the N-terminal peptide and mutational analysis revealed that PCaP1 interacts with these two PtdInsPs at the N-terminal part. Interaction of PCaP1 with the membrane and PtdInsPs was not altered in the presence of Ca²⁺ at physiological concentrations. Furthermore, calmodulin associated with PCaP1 in a Ca²⁺-dependent manner, and its association weakened the interaction of PCaP1 with PtdInsPs. These results indicate that the N-terminal part is essential for both N-myristoylation and interaction with PtdInsPs, and that PCaP1 may be involved in intracellular signalling through interaction with PtdInsPs and calmodulin.
To reveal the in planta behaviour of caesium (Cs), the stable isotope
Cs was administered into 3-year-old Cryptomeria japonica seedlings by the application of
CsCl aqueous solution to the bark ...surface. The administered
Cs was quantified by ICP-MS measurements, which showed transportation of
Cs in an ascending direction in the stem. Distribution of
Cs was visualized using freeze-fixed C. japonica woody stem samples and cryo-time-of-flight secondary ion mass spectrometry/scanning electron microscopy (cryo-TOF-SIMS/SEM) analysis. Cryo-TOF-SIMS/SEM visualization suggested that
Cs was rapidly transported radially by ray parenchyma cells followed by axial transportation by pith and axial parenchyma cells. Adsorption experiments using powdered C. japonica wood samples and X-ray absorption fine structure (XAFS) analysis suggested that
Cs was in the hydrated state following its deposition into tracheid cell walls.
Background : Merkel cell carcinoma (MCC) is considered to be a rare neuroendocrine tumor originating from the Merkel cell of the skin. It commonly arises in the head and neck region, especially in ...sun-exposed skin areas or subcutaneous tissue ; however, it can also be found as a metastatic tumor in the lymph nodes. We treated a patient with Merkel cell carcinoma of a lymph node in the parotid gland, who did not exhibit any skin lesions. Case : A 70-year-old woman presented to us with a history of noticing a swelling in her right neck 15 months earlier. Fine-needle aspiration cytology revealed scattered small atypical cells, in addition to cell clusters exhibiting epithelial adhesion. The atypical cells had fine granular to smudgy chromatin and inconspicuous cytoplasm, similar to the features of a malignant lymphoma. The tumor was finally diagnosed as a Merkel cell carcinoma on the basis of the histological and immunohistochemical findings. No skin lesions were apparent yet. Conclusion : The characteristic features of MCC, such as the structural pattern of the single cells or cell clusters and the fine granular to smudgy chromatin, are very important cytological features for the diagnosis of MCC in cases where no skin lesions are evident.
In this article, we discuss the effects of long-term (17 months) aluminum (Al) treatment on the growth, root respiration rate, nutrient uptake rate, and photosynthetic activity of two-year-old ...Quercus serrata Thunb. seedlings. The seedlings were cultivated by supplying a nutrient solution with or without Al twice a week for 17 months in siliceous sand. After 5- and 17-month treatments, growth, root respiration rate, photosynthetic activity, and the concentration of minerals in the roots and leaves were measured. Al treatment for 5 and 17 months markedly enhanced the growth and photosynthetic activity, and Al treatment for 17 months stimulated the root respiration rate. Although Al treatment for 17 months significantly decreased the Ca, Mg, and P concentrations in leaves, this decrease did not cause deficiency symptoms because of significant increases in shoot biomass and photosynthetic activity. The results of this study reveal that an increase in photosynthetic activity supports growth enhancement induced by Al treatment in Q. serrata seedlings, and suggest that Al may act as a trigger in activating some metabolic functions that can induce growth.
Molybdenum (Mo) is an essential trace element for almost all living organisms including animals. Mo is used as a catalytic center of molybdo-enzymes for oxidation/reduction reactions of carbon, ...nitrogen, and sulfur metabolism. Whilst living cells are known to import inorganic molybdate oxyanion from the surrounding environment, the in vivo dynamics of cytosolic molybdate remain poorly understood as no appropriate indicator is available for this trace anion. We here describe a genetically encoded Forester-resonance-energy-transfer (FRET)-based nanosensor composed of CFP, YFP and the bacterial molybdate-sensor protein ModE. The nanosensor MolyProbe containing an optimized peptide-linker responded to nanomolar-range molybdate selectively, and increased YFP:CFP fluorescence intensity ratio by up to 109%. By introduction of the nanosensor, we have been able to successfully demonstrate the real-time dynamics of molybdate in living animal cells. Furthermore, time course analyses of the dynamics suggest that novel oxalate-sensitive- and sulfate-resistant- transporter(s) uptake molybdate in a model culture cell.
We investigated the physiological effect of rhizospheric aluminum (Al) on the activities of nitrate reductase and photosynthesis in Quercus serrata seedlings. The seedlings were cultured ...hydroponically in nutrient solution with or without 1 mM AlCl(3) (pH 4.0) for 14 days. After Al treatment for 3 days, the number of primordia of tertiary lateral roots on secondary lateral roots appeared to increase. As a result, the biomass of the roots significantly increased (by 5%) after Al treatment for 14 days. The uptake of NO(3)(-) by the seedlings from the culture medium was stimulated to 125% by Al treatment for 3 days. Al treatments for 7 and 14 days increased the nitrate reductase activities in the roots to 300% and 170%, respectively. Al treatment had no effect on photosynthetic activity or shoot biomass even after 14 days, although the chlorophyll content was slightly increased by Al treatment. These results suggest that the stimulation of root growth by Al might be closely related to metabolic changes including the increase in nitrate reductase activity in the leaves and roots.
Aluminium has a strong effect on many plant species, and there are reports of differing responses to Al between coniferous and broadleaf trees. A study was conducted on the effect of various ...concentrations of Al in nutrient solutions on tree root systems, using Chamaecyparis obtusa Sieb. (hinoki) and Quercus serrata Thumb. (konara) seedlings. Konara showed a tendency to enhance its root growth with increasing Al concentration in nutrient solution. The ability to change the rhizosphere pH decreased for both hinoki and konara with increasing Al concentration, but konara showed a higher pH change ability. It is suggested that konara and hinoki have different strategies to adjust the pH of acid soil.
To clarify the mobility of radiocesium (^ Cs) deposited in tree bark, we investigated the absorption properties of the Cs in the bark as the first step, using stable isotope (cold) ^ Cs. We compared ...absorption/desorption properties of ^ Cs with alkali metals, sodium (Na), potassium (K), and rubidium (Rb), in the bark of sugi (Cryptomeria japonica) and konara (Quercus serrata), which distribute a lot in Fukushima. Each alkali metal ion was absorbed to grinded bark by shaking with the 1 mol m^<-3> chloride solution of each alkali metal. Then, each alkali metal absorbed on the grinded bark was continuously extracted using 1 mol m^<-3> acetic acid ammonium (CH_3COONH_4) and 1 mol m^<-3> nitric acid (HNO_3) solution. In both tree species, Na^+ and K^+ were extracted almost same as or slightly more than absorbed amount in the bark. On the other hand, ^ Cs^+ and Rb^+ were extracted 57.6% and 38.3% in bark of sugi and 20.6% and 30.2% in bark of konara, respectively, therefore, most of absorbed ^ Cs^+ and Rb^+ seemed to be strongly fixed/absorbed in the bark. ^ Cs was extracted from the konara bark which was collected at Fukushima prefecture using the same procedure as above. As the result, ^ Cs extractability in konara bark was very low with 0.1 to 0.4%, except the sample after extraction by CH_3COONH_4 in the bark collected in Iwaki city. In this study, it was clarified that Cs fixed/absorbed in the tree bark is not easily removed.
PDF
