Journal articles: 'Isótopos de 13C e 15N'

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Ducatti, Carlos. "Aplicação dos isótopos estáveis em aqüicultura." Revista Brasileira de Zootecnia 36, suppl (July 2007): 1–10. http://dx.doi.org/10.1590/s1516-35982007001000001.

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O produto mais importante do conhecimento é a ignorância. A situação sugere a imagem de alguém que vive numa ilha de conhecimento cercado por um mar de ignorância. Quando a área dessa ilha aumenta pelo progresso da ciência, também aumenta o litoral, - a fronteira com o desconhecido. Esta expansão é o fruto mais valioso do conhecimento (David Gross, Nobel em Física, 2004). O uso dos isótopos estáveis dos bioelementos (CHON'S) presentes na Atmosfera, Hidrosfera, Litosfera e Biosfera enquadra-se neste contexto, surgindo como ferramenta de alto potencial em pesquisas nas diversas áreas das Ciências da Vida. Com organismos aquáticos, a aplicação dos isótopos estáveis do carbono (δ 13C) e do nitrogênio (δ 15N) tem ocorrido em diversas áreas. Em larvas de pacu Piaractus mesopotamicus, a técnica evidenciou a escolha voluntária entre organismos vivos e dieta seca pelos animais, desde as primeiras alimentações até o final da larvicultura. Na carcinicultura, o crescimento do Penaeus vannamei resultou do aproveitamento dos alimentos oferecidos e da produtividade primária do lago (biota). Por meio do balanço de massa e isotópico foi possível determinar a contribuição da biota, da ordem de 44 a 86% do carbono assimilado pelos animais durante o crescimento. Outro exemplo é com o caranguejo de mangue Sesarma rectum, em que sua preferência alimentar por Spartina alterniflora (C4) versus Rhizophora mangle (C3) ou Hibiscus tiliaceus (C3) foi evidenciada pelo modelo isotópico de duas fontes alimentares e os isótopos estáveis do carbono (δ13C). A técnica dos isótopos estáveis associada ao conhecimento dos conceitos básicos da variabilidade isotópica natural e ao uso criterioso das razões 13C/12C; ²H/¹H; 18O/16O; 15N/14N e 36S/34S revela-se como um avanço na fronteira dos conhecimentos, nas diversas reentrâncias do litoral da aqüicultura.

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Araujo, Priscila Cavalca de, José Roberto Sartori, Valquíria Cação da Cruz, Antonio Celso Pezzato, Carlos Ducatti, Ana Cristina Stradiotti, and Vanessa Cristina Pelícia. "Rastreabilidade de farinha de vísceras de aves por isótopos estáveis em penas de frangos de corte." Pesquisa Agropecuária Brasileira 46, no. 5 (May 2011): 537–44. http://dx.doi.org/10.1590/s0100-204x2011000500012.

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O objetivo deste trabalho foi detectar a presença de farinha de vísceras de aves (FV) na alimentação de frangos de corte, por meio da análise de penas por isótopos estáveis de carbono (13C/12C) e nitrogênio (15N/14N) e espectrofotometria de massas. Setecentos e vinte pintos machos Cobb foram submetidos aos seguintes tratamentos: ração vegetal (RV) à base de milho e farelo de soja, de 1 a 42 dias de idade; ração com 8% de farinha de vísceras de frango (FV), de 1 a 42 dias de idade; ração vegetal de 1 a 21 dias e ração com FV de 22 a 42 dias; ração vegetal de 1 a 35 dias e ração com FV de 36 a 42 dias; ração com FV de 1 a 21 dias, e ração vegetal de 22 a 42 dias; ração com FV de 1 a 35 dias, e ração vegetal de 36 a 42 dias. Foram colhidas amostras de penas de quatro aves por tratamento aos 7, 14, 21, 28, 35 e 42 dias de idade, que foram submetidas à análise isotópica de carbono (13C/12C) e nitrogênio (15N/14N) por espectrometria de massas. A aplicação da técnica dos isótopos estáveis de C e N a penas de frango de corte, após a utilização de farinha de vísceras na alimentação de frangos de corte, pelo período de até 21 dias, permite detectar a inclusão da FV na dieta.

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Silva, Alexandre Christofaro, Vinicius Evangelista Silva, Bárbara Pereira Christofaro Silva, Plínio Barbosa de Camargo, Rosana Cristina Pereira, Uidemar Morais Barral, Ana Maria Martins Botelho, and Pablo Vidal Torrado. "Composição lignocelulósica e isótopica da vegetação e da matéria orgânica do solo de uma turfeira tropical: II - substâncias húmicas e processos de humificação." Revista Brasileira de Ciência do Solo 37, no. 1 (February 2013): 134–44. http://dx.doi.org/10.1590/s0100-06832013000100014.

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Grande parte da matéria orgânica de Organossolos das turfeiras é composta por substâncias húmicas, formadas pela transformação de resíduos orgânicos pelos microrganismos do solo e pela polimerização dos compostos orgânicos em macromoléculas resistentes à degradação biológica. Os processos de humificação da matéria orgânica do solo (MOS) ainda são pouco compreendidos e o conhecimento sobre os precursores das substâncias húmicas é limitado, sendo apresentadas rotas diferentes para a formação dessas substâncias. Contudo, em todas as rotas, destaca-se a participação da lignina. Isótopos estáveis (13C, 15N) podem ser utilizados para rastrear processos de humificação da MOS, por meio da identificação de seus precursores. Este trabalho teve como objetivo avaliar comparativamente a composição isotópica da vegetação das fitofisionomias que colonizam uma turfeira tropical de altitude composta de Campo Limpo Úmido (CLU) e de Floresta Estacional Semidecidual (FES), em relação à composição isotópica das substâncias húmicas da MOS. A turfeira estudada ocupa 81,75 ha. Para as análises isotópicas e lignocelulósicas da vegetação, foram identificadas as espécies dominantes em cada fitofisionomia. Amostras de solo foram coletadas em três locais representativos sob cada fitofisionomia, a cada 5 cm de profundidade, até 50 cm. As substâncias húmicas dessas amostras foram fracionadas, assim como calculados os valores de δ13C e δ15N nas frações húmicas, respectivamente a partir da determinação dos isótopos estáveis 12C e 13C e 14N e 15N. Os teores de lignina e seus valores de δ13C são mais elevados na vegetação e MOS sob FES em relação à vegetação e MOS sob CLU. Os teores de humina são mais elevados entre as substâncias húmicas na MOS, sob as duas fitofisionomias; os de ácidos húmicos são mais elevados na MOS sob CLU, em relação à FES; e os de ácidos fúlvicos são mais elevados na MOS sob a FES, em relação ao CLU. O δ13C da lignina apresenta similaridade elevada em relação ao δ13C da humina, dos ácidos húmicos e dos ácidos fúlvicos. As variações na composição lignocelulósica das espécies que colonizam o CLU e a FES promovem diferenças nas taxas e nos produtos da humificação da MOS.

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Sepúlveda, Felipe, Patricio Gálvez, Blanca E. Molina-Burgos, and Sebastian A. Klarian. "Hábitos alimentarios del besugo Epigonus crassicaudus combinando contenido estomacal e isótopos estables." Revista de Biología Marina y Oceanografía 53 (August 1, 2018): 31. http://dx.doi.org/10.22370/rbmo.2018.53.0.1252.

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El besugo, Epigonus crassicaudus, es una especie de importancia económica para la actividad pesquera que opera en el centro-sur de Chile. A pesar de ello, poco es lo que se conoce respecto a su biología. En este sentido, este trabajo estudió los hábitos alimentarios combinando análisis estomacales y de estabilidad isotópica. Los resultados del análisis dan cuenta de la importancia de los peces mesopelágicos (Myctophidae, Stomiidae) en la dieta con un aporte del 80%, seguido por crustáceos (Sergestes arcticus) alcanzando un 10%. No se detectaron diferencias en la dieta en peces con distinto grado de madurez sexual. En tanto, los valores de los isótopos de nitrógeno y carbono mostraron valores de promedio de 17,12 ± 1,1 δ 15N y de -17,51 ± 0,7 δ 13C, respectivamente. La constitución de valores de δ 13C fue proporcional al tamaño corporal de los besugos: individuos de mayor tamaño habitan en ambientes más demersales que ejemplares de menor tamaño. De acuerdo a estos resultados, el besugo se sitúa como consumidor secundario.

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Grandal-d'Anglade, Aurora, Fernando Serrulla Rech, Víctor Tomás Botella, Marta Pérez Rama, María Gómez, and Emilio Ramil González. "Vida y muerte de dos mujeres de Brigantium (NW de Iberia) mediante isótopos estables y antropología forense." Cadernos do Laboratorio Xeolóxico de Laxe. Revista de Xeoloxía Galega e do Hercínico Peninsular 38 (October 28, 2015): 45–66. http://dx.doi.org/10.17979/cadlaxe.2015.38.0.3682.

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En este trabajo se obtienen datos antropológicos e isotópicos a partir de los restos óseos de dos individuos de edad tardorromana a efectos de reconstruir sus condiciones de vida y las causas de su muerte. Se trata de dos esqueletos femeninos conservados en el Museo Arqueolóxico de A Coruña datados entre los siglos III a VI dC. Se han aplicado técnicas de antropología forense para determinar patologías y lesiones que puedan haber afectado a los individuos estudiados. Para el estudio de paleodieta, se ha extraído colágeno óseo que se analiza mediante espectrometría de masas de relaciones isotópicas. Las relaciones isotópicas de 13C/12C y 15N/14N obtenidas se comparan con datos procedentes de otras poblaciones contemporáneas. Los perfiles antropológicos confirman que se trata de mujeres adultas jóvenes, de posible ancestralidad caucásica, con signos de hiponutrición e infección crónica y cuyas señales isotópicas del colágeno muestran una importante contribución de los moluscos en su dieta. Estos resultados concuerdan con los datos arqueológicos disponibles, reflejando el progresivo empobrecimiento de la ciudad durante la crisis del Bajo Imperio.

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López-van Oosterom, Maria Vanesa, Carolina Silvia Ocon, Ana Clara Ferreira, and Alberto Rodrigues-Capitulo. "Dieta de Pomacea canaliculata (Gastropoda: Ampullariidae) en su hábitat natural basada en análisis de contenidos digestivos e isótopos estables." Intropica 11 (December 21, 2016): 73. http://dx.doi.org/10.21676/23897864.1864.

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Pomacea canaliculata is native to Rio de la Plata basin, and it is invasive in most of South and Southeast Asia after accidental introduction during unsuccessful attempts to establish commercial aquaculture of this species, and being present, the number one pest of rice crops in the region. Investigations in its native habitat are still needed because fundamental issues of its trophic ecology remain unknown. The aim of this research was to study the diet of P. canaliculata in its natural habitat through gut content techniques and stable isotopes of 13C and 15N. Biological samples were taken from November 2009 to December 2010 in Carnaval stream, a characteristic Pampean stream. Samples for stable isotopes of 13C and 15N using of a mixing model were collected in November 2011. The trophic strategy diagram evinced a generalist diet with high consumption of detritus followed by the vascular plants and algae. The mixing model results indicated that the relative contribution to the diet was similar for all basal resources: fine and coarse particulate organic matter, epipelon and aquatic macrophytes (approximately 40 %). These results evidenced a strong dietary plasticity for the species.

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Barberena, Ramiro, Augusto Tessone, María Nella Quiroga, Florencia Gordón, Carina Llano, Alejandra Gasco, Jimena Paiva, and Andrew Ugan. "Guanacos y ecología isotópica en el norte del Neuquén: El registro de Cueva Huenul 1." Revista del Museo de Antropología 11, no. 1 (July 1, 2018): 7. http://dx.doi.org/10.31048/1852.4826.v11.n1.12005.

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En este trabajo se presentan los primeros resultados de ecología isotópica regional para el extremo norte de la provincia del Neuquén (Argentina). Esta información es clave para la reconstrucción de cambios ecológicos y paleodietas humanas a través del tiempo. Se exponen los resultados obtenidos a partir de la medición de isótopos estables de carbono (13C/12C) y nitrógeno (15N/14N) sobre el colágeno óseo de 39 muestras de fauna y una muestra humana procedentes de sitios arqueológicos de la localidad Barrancas-Buta Ranquil. Se presentan datos para cinco especies silvestres, aunque el foco del análisis se centra en guanaco (Lama guanicoe). La información es interpretada en el marco de los resultados obtenidos de muestreos de vegetación en la región, los cuales indican la distribución y abundancia de especies con las distintas vías fotosintéticas. Debido a su posición, adyacente al ecotono entre las comunidades fitogeográficas del Monte y la Patagonia, la región ofrece un contexto adecuado para el análisis de cambios ecológicos a través del tiempo. La totalidad de las especies vegetales relevadas en el muestreo sistemático siguen la vía fotosintética C3. En concordancia con esto, los valores de especies animales fueron relacionados a una cadena trófica C3. El entierro humano del sitio Buta Có Abajo registró valores que sugieren una dieta compuesta por guanacos y que además incluyó animales pequeños con valores más enriquecidos. En cuanto a los guanacos, se registraron diferencias isotópicas entre las muestras asignadas al Holoceno temprano y el tardío; estas últimas reflejan un mayor consumo de especies con vía fotosintética C3. Por último, en este conjunto de muestras, no se registró relación entre la altitud y los valores isotópicos de ?13C y ?15N, mientras que se observaría una tendencia latitudinal en la que los camélidos del centro sur de Mendoza presentan un mayor consumo de especies vegetales C4 que las procedentes del norte de Neuquén.

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Gil, Adolfo F., Lumila P. Menéndez, Juan P. Atencio, Eva A. Peralta, Gustavo A. Neme, and Andrew Ugan. "ESTRATEGIAS HUMANAS, ESTABILIDAD Y CAMBIO EN LA FRONTERA AGRÍCOLA SUR AMERICANA." Latin American Antiquity 29, no. 1 (December 19, 2017): 6–26. http://dx.doi.org/10.1017/laq.2017.59.

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El trabajo explora cuán estables fueron las estrategias humanas una vez que las poblaciones indígenas del centro-occidente argentino incorporaron cultígenos. Asimismo, evalúa si una vez incorporado el consumo de plantas domésticas, las estrategias fueron, o no, progresivamente apoyándose más sobre la producción y consumo de las mismas. El estudio compara tres sitios con restos humanos (Jaime Prats-1, Rincón del Atuel-1 y Cañada Seca-1) localizados entre sí a una distancia máxima de 40 km y en un valle considerado como el límite sur de la agricultura andina prehispánica. Estos sitios, que presentan una continuidad temporal, abarcan desde ca. 1900 (300 años posterior al registro inicial de las plantas domésticas en la región) a ca. 1400 años aP. Se comparan datos de isótopos estables (13C,15N,18O), morfometría craneal, mandibular y dental, junto a información contextual arqueológica. El sitio más antiguo, Jaime Prats-1, muestra semejanzas isotópicas y morfológicas con Cañada Seca-1, el más reciente, a pesar de no ser continuos en el tiempo. Ambos se diferencian de Rincón del Atuel-1, que temporalmente se intercala entre los dos. Los resultados señalan una mayor importancia del maíz en Rincón del Atuel-1, junto a una menor movilidad residencial, aunque en ninguno de los casos este recurso habría contribuido más del 30% a la dieta. Los sistemas humanos que ocuparon la frontera agrícola en estos primeros 500 años de uso de plantas domésticas muestran una alta variabilidad en su organización, sin cruzar umbrales que impidan retornar a sistemas de baja producción.

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Heikkinen, Harri A., Sofia M. Backlund, and Hideo Iwaï. "NMR Structure Determinations of Small Proteins Using only One Fractionally 20% 13C- and Uniformly 100% 15N-Labeled Sample." Molecules 26, no. 3 (February 1, 2021): 747. http://dx.doi.org/10.3390/molecules26030747.

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Uniformly 13C- and 15N-labeled samples ensure fast and reliable nuclear magnetic resonance (NMR) assignments of proteins and are commonly used for structure elucidation by NMR. However, the preparation of uniformly labeled samples is a labor-intensive and expensive step. Reducing the portion of 13C-labeled glucose by a factor of five using a fractional 20% 13C- and 100% 15N-labeling scheme could lower the total chemical costs, yet retaining sufficient structural information of uniformly [13C, 15N]-labeled sample as a result of the improved sensitivity of NMR instruments. Moreover, fractional 13C-labeling can facilitate reliable resonance assignments of sidechains because of the biosynthetic pathways of each amino-acid. Preparation of only one [20% 13C, 100% 15N]-labeled sample for small proteins (<15 kDa) could also eliminate redundant sample preparations of 100% 15N-labeled and uniformly 100% [13C, 15N]-labeled samples of proteins. We determined the NMR structures of a small alpha-helical protein, the C domain of IgG-binding protein A from Staphylococcus aureus (SpaC), and a small beta-sheet protein, CBM64 module using [20% 13C, 100% 15N]-labeled sample and compared with the crystal structures and the NMR structures derived from the 100% [13C, 15N]-labeled sample. Our results suggest that one [20% 13C, 100% 15N]-labeled sample of small proteins could be routinely used as an alternative to conventional 100% [13C, 15N]-labeling for backbone resonance assignments, NMR structure determination, 15N-relaxation analysis, and ligand–protein interaction.

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Martin, Gary E., Bruce D. Hilton, Patrick A. Irish, Kirill A. Blinov, and Antony J. Williams. "13C-15N Connectivity networksviaunsymmetrical indirect covariance processing of1H-13C HSQC and1H-15N IMPEACH spectra." Journal of Heterocyclic Chemistry 44, no. 5 (September 2007): 1219–22. http://dx.doi.org/10.1002/jhet.5570440541.

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Wrackmeyer, Bernd. "Vergleich der NMR-Parameter von Phosphaalkinen und Nitrilen / Comparison of NMR Parameters of Phosphaalkynes and Nitriles." Zeitschrift für Naturforschung B 43, no. 7 (July 1, 1988): 923–26. http://dx.doi.org/10.1515/znb-1988-0722.

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The values 1J(15N≡13C) from 15N satellites in the 13C NMR spectra for two nitriles [C6H5-C≡N, (CH3)2CH-C≡N] have been determined and δ(15N) for trimethylsilylcyanide has been con- firmed. This completed a set of NMR parameters in order to compare phosphaalkynes and nitriles. Linear relationships emerged for the following NMR parameters of phosphaalkynes and nitriles: δ(31Pp≡c)/δ(15NN≡C), δ(13CP≡C)/δ(13CN≡C) and 1J(31P=13C)/1J(15N≡13C). On the basis of the latter relationship a positive sign for 1J(31P≡13C) has been proposed. This is also corroborated by the sub- stituent-induced changes in the magnitude of 1J(13C≡13C) in corresponding alkynes.

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Hung, Ivan, Yuwei Ge, Xiaoli Liu, Mali Liu, Conggang Li, and Zhehong Gan. "Measuring 13C/15N chemical shift anisotropy in [13C,15N] uniformly enriched proteins using CSA amplification." Solid State Nuclear Magnetic Resonance 72 (November 2015): 96–103. http://dx.doi.org/10.1016/j.ssnmr.2015.09.002.

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Qu, Runlian, Lu Shan, Qun Sun, Yao Wei, Pengchi Deng, and Xiandeng Hou. "Quantification of 13C, 15N labelled compounds with 13C, 15N edited 1H Nuclear Magnetic Resonance spectroscopy." Talanta 224 (March 2021): 121839. http://dx.doi.org/10.1016/j.talanta.2020.121839.

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Wrackmeyer, Bernd, and Ēriks Kupče. "Some Applications of Ultrahigh Resolution 15N NMR Spectroscopy." Zeitschrift für Naturforschung B 53, no. 4 (April 1, 1998): 411–15. http://dx.doi.org/10.1515/znb-1998-0403.

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Abstract Ultrahigh resolution 15N NMR spectra were measured for two nitroalkanes (MeNO2 la, tBuNO2 1c), two isocyanates (tBuNCO 2c, Me3SiNCO 2d), four isothiocyanates (MeNCS 3a, EtNCS 3b, tBuNCS 3c, Me3SiNCS 3d), one carbodiimide (Me3SiNCNSiMe3 4d), one keteneimine [Me3SiNCC(SiMe3)2 5d], two sulphinyl imides (tBuNSO 6c, Me3SiNSO 6d), and N-tert-butyl-pyrrole 7c, in order to determine coupling constants J(15N ,I3C) and isotope induced chemical shifts 1∆12/13C (15N) at the natural abundance of the isotopes. The values 1∆12/13C (15N) can be separated into two groups, one dealing with NC single and another one with NC double bonds. In each group (with few exceptions), the values 1∆12/13C (15N) become more negative with a decrease in the absolute magnitude of l1J(l5N ,13C)l. The corresponding values 1∆14/15N (13C) show a sim ilar behaviour. However, N-substituted pyrroles appear to be exceptional in this respect.

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Hara, Takeshi, Yong Ji Xu, Hitomi Sasaki, Masaru Niitu, and Keijiro Samejima. "Syntheses of [13C,15N]-labeled polyamines." Journal of Labelled Compounds and Radiopharmaceuticals 43, no. 10 (2000): 1005–11. http://dx.doi.org/10.1002/1099-1344(200009)43:10<1005::aid-jlcr386>3.0.co;2-l.

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Wilmes, Rolf, and Manfred Winnewisser. "Preparation of 15N-13C-fulminic acid." Journal of Labelled Compounds and Radiopharmaceuticals 33, no. 2 (February 1993): 157–59. http://dx.doi.org/10.1002/jlcr.2580330211.

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White, Robert L., Kevin C. Smith, and Alphonse C. DeMarco. "Biosynthesis of 5-hydroxy-4-oxo-L-norvaline in Streptomyces akiyoshiensis." Canadian Journal of Chemistry 72, no. 7 (July 1, 1994): 1645–55. http://dx.doi.org/10.1139/v94-207.

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The biosynthesis of 5-hydroxy-4-oxo-L-norvaline (HON) in Streptomyces akiyoshiensis has been investigated using 13C-labelled substrates. Incorporations of 13C label from sodium [1-13C]-, [2-13C]-, and [1,2-13C2]acetate indicated that HON was formed from a four-carbon compound derived from the citric acid cycle and the methyl carbon of acetate. Feeding experiments using DL-[4-13C]- and DL-[2-13C,15N]aspartate demonstrated that aspartate served as the four-carbon precursor to HON. Both enantiomers of aspartate were metabolized by S. akiyoshiensis, but the D isomer was consumed at a slower rate. The distribution of 13C label in the intracellular L-glutamic acid isolated in these feeding experiments is consistent with the operation of the citric acid cycle in S. akiyoshiensis. A biosynthetic hypothesis that involves a condensation reaction between acetyl or malonyl CoA and the β-carboxyl group of aspartate, and subsequent oxidative decarboxylation, is proposed to account for the incorporation results. An analogous condensation step has been proposed for the biosynthesis of other natural products, including the carbapenem antibiotics. DL-[2-13C,15N]Aspartate was synthesized from [2-13C]diethylmalonate and potassium [15N]phthalimide via diethyl [2-13C,15N]phthalimidomalonate.

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Golebiewski, W. Marek, and Ian D. Spenser. "Biosynthesis of the lupine alkaloids. I. Lupinine." Canadian Journal of Chemistry 63, no. 10 (October 1, 1985): 2707–18. http://dx.doi.org/10.1139/v85-450.

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The mode of incorporation into lupinine of cadaverine, intramolecularly doubly labelled with,15N and with,13C at the C-atom adjacent to 15N, i.e., 13C, 15N-"bond-labelled", was determined by,13C nmr spectroscopy; lupinine is generated from two cadaverine-derived C5-units by a route which excludes a "dimeric" intermediate with C2v symmetry. The mode of incorporation of 2H from L-(2-2H)lysine, from (R)- and (S)-(1-2H)cadaverine, and from (2-2H)-Δ1-piperideine into lupinine was determined by 2H nmr spectroscopy. The results corroborate the conclusions from the 13C,15N experiment and they establish the stereochemistry of six of the steps in the biosynthetic conversion of L-lysine into lupinine.

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Carrijo, AS, AC Pezzato, and C. Ducatti. "Avaliação do Metabolismo Nutricional em Poedeiras pela Técnica dos Isótopos Estáveis do Ccarbono (13C/12C)." Revista Brasileira de Ciência Avícola 2, no. 3 (September 2000): 209–18. http://dx.doi.org/10.1590/s1516-635x2000000300003.

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Os isótopos estáveis do carbono que eram utilizados em estudos ecológicos e paleoecológicos apresentaram um incremento nos últimos trinta anos, na utilização em estudos dietéticos em animais. Entretanto, existem poucas informações sobre o padrão metabólico e sobre as taxas de turnover do 13C em aves. O presente experimento estabeleceu curvas de substituição e taxas de movimentação do 13C no ovo e no fígado de aves de postura adultas, pela substituição da ração comercial por dietas compostas de grãos dos ciclos fotossintéticos C3 e C4, durante 50 dias. A diferença no conteúdo isotópico do delta per mil do carbono-13 (delta‰ 13C) entre as duas dietas foi de 16,13‰. A taxa de substituição do 13C das dietas, nos tecidos, adequou-se num modelo exponencial, descrevendo o turnover do carbono nos tecidos analisados. As taxas de movimentação do 13C, nas aves alimentadas com dieta baseada em grãos C3, foi maior no fígado em relação ao ovo, com valores para a meia-vida de 2,9 e 3,7 dias, respectivamente. As aves que receberam ração com grãos C4 apresentaram uma taxa de turnover no ovo superior àquela obtida para o fígado, com meia-vida de 4,0 e 5,3 dias, respectivamente. Os valores do delta‰13C observados para ovo e fígado diferiram em aproximadamente 2‰ daqueles referentes às dietas.

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van der Wielen, Nikkie, Nadezda V. Khodorova, Walter J. J. Gerrits, Claire Gaudichon, Juliane Calvez, Daniel Tomé, and Marco Mensink. "Blood 15N:13C Enrichment Ratios Are Proportional to the Ingested Quantity of Protein with the Dual-Tracer Approach for Determining Amino Acid Bioavailability in Humans." Journal of Nutrition 150, no. 9 (July 25, 2020): 2346–52. http://dx.doi.org/10.1093/jn/nxaa205.

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ABSTRACT Background Assessment of amino acid bioavailability is of key importance for the evaluation of protein quality; however, measuring ileal digestibility of dietary proteins in humans is challenging. Therefore, a less-invasive dual stable isotope tracer approach was developed. Objective We aimed to test the assumption that the 15N:13C enrichment ratio in the blood increases proportionally to the quantity ingested by applying different quantities of 15N test protein. Methods In a crossover design, 10 healthy adults were given a semi-liquid mixed meal containing 25 g (low protein) or 50 g (high protein) of 15N-labeled milk protein concentrate simultaneous with 0.4 g of highly 13C–enriched spirulina. The meal was distributed over multiple small portions, frequently provided every 20 min during a period of 160 min. For several amino acids, the blood 15N- related to 13C-isotopic enrichment ratio was determined at t = 0, 30, 60, 90, 120, 180, 240, 300, and 360 min and differences between the 2 meals were compared using paired analyses. Results No differences in 13C AUC for each of the measured amino acids in serum was observed when ingesting a low- or high-protein meal, whereas 15N AUC of amino acids was ∼2 times larger on the high-protein meal (P < 0.001). Doubling the intake of 15N-labeled amino acids increased the 15N:13C ratio by a factor of 2.04 ± 0.445 for lysine and a factor between 1.8 and 2.2 for other analyzed amino acids, with only phenylalanine (2.26), methionine (2.48), and tryptophan (3.02) outside this range. Conclusions The amino acid 15N:13C enrichment ratio in the peripheral circulation increased proportionally to the quantity of 15N-labeled milk protein ingested, especially for lysine, in healthy adults. However, when using 15N-labeled protein, correction for, e.g., α-carbon 15N atom transamination is advised for determination of bioavailability of individual amino acids. This trial was registered at www.clinicaltrials.gov as NCT02966704.

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Sun, Zhaoan, Shuxia Wu, Biao Zhu, Yiwen Zhang, Roland Bol, Qing Chen, and Fanqiao Meng. "Variation of 13C and 15N enrichments in different plant components of labeled winter wheat (Triticum aestivum L.)." PeerJ 7 (October 2, 2019): e7738. http://dx.doi.org/10.7717/peerj.7738.

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Information on the homogeneity and distribution of 13carbon (13C) and nitrogen (15N) labeling in winter wheat (Triticum aestivum L.) is limited. We conducted a dual labeling experiment to evaluate the variability of 13C and 15N enrichment in aboveground parts of labeled winter wheat plants. Labeling with 13C and 15N was performed on non-nitrogen fertilized (−N) and nitrogen fertilized (+N, 250 kg N ha−1) plants at the elongation and grain filling stages. Aboveground parts of wheat were destructively sampled at 28 days after labeling. As winter wheat growth progressed, δ13C values of wheat ears increased significantly, whereas those of leaves and stems decreased significantly. At the elongation stage, N addition tended to reduce the aboveground δ13C values through dilution of C uptake. At the two stages, upper (newly developed) leaves were more highly enriched with 13C compared with that of lower (aged) leaves. Variability between individual wheat plants and among pots at the grain filling stage was smaller than that at the elongation stage, especially for the −N treatment. Compared with those of 13C labeling, differences in 15N excess between aboveground components (leaves and stems) under 15N labeling conditions were much smaller. We conclude that non-N fertilization and labeling at the grain filling stage may produce more uniformly 13C-labeled wheat materials, whereas the materials were more highly 13C-enriched at the elongation stage, although the δ13C values were more variable. The 15N-enriched straw tissues via urea fertilization were more uniformly labeled at the grain filling stage compared with that at the elongation stage.

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Tomlinson, Chris, Mahroukh Rafii, Ronald O. Ball, and Paul Pencharz. "Arginine synthesis from enteral glutamine in healthy adults in the fed state." American Journal of Physiology-Endocrinology and Metabolism 301, no. 2 (August 2011): E267—E273. http://dx.doi.org/10.1152/ajpendo.00006.2011.

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Recent studies have documented transfer of labeled nitrogen from [2-15N]glutamine to citrulline and arginine in fasting human adults. Conversely, in neonates and piglets we have shown no synthesis of arginine from [2-15N]glutamate, and others have shown in mice that glutamine is a nitrogen, but not a carbon donor, for arginine synthesis. Therefore, we performed a multitracer study to determine whether glutamine is a nitrogen and/or carbon donor for arginine in healthy adult men. Two glutamine tracers, 2-15N and 1-13C, were given enterally to five healthy men fed a standardized milkshake diet. There was no difference in plasma enrichments between the two glutamine tracers. 1-13C isotopomers of citrulline and arginine were synthesized from [1-13C]glutamine. Three isotopomers each of citrulline and arginine were synthesized from the [2-15N]glutamine tracer: 2-15N, 5-15N, and 2,5-15N2. Significantly greater enrichment was found of both [5-15N]arginine (0.75%) and citrulline (3.98%) compared with [2-15N]arginine (0.44%) and [2-15N]citrulline (2.62%), indicating the amino NH2 from glutamine is mostly transferred to arginine and citrulline by transamination. Similarly, the enrichment of the 1-13C isotopomers was significantly less than the 2-15N isotopomers, suggesting rapid formation of α-ketoglutarate and recycling of the nitrogen label. Our results show that the carbon for 50% of newly synthesized arginine comes from dietary glutamine but that glutamine acts primarily as a nitrogen donor for arginine synthesis. Hence, studies using [2-15N]glutamine will overestimate arginine synthesis rates.

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Lyčka, Antonín, Vladimír Macháček, and Josef Jirman. "15N, 13C, and 1H NMR spectra of 1-substituted-2,4,6-trinitrobenzenes." Collection of Czechoslovak Chemical Communications 52, no. 12 (1987): 2946–52. http://dx.doi.org/10.1135/cccc19872946.

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The 15N, 13C, and 1H NMR spectra of twenty 1-substituted-2,4,6-trinitrobenzenes have been measured in hexadeuteriodimethyl sulphoxide. The δ(15N) chemical shifts of 2-NO2 and 6-NO2 groups are different from those of 4-NO2 group. Except for 1-(4-subst. phenoxy)derivatives, the δ(15N-4) are shifted upfield as compared with δ(15N-2,6). The assignment of signals in the 15N NMR spectra was confirmed in three cases by measurements of selectively 15N-labelled compounds.

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De Masi, Marco Aurélio Nadal. "Aplicações de isótopos estáveis de O, C e N em estudos de sazonalidade, mobilidade e dieta de populações pré-históricas no sul do Brasil." Revista de Arqueologia 22, no. 2 (December 30, 2009): 55–76. http://dx.doi.org/10.24885/sab.v22i2.274.

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Análises de isótopos estáveis de 18/16O e 13/12C das águas e conchas de Anomalocardia brasiliana da Lagoa Conceição foram utilizadas no estudode sazonalidade das ocupações pré-históricas costeiras. A amostragem de dois anos (1996-1997 e 2002-2003) mostra que os valores de 18/ 16O e 13/12C são baixos quando temperatura e precipitação são elevadas no verão, onde predomina a cor cinza/opaca das conchas. No inverno predominam os valores altos de 18/16O e 13/12C, quando precipitação e temperatura são baixos e a cor branca/translúcida é predominante. Os resultados das análises demonstraram que as bases residenciais eram ocupadas durante o ano todo. Já com a análise dos isótopos estáveis de 13/12 C e 15/14N do colágeno de 82 esqueletos humanos provenientes de 15 sítios arqueológicos do litoral de Santa Catarina, foi possível fazer uma inferência indireta sobre a evolução da dieta destas populações. Os dados indicam uma adaptação costeira com uma dieta essencialmente marinha nos sítios mais antigos, havendo um aumento dos componentes terrestres na dieta com o passar do tempo, mas a mesma continua predominantemente marinha, mesmo após a aquisição da tecnologia cerâmica Jê. A presença de indivíduos de grupos caçadores coletores com uma dieta essencialmente terrestre é diagnosticada em alguns sítios com cerâmica Jê mais recentes. A mesma análise realizada em resíduos carbonizados de fundo de recipientes cerâmicos de uma estrutura subterrânea indica a utilização de plantas C4 (milho) e plantas C3 (legumes-feijão) por populações das Terras Altas do sul do Brasil ao redor de 320 a.C. Estes dados são confirmados quando comparados com os resultados das análises de isótopos de ä13C, ä15N de colágeno de indivíduos das Terras Altas os quais apresentam uso de plantas C4 em suas dietas ao redor de 700 a.C

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Olenginski, Lukasz T., and Theodore K. Dayie. "Quantifying the effects of long-range 13C-13C dipolar coupling on measured relaxation rates in RNA." Journal of Biomolecular NMR 75, no. 4-5 (April 29, 2021): 203–11. http://dx.doi.org/10.1007/s10858-021-00368-8.

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AbstractSelective stable isotope labeling has transformed structural and dynamics analysis of RNA by NMR spectroscopy. These methods can remove 13C-13C dipolar couplings that complicate 13C relaxation analyses. While these phenomena are well documented for sites with adjacent 13C nuclei (e.g. ribose C1′), less is known about so-called isolated sites (e.g. adenosine C2). To investigate and quantify the effects of long-range (> 2 Å) 13C-13C dipolar interactions on RNA dynamics, we simulated adenosine C2 relaxation rates in uniformly [U-13C/15N]-ATP or selectively [2-13C]-ATP labeled RNAs. Our simulations predict non-negligible 13C-13C dipolar contributions from adenosine C4, C5, and C6 to C2 longitudinal (R1) relaxation rates in [U-13C/15N]-ATP labeled RNAs. Moreover, these contributions increase at higher magnetic fields and molecular weights to introduce discrepancies that exceed 50%. This will become increasingly important at GHz fields. Experimental R1 measurements in the 61 nucleotide human hepatitis B virus encapsidation signal ε RNA labeled with [U-13C/15N]-ATP or [2-13C]-ATP corroborate these simulations. Thus, in the absence of selectively labeled samples, long-range 13C-13C dipolar contributions must be explicitly taken into account when interpreting adenosine C2 R1 rates in terms of motional models for large RNAs.

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Rudchik, A. T., A. A. Rudchik, O. E. Kutsyk, K. Rusek, K. W. Kemper, E. Piasecki, A. Stolarz, et al. "Elastic and inelastic scattering of 15N ions by 13C nuclei at energy 84 MeV." Nuclear Physics and Atomic Energy 22, no. 1 (March 25, 2021): 10–18. http://dx.doi.org/10.15407/jnpae2021.01.010.

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New experimental data of the 15N + 13C elastic and inelastic scattering were obtained at the energy Elab(15N) = 84 MeV. The data were analyzed within the coupled-reaction-channels method. The elastic and inelastic scattering of nuclei 15N + 13С as well as the more important nucleon and cluster transfer reactions were included in the channels-coupling scheme. The WS potential parameters for the 15N + 13С nuclei interactions in ground and excited states as well as deformation parameters of these nuclei were deduced. The contributions of one- and two-step transfers in the 15N + 13C elastic and inelastic scattering were estimated. The results of the 15N + 13С elastic scattering at the energy Elab(15N) = 84 MeV, obtained in this work, were compared with that of the 15N + 12С elastic scattering at the energy Elab(15N) = 81 MeV.

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Chiriac, Maria, Damian Axente, Nicolae Palibroda, and Constantin T. Craescu. "Synthesis of [1,3,6,7-15N, 8-13C] adenine." Journal of Labelled Compounds and Radiopharmaceuticals 42, no. 4 (April 1999): 377–85. http://dx.doi.org/10.1002/(sici)1099-1344(199904)42:4<377::aid-jlcr199>3.0.co;2-l.

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Chen, Qi-Feng, Yao-Nan Wang, Ling Wang, Xi-Xian Jian, Dong-Lin Chen, Ming Zhao, and Feng-Peng Wang. "Full Assignments of the 1H, 13C and 15N Magnetic Resonance Spectra of Two Porphyrin Compounds." Natural Product Communications 9, no. 4 (April 2014): 1934578X1400900. http://dx.doi.org/10.1177/1934578x1400900432.

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Two chlorin derivatives, rhodochlorin dimethyl ester (7) and chlorin-e6 trimethyl ester (8), were prepared from methyl pheophobide a (6) through base-degradation of the E ring and methylation of the carboxylic acids. Full assignments of the 1H, 13C and 15N magnetic resonance spectra of compounds 7 and 8 were made by 2D NMR techniques (1H-1H COSY, 1H-13C HMQC, 1H-13C HMBC, 1H-15N HMBC).

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JACKSON, A. A., R. BUNDY, A. HOUNSLOW, J. L. MURPHY, and S. A. WOOTTON. "Metabolism of lactose-[13C]ureide and lactose-[15N,15N]ureide in normal adults consuming a diet marginally adequate in protein." Clinical Science 97, no. 5 (September 28, 1999): 547–55. http://dx.doi.org/10.1042/cs0970547.

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Oral lactose-ureide is resistant to human digestive enzymes, but is fermented by the colonic microflora. Nine normal adults consuming a diet which provided 36 g of protein/day were given oral doses of lactose-[13C]ureide and lactose-[15N,15N]ureide. The appearance on breath of 13CO2 derived from lactose-[13C]ureide was followed for 48 h. The fate of 15N derived from lactose-[15N,15N]ureide was determined by measuring the recovery of 15N in stools and urine in various forms. About 80% of the label given as lactose-[13C]ureide was recovered on the breath, and about 80% of label given as lactose-[15N,15N]ureide was not recovered in stool, indicating that 80% of the dose was completely fermented. At least 5% of the labelled urea was absorbed and excreted as the intact molecule. Of the 15N derived from lactose-[15N,15N]ureide and available for further metabolic interaction, 67% was retained and 33% was excreted in urine. The time taken for [15N,15N]urea to appear in urine was similar for all subjects, but the appearance of either 13CO2 on the breath or [15N,14N]urea in urine varied. It is concluded that the hydrolysis of the sugar–urea bond may reflect oro–caecal transit time, but that other factors related to colonic bacterial metabolism determine the duration and extent of hydrolysis of urea by urease enzymes. Lactose-ureide can be used to probe the metabolic activity of the colonic microflora in normal individuals.

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Jirman, Josef, Antonín Lyčka, and Miroslav Ludwig. "13C and 15N NMR spectra of oximes prepared by nitrosation of activated methylene group." Collection of Czechoslovak Chemical Communications 55, no. 1 (1990): 136–46. http://dx.doi.org/10.1135/cccc19900136.

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15N and 13C NMR spectra have been measured of the compounds type XC(=NOH)Y, where X, Y = COCH3, CN, COOR, CONHR, and X +Y = C6H4(CO)2. The (E)-(Z) isomerism at the C=NOH bond has been studied by means of 15N labelling and stereospecific behaviour of the 2J(15N, 13C) coupling constants. The nitrosation of methyl cyanoacetate gives specifically the respective (E)-oxime, whereas that of acetoacetanilide gives the (Z)-isomer. The nitrosation of ethyl acetoacetate gives both (E)- and (Z)-oximes in a ratio of ca 1:10; the (E)-isomer is less stable and is transformed into the (Z)-isomer. The applicability of the 1J(13C, 13C) coupling constants and lanthanoid shift reagents to the study of (E)-(Z) isomerism of oximes with geminal carbonyl groups has also been verified. The 15N NMR chemical shifts of the oximes studied correlate with their respective pKa values measured in dimethyl sulfoxide according to the equation pKa = -0.11δ15N + 13.44.

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Wrackmeyer, Bernd. "Methylaminodiphenylborane — Application of 11B, 13C, 14N, 15N NMR." Zeitschrift für Naturforschung B 41, no. 1 (January 1, 1986): 59–62. http://dx.doi.org/10.1515/znb-1986-0112.

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11B, 13C, 14N, 15N NMR is used to study methylaminodiphenylborane (1). Compound 1 can be regarded as a model compound for studying BN(pp)π-. BC(pp)π interactions, for determining the barrier to rotation about the B-N bond and for the application of natural abundance 15N NMR to boron-nitrogen chemistry. The 13C NMR of 1 shows a large splitting of the 13C(para) resonances (in contrast to reports on similar compounds in the literature) as a consequence of hindered rotation about the BN bond. The difference in the 13C(para) nuclear shielding indicates different mesomeric interactions between the trigonal boron atom and the two phenyl groups.

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Brown, N. R., and C. E. Frazier. "Synthesis of labeled acrylamide andN-methylolacrylamide (NMA):15N-acrylamide,13C-NMA,15N-NMA, and13C,15N-NMA." Journal of Labelled Compounds and Radiopharmaceuticals 48, no. 14 (2005): 1031–39. http://dx.doi.org/10.1002/jlcr.1015.

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Farmer, Bennett T., and Luciano Mueller. "Simultaneous acquisition of [13C,15N]- and [15N,15N]-separated 4D gradient-enhanced NOESY spectra in proteins." Journal of Biomolecular NMR 4, no. 5 (September 1994): 673–87. http://dx.doi.org/10.1007/bf00404277.

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Fujiwara, Toshimichi, Kenji Sugase, Masatsune Kainosho, Akira Ono, Akira Ono, and Hideo Akutsu. "13C-13C and 13C-15N Dipolar Correlation NMR of Uniformly Labeled Organic Solids for the Complete Assignment of Their 13C and 15N Signals: An Application to Adenosine." Journal of the American Chemical Society 117, no. 45 (November 1995): 11351–52. http://dx.doi.org/10.1021/ja00150a038.

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Demirev, Plamen A., and Catherine Fenselau. "Determination of Isotope-Enrichment Ratios in Proteins by High-Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry." European Journal of Mass Spectrometry 8, no. 2 (April 2002): 163–67. http://dx.doi.org/10.1255/ejms.485.

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Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry has been applied for determining the 13C and 15N stable isotope content of a 10 kDa protein molecule. Purified samples of modified human ubiquitin, expressed in E. coli grown in a 13C and 13N isotope-enriched medium, are electrosprayed in a 4.7 T FT-ICR instrument. The intensity profiles of the isotopically-resolved envelope of the molecular ions in different charge states are averaged. The experimental data are then compared to theoretically-generated isotopic profiles for the same molecule at varying ratios of 12C: 13C and 14N: 15N isotope enrichment. The isotope-enrichment ratios giving the best overlap between simulated and experimental data correspond to estimates of incorporation from the 13C and 15N isotopes present in the microorganism growth medium.

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Rudchik, A. T., A. A. Rudchik, O. E. Kutsyk, K. Rusek, K. W. Kemper, E. Piasecki, A. Stolarz, et al. "12С(15N,14N)13C reaction mechanisms at energy 81 MeV." Nuclear Physics and Atomic Energy 21, no. 4 (December 25, 2020): 295–301. http://dx.doi.org/10.15407/jnpae2020.04.295.

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The new experimental data of the 12С(15N,14N)13С reaction cross-sections at the energy Еlab(15N) = 81 MeV were measured for the ground and excited states of 14N and 13C nuclei. The experimental data were analyzed within the coupled-reaction-channels method (CRC) using channels-coupling scheme with the 15N + 12С elastic scattering and one- as well as two-step transfers of nucleons and clusters performing CRC-calculations with the Woods - Saxon potentials (WS) for the entrance and exit reaction channels. The WS potential parameters for the 12С + 15N nuclear interaction were taken from the previously studied elastic and inelastic scattering of 15N ions by 12С nuclei at the energy 81 MeV, and the WS potential parameters for the 14N + 13С reaction exit channel were deduced from fitting of the 12С(15N,14N)13C reaction data. The spectroscopic factors (amplitudes) of transferred in the reaction nucleons and clusters, used in the CRC-calculations, were computed within translational invariant shell model of 1p-shell. It was found that transfers of neutrons (n) and deuterons (d) dominate in this reaction. Multi-step transfers of nucleons and clusters give small contributions to the reaction data.

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Maximo, Everaldo, José Albertino Bendassolli, Paulo César Ocheuze Trivelin, Alexssandra Luiza Rodrigues Molina Rossete, Claudinéia Raquel de Oliveira, and Clelber Vieira Prestes. "Produção de sulfato de amônio duplamente marcado com os isótopos estáveis 15N e 34S." Química Nova 28, no. 2 (March 2005): 211–16. http://dx.doi.org/10.1590/s0100-40422005000200008.

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Alexandre, A., J. Balesdent, P. Cazevieille, C. Chevassus-Rosset, P. Signoret, J. C. Mazur, A. Harutyunyan, et al. "Direct uptake of organic carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence." Biogeosciences Discussions 12, no. 23 (December 10, 2015): 19751–80. http://dx.doi.org/10.5194/bgd-12-19751-2015.

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Abstract. In the rhizosphere, the uptake of low molecular weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relatively to total uptake is important, organic C uptake is supposed to be low relatively to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and in which extent organic C absorbed by grass roots, under the form of either intact amino acids (AAs) or microbial metabolites, can feed the organic C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled AAs to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C-excess and 15N-excess) in the roots, stems and leaves, and phytoliths, as well as the 13C-excess in AAs extracted from roots and stems and leaves, were quantified relatively to a control experiment in which no labelled AAs were added. The net uptake of 13C derived from the labeled AAs supplied to the nutritive solution (AA-13C) by Festuca arundinacea represented 4.5 % of the total AA-13C supply. AA-13C fixed in the plant represented only 0.13 % of total C. However, the experimental conditions may have underestimated the extent of the process under natural and field conditions. Previous studies showed that 15N and 13C can be absorbed by the roots in several organic and inorganic forms. In the present experiment, the fact that phenylalanine and methionine, that were supplied in high amount to the nutritive solution, were more 13C-enriched than other AAs in the roots and stems and leaves strongly suggested that part of AA-13C was absorbed and translocated in its original AA form. The concentration of AA-13C represented only 0.15 % of the phytolith C (phytC) but was still 1.5 times higher in phytoliths than in leaves supporting that, ultimately, AA-13C was preferentially fixed in organic compounds subject to occlusion in phytoliths. Plausible forms of AA-13C and AA-15N absorbed and translocated, AA-13C fixation in phytoliths and implication of our finding for our understanding of the C cycle at the plant-soil interface are discussed.

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Tessier, Romain, Juliane Calvez, Nadezda Khodorova, Alain Quinsac, Romain Kapel, Olivier Galet, Daniel Tomé, Gheorghe Airinei, Robert Benamouzig, and Claire Gaudichon. "Confrontation of the “Dual Tracer” Indirect Method With Direct Ileal Sampling for Indispensable Amino Acid Digestibility of Sunflower Isolate in Humans." Current Developments in Nutrition 5, Supplement_2 (June 2021): 884. http://dx.doi.org/10.1093/cdn/nzab048_019.

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Abstract Objectives The direct assessment of ileal samples of amino acid (AA) digestibility is invasive in humans. A less invasive but indirect method, namely « dual tracer » was recently developed. It relies on the plasma isotopic enrichment ratio of two labeled protein, a reference protein or alternately AAs labeled with 13C and the test protein labeled with 15N. This recent method has not yet been challenged against direct measurement of ileal digestibility. Methods Seven healthy volunteers were intubated with naso-ileal tube. Every 30min for 4h, they ingested sunflower biscuits containing a total of 25g of 15N intrinsically labeled sunflower protein isolate. They also ingested 60g chocolate containing a total of 400mg of a mix of 13C algal individual AAs. Ileal contents were collected continuously for 8h following the first meal and plasma was sampled every 30min for 4h and hourly between 4 and 8h. 15N and 13C indispensable amino acid (IAA) ileal digestibility were determined by measuring 15N and 13C enrichment in AAs by GC-C-IRMS and AA content by UHPLC in ileal effluent. Plasma and meal 15N and 13C IAA enrichment were measured by GC-C-IRMS. Isotopic 15N/13C ratio were determined using area under the curve value for each isotope. Results Using direct ileal sampling, average IAA ileal digestibility was: (i) 88.5 ± 5.0% for sunflower isolate (15N) with values ranged from 85.8 ± 5.1% for threonine to 91.1 ± 5.8% for methionine, and (ii) 97.6 ± 1.7% for free AAs (13C) with values ranged from 95.9 ± 2.3% for lysine to 98.8 ± 0.8% for phenylalanine. With the “dual tracer” method, digestibility of isoleucine, leucine, threonine and valine was significantly lower than with ileal determination (from 7.9% for threonine to 24.3% for leucine), Methionine and phenylalanine values were aberrant (over 100%) For lysine, the difference between the two methods was not statistically different (4.7%, p = 0.49). Conclusions With our methodological conditions, the “dual tracer” method provides physiological values for most IAA except methionine and phenylalanine. However, values were low compared to ileal digestibility (about 10%) and interindividual variability was high. This less invasive method is promising but requires methodological improvements. Funding Sources French Research National Agency (ANR), financial support of SOFIPROTEOL under the FASO Project PRODIAL.

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Konuma, Tsuyoshi, Aritaka Nagadoi, Jun-ichi Kurita, and Takahisa Ikegami. "Analysis of Artifacts Caused by Pulse Imperfections in CPMG Pulse Trains in NMR Relaxation Dispersion Experiments." Magnetochemistry 4, no. 3 (July 30, 2018): 33. http://dx.doi.org/10.3390/magnetochemistry4030033.

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Nuclear magnetic resonance relaxation dispersion (rd) experiments provide kinetics and thermodynamics information of molecules undergoing conformational exchange. Rd experiments often use a Carr-Purcell-Meiboom-Gill (CPMG) pulse train equally separated by a spin-state selective inversion element (U-element). Even with measurement parameters carefully set, however, parts of 1H–15N correlations sometimes exhibit large artifacts that may hamper the subsequent analyses. We analyzed such artifacts with a combination of NMR measurements and simulation. We found that particularly the lowest CPMG frequency (νcpmg) can also introduce large artifacts into amide 1H–15N and aromatic 1H–13C correlations whose 15N/13C resonances are very close to the carrier frequencies. The simulation showed that the off-resonance effects and miscalibration of the CPMG π pulses generate artifact maxima at resonance offsets of even and odd multiples of νcpmg, respectively. We demonstrate that a method once introduced into the rd experiments for molecules having residual dipolar coupling significantly reduces artifacts. In the method the 15N/13C π pulse phase in the U-element is chosen between x and y. We show that the correctly adjusted sequence is tolerant to miscalibration of the CPMG π pulse power as large as ±10% for most amide 15N and aromatic 13C resonances of proteins.

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Brookes, ST, SJ Prosser, A. Linton, and T. Preston. "The application of automated 15N and 13C analysis to 13C breath tests." Clinical Nutrition 9, no. 1 (February 1990): I. http://dx.doi.org/10.1016/0261-5614(90)90089-b.

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Ramanathan, K. V., and S. J. Opella. "High-resolution solid-state 13C14N and 13C15N heteronuclear correlation spectroscopy." Journal of Magnetic Resonance (1969) 86, no. 2 (February 1990): 227–35. http://dx.doi.org/10.1016/0022-2364(90)90255-8.

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43

Knicker, Heike. "The feasibility of using DCPMAS 15N 13C NMR spectroscopy for a better characterization of immobilized 15N during incubation of 13C- and 15N-enriched plant material." Organic Geochemistry 33, no. 3 (March 2002): 237–46. http://dx.doi.org/10.1016/s0146-6380(01)00155-3.

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44

Webb, SC, RE Hedges, and SJ Simpson. "Diet quality influences the (&dgr ;)13C and (&dgr ;)15N of locusts and their biochemical components." Journal of Experimental Biology 201, no. 20 (October 15, 1998): 2903–11. http://dx.doi.org/10.1242/jeb.201.20.2903.

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To determine whether relative enrichments of 15N and 13C in locusts are influenced by diet, locust nymphs were raised from hatchlings to adults on either seedling wheat or maize. Maize provided less hexose sugars and protein per gram than did wheat. Maize also depends on the C4 form of photosynthesis, while wheat uses the C3 form; this difference in photosynthetic pathways produces two distinguishable ranges of 13C values.The lower-quality maize diet corresponded to a 5.1 increase in animal 15N, relative to diet, whereas the wheat diet corresponded to an increase of only 2.3 . The maize-fed animals were more 13C-depleted in lipid, trehalose and chitin than those fed wheat. The results for 15N and 13C suggest that substrate recycling occurred on the low-quality maize diet. Consequently, we examined the variations in the isotopic differences between locusts and their diet at the biochemical level.

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45

Wrackmeyer, Bernd, Klaus Schamei, and Max Herberhold. "13C- und 15N-NMR-spektroskopische Untersuchungen einiger Pentacarbonylchrom-Aminophosphan-Komplexe/13C and 15N NMR Spectroscopic Study of Some Pentacarbonylchromium-Aminophosphane Complexes." Zeitschrift für Naturforschung B 44, no. 1 (January 1, 1989): 55–62. http://dx.doi.org/10.1515/znb-1989-0114.

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13C and 15N NMR data are reported for the free aminophosphanes ʹBu3-nP(NH2)n (n = 1 (1), 2 (2)), for the corresponding pentacarbonylchromium complexes (OC)5Cr-P(ʹBu)3-n(NH2)n (n = 1 (3), n = 2 (4), n = 3 (5)), and for other (OC)5Cr-aminophosphane complexes such as (OC)5Cr-P(NMe2)3, (6 ) and a binuclear complex (7) in which the sulfurdiimide derivative ʹBu(NH2)P-NSN-P(NH2)ʹBu serves as the phosphane ligand. Various techniques (e.g. INEPT and reverse two-dimensional (2D) 1H {15N}-experiments) have been used for recarding the 15N NMR spectra at natural abundance. In contrast to suggestions in the literature, the relationship between the 13C NMR parameters for the axial and equatorial CO groups and the σ-donor/π-acceptor properties of the phosphane ligand is not straightforward. The 15N resonances of the (OC)5Cr complexes 3, 4, 6 are shifted to higher frequencies with respect to those of the free ligands, and there is a regular decrease in 15N nuclear shielding in the series of 3, 4, 5. The |1J(31P15N)| values vary between 17 and 65 Hz, the smaller values being observed for the (OC)5Cr complexes. The lack of a regular change in the magnitude of 1J(31P15N) in the series 3, 4, 5 indicates that this parameter is influenced by the nature of both the Cr-P and the P-N bonds as a function of the number of amino groups.

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46

Jirman, Josef, and Antonín Lyčka. "15N, 13C, and 1H NMR spectra of acylated ureas and thioureas." Collection of Czechoslovak Chemical Communications 52, no. 10 (1987): 2474–81. http://dx.doi.org/10.1135/cccc19872474.

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A series of 1-acylated and 1,3-diacylated (acyl = acetyl or benzoyl) ureas and thioureas have been prepared and their proton-coupled and proton-decoupled 15N, 13C, and 1H NMR spectra have been measured. All the signals have been assigned. The 15N NMR chemical shifts in 1-acylated ureas and thioureas are shifted downfield as compared with δ(15N) of urea and thiourea, resp. This shift is greater for N-1 than for N-3 nitrogen atoms in both the series. When comparing acylureas and acylthioureas it is obvious from the Δδ(15N) differences that the CS group is better than CO group in transferring the electron-acceptor effect of acyl group. The proton-coupled 15N NMR spectra of the acylureas dissolved in hexadeuteriodimethyl sulphoxide exhibit a doublet of NH group and a triplet of NH2 group at 25 °C. At the same conditions the acylthioureas exhibit a doublet of NH group, the NH2 group signal being split into a doublet of doublets with different coupling constants 1J(15N, H). The greater one of these coupling constants is due to the s-trans proton with respect to the sulfur atom of the thiourea.

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47

Růžička, Aleš, Vladimír Pejchal, Jaroslav Holeček, Antonín Lyčka, and Klaus Jacob. "119Sn, 15N, 13C, and 1H NMR Study of the Intramolecular Sn-N Donor-Acceptor Interaction in [2-(Dimethylaminomethyl)phenyl]stannanes." Collection of Czechoslovak Chemical Communications 63, no. 7 (1998): 977–89. http://dx.doi.org/10.1135/cccc19980977.

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119Sn, 15N, 13C, and 1H NMR spectra were studied for [2-(dimethylaminomethyl)phenyl]stannanes, R1R2R3R4Sn or R1R2R24Sn, where R1, R2, and R3 are 1-butyl, Cl or Br, the same or different, and R4 is 2-(dimethylaminomethyl)phenyl. The occurrence of intramolecular interaction between the nitrogen and tin atoms was demonstrated based on changes in the characteristic values of the NMR parameters of these nuclides (δ(15N), δ(119Sn), J(119Sn,15N), and their interrelations, as well as on the relatively high values of the coupling constants 3J(119Sn,13C(CH2)).

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48

Gallagher, Erin M., Lily Y. Young, Lora M. McGuinness, and Lee J. Kerkhof. "Detection of 2,4,6-Trinitrotoluene-Utilizing Anaerobic Bacteria by 15N and 13C Incorporation." Applied and Environmental Microbiology 76, no. 5 (January 15, 2010): 1695–98. http://dx.doi.org/10.1128/aem.02274-09.

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ABSTRACT 2,4,6-Trinitrotoluene (15N or 13C labeled) was added to Norfolk Harbor sediments to test whether anaerobic bacteria use TNT for growth. Stable-isotope probing (SIP)-terminal restriction fragment length polymorphism (TRFLP) detected peaks in the [15N]TNT cultures (60, 163, and 168 bp). The 60-bp peak was also present in the [13C]TNT cultures and was related to Lysobacter taiwanensis.

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49

Anderson-Altmann, Karen L., Cu G. Phung, Stylianos Mavromoustakos, Zhiwen Zheng, Julio C. Facelli, C. Dale Poulter, and David M. Grant. "15N Chemical Shift Tensors of Uracil Determined from 15N Powder Pattern and 15N-13C Dipolar NMR Spectroscopy." Journal of Physical Chemistry 99, no. 26 (June 1995): 10454–58. http://dx.doi.org/10.1021/j100026a006.

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50

Milićević, David, Roman Kimmel, Martin Gazvoda, Damijana Urankar, Stanislav Kafka, and Janez Košmrlj. "Synthesis of Bis(1,2,3-Triazole) Functionalized Quinoline-2,4-Diones." Molecules 23, no. 9 (September 10, 2018): 2310. http://dx.doi.org/10.3390/molecules23092310.

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Derivatives of 3-(1H-1,2,3-triazol-1-yl)quinoline-2,4(1H,3H)-dione unsubstituted on quinolone nitrogen atom, which are available by the previously described four step synthesis starting from aniline, were exploited as intermediates in obtaining the title compounds. The procedure involves the introduction of propargyl group onto the quinolone nitrogen atom of mentioned intermediates by the reaction of them with propargyl bromide in N,N-dimethylformamide (DMF) in presence of a potassium carbonate and the subsequent formation of a second triazole ring by copper catalyzed cyclisation reaction with azido compounds. The products were characterized by 1H, 13C and 15N NMR spectroscopy. The corresponding resonances were assigned on the basis of the standard 1D and gradient selected 2D NMR experiments (1H–1H gs-COSY, 1H–13C gs-HSQC, 1H–13C gs-HMBC) with 1H–15N gs-HMBC as a practical tool to determine 15N NMR chemical shifts at the natural abundance level of 15N isotope.

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Journal articles on the topic 'Isótopos de 13C e 15N'

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