Meat Science and Muscle Biology Symposium: in utero nutrition related to fetal development, postnatal performance, and meat quality of pork.

Intrauterine growth restriction (IUGR) occurs naturally in pigs and leads to low birth weight of piglets due to undernutrition caused by placental insufficiency. For 2 main reasons, low birth weight causes economic loss. First, low birth weight pigs have a greater mortality and increasing the litter size causes more low birth weight piglets within litters. Second, surviving low birth weight piglets have reduced performance (i.e., ADG, feed conversion rate, and percentage meat). To develop dietary strategies for preventing IUGR, knowledge of the biological basis of IUGR is required. Muscle fiber number, formed during myogenesis, is correlated positively with performance traits and has been shown in several studies to be reduced in low birth weight pigs. Postnatal muscle hypertrophy is due to satellite cell number per fiber at birth and their rate of proliferation as well as protein deposition (i.e., protein synthesis and degradation). Previous studies and some recent ones indicate that low birth weight littermates in mice are born with fewer satellite cells and studies on pigs show that the rate of satellite cell proliferation may vary within litters. Proteomics studies show that protein synthesis and degradation is downregulated in IUGR pigs and low birth weight pigs also produce meat with less tenderness. Alternative maternal feeding strategies to prevent IUGR have been examined. Increasing maternal global nutrition had no beneficial effect on performance and muscle growth traits in several studies. Feeding excess maternal dietary protein also did not influence muscle growth traits whereas moderately decreased maternal dietary protein may decrease muscle fiber number and performance. On the other hand, addition of L-carnitine to the maternal gestation or lactation diet may increase birth and weaning weights or the muscle fiber number, respectively, in low birth weight pig offspring. Finally, promising data have been obtained on reproductive traits in pigs after addition of functional AA, such as arginine and glutamine, to the gestational diet. Although much is known about the biological basis of IUGR, we still need to learn much more about the mode of action before maternal dietary strategies can be developed to prevent IUGR.

Postmortem genetic testing of the ryanodine receptor 2 (RYR2) gene in a cohort of sudden unexplained death cases.

The aim of this investigation was to identify pathogenic variants of the ryanodine receptor 2 (RYR2) gene in a cohort of persons aged 0-40 years who died of sudden unexpected death syndrome (SUD), including a cohort of infants who died of sudden infant death syndrome (SIDS). We genetically screened 29 of the 105 exons of the RYR2 gene associated with catecholaminergic polymorphic ventricular tachycardia (CPVT) in 74 cases of SUD without reported structural abnormalities of the heart. Cases were selected from the case database at the Institute of Forensic Medicine, and subsequent mutational screening by DNA sequencing was performed to detect variants in DNA samples extracted from blood samples of deceased persons. A total of 7 of the examined 74 cases were heterozygous for a rare sequence variant in the RYR2 gene. We identified five novel missense variants (p.Q486H, p.D1872N, p.G2367R, p.E4213D, and p.H4579Y), one synonymous variant (p.L4767L), and one previously reported missense variant (p.G4315E). Follow-up studies were possible in family members of three probands (p.Q486H, p.D1872N, and p.H4579Y), and clinical examinations were conducted in family members of two of these probands (p.Q486H and p.H4579Y). In conclusion, we identified a higher prevalence of variants in the CPVT-associated gene RYR2 than in a previously reported cohort of SIDS (9.4% vs. 1-2%). Segregation studies show that one variant (p.H4579Y) co-segregates with CPVT and is presumed to be pathogenic.

Protein expression studies of desmoplakin mutations in cardiomyopathy patients reveal different molecular disease mechanisms.

Mutations in the gene for desmoplakin (DSP) may cause arrhythmogenic right ventricular cardiomyopathy (ARVC) and Carvajal syndrome (CS). Desmoplakin is part of all desmosomes, which are abundantly expressed in both myocardial and epidermal tissue and serve as intercellular mechanical junctions. This study aimed to investigate protein expression in myocardial and epidermal tissue of ARVC and CS patients carrying DSP mutations in order to elucidate potential molecular disease mechanisms. Genetic investigations identified three ARVC patients carrying different heterozygous DSP mutations in addition to a homozygous DSP mutation in a CS patient. The protein expression of DSP in mutation carriers was evaluated in biopsies from myocardial and epidermal tissue by immunohistochemistry. Keratinocyte cultures were established from skin biopsies of mutation carriers and characterized by reverse transcriptase polymerase chain reaction, western blotting, and protein mass spectrometry. The results showed that the mutation carriers had abnormal DSP expression in both myocardial and epidermal tissue. The investigations revealed that the disease mechanisms varied accordingly to the specific types of DSP mutation identified and included haploinsufficiency, dominant-negative effects, or a combination hereof. Furthermore, the results suggest that the keratinocytes cultured from patients are a valuable and easily accessible resource to elucidate the effects of desmosomal gene mutations in humans.

Molecular autopsy in young sudden cardiac death victims with suspected cardiomyopathy.

The aim of this investigation was to identify and characterise pathogenic mutations in a sudden cardiac death (SCD) cohort suspected of cardiomyopathy in persons aged 0-40 years. The study material for the genetic screening of cardiomyopathies consisted of 41 cases and was selected from the case database at the Institute of Forensic Medicine. Mutational screening by DNA sequencing was performed to detect mutations in DNA samples from deceased persons suspected of suffering from hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and arrhythmogenic right ventricle cardiomyopathy (ARVC). A total of 9 of the examined 41 cases had a rare sequence variant in the MYBPC3, MYH7, LMNA, PKP2 or TMEM43 genes, of which 4 cases (9.8%) were presumed to be pathogenic mutations. The presumed pathogenic mutations were distributed with one case of suspected HCM and DCM (MYH7; p.R442H), one case of suspected DCM (LMNA; p.R471H), and two cases of suspected ARVC (PKP2; p.R79X and LMNA; p.R644C). The presented data adds important information on the genetic elements of SCD in the young, and calls for expert pathological evaluation and molecular autopsy in the post-mortem examination of SCD victims with structural anomalies of the heart.

Advances in research on the prenatal development of skeletal muscle in animals in relation to the quality of muscle-based food. I. Regulation of myogenesis and environmental impact.

Skeletal muscle development in vertebrates - also termed myogenesis - is a highly integrated process. Evidence to date indicates that the processes are very similar across mammals, poultry and fish, although the timings of the various steps differ considerably. Myogenesis is regulated by the myogenic regulatory factors and consists of two to three distinct phases when different fibre populations appear. The critical times when myogenesis is prone to hormonal or environmental influences depend largely on the developmental stage. One of the main mechanisms for both genetic and environmental effects on muscle fibre development is via the direct action of the growth hormone-insulin-like growth factor (GH-IGF) axis. In mammals and poultry, postnatal growth and function of muscles relate mainly to the hypertrophy of the fibres formed during myogenesis and to their fibre-type composition in terms of metabolic and contractile properties, whereas in fish hyperplasia still plays a major role. Candidate genes that are important in skeletal muscle development, for instance, encode for IGFs and IGF-binding proteins, myosin heavy chain isoforms, troponin T, myosin light chain and others have been identified. In mammals, nutritional supply in utero affects myogenesis and the GH-IGF axis may have an indirect action through the partitioning of nutrients towards the gravid uterus. Impaired myogenesis resulting in low skeletal myofibre numbers is considered one of the main reasons for negative long-term consequences of intrauterine growth retardation. Severe undernutrition in utero due to natural variation in litter or twin-bearing species or insufficient maternal nutrient supply may impair myogenesis and adversely affect carcass quality later in terms of reduced lean and increased fat deposition in the progeny. On the other hand, increases in maternal feed intake above standard requirement seem to have no beneficial effects on the growth of the progeny with myogenesis not or only slightly affected. Initial studies on low and high maternal protein feeding are published. Although there are only a few studies, first results also reveal an influence of nutrition on skeletal muscle development in fish and poultry. Finally, environmental temperature has been identified as a critical factor for growth and development of skeletal muscle in both fish and poultry.

Advances in research on the prenatal development of skeletal muscle in animals in relation to the quality of muscle-based food. II--Genetic factors related to animal performance and advances in methodology.

Selective breeding is an effective tool to improve livestock. Several selection experiments have been conducted to study direct selection responses as well as correlated responses in traits of skeletal muscle growth and function. Moreover, comparisons of domestic with wild-type species and of extreme breeds provide information on the genetic background of the skeletal muscle phenotype. Structural muscular components that differed with increasing distance in lean growth or meat quality in mammals were found to be myofibre number, myofibre size, proportions of fibre types as well as the numbers and proportions of secondary and primary fibres. Furthermore, markers of satellite cell proliferation, metabolic enzyme activities, glycogen and fat contents, the expression of myosin heavy chain isoforms, of activated AMPKα and other proteins in skeletal muscle tissue and circulating IGF1 and IGF-binding proteins have been identified to be involved in selection responses observed in pigs, cattle and/or chicken. The use of molecular methods for selective breeding of fish has only recently been adopted in aquaculture and studies of the genetic basis of growth and flesh quality traits are scarce. Some of the molecular markers of muscle structure/metabolism in livestock have also been identified in fish, but so far no studies have linked them with selection response. Genome scans have been applied to identify genomic regions exhibiting quantitative trait loci that control traits of interest, for example, muscle structure and meat quality in pigs and growth rate in chicken. As another approach, polymorphisms in candidate genes reveal the relationship between genetic variation and target traits. Thus, in large-scale studies with pigs' associations of polymorphisms in the HMGA2, CA3, EPOR, NME1 and TTN genes with traits of carcass and meat quality were detected. Other studies revealed the significance of mutations in the IGF2 and RYR1 genes for carcass lean and muscle fibre traits in pigs. Mutations in the myostatin (MSTN) gene in fish were also examined. Advances in research of the genetic and environmental control of traits related to meat quality and growth have been made by the application of holistic 'omics' techniques that studied the whole muscle-specific genome, transcriptome and proteome in relation to muscle and meat traits, the development of new methods for muscle fibre typing and the adaptation of biophysical measures to develop parameters of muscle fibre traits as well as the application of in vitro studies. Finally, future research priorities in the field are defined.

Birth weight and postnatal dietary protein level affect performance, muscle metabolism and meat quality in pigs.

Intrauterine growth restriction (IUGR), resulting in low birth body weight (LBW) occurs naturally in pigs. However, IUGR may also cause persistent changes in physiology and metabolism resulting in poorer performance, organogenesis and meat quality. As IUGR pigs have a lower daily gain from birth to slaughter they may differ in utilization of nutrients and requirements for dietary protein compared with their larger littermates. Thus, the objective in this study was to examine the interaction between birth body weight (BW) and the postnatal dietary protein level, in relation to postnatal performance, organogenesis, muscle metabolism and meat quality. The experiment was carried out with offspring from 16 purebred Danish Landrace gilts mated to Danish Landrace boars. The female and entire male pigs with LBW that survived at weaning were compared with the female and male pigs with the highest/high birth body weight (HBW) within each litter. The offspring were reared individually from weaning and were fed ad libitum a diet containing either a normal level of protein (NP) for optimal growth or an isocaloric diet containing a 30% lower protein content (LP) from 3 weeks to 150 days of age. At slaughter, we found no interactions between birth weight group and dietary protein level for any of the measured traits. The relative crown-rump length (cm/kg) at birth indicates that LBW pigs were thinner than HBW pigs. Daily gain and feed intake were reduced by 14% and 10%, respectively, while the kg feed/kg gain was slightly increased by 3% in LBW pigs compared with HBW pigs. The LP diet reduced daily gain by 27% due to reduced feed intake and increased kg feed/kg gain by 12% and 21%, respectively compared with the NP diet. LBW male pigs produced meat with a higher shear force than male HBW pigs and also LP pigs produced meat with higher shear force than NP pigs. The activity of lactate dehydrogenase in the Longissimus dorsi muscle (LD) was reduced in pigs fed the LP diet. Calpastatin was increased in LD of LBW pigs and decreased in pigs fed the NP diet. In conclusion, these results suggest a rejection of our hypothesis that low birth weight littermates have a lower requirement for dietary protein compared with heavy weight littermates. Furthermore, LBW male pigs and LP fed pigs of both genders produced less tender meat than HBW pigs or NP fed pigs, respectively.

Intraoperative hemodynamic monitoring during liver transplantation: goals and devices.

With the introduction of orthotopic liver transplantation (OLT) almost 40 years ago, changes in the cardiovascular system that manifest during the different phases of the operation combined, sometimes with massive hemorrhage in likely critically ill patients have been a challenge. Here hemodynamic monitoring of the patients during OLT is addressed with focus on maintaining the patients' central blood volume (CBV) and methods and devices that can serve that purpose are listed. It is considered that a stable CBV maintains cerebral blood flow and oxygenation and thereby the well-being of the patient, while even a small reduction in blood pressure affects cerebral blood flow and oxygenation if it reflects a reduced CBV and thereby cardiac output. In that regard it is accepted that for the patient going through OLT cardiac output (~8 L/min-1) and also venous oxygen saturation (~85%) are larger than for other categories of patients when a flow related parameter (cardiac stroke volume, cardiac output or (mixed) venous oxygen saturation) does not respond to a fluid challenge, i.e. the patient is "normovolaemic". Also the administration strategy for liver transplantation is considered with emphasis on haemostatic control resuscitation, i.e. balanced administration of red blood cells, plasma and platelets to massively bleeding patients.

Jugular venous pooling during lowering of the head affects blood pressure of the anesthetized giraffe.

How blood flow and pressure to the giraffe's brain are regulated when drinking remains debated. We measured simultaneous blood flow, pressure, and cross-sectional area in the carotid artery and jugular vein of five anesthetized and spontaneously breathing giraffes. The giraffes were suspended in the upright position so that we could lower the head. In the upright position, mean arterial pressure (MAP) was 193 +/- 11 mmHg (mean +/- SE), carotid flow was 0.7 +/- 0.2 l/min, and carotid cross-sectional area was 0.85 +/- 0.04 cm(2). Central venous pressure (CVP) was 4 +/- 2 mmHg, jugular flow was 0.7 +/- 0.2 l/min, and jugular cross-sectional area was 0.14 +/- 0.04 cm(2) (n = 4). Carotid arterial and jugular venous pressures at head level were 118 +/- 9 and -7 +/- 4 mmHg, respectively. When the head was lowered, MAP decreased to 131 +/- 13 mmHg, while carotid cross-sectional area and flow remained unchanged. Cardiac output was reduced by 30%, CVP decreased to -1 +/- 2 mmHg (P < 0.01), and jugular flow ceased as the jugular cross-sectional area increased to 3.2 +/- 0.6 cm(2) (P < 0.01), corresponding to accumulation of approximately 1.2 l of blood in the veins. When the head was raised, the jugular veins collapsed and blood was returned to the central circulation, and CVP and cardiac output were restored. The results demonstrate that in the upright-positioned, anesthetized giraffe cerebral blood flow is governed by arterial pressure without support of a siphon mechanism and that when the head is lowered, blood accumulates in the vein, affecting MAP.

Effect of thermal stress on Frank-Starling relations in humans.

The Frank-Starling 'law of the heart' is implicated in certain types of orthostatic intolerance in humans. Environmental conditions have the capacity to modulate orthostatic tolerance, where heat stress decreases and cooling increases orthostatic tolerance. The objective of this project was to test the hypothesis that heat stress augments and cooling attenuates orthostatic-induced decreases in stroke volume (SV) via altering the operating position on a Frank-Starling curve. Pulmonary artery catheters were placed in 11 subjects for measures of pulmonary capillary wedge pressure (PCWP) and SV (thermodilution derived cardiac output/heart rate). Subjects experienced lower-body negative-pressure (LBNP) of 0, 15 and 30 mmHg during normothermia, skin-surface cooling (decrease in mean skin temperature of 4.3 +/- 0.4 degrees C (mean +/- s.e.m.) via perfusing 16 degrees C water through a tubed-lined suit), and whole-body heating (increase in blood temperature of 1.0 +/- 0.1 degrees C via perfusing 46 degrees C water through the suit). SV was 123 +/- 8, 121 +/- 10, 131 +/- 7 ml prior to LBNP, during normothermia, skin-surface cooling, and whole-body heating, respectfully (P = 0.20). LBNP of 30 mmHg induced greater decreases in SV during heating (-48.7 +/- 6.7 ml) compared to normothermia (-33.2 +/- 7.4 ml) and to cooling (-10.3 +/- 2.9 ml; all P < 0.05). Relating PCWP to SV indicated that cooling values were located on the flatter portion of a Frank-Starling curve because of attenuated decreases in SV per decrease in PCWP. In contrast, heating values were located on the steeper portion of a Frank-Starling curve because of augmented decreases in SV per decrease in PCWP. These data suggest that a Frank-Starling mechanism may contribute to improvements in orthostatic tolerance during cold stress and orthostatic intolerance during heat stress.

GTPgammaS antagonizes the mastoparan-induced in vitro activity of PIP-phospholipase C from symbiotic root nodules of Phaseolus vulgaris.

Phospholipase C (PLC) has been suggested to have a role in signal perception by Nod factors (NFs) in legume root hair cells. For instance, mastoparan, a well-described agonist of heterotrimeric G protein, induces nodulin expression after NFs treatment or Rhizobium inoculation. Furthermore, it has been recently demonstrated that mastoparan also mimics calcium oscillations induced by NFs, suggesting that PLC could play a key role during the nodulation process. In this study, we elucidate a biochemical relationship between PLC and heterotrimeric G proteins during NFs signaling in legumes. In particular, the effect of NFs on in vitro PLC activity from nodule membrane fractions in the presence of guanosine 5'-[gamma-thio]triphosphate (GTPgammaS) and mastoparan was assayed. Our results indicate that for phosphatidylinositol 4,5 bisphosphate (PIP(2))-PLC, there is a specific activity of 20-27 nmol mg(-1) min(-1) in membrane fractions of nodules 18-20 days after inoculation with Rhizobium tropici. Interestingly, in the presence of 5 microM mastoparan, PIP(2)-PLC activity was almost double the basal level. In contrast, PIP(2)-PLC activity was downregulated by 1-10 microM GTPgammaS. Also, PLC activity was decreased by up to 64% in the presence of increasing concentrations of NFs (10(-8) to 10(-5) M). NFs are critical signaling molecules in rhizobia/legume symbiosis that can activate many of the plant's early responses during nodule development. Calcium spiking, kinases, PLC activity and possibly G proteins appear to be components downstream of the NFs perception pathway. Our results suggest the occurrence of a dual signaling pathway that could involve both G proteins and PLC in Phaseolus vulgaris during the development of root nodules.

Protons and how they are transported by proton pumps.

The very high mobility of protons in aqueous solutions demands special features of membrane proton transporters to sustain efficient yet regulated proton transport across biological membranes. By the use of the chemical energy of ATP, plasma-membrane-embedded ATPases extrude protons from cells of plants and fungi to generate electrochemical proton gradients. The recently published crystal structure of a plasma membrane H(+)-ATPase contributes to our knowledge about the mechanism of these essential enzymes. Taking the biochemical and structural data together, we are now able to describe the basic molecular components that allow the plasma membrane proton H(+)-ATPase to carry out proton transport against large membrane potentials. When divergent proton pumps such as the plasma membrane H(+)-ATPase, bacteriorhodopsin, and F(O)F(1) ATP synthase are compared, unifying mechanistic premises for biological proton pumps emerge. Most notably, the minimal pumping apparatus of all pumps consists of a central proton acceptor/donor, a positively charged residue to control pK(a) changes of the proton acceptor/donor, and bound water molecules to facilitate rapid proton transport along proton wires.

In vitro primary satellite cell growth and differentiation within litters of pigs.

Postnatal muscle growth is dependent on satellite cell (SC) proliferation, differentiation and fusion to increase the DNA content of existing muscle fibres and thereby the capacity to synthesize protein. The purpose of the present study was to examine the ability of isolated SCs from low, medium and high weaning weight litter mates of pigs to proliferate and differentiate, and to affect protein synthesis and degradation after fusion into myotubes. At 6 weeks of age, SCs from the lowest weight (LW), medium weight (MW) and highest weight (HW) female pigs within eight litters were isolated. Thereby, eight cultures of SCs were established for each of the three weight groups within litter, representing three groups of SCs from pigs exhibiting differences in postnatal muscle growth performance. Proliferation was estimated as the number of viable cells at different time points after seeding. SC differentiation was evaluated by measuring the activity of the muscle-specific enzyme, creatine phosphokinase, and protein synthesis and degradation were measured by incorporation and release of 3H-tyrosine, respectively. A tendency towards a difference in proliferation between SC cultures was found (P = 0.09). This was evident as the number of viable cells at day 3 was lower in cultures from LW pigs than from HW (P < 0.05) and MW (P < 0.01) pigs. Differentiation was significantly different between cultures (P < 0.05). There was a significant difference between LW and MW cultures at 72 h (P < 0.05), and a tendency towards a difference between LW and HW cultures at 45 h (P = 0.07). Protein synthesis per µg protein or per µg DNA did not differ among SC cultures from LW, MW and HW pigs. Neither did protein degradation rate differ significantly among SC cultures from LW, MW and HW pigs. Overall, the results show that SCs from LW pigs seem to proliferate and differentiate at a slower rate than SCs from MW and HW pigs. The results found in this study show no difference in the ability of SCs to affect protein synthesis or degradation between SCs from litter mates exhibiting different growth rates in vivo.

Effects of heat and cold stress on central vascular pressure relationships during orthostasis in humans.

Central venous pressure (CVP) provides information regarding right ventricular filling pressure, but is often assumed to reflect left ventricular filling pressure. It remains unknown whether this assumption is correct during thermal challenges when CVP is elevated during skin-surface cooling or reduced during whole-body heating. The primary objective of this study was to test the hypothesis that changes in CVP reflect those in left ventricular filling pressure, as expressed by pulmonary capillary wedge pressure (PCWP), during lower-body negative pressure (LBNP) while subjects are normothermic, during skin-surface cooling, and during whole-body heating. In 11 subjects, skin-surface cooling was imposed by perfusing 16 degrees C water through a water-perfused suit worn by each subject, while heat stress was imposed by perfusing 47 degrees C water through the suit sufficient to increase internal temperature 0.95 +/- 0.07 degrees C (mean +/- s.e.m.). While normothermic, CVP was 6.3 +/- 0.2 mmHg and PCWP was 9.5 +/- 0.3 mmHg. These pressures increased during skin-surface cooling (7.8 +/- 0.2 and 11.1 +/- 0.3 mmHg, respectively; P < 0.05) and decreased during whole-body heating (3.6 +/- 0.1 and 6.5 +/- 0.2 mmHg, respectively; P < 0.05). The decrease in CVP with LBNP was correlated with the reduction in PCWP during normothermia (r = 0.93), skin-surface cooling (r = 0.91), and whole-body heating (r = 0.81; all P < 0.001). When these three thermal conditions were combined, the overall r value between CVP and PCWP was 0.92. These data suggest that in the assessed thermal conditions, CVP appropriately tracks left ventricular filling pressure as indexed by PCWP. The correlation between these values provides confidence for the use of CVP in studies assessing ventricular preload during thermal and combined thermal and orthostatic perturbations.

Creatine monohydrate and glucose supplementation to slow- and fast-growing chickens changes the postmortem pH in pectoralis major.

The energy status of the chicken at slaughter has a large impact on the development of pH postmortem and thus on color and water-holding capacity (WHC). Supplementation of creatine monohydrate and glucose (CMH+GLU) may increase the creatine content in the muscles before slaughter, thereby delaying the formation of lactic acid and postponing the pH decline. The objective of this study was to examine the impact of supplementing CMH+GLU in the drinking water within the last 48 h before slaughter on the pH decline, meat color, and WHC in the pectoralis major from 2 strains of Ross chickens. Forty Ross 308 (fast-growing) female chickens and 40 Ross 1972 (slow-growing) female chickens had free access to drinking water either supplemented with CMH (15 g/ L) and glucose (50 g/L) within the last 48 h before slaughter or without supplementation. All chickens were slaughtered at 42 or 43 d of age irrespective of weight. Temperature and pH were measured at 1 and 30 min and at 1, 3, 8, and 24 h postmortem. Also, WHC measured as drip loss and color were determined postmortem. The CMH+GLU supplementation decreased pH (P < 0.05) at all time points between 1 min and 8 h postmortem in both strains, whereas at 24 h postmortem only pH in Ross 308 chickens were decreased significantly upon supplementation. Lightness was significantly increased in the meat from Ross 308 but not from Ross 1972 chickens upon supplementation. This interaction was significant (P < 0.05). The redness of the meat was decreased upon supplementation (P < 0.05), although only significantly in Ross 1972. The pH was lower for Ross 1972 chickens at the early time points (P < 0.01) and also a higher drip loss (P < 0.05), lightness (P < 0.01), and redness (P < 0.001) were observed. Thus, there seems to be no beneficial effect of CMH+GLU supplementation on chicken meat quality on the basis of results from this experiment.

Serum from heifer calves treated with bovine growth hormone affects the rate of proliferation of C2C12 myogenic cells dependent on the plane of nutrition: the role of insulin-like growth factor-I and IGF-binding proteins-2 and -3.

The present in vitro experiments were carried out in order to study whether variations in the bovine growth hormone (bGH)/insulin-like growth factor (IGF)-I axis induced by plane of nutrition and bGH treatment of heifer calves caused variations in serum-induced proliferation of C2C12 myoblasts. Serum was obtained from two groups each of six heifer calves (195 +/- 8 kg) before (d -1) and after treatment with 15 mg/day of bGH for 6 days (d 6) fed either a low (GHL) or a high plane (GHH) of nutrition. Preceding the experiment all 12 heifer calves were fed at the low plane of nutrition. At d 6, serum concentrations of insulin and IGF-I were increased while that of IGF-binding proteins (IGFBP)-2 was decreased in GHH, but unchanged in GHL calves. Serum-induced proliferation of C2C12 myoblasts, was elevated at d 6 by GHH treatment. Especially human IGFBP-3 but also bovine IGFBP-2 added to cell cultures inhibited the rate of proliferation of C2C12 myoblasts stimulated by human IGF-I. The present results showed that GH treatment causes changes in the GH/IGF axis, which leads to changes in serum-induced growth of C2C12 muscle cells dependent on the plane of nutrition that mimic in vivo effects of GH treatment, which indicate an endocrine contribution of the IGF system. However, drawbacks of this suggestion are discussed.

Intracellular pH homeostasis plays a role in the NaCl tolerance of Debaryomyces hansenii strains.

The effects of NaCl stress on cell area and intracellular pH (pHi) of individual cells of two Debaryomyces hansenii strains were investigated. Our results show that one of the strains was more NaCl tolerant than the other, as determined by the rate of growth initiation. Whereas NaCl stress caused similar cell shrinkages (30-35%), it caused different pHi changes of the two D. hansenii strains; i.e., in the more NaCl-tolerant strain, pHi homeostasis was maintained, whereas in the less NaCl-tolerant strain, intracellular acidification occurred. Thus, cell shrinkage could not explain the different intracellular acidifications in the two strains. Instead, we introduce the concept of yeasts having an intracellular pKa (pK(a,i)) value, since permeabilized D. hansenii cells had a very high buffer capacity at a certain pH. Our results demonstrate that the more NaCl-tolerant strain was better able to maintain its pK(a,i) close to its pHi homeostasis level during NaCl stress. In turn, these findings indicate that the closer a D. hansenii strain can keep its pK(a,i) to its pHi homeostasis level, the better it may manage NaCl stress. Furthermore, our results suggest that the NaCl-induced effects on pHi were mainly due to hyperosmotic stress and not ionic stress.

The estimated accuracy of the EU reference dissection method for pig carcass classification.

This experiment was designed to describe the accuracy of the EU-reference dissection method, and to describe the types of factors influencing the accuracy and assess their size. The experiment was conducted in four different European countries at two abattoirs within each country. A total of 128 carcasses was selected according to carcass weight, fat class and sex, and 8 butchers from different countries dissected the carcasses. Due to the experimental design of the experiment a variation in pig type was found between countries. The accuracy was expressed by the repeatability and reproducibility standard deviation, which were found to be 0.87 and 1.10, respectively, and by the reliability, found to be 0.87. This indicates a high accuracy, although a significant effect was found on the estimation of lean meat percentage (LMP) of butcher, and also that jointing of the carcass was of overall importance to the accuracy of the EU-reference dissection method.

Within-litter variation in muscle fiber characteristics, pig performance, and meat quality traits.

The objective of this study was to examine the intralitter variation in postnatal growth performance, meat quality, and muscle fiber characteristics when littermates were categorized by carcass weight. Thirty-nine litters were weaned at 4 wk of age and had free access to feed from 2 wk of age until slaughter. They were slaughtered by litter at an average BW of 104 +/- 14 kg, and six pigs per litter were selected for analysis: the heaviest- (HW), middle- (MW), and lightest-weight (LW) pig of each sex. Categorizing littermates in LW, MW, and HW pigs at the same age reflected the differences in postnatal growth rate within a litter; thus ADG, muscle mass, and muscle deposition rate differed across pig weight groups (P < 0.001). Also, the total DNA content was different among pig weight groups (P < 0.001) and reflected differences in muscle growth rate. The difference in muscle growth rate between LW and MW pigs could be explained by a larger (P < 0.05) mean fiber area (MFA) in MW pigs, whereas the number of muscle fibers was similar. Growth rate differences between MW and HW pigs could in part be explained by a higher number (P < 0.01) of equal-sized muscle fibers in HW pigs. The difference in MFA was due to a higher estimated DNA and RNA content per muscle fiber in MW and HW compared with LW pigs (P < 0.05). Pigment content was higher in MW and HW compared with LW pigs (P < 0.01), but no other measured meat quality traits were significantly different across pig weight groups. These results indicate that both the number and the growth rate of muscle fibers contribute to intralitter variation in postnatal growth performance.

Effect of fitness on arm vascular and metabolic responses to upper body exercise.

We investigated arm perfusion and metabolism during upper body exercise. Eight average, fit subjects and seven rowers, mean +/- SE maximal oxygen uptake (VO2 max) 157 +/- 7 and 223 +/- 14 ml O2. kg(-0.73).min(-1), respectively, performed incremental arm cranking to exhaustion. Arm blood flow (ABF) was measured with thermodilution and arm muscle mass was estimated by dual-energy X-ray absorptiometry. During maximal arm cranking, pulmonary VO2 was approximately 45% higher in the rowers compared with the untrained subjects and peak ABF was 6.44 +/- 0.40 and 4.55 +/- 0.26 l/min, respectively (P < 0.05). The arm muscle mass for the rowers and the untrained subjects was 3.5 +/- 0.4 and 3.3 +/- 0.1 kg, i.e., arm perfusion was 1.9 +/- 0.2 and 1.4 +/- 0.1 l blood.kg(-1).min(-1), respectively (P < 0.05). The arteriovenous O2 difference was 156 +/- 7 and 120 +/- 8 ml/l, respectively, and arm VO2 was 0.98 +/- 0.08 and 0.60 +/- 0.04 l/min corresponding with 281 +/- 22 and 181 +/- 12 ml/kg, while arm O(2) diffusional conductance was 49.9 +/- 4.3 and 18.6 +/- 3.2 ml.min(-1).mmHg(-1), respectively (P < 0.05). Also, lactate release in the rowers was almost three times higher than in the untrained subjects (26.4 +/- 1.1 vs. 9.5 +/- 0.4 mmol/min, P < 0.05). The energy requirement of an approximately 50% larger arm work capacity after long-term arm endurance training is covered by an approximately 60% increase in aerobic metabolism and an almost tripling of the anaerobic capacity.