A method to establish co-cultures of myotubes and preadipocytes from collagenase digested neonatal pig semitendinosus muscles

The relationships between adipocyte and muscle cell development within muscle are important in the study of factors or agents that may improve meat quality. Neonatal porcine muscle has the potential to yield both cell types for cell culture because it contains developing adipocytes and a high number of muscle satellite cells. Therefore, we modified a conventional collagenase-based procedure to digest neonatal porcine muscle and subsequently cultured the resultant muscle stromal-vascular (SV) cells on several substrata in basal and dexamethasone (DEX)-containing media. Developing myotubes and preadipocytes were present in muscle SV cell cultures on laminin substrata following seeding and plating with fetal bovine serum (FBS) with or without DEX. Myotube number was much higher (P < 0.05) on laminin substrata compared with all other substrata, whereas preadipocyte number in muscle SV cell cultures was independent of substrata, as we have shown previously. This approach can be used to establish co-cultures of differentiating adipocytes and myotubes from collagenase-digested neonatal pig muscle. Because the comparison is within the same culture dish, this method allows for a direct comparison of the responses of adipogenic and myogenic cells to growth and differentiation factors. For example, DEX did not alter myogenesis (i.e., 11 +/- 3 vs. 11 +/- 4 myotubes per unit area for control and DEX-treated cultures, respectively), but it has been shown to markedly increase preadipocyte number in muscle SV cell cultures.     

Abundance and survival of infective larvae of the cattle nematodes Cooperia punctata, Haemonchus placei and Oesophagostomum radiatum from faecal pats in a wet tropical climate

Observations were made on the abundance and survival of Haemonchus placei, Cooperia punctata and Oesophagostomum radiatum infective larvae from cattle faecal pats exposed at various times of the year in north Queensland wet tropics. Pats exposed in the hot, wet season yielded abundant larvae on herbage. In the dry season, although low numbers of infective larvae were usual, considerable numbers were produced under conditions of heavy dews on dense herbage. Irrespective of season of deposition of pats, the resulting larvae persisted generally for not longer than 10 to 12 weeks, and in large numbers for only 2 to 6 weeks. The findings suggest that prevention of contamination in the wet season, and in the dry season when light rainfalls are accompanied by heavy dews on dense herbage, will result in low levels of larval infestation on herbage. Rotational grazing in the area is suggested as a means of worm control.     

The influence of insulin, triiodothyronine (T3) and insulin-like growth factor-I (IGF-1) on the differentiation of preadipocytes in serum-free cultures of pig stromal-vascular cells

Adipose tissue stromal-vascular (S-V) cells were obtained from 1-d-old pigs by enzymatic digestion and then grown to confluence (1 to 4 d) in 10% fetal bovine serum. Cultures then were shifted to serum-free media for 7 d. One and 50 nM insulin with transferrin (5 micrograms/ml) significantly increased (P less than .05) the cytodifferentiation of preadipocytes in serum-free cultures of S-V cells compared with control cultures (no hormones). Fifty nanomolar and 1 microM insulin with transferrin increased the specific activity of glycerol-phosphate dehydrogenase (GPDH) and the soluble protein levels of S-V cultures compared with control cultures. Ten nanomolar insulin-like growth factor-1 (IGF-1) increased (P less than .05) GPDH specific activity, soluble protein and preadipocyte cytodifferentiation compared with control cultures. Triiodothyronine (T3) supplementation (2 to 10 nM) increased (P less than .05) GPDH specific activity and increased lipid droplet size in preadipocytes compared with control cultures (no T3 but with insulin and transferrin). Cytodifferentiation of preadipocytes and soluble protein levels were not enhanced by T3 supplementation. Furthermore, T3 did not influence any parameters when added to S-V cultures that did not contain insulin. These data demonstrate that physiological levels of insulin or IGF-I can stimulate porcine preadipocyte differentiation in the absence of other hormones or growth factors.     

Effect of selection for backfat thickness in swine on fetal skeletal muscle metabolism

At 110 d of gestation, fetuses were removed from sows selected for high (obese) or for low (lean) backfat thickness. The body weights of lean (1,031 +/- 64 g) and obese (864 +/- 55 g) fetuses were not significantly different. Analysis of muscle composition and of in vitro metabolic characteristics was conducted on the biceps femoris muscle. The percentage of dry weight, protein and glycogen was greater in the muscle of obese fetuses than in the muscle of lean fetuses (P less than .01, P less than .05, and P less than .05, respectively). Percentage of muscle triglyceride was similar (P greater than .05) between the two phenotypes. The rate of glucose oxidation to CO2 tended to be greater (P less than .07) and the rate of lactate production was lower (P less than .05) in the muscle from obese fetuses than in the muscle from lean fetuses. The rates of leucine oxidation to CO2 and of palmitate oxidation to CO2 did not differ between phenotypes. The rate of alpha-ketoisocaproate release from the muscle of obese fetuses was greater (P less than .05) than from that of the lean fetuses. The rate of release of alanine and of glutamine plus glutamate did not differ between phenotypes. The rate of esterification of palmitate did not differ between phenotypes. It was concluded that abnormalities in glucose metabolism and in the partitioning of leucine between oxidation and release as the keto acid existed at 110 d of gestation in the muscle of obese fetuses. Any relation between these differences and ultimate differences in carcass composition were not evident.     

Thermal Structure of Jupiter's Upper Atmosphere Derived from the Galileo Probe

Temperatures in Jupiter's atmosphere derived from Galileo Probe deceleration data increase from 109 kelvin at the 175-millibar level to 900 ± 40 kelvin at 1 nanobar, consistent with Voyager remote sensing data. Wavelike oscillations are present at all levels. Vertical wavelengths are 10 to 25 kilometers in the deep isothermal layer, which extends from 12 to 0.003 millibars. Above the 0.003-millibar level, only 90- to 270- kilometer vertical wavelengths survive, suggesting dissipation of wave energy as the probable source of upper atmosphere heating.     

Gravity Waves in Jupiter's Thermosphere

The Atmosphere Structure Instrument on the Galileo probe detected wavelike temperature fluctuations superimposed on a 700-kelvin temperature increase in Jupiter's thermosphere. These fluctuations are consistent with gravity waves that are viscously damped in the thermosphere. Moreover, heating by these waves can explain the temperature increase measured by the probe. This heating mechanism should be applicable to the thermospheres of the other giant planets and may help solve the long-standing question of the source of their high thermospheric temperatures.     

Board-invited review: the biology and regulation of preadipocytes and adipocytes in meat animals

The quality and value of the carcass in domestic meat animals are reflected in its protein and fat content. Preadipocytes and adipocytes are important in establishing the overall fatness of a carcass, as well as being the main contributors to the marbling component needed for consumer preference of meat products. Although some fat accumulation is essential, any excess fat that is deposited into adipose depots other than the marbling fraction is energetically unfavorable and reduces efficiency of production. Hence, this review is focused on current knowledge about the biology and regulation of the important cells of adipose tissue: preadipocytes and adipocytes.     

Antioxidant profiling of native Andean potato tubers (Solanum tuberosum L.) reveals cultivars with high levels of beta-carotene, alpha-tocopherol, chlorogenic acid, and petanin

The antioxidant profile of 23 native Andean potato cultivars has been investigated from a human nutrition perspective. The main carotenoid and tocopherol compounds were studied using high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD) and a fluorescence detector, respectively, whereas polyphenols (including anthocyanins in colored tubers) were identified by means of both HPLC-mass spectrometry and HPLC-DAD. Antioxidant profiling revealed significant genotypic variations as well as cultivars of particular interest from a nutritional point of view. Concentrations of the health-promoting carotenoids, lutein and zeaxanthin, ranged from 1.12 to 17.69 microg g(-1) of dry weight (DW) and from 0 to 17.7 microg g(-1) of DW, with cultivars 704353 and 702472 showing the highest levels in lutein and zeaxanthin, respectively. Whereas beta-carotene is rarely reported in potato tubers, remarkable levels of this dietary provitamin A carotenoid were detected in 16 native varieties, ranging from 0.42 to 2.19 microg g(-1) of DW. The amounts of alpha-tocopherol found in Andean potato tubers, extending from 2.73 to 20.80 microg g(-1) of DW, were clearly above the quantities generally reported for commercial varieties. Chlorogenic acid and its isomers dominated the polyphenolic profile of each cultivar. Dark purple-fleshed tubers from the cultivar 704429 contained exceptionally high levels of total anthocyanins (16.33 mg g(-1) of DW). The main anthocyanin was identified as petanin (petunidin-3-p-coumaroyl-rutinoside-5-glucoside). The results suggest that Andean potato cultivars should be exploited in screening and breeding programs for the development of potato varieties with enhanced health and nutritional benefits.     

Andean potato cultivars (Solanum tuberosum L.) as a source of antioxidant and mineral micronutrients

Potato tubers were evaluated as a source of antioxidants and minerals for the human diet. A genetically diverse sample of Solanum tuberosum L. cultivars native to the Andes of South America was obtained from a collection of nearly 1000 genotypes using microsatellite markers. This size-manageable collection of 74 landraces, representing at best the genetic diversity among potato germplasm, was analyzed for iron, zinc, calcium, total phenolic, total carotenoid, and total vitamin C contents. The hydrophilic antioxidant capacity of each genotype was also measured using the oxygen radical absorbance capacity (ORAC) assay. The iron content ranged from 29.87 to 157.96 microg g-1 of dry weight (DW), the zinc content from 12.6 to 28.83 microg g-1 of DW, and the calcium content from 271.09 to 1092.93 microg g-1 of DW. Total phenolic content varied between 1.12 and 12.37 mg of gallic acid equiv g-1 of DW, total carotenoid content between 2.83 and 36.21 microg g-1 of DW, and total vitamin C content between 217.70 and 689.47 microg g-1 of DW. The range of hydrophilic ORAC values was 28.25-250.67 micromol of Trolox equiv g-1 of DW. The hydrophilic antioxidant capacity and the total phenolic content were highly and positively correlated (r = 0.91). A strong relationship between iron and calcium contents was also found (r = 0.67). Principal component analysis on the studied nutritional contents of the core collection revealed that most potato genotypes were balanced in terms of antioxidant and mineral contents, but some of them could be distinguished by their high level in distinct micronutrients. Correlations between the micronutrient contents observed in the sample and the genetic distances assessed by microsatellites were weakly significant. However, this study demonstrated the wide variability of health-promoting micronutrient levels within the native potato germplasm as well as the significant contribution that distinct potato tubers may impart to the intake in dietary antioxidants, zinc, and iron.