A combination of octanoate and oleate promotes in vitro differentiation of porcine intramuscular adipocytes

The Effects of Oleic Acid and Palmitic Acid on Porcine Muscle Satellite Cells

We aimed to determine the effects of oleic acid (OA) and palmitic acid (PA), alone or in combination, on proliferation, differentiation, triacylglycerol (TAG) content, and gene expression in porcine muscle satellite cells (PMSCs). Results revealed that OA-alone- and PA + OA-treated PMSCs showed significantly increased viability than those in the control or PA-alone-treated groups. No significant effects on apoptosis were observed in all three treatments, whereas necrosis was significantly lower in OA-alone- and PA + OA-treated groups than in the control and PA-alone-treated groups. Myotube formation significantly increased in OA-alone and PA + OA-treated PMSCs than in the control and PA-alone-treated PMSCs. mRNA expression of the myogenesis-related genes MyoD1 and MyoG and of the adipogenesis-related genes PPARα, C/EBPα, PLIN1, FABP4, and FAS was significantly upregulated in OA-alone- and PA + OA-treated cells compared to control and PA-alone-treated cells, consistent with immunoblotting results for MyoD1 and MyoG. Supplementation of unsaturated fatty acid (OA) with/without saturated fatty acid (PA) significantly stimulated TAG accumulation in treated cells compared to the control and PA-alone-treated PMSCs. These results indicate that OA (alone and with PA) promotes proliferation by inhibiting necrosis and promoting myotube formation and TAG accumulation, likely upregulating myogenesis- and adipogenesis-related gene expression by modulating the effects of PA in PMSCs.

An immortal porcine preadipocyte cell strain for efficient production of cell-cultured fat

Adding adipose cells to cell-cultured meat can provide a distinctive aroma and juicy texture similar to real meat. However, a significant challenge still exists in obtaining seed cells that can be propagated for long periods, maintain their adipogenic potential, and reduce production costs. In this study, we present a cell strain derived from immortalized porcine preadipocytes that can be subculture for over 40 passages without losing differentiation capacity. This cell strain can be differentiated within 3D bioscaffolds to generate cell-cultured fat using fewer chemicals and less serum. Additionally, it can be expanded and differentiated on microcarriers with upscaled culture to reduce costs and labor. Moreover, it can co-differentiate with muscle precursor cells, producing a pattern similar to real meat. Therefore, our cell strain provides an exceptional model for studying and producing cell-cultured fat.

Effects of linseed oil supplementation duration on fatty acid profile and fatty acid metabolism-related genes in the muscles of Chinese crested white ducks

Meat rich in polyunsaturated fatty acids is considered beneficial to health. Supplementing the diet with linseed oil promotes the deposition of polyunsaturated fatty acids (PUFAs) in poultry, a conclusion that has been confirmed multiple times in chicken meat. However, fewer studies have focused on the effects of dietary fatty acids on duck meat. Therefore, this study aims to evaluate the effects of the feeding time of a linseed oil diet on duck meat performance and gene expression, including meat quality performance, plasma biochemical indicators, fatty acid profile, and gene expression. For this study, we selected 168 Chinese crested ducks at 28 days old and divided them into three groups, with 56 birds in each group. The linseed oil content in the different treatment groups was as follows: the control group (0% flaxseed oil), the 14d group (2% linseed oil), and the 28d group (2% linseed oil). Ducks in the two experimental groups were fed a linseed oil diet for 28 and 14 days at 28 and 42 days of age, respectively. The results showed that linseed oil had no negative effect on duck performance (slaughter rate, breast muscle weight, and leg muscle weight) or meat quality performance (pH, meat color, drip loss, and shear force) (P > 0.05). The addition of linseed oil in the diet increased plasma total cholesterol and high-density lipoprotein cholesterol levels (P < 0.05), while decreasing triglyceride content (P < 0.05). Furthermore, the supplementation of linseed oil for four weeks affected the composition of muscle fatty acids. Specifically, levels of α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid were increased (P < 0.05), while eicosatetraenoic acid content was negatively correlated with flaxseed oil intake (P < 0.05). qRT-PCR analysis further revealed that the expression of FATP1, FABP5, and ELOVL5 genes in the breast muscle, as well as FABP3 and FADS2 genes in the thigh muscle, increased after four weeks of linseed oil supplementation (P < 0.05). However, after two weeks of feeding, CPT1A gene expression inhibited fatty acid deposition, suggesting an increase in fatty acid oxidation (P < 0.05). Overall, the four-week feeding time may be a key factor in promoting the deposition of n-3 PUFAs in duck meat. However, the limitation of this study is that it remains unknown whether longer supplementation time will continue to affect the deposition of n-3 PUFAs. Further experiments are needed to explain how prolonged feeding of linseed oil will affect the meat quality traits and fatty acid profile of duck meat.

Perspectives on scaling production of adipose tissue for food applications

With rising global demand for food proteins and significant environmental impact associated with conventional animal agriculture, it is important to develop sustainable alternatives to supplement existing meat production. Since fat is an important contributor to meat flavor, recapitulating this component in meat alternatives such as plant based and cell cultured meats is important. Here, we discuss the topic of cell cultured or tissue engineered fat, growing adipocytes in vitro that could imbue meat alternatives with the complex flavor and aromas of animal meat. We outline potential paths for the large scale production of in vitro cultured fat, including adipogenic precursors during cell proliferation, methods to adipogenically differentiate cells at scale, as well as strategies for converting differentiated adipocytes into 3D cultured fat tissues. We showcase the maturation of knowledge and technology behind cell sourcing and scaled proliferation, while also highlighting that adipogenic differentiation and 3D adipose tissue formation at scale need further research. We also provide some potential solutions for achieving adipose cell differentiation and tissue formation at scale based on contemporary research and the state of the field.

Evaluation of Fat Accumulation and Adipokine Production during the Long-Term Adipogenic Differentiation of Porcine Intramuscular Preadipocytes and Study of the Influence of Immunobiotics

The degree of fat accumulation and adipokine production are two major indicators of obesity that are correlated with increased adipose tissue mass and chronic inflammatory responses. Adipocytes have been considered effector cells for the inflammatory responses due to their capacity to express Toll-like receptors (TLRs). In this study, we evaluated the degree of fat accumulation and adipokine production in porcine intramuscular preadipocyte (PIP) cells maintained for in vitro differentiation over a long period without or with stimulation of either TNF-α or TLR2-, TLR3-, or TLR4-ligands. The cytosolic fat accumulation was measured by liquid chromatography and the expression of adipokines (CCL2, IL-6, IL-8 and IL-10) were quantified by RT-qPCR and ELISA at several time points (0 to 20 days) of PIP cells differentiation. Long-term adipogenic differentiation (LTAD) induced a progressive fat accumulation in the adipocytes over time. Activation of TLR3 and TLR4 resulted in an increased rate of fat accumulation into the adipocytes over the LTAD. The production of CCL2, IL-8 and IL-6 were significantly increased in unstimulated adipocytes during the LTAD, while IL-10 expression remained stable over the studied period. An increasing trend of adiponectin and leptin production was also observed during the LTAD. On the other hand, the stimulation of adipocytes with TLRs agonists or TNF-α resulted in an increasing trend of CCL2, IL-6 and IL-8 production while IL-10 remained stable in all four treatments during the LTAD. We also examined the influences of several immunoregulatory probiotic strains (immunobiotics) on the modulation of the fat accumulation and adipokine production using supernatants of immunobiotic-treated intestinal immune cells and the LTAD of PIP cells. Immunobiotics have shown a strain-specific ability to modulate the fat accumulation and adipokine production, and differentiation of adipocytes. Here, we expanded the utility and potential application of our in vitro PIP cells model by evaluating an LTAD period (20 days) in order to elucidate further insights of chronic inflammatory pathobiology of adipocytes associated with obesity as well as to explore the prospects of immunomodulatory intervention for obesity such as immunobiotics.

Effects of curcumin and yucca extract addition in feed of broilers on microorganism control (anticoccidial and antibacterial), health, performance and meat quality

The aim of this study was to determine whether curcumin and yucca extract addition in broiler feed improves growth, health, and meat quality, and to measure coccidiostatic and antimicrobial activity so as to enable replacement of conventional performance enhancers. We used 240 birds in four treatments: CN, basal feed with antibiotics and coccidiostatic drugs; CU, feed with 100 mg/kg of curcumin; YE, feed with 250 mg/kg of yucca extract; and CU + YE, feed with the combination of 100 mg curcumin/kg and 250 mg yucca extract/kg. A significant reduction in oocysts was observed in birds supplemented with combined additives (CU + YE) at days 37 compared to other treatments and at 42 days in relation to the CU treatment. At 42 days, the total bacterial counts for the CN and CU treatments were lower than the others. Birds fed the additive had lower numbers of leukocytes, lymphocytes, and heterophils than did those in the CN treatment. The highest levels of antioxidants in meat were observed in the treatments with the additives, together with lower levels of lipid peroxidation compared to the CN. The lowest protein oxidation was observed in the CU + YE treatment in relation to the other treatments. Lower total levels of saturated fatty acids (SFA) were observed in the CU treatment than in the CN. There were lower levels of monounsaturated fatty acids (MUFA) in the meat of birds in the YE treatment in relation to the others. Higher levels of total polyunsaturated fatty acids (PUFA) were observed in birds that consumed curcumin, individually and in combination with yucca extract. Taken together, the data suggest that curcumin and yucca extract are additives that can potentially replace conventional growth promoters; they improved bird health. Changes in the fatty acid profile of meat (increase in the percentage of omegas) are beneficial to the health of the consumer.

Transcriptome Modifications in the Porcine Intramuscular Adipocytes during Differentiation and Exogenous Stimulation with TNF-α and Serotonin

Adipocytes are dynamic cells that have critical functions to maintain body energy homeostasis. Adipocyte physiology is affected by the adipogenic differentiation, cell program, as well as by the exogenous stimulation of biochemical factors, such as serotonin and TNF-α. In this work, we investigated the global transcriptome modifications when porcine intramuscular preadipocyte (PIP) was differentiated into porcine mature adipocyte (pMA). Moreover, we studied transcriptome changes in pMA after stimulation with serotonin or TNF-α by using a microarray approach. Transcriptome analysis revealed that the expression of 270, 261, and 249 genes were modified after differentiation, or after serotonin and TNF-α stimulation, respectively. Expression changes in APP, HNF4A, ESR1, EGR1, SRC, HNF1A, FN1, ALB, STAT3, CBL, CEBPB, AR, FOS, CFTR, PAN2, PTPN6, VDR, PPARG, STAT5A and NCOA3 genes which are enriched in the ‘PPAR signaling’ and ‘insulin resistance’ pathways were found in adipocytes during the differentiation process. Dose-dependent serotonin stimulation resulted in a decreased fat accumulation in pMAs. Serotonin-induced differentially expressed genes in pMAs were found to be involved in the significant enrichment of ′GPCR ligand-binding′, ‘cell chemotaxis’, ‘blood coagulation and complement’, ‘metabolism of lipid and lipoproteins’, ‘regulation of lipid metabolism by PPARA’, and ‘lipid digestion, mobilization and transport’ pathways. TNF-α stimulation also resulted in transcriptome modifications linked with proinflammatory responses in the pMA of intramuscular origin. Our results provide a landscape of transcriptome modifications and their linked-biological pathways in response to adipogenesis, and exogenous stimulation of serotonin- and TNF-α to the pMA of intramuscular origin.

Lipidomic profiling of dairy cattle oocytes by high performance liquid chromatography-high resolution tandem mass spectrometry for developmental competence markers

A comparative lipidomic profiling analysis of dairy cattle oocytes with different developmental competences was performed using a combination of high performance liquid chromatography-high resolution tandem mass spectrometry and multivariate statistical analysis. Significant lipidomic changes were identified in degenerating oocytes. Total triacylglycerol in the degenerating oocytes was 1.8-fold higher than that in the normal oocytes; however, total cardiolipin was 53.5% lesser than that in the normal oocytes, which indicated attenuation of energy metabolism. Compared to those in the normal oocytes, triacylglycerols in the degenerating oocytes were composed of longer and more unsaturated acyl chains. In contrast, the acyl chains in free fatty acids present in the degenerating oocytes were shorter and with lesser degree of unsaturation compared to those in the normal oocytes. Moreover, a significant decrease in degenerating oocytes were found in total phosphatidylinositol (14.8 ± 7.6 pmol vs. 24.8 ± 5.5 pmol), total phosphatidylcholine (20.8 ± 8.7 pmol vs. 33.5 ± 7.2 pmol), and total plasmalogen ethanolamine (9.0 ± 4.7 pmol vs. 16.8 ± 5.2 pmol), which indicated dysfunction of lipid-metabolizing enzymes in oocytes during degeneration. Thus, increase of triacylglycerols together with the decrease of certain phospholipid species could be potential markers of oocyte developmental competence. In addition to providing a new approach to investigate the lipidomic changes in oocyte development, the lipidomic profiling in the present study has revealed insights that hold potential to unravel the role of lipid metabolism in oocyte developmental competence in cattle.

Transcriptome Modifications in Porcine Adipocytes via Toll-Like Receptors Activation

Adipocytes are the most important cell type in adipose tissue playing key roles in immunometabolism. We previously reported that nine members of the Toll-like receptor (TLR) family are expressed in an originally established porcine intramuscular pre-adipocyte (PPI) cell line. However, the ability of TLR ligands to modulate immunometabolic transcriptome modifications in porcine adipocytes has not been elucidated. Herein, we characterized the global transcriptome modifications in porcine intramuscular mature adipocytes (pMA), differentiated from PPI, following stimulation with Pam3csk4, Poly(I:C) or LPS which are ligands for TLR2, TLR3, and TLR4, respectively. Analysis of microarray data identified 530 (218 up, 312 down), 520 (245 up, 275 down), and 525 (239 up, 286 down) differentially expressed genes (DEGs) in pMA following the stimulation with Pam3csk4, Poly(I:C), and LPS, respectively. Gene ontology classification revealed that DEGs are involved in several biological processes including those belonging to immune response and lipid metabolism pathways. Functionally annotated genes were organized into two groups for downstream analysis: immune response related genes (cytokines, chemokines, complement factors, adhesion molecules, and signal transduction), and genes involved with metabolic and endocrine functions (hormones and receptors, growth factors, and lipid biosynthesis). Differential expression analysis revealed that EGR1, NOTCH1, NOS2, TNFAIP3, TRAF3IP1, INSR, CXCR4, PPARA, MAPK10, and C3 are the top 10 commonly altered genes of TLRs induced transcriptional modification of pMA. However, the protein-protein interaction network of DEGs identified EPOR, C3, STAR, CCL2, and SAA2 as the major hub genes, which were also exhibited higher centrality estimates in the Gene-Transcription factor interaction network. Our results provide new insights of transcriptome modifications associated with TLRs activation in porcine adipocytes and identified key regulatory genes that could be used as biomarkers for the evaluation of treatments having immunomodularoty and/or metabolic functional beneficial effects in porcine adipocytes.

Research Advancements in Porcine Derived Mesenchymal Stem Cells

In the present era of stem cell biology, various animals such as Mouse, Bovine, Rabbit and Porcine have been tested for the efficiency of their mesenchymal stem cells (MSCs) before their actual use for stem cell based application in humans. Among them pigs have many similarities to humans in the form of organ size, physiology and their functioning, therefore they have been considered as a valuable model system for in vitro studies and preclinical assessments. Easy assessability, few ethical issues, successful MSC isolation from different origins like bone marrow, skin, umbilical cord blood, Wharton’s jelly, endometrium, amniotic fluid and peripheral blood make porcine a good model for stem cell therapy. Porcine derived MSCs (pMSCs) have shown greater in vitro differentiation and transdifferention potential towards mesenchymal lineages and specialized lineages such as cardiomyocytes, neurons, hepatocytes and pancreatic beta cells. Immunomodulatory and low immunogenic profiles as shown by autologous and heterologous MSCs proves them safe and appropriate models for xenotransplantation purposes. Furthermore, tissue engineered stem cell constructs can be of immense importance in relation to various osteochondral defects which are difficult to treat otherwise. Using pMSCs successful treatment of various disorders like Parkinson’s disease, cardiac ischemia, hepatic failure, has been reported by many studies. Here, in this review we highlight current research findings in the area of porcine mesenchymal stem cells dealing with their isolation methods, differentiation ability, transplantation applications and their therapeutic potential towards various diseases.

Nutrigenomics and Beef Quality: A Review about Lipogenesis

The objective of the present review is to discuss the results of published studies that show how nutrition affects the expression of genes involved in lipid metabolism and how diet manipulation might change marbling and composition of fat in beef. Several key points in the synthesis of fat in cattle take place at the molecular level, and the association of nutritional factors with the modulation of this metabolism is one of the recent targets of nutrigenomic research. Within this context, special attention has been paid to the study of nuclear receptors associated with fatty acid metabolism. Among the transcription factors involved in lipid metabolism, the peroxisome proliferator-activated receptors (PPARs) and sterol regulatory element-binding proteins (SREBPs) stand out. The mRNA synthesis of these transcription factors is regulated by nutrients, and their metabolic action might be potentiated by diet components and change lipogenesis in muscle. Among the options for dietary manipulation with the objective to modulate lipogenesis, the use of different sources of polyunsaturated fatty acids, starch concentrations, forage ratios and vitamins stand out. Therefore, special care must be exercised in feedlot feed management, mainly when the goal is to produce high marbling beef.

Comparison of fatty acid profile in the chicken meat after feeding with narasin, nicarbazin and salinomycin sodium and phyto-additive substances

The purpose of this study was an experimental investigation and a statistical evaluation of the influence of various additives in feed mixtures of broiler chickens on fatty acids content and their ratio in breast and thigh muscles. First feed additive consisted of narasin, nicarbasin and salinomycin sodium, and other five additives were of phytogenic origin. In vivo experiment was realized on the poultry experimental station with deep litter breeding system. A total of 300 one-day-old hybrid chickens Cobb 500 divided into six groups were used for the experiment. The experimental period was divided into four phases, i.e. Starter, Grower 1, Grower 2 and Final, according to the application of commercial feed mixture of soy cereal type. Additive substances used in feed mixtures were different for each group. Basic feed mixtures were equal for all groups. Fatty acid profile of breast and thigh muscles was measured by the method of FT IR Nicolet 6700. Investigated additive substances in the feed mixtures did not have statistically significant effect on fatty acid content and omega-6/omega-3 polyunsaturated fatty acid (PUFA) ratio in breast and thigh muscles. Strong statistically significant relation between omega-6 PUFAs and total PUFAs were proved by experiment. A relation between omega-3 PUFAs and total PUFAs was found only in the group with Biocitro additive.

Advanced application of porcine intramuscular adipocytes for evaluating anti-adipogenic and anti-inflammatory activities of immunobiotics

We previously established a clonal porcine intramuscular preadipocyte (PIP) line and we were able to establish a protocol to obtain functional mature adipocytes from PIP cells. We hypothesized that both PIP cells and mature adipocytes are likely to be useful in vitro tools for increasing our understanding of immunobiology of adipose tissue, and for the selection and study of immunoregulatory probiotics (immunobiotics) able to modulate adipocytes immune responses. In this study, we investigated the immunobiology of PIP cells and mature adipocytes in relation to their response to TNF-α stimulation. In addition, we evaluated the possibility that immunobiotic microorganisms modify adipogenesis and immune functions of porcine adipose tissue through Peyer’s patches (PPs) immune-competent cells. We treated the porcine PPs immune cells with different probiotic strains; and we evaluated the effect of conditioned media from probiotic-stimulated immune cells in PIP cells and mature adipocytes. The Lactobacillus GG and L. gasseri TMC0356 showed remarkable effects, and were able to significantly reduce the expression of pro-inflammatory factors and negative regulators (A20, Bcl-3, and MKP-1) in adipocytes challenged with TNF-α. The results of this study demonstrated that the evaluation of IL-6, and MCP-1 production, and A20 and Bcl-3 down-regulation in TNF-α-challenged adipocytes could function as biomarkers to screen and select potential immunobiotic strains. Taking into consideration that several in vivo and in vitro studies clearly demonstrated the beneficial effects of Lactobacillus GG and L. gasseri TMC0356 in adipose inflammation, the results presented in this work indicate that the PIP cells and porcine adipocytes could be used for the screening and the selection of new immunobiotic strains with the potential to functionally modulate adipose inflammation when orally administered.

Stimulatory effect of plasma samples from fattening cattle on adipogenesis-related gene expression in preadipocyte cells

It is desirable to produce beef with high levels of monounsaturated fatty acids (MUFA), as this is related to fat softness and palatability. However, the physiology of MUFA synthesis in bovine fat during the fattening process remains to be established. In this study, in order to elucidate the relationship between plasma components and the fatty acid composition of intramuscular fat, we investigated the effect of plasma obtained from fattening cattle on the messenger RNA (mRNA) expressions of the adipogenesis-related gene in a clonal bovine intramuscular preadipocyte line (BIP cells). The mRNA expressions of stearoyl-CoA desaturase, adipocyte Protein 2, peroxisome proliferator-activated receptor gamma and sterol regulatory element-binding protein 1 in BIP cells were significantly higher following treatment with those plasma samples collected from the cattle with the highest diaphragmatic unsaturated fatty acids to saturated fatty acids ratio (US/S). Furthermore, the concentration of nonesterified fatty acid (NEFA) in the plasma samples had an inverse correlation with carcass diaphragmatic US/S. These results indicate that cattle with a low ratio of US/S in fat may be discriminated from the population of fattening cattle before slaughter by measuring the effect of their plasma on gene expression in BIP cells as well as their plasma concentration and composition of NEFA.

Phloretin promotes adipocyte differentiation in vitro and improves glucose homeostasis in vivo

Adipocyte dysfunction is associated with many metabolic diseases such as obesity, insulin resistance and diabetes. Previous studies found that phloretin promotes 3T3-L1 cells differentiation, but the underlying mechanisms for phloretin's effects on adipogenesis remain unclear. In this study, we demonstrated that phloretin enhanced the lipid accumulation in porcine primary adipocytes in a time-dependent manner. Furthermore, phloretin increased the utilization of glucose and nonesterified fatty acid, while it decreased the lactate output. Microarray analysis revealed that genes associated with peroxisome proliferator-activated receptor-γ (PPARγ), mitogen-activated protein kinase and insulin signaling pathways were altered in response to phloretin. We further confirmed that phloretin enhanced expression of PPARγ, CAAT enhancer binding protein-α (C/EBPα) and adipose-related genes, such as fatty acids translocase and fatty acid synthase. In addition, phloretin activated the Akt (Thr308) and extracellular signal-regulated kinase, and therefore, inactivated Akt targets protein. Wortmannin effectively blocked the effect of phloretin on Akt activity and the protein levels of PPARγ, C/EBPα and fatty acid binding protein-4 (FABP4/aP2). Oral administration of 5 or 10 mg/kg phloretin to C57BL BKS-DB mice significantly decreased the serum glucose level and improved glucose tolerance. In conclusion, phloretin promotes the adipogenesis of porcine primary preadipocytes through Akt-associated signaling pathway. These findings suggested that phloretin might be able to increase insulin sensitivity and alleviate the metabolic diseases.

Comparison of the adipogenesis in intramuscular and subcutaneous adipocytes from Bamei and Landrace pigs

Fat deposition is a complex process involving proliferation, differentiation, and lipogenesis of adipocytes. Bamei and Landrace are considered to represent fat- and lean-type pig breeds. Subcutaneous (SC) and intramuscular (IM) pre-adipocytes were cultured to compare the proliferation and lipogenesis in these breeds. The differentiated adipocytes were exposed to glucose or insulin to evaluate their effects on lipogenesis and lipogenic gene expression. Pre-adipocytes proliferated dramatically faster in SC vs. IM cells, and in Bamei vs. Landrace breeds. Lipogenesis and lipogenic gene expression had a greater increase in Bamei than in Landrace, and in SC vs. IM in the process of differentiation. Glucose markedly promoted lipogenesis and lipogenic gene expression in differentiated adipocytes. The stimulation of high-glucose levels on lipogenesis and ChREBP and lipogenic gene expression was higher in SC than IM adipocytes, and in Bamei vs. Landrace. Insulin largely increased SREBP-1c expression, however it modestly stimulated lipogenesis and lipogenic gene expression, and there was no difference between cell populationsor between breeds. These data demonstrated that regional and varietal differences obviously existed in the development of porcine adipocytes. The proliferation and differentiation capacity of pre-adipocytes, and the adipocyte lipogenesis stimulated by glucose, are stronger in Bamei than Landrace, and in SC vs. IM adipocytes independent of breed.

Comparison of meat quality characteristics and oxidative stability between conventional and free-range chickens

The aim of this research was to evaluate quality traits and oxidative stability of meat products from free-range (FR) and conventionally (C) raised chickens as they actually reach consumers in the Italian retail market. Free-range female and male chickens (n = 1,500 + 1,500), medium growing ISA strain, were raised under commercial conditions for 56 (1.8 kg of live weight) and 70 d (3.1 kg of live weight), respectively; C female and male birds (n = 5,000 + 5,000) were a fast growing hybrid (Ross 708) and were separately raised for 39 (1.9 kg of live weight) and 50 d (3.1 kg of live weight), respectively. A total of 96 chickens (equally divided by production system and sex) were slaughtered in 2 separate sessions to obtain the main 2 commercial categories (rotisserie and cut-up, respectively). After slaughtering, 12 carcasses of each treatment group were randomly selected and used to assess quality properties, chemical composition, and oxidation stability of breast and leg meat. The C birds had dramatic higher carcass and breast meat yield, whereas FR had higher wing and leg yields. The FR birds exhibited higher water holding capacity in both breast and leg meat. Although shear force did not differ in breast meat, legs from FR birds were tougher. Fatty acid composition of FR breast and thigh meat of both categories were characterized by a higher polyunsaturated fatty acid n-6-/n-3 ratio. In general, a low lipid oxidation level (peroxide value < 1.3 mEq O2/kg of lipid and TBA reactive substances < 0.2 mg malondialdehyde/kg of sample) was found in breast and legs, regardless of the commercial category. However, the C system significantly increased peroxide value in rotisserie thigh meat, whereas FR led to a significantly higher TBA reactive substances in breast meat. Our results demonstrated that free range can modify the properties of chicken meat and also highlighted the importance of the bird genetic background to select nutritional strategies to improve meat quality traits and oxidative stability in poultry.

Changes in gene expression in a porcine preadipocyte cell line during differentiation

Adipocyte differentiation plays an important role in the formation of fat tissues in pigs and affects meat quality and productivity. Clarification of the nature of the pig genes that participate in adipocyte differentiation will provide a clue to the regulation of fat content and thickness in pig carcases by dietary control; it will also help to find target genes for exploring potentially useful polymorphisms for molecular breeding aimed at fat traits. We constructed a DNA oligomer microarray based on pig transcripts, and we used the array to investigate time-dependent changes in gene expression in the PSPA porcine preadipocyte cell line during differentiation into adipocytes. We selected genes with markedly altered expression (at least fivefold difference in comparison with expression in undifferentiated cells) and classified them into five groups according to gene expression pattern. In the early stage after stimulation of adipocyte differentiation, we observed up-regulation of many genes encoding proteins involved in regulating cell proliferation and transcription. Among the probes corresponding to transcripts that showed marked changes in expression, 27 were located within previously reported QTL regions for traits related to adipose tissues. These results will be valuable resources for finding the genes responsible for fat-related traits that have been identified in previous studies using various pig resource families.

Promotion of intramuscular fat accumulation in porcine muscle by nutritional regulation

Recently, pork with marbling has received attention as good quality pork and scientists are required to develop methods to produce pork with reasonable amounts of intramuscular fat (IMF). The aim of this review is to describe studies relevant to promotion of IMF accumulation in porcine muscle by nutritional regulation. The main focus is on effect of dietary lysine levels. First, we found dietary low lysine up-regulated glucose transporter protein 4 messenger (m)RNA expression in Longissimus dorsi (L. dorsi) and Rhomboideus muscles. In addition, the proportion of oxidative fiber of both muscles was also enhanced by dietary low lysine. Because it has been observed that higher oxidative capacity is associated with higher IMF content, we hypothesized that dietary low lysine would promote IMF accumulation. Further, higher mRNA abundance of peroxisome proliferator-activated receptor γ, a master regulator of adipogenesis, in both muscles induced by dietary low lysine, supported this hypothesis. Indeed, IMF content of L. dorsi muscle of finishing pigs given a low lysine diet for 2 months until reaching the market weight was twice that of pigs given a control diet. Possible underlying mechanisms of IMF accumulation in porcine muscle and future perspectives are also discussed in this review.

Effects of lysophosphatidic acid on the in vitro proliferation and differentiation of a novel porcine preadipocyte cell line

We examined the effects of lysophosphatidic acid (LPA) on in vitro proliferation and differentiation of a porcine preadipocyte cell line, DFAT-P, and a mouse preadipocyte cell line, 3T3-L1. During the proliferation and differentiation phases, DFAT-P and 3T3-L1 cells expressed only the endothelial differentiation gene (EDG)-2 receptor and not EDG-4 and EDG-7 receptors. LPA promoted the proliferation of DFAT-P cells more extensively than that of 3T3-L1 cells. After adipogenic induction, LPA inhibited glycerol-3-phosphate dehydrogenase activity and lipid droplet accumulation, and suppressed peroxisome proliferator-activated receptor γ (PPARγ) protein expression, this inhibitory effect in DFAT-P cells was twice as high as that in 3T3-L1 cells. Furthermore, treatments with low LPA concentrations significantly inhibited adipocyte differentiation in DFAT-P cells but not in 3T3-L1 cells. We conclude that LPA promotes the proliferation of porcine preadipocytes through the EDG-2 receptor but inhibits their differentiation, and these effects depend on the down-regulation of PPARγ expression via the EDG-2 receptor. Furthermore, DFAT-P cells are more sensitive to LPA than 3T3-L1 cells. These findings in a porcine model will contribute to the understanding of LPA action mechanisms on in vitro proliferation and differentiation of preadipocytes in domestic animals and/or humans.

Global comparison of gene expression profiles between intramuscular and subcutaneous adipocytes of neonatal landrace pig using microarray

The objective of this study was to compare the differences of gene expression profiles between intramuscular and subcutaneous adipocytes originated from the isolated preadipocytes in vitro. Cytosolic triglyceride determination indicated that subcutaneous adipocytes accumulated more lipid than intramuscular adipocytes did at the late stage of differentiation. Microarray assay revealed that 172 probes representing 133 genes were differentially expressed, among which 46 genes were highly expressed in intramuscular adipocytes and the other 87 genes were highly expressed in subcutaneous adipocytes. Real-time PCR confirmed that genes related to lipid metabolism, such as LPL, FABP4, FABP5 and OSBPL10, were predominantly expressed in subcutaneous adipocytes, whereas BMP4 and BMP7 were highly expressed in intramuscular adipocytes. The results indicated that the accumulation of lipid mass in subcutaneous adipocytes might be due to the highly expressed genes related to lipid metabolism, and the high levels of BMP4 and BMP7 in intramuscular adipocytes suggested that BMPs might be involved in the differentiation of intramuscular adipocytes.

Establishment and characteristics of porcine preadipocyte cell lines derived from mature adipocytes

Development of established preadipocyte cell lines, such as 3T3-L1 and 3T3-F442A, greatly facilitated the study of molecular mechanisms of adipocyte differentiation under defined conditions. Most of these cell lines are derived from mouse embryos, and preadipocyte cell lines of other species have not yet been maintained in culture long enough to study differentiation under a variety of conditions. This is the first report on the establishment of porcine preadipocyte cell lines derived from mature adipocytes by a simple method, known as ceiling culture, for culturing mature adipocytes in vitro. This cell line can proliferate extensively until the cells become confluent and fully differentiated into mature adipocytes, depending on adipogenic induction. No changes in their differentiation pattern are observed during their propagation, and they have been successfully carried and differentiated for at least 37 passages. This cell line maintains a normal phenotype without transforming spontaneously, even after long-term maintenance in culture. This achievement may lead to easy establishment of porcine preadipocyte cell lines and novel model systems for studying the mechanisms of adipocyte differentiation and metabolism as a substitute for human preadipocytes.

Cellular regulation of bovine intramuscular adipose tissue development and composition

It is well documented that grain feeding stimulates adipogenesis in beef cattle, whereas pasture feeding depresses the development of adipose tissues, including intramuscular (i.m.) adipose tissue. Additionally, production practices that depress adipocyte differentiation also limit the synthesis of MUFA. Marbling scores and MUFA increase in parallel suggesting that stearoyl-coenzyme A desaturase (SCD) gene expression is closely associated with and necessary for marbling adipocyte differentiation. Similarly, marbling scores and fatty acid indices of SCD activity are depressed in response to dietary vitamin A restriction. In bovine preadipocytes, vitamins A and D both decrease glycerol-3-phosphate dehydrogenase (GPDH) activity, an index of adipocyte differentiation, whereas incubation of bovine preadipocytes with l-ascorbic acid-2-phosphate increases GPDH activity. Exposing bovine preadipocytes to zinc also stimulates adipogenesis, putatively by inhibiting nitric oxide (NO) production. However, incubation of bovine preadipocytes with arginine, a biological precursor of NO, strongly promotes differentiation in concert with increased SCD expression. This suggests that the effect of either arginine or zinc on adipogenesis is independent of NO synthesis in bovine preadipocytes. Enhanced expression of SCD is associated with a greater accumulation of MUFA both in bovine preadipocyte cultures and during development in growing steers. In bovine preadipocytes, trans-10, cis-12 CLA strongly depresses adipocyte differentiation and SCD gene expression, thereby reducing MUFA concentrations. The bovine preadipocyte culture studies suggest that any production practice that elevates vitamins A or D or trans-10, cis-12 CLA in bovine adipose tissue will reduce i.m. adipose tissue development. Conversely, supplementation with vitamin C or zinc may promote the development of i.m. adipose tissue.