Aluminium reduces sugar uptake in tobacco cell cultures: a potential cause of inhibited elongation but not of toxicity

Aluminium is well known to inhibit plant elongation, but the role in this inhibition played by water relations remains unclear. To investigate this, tobacco (Nicotiana tabacum L.) suspension-cultured cells (line SL) was used, treating them with aluminium (50 μM) in a medium containing calcium, sucrose, and MES (pH 5.0). Over an 18 h treatment period, aluminium inhibited the increase in fresh weight almost completely and decreased cellular osmolality and internal soluble sugar content substantially; however, aluminium did not affect the concentrations of major inorganic ions. In aluminium-treated cultures, fresh weight, soluble sugar content, and osmolality decreased over the first 6 h and remained constant thereafter, contrasting with their continued increases in the untreated cultures. The rate of sucrose uptake, measured by radio-tracer, was reduced by approximately 60% within 3 h of treatment. Aluminium also inhibited glucose uptake. In an aluminium-tolerant cell line (ALT301) isogenic to SL, all of the above-mentioned changes in water relations occurred and tolerance emerged only after 6 h and appeared to involve the suppression of reactive oxygen species. Further separating the effects of aluminium on elongation and cell survival, sucrose starvation for 18 h inhibited elongation and caused similar changes in cellular osmolality but stimulated the production of neither reactive oxygen species nor callose and did not cause cell death. We propose that the inhibition of sucrose uptake is a mechanism whereby aluminium inhibits elongation, but does not account for the induction of cell death

Comparison of separation efficiency of benzene carboxylate derivatives for the determination of chloride, sulfate and nitrate ions in river water by indirect photometric ion chromatography

吸光光度検出器を用いたイオンクロマトグラフィーによる河川水中の塩化物イオン,硫酸イオン及び硝酸イオンの分析を目的とし本研究を行った.溶離イオンとして,2価,3価及び4価のベンゼンカルボン酸誘導体を比較した.河川水に含まれる程度の塩化物,硫酸,硝酸イオンの定量のためにはトリメリテートイオン(1,2,4-ベンゼントリカルボン酸イオン)が有用であることが分かった.陰イオン交換カラム(TSK gel IC-Anion-PW,4.6mmi.d×50mm)を用いることにより,塩化物,硫酸,硝酸イオンを約4分で分離定量できた.検量線は塩化物イオン(0.8~10)×10(-4)M,硫酸イオン(4.4~4)×10(-4)M,硝酸イオン(0.1~20)×10(-4)Mの範囲で良好な直線となった.普通河川水中に存在する程度のイオソは定量を妨害しない.再現性は各イオンとも相対標準偏差で1.5%以内であった.検出限界は塩化物イオン0.1ppm,硫酸イオソ0.2ppm,硝酸イオン0.1ppmであった.実際試料(河川水,水道水)に応用し,満足のいく結果を得た.Rapid and sensitive determination of chloride, sulfate and nitrate ions in river water was achieved by ion chromatography with UV photometric detector. Comparison of elution ability of eluent ions was made by using phthalate, hemimellitate, trimellitate, trimesate and pyromellitate ions at pH 7.5. Trimellitate solution (1,2,4-benzenetricarboxylate, 4×10(-4) M) is superior to other eluent ions because of its strong light-absorption at longer wavelength beyond 250 nm, suitable ability of elution for chloride, sulfate and nitrate ions, low price, high purity and easy availability. An anion exchange column (TSK gel IC-Anion-PW, 4.6 mm i.d.×50 mm) was used. Twenty microliters of sample solution was injected and decrease in absorbance of the trimellitate eluent at 250300 nm was detected. The calibration curves were linear in the range of (0.810)×10(-4) M for chloride, (0.44)×10(-4) M for sulfate and (0.120)×10(-4) M for nitrate. By the proposed method, chloride, sulfate and nitrate in river water were determined within four min. The relative standard deviations of ten measurements of tap water were 0.35% for chloride, 0.56% for sulfate and 1.3% for nitrate, respectively

YIPF5 mutations cause neonatal diabetes and microcephaly through endoplasmic reticulum stress

Neonatal diabetes is caused by single gene mutations reducing pancreatic pcell number or impairing beta cell function. Understanding the genetic basis of rare diabetes subtypes highlights fundamental biological processes in beta cells. We identified 6 patients from 5 families with homozygous mutations in the MPS gene, which is involved in trafficking between the endoplasmic reticulum (ER) and the Golgi. All patients had neonatal/early-onset diabetes, severe microcephaly, and epilepsy. YIPF5 is expressed during human brain development, in adult brain and pancreatic islets. We used 3 human beta cell models (YIPF5 silencing in EndoC-beta H1 cells, YIPF5 knockout and mutation knockin in embryonic stem cells, and patient-derived induced pluripotent stem cells) to investigate the mechanism through which YIPF5 loss of function affects beta cells. Loss of YIPF5 function in stem cell-derived islet cells resulted in proinsulin retention in the ER, marked ER stress, and beta cell failure. Partial YIPF5 silencing in EndoC-beta H1 cells and a patient mutation in stem cells increased the beta cell sensitivity to ER stress-induced apoptosis. We report recessive YIPF5 mutations as the genetic cause of a congenital syndrome of microcephaly, epilepsy, and neonatal/early-onset diabetes, highlighting a critical role of YIPF5 in beta cells and neurons. We believe this is the first report of mutations disrupting the ER-to-Golgi trafficking, resulting in diabetes.Peer reviewe