Requirement of the inositol trisphosphate receptor for activation of store-operated Ca2+ channels.

The coupling mechanism between endoplasmic reticulum (ER) calcium ion (Ca2+) stores and plasma membrane (PM) store-operated channels (SOCs) is crucial to Ca2+ signaling but has eluded detection. SOCs may be functionally related to the TRP family of receptor-operated channels. Direct comparison of endogenous SOCs with stably expressed TRP3 channels in human embryonic kidney (HEK293) cells revealed that TRP3 channels differ in being store independent. However, condensed cortical F-actin prevented activation of both SOC and TRP3 channels, which suggests that ER-PM interactions underlie coupling of both channels. A cell-permeant inhibitor of inositol trisphosphate receptor (InsP3R) function, 2-aminoethoxydiphenyl borate, prevented both receptor-induced TRP3 activation and store-induced SOC activation. It is concluded that InsP3Rs mediate both SOC and TRP channel opening and that the InsP3R is essential for maintaining coupling between store emptying and physiological activation of SOCs.

TRPC channels: integrators of multiple cellular signals.

TRPC channels are ubiquitously expressed among cell types and mediate signals in response to phospholipase C (PLC)-coupled receptors. TRPC channels function as integrators of multiple signals resulting from receptor-induced PLC activation, which catalyzes the breakdown of phosphatidylinositol 4,5-bisphosphate (PIP2) to produce inositol 1,4,5-trisphosphate (InsP3) and diacylglycerol (DAG). InsP3 depletes Ca2+ stores and TRPC3 channels can be activated by store-depletion. InsP3 also activates the InsP3 receptor, which may undergo direct interactions with the TRPC3 channel, perhaps mediating store-dependence. The other PLC product, DAG, has a direct non-PKC-dependent activating role on TRPC3 channels likely by direct binding. DAG also has profound effects on the TRPC3 channel through PKC. Thus PKC is a powerful inhibitor of most TRPC channels and DAG is a dual regulator of the TRPC3 channel. PLC-mediated DAG results in rapid channel opening followed later by a slower DAG-induced PKC-mediated deactivation of the channel. The decreased level of PIP2 from PLC activation also has an important modifying action on TRPC3 channels. Thus, the TRPC3 channel and PLCgamma form an intermolecular PH domain that has high specificity for binding PIP2. This interaction allows the channel to be retained within the plasma membrane, a further operational control factor for TRPC3. As nonselective cation channels, TRPC channel opening results in the entry of both Na+ and Ca2+ ions. Thus, while they may mediate Ca2+ entry signals, TRPC channels are also powerful modifiers of membrane potential.

The involvement of dopamine D2 receptors, but not D3 or D4 receptors, in the rewarding effect of brain stimulation in the rat.

To identify the subtype of dopamine receptors critically involved in the rewarding effect of brain stimulation, four dopamine antagonists were intracranially injected in 25 rats. The importance of dopamine D1 receptors had been demonstrated previously by using SCH 23390, a highly selective D1 antagonist. Rats were implanted with electrodes into the medial forebrain bundle and cannulae into either one of the following structures: the nucleus accumbens, the vicinity of the islands of Calleja, or the ventral tegmental area, all ipsilateral to the electrodes. The animals were trained to press a bar for electrical stimulation, and the frequency-response functions were plotted before and after injection of each dopamine antagonist through the cannulae. Raclopride and haloperidol, which have high affinities for D2 receptors, reduced the rewarding effect after injection into any one of the three cannula sites. Neither (+)-UH232, a selective D3 antagonist, nor clozapine, a D4 antagonist, influenced the rewarding effect. The results suggest that dopamine D2, but not D3 or D4, receptors are critically involved in producing the rewarding effect of brain stimulation.

Interpreting the sounds of swallowing: fluid flow through the cricopharyngeus.

The sounds of swallowing in normal subjects were recorded by means of a miniature accelerometer on the throat, simultaneously with videofluoroscopy of a modified barium swallow. Consistent correspondence was found between a rapid change in the acoustic spectrum of the accelerometer signal (the appearance of a region of energy prominence above 1,000 Hz) and bolus flow through the cricopharyngeus.

Effect of sex grouping during growth on 5α-androstenone development in boars at three commercial slaughter weights.

Groups of boars and gilts were grown in either single-sex or mixed groups to slaughter weights of 81, 93 or 110 kg liveweight to examine the effects of sex grouping on growth performance, animal behaviour and the development of androstenone-taint in the males. Results confirmed the well known growth advantages of entire males and showed that no husbandry problems of any significance were incurred with the boars and gilts raised together, particularly in those groups slaughtered before reaching 100 kg liveweight. In pigs taken to heavier weights, boars were successfully reared with gilts without incurring management problems, although growth performance was slightly poorer for the boar/gilt groups compared with mixed castrates and gilts, and some of the boars had high concentrations of androstenone in the fat. Thus, for pigs intended for slaughter at heavy commercial weight, the evidence suggests that split-sex rearing (and therefore feeding) should be practised. No useful correlations of androstenone concentration in fat were found with thickness of backfat, age, carcass weight or liveweight at slaughter.

Anabolic agents and meat quality: A review.

This review considers the results of more than sixty studies on the possible effects of anabolic agents on the meat quality parameters of the three main red meat species and poultry. The information is grouped into three main sections: carcass composition, muscle quality and eating quality. Each section is further divided by animal species, with consideration given to differences due to sex or age. Anabolic agents appear to have some effect on the carcass composition of animals; depending upon the type used, they can cause an increase in the ratio of muscle to fat in female and castrate animals, or a decrease in this ratio in entire males. Such differences are usually reflected in related changes in the chemical composition of the meat. Few consistent effects, however, have been reported in the eating quality of the cooked meat in terms of texture, flavour, juiciness or cooking loss, indicating that the basic eating quality attributes important to the consumer are largely unaffected by hormone treatment.

Double-antibody ELISA for detection of trace amounts of pig meat in raw meat mixtures.

A modification of double-antibody sandwich ELISA (enzyme-linked immunosorbent assay) has been applied successfully to the problem of the detection of very low amounts of pig meat (1-3%) in beef and manufactured beef products made with rusk and other additives. The assay uses a monospec fic antiserum bound to the solid plastic support to sequester the porcine serum albumin (PSA) from amongst the many proteins co-extracted from the complex sample extracts. Further immuno-recognition was made with a second antibody, also specific for PSA, which was detected by a conjugated enzyme anti-IgG that interacted only with the second anti-PSA antibodies. Subsequent enzymic conversion of substrate gave clear visual differences between beef and beef containing 0·5% of pig meat and beef products with 1% of the lean replaced by lean pork compared with reference samples.

Collagen content of meat carcasses of known history.

Thirteen beef carcasses and twenty-seven pig carcasses were analysed for collagen content. The beef carcasses were drawn from four breeds and four levels of fatness. They were dissected into ten joints: from the forequarter; shin, brisket, Jacob's ladder, clod, sticking, fore-rib, chuck: from the hindquarter; leg, thin flank and other joints. Samples of each joint were analysed for fat, moisture and collagen. Samples of the total forequarter and hindquarter meat were also analysed. The pig carcasses were drawn from three weight groups and three levels of fatness. Samples from each carcass were analysed for fat, moisture and collagen. Six selected pigs were dissected into five joints: hand, collar, back, streak and ham. Samples of each joint were analysed as described above. Results from beef carcasses showed that collagen in the forequarter (3·2% wet fat-free) was significantly higher than in the hindquarter (2·7% wet fat-free). Within the forequarter collagen in the shin (4·8% wet fat-free) was significantly higher than in the other six joints. Within the hindquarter percentage collagen was significantly highest in the leg (4·2% wet fat-free). There were no significant breed differences. Results from pig carcasses showed an overall mean value for collagen of 2·3% wet fat-free. Percentage collagen was significantly highest in the hand (2·9% wet fat-free).

Identification of the species origin of fresh meat using an enzyme-linked immunosorbent assay procedure.

A modification of indirect enzyme-linked immunosorbent assay (ELISA) has been successfully applied to the detection of horse meat and beef. This technically simple assay requiring species specific antibody, conjugated enzyme anti-IgG and a polystyrene protein-binding solid phase, can be adapted for the identification of meat species in circumstances where laboratory facilities are minimal.

Characterisation and development of 'the shield' in male pigs.

A project was undertaken to characterise boar shield, study its development and determine whether it presents carcass quality problems in young boars used for meat production. In two old boars (>2·5 years) 'backfat' from the scapular region consisted mainly of a dense white tissue with a high collagen content (>20% of fresh weight) and a low lipid content (<10%) compared with normal backfat. Histologically and chemically it resembled the dermis of skin. In a development study in boars and castrates from the Large White and Pietrain breeds, collagen concentration in scapular backfat increased between 91 and 118 kg liveweight in all pigs but the increase was greater in boars than castrates and especially marked in Pietrain boars in which the mean collagen concentration was 18% at 118 kg. This was probably because of the older age of Pietrains since there was a high correlation between age and collagen concentration (r = 0·93). The results suggest that, at 'heavy hog' weights, boar shield could present a carcass quality problem in slow-growing breeds such as the Pietrain.

Investigation of methods to detect mechanically recovered meat in meat products - I: Chemical composition.

The proximate composition (fat, moisture, nitrogen, ash and collagen) and the calcium, iron and total purine contents of samples of mechanically recovered meat (MRM) derived from beef, lamb, pork, chicken and turkey were analysed. The data obtained illustrate the variability in the composition of mechanically recovered meats derived from different meat species. The effect of including a high proportion of bones containing marrow in the starting material, the effect of recovery machine type (Yieldmaster and Protecon) and the effect of employing different operating conditions, were investigated. MRM produced using the Yieldmaster machine was generally found to contain higher concentrations of ash and calcium than that produced using the Protecon machine. Although operating conditions appeared to have little effect on the composition of mechanically recovered chicken meat, some differences were identified in mechanically recovered turkey and pork produced under different conditions. Comparison of the composition of MRM with that of meat removed manually, from close to the bone, from similar source materials highlighted a number of differences between the.

Monoclonal antibody sandwich ELISA for the potential detection of chicken meat in mixtures of raw beef and pork.

A sandwich ELISA (enzyme-linked immunosorbent assay) has been developed successfully for the detection of defined amounts of chicken meat (1-100%) in beef and pork meat mixtures. The assay uses a monoclonal antibody (BC9) specific to a chicken muscle soluble protein to capture this protein from complex meat mixtures. Further immunorecognition of the captured protein was attained with rabbit polyclonal antibodies against chicken muscle proteins (anti-CHSP). A commercial goat anti-rabbit immunoglobulin conjugated to peroxidase was used to detect the anti-CHSP antibodies bound to the chicken protein. Subsequent enzymic conversion of substrate gave clear optical density differences when assaying mixtures of beef and pork meats containing variable amounts of chicken meat.

Responses of two genotypes of chicken to the diets and stocking densities typical of UK and 'Label Rouge' production systems: I. Performance, behaviour and carcass composition.

'Label Rouge' (LR) chickens are reputed to possess improved sensory characteristics compared with birds reared under intensive conditions. The effects on body weight, food utilisation, behaviour and carcass composition, of genotype (Ross I vs ISA '657'), diet (conventional UK broiler vs LR) and stocking density (17.0 birds m(-2),vs 4.25 birds m(-2)) were evaluated in a 2 × 2 × 2 experiment. ISA birds were grown to 83 days, and compared with Ross birds grown to 48 days; additionally ad libitum and control-fed Ross birds were grown to 83 days. Performance and behaviour parameters were assessed empirically. The effects on carcass composition were evaluated using standardised carcass dissection techniques and analysed by analysis of variance. ISA birds grown under LR conditions to 83 days had similar body weights to Ross birds grown under UK broiler conditions to 48 days, but LR birds consumed more food, and converted food into meat less efficiently. LR birds had no mortality, whilst UK broiler mortality was 11.3%. Under similar conditions, Ross birds had a faster body weight gain, a larger food intake, but more efficient food conversion ratio and higher incidence of mortality. Birds stocked 17.0 m(-2) had lower body weights, consumed less food and, when fed UK diets, converted food less efficiently than birds stocked 4.25 m(-2). Both genotypes had a faster growth rate on UK diets, similar food intakes, and, as a result, better food conversion than birds given LR diets. LR and UK broiler birds had similar carcass component weights, breast meat yields, and total meat yield, but LR birds had less meat on the frame, larger drumsticks and more meat on the wings. Under similar conditions, ISA birds had a larger percentage of wing and total bone, but a smaller percentage of breast meat and total meat yields. When Ross birds had controlled growth, total meat, bone and skin yields were similar to those of ISA birds. Birds stocked 4.25 m(-2) had more breast meat and larger frames than, but similar meat, bone and skin yields to, birds stocked 17.0 m(-2). Most carcass components were heavier in birds fed UK broiler diets, but, on a percentage basis, these birds had larger thighs, but smaller drumsticks.

Production and characterization of monoclonal antibodies specific to chicken muscle soluble proteins.

Three stable hybridoma cell lines (AH4, BC9 and CF2) have been produced which secrete monoclonal antibodies specific for chicken and turkey muscle proteins. Partial characterization by ELISA and SDS-PAGE immunoblotting indicated that the antibodies failed to cross-react with similar extracts of pork, beef, lamb, horse or rabbit. One of the cell lines (AH4) secreted a monoclonal antibody that was also capable of distinguishing between chicken and turkey by indirect ELISA.

Responses of two genotypes of chicken to the diets and stocking densities of conventional UK and Label Rouge production systems-II. Sensory attributes.

French Label Rouge quality chickens are reputed to possess improved sensory characteristics compared with birds reared under intensive conditions. The effects of genotype, diet, stocking density and age on eating quality were evaluated in a 2 × 2 × 2 experiment. The results suggest that genotype, diet, age and, to a lesser extent, stocking density can influence eating quality. The most pronounced sensory differences between the two genotypes were in the appearance and texture of the cooked meat. In particular, scores for toughness were higher for breast meat from Ross than ISA birds, though the opposite effect was observed for the thigh meat. Diet and age also affected texture, with the breast meat from chickens on the Label Rouge diet, or from older birds, having lower scores for toughness. Effects on odour and flavour were generally small and subject to genotype × diet interactions. The odour and flavour intensity of breast meat increased with age, while the odour intensity of thigh meat was higher in birds reared at low stocking density.

Conditioning and post-hospital generalization of nondelusional responses in a chronic psychotic patient.

An operant conditioning approach was successful in getting a chronic psychotic patient to give factual answers to direct questions that had previously elicited only delusional responses. Multiple baseline and reversal controls established that the changes were due to the experimental procedure. The subject was a female patient classified as paranoid schizophrenic who had persisted in giving bizarre responses to direct questions regarding her identity, age, and personal history during 26 yr of hospitalization. She was discharged after factual answers to these questions had been obtained, but operant conditioning trials were continued in the community to promote generalization. Two follow-up interviews were conducted 36 and 52 days after discharge to evaluate generalization. No generalization was found in the first interview, but the second gave evidence of some generalization.

Exploring phospholipase C-coupled Ca(2+) signalling networks using Boolean modelling.

In this study, the authors explored the utility of a descriptive and predictive bionetwork model for phospholipase C-coupled calcium signalling pathways, built with non-kinetic experimental information. Boolean models generated from these data yield oscillatory activity patterns for both the endoplasmic reticulum resident inositol-1,4,5-trisphosphate receptor (IP(3)R) and the plasma-membrane resident canonical transient receptor potential channel 3 (TRPC3). These results are specific as randomisation of the Boolean operators ablates oscillatory pattern formation. Furthermore, knock-out simulations of the IP(3)R, TRPC3 and multiple other proteins recapitulate experimentally derived results. The potential of this approach can be observed by its ability to predict previously undescribed cellular phenotypes using in vitro experimental data. Indeed, our cellular analysis of the developmental and calcium-regulatory protein, DANGER1a, confirms the counter-intuitive predictions from our Boolean models in two highly relevant cellular models. Based on these results, the authors theorise that with sufficient legacy knowledge and/or computational biology predictions, Boolean networks can provide a robust method for predictive modelling of any biological system. [Includes supplementary material].