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The molecular sensor of innocuous (painless) cold sensation is well-established to be transient receptor potential cation channel, subfamily M, member 8 (TRPM8). However, the role of transient receptor potential cation channel, subfamily A, member 1 (TRPA1) in noxious (painful) cold sensation has been controversial. We find that TRPA1 channels contribute to the noxious cold sensitivity of mouse somatosensory neurons, independent of TRPM8 channels, and that TRPA1-expressing neurons are largely non-overlapping with TRPM8-expressing neurons in mouse dorsal-root ganglia (DRG). However, relatively few TRPA1-expressing neurons (e.g., responsive to allyl isothiocyanate or AITC, a selective TRPA1 agonist) respond overtly to cold temperature in vitro, unlike TRPM8-expressing neurons, which almost all respond to cold. Using somatosensory neurons from TRPM8-/- mice and subtype-selective blockers of TRPM8 and TRPA1 channels, we demonstrate that responses to cold temperatures from TRPA1-expressing neurons are mediated by TRPA1 channels. We also identify two factors that affect the cold-sensitivity of TRPA1-expressing neurons: (1) cold-sensitive AITC-sensitive neurons express relatively more TRPA1 transcripts than cold-insensitive AITC-sensitive neurons and (2) voltage-gated potassium (KV) channels attenuate the cold-sensitivity of some TRPA1-expressing neurons. The combination of these two factors, combined with the relatively weak agonist-like activity of cold temperature on TRPA1 channels, partially explains why few TRPA1-expressing neurons respond to cold. Blocking KV channels also reveals another subclass of noxious cold-sensitive DRG neurons that do not express TRPM8 or TRPA1 channels. Altogether, the results of this study provide novel insights into the cold-sensitivity of different subclasses of somatosensory neurons.

Cone snails in the Virgiconus clade prey on marine worms. Here, we identify six related conotoxins in the O1-superfamily from three species in this clade, Conus virgo, Conus terebra and Conus kintoki. One of these peptides, vi6a, was directly purified from the venom of C. virgo by following its activity using calcium imaging of dissociated mouse dorsal root ganglion (DRG) neurons. The purified peptide was biochemically characterized, synthesized and tested for activity in mice. Hyperactivity was observed upon both intraperitoneal and intracranial injection of the peptide. The effect of the synthetic peptide on DRG neurons was identical to that of the native peptide. Using the vi6a sequence, five other homologs were identified. These peptides define a glycine-rich subgroup of the O1-superfamily from the Virgiconus clade, with biological activity in mice.

The alpha-conotoxin family is comprised of peptides that share the following arrangement of cysteine residues in the primary amino acid sequence: -CC-C-C-, where each dash represents a variable number of amino acids. The number of amino acids between cysteine residues has been used to group the alpha-conotoxins into distinct subfamilies. These subfamilies include the alpha 4/7-, alpha 4/3- and alpha 3/5-conotoxins, so named for the number of amino acids between 2nd/3rd and 3rd/4th cysteine residues, respectively. The alpha 3/5-conotoxins antagonize vertebrate-muscle nicotinic acetylcholine receptors (nAChRs), while the alpha 4/7- and alpha 4/3-conotoxins primarily inhibit vertebrate neuronal nAChRs. To date, these three subfamilies are the most extensively characterized of the alpha-conotoxin family. Here we report the purification and characterization of an unusual alpha 4/4-conotoxin, alpha-conotoxin PIB (alpha-PIB), from the venom of Conus purpurascens, with the following amino-acid sequence: ZSOGCCWNPACVKNRC (Z=pyroglutamate, O=hydroxyproline). This peptide demonstrates high affinity inhibition of vertebrate-muscle nAChRs, and paralytic effects when injected in vivo. Testing of alpha-PIB against other receptors indicated that the inhibitory effect is specific for skeletal muscle nAChRs. alpha-PIB shares the key biochemical and pharmacological characteristics of the alpha-conotoxin family.

We have characterized the defining members of a novel subfamily of excitatory conotoxins, the short kappaA-conotoxins (kappaA(S)-conotoxins). kappaA-conotoxins PIVE and PIVF (kappaA-PIVE and kappaA-PIVF) were purified from Conus purpurascens venom. Both peptides elicited excitatory activity upon injection into fish. kappaA-PIVE was synthesized for further characterization. The excitatory effects of kappaA-PIVE in vivo were dose dependent, causing hyperactivity at low doses and rapid immobilization at high doses, symptomatic of a type of excitotoxic shock. Consistent with these observations, kappaA-PIVE caused repetitive action potentials in frog motor axons in vitro. Similar results have been reported for other structurally distinct conotoxin families; such peptides appear to be required by most fish-hunting cone snails for the rapid immobilization of prey. Unexpected structure-function relationships were revealed between these peptides and two families of homologous conotoxins: the alphaA-conotoxins (muscle nAChR antagonists) and kappaA-conotoxins (excitotoxins), which all share a common arrangement of cysteine residues (CC-C-C-C-C). Biochemically, the kappaA(S)-conotoxins more closely resemble the alphaA(S)-conotoxins than the other kappaA-conotoxin subfamily, the long kappaA-conotoxins (kappaA(L)-conotoxins); however, kappaA(S)- and alphaA(S)-conotoxins produce different physiological effects. In contrast, the kappaA(S)-and kappaA(L)-conotoxins that diverge in several biochemical characteristics are clearly more similar in their physiological effects.

The venoms of cone snails are rich in multiply disulfide-crosslinked peptides, the conotoxins. Conotoxins are grouped into families on the basis of shared cysteine patterns and homologous molecular targets. For example, both the kappaA- and alphaA-conotoxin families share the same Class IV Cys pattern (-CC-C-C-C-C-), but differ in their molecular targets. The kappaA-conotoxins are excitatory toxins that purportedly block potassium channels, while the alphaA-conotoxins are paralytic conotoxins that inhibit nicotinic acetylcholine receptors (nAChRs). In this work, we describe the isolation and characterization of a novel Conus peptide from venom milked from Hawaiian specimens of Conus obscurus. This peptide shares the Class IV Cys pattern but differs from both previously characterized alphaA- and kappaA-conotoxins in the spacing of amino acids between Cys resides. However, the peptide is similar to previously characterized alphaA-conotoxins in its paralytic effects on fish and its antagonist activity on the neuromuscular nAChR. Unexpectedly, the peptide differs in its disulfide bonding from alphaA-conotoxin PIVA. We have named this unique peptide alphaA-conotoxin OIVA, and we consider it the defining member of a subfamily of alphaA-conotoxins that we designate the alphaA(1-3)-conotoxins to identify them by their unique disulfide bonding framework. These results indicate that the alphaA-conotoxin family is both more structurally diverse and broadly distributed than previously believed.

The nucleus 69Ge has been studied in the reactions 66Zn(α,n)69Ge and 60Ni(12C,2pn)69Ge. Using γ-spectroscopic methods energies, intensities, excitation functions, γγ-coincidences, angular distributions, and the linear polarization of γ-rays as well as lifetimes were measured. From the α-induced reaction, states up to spin J = 212 and Ex = 4267 keV have been established in 69Ge including 178 new transitions and 62 new levels. Spin and parity were determined for 79 levels. High-spin states populated via the reaction 12C + 60Ni show 61 new transitions and 27 new levels up to spin J = 372 and Ex = 9182 keV. For 19 levels ps-lifetimes were determined. Eight complete multiplets originating from the coupling of the odd neutron to the core 68Ge have been identified and candidates for further multiplets are proposed. Significant deviations from the simple De-Shalit core-coupling model were found. Shell-model calculations, which were performed for 68Ge and 69Ge with the code RITSSCHIL on a parallel computer in a large configuration space, show that proton excitations from the 2p32 to higher shells play an important role for the detailed structure of the particle-core multiplets.

Two types of Compton polarimeters for γ-linear polarization measurements are presented. The first one consists of standard Ge-detectors and unites an easy handling and high grade of universality with high polarization sensitivity in the γ-ray energy range 180–2500 keV. In this device, a low efficiency Ge-crystal scatterer is used with a special diameter-to-length ratio which optimizes the probability for Compton scattering. In addition, the background in the summed energy spectra is significantly reduced by requiring coincident γ-ray energies to obey the Compton scattering formula. The second device fits the need of accessory units which can be used with the new generation of multi-detector arrays. It is based on a segmented planar Ge-crystal surrounded by an anti-Compton shield and possesses a high coincidence efficiency in the 50–1000 keV range. For both spectrometers we performed calibration measurements to obtain the sensitivity Q and the coincidence efficiency e c . From these values we deduced the “figure of merit” F = Q 2 e c which gives a kind of quality description for polarimeters.

The energy resolution of a n-type HPGe detector has been measured as function of the operating temperature before and after inducing radiation damage by neutrons from a fusion evaporation reaction. The aim of the investigation was to determine an appropriate operating temperature for Ge multidetector arrays. In the undamaged condition the leakage current due to thermal production of charge carriers limits the operating temperature to below 125 K. With neutron induced trapping levels the operating temperature has to be decreased to below 100 K because of thermal activation of trapping levels and defect migrations.

Excited states of 73Kr have identified by in-beam γ-ray spectroscopy via the reaction 40Ca(36Ar, 2pn)73Kr. A strongly coupled band is interpreted as a prolate band built on the Nilsson [312] 3 2 − orbital at β2∼0.4, while a decoupled g 9 2 band is likely to correspond to a small deformation. Evidence for a large oblate deformation as discussed for 72Kr has not been found.

The aim of the EUROBALL project is the development of γ-ray detectors with substantially improved qualities, and the realization of large solid angle arrays, in particular of 4π spectrometers employing these detectors. This article especially focusses on the development of a Cluster detector consisting of seven large hexagonal tapered and encapsulated Ge detectors which are surrounded by a common BGO anti-Compton shield. First results of the properties of a hexagonal tapered Ge detector and of an encapsulated Ge detector are presented.

The proposals of the EUROBALL Design Group for the development of large composite Ge detectors for an improved 4π detector array with a total full energy peak efficiency of p ph > 0.15 are presented. Cluster detectors are composed of hexagonal tapered coaxial Ge detectors while Stack detectors are composed of large diameter planar detectors. The status of the development is discussed and first experimental results of the properties of a hexagonal tapered Ge detector are presented.

γ-rays from the decay of excited states in the neutron deficient nucleus 69Se could be identified from the reaction 32S(40Ca, 2pn)69Se. In 71Se the unfavoured g 9 2 band was established using the reaction 16O(58Ni, 2pn) 71Se. γ-spectroscopic investigation revealed an oblate structure of the g 9 2 bands in both nuclei.