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The calcium channel γ6subunit modulates low voltage-activated (LVA) calcium current in both human embryonic kidney (HEK) cells and cardiomyocytes, although the mechanism of modulation is unknown. We recently showed that γ6contains a critical GxxxA motif in the first transmembrane domain (TM1) that is essential for its inhibition of the Cav3.1 (LVA) calcium current. In this study, we tested the hypothesis that an eight-amino acid peptide that contains the GxxxA motif from γ6TM1 can act as a novel pharmacological inhibitor of the Cav3.1 calcium current by performing whole-cell electrophysiology. Our results demonstrate that the peptide inhibits Cav3.1 current by dynamically binding and dissociating from the Cav3.1 channel in a concentration-dependent but largely voltage-independent manner. By selectively substituting residues within the peptide, we show that both the GxxxA framework and surrounding aliphatic side-chains contribute to the presumably interhelical interactions between γ6TM1 and the Cav3.1 channel. The fast kinetics of the interaction supports the view that γ6acts as an endogenous LVA channel antagonist within the plasma membrane, suggesting a mechanism other than regulation of surface expression or membrane trafficking of the poreforming subunit of the channel. We also demonstrate that the peptide has different affinities for Cav3.1 and Cav1.2 calcium currents, which is consistent with the selective effect of γ6on LVA and high voltage-activated calcium currents in vivo.

The calcium channel γ6subunit modulates low voltage-activated (LVA) calcium current in both human embryonic kidney (HEK) cells and cardiomyocytes, although the mechanism of modulation is unknown. We recently showed that γ6contains a critical GxxxA motif in the first transmembrane domain (TM1) that is essential for its inhibition of the Cav3.1 (LVA) calcium current. In this study, we tested the hypothesis that an eight-amino acid peptide that contains the GxxxA motif from γ6TM1 can act as a novel pharmacological inhibitor of the Cav3.1 calcium current by performing whole-cell electrophysiology. Our results demonstrate that the peptide inhibits Cav3.1 current by dynamically binding and dissociating from the Cav3.1 channel in a concentration-dependent but largely voltage-independent manner. By selectively substituting residues within the peptide, we show that both the GxxxA framework and surrounding aliphatic side-chains contribute to the presumably interhelical interactions between γ6TM1 and the Cav3.1 channel. The fast kinetics of the interaction supports the view that γ6acts as an endogenous LVA channel antagonist within the plasma membrane, suggesting a mechanism other than regulation of surface expression or membrane trafficking of the poreforming subunit of the channel. We also demonstrate that the peptide has different affinities for Cav3.1 and Cav1.2 calcium currents, which is consistent with the selective effect of γ6on LVA and high voltage-activated calcium currents in vivo.

Post-starburst (E+A or k+a) spectra, characterized by their exceptionally strong Balmer lines in absorption and the lack of emission lines, belong to galaxies in which the star formation (SF) activity ended abruptly sometime during the past Gyr. We perform a spectral analysis of galaxies in clusters, groups, poor groups, and the field at z = 0.4-0.8 based on the ESO Distant Cluster Survey. We find that the incidence of k+a galaxies at these redshifts depends strongly on environment. K+a's reside preferentially in clusters and, unexpectedly, in a subset of the s = 200-400 km s-1 groups, those that have a low fraction of O II emitters. In these environments, 20%-30% of the star-forming galaxies have had their SF activity recently truncated. In contrast, there are proportionally fewer k+a galaxies in the field, the poor groups, and groups with a high O II fraction. An important result is that the incidence of k+a galaxies correlates with the cluster velocity dispersion: more massive clusters have higher proportions of k+a's. Spectra of dusty starburst candidates, with strong Balmer absorption and emission lines, present a very different environmental dependence from k+a's. They are numerous in all environments at z = 0.4-0.8, but they are especially numerous in all types of groups, favoring the hypothesis of triggering by a merger. We present the morphological type, stellar mass, luminosity, mass-to-light ratio, local galaxy density, and clustercentric distance distributions of galaxies of different spectral types. These properties are consistent with previous suggestions that cluster k+a galaxies are observed in a transition phase, at the moment they are rather massive S0 and Sa galaxies, evolving from star-forming, recently infallen later types to passively evolving cluster early-type galaxies. The correlation between k+a fraction and cluster velocity dispersion supports the hypothesis that k+a galaxies in clusters originate from processes related to the intracluster medium, while several possibilities are discussed for the origin of the puzzling k+a frequency in low-O II groups.

We investigate how the [O II] properties and the morphologies of galaxies in clusters and groups at z = 0.4-0.8 depend on projected local galaxy density, and compare with the field at similar redshifts and clusters at low z. In both nearby and distant clusters, higher density regions contain proportionally fewer star-forming galaxies, and the average [O II] equivalent width of star-forming galaxies is independent of local density. However, in distant clusters the average current star formation rate (SFR) in star-forming galaxies seems to peak at densities ~15-40 galaxies Mpc[?]2. At odds with low-z results, at high z the relation between star-forming fraction and local density varies from high- to low-mass clusters. Overall, our results suggest that at high z the current star formation (SF) activity in star-forming galaxies does not depend strongly on global or local environment, though the possible SFR peak seems at odds with this conclusion. We find that the cluster SFR normalized by cluster mass anticorrelates with mass and correlates with the star-forming fraction. These trends can be understood given (1) that the average star-forming galaxy forms about 1 M yr[?]1 (uncorrected for dust) in all clusters; (2) that the total number of galaxies scales with cluster mass; and (3) the dependence of star-forming fraction on cluster mass. We present the morphology-density (MD) relation for our z = 0.4 [?] 0.8 clusters, and uncover that the decline of the spiral fraction with density is entirely driven by galaxies of type Sc or later. For galaxies of a given Hubble type, we see no evidence that SF properties depend on local environment. In contrast with recent findings at low z, in our distant clusters the SF-density relation and the MD relation are equivalent, suggesting that neither of the two is more fundamental than the other.

We study how the proportion of star-forming galaxies evolves between z = 0.8 and 0 as a function of galaxy environment, using the O II line in emission as a signature of ongoing star formation. Our high-z data set comprises 16 clusters, 10 groups, and another 250 galaxies in poorer groups and the field at z = 0.4-0.8 from the ESO Distant Cluster Survey, plus another 9 massive clusters at similar redshifts. As a local comparison, we use galaxy systems selected from the Sloan Digital Sky Survey (SDSS) at 0.04 < z < 0.08. At high z most systems follow a broad anticorrelation between the fraction of star-forming galaxies and the system velocity dispersion. At face value, this suggests that at z = 0.4-0.8 the mass of the system largely determines the proportion of galaxies with ongoing star formation. At these redshifts the strength of star formation (as measured by the O II equivalent width) in star-forming galaxies is also found to vary systematically with environment. SDSS clusters have much lower fractions of star-forming galaxies than clusters at z = 0.4-0.8 and, in contrast with the distant clusters, show a plateau for velocity dispersions [?]550 km s-1, where the fraction of galaxies with O II emission does not vary systematically with velocity dispersion. We quantify the evolution of the proportion of star-forming galaxies as a function of the system velocity dispersion and find that it is strongest in intermediate-mass systems (s ~ 500-600 km s-1 at z = 0). To understand the origin of the observed trends, we use the Press-Schechter formalism and the Millennium Simulation and show that galaxy star formation histories may be closely related to the growth history of clusters and groups. If the scenario we propose is roughly correct, the link between galaxy properties and environment is extremely simple to predict purely from a knowledge of the growth of dark matter structures.

The γ subunits of voltage-dependent calcium channels influence calcium current properties and may be involved in other physiological functions. Five distinct γ subunits have been described from human and/or mouse. The first identified member of this group of proteins, γ1, is a component of the L-type calcium channel expressed in skeletal muscle. A second member, γ2, identified from the stargazer mouse regulates the targeting of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors to the postsynaptic membrane. We report here the identification of three novel γ subunits from rat and mouse as well as the unidentified rat, mouse and human orthologs of the previously described subunits. Phylogenetic analysis of the 24 mammalian γ subunits suggests the following relationship ((((γ2, γ3), (γ4, γ8)), (γ5, γ7)), (γ1, γ6)) that indicates that they evolved from a common ancestral γ subunit via gene duplication. Our analysis reveals that the novel γ subunit γ6most closely resembles γ1and shares with it the lack of a PSD-95/DLG/ZO-1 (PDZ)-binding motif that is characteristic of most other γ subunits. Rat γ subunit mRNAs are expressed in multiple tissues including brain, heart, lung, and testis. The expression of γ1mRNA and the long isoform of γ6mRNA is most robust in skeletal muscle, while γ6is also highly expressed in cardiac muscle. Based on our analysis of the molecular evolution, primary structure, and tissue distribution of the γ subunits, we propose that γ1and γ6may share common physiological functions distinct from the other homologous γ subunits.

A novel optical measurement technique for the in situdetermination of surface temperature is presented. The technique employs modulation of the object temperature by an energy source of high intensity, such as a laser. By modulation of the temperature at the point from which the emitted spectrum of electro-magnetic radiation is being monitored, routine calculations involving the observed modulated component of the radiation spectrum will determine the temperature and, for some conditions, emissivity. The region to be measured is thus defined by the intersection of the laser and the beam which enters the collection optics of the Fourier transform Infrared spectrometer. Analysis of the modulated radiation results in a temperature determination which is independent of material emissivity, surrounding radiation sources, and instrument calibration for optical path.

The ability of myofilament space Ca2+ to modulate Ca2+ release from the sarcoplasmic reticulum (SR) of skeletal muscle was investigated. Single fibers of the frog Rana pipiens belindieri were manually skinned (sarcolemma removed). Following a standard load and pre-incubation in varying myoplasmic Ca2+ concentrations, SR Ca2+ release was initiated by caffeine. Ca2+ release rates were calculated from the changes in absorbance of a Ca2+ sensitive dye, antipyrylazo III. An apparent dissociation constant (Kd) for dye-Ca2+ binding of 8000 µM2 was determined by comparing the buffering action of the dye with that of ethylenebis(oxonitrilo)tetraacetate (EGTA) using the contractile proteins of the skinned fiber as a measure of free Ca2+. This value for Kd was used in the calculation of Ca2+ release rates. As the myoplasmic space Ca2+ was increased from pCa 7.4, Ca2+ release rates declined sharply such that at pCa 6.9 the calculated release rate was 72±3% (mean ± SEM) of control (pCa 8.4). Further increases in myoplasmic Ca2+ from pCa 6.9 to pCa 6.1 did not result in a further decline in release rate. The effect of a decreased driving force on Ca2+ ions was investigated to determine whether it could account for the change in release rates observed. At pCa 6.9, where the greatest degree of inactivation occurred, the measured effects of a change in driving force could account for at most 40% of the observed inactivation. Varying concentrations of Ba2+ and Sr2+ in the myofilament space had no inactivating effect on the SR Ca2+ release rates. The ability of myofilament Ca2+ to inhibit SR Ca2+ release at concentrations normally encountered during muscle activation suggests a role for released Ca2+ as a modulator of the SR Ca2+ channel.

Abstract: We have determined the effects of the perchlorate ion on the contracture of skinned (sarcolemma removed) skeletal muscle fibres, stimulated either by ionic substitution or caffeine. Calcium release was monitored in single cells by measuring the peak height of tension transients. Perchlorate significantly sensitizes fibres to activation by ionic substitution, a manipulation that is thought to trigger calcium release via the normal physiological pathway. Adding 0.8 mM perchlorate to the solutions shifted the curve relating the magnitude of ionic substitution to the level of activation leftward, such that smaller stimuli were needed to produce a contracture of a given height. Perchlorate could also trigger a contracture directly. Exposing fibres to 1.0 mM perchlorate caused contractures averaging 60% of bracketing controls. In contrast to contractures stimulated by ionic substitution, those triggered by caffeine were unaffected by perchlorate. Since caffeine is thought to act directly on the sarcoplasmic reticulum to cause calcium release, these results suggest that perchlorate enhances activation in skinned fibres by interacting with transverse tubular membranes.

In this paper we report on a new method for the on-line chemical characterization of gas-suspended particulate and liquid droplet streams. The method is a combination of emission and transmission (E/T) spectroscopy performed using a Fourier transform infrared (FT-IR) spectrometer and a cell which allows analysis of room-temperature particulates surrounded by hot walls. The method was based on the discovery that the spectrum of radiation coming from such particles contained structure corresponding to the infrared absorption spectrum of the particulates. It was determined that the observed energy was wall radiation which reaches the detector after refraction by, and transmission through the particles. The shape of the observed spectrum relative to that of the wall spectrum is reduced at the absorption bands of the particulates. The general concepts of the E/T method were validated by samples with sizes varying from a few to several hundred microns with varying optical properties. For solids, excellent results were achieved for composition measurements. For a sample of known particle size, quantitative absorbance spectra were obtained from the E/T spectra with the use of a model based on ray optics. The spectra were in good quantitative agreement with absorbance spectra derived by the KBr pellet method for the same sample thickness. The E/T derived spectra were somewhat noisier than the KBr pellet spectra, but were free of Christiansen effect band distortions and scattering contributions. The E/T method has the additional advantage of requiring little or no sample preparation.

• A systematic search for cases of adult-onset hereditary ataxia was conducted on location in Scotland. The investigation resulted in the discovery of eight pedigrees with 42 patients of whom 16 were alive in 1975. Nine patients were examined by the authors and recent hospital records were available on the remaining seven. The clinical features were quite variable. In declining order of frequency, findings were gait and limb ataxia, dysarthria, hyperreflexia, extrapyramidal motor disturbances, impaired vibratory sense, spasticity, defects of extraocular movements and nystagmus, reflex depression, Babinski signs, impaired joint position sense, muscle weakness, optic atrophy, and mental abnormalities. Foot deformity occurred only once.Inheritance was compatible with autosomal dominant transmission, but complicated by consanguinity in two families. The minimum prevalence was calculated as 0.31/100,000. Autopsy in two members in one family revealed olivopontocerebellar degeneration.

Paramphistomosis, caused by the rumen fluke, Calicophoron daubneyi, is a parasitic infection of ruminant livestock which has seen a rapid rise in prevalence throughout Western Europe in recent years. Following ingestion of metacercariae (parasite cysts) by the mammalian host, newly-excysted juveniles (NEJs) emerge and invade the duodenal submucosa which causes significant pathology in heavy infections. The immature larvae then migrate upwards, along the gastrointestinal tract, and enter the rumen where they mature and begin to produce eggs. Despite their emergence, and sporadic outbreaks of acute disease, we know little about the molecular mechanisms used by C. daubneyito establish infection, acquire nutrients and to avoid the host immune response. Here, transcriptome analysis of four intra-mammalian life-cycle stages, integrated with secretome analysis of the NEJ and adult parasites (responsible for acute and chronic disease respectively), revealed how the expression and secretion of selected families of virulence factors and immunomodulators are regulated in accordance with fluke development and migration. Our data show that whilst a family of cathepsins B with varying S2 sub-site residues (indicating distinct substrate specificities) are differentially secreted by NEJs and adult flukes, cathepsins L and F are secreted in low abundance by NEJs only. We found that C. daubneyihas an expanded family of aspartic peptidases, which is up-regulated in adult worms, although they are underrepresented in the secretome. The most abundant proteins in adult fluke secretions were helminth defence molecules (HDMs) that likely establish an immune environment permissive to fluke survival and/or neutralise pathogen-associated molecular patterns (PAMPs) such as bacterial lipopolysaccharide in the microbiome-rich rumen. The distinct collection of molecules secreted by C. daubneyiallowed the development of the first coproantigen-based ELISA for paramphistomosis which, importantly, did not recognise antigens from other helminths commonly found as co-infections with rumen fluke.

A letter to the editor is presented in response to an article about the obsession of archaeologists with religion and subsistence.