RESUMEN

The cells involved in nutrient absorption in the small intestine of rats undergo rapid maturation during the suckling-weaning transition period, i.e., 2-4 wk after birth. During this period, the serum thyroid hormone level is increased. However, the molecular mechanisms involved in the regulation of ß-carotene 15,15'-monooxygenase 1 (BCMO1) gene expression in the small intestine remain unknown. In this study, we found that jejunal ß-carotene 15,15' dioxygenase activity and the gene expression of BCMO1 were significantly increased during this transition period between days 13 and 27 after birth. A chromatin immunoprecipitation assay revealed that di- and tri-methylation of histone H3 at lysine 4 (K4) and the binding of thyroid hormone receptor (TR) α-1 binding on the promoter/enhancer and/or transcribed regions of the BCMO1 gene were enhanced from the earlier stage of weaning (i.e., 20 d after birth), prior to an enhancement of the acetylation of histone H3 and the binding of coactivator (SRC-1 and CBP) to the promoter/enhancer and/or transcribed regions of the BCMO1 gene, which was apparent at 27 d after birth. These results suggest that histone H3 K4 methylation and TRα-1 binding on the BCMO1 gene during the suckling-weaning transient period in rats predisposes to subsequent coactivator recruitment and histone H3 acetylation on the gene.

Asunto(s)

Histonas/metabolismo , Lisina/metabolismo , Destete , beta-Caroteno 15,15'-Monooxigenasa/metabolismo , Acetilación , Animales , Animales Lactantes , Inmunoprecipitación de Cromatina , Regulación de la Expresión Génica , Histonas/genética , Yeyuno/metabolismo , Metilación , Regiones Promotoras Genéticas , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores alfa de Hormona Tiroidea/genética , Receptores alfa de Hormona Tiroidea/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , beta-Caroteno 15,15'-Monooxigenasa/genética

RESUMEN

Trace elements (TEs) and stable isotope ratios (delta(15)N and delta(13)C) were analyzed in fish from deep-water of the Sulu Sea, the Celebes Sea and the Philippine Sea. Concentrations of V and Pb in pelagic fish from the Sulu Sea were higher than those from the Celebes Sea, whereas the opposite trend was observed for delta(13)C. High concentrations of Zn, Cu and Ag were found in non-migrant fish in deep-water, while Rb level was high in fish which migrate up to the epipelagic zone, probably resulting from differences in background levels of these TEs in each water environment or function of adaptation to deep-water by migrant and non-migrant species. Arsenic level in the Sulu Sea fish was positively correlated with delta(15)N, indicating biomagnification of arsenic. To our knowledge, this is the first study on relationship between diel vertical migration and TE accumulation in deep-water fish.

Asunto(s)

Isótopos de Carbono/análisis , Ecosistema , Peces/metabolismo , Isótopos de Nitrógeno/análisis , Oligoelementos/análisis , Oligoelementos/metabolismo , Migración Animal/fisiología , Animales , Contaminación de Alimentos/análisis , Geografía , Humanos , Océanos y Mares

RESUMEN

Trace elements (22) and stable isotope ratios (delta15N and delta13C) were analyzed in marine organisms from shallow (SW) and deep-water (DW) of the East China Sea to understand biomagnification and prey source of trace elements. In the benthic marine organisms from DW, delta15N values were negatively correlated with Ba, Cu, Ag, Mo, Sr, As, and Co concentrations. This may be due to the specific accumulation in lower trophic animals and/or the biodilution through the food web in DW. Relationships between delta15N and concentrations of Co, Cr, Bi, and Tl in fish and Ag, Bi, V, Hg, and Tl in crustaceans showed positive correlations, suggesting that trophic position was affecting the concentrations of those elements in phyla, with higher trophic animals retaining higher concentrations than the lower trophic animals. Positive correlations between delta13C and Rb were observed in marine organisms. Therefore, Rb may be a possible substitute of delta13C as tracer of prey source in the East China Sea although further investigation is required.

Asunto(s)

Cadena Alimentaria , Isótopos/análisis , Oligoelementos/análisis , Contaminantes Químicos del Agua/análisis , Animales , China , Crustáceos , Monitoreo del Ambiente/métodos , Peces , Contaminación de Alimentos , Invertebrados , Dosis Máxima Tolerada , Océanos y Mares , Zooplancton

RESUMEN

Fatty acids in milk are thought to play an important role in intestinal maturation and gene expression in the rat small intestine during the suckling-weaning period. In the present study, we determined the jejunal mRNA level of the cAMP-response-element-binding-protein-binding protein (CBP)/p300, which is one of the chromatin remodelling factors and regulates histone acetylation, during the postnatal period in rats. The mRNA level of CBP/p300 was high during the suckling and middle of the weaning period (day 5 to 20) and then declined sharply to a low level at the end of the weaning period and after weaning. In situ hybridisation also showed that CBP/p300 mRNA levels in the villus as well as the basal membrane clearly decreased after weaning. Rat pups at age 17 d, weaned to a high-fat diet, showed higher levels of CBP/p300 mRNA than those weaned to a low-fat diet. Oral administration of caprylic acid, oleic acid and linoleic acid, which are major fatty acid components in milk, induced jejunal CBP/p300 gene expression. The present results suggest that fatty acids in components of milk enhance expression of the CBP/p300 genes in the small intestine.

Asunto(s)

Proteína de Unión a Elemento de Respuesta al AMP Cíclico/biosíntesis , Grasas de la Dieta/farmacología , Proteína p300 Asociada a E1A/biosíntesis , Ácidos Grasos/farmacología , Leche/química , Animales , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/genética , Proteína p300 Asociada a E1A/genética , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Hibridación in Situ/métodos , Yeyuno/crecimiento & desarrollo , Yeyuno/metabolismo , Lactancia , Unión Proteica , ARN Mensajero/genética , Ratas , Ratas Sprague-Dawley , Destete

RESUMEN

Tributyltin (TBT) is organotin compound that is toxic to aquatic life ranging from bacteria to mammals. This study examined the concentration of TBT in sediment from and near the Mekong River and the distribution of TBT-resistant bacteria. TBT concentrations ranged from <2.4 to 2.4 ng/g (dry wt) in river sediment and <2.4-15 ng g(-1) (dry wt) in harbor sediment. Viable count of total bacteria ranged from 2.0 x 10(4) to 1.4 x 10(7)cfu/g, and counts of TBT-resistant bacteria ranged <1.0 x 10(2) to 2.5 x 10(4)cfu/g. The estimated occurrence rate of TBT-resistant bacteria ranged from <0.01 to 34% and was highest in upstream sites in Cambodia. The occurrences of TBT in the sediment and of TBT-resistant bacteria were unrelated, and chemicals other than TBT might induce TBT resistance. TBT-resistant bacteria were more abundant in the dry season than in the rainy season. Differences in the selection process of TBT-resistant bacteria between dry and rainy seasons were examined using an advection-diffusion model of a suspended solid (SS) that conveys chemicals. The estimated dilution-diffusion time over a distance of 120 km downstream from a release site was 20 days during dry season and 5 days during rainy season, suggesting that bacteria at the sediment surface could be exposed to SS for longer periods during dry season.

Asunto(s)

Farmacorresistencia Bacteriana , Sedimentos Geológicos , Ríos , Compuestos de Trialquiltina/análisis , Microbiología del Agua , Contaminantes Químicos del Agua/análisis , Recuento de Colonia Microbiana , Monitoreo del Ambiente , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiología , Japón , Modelos Químicos , Ríos/química , Ríos/microbiología

RESUMEN

During second and third weeks after birth in rats, serum thyroid hormone level is elevated. In this study, we investigated the jejunal expression of thyroid hormone receptor (TR) alpha in developing rats. The TRalpha-1 mRNA level and TRalpha-1/TRalpha-2 mRNA ratio increased two-fold from 5 to 13 days after birth. This high level of TRalpha-1 mRNA was maintained until 20 days and then decreased to the basal level by the end of weaning period at 27 days; however, the level of TRalpha-2 mRNA remained unchanged throughout the developmental period. The increase in the TRalpha-1/TRalpha-2 mRNA ratio from 5 to 13 days was accompanied by an initial rise in the levels of mRNA for hexose transporters in the jejunum. Administration of T(3) during the suckling period (8-13 days) caused a 50% increase in the TRalpha-1/TRalpha-2 mRNA ratio, while administration of T(3) on days 12-17 and days 16-21, but not on days 22-27, caused a two to four-fold increase in the levels of mRNA for hexose transporters. These results suggest that a transient variation in the TRalpha-1/TRalpha-2 expression ratio is closely related to the critical period of thyroid hormone responsiveness for hexose transporters expression in the developing rat jejunum.

Asunto(s)

Regulación del Desarrollo de la Expresión Génica , Yeyuno/metabolismo , Proteínas de Transporte de Monosacáridos/metabolismo , Receptores alfa de Hormona Tiroidea/metabolismo , Hormonas Tiroideas/metabolismo , Animales , Animales Recién Nacidos , Animales Lactantes , Northern Blotting , Células CACO-2 , Ensayo de Cambio de Movilidad Electroforética , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Transportador de Glucosa de Tipo 2/metabolismo , Transportador de Glucosa de Tipo 5/metabolismo , Humanos , Mucosa Intestinal/metabolismo , Intestino Delgado/crecimiento & desarrollo , Intestino Delgado/metabolismo , Yeyuno/efectos de los fármacos , Yeyuno/embriología , Proteínas de Transporte de Monosacáridos/genética , Regiones Promotoras Genéticas , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Transportador 1 de Sodio-Glucosa/metabolismo , Receptores alfa de Hormona Tiroidea/genética , Hormonas Tiroideas/farmacología , Factores de Tiempo , Activación Transcripcional , Transfección , Triyodotironina/metabolismo , Destete

RESUMEN

Fatty acids in milk are thought to play an important role in intestinal maturation and gene expression in the postnatal small intestine. In this study, we determined the jejunal mRNA levels, in rats, of peroxisome proliferator-activated receptor alpha (PPARalpha) and PPARdelta which are nuclear receptors for fatty acids. We also measured expression of their target genes during the postnatal period, namely liver type fatty acid-binding protein (L-FABP) and cellular retinol-binding protein, type II (CRBPII). The mRNA levels of PPARalpha, L-FABP and CRBPII, but not PPARdelta, gradually increased during the suckling period and then sharply declined to a low level at the end of the weaning period. Rat pups at 17 d of age, weaned to a high-fat diet, showed significantly greater mRNA levels of PPARalpha, L-FABP and CRBPII than those weaned to a low-fat diet. Oral administration of PPARalpha ligand, WY14,643 during four consecutive days of the weanling period caused a parallel increase in the mRNA levels of PPARalpha, L-FABP and CRBPII genes. Furthermore, caprylic acid and oleic acid, which are major components of fatty acids in milk, induced jejunal PPARalpha, L-FABP and CRBPII gene expression. Our results suggest that fatty acids in milk may play a pivotal role in maintaining an enhanced level of expression of L-FABP and CRBPII genes in the small intestine, presumably by acting as inducers of PPARalpha gene expression.

Asunto(s)

Proteínas de Unión a Ácidos Grasos/metabolismo , Ácidos Grasos/metabolismo , Leche/metabolismo , PPAR alfa/metabolismo , Vitamina A/metabolismo , Vitaminas/metabolismo , Animales , Animales Lactantes , Citosol/metabolismo , Proteínas de Unión a Ácidos Grasos/genética , Ácidos Grasos/farmacología , Femenino , Expresión Génica/efectos de los fármacos , Expresión Génica/fisiología , Yeyuno/fisiología , PPAR alfa/genética , PPAR delta/genética , PPAR delta/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Proteínas Celulares de Unión al Retinol/genética , Proteínas Celulares de Unión al Retinol/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiología

Asunto(s)

Monitoreo del Ambiente , Peces , Hidrocarburos Clorados/análisis , Plaguicidas/análisis , Bifenilos Polibrominados/análisis , Contaminantes Químicos del Agua/análisis , Animales , Océanos y Mares , Filipinas

RESUMEN

Retinoic acid (RA) plays important roles in cellular differentiation and proliferation in various tissues including the liver. To explore a possible role of RA in the postnatal development of hepatic function, we analyzed RA-generation enzyme activity and the RA-related hepatic gene expressions in the suckling and weaning rats. At 5 days after birth, retinal dehydrogenase (RALDH) activity in the liver was relatively high. Its activity decreased by 70% until day 17, and then it gradually increased to a high level by the completion of weaning period. Northern blot analysis showed that RALDH2 mRNA levels decreased in the suckling period, whereas RALDH1 mRNA levels increased in the weaning period. Retinoid X receptor alpha (RXRalpha) mRNA levels increased in the suckling period and attained to a higher level at 17 days after birth. Retinoic acid receptor alpha (RARalpha) mRNA level showed only a slight and temporary increase on day 13. The mRNA levels of hepatocyte nuclear factors (HNF-4 and HNF-1alpha) exhibited parallel increases around suckling-weaning period, and the transcript levels of albumin, a typical target gene of the hepatocyte nuclear factors, increased during the suckling-weaning transition period. Electrophoretic mobility shift assay using a putative nuclear receptor-binding element on rat HNF-1 alpha gene revealed that HNF-4 homodimer, but not RXRalpha homodimer, bound to this element. These results suggest that postnatal expressions of hepatocyte-specific genes might be up-regulated by retinoid receptors, which may be related with the alterations of RALDH expression during postnatal development in the liver.

Asunto(s)

Aldehído Oxidorreductasas/metabolismo , Proteínas de Unión al ADN , Regulación de la Expresión Génica , Isoenzimas/metabolismo , Hígado/metabolismo , Proteínas Nucleares , Receptores de Ácido Retinoico/metabolismo , Aldehído Oxidorreductasas/genética , Animales , Animales Recién Nacidos , Animales Lactantes , Dimerización , Femenino , Factor Nuclear 1 del Hepatocito , Factor Nuclear 1-alfa del Hepatocito , Factor Nuclear 1-beta del Hepatocito , Factor Nuclear 4 del Hepatocito , Isoenzimas/genética , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Unión Proteica , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores de Ácido Retinoico/genética , Retinal-Deshidrogenasa , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Tretinoina/metabolismo , Destete