Sample records for DESAMINACION (deamination)
from WorldWideScience.org

Sample records 1 - 5 shown.



1

Óxido nítrico, mutagénesis y cáncer/ Nitric oxide, mutagenesis and cancer

Díaz Arce, Dariel
2004-09-01

Resumen en español Se realizó una revisión de los posibles mecanismos generadores de mutaciones, mediados por las especies reactivas derivadas del NO (RNOS), y su relación con la carcinogénesis. Las RNOS potencialmente pueden dañar el ADN de forma directa mediante procesos de oxidación, desaminación y metilación de bases; e indirecta inhibiendo la actividad de las enzimas reparadoras. La oxidación de bases conduce fundamentalmente a transversiones y la desaminación a transiciones. (mas) La especie reactiva N2O3 puede reaccionar con aminas biógenas generando N-nitrosaminas, reconocidos agentes alquilantes. La inhibición de las enzimas se manifiesta por la reacción de las RNOS con grupos nucleofílicos de aminoácidos críticos para la actividad enzimática. Todos estos mecanismos pudieran favorecer de una u otra forma a la ocurrencia de mutaciones en el ADN, implicadas en la activación de oncogenes o inhibición de genes supresores de tumores, o ambas, favoreciendo así el surgimiento y desarrollo tumoral Resumen en inglés A review was made on the possible mechanisms generating mutations mediated by the reactive species derived from NO (RNOS) and their connection with carcinogenesis.The RNOS may damage the DNA directly by processes of oxidation, deamination and methylation of bases, and indirectly by inhibiting the activity of the repairing enzimes. The oxidation of bases leads mainly to transversions, whereas deamination leads to transitions. The reactive species N2O3 may react with biogen (mas) amines generating N-nitrosamines, known as alkylating agent. The inhibition of the enzimes is manifested by the reaction of the RNOS with nucleophylic groups of critical aminoacids for the enzimatic activity. All these mechanisms may favor in one way or another the occurrence of mutations in the DNA involved in the activation of oncogens and/or inhibitons of tumor-suppressing genes, enabling this way the appearance and development of tumors

Scientific Electronic Library Online (Spanish)

2

Modelo de simulación para estimar el balance calórico de bovinos en pastoreo

Mendoza Martínez, Germán D; Pinos Rodríguez, Juan M; Ricalde Velasco, Raúl; Aranda Ibáñez, Emilio M; Rojo Rubio, Rolando
2003-04-01

Resumen en portugués Desenvolveu-se um modelo determinístico para estimar o intercambio calórico de bovinos no pastoreio em temperaturas maiores à mínima temperatura crítica. Os componentes do modelo incluíram calor metabólico (CM), evaporação (CE), convecção (CV), condução (CD) e radiação. O CM se estimou a partir do consumo de energia metabolizável, pela excreção de uréia e a desaminação da proteína não depositada. As perdas respiratórias foram calculadas com base na (mas) pressão de saturação do vapor do ar inspirado e expirado. O volume respiratório foi estimado com base na temperatura ambiental (TA) e umidade relativa (HR). Considerou-se que as perdas pela pele eram proporcionais às respiratórias em função da TA. As perdas por CV foram calculadas assumindo uma forma cilíndrica do animal, em função da TA e velocidade do vento. As perdas de calor por CD para o solo foram calculadas de acordo ao tempo de pastoreio e de descanso em função à TA e HR. A radiação foi estimada pelas horas luz com uma constante solar de 1200kcal/h/m2/animal/d A principal fonte de ganho de calor foi a radiação (60-70%) seguida pelo calor metabólico (29-39%) com um mínimo ganho por excreção de uréia e desaminação (1%). A principal forma para dissipar o calor foi a evaporação (60%). O calor re-irradiado representou uma dissipação de 30% enquanto que por CV se dissipou o 2%, e 5% por CD. O modelo permite predizer mudanças no intercambio calórico sob diversas condições ambientais. Resumen en español Se desarrolló un modelo determinístico para estimar el intercambio calórico de bovinos en pastoreo en temperaturas mayores a la mínima temperatura crítica. Los componentes del modelo incluyeron calor metabólico (CM), evaporación (CE), convección (CV), conducción (CD) y radiación. El CM se estimó a partir del consumo de energía metabolizable, por la excreción de urea y la desaminación de la proteína no depositada. Las pérdidas respiratorias fueron calculada (mas) s en base a la presión de saturación del vapor del aire inspirado y expirado. El volumen respiratorio fue estimado en base a la temperatura ambiental (TA) y humedad relativa (HR). Se consideró que las pérdidas por piel eran proporcionales a las respiratorias en función de la TA. Las pérdidas por CV fueron calculadas asumiendo una forma cilíndrica del animal, en función de la TA y velocidad del viento. Las pérdidas de calor por CD hacia el piso fueron calculadas de acuerdo al tiempo de pastoreo y de descanso en función a la TA y HR. La radiación fue estimada por las horas luz con una constante solar de 1200kcal/h/m2/animal/d La principal fuente de ganancia de calor fue la radiación (60-70%) seguida por el calor metabólico (29-39%) con una mínima ganancia por excreción de urea y desaminacion (1%). La principal forma para disipar el calor fue la evaporación (60%). El calor re-irradiado representó una disipación del 30% mientras que por CV se disipó el 2%, y 5% por CD. El modelo permite predecir cambios en el intercambio calórico bajo diversas condiciones ambientales. Resumen en inglés A deterministic simulation model was developed to estimate heat exchange in cattle grazing in climates with temperatures over the minimum critical temperature. The model included metabolic heat (MH), evaporation heat loss (EHL), convection (CV), conduction (CD) and radiation. The MH was estimated from metabolizable energy intake, urea excretion and protein deamination. Respiratory heat losses (RHL) were estimated from saturation vapor pressure at body temperature and from (mas) inspired and expired air. Respiratory volume was obtained from ambient temperature (AT) and relative humidity (RH). It was assumed that skin latent heat loss is proportional to with RHL depending on ambient temperature. CH loss were calculated assuming a cylindrical shape of the animal as a function of AT and air velocity. CD heat loss to the floor was estimated according to grazing and resting time depending on AT and RH. Thermal radiant exchange was estimated with the solar constant (1200kcal/h/m2/animal/d). The main heat gain was by radiation (60-70%) followed by MH (29-39%), being minimum the heat associated to nitrogen metabolism (1%). The main mechanism to dissipate heat was by evaporation (60%). Re-irradiated heat contributed with 30% dissipation, whereas CV contributed 2% and CD 5%. The heat balance model can predict heat exchange response under different environmental conditions.

Scientific Electronic Library Online (Spanish)

3

RNA editing in plant mitochondria, cytoplasmic male sterility and plant breeding.

Araya, Alexandre; Zabaleta, Eduardo; Blanc, Valérie; Bégu, Dominique; Hernould, Michel; Mouras, Armand; Litvak, Simon
1998-04-01

Resumen en inglés RNA editing in plant mitochondria is a post-transcriptional process involving the partial change of C residues into U. These C to U changes lead to the synthesis of proteins with an amino acid sequence different to that predicted from the gene. Proteins produced from edited mRNAs are more similar to those from organisms where this process is absent. This biochemical process involves cytidine deamination. The cytoplasmic male sterility (CMS) phenotype generated by the inco (mas) mpatibility between the nuclear and the mitochondrial genomes is an important agronomical trait which prevents inbreeding and favors hybrid production. The hypothesis that RNA editing leads to functional proteins has been proposed. This hypothesis was tested by constructing transgenic plants expressing a mitochondrial protein translated from unedited mRNA. The transgenic "unedited" protein was addressed to the mitochondria leading to the appearance of mitochondrial dysfunction and generating the male sterile phenotype in transgenic tobacco plants. Male sterile plants were also obtained by expressing specifically a bacterial ribonuclease in the anthers. The economical benefits of artificially engineered male-sterile plants or carrying the (native) spontaneous CMS phenotype, implies the restoration to obtain fertile hybrids that will be used in agriculture. Restoration to fertility of transgenic plants was obtained either by crossing male-sterile plants carrying the "unedited" mRNA with plants carrying the same RNA, but in the antisense orientation or, in the case of plants expresing the ribonuclease, by crossing male-sterile plants with plants expressing an inhibitor specific of this enzyme

Scientific Electronic Library Online (Spanish)

4

Low pH adaptation and the acid tolerance response of Bifidobacterium longum biotype longum

Sánchez García, Borja; Champomier-Vergès, Marie-Christine; Collado, María del Carmen; Anglade, Patricia; Baraige, Fabienne; Sanz, Yolanda; González de los Reyes-Gavilán, Clara; Margolles Barros, Abelardo; Zagorec, Monique
2007-08-24

Digital.CSIC (Spain)

5

Characteristics of Modified Leghemoglobins Isolated from Soybean (Glycine max Merr.) Root Nodules

Jun, H. K.; Sarath, G.; Morán, José F.; Becana Ausejo, Manuel; Klucas, R. V.; Wagner, F. W.
1994-04-01

Digital.CSIC (Spain)