Determination of maternal pedigree and ewe-lamb spatial relationships by application of Bluetooth technology in extensive farming systems.

The objectives of this study were to validate the application of Bluetooth technology to determine maternal pedigree and to determine ewe-lamb spatial relationships in extensive farming systems. A total of 35 first-cross Merino ewes (Merino × Border Leicester and East Friesian) and 23 of their lambs aged 1 to 3 wk were fitted with activity monitors equipped with Bluetooth (BT) technology (ActiGraph wGT3X-BT) by means of halters and collars, respectively. The BT devices on lambs were programmed to receive wireless signals once every minute from nearby BT units on ewes, which were programmed as beacons sending BT signals 4 times every second. Ewes and lambs fitted with sensors were dispatched into the paddocks, and after 10 d, the sensor units were retrieved and the BT signals received by lambs were downloaded using the ActiGraph software. The maternal pedigree of the lambs was determined as the ewe from which the lamb received the most BT signals. The distance between the lamb receiving the signal and the ewe sending the signal was estimated from the strength of BT signal received. The pedigree determined by BT was compared with the pedigree determined by DNA profiling and verification. The results showed that the accuracy of maternal pedigree determined by BT signals reached 100% within the first 15 min of returning animals to pasture of ewes and lambs fitted with sensors. Maternal signals (counts/d) received by 1-, 2-, and 3-wk-old lambs were 617 ± 102, 603 ± 54, and 498 ± 36, respectively, and the corresponding nonmaternal signals received were 140 ± 27, 106 ± 30, and 155 ± 39, respectively. Maternal signals received during the dark period were significantly higher than the maternal signals received during the light period ( < 0.05). Maternal signals received during the light period by 3-wk-old lambs were significantly lower when compared with those received by 1- and 2-wk-old lambs. Over 90% of the BT signals received from within 2 m of the lamb were from its mother. The maternal BT signals expressed as a portion of total BT signals decreased with increasing distance from the lamb. The results show that BT wireless networking is a fast and reliable method for the determination of maternal pedigree of lambs in extensive farming systems. In addition, wireless BT technology is also useful in determining mother-offspring spatial relationships.

Comparison and analysis of Wuding and avian chicken skeletal muscle satellite cells.

Chicken skeletal muscle satellite cells are located between the basement membrane and the sarcolemma of mature muscle fibers. Avian broilers have been genetically selected based on their high growth velocity and large muscle mass. The Wuding chicken is a famous local chicken in Yunnan Province that undergoes non-selection breeding and is slow growing. In this study, we aimed to explore differences in the proliferation and differentiation properties of satellite cells isolated from the two chicken breeds. Using immunofluorescence, hematoxylin-eosin staining and real-time polymerase chain reaction analysis, we analyzed the in vitro characteristics of proliferating and differentiating satellite cells isolated from the two chicken breeds. The growth curve of satellite cells was S-shaped, and cells from Wuding chickens entered the logarithmic phase and plateau phase 1 day later than those from Avian chicken. The results also showed that the two skeletal muscle satellite cell lines were positive for Pax7, MyoD and IGF-1. The expression of Pax7 followed a downward trend, whereas that of MyoD and IGF-1 first increased and subsequently decreased in cells isolated from the two chickens. These data indicated that the skeletal muscle satellite cells of Avian chicken grow and differentiate faster than did those of Wuding chickens. We suggest that the methods of breeding selection applied to these breeds regulate the characteristics of skeletal muscle satellite cells to influence muscle growth.

1-Sarcosine-angiotensin II infusion effects on food intake, weight loss, energy expenditure, and skeletal muscle UCP3 gene expression in a rat model.

BACKGROUND: There are a myriad of proteins responsible for modulation of expenditure of energy. Angiotensin II (Ang II) is a vital component of renin-angiotensin system that affects blood pressure and also linked to both cachexia and obesity via fat and muscle metabolism. Previous research suggests that the direct action of Ang II is on the brain, via angiotensin II type 1 receptor protein, affecting food intake and energy expenditure. The objective of the study is to investigate the effect of 1-sarcosine (SAR)-Ang II infusion on energy expenditure and metabolism in a rat model of congestive heart failure cachexia. METHODS: Adult female rats of the Sprague Dawley strain (n = 33) were used (11 pair-fed control, 12 ad libitum and 10, 1-sarcosine-angiotensin II-infused rats). Body weight, faecal excretion, feed intake (in grams), water intake (in milliliters) and urine excreted were recorded daily. The measurements were recorded in three different periods (4 days prior to surgery, "pre-infusion"; day of surgery and 5 days postsurgery, "infusion period"; days 7 to 14, "recovery" period). Different analytical methods were used to measure energy expenditure per period, uncoupling protein 3 mRNA expression, crude protein and adipose tissue body composition. RESULTS: During the infusion period, the SAR-Ang II group experienced rapid weight loss (p < 0.05) in comparison to the ad libitum and pair-fed groups. The SAR-Ang II group displayed lower (p < 0.05) body fat content (in percent) than the controls. There was also increased (p < 0.05) uncoupling protein 3 (UCP3) mRNA expression in the SAR-Ang II group and pair-fed group when compared to the controls. CONCLUSION: In summary, the results suggest that SAR-Ang II infusion impairs appetite and decreases body weight by wasting predominantly adipose tissue, which may be due to elevated energy expenditure via mitochondrial uncoupling (UCP3 protein activity).

Angiotensin-converting enzyme inhibition reverses diet-induced obesity, insulin resistance and inflammation in C57BL/6J mice.

AIM: Angiotensin-converting enzyme (ACE) inhibition can reduce the body weight of mice maintained on a high-fat diet. The current study examined the effect of the ACE inhibitor, captopril (CAP), on the reversal of diet-induced obesity (DIO), insulin resistance and inflammation in mice. MATERIALS AND METHODS: DIO was produced in C57BL/6J male mice (n=30) by maintaining animals on a high-fat diet (w/w 21% fat) for 12 weeks. During the subsequent 12-week treatment period, the animals were allowed access to the high-fat diet and either water containing CAP (0.05 mg ml(-1)) or plain tap water (CON, control). RESULTS: From the first week of treatment, food intake and body weight decreased in CAP-treated mice compared with CON mice. Both peripheral insulin sensitivity and hepatic insulin sensitivity were improved in CAP-treated mice compared with CON mice. CAP-treated mice had decreased absolute and relative liver and epididymal fat weights compared with CON mice. CAP-treated mice had higher plasma adiponectin and lower plasma leptin levels than CON mice. Relative to CON mice, CAP-treated mice had reduced adipose and skeletal muscle monocyte chemoattractant protein 1 (MCP-1), adipose interleukin-6 (IL-6), toll-like receptor 4 (TLR4) and uncoupling protein 2 (UCP2) mRNA expressions. Furthermore, CAP-treated mice had increased peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), long chain acyl-CoA dehydrogenase (LCAD), hormone sensitive lipase (HSL) and decreased lipoprotein lipase (LPL) mRNA expressions in the liver. CONCLUSION: The results of the current study indicate that in mice with DIO, CAP treatment reduced food intake and body weight, improved insulin sensitivity and decreased the mRNA expression of markers of inflammation. Thus, CAP may be a viable treatment for obesity, insulin resistance and inflammation.

The polymorphisms of UCP1 genes associated with fat metabolism, obesity and diabetes.

Uncoupling protein 1 (UCP1), a 32-kDa protein located in the inner mitochondrial membrane, is abundant in brown adipose tissue, as a proton transporter in mitochondria inner membrane which uncouples oxidative metabolism from ATP synthesis and dissipates energy through the heat. UCP1 has been reported to play important roles for energy homeostasis in rodents and neonate of larger mammals including human. Recently, numerous candidate genes were searched to determine the genetic factors implicated in the pathogenesis of obesity, related metabolic disorders and diabetes. UCP-1, which plays a major role in thermogenesis, was suggested to be one of the candidates. This review summarizes data supporting the existence of brown adipocytes and the role of UCP1 in energy dissipation in adult humans, and the genetic variety association with the fat metabolism, obesity and diabetes.

The polymorphisms of UCP2 and UCP3 genes associated with fat metabolism, obesity and diabetes.

Uncoupling proteins (UCPs) belong to the family of mitochondrial transporter proteins that may uncouple the transport of protons across the inner mitochondrial membrane from electron transport and the synthesis of ATP from ADP, hence generating heat rather than energy. In mammals, more than five family members have been identified, including UCP1, UCP2, UCP3, UCP4 (or BMCP1/UCP5) and UCP5. The UCPs may play an important role in energy homeostasis and have become prominent in the fields of thermogenesis, obesity, diabetes and free-radical biology and have been considered candidate genes for obesity and insulin resistance. They have been as important potential targets for treatment of aging, degenerative diseases, diabetes and obesity. Recently, a series of studies showed the polymorphisms of UCPs gene association with the fat metabolism, obesity and diabetes. This review summarizes data supporting the roles of UCP2 and UCP3 in energy dissipation, as well as the genetic variety association with fat metabolism, obesity and diabetes in humans.

Cell signalling and the hormonal stimulation of the hepatic glycine cleavage enzyme system by glucagon.

The glycine cleavage enzyme system (GCS) is found in mitochondria. In liver it is activated by glucagon and other hormones but it is not known how the hormonal signal is transmitted to the mitochondria. We found that the cell-permeant protein phosphatase inhibitor okadaic acid stimulated flux through GCS and could induce a significant increase in the sensitivity of GCS and of glycogenolysis to glucagon. Half-maximal stimulation of GCS by glucagon occurred at 3.2+/-0.6 nM, whereas it was fully activated at 0.3 nM in the presence of 1 microM okadaic acid. The protein kinase A agonist adenosine-3',5'-cyclic monophosphorothioate, Sp isomer (10 microM) stimulated the GCS flux by approx. 100%. This stimulation was inhibited by the protein kinase A antagonist 8-bromoadenosine-3', 5'-cyclic monophosphorothioate, Rp isomer (Rp-8-Br-cAMPS). Although Rp-8-Br-cAMPS significantly inhibited glucagon-stimulated glycogenolysis it had no effect on the glucagon-stimulated GCS flux. These results indicate that a cytoplasmic phosphorylated protein is involved in transmitting glucagon's effect to the mitochondria. However, protein kinase A does not have a necessary role in transmitting glucagon's signal. We also examined the role of protein kinase C because angiotensin II also stimulated flux through GCS. However, the phorbol ester PMA had no effect on either GCS or on glycogenolysis.

Uptake and metabolism of propionate in the liver isolated from sheep treated with glucagon.

The uptake and metabolism of propionate in the isolated perfused caudal lobe of the liver and in isolated hepatocytes were examined following treatment of sheep with glucagon or saline. Glucagon or sterile saline was infused at 9.8 micrograms/min for 3 h into the jugular vein and then the caudal lobe of the liver was removed surgically under anaesthesia. The caudal lobe was used either to prepare hepatocytes or in a non-recirculating perfusion experiment. Uptake and metabolism of propionate were studied using [2-14C]propionate. In studies using the non-recirculation perfusion of the caudal lobe of the sheep liver it was shown that the treatment of sheep with glucagon resulted in an increased rate of gluconeogenesis from propionate and in an increased net uptake of propionate by the caudal lobe. The uptake of propionate into the hepatocytes was saturable, concentrative and exhibited a K(m) for propionate of 0.24 (SE 0.07) mM and a maximal rate of uptake (Vmax) of 6.7 (SE 0.6) nmol/mg dry cells per min and was unaffected by glucagon treatment of sheep. After incubation of cells in medium containing 0.5 mM-[2-14C]propionate for 10 min, the rate of gluconeogenesis from propionate was 22% higher in the hepatocytes isolated from glucagon-treated sheep. Concentrations in the medium of 1.35 mM butyrate and 1 mM-caproate inhibited propionate uptake by about 50% and abolished the glucagon-induced stimulation of gluconeogenesis from propionate. The results are consistent with a regulatory role for glucagon in the gluconeogenesis from propionate in the sheep liver.

Regulation of glycine catabolism in rat liver mitochondria.

1. The catabolism of glycine was studied in isolated rat liver mitochondria by measuring release of 14CO2 from [1-14C]-glycine. Incubation of mitochondria in a medium containing 0.5 microM free Ca2+ resulted in an 8-fold increase in the rate of degradation of glycine. Intraperitoneal injection of glucagon (33 or 100 micrograms/100 g body wt.) 25 min before killing of rats also resulted in a 3-fold or 10-fold (depending on dosage) increase in the rate of catabolism of glycine. 2. Both the stimulation by free Ca2+ and that by injection of glucagon in vivo were dependent on phosphate in the incubation medium. This requirement for phosphate was specific, as replacement of phosphate by other permeant anions such as thiocyanate and acetate did not permit the stimulation. The phosphate-dependent stimulation of glycine catabolism by Ca2+ was also evident when mitochondria were incubated in the absence of K+. 3. Mitochondria isolated from rats previously injected with glucagon showed elevated rates of degradation of glycine even in the presence of rotenone, provided that regeneration of NAD+ was affected by providing acetoacetate. 4. Hypo-osmolarity of the medium markedly stimulated the rate of degradation of glycine by mitochondria. Although hypo-osmolarity-induced stimulation of glycine degradation was accompanied by parallel changes in mitochondrial matrix volume, no measurable changes in matrix volume were observed in mitochondria stimulated either by free Ca2+ (0.5 microM) or by injection of glucagon in vivo. Furthermore, Ca2+ stimulated glycine decarboxylation in mitochondria exposed to either hyper-osmolar (410 mosmol) or hypo-osmolar (210 mosmol) conditions. Although hyper-osmolarity decreased and hypo-osmolarity increased matrix volume, stimulation of glycine degradation by Ca2+ was not associated with any further changes in matrix volume. 5. These data demonstrate that the regulation of hepatic glycine oxidation by glucagon and by free Ca2+ is largely independent of changes in mitochondrial matrix volume.

Rapid stimulation of the hepatic glycine-cleavage system in rats fed on a single high-protein meal.

Glycine catabolism was studied in isolated rat liver mitochondria by measuring the release of 14CO2 from [1-14C]glycine. Mitochondria isolated from rats fed on a high-protein (60% casein) diet for 5 days showed an enhanced ability to catabolize glycine compared with mitochondria from rats fed on a normal-protein (15% casein) diet. Glycine catabolism was also stimulated in normal protein-fed rats if they ingested a single high-protein meal for 2 h before being killed, thus illustrating the rapid response of the glycine-cleavage system to protein intake. The stimulation of glycine catabolism in rats given a high-protein diet or meal was not evident if the mitochondria were incubated in the absence of P(i) (omitting ADP had no effect on the rate). Mitochondria from high-protein- and normal-protein-fed rats did not differ in their ability to accumulate glycine, a process which occurred far too rapidly to impose a limit on the rate of flux through the glycine-cleavage system. The stimulation of glycine catabolism by high-protein feeding was not associated with a change in mitochondrial matrix volume. Furthermore, mitochondria from rats fed on a high-protein meal maintained an enhanced ability to catabolize glycine compared with those from rats fed on a normal-protein meal when incubated in hypo-osmotic solutions of very low osmolarity. When mitochondria from high-protein- or normal-protein-fed rats were maximally activated by incubation in the presence of 0.25 microM-Ca2+, the rates of glycine catabolism were high, but similar, showing that the stimulation of glycine catabolism by high-protein feeding does not involve an increase in the total capacity of the system. These findings show that hepatic glycine catabolism is stimulated rapidly by high-protein feeding, a response that we suggest is involved in the disposal of the excess glycine in the diet.

Flux through glycine cleavage system in isolated hepatocytes: effects of glucagon, cAMP, and calcium.

The hepatic glycine cleavage system (GCS) is the principal route for the metabolism of glycine in mammals. Flux through the GCS in isolated rat hepatocytes was stimulated by about 100% by glucagon (10(-7) M), forskolin (10(-4) M), and dibutyryl cAMP (10(-4) M). The stimulation of flux through the GCS by these agents was accompanied by marked elevation of cellular cAMP levels. A significant correlation was observed between increased cellular cAMP levels induced by glucagon and stimulation of flux through the GCS by glucagon. Exclusion of calcium from the incubation medium reduced the basal flux by 38%, but did not affect the degree of stimulation of flux through the GCS by glucagon. A single intraperitoneal injection of glucagon to rats prior to isolation of hepatocytes resulted in a 76% stimulation of flux through the GCS. These hepatocytes with stimulated flux through the GCS showed reduced sensitivity for further stimulation by glucagon. Half-maximal stimulation of flux through the GCS occurred at 3.8 +/- 1.1 and 8.5 +/- 1.4 nM glucagon in hepatocytes isolated from control and glucagon-injected rats, respectively. We conclude that cAMP is involved in the regulation of flux through the GCS by glucagon.

Stimulation of glycine catabolism in isolated perfused rat liver by calcium mobilizing hormones and in isolated rat liver mitochondria by submicromolar concentrations of calcium.

Glucagon stimulates flux through the glycine cleavage system (GCS) in isolated rat hepatocytes (Jois, M., Hall, B., Fewer, K., and Brosnan, J. T. (1989) J. Biol. Chem. 264, 3347-3351. In the present study, flux through GCS was measured in isolated rat liver perfused with 100 nM glucagon, 1 microM epinephrine, 1 microM norepinephrine, 10 microM phenylephrine, or 100 nM vasopressin. These hormones increased flux through GCS in perfused rat liver by 100-200% above the basal rate. The possibility that the stimulation of flux by adrenergic agonists and vasopressin is mediated by increases in cytoplasmic Ca2+ which in turn could regulate mitochondrial glycine catabolism was examined by measuring flux through GCS in isolated mitochondria in the presence of 0.04-2.88 microM free Ca2+. Flux through GCS in isolated mitochondria was exquisitely sensitive to free Ca2+ in the medium; half-maximal stimulation occurred at about 0.4 microM free Ca2+ and maximal stimulation (7-fold) was reached when the free Ca2+ in the medium was 1 microM. The Vmax (nanomoles/mg protein/min) and Km (millimolar) values for the flux through GCS in intact mitochondria were 0.67 +/- 0.16 and 20.66 +/- 4.82 in the presence of 1 mM [ethylenebis(oxyethylenenitrilo)]tetraacetic acid and 3.28 +/- 0.76 and 10.98 +/- 1.91 in presence of 0.5 microM free Ca2+, respectively. The results show that the flux through GCS is sensitive to concentrations of calcium which would be achieved in the cytoplasm of hepatocytes stimulated by calcium-mobilizing hormones.

Regulation of hepatic glycine catabolism by glucagon.

Glucagon stimulates 14CO2 production from [1-14C] glycine by isolated rat hepatocytes. Maximal stimulation (70%) of decarboxylation of glycine by hepatocytes was achieved when the concentration of glucagon in the medium reached 10 nM; half-maximal stimulation occurred at a concentration of about 2 nM. A lag period of 10 min was observed before the stimulation could be measured. Inclusion of beta-hydroxybutyrate (10 mM) or acetoacetate (10 mM) did not affect the magnitude of stimulation suggesting that the effects of glucagon were independent of mitochondrial redox state. Glucagon did not affect either the concentration or specific activity of intracellular glycine, thus excluding the possibilities that altered concentration or specific activity of intracellular glycine contributes to the observed stimulation. The stimulation of decarboxylation of glycine by glucagon was further studied by monitoring 14CO2 production from [1-14C]glycine by mitochondria isolated from rats previously injected with glucagon. Glycine decarboxylation was significantly stimulated in the mitochondria isolated from the glucagon-injected rats. We suggest that glucagon is a major regulator of hepatic glycine metabolism through the glycine cleavage enzyme system and may be responsible for the increased hepatic glycine removal observed in animals fed high-protein diets.

Effects of exogenous growth hormone on milk production and nutrient uptake by muscle and mammary tissues of dairy cows in mid-lactation.

Responses to exogenous growth hormone were measured in lactating dairy cows surgically prepared to allow measurement of nutrient exchanges across mammary and hind-limb muscle tissues. Cows were injected daily with either saline or growth hormone, at a dose of 0.1 mg/kg liveweight, over periods of 6 days. During administration of growth hormone milk yield, milk fat content and yields of milk fat protein and lactose increased. Arterial plasma concentrations of glucose and non-esterified fatty acids were increased, uptake of glucose by leg muscle tissue decreased, lactate release from leg muscle tended to increase, mammary uptake of non-esterified fatty acids increased, blood flow to leg muscle tended to increase and blood flow to mammary tissue increased during injection of growth hormone. The results show that growth hormone affects supply to and utilization of key nutrients by tissues, resulting in the supply to the mammary gland of additional precursors for milk synthesis.