No abstract

The SALMFamides are a family of neuropeptides that act as muscle relaxants in echinoderms. Two types of SALMFamides have been identified: L-type (e.g. the starfish neuropeptides S1 and S2) with the C-terminal motif LxFamide (x is variable) and F-type with the C-terminal motif FxFamide. In the sea urchin Strongylocentrotus purpuratus (class Echinoidea) there are two SALMFamide genes, one encoding L-type SALMFamides and a second encoding F-type SALMFamides, but hitherto it was not known if this applies to other echinoderms. Here we report the identification of SALMFamide genes in the sea cucumber Apostichopus japonicus (class Holothuroidea) and the starfish Patiria miniata (class Asteroidea). In both species there are two SALMFamide genes: one gene encoding L-type SALMFamides (e.g. S1 in P. miniata) and a second gene encoding F-type SALMFamides plus one or more L-type SALMFamides (e.g. S2-like peptide in P. miniata). Thus, the ancestry of the two SALMFamide gene types traces back to the common ancestor of echinoids, holothurians and asteroids, although it is not clear if the occurrence of L-type peptides in F-type SALMFamide precursors is an ancestral or derived character. The gene sequences also reveal a remarkable diversity of SALMFamide neuropeptides. Originally just two peptides (S1 and S2) were isolated from starfish but now we find that in P. miniata, for example, there are sixteen putative SALMFamide neuropeptides. Thus, the SALMFamides would be a good model system for experimental analysis of the physiological significance of neuropeptide “cocktails” derived from the same precursor protein.

The anisotropy of charge transport was investigated in the antiferromagnetic II state of GdB6 from precise measurements of transverse magnetoresistance. Based on the data obtained we detected a complicated behavior of magnetoresistance curves which are characterized by the appearance of considerable hysteresis on the field and angular dependences below TN2. Moreover it was shown that the system GdB6 is sensitive to coolingwarming prehistory. The data analysis allowed to reconstruct magnetic H−T phase diagram of GdB6 along main crystallographic directions (H 001 , 110 , 111 ) and to propose additional phase transition inside AF II phase at H1 ≈ 0.5 T.

The paper presents experimental results of investigations on the influence of temperature and thermo-chemical annealing on the structural and optical properties of YbAlO(3) crystals. Thermal behaviour of the crystal structure has been studied in the temperature range of 19-1173 K by means of in situ high-resolution x-ray powder diffraction using synchrotron radiation. Lattice expansion of YbAlO(3) displays a strongly anisotropic character: the relative expansion along the b direction is about two times smaller than that along the a and c axes. The influence of thermo-chemical annealing in oxidizing and reducing atmospheres has been studied by means of in situ optical spectroscopy. The increase of the absorption in the range of 300-600 nm during annealing in an oxidizing atmosphere as well as its bleaching during reduction has been observed in the temperature range 700-1000 K. The oxidation and reduction kinetics have been analysed by means of mathematical models taking into account diffusion and the quasi-chemical reaction of the defect centres.