Various radionuclides, including radioactive tellurium (Te), were released to the environment by the Fukushima nuclear power plant accident. The total amount of Te-127m released from the power plant was estimated to be 1.1 × 1015 Bq. The radioactive Te may have contributed to the internal radiation dose at the initial stage of the accident. However, data on the environmental behavior of radioactive Te are limited. In this study, therefore, the uptake of Te in plants was investigated. Radishes (Raphanus sativus var. sativus) were cultivated into a nutrient solution, grown for 20-30 days, and then their fine roots (taproots in the plant anatomy) and a part of fleshy roots (hypocotyls in the plant anatomy) were immersed for two hours into nutrient solutions with different Te and Cs concentrations. After soaking, plants were returned to the initial Te- and Cs-free nutrient solution for further maturation. ICP-MS measurements were made to assess concentrations of Te and Cs in the plants' leaves and fleshy roots (the fine roots were removed). Resulting differences among the individual plants were large. The leaf/fleshy root ratios of the concentration of Te and Cs were 0.09-1.14 and 1.59-5.00 on a fresh-matter basis, respectively. Both Te and Cs were absorbed by the radishes through the fine roots. There was a general tendency for Te to be retained in the fleshy roots, whereas Cs was mainly absorbed by the fine roots and then transferred to the leaves.
The metabolic pathway of Alzheimer's amyloid precursor protein (APP) involves restricted intracellular proteolysis by secretases, which leads to the secretion of the N‐terminal soluble APP (sAPP) and the generation of a cell‐associated C‐terminal fragment. The precise cellular sites at which these processes occur remain unknown. In this report, we describe the route of APP sorting and the processing site using novel systems with and without sorting signals on the APP molecule. One system involves the replacement of the C‐terminal ten amino acids of APP with Adenoviral E19 protein containing an endoplasmic reticulum (ER) retrieval signal (APPE19); the other involves deleting the last ten amino acids correponding to the replaced site (APPdeltaC10). APPE19 localized mainly within the cis/medial Golgi compartment and exclusively suppresses the secretion of APP. In contrast, deletion of the C‐terminal tail promotes sAPP secretion by a constitutive secretion pathway. Metabolic labeling followed by immunoprecipitation with anti‐APP antibody revealed that APPE19 is rapidly degraded within 30 min and that the subsequent intracellular turnover rate is decreased with 40 % of the protein retained within the cells even after a chase period a 3 h. In contrast, APPdeltaC10 is rapidly eliminated from the intracellular compartments and secreted into the culture medium. The surface internalization and recycling processes of this protein are relatively impaired compared with wild‐type APP. The ratios of the levels of production to secretion of sAPPα, the N‐terminal, soluble APP fragment released by α‐secretase, are proportional to the secretion efficiencies among APP species, suggesting the localization of α‐secretase within a compartment late in the constitutive secretion pathway. These secretion mutants which utilize ER targeting signals are useful tools for analyzing the location of secretases and the intracellular degradation system within a constitutive secretion pathway such as ER quality control.
Abstract Prior to the emergence of life, it is believed that only L ‐amino acids were selected for formation of proteins, and that D ‐amino acids were eliminated on the primitive Earth. Whilst homochirality is essential for life, recently the occurrence of proteins containing D ‐ β ‐aspartyl (Asp) residues from various tissues of elderly subjects has been reported. Here, we discuss the presence of D ‐ β ‐Asp‐containing proteins in the lens, ciliary body, drusen, and sclera of the eye, skin, cardiac muscle, blood vessels of the lung, chief cells of the stomach, longitudinal and circular muscles of the stomach, and small and large intestines. Since the D ‐ β ‐Asp residue occurs through a succinimide intermediate, this isomer may potentially be generated in proteins more easily than initially thought. UV Rays and oxidative stress can accelerate the formation of the D ‐ β ‐Asp residue in proteins.
Abstract Boron neutron capture therapy (BNCT) is a tumor -selective particle radiation therapy. In BNCT, p-boronophenyl alanine, which is actively taken up by tumor cells through LAT1 transporter, a member of the system L family of heterodimeric, sodium-independent, amino acid transporters, is administrated to patients, and thermal or epithermal neutron is irradiated to tumor tissue of the patients. Nuclear capture and fission reactions between boron-10 and thermal neutron occurred only in tumor cells produce high- linear energy transfer (LET) alpha particles and recoiling lithium-7 (7Li). These high LET particles have very short pathlength (5-9 μmeter), and kill boron-10 containing tumor cells sparing adjacent normal tissue cells. BNCT was applied to malignant glioma, the most devastating tumor and has prolonged the survival of malignant glioma patients. In this study, we comprehensively investigated the micro RNAs (miRNAs) in exosomes derived from BNCT-treated glioblastoma U87 MG cells using microarray. Comparing with non-treated cells, more than 300 up-regulated miRNAs or 100 down-regulated miRNAs were detected in BNCT-treated cells. From the results of the prediction analysis of the target genes which interact with the miRNAs, the pathway analysis was performed. We found significantly associated pathways, such as Focal adhesion-PI3K-Akt-mTOR, Ras, MAPK, etc. miRNAs in exosomes released from BNCT-treated glioblastoma cells may suppress such essential pathways for cell proliferation and survival.
Three different types of soil were collected at each of three locations: a persimmon orchard, an ume (Prunus mume, so to speak, ‘a Japanese apricot’) orchard, and a paddy field located 50-55 km northwest from Fukushima Daiichi Nuclear Power Plant. The goal was to investigate the involvement of microbes inhabiting these soils on the behavior of 137Cs. The soils were sterilized with gamma ray irradiation for 30 hours (absorbed dose of 60 kGy) or with high-pressure steam (autoclave sterilization) at 121°C for 20 minutes. A radish cultivar (Raphanus sativus var. sativus) was then cultivated in those soils for 45 days, and the harvested taproots and leaves were testing using a Ge semiconductor detector for concentration of 137Cs. The result showed that the concentration of 137Cs in radishes cultivated in the sterilized soils with autoclave sterilization or gamma ray irradiation were significantly higher than in those cultivated in the unsterilized soils. An increase in the plant available 137Cs could be caused by NH4+ arisen from the multiple effects of the structural change of the soil, decomposition of organic matter, and/or extinction of the microbes by sterilization.
