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In the current study we have performed two experiments to evaluate the effects of adipogenic induction media on dedifferentiated fat (DFAT) cells redifferentiation into mature adipocytes. In experiment 1, we aimed to evaluate whether it is necessary to use insulin in the induction media to allow DFAT cells differentiation into mature adipocytes by establishing two experimental treatments where insulin was either withdrawn from the culture medium, after 72 h of a normal induction period (Treatment 1: Insulin - ) or kept in culture media (Treatment 2: Insulin + ) for 16 d. In experiment 2, we aimed to evaluate if the lack of 3-isobutyl-1-methylxanthine (IBMX) in the induction medium would affect the differentiation of DFAT cells into mature adipocytes. For that, DFAT cells were induced to differentiate into lipid assimilating adipocytes using an induction medium containing IBMX (Treatment 1: IBMX + ) or without IBMX (Treatment 2: IBMX - ) during the first 72 h of induction. In both experiments we have evaluated the mRNA expression of lipid metabolism markers and cell morphology through Oil-Red staining as indicators of differentiation of DFAT cells into lipid-assimilating cells. The results of Experiment 1 revealed no differences in mRNA expression for any of the lipid metabolism markers with exception of GLUT4 ( P =0.02), which was greater in Insulin - compared to Insulin + treatment. Similarly, no differences were observed for mRNA expression of adipogenic markers between IBMX + and IBMX - treatments with exception of FABP4 ( P =0.01), which was greater for the IBMX - compared to IBMX + treatment. In both experiments we did not observed any differences in cell morphology among treatments. Our results suggest that neither insulin nor IBMX are required to accelerate redifferentiation process of pig-derived DFAT cells.

This study assessed the effect of myostatin on adipogenesis by porcine intramuscular preadipocytes. Intramuscular preadipocytes were isolated from the longissimus dorsi muscle of newborn pigs. Myostatin inhibited intramuscular preadipocyte differentiation in a dose-dependent manner. Myostatin treatment during preadipocyte differentiation significantly (P < 0.05) inhibited the expression of the adipogenic marker genes CCAAT/enhancer-binding protein β, CCAAT/enhancer-binding protein α, peroxisome proliferator-activated receptor γ, sterol regulatory element-binding protein-1c, fatty acid-binding protein, and adiponectin. Myostatin also significantly (P < 0.05) reduced the release of glycerol and decreased both adipose triglyceride lipase and hormone-sensitive lipase expression in intramuscular adipocytes. Our study suggests that myostatin acts as an extrinsic regulatory factor in regulating intramuscular adipogenesis.

Among several potential animal models that can be used for adipogenic studies, Wagyu cattle is the one that presents unique molecular mechanisms underlying the deposit of substantial amounts of intramuscular fat. As such, this review is focused on current knowledge of such mechanisms related to adipose tissue deposition using Wagyu cattle as model. So abundant is the lipid accumulation in the skeletal muscles of these animals that in many cases, the muscle cross-sectional area appears more white (adipose tissue) than red (muscle fibers). This enhanced marbling accumulation is morphologically similar to that seen in numerous skeletal muscle dysfunctions, disease states and myopathies; this might indicate cross-similar mechanisms between such dysfunctions and fat deposition in Wagyu breed. Animal models can be used not only for a better understanding of fat deposition in livestock, but also as models to an increased comprehension on molecular mechanisms behind human conditions. This revision underlies some of the complex molecular processes of fat deposition in animals.

This study was developed aiming to evaluate the effects of maternal feed-restriction ond evelopment of gastrointestinal tract (GIT) of bovine fetus at different gestational stages. Feed-restricted cows were fed 1.2 times the maintenance level while the control group was fed ad libitum. Pregnant cows were slaughtered at 136, 189, 239, and 269 days of gestation and gastrointestinal tracts of the fetuses were evaluated. No effects of maternal nutrition on body weight (P 1⁄4 0.17) and body length (P 1⁄40.13) of the fetuses were observed. No major effects of feed restriction on GIT mass of the fetuses were observed (P 1⁄4 0.51). However, the weight of small intestine per unit of body weight was 11.24% greater (P 1⁄40.04) in fetuses from restricted dams. Additionally, the length of small intestine and its villi were 12.93% and 16.44% respectively greater (P o .001) in fetuses from restricted dams compared to those from non-restricted dams. These data indicates that maternal feed-restriction does not affect the development of most of fetal gastrointestinal parts besides small intestine which in turn increases its surface area as a response of maternal feed restriction.

The dynamics of human and animal adipogenesis has been defined using several traditional cell systems including stromal vascular cells and adipocyte-related cell lines. But a relatively new cell system using progeny cells stemming from the dedifferentiation of purified cultures of mature adipocytes may be used for studying the development and biology of adipocytes. In this research, we show that isolated (and purified) mature adipocytes derived from Wagyu cattle dedifferentiate into progeny cells, and that these spindle-shaped, proliferative-competent daughter cells possess ability to proliferate. We outline the optimum cell culture system and offer precautionary thoughts for effective mature adipocyte culture. Collectively, this represents a novel cell model which may provide new insights into cell development, physiology and use as a model for animal production/composition, tissue engineering and disease treatment.

A 2×3 factorial experiment was conducted with 72 weanling, crossbred steers (with Hereford, Angus and Charolais genetics and initial BW of 280.5±5.8 kg) with the objective of determining the effect of dietary and feed withdrawal (FW) treatments on plasma concentrations of glucose, insulin, growth hormone (GH) and leptin and on intramuscular and subcutaneous (SQ) adipose cellularity. Supplementation was a 50/50 mixture of flax and sunflower oil at 5% of diet (OIL) versus a control (CON; without oil) diet, which were the dietary treatments and were applied to steers experiencing three feed withdrawal (FW) treatments. The FW treatments were no FW, a single 48 h FW (FW×1) before initiation of fattening at one year of age or 48 h FW at 8 week intervals from weaning to initiation of fattening (FW×4). Plasma was harvested from jugular blood collected from all steers after each FW and samples of pars costalis diaphgramatis (PCD) muscle and SQ from the brisket were collected from the steers at slaughter for adipocyte enumeration. Cell number was determined by computerized image enumeration and electronically by a particle counter. Plasma concentrations of glucose and hormones responded to age of steers at the time of sample procurement ( P =0.001–0.053), and a diet×FW interaction ( P =0.015) was observed for insulin, because steers fed the OIL diet in the FW×4 treatment had lower insulin concentrations than of those in the other FW treatments. Concentrations of growth hormone (GH) decreased ( P =0.028) due to FW from 7.17±1.02 ng/mL in steers in the no FW treatment to 5.04±0.78 and 5.46±1.22 ng/mL for steers in FW×1 and FW×4 treatments, respectively. Leptin concentrations were unaffected by diet or FW treatment. The relationship for cells enumerated by the particle counter versus the Motic computer program was significant ( P =0.01) for both PCD and SQ fat with r 2 values of 0.55 and 0.24, respectively, for total cells of diameters from 30 to 300 μm. Number of adipocytes with diameters from 80 to 140 μm in the PCD were greater ( P =0.038 and 0.028) in OIL than in CON fed steers. The percent of total number of cells in the 30–60 μm diameter range in the PCD were greater in steers in FW×1 and FW×4 than in no FW treatments when counted by either method. Provision of dietary oil and FW treatments had no effect on plasma metabolites and may be the reason for the absence of a response in total adipocyte numbers due to FW.

A 2 × 3 factorial experiment was conducted with 72 weanling (about 180 d old), crossbred steers (with Hereford, Angus and Charolais genetics and initial body weight of 280.5 ± 5.8 kg) to determine the effect of dietary supplementation with a 50/50 mixture of flax and sunflower oils at 5% of diet, to steers in three feed withdrawal (FW) treatments on production factors, carcass characteristics, adipocyte marker; peroxisome proliferator activated receptor γ (PPARγ) RNA expression and fatty acid composition of muscle ( Pars costalis diaphragmatis ; PCD) and subcutaneous fat (SQ from brisket). The FW treatments were no FW, a single 48 h FW (FW × 1) before start of fattening or 48 h FW at 8 week intervals from weaning to start of fattening (FW × 4). Individually penned steers were fed mixed hay and rolled barley diets containing no oil (Control; CON) or 5% oil (OIL) through growing, transition and fattening phases. Interaction of dietary oil and FW treatments did not affect any of the production factors. Decreased ( P = 0.008) dry matter intake (DMI) of the OIL diet was noted through the growing period; thus decreasing ( P = 0.019) total DMI by 112 kg/hd for the experiment and improved gain per unit feed ( P = 0.019) for the growing period. The FW × 1 treatment reduced ( P = 0.004) average daily gain (ADG) through the transition period, but ADG tended to improve ( P = 0.081) during fattening and steers in FW treatments gained 1.38 ± 0.07 versus 1.25 ± 0.06 kg/d for those in the no FW treatment. Differences due to dietary oil or the FW treatments were not observed for any of the carcass characteristics. A diet × FW interaction ( P = 0.001) was observed for PPARγ expression in the PCD and SQ. Adipocyte marker expression was greater in PCD of steers in the FW × 4 treatment with values for OIL fed steers being greater than of CON fed steers. Feeding the OIL diet increased ( P = 0.001) the weight percent of C18:1t10, C18:1t11, conjugated linoleic acid and n3 fatty acids by 178, 152, 66 and 32%, respectively. The n6:n3 ratio in PCD was decreased in OIL fed steers. Results indicate that repeated FW can enhance adipocyte marker expression in muscle thus improving the potential to increase marbling fat in steers, while oil, comprised of n3 and n6 fatty acids, increased biologically active fatty acids and decreased n6:n3 fatty acid ratios of tissues, without affecting productivity or carcass characteristics of the steers.

We evaluated the effects of betaine supplementation on liver weight, liver/body weight, serum parameters and morphological changes. Compared with the control and overfed groups, the geese that were fed the betaine diet showed increased liver weight and decreased abdominal adipose tissue weight compared with the overfeeding groups. Betaine treatment also significantly increased ChE, HDL, LDH and ALT levels (P

The existence of myogenic satellite cells was reported some 47 years ago, and, since that time, satellite cell research has flourished. So much new information is generated (daily) on these cells that it can be difficult for individuals to keep abreast of important issues related to their activation and proliferation, the modulation of the activity of other cell types, the differentiation of the cells to facilitate normal skeletal muscle growth and development, or to the repair of damaged myofibers. The intent of this review is to summarize new information about the extrinsic regulation of myogenic satellite cells and to provide specific mechanisms involved in altering satellite cell physiology. Where possible, examples from agriculturally important animals are used for illustrative purposes.

The effect of feed withdrawal for 48 h, prior to initiation of the finishing (fattening) period (75 d) on carcass marbling fat was studied in 120 European × British cross-bred heifers with an average weight of 585 ± 39 kg. Heifers were randomized in a 2 × 2 factorial design experiment with two dietary management treatments, where half the heifers were provided the feed components of steam rolled barley and barley silage either free choice or as a total mixed ration (TMR) containing 87% steam rolled barley and 13% barley silage with ad libitum vitamins and minerals via salt blocks for all animals. Within each dietary management treatment, 30 heifers were denied feed (water was available) for 48 h prior to the two week adaptation to the high grain diet preceding the 75 d finishing period. At the end of the 48 h feed denial blood samples were collected from the jugular vein prior to feeding for determination of glucose and insulin concentrations, which indicated that 48 h feed withdrawal consistently decreased ( P = 0.0001) plasma concentrations of both glucose and insulin but the ratios of the concentrations of glucose to insulin were not affected. At slaughter samples of subcutaneous fat from the brisket (BF) and skirt muscle ( pars costalis diaphragmatis ; PCD) were procured for determination of chemical fat content, fat dissected from the muscle and for enumeration of adipocytes, less than 35 μm in diameter and to determine the average cell size in the dissected fat and from the BF by flow-cytometry of adipocytes fixed in osmium tetroxide. The carcass characteristics were also obtained. Although no differences due feed withdrawal for 48 h were evident for carcass weight, percent lean (saleable) meat yield, rib eye area, average fat cover, fat content of PCD or BF, the US marbling score was increased ( P = 0.048) and the amount of dissected fat from the muscle tended to be higher ( P = 0.107), thus 81% of the carcasses graded “US Choice” or “Canada AAA,” or displayed at least a “small” amount of intramuscular fat as compared ( P = 0.0807) to 68% of the heifers not denied feed. Based on more than three years of weekly prices of carcasses that graded “Canada AAA” and “Canada AA,” these experimental results suggested that the expected price of a finished heifer could increase by $4.61 Canadian if a 48 h feed withdrawal was imposed prior to initiation of the finishing phase. Although significant differences in adipocyte numbers due to a single time 48 h feed withdrawal prior to initiation of the finishing phase were not detected, the carcass quality factors were affected leading to an odds ratio of 1.84 times in favour of cattle carcasses to grade “Canada AAA” than if fed continuously.

In this document, we have integrated knowledge about two major cellular markers found in cells of the adipocyte lineage (an adipogenic marker and a metabolic marker). This review provides information as to how differentiation of a cell (such as an adipofibroblast, fibroblast or preadipocyte) to become a viable (and new) adipocyte is under different regulation than that experienced by an immature adipocyte that is just beginning to accumulate lipid. The differentiation, prior to lipid-filling, involves PPARγ. Subsequently, lipid-filling of the adipocyte relies on a late subset of genes and, depending on depot specificity, involves GLUT-4 or any number of other metabolic markers.

Obesity is presently being combated by fitness regimens, drugs and diet. Increasing our understanding of the physiology of adipocytes, by deducing the regulatory pathways involved in lipid metabolism and all aspects of adipogenesis, will provide alternative strategies to reduce adverse problems of obesity. Research has suggested that mature fat cells may dedifferentiate to form proliferative-competent fat cell precursors. Knowledge of the dedifferentiation process will allow us to gain a solid grip on adipogenesis.

Adipose tissue contains a large portion of stem cells. These cells appear morphologically like fibroblasts and are primarily derived from the stromal cell fraction. Mature (lipid-filled) adipocytes possess the ability to become proliferative cells and have been shown to produce progeny cells that possess the same morphological (fibroblast-like) appearance as the stem cells from the stromal fraction. A closer examination of mature adipocyte-derived progeny cells may prove to be an emerging area of growth/metabolic physiology that may modify present thinking about adipose tissue renewal capabilities. Knowledge of these cells may also prove beneficial in cell-based therapies for tissue repair, regeneration, or engineering.

The utility of co-culture systems in defining the interactions between two different cell types has been well documented in the literature but is a relatively new tool for use in the study of cells derived from normal muscle tissue from meat animals. The majority of myonuclei in postnatal skeletal muscle cells (myofibers) result from satellite cell proliferation, differentiation and fusion with existing myofibers. As such, satellite cell culture systems that mimic postnatal myofibers have great potential for delineating the process of growth and repair of muscle mass. Other ways to simulate the environment of postnatal myofibers might include the development of co-culture systems using satellite cells, or satellite cell-derived myotubes, and other mesodermal cells commonly found associated with muscle tissue in vivo. This brief review describes our initial efforts to develop a defined satellite cell and preadipocyte co-culture system. We provide useful information about defined media requirements and requirements for proper cell orientation and growth on two different growth planes. We present summary data to suggest that differences were found between members of the insulin-like growth factor (IGF) and IGF-binding protein (IGFBP) families of polypeptides, when conditioned media samples were analyzed from co-cultures composed of 3T3-L1 preadipocytes and satellite cells (with different propensities to undergo morphological fusion to form multinucleated myotubes). We also provide information about potential problems to avoid when initiating and conducting co-culture experiments. Such a co-culture system has application in the study of human obesity and also in the regulation of fat deposition in meat animals.

The ability of ovine-derived satellite cells to attach, proliferate and differentiate in response to seven horse serum-supplemented media and eleven substrata was evaluated in vitro. Satellite cells attached equally well when exposed to CRCM-30, Medium-199 and high glucose Dulbecco's modified Eagles medium (DMEM, P less than 0.05). Proliferation of satellite cells was greatest using McCoy's 5A, supplemented with 15% horse serum (P less than 0.05), and differentiation was most efficient with low glucose DMEM, supplemented with 1% horse serum (P less than 0.05). Pig-skin gelatin facilitated the greatest ovine satellite cell proliferative and differentiative responses when compared to the performance of ten other substrata (P less than 0.05). Further, 0.5 mg/16 mm2-well pig-skin gelatin appeared to be the optimum concentration of substratum for expression of satellite cell growth characteristics. Thus, consideration must be given to the processes of attachment and proliferation in experiments attempting to maximize satellite cell differentiation in vitro.

Ability to assess how solidly one is participating in their research arena is a metric that is of interest to many persons in academia. Such assessment is not easily defined, and differences exist in terms of which metric is the most accurate. In reality, no single production metric exists that is easy to determine and acceptable by the entire scientific community. Here we propose the SP-index to quantify the scientific production of researchers, representing the product of the annual citation number by the accumulated impact factors of the journals whereby the papers appeared, divided by the annual number of published papers. This article discusses such a productivity measure and lends support for the development of unified citation metrics for use by all participating in science research or teaching.

Molecular mechanisms of peroxisome proliferator activated receptors (PPARs) are being defined rapidly, as illustrated by the volume of papers published. Much of the research is directed towards a clinical end-point/application; however, the non-homogeneous nature of adipose depots in laboratory animals is spurring similar research in domestic meat animals (such as beef cattle). Moreover, the size of adipose depots in meat animals remains an attractive feature for using them to obtain cells for PPAR research. Examination of meat-animal depot-specific PPAR moieties may provide novel information about adipocyte regulation that might be extrapolated to all animals.

Ovine-derived fibroblasts were used to validate an insulin-like growth factor I (IGF-I) membrane-receptor binding assay system. Competitive binding using fibroblasts revealed that half-maximal inhibition of 125I-IGF-I binding by IGF-I was 2.3 nM. SDS-polyacrylamide gel electrophoresis analysis of specific protein-associated 125I-IGF-I was consistent with the migration of 125I-IGF-I-labeled Type I IGF receptor alpha-subunits at Mr 133,000 daltons. Further, the efficiency of two cell solubilization methods was examined and time-dependent binding equilibrium was determined for the membrane assay system. Satellite cell-derived myotubes were subsequently isolated from primary satellite cell cultures established from the semimembranosus muscles of high and low efficiency-of-gain (EOG) Targhee rams, and IGF-I receptor dynamics were measured. A membrane competitive binding study revealed that half-maximal inhibition of 125I-IGF-I binding was achieved by 1-ng IGF-I for low, and 10-ng IGF-I for high, EOG myotube membrane preparations. Kd values were similar between the high EOG (4.78 nM) and low EOG (2.95 nM) groups; however, receptor concentrations (Bmax) appeared to differ between groups. High EOG membrane receptor Bmax was 3.88 pmole/micrograms protein (19.87 pmole/micrograms DNA), whereas low EOG membrane receptor Bmax was 1.22 pmole/micrograms protein (9.28 pmole/micrograms DNA). These preliminary findings support the hypothesis that genetic selection for EOG results in altered satellite cell responsiveness to IGF-I.

Myogenic satellite cells were isolated from nondiabetic and streptozotocin-diabetic rats and studied in vitro. Streptozotocin (STZ) administration produced both hyperglycemia and glucosuria in adult rats when compared to controls. (P less than 0.01), with 12.5% mortality in untreated animals. Insulin therapy diminished blood glucose levels to those found in nondiabetic animals. Only STZ-diabetic rats displayed symptoms of Type I diabetes, including polydipsia, polyuria, and hyperphagia. STZ-treated rats possessed less leg muscle mass and less subcutaneous, intermuscular, and intramuscular fat. Conversely, nondiabetic rats had a greater mean body weight (P less than 0.01) at the end of the experiment than did diabetic rats. Primary cultures of diabetic-derived satellite cells displayed decreased overall ability (P less than 0.01) to fuse to form multinucleated myotubes in vitro than controls. In addition, secondary cultures of diabetic-derived satellite cells achieved maximal fusion one day later than secondary cultures of control-derived cells. Collectively, these data provide preliminary evidence to suggest that untreated insulin-dependent diabetes results in altered fusion characteristics of myogenic satellite cells. Additional studies utilizing satellite cells from diabetic animals will provide valuable definition of the satellite cell involvement in skeletal muscle autophagy which is a symptom of type I diabetes.

Post-natal myogenic satellite cells, isolated from the sternomandibularis muscles of bovine at slaughter were used for primary culture studies. Isolated satellite cells tended to differentiate into multinucleated myotubes more efficiently if initially plated on to a fibronectin substratum. Bovine-derived satellite cells displayed greater fused cell numbers when exposed to Dulbecco's Modified Eagle's Medium (DMEM) supplemented with horse serum than similar supplementation with fetal calf serum (P less than 0.05) or sheep serum (P less than 0.05). In addition, differentiation appeared nearly complete after 4 days exposure to DMEM-1% horse serum as verified by beta-D-arabinofuranosyl-cytosine addition to cultures. Collectively, these data provide the first evidence that satellite cells can be isolated from a bovine skeletal muscle. Furthermore, these data indicate that bovine-derived satellite cells can be induced to undergo substantial morphological differentiation in vitro.