RESUMEN
Embedded ß-barrel proteins in the outer envelope membrane mediate most cellular trafficking between the cytoplasm and plastids. Although the TRANSLOCON AT THE OUTER ENVELOPE MEMBRANE OF CHLOROPLASTS 75-V (TOC75-V)/OUTER ENVELOPE PROTEIN OF 80 KDA (OEP80) complex has been implicated in the insertion and assembly of ß-barrel proteins in the outer envelope membrane of Arabidopsis (Arabidopsis thaliana) chloroplasts, relatively little is known about this process. CRUMPLED LEAF (CRL) encodes a chloroplast outer envelope membrane-localized protein, and its loss-of-function mutation results in pleiotropic defects, including altered plant morphogenesis, growth retardation, suppression of plastid division, and spontaneous light intensity-dependent localized cell death. A suppressor screen conducted on mutagenized crl mutants revealed that a missense mutation in OEP80 suppresses the pleiotropic defects of crl. Furthermore, we found that OEP80 complex formation is compromised in crl. Additionally, we demonstrated that CRL interacts with OEP80 in vivo and that a portion of CRL is present at the same molecular weight as the OEP80 complex. Our results suggest that CRL interacts with OEP80 to facilitate its complex formation. CRL is involved in plastid protein import; therefore, the pleiotropic defects in crl are likely due to the combined effects of decreased plastid protein import and altered membrane integration of ß-barrel proteins in the outer envelope membrane. This study sheds light on the mechanisms that allow ß-barrel protein integration into the plastid outer envelope membrane and the importance of this finding for plant cellular processes.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Cloroplastos/metabolismo , Cloroplastos/metabolismo , Proteínas de la Membrana/metabolismo , Plastidios/genética , Plastidios/metabolismo , Transporte de ProteínasRESUMEN
An analytical method for the determination of residues of 3 phenicol drugs (chloramphenicol, thiamphenicol and florfenicol) in Ayu (Plecoglossus altivelis) by LC-MS/MS was developed. We used the whole body of Ayu, including the bones and internal organs, in addition to muscle. Phenicols were extracted with 90% acetonitrile and an aliquot of the crude extract was cleaned up on a Florisil column (2 g), followed by defatting with n-hexane. The acetonitrile extract was evaporated and the solvent was replaced with phosphate buffer, then the extract was purified on a hydroxylated styrene-divinylbenzene copolymer column (200 mg). Finally, sample solution was passed through a deproteination cartridge filter with a lipid removal function. Chloramphenicol was quantitated by means of a calibration curve corrected with salogate standard (chloramphenicol-d5) and thiamphenicol and florfenicol were quantitated based on absolute calibration curves. This method was validated in accordance with the notification of the Ministry of Health, Labour and Welfare of Japan. As a result of the validation study, the trueness, repeatability and within-laboratory reproducibility were 85-103, 5-13 and 8-13%, respectively. This method is useful for inspecting residues of 3 phenicol drugs in whole body of Ayu efficiently. Moreover, when chloramphenicol and thiamphenicol are detected by this method, the quantitated value is applicable to decide the compliance of the sample with the specifications and standards of the Food Sanitation Law.
Asunto(s)
Antibacterianos/análisis , Antibacterianos/aislamiento & purificación , Cloranfenicol/análisis , Cloranfenicol/aislamiento & purificación , Cromatografía Liquida/métodos , Residuos de Medicamentos/análisis , Residuos de Medicamentos/aislamiento & purificación , Análisis de los Alimentos/métodos , Osmeriformes/metabolismo , Espectrometría de Masas en Tándem/métodos , Tianfenicol/análogos & derivados , Tianfenicol/análisis , Tianfenicol/aislamiento & purificación , Acetonitrilos , Animales , Legislación Alimentaria/normas , Extracción Líquido-Líquido/métodos , Reproducibilidad de los ResultadosRESUMEN
An analytical method for the determination of butroxydim in agricultural products by LC-MS was developed. Butroxydim was extracted with acetonitrile and an aliquot of the crude extract was cleaned up on an octadecyl silanized silica gel (C18) cartridge column (1,000 mg), followed by a salting-out step to remove water. Before purification on a silica gel (SI) cartridge column (690 mg), polar matrices were precipitated by adding ethyl acetate, n-hexane and anhydrous sodium sulfate successively. This process effectively removed caffeine and catechins and improved recovery when analyzing residual butroxydim in tea leaves. Recovery and repeatability were good; the relative standard deviations were less than 5% for all 12 tested agricultural products (brown rice, soybean, potato, spinach, cabbage, apple, orange, grapefruit, lemon, tomato, peas with pods, and tea). Average recoveries for 11 agricultural products, except for lemon, were 74-92%.
Asunto(s)
Butirofenonas/análisis , Cromatografía Liquida/métodos , Productos Agrícolas/química , Herbicidas/análisis , Herbicidas/aislamiento & purificación , Espectrometría de Masas/métodos , Oximas/análisisRESUMEN
An LC/MS/MS analysis method was developed for crustacean allergens, tropomyosin, and arginine kinase. A protein extract from shrimp was reduced, alkylated, and digested by trypsin. Peptide spectra were obtained using full scan analysis by LC/MS/MS, and we determined a sequence through a protein search. 22ADTLEQQNK30, 92IQLLEEDLER101, 113LAEASQAADESER125, 134SLSDEER140, 153FLAEEADR160, and 190IVELEEELR198 of tropomyosin and 152VSSTLSSLEGELK164 and 217TFLVWVNEEDHLR229 of arginine kinase were selected as the specific peptides, and optimal multiple-reaction monitoring conditions were used. The results obtained through the LC/MS/MS analysis correlated well with those using the ELISA method for various crustacean samples (r2>0.9). Moreover, unregulated species, such as krill or insects, which produce positive results in some crustacean ELISA assays, can be differentiated by LC/MS/MS. These findings suggest that LC/MS/MS analysis may be effective for crustacean food allergen analysis.
Asunto(s)
Alérgenos/análisis , Proteínas de Artrópodos/análisis , Cromatografía Liquida/métodos , Crustáceos/química , Análisis de los Alimentos/métodos , Mariscos/análisis , Espectrometría de Masas en Tándem/métodos , Secuencias de Aminoácidos , Animales , Arginina Quinasa/análisis , Ensayo de Inmunoadsorción Enzimática , Hipersensibilidad a los Alimentos/prevención & control , Humanos , Datos de Secuencia Molecular , Fragmentos de Péptidos/análisis , Mapeo Peptídico , Proteolisis , Alineación de Secuencia , Tropomiosina/análisisRESUMEN
To elucidate the role of the prefrontal cortex in cognitive control of reaching movements, by multichannel near-infrared spectroscopy we examine changes in oxygenated hemoglobin (oxy-Hb) as an indicator of changes in regional cerebral blood flow in the bilateral dorsolateral (DLPFC), ventrolateral prefrontal cortex (VLPFC), and frontopolar cortex (FPC) during a reaching task with normal visual feedback (a consistent task) and a reaching task with flipped horizontal visual feedback (an inconsistent task). Subjects first perform 12 trials of the consistent task, and then perform six blocks of the inconsistent task, each of which consists of six trials. During the consistent task, oxy-Hb is increased only in the right VLPFC. During the first block of the inconsistent task, increases in oxy-Hb are observed in the bilateral DLPFC and the right VLPFC, whereas the increased oxy-Hb was gradually reduced as the block proceeded, which was accompanied by an improvement in the task performance. Eventually, there were no differences in the degree of change in oxy-Hb between the consistent and inconsistent tasks in the DLPFC and VLPFC. These findings suggest that the DLPFC is engaged in higher order cognitive control, while the right VLPFC is engaged in both higher and lower order cognitive controls.