Phosphorylation and dimerisation of transcription factor ATF-1

The CREB/ATF family of 'bZIP' transcription factors bind to promoter elements containing the sequence motif CGTCA and mediate a variety of transcriptional responses. One of the best characterised members is the cAMP-response-element-binding protein, CREB, which plays a critical role in cAMP-inducible transcription. In differentiated cells, PKA directly activates CREB by phosphorylation and CREB in turn can activate several functionally diverse downstream genes. Two other bZIP proteins, ATF-1 and CREM, are highly homologous to CREB, and can heterodimerise with CREB. The role of these CREB homologues, and in particular the role of ATF-1, is poorly understood. Undifferentiated F9 (UF9) cells are refractory to cAMP, but become cAMP-responsive following retinoic acid-induced differentiation. The UF9 cell phenotype is due in part to the presence of a titratable inhibitor of CREB which is lost or inactivated following differentiation. Interestingly, the level of ATF-1 protein (i.e. ATF-1 homodimer and CREB/ATF-1 heterodimer) is dramatically reduced following differentiation. Thus it is possible that ATF-1 may correspond to this inhibitor of CREB, and regulate the cAMP-response during differentiation of F9 cells. In addition, ATF-1 is of particular interest because its conformation is affected by phosphorylation in a cell type-specific manner. By mutational analysis, three serine residues have been identified which in cooperation with the NH2-terminal region are involved in ATF 1 phosphorylation. Interestingly, these serines map to a region that is homologous to a transcriptional activation domain in CREB, suggesting that phosphorylation of ATF-1 may regulate its transcriptional activity. Moreover it appears that ATF-1 phosphorylation is affected by dimerisation and by DNA-binding. This suggests that ATF-1 transcriptional activity may be regulated by phosphorylation in vivo in a highly complex manner

Deterioro de aceite de soja parcialmente hidrogenado empleado en la fritura de un alimento cárnico

Se estudió a escala de laboratorio, el deterioro de aceite de soja parcialmente hidrogenado, en la fritura en profundidad de un alimento cárnico milanesas, para evaluar su comportamiento en relación a las disposiciones del Código Alimentario Argentino (CAA). Se trabajó con dos partidas de aceite, en proceso discontinuo, con reposición de aceite fresco, calentándose a 180 ± 2o C., durante 42 y 56 h, respectivamente. El deterioro se siguió a través de la evolución de la acidez libre, compuestos polares, distribución de las especies de deterioro y composición en ácidos grasos. Primera partida, a las 42 h de calentamiento, los compuestos polares aumentaron desde 4,6 % a t’0 hasta 16 % (120 milanesas fritas). Segunda partida, 56 h de calentamiento, los compuestos polares aumentaron desde 2,5 hasta 27,6 % (160 milanesas fritas). Principal deterioro fue el térmico por la presencia de dímeros y polímeros de triglicéridos, seguido del hidrolítico. La acidez libre superó el límite del CAA de 1,25% en etapas muy tempranas del proceso. Se recomienda incluir en el CAA los compuestos polares como control del proceso de fritura industrial y revisar el valor de acidez libre que es extremadamente bajo.The deterioration of partially hydrogenated soybean oil used in deep fat frying of a meat food called milanesa for evaluating its behavior according to the Argentinian Food Codex (CAA) at laboratory scale was studied. Two different lots of the oil, in batch process, with fresh oil turnover were heated at 180o C ± 2o C for 42 and 56 h, respectively. Deterioration was followed through the evolution of free fatty acid percentage, polar compounds, distribution of these deterioration species and fatty acid composition. In the first lot, at 42 h of heating, polar compounds increased from 4.6% at t’ 0 to 16% (120 milanesas fried). In the second lot, at 56 h of heating, polar compounds increased from 2.5 to 27.6% (160 milanesas fried)The main deterioration was thermal, considering the presence of triglycerides polymers and dimers in polar compounds, followed by hydrolytic deterioration. The free fatty acid percentage was higher than the maximum level of 1.25% established in the CAA at an early stage of the frying process. According to the results of this study, it is recommended to include polar compound percentage as a measure of frying control processing and to check the free fatty acid value, which is considered too low.Fil: Juárez, María Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Masson, Lilia. Universidad de Chile; ChileFil: Samman, Norma Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

Deterioro de aceite de soja parcialmente hidrogenado empleado en la fritura de un alimento cárnico

The deterioration of partially hydrogenated soybean oil used in deep fat frying of a meat food called milanesa for evaluating its behavior according to the Argentinian Food Codex (CAA) at laboratory scale was studied. Two differebnt lots of the oil, in batch process, with fresh oil turnover were heated at 180ºC ± 2 ºC for 42 and 56 h, respectively. Deterioration was followed through the evolution of free fatty acid percentage, polar compounds, distribution of these deterioration species and fatty acid composition. In the first lot, at 42 h of heating, polar compounds increased from 4.6 % at t' 0 to 16 % (120 milanesas fried). In the second lot, at 56 h of heating, polar compounds increased from 2.5 to 27.6 % (160 milanesas fried). The main deterioration was thermal, considering the presence of triglycerides polymers and dimers in polar compounds, followed by hydrolytic deterioration. The free fatty acid percentage was higher than the maximum level of 1.25 % established in the CAA at an early stage of the frying process. According to the results of this study, it is recommended to include polar compound percentage as a measure of frying control processing and to check the free fatty acid value, which is considered too low.Se estudió a escala de laboratorio, el deterioro de aceite de soja parcialmente hidrogenado, en la fritura en profundidad de un alimento cárnico milanesas, para evaluar su comportamiento en relación a las disposiciones del Código Alimentario Argentino (CAA). Se trabajó con dos partidas de aceite, en proceso discontinuo, con reposición de aceite fresco, calentándose a 180 ± 2 ºC ., durante 42 y 56 h, respectivamente. El deterioro se siguió a través de la evolución de la acidez libre, compuestos polares, distribución de las especies de deterioro y composición en ácidos grasos. Primera partida, a las 42 h de calentamiento, los compuestos polares aumentaron desde 4.6 % a t'0 hasta 16 % (120 milanesas fritas). Segunda partida, 56 h de calentamiento, los compuestos polares aumentaron desde 2.5 hasta 27.6 % (160 milanesas fritas). Principal deterioro fue el térmico por la presencia de dímeros y polímeros de triglicéridos, seguido del hidrolítico. La acidez libre superó el límite del CAA de 1,25 % en etapas muy tempranas del proceso. Se recomienda incluir en el CAA los compuestos polares como control del proceso de fritura industrial y revisar el valor de acidez libre que es extremadamente bajo

A Roadmap for Using the UN Decade of Ocean Science for Sustainable Development in Support of Science, Policy, and Action

The health of the ocean, central to human well-being, has now reached a critical point. Most fish stocks are overexploited, climate change and increased dissolved carbon dioxide are changing ocean chemistry and disrupting species throughout food webs, and the fundamental capacity of the ocean to regulate the climate has been altered. However, key technical, organizational, and conceptual scientific barriers have prevented the identification of policy levers for sustainability and transformative action. Here, we recommend key strategies to address these challenges, including (1) stronger integration of sciences and (2) ocean-observing systems, (3) improved science-policy interfaces, (4) new partnerships supported by (5) a new ocean-climate finance system, and (6) improved ocean literacy and education to modify social norms and behaviors. Adopting these strategies could help establish ocean science as a key foundation of broader sustainability transformations

Identification of proteins that interact with CREB during differentiation of F9 embryonal carcinoma cells

The mammalian transcription factor CREB is thought to activate cAMP-inducible genes in a variety of differentiated cell types and is probably involved in other signalling pathways. Undifferentiated F9 embryonal carcinoma (UF9) cells are refractory to cAMP and become cAMP-responsive following differentiation to endoderm like cells. It has been proposed that UF9 cells contain a negative regulator(s) of the cAMP-response that might act through direct interaction with CREB. We have used a protein blotting assay and (32)P-labelled CREB to probe for CREB-binding proteins in nuclear extracts from F9 cells and to examine their abundance during differentiation. We find that ATF1 (a protein that is highly homologous to CREB) and a novel polypeptide(s) of ∼100 kDa (CBP100) are the major CREB-binding proteins in extracts from UF9 cells. As expected ATF1 is detected due to leucine zipper-dependent heterodimerisation with CREB. In contrast CBP100 interacts with CREB independently of the leucine zipper. The total amount of ATF1 and the amount of ATF1 that is complexed with CREB are substantially reduced following differentiation. In addition, ATF1 mRNA levels are lower in differentiated F9 cells indicating that a pretranslational mechanism contributes to the decreased ATF1 protein levels observed. CBP100 levels are also reduced or CBP100 is modified upon differentiation. We discuss the potential roles of ATF1 and CBP100 in regulating CREB activity during differentiation of F9 embryonal carcinoma cells

Optimal Activation of an Endogenous Gene by HOX11 Requires the NH(2)-Terminal 50 Amino Acids

The HOX11 homeobox gene was first identified through studies of the t(7;10) and t(10;14) chromosomal translocations of acute T-cell leukemia. In addition, analysis of Hox11(−/−) mice has demonstrated a critical role for this gene in murine spleen development. A possible mode of in vivo function for the HOX11 protein in these two situations is regulation of target genes following DNA binding via the homeodomain, but little is known about how HOX11 regulates transcription in vivo. By performing transcriptional studies in yeast and mammalian one-hybrid systems, a modular transcriptional transactivation region at the NH(2) terminus of HOX11 has been functionally dissected from other parts of the protein. This NH(2)-terminal region includes the previously identified short conserved Hep motif, which itself activates transcription in one-hybrid assays. The importance of the NH(2)-terminal region for the function of HOX11 in vivo was assayed by activating a HOX11-dependent gene in NIH 3T3 cells. Activation of this gene was found to be dependent upon an intact homeodomain in HOX11, but maximal activation was obtained only when the NH(2)-terminal 50 amino acids of HOX11 was present, showing that this region of HOX11 is important for in vivo transcriptional control of a chromosomal target gene

Two antioxidants are better than one.

New evidence suggests that the cellular oxygen-sensing hypoxia-inducible factor(HIF) pathway may be protected by a double buffer of cellular antioxidant defense. Key players in the oxygen-dependent regulation of this pathway are the prolyl hydroxylase domain-containing enzymes (PHDs) that catalyze the prolyl-4-hydroxylation of HIFα, dependent on the presence of oxygen, 2-oxoglutarate, and iron in the ferrous (Fe(2+)) form. Vitamin C is also required as a cofactor, possibly to maintain the catalytic iron center in its functional Fe(2+)) state, although both the mechanism and the in vivo requirement are not absolutely clear