C/EBPb converts bovine fibroblasts to adipocytes without hormone cocktail induction

BACKGROUND: Adipogenesis and fibrogenesis can be considered as a competitive process in muscle, which may affect the intramuscular fat deposition. The CCAAT/enhancer-binding protein beta (C/EBPb) plays an important role in adipogenesis, which is well-characterized in mice, but little known in bovine so far. RESULTS: In this study, real-time qPCR revealed that the level of C/EBPb was increased during the developmental stages of bovine and adipogenesis process of preadipocytes. Overexpression of C/EBPb promoted bovine fibroblast proliferation through mitotic clonal expansion (MCE), a necessary process for initiating adipogenesis, by significantly downregulating levels of p21 and p27 (p < 0.01). Also, the PPARc expression was inhibited during the MCE stage (p < 0.01). 31.28% of transfected fibroblasts adopted lipid-laden adipocyte morphology after 8 d. Real-time qPCR showed that C/EBPb activated the transcription of early stage adipogenesis markers C/EBPa and PPARc. Expression of ACCa, FASN, FABP4 and LPL was also significantly upregulated, while the expression of LEPR was weakened. CONCLUSIONS: It was concluded C/EBPb can convert bovine fibroblasts into adipocytes without hormone induction by initiating the MCE process and promoting adipogenic genes expression, which may provide new insights into the potential functions of C/EBPb in regulating intramuscular fat deposition in beef cattle.

Availability of multi-frequency impedance method for evaluating of intramuscular fat : Echo intensity calculated from skeletal muscle images as a comparative control / 体力科学

In this study, we performed echo intensity obtained from ultrasonographic images was used as a reference for intramuscular fat mass to determine whether intramuscular fat can be estimated non-invasively using the bioelectrical impedance method. The subjects were 45 healthy male university students (mean age 20.2±1.4 years) of the athletic club. An ultrasound images were taken from vastus lateralis, and the echo intensity was calculated from the obtained image using image analysis software. The impedance corresponding to each of the 17 points from 4to 700 kHz were collected using a multi-frequency impedance measuring device. In addition, intracellular resistance and extracellular resistance were calculated using Cole-Cole distribution model. Pearson’s correlation coefficient was used for the relationship between echo intensity and impedance. As a result, when using a frequency of 50 kHz or more, we observed a moderate correlation (r=0.529 ~ 0.597, p<0.001) between an impedance of 2cm at the distance between the sensing (V) and current (I) electrodes and echo intensity at 2cm from the skin surface. A moderate correlation (r=0.551, p<0.001) was observed between the intracellular resistance at the V-I electrode spacing of 2cm and echo intensity at 2cm form the skin surface. However, there was only a weak correlation between extracellular resistance and echo intensity. This suggests that the impedance and intracellular resistance measured at a frequency of 50 kHz or higher and with a V-I electrode spacing of 2cm reflect intramuscular fat.

Changes in adipose cells of Longissimus dorsi muscle in Iberian pigs raised under extensive conditions

ABSTRACT Twenty-four Iberian castrated male pigs were used to characterize and evaluate the effect of the duration of "Montanera" in the adipocytes size and its relation with the backfat thickness and intramuscular fat. The animals were fed under extensive conditions during 30, 60 and 90 days in the "Dehesa" before slaughtered. Carcass weight, percentage of intramuscular fat, thickness of backfat and its three layers and adipocytes size of the intramuscular fat were obtained. The group which expended 90 days on fattening obtained the highest adipocytes, with an area higher by a 50% than those that only expended 30 days. The differences in diameter and perimeter adipocyte were not as marked as area. A significant positive correlation between the diameter, area and perimeter of adipocyte with the backfat thickness were found. The fat cells in Iberian pig hypertrophy during the "montanera stage", being this increase significant from month to month in this period of fattening. Also, this adipocyte increase is correlated with the animal weight. The correlation between adipocyte size and inner layer of backfat shows that the inner layer obtained in live pig by ultrasound techniques could be a good marker of fat infiltration in pigs fattening in "montanera" system.

Generation of transgenic rabbits expressing swine PID1 by testicular injection / 中国实验动物学报

Objective The aim of this study was to investigate the relationship between phosphotyrosine interac-tion domain containing 1 ( PID1 ) gene and variation in intramuscular fat ( IMF ) content and the possibility to generate transgenic animals by testicular injection .Methods Expression vector pIRES2-acGFP-PID1 carrying pig PID1 gene was incubated with transfection reagents and injected into the testes of male New Zealand rabbits .We examined the F1 genera-tion by fluorescence detection , PCR, Western blotting and measuring the IMF content .The F1 generation gave birth to the F2 generation.Then we examined the F2 generation through detecting the positive rate and the IMF content .Results The exogenous PID1 gene and fluorescent protein gene were expressed at different levels both in the F 1 generation and the F2 generation, and the positive rates were 35.88%and 34.33%, respectively.The IMF content was significantly elevated (P<0.05) in the transgenic positive individuals compared with the negative ones and the control group , and the PID1 protein expression was similarly higher .Conclusions The results of this study demonstrate that PID 1 gene affects intramuscular fat content significantly .Moreover, the results of our analysis provide further evidence that transgenic animals can be gener -ated by testicular injection , and the exogenous gene can be inherited steadily .

Carcaça e carne de novilhos cruzas Pardo Suíço x Canchim e Purunã x Canchim terminados em confinamento / Feedlot performance and carcass and meat traits of crossbred Braunvieh x Canchim and Purunã x Canchim

O trabalho teve os objetivos de avaliar o desempenho em confinamento e as características da carcaça e da carne de novilhos inteiros dos grupos genéticos ½ Pardo Suíço + ½ Canchim (1B1C), ½ Purunã + ½ Canchim (1P1C) e ¾ Purunã + » Canchim (3P1C). Foram utilizados 23 novilhos inteiros com idade média de 22 meses, que permaneceram confinados por 145 dias. O aumento da proporção de genes Purunã na composição racial dos animais de 50 por cento para 75 por cento no cruzamento com Canchim resultou em incrementos de peso no abate (PA) e de ganho de peso (GMD) de 10,6 e, 12,1 por cento, respectivamente. Os animais 1B1C apresentaram PA e GMD semelhantes aos animais 3P1C e superiores aos animais 1P1C. O consumo de matéria seca (MS) e o GMD não diferiram entre animais dos grupos 1B1C e 3P1C, ambos apresentando consumo e GMD superiores aos dos animais 1P1C (8,87; 7,97 e 7,02kg de MS animal-1 dia-1, e, 1,62; 1,41 e 1,58kg animal-1 dia-1, respectivamente). Animais 1B1C e 3P1C apresentaram carcaças 12,1 por cento mais pesadas que os animais 1P1C. A conformação da carcaça dos animais 1B1C foi superior (15,0 pontos) em relação aos 1P1C e 3P1C (13,2 e 13,6 pontos, respectivamente). Animais 1B1C e 3P1C demonstraram valores similares para marmoreio da carne (7,5 e 6,6 pontos, respectivamente), e superiores em relação ao 1P1C (4,8 pontos). A produção de animais F1 Pardo Suíço x Canchin é mais interessante ao produtor, devido à maior velocidade de ganho de peso e maior peso de carcaça, ao frigorífico, por obter carcaças de melhor conformação e grau de acabamento, e ao consumidor, por apresentar maior grau de marmorização da carne e textura mais fina.

The research had the objectives of evaluating feedlot performance as well as carcass and meat traits of 23 young bulls from three genetic groups: ½ Braunvieh + ½ Canchim (1B1C), ½ Purunã + ½ Canchim (1P1C) and ¾ Purunã + » Canchim (3P1C). The experimental animals were 22 months old, on average, at the beginning and remained in total confinement during 145 days. The increase in the proportion of Purunã gens, from 50 percent to 75 percent, in the cross with Canchim, brought about increment of slaughter weight (SW) and weight gain (GW) of 10.6 and, 12.1 percent, respectively. Animals 1B1C were superior to the 1P1c animals and similar to the 3P1C ones with respect to SW and GW. Likewise, the feed intake and GW were similar between animals of the1B1C and 3P1C, both being superior to the ½ P + ½ C animals. (8.87, 7.97 and 7.02kg animal-1 day-1; and, 1.62, 1.41 and 1.58kg animal-1 day-1, respectively). The 1B1C and 3P1C animals produced carcasses weighing 12.1 percent more than those of the 1P1C animals. Better carcass conformation scores were observed for the 1B1C animals in comparison to those from the1P1C and 3P1C ones. The group averages for this trait were 15.0 points versus 13.2 and 13.6 points, respectively. The 1B1C and 3P1C groups had similar averages for marbling score of the meat (7.5 and 6.6 points, respectively), both being superior to the ½ P + ½ C group that had an average marbling score of 4.8 points. The production of F1 Braunvieh x Canchim animals is advantageous for the entire beef cattle production chain. The producer benefits because these animals yield heavier carcass weight; the slaughter plants also gain with the better carcass conformation and degree of finish; and, finally, the consumer because the meat of these animals has better marbling and texture scores.