Disposition of a Glucose Load into Hepatic Glycogen by Direct and Indirect Pathways in Juvenile Seabass and Seabream

In carnivorous fish, conversion of a glucose load to hepatic glycogen is widely used to assess their metabolic flexibility towards carbohydrate utilization, but the activities of direct and indirect pathways in this setting are unclear. We assessed the conversion of an intraperitoneal glucose load (2 g.kg−1) enriched with [U-13C6]glucose to hepatic glycogen in juvenile seabass and seabream. 13C-NMR analysis of glycogen was used to determine the contribution of the load to glycogen synthesis via direct and indirect pathways at 48-hr post-injection. For seabass, [U-13C6]glucose was accompanied by deuterated water and 2H-NMR analysis of glycogen 2H-enrichment, allowing endogenous substrate contributions to be assessed as well. For fasted seabass and seabream, 47 ± 5% and 64 ± 10% of glycogen was synthesized from the load, respectively. Direct and indirect pathways contributed equally (25 ± 3% direct, 21 ± 1% indirect for seabass; 35 ± 7% direct, 29 ± 4% indirect for seabream). In fasted seabass, integration of 2H- and 13C-NMR analysis indicated that endogenous glycerol and anaplerotic substrates contributed an additional 7 ± 2% and 7 ± 1%, respectively. In fed seabass, glucose load contributions were residual and endogenous contributions were negligible. Concluding, direct and indirect pathways contributed equally and substantially to fasting hepatic glycogen repletion from a glucose load in juvenile seabream and seabass

Effects of dietary carbohydrate on hepatic de novo lipogenesis in European seabass (Dicentrarchus labrax L.)

Farmed seabass have higher adiposity than their wild counterparts and this is often attributed to carbohydrate (CHO) feeding. Whether this reflects a reduction in fat oxidation, increased de novo lipogenesis (DNL), or both, is not known. To study the effects of high CHO diets on hepatic TG biosynthesis, hepatic TG deuterium (2H) enrichment was determined following 6 days in 2H-enriched tank water for fish fed with a no-CHO control diet (CTRL), and diets with digestible starch (DS) and raw starch (RS). Hepatic fractional synthetic rates (FSRs, percent per day-1) were calculated for hepatic TG-glyceryl and FA moieties through 2H NMR analysis. Glyceryl FSRs exceeded FA FSRs in all cases, indicating active cycling. DS fish did not show increased lipogenic potential compared to CTRL. RS fish had lower glyceryl FSRs compared with the other diets and negligible levels of FA FSRs despite similar hepatic TG levels to CTRL. DS-fed fish showed higher activity for enzymes that can provide NADPH for lipogenesis, relative to CTRL in the case of glucose-6-phosphate dehydrogenase (G6PDH) and relative to RS for both G6PDH and 6-phosphogluconate dehydrogenase. This approach indicated that elevated hepatic adiposity from DS feeding was not attributable to increased DNL

Chitosan-mediated shRNA knockdown of cytosolic alanine aminotransferase improves hepatic carbohydrate metabolism

Alanine aminotransferase (ALT) catalyses a transamination reaction that links carbohydrate and amino acid metabolism. In this study, we examined the effect of silencing cytosolic ALT (cALT) expression on the hepatic metabolism in Sparus aurata. A number of siRNA and shRNA designed to down-regulate cALT expression were validated in HEK-293 cells transfected with plasmids expressing S. aurata cALT or mitochondrial ALT (mALT) isoforms: ALT silencing significantly decreased the expression levels of S. aurata mRNA cALT1 to 62 % (siRNA) and 48 % (shRNA) of the values observed in control cells. The effect of cALT silencing was analysed in the liver of S. aurata 72 h after intraperitoneal injection of chitosan-tripolyphosphate (TPP) nanoparticles complexed with a plasmid encoding a shRNA to down-regulate cALT expression (pCpG-si1sh1). In fish fed diets with different ratio of protein to carbohydrate and treated with chitosan-TPP-pCpG-si1sh1, cALT1 and cALT2 mRNA levels significantly decreased irrespective of the diet. Consistently, ALT activity decreased in liver of treated animals. In the liver of S. aurata treated with chitosan-TPP-pCpG-si1sh1 nanoparticles, down-regulation of cALT expression increased the activity of key enzymes in glycolysis (6-phosphofructo-1-kinase and pyruvate kinase) and protein metabolism (glutamate dehydrogenase). Besides showing for the first time that administration of chitosan-TPP-pCpG-si1sh1 nanoparticles silences hepatic cALT expression in vivo, our data support that down-regulation of cALT could improve the use of dietary carbohydrates to obtain energy and spare protein catabolis

A transcriptomic approach to study the effect of long-term starvation and diet composition on the expression of mitochondrial oxidative phosphorylation genes in gilthead sea bream (Sparus aurata)

Background: The impact of nutritional status and diet composition on mitochondrial oxidative phosphorylation (OXPHOS) in fish remains largely unknown. To identify biomarkers of interest in nutritional studies, herein we obtained a deep-coverage transcriptome by 454 pyrosequencing of liver and skeletal muscle cDNA normalised libraries from long-term starved gilthead sea bream (Sparus aurata) and fish fed different diets. Results: After clean-up of high-throughput deep sequencing reads, 699,991 and 555,031 high-quality reads allowed de novo assembly of liver and skeletal muscle sequences, respectively (average length: 374 and 441 bp; total megabases: 262 and 245 Mbp). An additional incremental assembly was completed by integrating data from both tissues (hybrid assembly). Assembly of hybrid, liver and skeletal muscle transcriptomes yielded, respectively, 19,530, 11,545 and 10,599 isotigs (average length: 1330, 1208 and 1390 bp, respectively) that were grouped into 15,954, 10,033 and 9189 isogroups. Following annotation, hybrid transcriptomic data were used to construct an oligonucleotide microarray to analyse nutritional regulation of the expression of 129 genes involved in OXPHOS in S. aurata. Starvation upregulated cytochrome c oxidase components and other key OXPHOS genes in the liver, which exhibited higher sensitive to food deprivation than the skeletal muscle. However, diet composition affected OXPHOS in the skeletal muscle to a greater extent than in the liver: most of genes upregulated under starvation presented higher expression among fish fed a high carbohydrate/low protein diet. Conclusions: Our findings indicate that the expression of coenzyme Q-binding protein (COQ10), cytochrome c oxidase subunit 6A2 (COX6A2) and ADP/ATP translocase 3 (SLC25A6) in the liver, and cytochrome c oxidase subunit 5B isoform 1 (COX5B1) in the liver and the skeletal muscle, are sensitive markers of the nutritional condition that may be relevant to assess the effect of changes in the feeding regime and diet composition on fish farming

Metabolic plasticity for subcutaneous fat accumulation in a long-distance migratory bird traced by 2H2O

La comilona migratoria de cola negra (Limosa limosa) tradicionalmente utilizaba humedales naturales en la Península Ibérica para prepararse para los vuelos migratorios alimentándose principalmente en estuarios. En las últimas décadas, esta especie se ha vuelto cada vez más dependiente de los campos de arroz, confiando así en una dieta basada en plantas para alimentar. Los ácidos grasos en la dieta (FA) parecen ser determinantes para la composición de la grasa subcutánea acumulada en las aves migratorias. Aún no está claro si la plasticidad metabólica permite la modificación y / o síntesis de la FA, lo que contribuye a un perfil lipídico que permite un rendimiento migratorio exitoso. El agua deuterada se administró a las monitas de cola negra cautivas sometidas a dos dietas (larvas de mosca versus arroz) y se analizó la incorporación de deuterio (2H) en los triglicéridos subcutáneos mediante RMN. Un método de biopsia localizada recientemente desarrollado para muestrear grasa subcutánea se empleó con la posterior liberación exitosa de todas las aves en el medio silvestre. La estructura química promedio reflejó principalmente una mezcla de FA saturada y monoinsaturada de 16 y 18 carbonos, un perfil que se encuentra con frecuencia en las aves migratorias. Se observaron niveles significativamente más altos de FA poliinsaturada, así como niveles detectables de FA n-3, en aves alimentadas con larvas de mosca. El exceso de enriquecimiento con 2H en FA reveló tasas significativamente más altas de lipogénesis de novo fraccional y capacidad de desaturación de FA en aves alimentadas con arroz. Este novedoso y no letal método trazador reveló la capacidad de esta especie para alterar su metabolismo lipídico para compensar una contribución de lípidos en la dieta más deficiente. Debido a su versatilidad, la adaptación de este método a otros escenarios y / u otras especies migratorias se considera factible y rentable.The migrant black-tailed godwit (Limosa limosa) traditionally used natural wetlands in the Iberian Peninsula to prepare for migratory flights by feeding mainly in estuaries. In recent decades, this species has become increasingly dependent on rice fields, thereby relying on a plant-based diet for fuelling. Dietary fatty acids (FA) seem to be determinant to the composition of accumulated subcutaneous fat in migratory birds. It is still unclear whether metabolic plasticity allows for modification and/or synthesis of FA, contributing to a lipid profile that enables a successful migratory performance. Deuterated water was administered to captive black-tailed godwits submitted to two diets (fly larvae versus rice) and the incorporation of deuterium (2H) into subcutaneous triglycerides was analyzed by NMR. A recently developed localized biopsy method for sampling subcutaneous fat was employed with later successful release of all birds into the wild. The average chemical structure reflected mostly a mixture of saturated and monounsaturated 16- and 18-carbon FA, a profile frequently found in migrant birds. Significantly higher levels of polyunsaturated FA, as well as detectable levels of n-3 FA, were observed in fly-larvae-fed birds. Excess 2H-enrichments in FA revealed significantly higher rates of fractional de novo lipogenesis and FA desaturation capacity in rice-fed birds. This novel and nonlethal tracer method revealed the capacity of this species to alter its lipid metabolism to compensate for a poorer dietary lipid contribution. Because of its versatility, adapting this method to other scenarios and/or other migratory species is considered feasible and costeffective.• Fundação para a Ciência e Tecnologia. Beca SFRH / BPD / 90032/2012, para Iván Daniel dos Santos Martins Viegas • Fundação para a Ciência e Tecnologia. Beca SFRH / BD / 69238/2010, para Pedro Miguel Mendes Araujo • Fundação para a Ciência e Tecnologia. Beca SFRH / BD / 74228/2010, para Afonso D. Rocha • Fundação para a Ciência e Tecnologia. Beca SFRH / BPD / 91527/2012, para José Albino Alves • Fundação para a Ciência e Tecnologia. Proyecto de investigación EXCL / DTP-PIC / 0069/2012peerReviewe

The administration of chitosan-tripolyphosphate-DNA nanoparticles to express exogenous SREBP1a enhances conversion of dietary carbohydrates into lipids in the liver of Sparus aurata

In addition to being essential for the transcription of genes involved in cellular lipogenesis, increasing evidence associates sterol regulatory element binding proteins (SREBPs) with the transcriptional control of carbohydrate metabolism. The aim of this study was to assess the effect of overexpression SREBP1a, a potent activator of all SREBP-responsive genes, on the intermediary metabolism of Sparus aurata, a glucose-intolerant carnivorous fish. Administration of chitosan-tripolyphosphate nanoparticles complexed with a plasmid driving expression of the N-terminal transactivation domain of SREBP1a significantly increased SREBP1a mRNA and protein in the liver of S. aurata. Overexpression of SREBP1a enhanced the hepatic expression of key genes in glycolysis-gluconeogenesis (glucokinase and 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase), fatty acid synthesis (acetyl-CoA carboxylase 1 and acetyl-CoA carboxylase 2), elongation (elongation of very long chain fatty acids protein 5) and desaturation (fatty acid desaturase 2) as well as reduced nicotinamide adenine dinucleotide phosphate production (glucose-6-phosphate 1-dehydrogenase) and cholesterol synthesis (3-hydroxy-3-methylglutaryl-coenzyme A reductase), leading to increased blood triglycerides and cholesterol levels. Beyond reporting the first study addressing in vivo effects of exogenous SREBP1a in a glucose-intolerant model, our findings support that SREBP1a overexpression caused multigenic effects that favoured hepatic glycolysis and lipogenesis and thus enabled protein sparing by improving dietary carbohydrate conversion into fatty acids and cholesterol

Los estudios sobre la cárcel en Argentina (2012-2013)

Fil: Galvani, Iván. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina

Los estudios sobre la cárcel en Argentina (2012-2013)

Los estudios sobre la cárcel se han destacado en Argentina principalmente a partir de la revisión en código de denuncia -desde la perspectiva de DDHH- que visualizó a la población carcelaria como objeto de un Estado policial a fines de los 90. Además de trabajos penitenciaristas y testimoniales, los estudios abarcan a grandes rasgos tres grandes líneas: los trabajos de indagación histórica; los que articulan las denuncias desde los DDHH con la criminología crítica, línea que ubica la cárcel entre las dinámicas de segregación selectiva y gobierno de la excedencia; y los que recuperan la perspectiva de los actores desde estudios socioculturalistas o etnográficos. El actual aumento de investigaciones sobre la temática ha permitido tanto la reactualización de perspectivas como la articulación conceptual. Es por ello que hemos seleccionado cuatro libros que han tenido relevancia en el campo de los estudios sobre cárceles en los últimos dos años.Departamento de Sociologí

Utilization of Glycerol for Endogenous Glucose and Glycogen Synthesis in Seabass (Dicentrarchus labrax): a Potential Mechanism for Sparing Amino Acid Catabolism in Carnivorous Fish

Glycerol is a well-tolerated additive in aquafeeds. We hypothesized that in seabass, a carnivorous fish whose endogenous carbohydrate demands are mostly met by hepatic amino acid gluconeogenesis, glycerol effectively competes with these substrates for endogenous glucose and glycogen synthesis. To test this hypothesis, we injected fasted and fed juvenile seabass with an intraperitoneal 2 g.kg-1 bolus of glycerol enriched to 25% with [U-13C3]glycerol and monitored the appearance of blood glucose and hepatic glycogen 13C-isotopomers 48-hours thereafter by 13C NMR spectroscopy. This information was used to determine the fractional contribution of the glycerol load to systemic glucose appearance and liver glycogen synthesis. In 21-day fasted fish, the glycerol bolus contributed 47 ± 3% of circulating glucose appearance and 40 ± 3% of hepatic glycogen at 48-hr post-bolus. In fed fish, the glycerol bolus accounted for 17 ± 3% of circulating glucose and 3 ± 1% of hepatic glycogen at 48-hr post-polus. While the majority of glycerol was metabolized to glucose and glycogen via the canonical linear gluconeogenic pathway, a significant minority was converted to glucose and glycogen via the hepatic Krebs cycle. In fasted fish, linear gluconeogenesis accounted for 40 ± 3% of glucose appearance while the Krebs cycle route accounted for 7 ± 2%. In fed fish, linear and Krebs cycle-mediated contributions were 10 ± 2% and 6 ± 2%, respectively. These data indicate that glycerol effectively competes with endogenous precursors for hepatic gluconeogenesis in carnivorous fish thereby representing a novel mechanism for reducing the catabolic utilization of amino acids