Adipogenesis, the complex development from preadipocytes or mesenchymal stem cells to mature adipocytes, is essential for fat formation and metabolism of adipose tissues in mammals. It has been reported to be regulated by hormones and various adipogenic transcription factors which are expressed as a transcriptional cascade promoting adipocyte differentiation, leading to the mature adipocyte phenotype. Recent findings indicate that microRNAs (miRNAs), a family of small RNA molecules of approximately 22 nucleotides in length, are involved in the regulatory network of many biological processes, including cell differentiation, through post-transcriptional regulation of transcription factors and/or other genes. In this review, we focus on the recent understanding of the roles of miRNAs in adipogenesis, including the most recent and relevant findings that support the role of several miRNAs as pro- or antiadipogenic factors regulating adipogenesis in mice, human and cattle to propose the future role of miRNA in adipogenesis of farm animal models.

BackgroundMicroRNAs (miRNAs) are a class of molecular regulators found to participate in numerous biological processes, including adipogenesis in mammals. This study aimed to evaluate the differences of miRNA expression between bovine subcutaneous (backfat) and visceral fat depots (perirenal fat) and the dietary effect on miRNA expression in these fat tissues.Methodology/Principal FindingsFat tissues were collected from 16 Hereford×Aberdeen Angus cross bred steers (15.5 month old) fed a high-fat diet (5.85% fat, n = 8) or control diet (1.95% fat, n = 8). Total RNA from each animal was subjected to miRNA microarray analysis using a customized Agilent miRNA microarray containing 672 bovine miRNA probes. Expression of miRNAs was not equal between fat depots as well as diets: 207 miRNAs were detected in both fat depots, while 37 of these were found to be tissue specific; and 169 miRNAs were commonly expressed under two diets while 75 were diet specific. The number of miRNAs detected per animal fed the high fat diet was higher than those fed control diet (p = 0.037 in subcutaneous fat and p = 0.002 visceral fat). Further qRT-PCR analysis confirmed that the expression of some miRNAs was highly influenced by diet (miR-19a, -92a, -92b, -101, -103, -106, -142–5p, and 296) or fat depot (miR-196a and -2454).Conclusions/SignificanceOur results revealed that the miRNA may differ among adipose depots and level of fat in the diet, suggesting that miRNAs may play a role in the regulation of bovine adipogenesis.

BackgroundMicroRNAs (miRNAs) are small non-coding RNAs found to regulate several biological processes including adipogenesis. Understanding adipose tissue regulation is critical for beef cattle as fat is an important determinant of beef quality and nutrient value. This study analyzed the association between genomic context characteristics of miRNAs with their expression and function in bovine adipose tissue. Twenty-four subcutaneous adipose tissue biopsies were obtained from eight British-continental crossbred steers at 3 different time points. Total RNA was extracted and miRNAs were profiled using a miRNA microarray with expression further validated by qRT-PCR.ResultsA total of 224 miRNAs were detected of which 155 were expressed in all steers (n = 8), and defined as the core miRNAs of bovine subcutaneous adipose tissue. Core adipose miRNAs varied in terms of genomic location (59.5% intergenic, 38.7% intronic, 1.2% exonic, and 0.6% mirtron), organization (55.5% non-clustered and 44.5% clustered), and conservation (49% highly conserved, 14% conserved and 37% poorly conserved). Clustered miRNAs and highly conserved miRNAs were more highly expressed (p < 0.05) and had more predicted targets than non-clustered or less conserved miRNAs (p < 0.001). A total of 34 miRNAs were coordinately expressed, being part of six identified relevant networks. Two intronic miRNAs (miR-33a and miR-1281) were confirmed to have coordinated expression with their host genes, transcriptional factor SREBF2 and EP300 (a transcriptional co-activator of transcriptional factor C/EBPα), respectively which are involved in lipid metabolism, suggesting these miRNAs may also play a role in regulation of bovine lipid metabolism/adipogenesis. Furthermore, a total of 17 bovine specific miRNAs were predicted to be involved in the regulation of energy balance in adipose tissue.ConclusionsThese findings improve our understanding on the behavior of miRNAs in the regulation of bovine adipogenesis and fat metabolism as it reveals that miRNA expression patterns and functions are associated with miRNA genomic location, organization and conservation.

Fat deposition influences both meat quality and animal productivity. However, it is not clear how fat development is regulated in growing and fattening beef cattle. This study characterized proteomic changes in subcutaneous adipose tissue from steers fed a high-grain diet in an effort to understand the molecular mechanisms of fat development during feedlot production. Eight British-Continental crossbred steers had two subcutaneous adipose tissue biopsies at 12 and 15 mo of age. Protein expression in fat samples was profiled using liquid chromatography-tandem mass spectrometry (LC-MS/MS). During the finishing period, steers increased subcutaneous adipose tissue mass with concomitant changes in the proteome profile, but the nature of these changes varied among steers. The expression of 123 out of 627 identified proteins differed (P <: 0.05) between 2 ages. Functional analyses on differentially expressed proteins revealed that 20.2% of them were associated with cellular growth and proliferation of adipose tissue. There were 17 out of 108 differentially expressed proteins associated with lipid metabolism, which were acyl-CoA synthetase medium-chain family member 1 (ACSM1), annexin A1 (ANXA1), apolipoprotein C-III (APOC3), apolipoprotein H (beta-2-glycoprotein I; APOH), EH-domain containing 1 (EHD1), coagulation factor II (thrombin; F2), gelsolin (GSN), lamin A/C (LMNA), mitogen-activated protein kinase kinase 1 (MAP2K1), myosin, heavy chain 9, non-muscle (MYH9), orosomucoid 1 (ORM1), protein disulfide isomerase family A, member 3 (PDIA3), retinol binding protein 4, plasma (RBP4), renin binding protein (RENBP), succinate dehydrogenase complex, subunit A, flavoprotein (Fp; SDHA), serpin peptidase inhibitor, clade C (antithrombin), member 1 (SERPINC1), and serpin peptidase inhibitor, clade G (C1 inhibitor), member 1 (SERPING1). Further analysis of the expression levels of proteins associated with lipid metabolism indicated a downregulation in the synthesis of fatty acids at the cellular level at 15 compared to 12 mo of age. These results suggest that even though adipose tissue expanded, fat anabolism was reduced in adipocytes during growth, revealing a coordinated balance between subcutaneous fat mass and the cellular abundance of lipogenic proteins to control the rate of fat deposition in growing beef cattle. The findings observed in this study expand our understanding on how proteome of bovine adipose tissue is regulated during growth, which might help the development in the future of new strategies to manipulate adiposity in beef cattle in a manner that improves meat quality and animal productivity.

The quail raising in Brazil has increased through the last years and the incubation procedures are important to maintenance and improvement of quail egg production. To obtain a sufficient number of eggs to fill an incubator, eggs are usually accumulated in storage over a period from 1 day up to 3 weeks before incubation. The objective of this research was to verify the effect of egg storage on hatchability and egg weight loss for two lineages of Japanese quails. Sixty four Japanese quails were divided in two groups: G1 (n=32) for meat production and G2 (n=32) for egg production. They were used for serial egg collections that were performed every day, during 15 consecutively days, totaling 600 eggs. After collection they were placed in refrigerated room (20°C and 60% of relative humidity) and submitted to different periods of storage, from 0 day until 14 days, according to their collection day. The incubation occurred at 37.6°C and 60% RH. The weight measurements were done during storage, incubation and hatching. The results showed that for Meat type and Egg type quails, the egg hatchability was around 84% until 10 days of storage, and then this rate decreased significantly. Both types of quail eggs presented similar weight loss during storage and incubation. The research showed that quail eggs present great hatchability until 10 days of storage and that eggs submitted to storage present a reduced weight loss during incubation

Knowledge of the molecular mechanisms that regulate ovine adipogenesis is very limited. MicroRNAs (miRNA) have been reported as one of the regulatory mechanisms of adipogenesis. This study aimed to compare the expression of miRNA related to ovine adipogenesis in different adipose depots and to investigate whether their expression is affected by dietary fatty acid composition. We also investigated the role of miRNA in adipogenic gene regulation. Subcutaneous and visceral adipose tissue samples were collected at slaughter from 12 Canadian Arcott lambs fed a barley-based finishing diet where an algae meal (DHA-Gold; Schizochytrium spp.) replaced flax oil and barley grain at 0 or 3% DM (n = 6). Total RNA from each tissue was subjected to quantitative real time (qRT-) PCR analysis to determine the expression of 15 selected miRNA including 11 identified from bovine adipose tissues and 4 conserved between bovine and ovine species. MicroRNAs were differentially expressed according to diet in each tissue depot (miR-142-5p and miR-376d) in visceral and miR-142-5p, miR92a, and miR-378 in subcutaneous adipose tissue; P ≤ 0.05) and in each tissue depot depending on diet (miR-101, miR-106, miR-136, miR-16b, miR-196a-1, miR-2368*, miR-2454, miR-296, miR-376d, miR-378, and miR-92a in both control and DHA-G diets and miR-478 in control; P ≤ 0.05). Six miRNA were subjected to functional analysis and 3 genes of interest (ACSL1, PPARα, and C/EBPα) were validated by qRT-PCR. Both diet and tissue depot affected expression levels of all 3 genes (P < 0.05). miR-101, miR-106, and miR-136 were negatively correlated with their respective predicted gene targets C/ EBPα, PPARα, and ACSL1 in subcutaneous adipose tissue of lambs fed DHA-G. Yet miR-142-5p and miR-101 showed no correlation with ACSL1 or C/EBPα. The variability in expression patterns of miRNA across adipose depots reflects the tissue specific nature of adipogenic regulation. Although the examined miRNA appear to be conserved across ruminant species, our results indicate the presence of ovine specific regulatory mechanisms that can be influenced by diet.

Adipose tissue plays a critical role in energy homeostasis and metabolism. There is sparse understanding of the molecular regulation at the protein level of bovine adipose tissues, especially within different fat depots under different nutritional regimes. The objective of this study was to analyze the differences in protein expression between bovine subcutaneous and visceral fat depots in steers fed different diets and to identify the potential regulatory molecular mechanisms of protein expression. Subcutaneous and visceral fat tissues were collected from 16 British-continental steers (15.5 month old) fed a high-fat diet (7.1% fat, n=8) or a control diet (2.7% fat, n=8). Protein expression was profiled using label free quantification LC-MS/MS and expression of selected transcripts was evaluated using qRT-PCR. A total of 682 proteins were characterized and quantified with fat depot having more impact on protein expression, altering the level of 51.0% of the detected proteins, whereas diet affected only 5.3%. Functional analysis revealed that energy production and lipid metabolism were among the main functions associated with differentially expressed proteins between fat depots, with visceral fat being more metabolically active than subcutaneous fat as proteins associated with lipid and energy metabolism were upregulated. The expression of several proteins was significantly correlated to subcutaneous fat thickness and adipocyte size, indicating their potential as adiposity markers. A poor correlation (r=0.245) was observed between mRNA and protein levels for 9 genes, indicating that many proteins may be subjected to post-transcriptional regulation. A total of 8 miRNAs were predicted to regulate more than 20% of lipid metabolism proteins differentially expressed between fat depots, suggesting that miRNAs play a role in adipose tissue regulation. Our results show that proteomic changes support the distinct metabolic and physiological characteristics observed between subcutaneous and visceral adipose tissue depots in cattle.

The objective of this research was to isolate and to verify the sensitivity to antimicrobial agents of strains of Salmonella sp. isolated from poultry products in the state of Ceara, Brazil. A total number of 114 samples was collected from 63 broiler carcasses derived from two processing plants and two supermarkets, and 51 excreta samples were collected in broiler farms located in the state of Ceara, which used three live production stages. Each excreta sample consisted of a fresh excreta pool from 100 birds. Samples were submitted to microbiological analyses, and the isolated Salmonella strains were tested for antimicrobial sensitivity. No Salmonella was isolated from excreta samples, while broiler carcass samples showed a high contamination rate of11.8%. Three serotypes were identified: Salmonella enterica serovar Enteritidis, 50%; Salmonella enterica serovar Panama 33%, and Salmonella enterica serovar Newport, 17%. As to the susceptibility tests to antimicrobial agents, 100% of the isolated Salmonella strains showed resistance to Ampicillin and Tetracycline, and sensitivity to Gentamycin, Netilmycin, Carbenicillin, Chloramphenicol.