Effects of atosiban on stress-related neuroendocrine factors

Atosiban, an oxytocin/vasopressin receptor antagonist, is used to decrease preterm uterine activity. The risk of preterm delivery is undoubtedly associated with stress, but potential side effects of atosiban on neuroendocrine functions and stress-related pathways are mostly unknown. These studies were designed to test the hypothesis that the chronic treatment of rats with atosiban modulates neuroendocrine functions under stress conditions. Male rats were treated (osmotic minipumps) with atosiban (600 μg/kg per day) or vehicle and were restrained for 120 min/day for 14 days. All animals were treated with a marker of cell proliferation 5-bromo-2-deoxyuridine. Anxiety-like behavior was measured using an elevated plus-maze. Treatment with atosiban failed to modify plasma concentrations of the stress hormones ACTH and corticosterone, but led to a rise in circulating copeptin. Atosiban increased prolactin levels in the non-stressed group. Oxytocin receptor mRNA levels were increased in rats exposed to stress. Treatment with atosiban, in both control and stressed animals, resulted in a decrease in oxytocin receptor gene expression in the hypothalamus. No changes were observed in vasopressin receptor 1A and 1B gene expression. The decrease in hippocampal cell proliferation induced by stress exposure was not modified by atosiban treatment. This study provides the first data, to our knowledge, revealing the effect of atosiban on gene expression of oxytocin receptors in the brain. Atosiban-induced enhancement of plasma copeptin indicates an elevation in vasopressinergic tone with potential influence on water-electrolyte balance.

Differential gene expression between the porcine morula and blastocyst

The survival and development of pre-implantation embryos are determinant factors affecting the outcome of animal reproduction. It is essential to transfer the expression of the genetic material from maternal sources, that is the ovum to the zygote before implantation to ensure successful development. Differentiation and transformation of blastomeres initiated during the morula and blastocyst stages is an important step of the embryonic development prior to implantation. We collected morula and early blastocyst samples from pure-bred Landrace pigs in vivo to study the differential gene expression patterns at these two stages. Total RNA was extracted from individual embryos and two rounds of amplification were employed. Two micrograms of antisense RNA, targets, were prepared and hybridized with each of four custom made oligo microarrays representing 24,000 porcine genes. The analyses of replicate hybridizations showed that among the 24,000 genes, 162 genes were expressed fivefold or greater in the morula compared to early blastocysts and 2126 genes were expressed fivefold or greater in early blastocysts compared to the morula. Of these differentially expressed genes, 1429 genes were functionally annotated with related human Gene Ontology terms. In addition to basic metabolic processes, genes related to signal transduction, transportation and cell differentiation were found in both stages and were up-regulated as embryo development proceeded. Real time polymerase chain reaction was utilized to quantify 12 genes differentially expressed in the 2 embryonic stages and validated the reliability of major evidences shown in microarrays. In conclusion, we have obtained a preliminary landscape of genes differentially expressed during the transition from morula to early blastocysts in pigs and showed a generally increased transcriptional activity, perhaps in preparation for implantation. Our results provide an opportunity to study the functions of these genes in relation to the development and survival of pre-implantation porcine embryos.

Visfatin regulates genes related to lipid metabolism in porcine adipocytes

Visfatin is a visceral adipose tissue-specific adipocytokine that plays a positive role in attenuating insulin resistance by binding to the insulin receptor. Visfatin has been suggested to play a role in the regulation of lipid metabolism and inflammation; however, the mechanism remains unclear. We investigated the effects of visfatin on the regulation of gene expression in cultured porcine preadipocytes and differentiated adipocytes. In preadipocytes, the mRNA abundance of lipoprotein lipase and PPARgamma were significantly increased by visfatin or insulin treatment after 8 d (all P < 0.05). In the presence of insulin, the mRNA abundance of adipocyte fatty acid-binding protein was 24.7-fold greater than in the untreated group (P < 0.05), whereas visfatin alone had no effect on adipocyte fatty acid-binding protein mRNA abundance. Adipocyte differentiation was induced by insulin treatment for 8 d. In differentiated porcine adipocytes, exposure to insulin or visfatin for 24 h increased (P < 0.05) fatty acid synthase mRNA abundance but had no effect on the expression of sterol regulatory element binding-protein 1c mRNA. We also found a 5.8-fold upregulation of IL-6 expression in porcine adipocytes after 24 h of treatment with visfatin (P < 0.05). These results demonstrated that visfatin upregulated lipoprotein lipase expression in preadipocytes, potentially facilitating lipid uptake, and increased the gene expression of fatty acid synthase in differentiated adipocytes to potentially enhance lipogenic activity. Furthermore, visfatin can upregulate IL-6 expression in differentiated porcine adipocytes. The information presented in this study provides insights into the roles of visfatin in lipid metabolism in pigs.

Porcine peroxisome proliferator-activated receptor delta mediates the lipolytic effects of dietary fish oil to reduce body fat deposition

Peroxisome proliferator-activated receptor delta promotes fatty acid catabolism and energy expenditure in skeletal muscle and adipose tissues. A ligand for PPARdelta is required to activate PPARdelta function. Polyunsaturated fatty acids are potential ligands for PPARdelta activation. The current experiment was designed to determine the potential for PUFA, particularly from dietary fish oil, to activate porcine PPARdelta in vivo. Transgenic mice were generated to overexpress porcine PPARdelta in the adipose tissue. Mice were fed a high-saturated fat (13% beef tallow), or high-unsaturated fat (13% fish oil) diet, or a diet containing 4 mg/kg of a PPARdelta ligand (L165041) for 4 mo. Compared with beef tallow feeding, fish oil feeding reduced fat mass and decreased (P < 0.05) plasma triacylglycerol and FFA concentrations in the transgenic mice. Adipose tissue expression of genes involved in adipogenesis (i.e., lipoprotein lipase and adipocyte fatty acid-binding protein) was decreased in transgenic mice fed fish oil or the PPARdelta ligand. In the same mice, expression of the lipolytic gene, hormone-sensitive lipase was increased (P < 0.05). Fish oil feeding also stimulated expression of genes participating in fatty acid oxidation in the liver of transgenic mice compared with wild-type mice. Overall, these results indicate that PUFA may serve as natural and effective regulators of lipid catabolism in vivo and many of these effects may be generated from activation of PPARdelta.

Abundantly expressed hepatic genes and their differential expression in liver of prelaying and laying geese

Geese have a short egg-laying period and a low egg production rate. To induce and maintain egg laying, genes related to generating hepatic lipid for yolk deposition should be adequately expressed. Liver mRNA from 6 laying geese was extracted and used for construction of a full-length enriched cDNA library. About 2,400 clones containing gene sequences were determined and National Center for Biotechnology Information Gallus gallus Gene Index databases were used to compare and analyze these sequences. Ten highly expressed genes were selected to determine the differential expression between laying and prelay goose liver. Tissue distribution data showed that very low density apolipoprotein II, liver type fatty acid binding protein, vitellogenin I, and vitellogenin II transcripts were specifically expressed in the liver of laying geese. Ovoinhibitor, preproalbumin, alpha-2-hs-glycoprotein, and vitamin D binding protein mRNA were highly expressed in the liver and to a lesser extent in other tissues. Ovotransferrin mRNA was expressed in liver, ovary, oviduct, shell gland, brain, and adipose tissues. The concentration of transthyretin mRNA was high in the liver and brain. The mRNA concentrations of liver type fatty acid binding protein, alpha-2-hs-glycoprotein, and transthyretin in the livers of laying and prelay geese were not different. The concentrations of hepatic ovotransferrin, ovoinhibitor, preproalbumin, very low density apolipoprotein II, vitellogenin I, vitellogenin II, and vitamin D binding protein mRNA were higher in the liver of laying geese than in prelay geese, suggesting that these genes may be involved in laying function or lipid metabolism related to egg formation.

Docosahexaenoic acid regulates adipogenic genes in myoblasts via porcine peroxisome proliferator-activated receptor gamma

The nuclear transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma) triggers adipocyte differentiation by regulating lipogenic genes. A ligand for PPARgamma is necessary to activate PPARgamma function. Fatty acids are potential ligands for PPARgamma activation. The current experiment was designed to determine the potential for individual fatty acids to activate porcine PPARgamma ectopically expressed in myoblasts. The expression of adipocyte fatty acid binding protein (aP2) and adiponectin in myoblasts stably expressing porcine PPARgamma was increased when docosahexaenoic acid (DHA) was added to the adipogenic medium. The response was positively related to DHA concentration and suggests that DHA may bind to and activate porcine PPARgamma, leading to increased expression of aP2 and adiponectin. The conditioned media collected from myoblasts expressing PPARgamma between d 3 and 6 or between d 6 and 9, but not DHA itself, activated the aP2 gene promoter-driven luciferase activity. These results suggest that a metabolite of DHA is the ligand binding to and activating porcine PPARgamma. The metabolite and pathway for its production are currently unknown.

Fasting regulates the expression of adiponectin receptors in young growing pigs

Adiponectin is an adipocyte-derived hormone that can improve insulin sensitivity. Its functions in regulating glucose utilization and fatty acid metabolism in mammals are mediated by 2 subtypes of adiponectin receptors (AdipoR1 and AdipoR2). This study was conducted to determine the effect of fasting on the expression of adiponectin and its receptors. The expression of adiponectin was not affected in s.c. adipose tissue, but adiponectin expression increased in visceral adipose tissue after fasting. In contrast, expression of both AdipoR mRNA was increased in the liver and s.c. adipose tissue of 24-h-fasted pigs compared with fed pigs, but the mRNA in muscle and visceral adipose tissue was not affected by fasting. A third putative adiponectin receptor, T-cadherin, was cloned and the mRNA expression was determined. T-Cadherin has been recognized to act as a vascular adiponectin receptor in vascular endothelial and smooth muscle cells. Our data showed that the expression of T-cadherin was decreased in the muscle of fasted pigs, suggesting that the expression of T-cadherin can be regulated by feeding status. In summary, in young pigs, adiponectin mRNA was up-regulated by fasting in visceral, but not s.c., adipose tissue, whereas AdipoR1 and AdipoR2 mRNA were increased in s.c., but not visceral, adipose tissue. The adiponectin receptor, T-cadherin, was expressed in s.c. and visceral adipose tissue and in muscle, but only muscle mRNA expression was decreased by fasting.

Porcine peroxisome proliferator-activated receptor gamma induces transdifferentiation of myocytes into adipocytes

Peroxisome proliferator-activated receptor gamma2 (PPARgamma) is a nuclear transcription factor that regulates adipocyte differentiation and lipogenic genes during adipogenesis. The activity of rodent PPARgamma is regulated by phosphorylation of serine 112. The current experiment was designed to study the ability of porcine PPARgamma to stimulate transdifferentiation of myoblasts to adipocytes by overexpressing wild-type PPARgamma or mutated PPARgamma (serine 112 was mutated to alanine) in mouse myoblast cells. The expression of adipogenic marker genes (adipocyte fatty acid binding protein, lipoprotein lipase, and glycerol-3 phosphate dehydrogenase) in cells stably expressing mutated porcine PPARgamma was greater than in cells with wild-type PPARgamma, indicating that the mutated PPARgamma has greater adipogenic capability than the wild-type PPARgamma. Under treatment with a ligand, both wild-type and mutant porcine PPARgamma-expressing C2C12 myoblasts differentiated into adipocytes in 10 d. The expression of myogenic marker genes (myogenin, myogenic regulatory factor-4) was suppressed in cells transfected with the mutated PPARgamma or wild-type PPARgamma. Moreover, wild-type and mutant PPARgamma were able to inhibit myogenesis without addition of a ligand. Our results suggest that porcine wild-type PPARgamma and mutated PPARgamma can both convert myoblast cells into adipocytes, and also that the ability to transdifferentiate was greater in cells containing the mutated PPARgamma than in cells containing the wild-type PPARgamma. Therefore, the existence of serine 112 in PPARgamma may have a role in regulating adipocyte differentiation.

Abundantly expressed genes in pig adipose tissue: an expressed sequence tag approach

Adipose tissue plays a critical role in metabolism, storage, and release of fatty acids in mammals. Construction of a full-length cDNA library is an effective way to understand the functional expression of genes in adipose tissue, and in addition, novel genes for further research can be found in the library. In this study, adipose tissue RNA was extracted from three 18-mo-old Lee-Sung pigs. The mRNA was isolated, reverse transcribed, and used to construct a cDNA library. After transformation, 2,880 clones were selected and sequenced. Cluster analysis was performed, and the assembled contig of each cluster was subjected to search against DNA sequences in the nucleotide databases (NCBINR/TIGRGI). These sequences were clustered into 1,527 unique sequences; 80% of the sequences were categorized as known genes, and 20% of the sequences were categorized as unknown genes. In this adipose tissue cDNA library, approximately 16% of the genes contained full-length sequences with start and stop codons. Gene ontology analysis was performed to indicate the possible functions of these genes. Genes associated with mitochondrial function were abundant and represented 10% of the total. Several fatty acid transport genes and stearoyl coenzyme A desaturase were among the most abundant genes expressed. Tissue distribution of several abundant genes was analyzed by northern analysis, and many of these genes were transcribed in porcine adipose tissue in high copy number. Our full-length sequence data and tissue distribution data can be used to decipher the functional roles exhibited by the adipocyte under various perturbations via endocrine, environmental, genetic, nutritional, pharmacological, or physiological manipulations.

Ectopic expression of porcine peroxisome proliferator-activated receptor δ regulates adipogenesis in mouse myoblasts1

Peroxisome proliferator-activated receptor gamma (PPARgamma) plays a critical role in regulating adipogenesis. The expression of peroxisome proliferator-activated receptor delta (PPARdelta) precedes that of PPARgamma during adipocyte differentiation in rodents. The current experiment was designed to study the function of porcine PPARdelta and the interaction of PPARdelta and PPARgamma in adipocyte differentiation. Inhibition of myogenesis was observed in mouse myoblasts expressing porcine PPARdelta, similar to myoblasts expressing PPARgamma. Treatment of myoblasts expressing PPARdelta with ligands for both PPARdelta and PPARgamma enhanced lipogenesis and adipogenesis to a greater extent than treatment with a PPARgamma ligand alone, suggesting that both genes were involved in regulating lipogenesis and adipogenesis. The ability to transdifferentiate myoblasts into adipocytes was decreased in myoblasts coexpressing PPARdelta with either wild type or mutated PPARgamma (Ser 112 was mutated to Ala; the mutated PPARgamma is more active than the wild type) compared with myoblasts expressing PPARgamma alone. Adipocyte differentiation in myoblasts coexpressing PPARdelta and mutated PPARgamma was greater than in myoblasts coexpressing PPARdelta and wild type PPARgamma, confirming that Ser 112 is important for the function of PPARgamma. Taken together, our results demonstrate that overexpression of PPARdelta inhibits myotube formation and also enhances adipocyte differentiation. However, the complexity and interaction of PPARdelta and PPARgamma in adipogenesis are not clearly understood.

The differential expression of hepatic genes between prelaying and laying geese

Suppression subtractive hybridization was used to detect differential expression of genes in the livers of laying and prelaying geese. Liver tissues from prelaying and laying geese were dissected for mRNA extraction. The cDNA, reverse transcribed from liver mRNA of prelaying geese, was subtracted from the cDNA generated from the laying geese (forward subtraction). Five hundred seventy-six clones with possible differentially expressed gene fragments were observed by forward subtraction hybridization. After differential screening using the reverse and forward subtraction cDNA, 164 clones were subjected to gene sequence determination and further analysis. Using Northern analysis, 5 known and 8 unknown genes were shown to be highly expressed in the livers of laying geese compared with prelaying geese. Vitellogenin I, apoVLDL-II, ethanolamine kinase, G-protein gamma-5 subunit, and leucyl-tRNA synthase were highly expressed in the livers of laying geese compared with that from the prelaying geese (P<0.05). The expression of these known genes suggests that their function in the liver of laying geese is primarily involved in lipid and lipoprotein metabolism. Several of these differentially expressed genes were found to be responsive to estrogen stimulation, confirming the involvement of these genes in the egg-laying function of the goose.

Expressed transcripts associated with high rates of egg production in chicken ovarian follicles

The purpose of this study was to characterize differentially expressed transcripts associated with varying rates of egg production in Taiwan country chickens. Ovarian follicles were isolated from two strains of chicken which showed low (B) or high (L2) rates of egg production, then processed for RNA extraction and cDNA library construction. Three thousand and eight forty clones were randomly selected from the cDNA library and amplified by PCR, then used in microarray analysis. Differentially expressed transcripts (P<0.05, log(2)> or = 1.75) were sequenced, and aligned using GenBank. This analysis revealed 20 non-redundant sequences which corresponded to known transcripts. Eight transcripts were expressed at a higher level in ovarian tissue prepared from chicken strain B, and 12 transcripts were expressed at a higher level in L2 birds. These differential patterns of expression were confirmed by semi-quantitative RT-PCR. We show that transcripts of cyclin B2 (cycB2), ferritin heavy polypeptide 1 (FTH1), Gag-Pol polyprotein, thymosin beta4 (TB4) and elongation factor 1 alpha1 (EEF1A1) were enriched in B strain ovarian follicles. In contrast, thioredoxin (TXN), acetyl-CoA dehydrogenase long chain (ACADL), inhibitor of growth family member 4 (ING4) and annexin II (ANXA2) were expressed in at higher levels in the L2 strain. We suggest that our approach may lead to the isolation of effective molecular markers that can be used in selection programs in Taiwan country chickens.

The effect of dietary docosahexaenoic acid on the expression of lipogenic genes in broilers

The objectives of this work were to determine the effects of dietary fungal docosahexaenoic acid (DHA) on tissue DHA concentration and lipogenic gene expression in broilers. A fungal (SR-21) meal product containing 31.5% total fat and 32.7% DHA (% of total fatty acids) was fed to chicken broilers at 0, 1, or 3% for 3 weeks. A diet with 1% DHA oil (containing 40% DHA) was also fed to chicken broilers as a positive control. Dietary fungal meal supplementation (3%) improved daily weight gain, food intake, and feed conversion ratio. The fungal meal supplementation increased dietary DHA content and consequently increased the DHA content in plasma, breast muscle (Pectoralis major), and livers in the broilers. The plasma triacylglycerol concentration was decreased by the supplementation of dietary DHA. The data indicate that the dietary DHA treatment modified certain aspects of the lipid metabolism, especially pathways related to triacylglycerol synthesis. Indeed, both the 1% DHA oil and 3% fungal meal treatments decreased the hepatic lipogenic transcription factor sterol regulatory element binding protein 1 (SREBP1) mRNA relative abundance, suggesting that dietary DHA supplementation decreases SREBP1 gene functions. The relative mRNA abundance of the de novo fatty acid synthesis genes, fatty acid synthase and acetyl coenzyme A carboxylase, was reduced by 1% DHA oil and 3% fungal meal treatments, suggesting that dietary DHA supplementation decreases lipogenesis in the livers of the broilers. Taken together, the fungal meal is a suitable dietary supplement to increase tissue DHA content and reduce the expression of hepatic lipogenic genes in broilers.

The Expression of Pituitary Gland Genes in Laying Geese

The purpose of this study was to detect differential expression of genes in the pituitary gland in laying geese by suppression subtractive hybridization (SSH). Pituitary glands from prelaying and laying geese were dissected for mRNA extraction. The cDNA from pituitary glands of prelaying geese was subtracted from the cDNA from the pituitary glands of laying geese (forward subtraction); the reverse subtraction was also performed. We screened 384 clones with possible differentially expressed gene fragments by differential screening. Sixty-five clones from the differential screening results were subjected to gene sequencing and further analysis. We found that at least 19 genes were highly expressed in the pituitary glands of laying geese compared with prelaying geese. Among these, 6 genes (including 4 novel genes) were confirmed by virtual Northern analysis. We found that prolactin and visinin-like protein were highly expressed in the pituitary glands of laying geese compared with prelaying geese (P < 0.05). Further investigation is needed to demonstrate specific functions of the novel genes discovered in the current study.

Cloning and expression of porcine adiponectin and adiponectin receptor 1 and 2 genes in pigs

In mice, adiponectin receptors (AdipoR) have been found to mediate the effect of adiponectin in muscle and liver in regulation of glucose and fatty acid metabolism. The purposes of this study were to clone these receptors from pig tissues by reverse transcription PCR using mRNA from skeletal muscle and adipose tissue and to investigate the expression of these genes in various pig tissues. Sequences of adiponectin, AdipoR1, and AdipoR2 were determined and found to be highly homologous to those of the human and mouse. The AA sequences predicted for the full-length cDNA of porcine adiponectin, AdipoR1, and AdipoR2 were similar to those of the human and mouse, ranging from 81 to 97% homology, suggesting similar functions of these genes in pigs as in other species. Transcripts for adiponectin were abundant in s.c. adipose tissue in Lee-Sung pigs and in crossbred pigs. Transcripts for AdipoR1 were abundant in heart and skeletal muscle and also detected to a lesser extent (P < 0.05) in adipose tissue, liver, and spleen of the Lee-Sung pigs. Transcripts for AdipoR2 were abundant in s.c. adipose tissue and present to a lesser extent (P < 0.05) in the liver, heart, skeletal muscle, and spleen. These results indicate that the effect of adiponectin may be mediated through these receptors in various porcine tissues. Fasting for 8 h did not have a significant effect on the expression of adiponectin and AdipoR1 mRNA, but it increased (P < 0.05) the AdipoR2 mRNA in the s.c. adipose tissue of crossbred pigs. These results indicate that the AdipoR2-mediated fatty acid oxidation may be responsible at least in part for the fasted state fatty acid oxidation in porcine adipose tissues. The successful cloning of pig adiponectin and adiponectin receptors will enhance the understanding of the involvement of these genes in regulating energy metabolism in pigs.

The expression of genes related to adipocyte differentiation in pigs1

The purpose of this study was to detect differential expression of genes related to adipocyte differentiation in pigs by suppression subtractive hybridization. Adipocytes and stromal vascular cells (a fraction containing preadipocytes) from pig adipose tissue were isolated for mRNA extraction. The cDNA from preadipocytes was subtracted from the cDNA from adipocytes. The subtracted gene fragments were cloned into pGEM-T Easy TA cloning vector. We selected 384 clones for gene sequence determination and for further analysis. These genes were subjected to a differential screening procedure to confirm the differential expression of genes between the 2 cell types. We found that at least 36 genes were highly expressed in the adipocytes compared with preadipocytes. Among these, 6 genes including 2 novel genes with the greatest differences were selected and confirmed by Northern analysis. We found that angiotensin I-converting enzyme (ACE), ataxia-telangiectasia mutated protein (ATM), calpain 1, and stearoyl coenzyme A desaturase 1 (SCD1) were highly expressed in adipocytes compared with preadipocytes (P < 0.05). The relative mRNA abundance of ACE, ATM, calpain 1, SCD1, and 2 novel genes discovered in the current study was increased at the later stages of adipocyte differentiation (P < 0.05). The results confirmed that the genes involved in lipid metabolism and adipocyte differentiation were highly expressed in porcine adipocytes. However, further investigation is needed to demonstrate specific functions of the novel genes discovered in the current study.

Schizochytrium limacinum SR-21 as a source of docosahexaenoic acid: optimal growth and use as a dietary supplement for laying hens

Culture conditions for the marine fungus Schizochytrium limacinum SR-21 (SR-21) to produce microbial docosahexaenoic acid (DHA) were evaluated, and the practicality of using this fungus product as a dietary supplement for laying Leghorn hens was investigated. The data showed that the cultured fungus produced high biomass and DHA. It generated 584 mg DHA/L of culture at the end of a 6-day culture. The fungus grew better at 25ºC than at 20ºC or 30ºC. With an increase in glucose concentration from 1% to 5% in the culture medium, biomass and DHA production were enhanced. A 6% glucose treatment reduced the biomass production compared with 5% glucose. A bioreactor was used to mass-produce SR-21. The biomass was increased from 1.12 g/L at Day 0 to 12 g/L at Day 4. We established optimal culture conditions of 5% glucose, 2% sea salt, and 1% yeast extract for SR-21. Three concentrations of dried fungal meal (0, 1, or 3% in the diet) were fed to birds over a 3-week period. There were no negative effects of 1 and 3% dietary SR-21 on egg production, egg weight, and egg yolk weight. The DHA content of yolk was increased by the dietary supplementation with the fungal meal both in the 1 and 3% treatments. Dietary fungal meal treatments increased the DHA concentrations of liver and plasma. However, dietary DHA enrichment had no effect on the expression of hepatic lipogenic genes in laying hens.

Effect of docosahexaenoic acid and arachidonic acid on the expression of adipocyte determination and differentiation-dependent factor 1 in differentiating porcine adipocytes1

Adipocyte determination and differentiation-dependent factor 1 (ADD1) drives the expression of several lipogenic genes in mammals. Polyunsaturated fatty acids decrease ADD1 mRNA abundance in differentiating porcine adipocytes. The current study was designed to explore the mechanisms by which PUFA inhibit the expression of ADD1 in porcine adipocytes. Porcine preadipocytes were differentiated for 24 h with 0 or 100 microM of docosahexaenoic acid (DHA) and mixtures of different concentrations of antioxidants to investigate the effect of DHA and antioxidants on the ADD1 mRNA abundance. We found the relative mRNA abundance was decreased by the addition of 100 microM DHA to the medium for porcine differentiating adipocytes, and adding an antioxidant mixture to the medium prevented part of the decrease in ADD1 mRNA abundance. These data suggest that DHA decreased the steady-state transcription factor ADD1 mRNA through a mechanism related to fatty acid peroxidation. Indeed, adding 7.5 microM vitamin E (a natural antioxidant) also restored the concentrations of ADD1 and fatty acid synthase mRNA, which were decreased by DHA treatment; however, the DHA or the antioxidant treatment did not change the expression of antioxidation genes (superoxide dismutase 1 and glutathione peroxidase 1) in porcine stromal vascular cells. When supplemented with the eicosanoid synthesis pathway inhibitors, the inhibition of the expression of ADD1 by arachidonic acid was partially recovered. These results suggest that the mechanism by which PUFA decrease ADD1 mRNA is due to the metabolic product of eicosanoids and peroxidation of these PUFA.

Cloning and expression of the genes associated with lipid metabolism in Tsaiya ducks

Sterol regulatory element binding protein 1 (SREBP1) drives the expression of several lipogenic genes, whereas SREBP2 dictates the expression of every gene involved in cholesterolgenesis in mammals. In the current study, we cloned the cDNA fragments for SREBP1, SREBP2, fatty acid synthase (FAS), 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase), and very low density apolipoprotein-II (apoVLDL-II), the genes associated with lipid metabolism. Fifteen ducks immediately before the first egg was laid (18 wk old) and 15 ducks from the same population at an egg production rate of 80% were killed. Total RNA was extracted from liver and used to amplify the targeted genes by reverse transcription-PCR and screening of a cDNA library. The sequence data showed that Tsaiya duck SREBP1, SREBP2, FAS, and HMG-CoA reductase were highly homologous to that of chicken. Tsaiya duck SREBP1 mRNA was expressed in adipose tissue, cardiac muscle, skeletal muscle, liver, and ovary. The SREBP2 mRNA concentration was highest in liver and ovary. Concentrations of FAS and HMG-CoA reductase mRNA were high in liver and lower in other tissues. The apoVLDL-II mRNA was specifically expressed in the liver. The differences between mRNA concentrations of SREBP1, SREBP2, and FAS in the livers of laying and prelay ducks were not significant. However, the concentrations of hepatic HMG-CoA reductase and apoVLDL-II mRNA were higher in the laying ducks than in prelay ducks. Therefore, laying may affect particular aspects of lipid metabolism, especially biochemical pathways that involved apoVLDL-II and HMG-CoA reductase.

Cloning and expression of Tsaiya duck liver fatty acid binding protein

Liver basic fatty acid (FA)-binding protein (Lb-FABP) cDNA was cloned from the livers of laying Tsaiya ducks and used to generate probes for quantification of the Lb-FABP mRNA in Tsaiya ducks. The full-length Lb-FABP cDNA of the Tsaiya duck was highly homologous with that of the mallard (99%), chicken (88%), and iguana (73%). The amino acid sequence was also highly homologous to Lb-FABP found in birds and reptiles, indicating a similar function of the Tsaiya duck Lb-FABP to those species. The calculated molecular weight for the cloned duck Lb-FABP was 14,043g/mol. The Lb-FABP was highly expressed in the liver of laying Tsaiya ducks and not detectable in heart, ovary, intestine, or adipose tissues. The expression of Tsaiya duck Lb-FABP in the skeletal muscle was also detected, and the sequence was confirmed. The greater expression of the hepatic Lb-FABP in the egg-laying Tsaiya ducks than the prelaying ducks paralleled the higher FA use by the laying ducks. These results suggest that hepatic Lb-FABP may be needed for egg production when FA metabolism is high for the ducks. Feeding laying Tsaiya ducks with diets enriched with 2% docosahexaenoic acid (DHA) oil for 2 wk significantly increased hepatic DHA content compared with in ducks fed a 2% butter basal diet. There was no effect of dietary DHA enrichment on the expression of Lb-FABP in the liver of Tsaiya ducks. The results suggest that even though the Lb-FABP may be involved in hepatic FA metabolism, the effect of individual FA on liver Lb-FABP in laying Tsaiya ducks needs to be further studied.

The effect of dietary docosahexaenoic acid on the expression of porcine lipid metabolism-related genes1

To study the effect of dietary docosahexaenoic acid (DHA) on the expression of adipocyte determination and differentiation-dependent factor 1 (ADD1) mRNA in pig tissues, weaned, crossbred pigs (30 d of age) were fed either 2% (as-fed basis) tallow or DHA oil for 18 d. Body weight of the pigs was not affected by different dietary fatty acid (FA) compositions. The plasma and liver FA composition reflected the composition of the diet. The adipose tissue and skeletal muscle FA composition only partially reflected the diet, indicating either a slower FA turnover or that a greater proportion of the FA in these tissues is from endogenous FA synthesis. The ADD1 is an important transcription factor that modulates transcription of FA synthase to regulate the endogenous FA synthesis in the liver and adipose tissue. The ADD1 mRNA was decreased (P < 0.05) in the liver of DHA-treated pigs compared with that of the tallow-treated pigs. The diets did not have an effect on the ADD1 mRNA in pig adipose tissue. The ADD1 transcript was not detected in pig skeletal muscle. These results indicate that significant enrichment of liver DHA content inhibits the expression of ADD1 mRNA. Such an effect is similar to that reported in porcine differentiating adipocytes cultured with DHA. The liver and muscle acyl CoA oxidase mRNA concentration was increased (P < 0.05) by DHA oil treatment, suggesting that DHA treatment may increase peroxisomal fatty acid oxidation in these two tissues. Our present observations demonstrate that dietary DHA enrichment not only affects tissue DHA concentration but also mildly modifies the expression of genes related to fatty acid metabolism in the porcine liver and skeletal muscle.

Effect of polyunsaturated fatty acids on the expression of transcription factor adipocyte determination and differentiation-dependent factor 1 and of lipogenic and fatty acid oxidation enzymes in porcine differentiating adipocytes

Polyunsaturated fatty acids (FA) regulate genes involved in lipid metabolism. The effects of polyunsaturated FA on the transcription factor adipocyte determination and differentiation-dependent factor (ADD) 1 and fatty acid synthase (FAS) mRNA in differentiating porcine adipocytes were measured using a stromal vascular cell culture system. Porcine stromal vascular cells were isolated from subcutaneous adipose tissues and plated in Dulbecco's modified Eagle's medium (DMEM)-nutrient mixture F-12 Ham (F-12) plus fetal bovine serum (100 ml/l) for 24 h. Then cells were differentiated in DMEM-F12 plus insulin, hydrocortisone and transferrin without or with polyunsaturated FA at 6.25, 25.00 or 100.00 microM. The ADD1 mRNA was decreased by 100.00 microM-arachidonic acid, 6.25 to 100.00 microM-docosahexaenoic acid or cis-9,trans-11-conjugated linoleic acid. The polyunsaturated FA reduced the transcription rate of FAS, but not of ADD1. All three polyunsaturated FA accelerated degradation of ADD1 and FAS mRNA to reduce the abundance of ADD1 and FAS mRNA. Results also showed that polyunsaturated FA inhibit the ADD1 expression, not only of mRNA concentration, but also of mature ADD1 protein concentration, suggesting an overall reduction of ADD1 function by polyunsaturated FA. Our present experiments demonstrate that polyunsaturated FA regulate the gene expression of ADD1 and enzymes involved in lipid metabolism in porcine adipocytes.

Dietary fat has minimal effects on fatty acid metabolism transcript concentrations in pigs

Young, crossbred pigs were fed either a low-fat, corn-based diet; a high-fat, tallow-based diet with a considerable saturated fatty acid (FA) content; or a high-fat, fish oil-based diet with a considerable polyunsaturated FA content, for 14 d. There were six pigs per dietary group (approximately 4-wk-old with a body weight of 6.16 kg). The plasma and adipose tissue FA composition reflected the composition of the diet to a large extent, but also reflected de novo FA synthesis coupled with chain elongation and desaturation. The liver and skeletal muscle FA composition reflected the diet and endogenous synthesis, but the indications for preferential incorporation or exclusion of specific FA were greater in these tissues than in plasma or adipose tissue. An important transcription factor for adipocyte differentiation and other aspects of lipid metabolism is adipocyte determination and differentiation-dependent factor 1 (ADD1). Liver ADD1 messenger RNA (mRNA) tended to be decreased (P = 0.06) in the fish oil-fed group, as well as in the combined high-fat-fed groups (tallow + fish oil) compared to the low-fat-fed group (P = 0.06). The muscle acyl-CoA oxidase mRNA tended to be increased in the tallow-fed group and decreased in fish oil-fed groups (P = 0.06). The muscle carnitine palmitoyltransferase mRNA tended to be elevated in both fat-fed groups (P = 0.07). None of the adipose tissue mRNA were changed by the diet (P > 0.20). The observations suggest there are major differences between rodents and pigs in modulation of transcripts associated with lipid metabolism by the dietary FA composition or concentration. Also, in porcine adipose tissue, as well as in liver and skeletal muscle, these transcripts are rather refractory to modification by dietary FA.

Expression of turkey transcription factors and acyl-coenzyme oxidase in different tissues and genetic populations

Several transcription factors are involved in regulating lipid metabolism in various animal tissues. Peroxisome proliferator-activated receptor (PPAR) gamma and PPARalpha regulate lipogenesis and fatty acid oxidation. Gene fragments for PPARgamma, PPARalpha, and acyl-coenzyme A oxidase (ACO) have been cloned in turkeys, and the sequences of these genes were highly homologous to those of chickens, pigs, and humans. Data showed that turkey PPARgamma and PPARalpha were highly homologous (>97%) with that of the chicken, indicating the genetic relationship between those two species was close. The tissue distribution and genetic effect on mRNA concentrations of PPARgamma, PPARalpha, and ACO in two genetic populations of turkeys [randombred control (RBC2) and growth selected (F line)] was determined. The PPARgamma mRNA was highly expressed in adipose tissue in both populations, but there was no difference between the two populations. The PPARalpha mRNA concentration was high in the liver with less expression in adipose tissue and skeletal muscle. The PPARalpha mRNA concentration was similar between the two genetic populations. The ACO mRNA was expressed in adipose tissue, skeletal muscle, and liver with no difference between the genetic populations. The data suggest that both turkey liver and adipose tissue have considerable capability for fatty acid oxidation and synthesis. Long-term selection for increased 16-wk BW in the F line had no effect on the expression of PPARgamma, PPARalpha, and ACO.

The ontogeny of fatty acid-binding protein in turkey (Meleagridis gallopavo) intestine and yolk sac membrane during embryonic and early posthatch development

Experiments were conducted to confirm the existence and ontogeny of fatty acid binding protein (FABP) in the intestine and yolk sac membrane of turkey poults (Meleagridis gallopavo) during embryonic and early posthatch development. Intestinal (I-) FABP was measured using an immunoblot procedure incorporating anti-chick liver (L-)FABP antisera. FABP activity in both tissues was also confirmed with a ligand-binding assay incorporating 14C-oleic acid. I-FABP did not cross-react with chick L-FABP antisera until hatch, embryonic day 28 (ED 28), after which there was a 39% increase in I-FABP concentration through the first 3 d posthatch (PD 3). FABP concentration calculated on a total intestinal basis (ng/intestine), however, increased 10-fold through PD 6. Specific activity [disintegrations per minute (dpm)/ mg cytosolic protein] was greatest at hatch and decreased slightly thereafter, whereas specific activity of FABP in the yolk sac membrane peaked between ED 16 and ED 19 and then declined. Total yolk sac activity (dpm/yolk sac membrane), however, plateaued at ED 22 before declining to low levels by PD 3, coincident with the period of maximal lipid transfer out of the yolk.

The development of an immunoblotting assay for the quantification of liver fatty acid-binding protein during embryonic and early posthatch development of turkeys (Meleagridis gallopavo)

Turkey (Meleagridis gallopavo) liver cytosolic fatty acid binding protein (FABP) was purified and used as a standard for quantification. An immunoblotting procedure was developed to study the ontogeny of liver cytosolic FABP during embryonic and early posthatch development in turkey poults. Liver FABP activity was also determined indirectly through the use of gel filtration chromatography followed by a ligand-binding assay. The specific activity of liver FABP (ng/mg of cytosolic protein) increased with length of incubation, peaking initially at Day 22, declining between Days 22 and 25, and increasing again from hatch (Day 28) to 6 d posthatch. The specific activity of liver FABP increased 12-fold between Day 13 of incubation and 6 d posthatch compared with total activity, which increased from 946 to 1.01 x 10(6) ng/liver during the same period, a 1,067-fold increase. The results from both analytical procedures were similar, suggesting that the immunoblot method could be used to quantify liver FABP concentrations. The observed increases in FABP activity throughout the embryonic period and first days after hatching paralleled increases in liver lipid concentration. Therefore, liver FABP may be associated with hepatocyte fatty acid transport and metabolism during the latter stages of incubation and early posthatch period.

The developmental expression of acyl-coenzyme A:cholesterol acyltransferase in the yolk sac membrane, liver, and intestine of developing embryos and posthatch turkeys

Acyl-coenzyme A:cholesterol acyltransferase (ACAT) catalyzes the formation of cholesterol esters (CE) from free cholesterol and fatty acyl-coenzyme A. This experiment was conducted to study the ontogeny of ACAT activity in the yolk sac membrane, liver, and intestine during embryonic development and early posthatch growth of turkeys. The ACAT activity was measured on tissue samples collected at 3-d intervals from embryonic Day (ED 13) 13 through 6 d posthatch (PD 6). The ACAT activity (pmol/mg microsomal protein per min) in the yolk sac membrane increased form 840 pmol at ED 13 to 2,497 pmol at ED 22, and subsequently declined to a very low level by PD 3. The high level of enzyme activity at ED 22 is concomitant with the large quantity of CE formed within the yolk sac membrane at this developmental age. Liver ACAT activity increased from 60 pmol at ED 13 to 242 to 243 pmol at ED 25 and PD 3, followed by a decline to 130 pmol by PD 6, mirroring the peak in hepatic CE concentration. This suggests that even during incubation, the liver plays a significant role in lipid metabolism. Intestinal ACAT specific activity increased from 14 pmol (ED 16) to 44 pmol (ED 25), and then declined to 23 pmol by hatch (ED 28), with no further decline through PD 6. Total intestinal ACAT activity (pmol per intestine/min) increased, however, from ED 16 through PD 6. This increase in activity suggests that the total capacity for cholesterol esterification increases during the course of incubation and shortly after hatching.

Expression of porcine transcription factors and genes related to fatty acid metabolism in different tissues and genetic populations

Several transcription factors are involved in regulating lipid metabolism in various tissues of animals. Adipocyte determination and differentiation-dependent factor 1 (ADD1), peroxisome proliferator activated receptor alpha (PPAR alpha), and peroxisome proliferator activated receptor gamma (PPAR gamma) regulate both lipogenesis and fatty acid oxidation. We determined the tissue distribution and genetic difference in mRNA concentrations of these transcription factors in two genetic populations of pigs (Newsham XL-sired Newsham Landrace x Large White Duroc and Duroc-sired US Yorkshire x Duroc-Landrace). We also determined the tissue distribution and genetic difference in the mRNA concentration of fatty acid synthase (FAS) and acyl-CoA oxidase (ACO). Our data showed that ADD1 was highly expressed in adipose tissue and liver and that mRNA concentrations of ADD1 were similar between the two genotypes. The PPAR alpha mRNA concentration was high in adipose tissue and was similar between the two genotypes. In both populations, PPAR gamma mRNA was detected only in adipose tissue. There was no difference between the two genotypes in PPAR gamma mRNA concentration. The ACO mRNA was expressed in adipose tissue, skeletal muscle, and liver with no difference between genotypes. The FAS mRNA concentration in adipose tissue was seven times higher than that in the liver. There was no detectable FAS mRNA in skeletal muscle. These data support the concept that pig adipose tissue has considerable capability for fatty acid oxidation and synthesis. The uniqueness of expression patterns for FAS and ADD1 mRNA further indicates that adipose tissue is significantly involved in fatty acid and triacylglycerol synthesis in pigs.

Expression of porcine adipocyte transcripts during differentiation in vitro and in vivo

Transcript concentrations for the transcription factors, CCAAT enhancer binding protein beta and alpha (C/EBPbeta and C/EBPalpha), plus the adipocyte-characteristic proteins, fatty acid synthase (FAS), glucose transporter 4 (Glut 4), hormone-sensitive lipase (HSL), insulin receptor (InsR), lipoprotein lipase (LPL), and leptin were measured during differentiation of porcine stromal-vascular (S/V) cells in vitro. These same transcripts, excluding FAS and InsR, were measured in porcine adipose tissue from birth to 7 weeks of age. In S/V cells, C/EBPbeta and InsR were continuously elevated. At day 0, C/EBPalpha was approximately 20% of the day 9 value. The LPL increased gradually from day 0 to 9, whereas most other transcripts had a lag period of several days. In tissue, C/EBPbeta was substantial at birth and increased gradually. The C/EBPalpha was relatively low at birth and increased at day 17. The LPL and leptin increased continuously. The Glut 4 was low at birth and increased at day 28. The HSL was relatively low at birth, increased at day 10, and plateaued at day 28. Transcripts in porcine S/V cells develop somewhat differently from adipocyte differentiation models established in clonal cells, but the porcine cells represent a model that should be more applicable to pigs.

Effect of feed restriction on adipose tissue transcript concentrations in genetically lean and obese pigs

To determine possible genetic influences on the steady-state concentrations of several key transcription factor transcripts and the transcript concentrations for adipocyte-characteristic proteins, young, genetically obese and lean pigs were given ad libitum access or feed or were restrictively fed at 50% of ad libitum intake for 5 wk. Obese pigs were smaller and fatter than lean pigs, whether intake was ad libitum or restrictive. Plasma protein, albumin, and cholesterol concentrations were greater in obese than in lean pigs. Plasma NEFA, blood urea nitrogen, triacylglycerols, and postprandial glucose and insulin concentrations were less (P < .02) in pigs fed restrictively than in pigs with ad libitum access to feed, regardless of genetic group. The adipose tissue glucose transporter 4, fatty acid synthase, and leptin transcript concentrations were greater (P < .05) in obese than in lean pigs. The CCAAT/enhancer binding proteins beta and alpha, adipocyte fatty acid binding protein, hormone-sensitive lipase, and the beta1-adrenergic receptor transcript concentrations tended (P < . 10) to be greater in adipose tissue from obese than in that from lean pigs. Several other transcripts were numerically greater in obese than in lean pigs. The data collectively suggest that messenger RNA concentration for several adipose tissue proteins is a contributing factor to the excess fat deposition in these obese pigs. Restricted feeding did not change the concentration of any transcript except that for adipocyte fatty acid binding protein, which was reduced. The accretion of fat was markedly reduced in the restrictively fed pigs, but this diminution does not seem to be regulated by modulation of messenger RNA concentration.

Modulation of porcine adipocyte beta-adrenergic receptors by a beta-adrenergic agonist

Mammalian cells have several mechanisms to decrease the response to beta-adrenergic agonists. Agonists are metabolized or taken up by nerve endings. The beta-adrenergic receptors (betaAR) are inactivated by phosphorylation and removed from the cell membrane, and synthesis is decreased or degradation is increased. Knowledge about adipocyte betaAR desensitization is mostly from rodent adipocytes with > or = 90% beta3AR. Porcine adipocyte betaAR have functional and ligand-binding properties that are quite different from those in many other species. Furthermore, the predominant betaAR subtype in the porcine adipocyte is the beta1AR (70 to 80%). Given these species differences, it might be expected that desensitization in porcine adipocytes would not be totally concordant with the rodent-derived model. Isolated porcine adipocytes were incubated without or with a betaAR agonist, isoproterenol. The total betaAR number, measured by ligand-binding in a crude membrane fraction, tended to be lower after 6 h of incubation without isoproterenol. The addition of 10(-5) M isoproterenol during the incubation caused the betaAR number to decrease 43% compared to cells incubated without isoproterenol. The beta1AR and beta2AR transcript concentrations both decreased 45% after 6 h of incubation without isoproterenol. There was no decrease in mRNA when cells were incubated with isoproterenol. The results suggest the betaAR were desensitized by incubation with isoproterenol, perhaps by phosphorylation and removal from the membrane, but this was not accompanied by modulation of the concentration of transcripts for beta1AR or beta2AR.

Modulation of porcine adipocyte beta-adrenergic receptors by hormones and butyrate

The beta-adrenergic receptors (betaAR) on the surface of mammalian cells are desensitized when the cell is stimulated by betaAR agonists to eliminate excessive response by the cell. Investigations with adipocytes, primarily rodent-derived cells, indicate other hormones and substrates also can modulate the individual betaAR subtypes. For example, glucocorticoids decrease the beta1AR and the beta3AR but increase the beta2AR. Insulin decreases the beta3AR. Thyroid hormones increase the beta3AR and butyrate increases beta1AR and beta2AR but dramatically decreases beta3AR. Because porcine adipocytes have unique functional and ligand-binding properties compared to rodent adipocytes and because porcine adipocytes contain predominantly beta1AR, compared to rodent adipocytes with predominantly beta3AR, we expect the regulation of porcine adipocyte betaAR by hormones and substrates to be different from that in rodent adipocytes. Isolated porcine adipocytes were incubated for 6 and 21 h without and with dexamethasone, insulin, triiodothyronine, or butyrate. Cells incubated without hormone or butyrate had a decreased betaAR number at 21 h. The beta1AR and beta2AR transcript concentrations were decreased after 6 h and tended to rebound after 21 h of incubation. Dexamethasone did not change the total betaAR number but tended to increase the beta1AR and beta2AR transcript concentrations. Insulin increased the betaAR number and decreased both transcript concentrations at 21 h. Triiodothyronine and butyrate did not change the receptor number or transcript concentrations. The results indicate that betaAR transcript concentrations do not accurately predict the betaAR protein concentration (estimated by ligand binding). Results also indicate that betaAR in porcine adipocytes are relatively unresponsive to hormones and butyrate compared to rodent-derived adipocytes described in the literature.

Expression of porcine adipocyte transcripts: tissue distribution and differentiation in vitro and in vivo

Transcription factor transcripts implicated in adipocyte differentiation (peroxisome proliferator-activated receptor gamma (PPAR gamma), retinoid x receptor alpha (RXR alpha), adipocyte determination and differentiation-dependent factor 1 (ADD1), and CCAAT/enhancer binding protein alpha (C/EBP alpha)) and adipocyte-characteristic protein transcripts (lipoprotein lipase (LPL) and adipocyte fatty acid binding protein (aP2)) were measured in pig tissues. Transcripts for PPAR gamma, ADD1, and aP2 were localized in porcine subcutaneous and perirenal adipose tissues; transcripts for C/EBP alpha and LPL were detected in other tissues, but the greatest concentrations were in the adipose tissues. In porcine stromal-vascular cells (S/V cells) differentiating in vitro, transcripts for PPAR gamma and aP2 increased gradually, transcripts for ADD1, and LPL increased early and transcripts for C/EBP alpha increased late. In pigs, adipose tissue transcripts for PPAR gamma, ADD1, and LPL were minimal at birth and increased to 28 days postpartum, transcripts for C/EBP alpha were low until 28 days and transcripts for aP2 were at high levels, regardless of age. Although transcript development was somewhat different in vitro and in vivo, the data suggest PPAR gamma (and ADD1 are involved in regulation of transcripts for LPL and that there may be more partially differentiated precursor cells in S/V cells at day 0 than in adipose tissue at birth.

UV inducibility of rat proliferating cell nuclear antigen gene promoter

Proliferating cell nuclear antigen (PCNA), also known as a cofactor of DNA polymerase delta, is required for eukaryotic cell DNA synthesis and nucleotide excision repair. Expression of PCNA gene is growth-regulated and UV inducible. In our previous study, we have observed that the rat PCNA promoter has the serum responsiveness. In this study, we demonstrate its UV inducibility in CHO.K1 cells. The UV induction of the rat PCNA promoter activity was dose-dependent in the cells synchronized at different phases. In addition, the sequences of the promoter responsible for the UV inducibility were delimited to the region between nucleotides -70 and +125, which contains an AP-1 site and a downstream proximal ATF/CRE site. While mutation of the AP-1 site abrogated the UV inducibility, mutation of the ATF/CRE site enhanced the UV inducibility, suggesting that the two sites play different roles in the UV induction of the promoter. In addition, the role of p53 in the UV induction of rat PCNA promoter was investigated. We found that exogenous p53 was unable to mimic the UV irradiation to induce rat PCNA promoter and that the UV induction of the rat PCNA promoter was seen in p53 deficient cells. Therefore, it is unlikely that the UV induction of the rat PCNA promoter is p53 dependent.

Serum responsiveness of the rat PCNA promoter involves the proximal ATF and AP-1 sites

We have previously shown that the rat PCNA (proliferating cell nuclear antigen) gene promoter is responsive to serum stimulation. In this study, the sequence of the promoter responsive to serum stimulation has been localized in the region between nucleotides -70 and +125 relative to the transcription initiation site. This region contains an ATF site (nucleotides -51 to -44) and an AP-1 site (nucleotides -64 to -58). Mutation at either the ATF or the AP-1 site reduced the serum responsiveness of the promoter. In gel mobility shift assays, nuclear extracts from serum stimulated cells, compared to those from quiescent cells, exhibit an increasing binding activity toward a promoter related oligonucleotide (-70 to -42) which includes the ATF site and the AP-1 site. Formation of the DNA:protein complexes requires the simultaneous involvement of ATF and AP-1 sites as either element can abrogate the complexes in the competition experiment. Both the distance and sequence are essential to complex formation. Moreover, ATF-1 but not ATF-2 (or CREB) has been identified as a major component of the complexes in the antibody supershift or interference experiment. The results of this study suggest that ATF-1 in association with other factors is involved in regulating the serum stimulation of the rat PCNA promoter activity via the proximal ATF and AP-1 sites.

Inclusion of coconut oil in diets for turkey breeders and its effects on embryonic yolk and liver fatty acids

Turkey hens were fed either a standard breeder diet (CON, myristic acid, C14.0, 1.1%; palmitic acid, C16:0, 16.8%; oleic acid, C18:1, 23%; linoleic acid, C18:2, 48.7%) or a diet containing 5% coconut oil (COCO) enriched with medium chain fatty acids (MCFA; lauric acid, C12:0, 22.6%; C14:0, 10.8%; C16:0, 12.5%; C18:1, 14.8%; C18:2, 24.6%). After 10 d on the diets, fresh eggs were collected for yolk lipid and fatty acid (FA) determination. An additional 60 to 95 eggs were incubated and the FA profiles of the neutral lipid (NL) and phospholipid (PL) fractions of yolk sac and liver lipids were determined. The NL fraction of the yolk sac from CON eggs contained less C12:0 (0 vs 0.49%) and C14:0 (0.7 vs 4.6%) and more C18:1 (41.3 vs 37.5%). The PL fraction of the yolk sac from both treatments contained < 1% C14:0, and there was less than a 2% difference between treatments in other FA concentrations. The hepatic NL fraction from both treatments contained < 1% C14:0 and only C18:1 showed > 1% differences between treatments (Control = 59.9%; COCO = 56.62%). There were no dietary effects on the FA profile of hepatic PL. The presence of only minimal quantities of MCFA in hepatic NL and PL suggests that absorbed yolk sac MCFA are extensively metabolized during embryonic development.

Changes in fatty acid profiles in different lipid classes during late development of turkey embryos from two genetic lines

Fatty acid (FA) profiles in embryonic yolk sacs (YS) and livers were studied in embryos from a randombred turkey line (RBC2) and a line selected for body weight at 16 wk (F line). There were no differences in FA profiles of fresh yolk lipids. During the course of incubation, oleic acid (C18:1) was higher and linoleic acid (C18:2) was lower in YS triglyceride (TG) and phospholipid (PL) subclasses in F line compared with RBC2 embryos. In both lines, the C18:1 content of YS cholesteryl esters (CE) increased from 58 to 63% during the last 6 d of incubation. From 22 to 28 d of incubation, there was a constant C18:1 concentration in hepatic CE, which was > 60% of total hepatic CE FA. As incubation proceeded, palmitic acid (C16:0) and C18:1 in hepatic TG decreased from 27 to 16% and 37 to 34%, respectively. The stearic acid (C18:0) in TG increased from 12% at Day 22 to 32% of total FA at hatch (Day 28) in RBC2 embryos compared with a lesser increase in the F line (11.8 to 18.6%). In hepatic PL, arachidonic acid (C20:4) decreased, whereas both C16:0 and C18:0 increased from 22 to 28 d of incubation. During this same time period, there was an overall decline in docosahexaenoic acid (C22:6) only in the RBC2. On Days 26 and 28, F line embryos had greater concentrations of C22:6 and C20:4 in hepatic PL than did RBC2. These results suggest that selection for increased BW has changed the proportional incorporation of different FA into embryonic lipids.

Characterization of changes in yolk sac and liver lipids during embryonic and early posthatch development of turkey poults

In two studies, changes in lipids and fatty acids from the yolk sac and liver of turkeys were determined during incubation and early postnatal growth. In Experiment 1, embryos were collected from Day 13 through 6 d posthatch. Embryos weighed 4.25 g at Day 13, 52.8 g at hatch (Day 28), and 104 g at 6 d. Total yolk lipid (grams per yolk sac) decreased from 9.48 g at Day 13 to 2.52 g at hatch (Day 28). Almost half (47%) of the yolk lipid decreased during the last week of incubation. In Experiment 2, embryos were collected daily from Day 22 through 2 d posthatch. Embryonic weight increased from 32.5 g at Day 22 to 55.8 g at hatch (Day 28), 3 g more than in Experiment 1. On Days 22 and 25, total yolk lipid (grams per yolk sac) was slightly less in Experiment 2 than in Experiment 1, but at hatch (Day 28) there were considerable differences (Experiment 1, 2.52 g; Experiment 2, 0.63 g), concomitant with increased hatch weight in Experiment 2. Liver DM percentage and ether extractable lipid increased as incubation proceeded. Oleic acid comprised the largest proportion of total yolk fatty acids and of liver fatty acids. There was a small but significant increase in yolk sac oleic acid (percentage of total fatty acids) between Day 22 (40%) and hatch (Day 28; 45.4%) and a much larger increase in liver oleic acid (46.6% to 56.5%). The absolute amount of all yolk sac fatty acids declined greatly during the second half of incubation through 6 d posthatch.

Serum responsiveness of the rat PCNA promoter

Expression of proliferating cell nuclear antigen (PCNA) gene is growth-regulated. The growth dependence of the rat PCNA gene promoter activity was investigated. Cultured cells were transfected with the promoter containing plasmid and recovered for 48 h in serum-free medium to become quiescent. Cells were then cultured in serum-containing medium and harvested at certain intervals after serum-stimulation, and the promoter-directed chloramphenicol acetyltransferase activities in cell extracts were measured. The promoter used in this study contained sequences between -693 and +125 in relation to the transcription initiation site. The promoter activity was found to be serum-responsive. However, the serum-responsiveness of the promoter became less obvious when the amount of the promoter increased; meanwhile, the promoter became active in the control unstimulated (or quiescent) cells. It was suspected that the dosage effect was due to the titration of the negative regulatory factor in quiescent cells. The titration experiment with a reporterless construct as competitor for regulatory factors showed that the excess of promoter molecules reduced the promoter activity in serum-stimulated cells, while causing a transiently increase of promoter activity in quiescent cells. Based on these results, it is postulated that the serum-responsiveness of the rat PCNA promoter is controlled by both negative and positive regulatory factors. Consistent with this proposition, promoter binding proteins of 105 and 114 kDa were identified only in serum-stimulated and quiescent cells, respectively, in addition to several other promoter binding proteins (ranging from 76 to 110 kDa) which were seen in both serum-stimulated and quiescent cells.

The concentration of different lipid classes during late embryonic development in a randombred turkey population and a subline selected for increased body weight at sixteen weeks of age

Lipid changes in the yolk sac of the embryo were studied in a randombred population of turkeys (RBC2) and a subline of the RBC2 selected for increased BW at 16 wk (F line). Comparisons of yolk sac and embryonic development were made between 22 d of incubation and hatch (28 d). Poults from the F line had heavier yolk sacs from 24 to 28 d and yolk free body weight was also heavier at hatch (61.1 vs 52.8 g). Yolk sac lipid (percentage of DM) declined faster in F line embryos (69 to 39%) compared with the RBC2 line (62 to 48%). In both lines, embryonic liver dry matter and lipids (percentage of DM) were similar. Yolk sac neutral lipids increased from 22 to 28 d (70 to 80% total lipid) in both lines and there was a concomitant decline in phospholipids (30 to 20%). The direction of the changes was similar for embryonic liver lipid. At 26 and 28 d, there were significantly increased neutral lipids (94 vs 88%) and decreased phospholipids (6 vs 12%) in RBC2 compared with F line embryonic livers. The concentration of cholesterol esters (percentage of total lipid) increased in the yolk sac and embryonic liver during the course of incubation. At 26 and 28 d, livers from RBC2 embryos had increased cholesterol ester concentration compared with livers from the F line.(ABSTRACT TRUNCATED AT 250 WORDS)