Crystallization of and X-ray investigations on glucose dehydrogenase from Bacillus megaterium

The tetrameric glucose dehydrogenase from Bacillus megaterium M1286 belongs to the 'short' family of dehydrogenases with 262 amino acids per subunit (Mr approximately 30,000), and does not require Zn2+ for enzymatic action. It was crystallized as complex with its coenzyme NAD from a 1-2% protein solution by the batch method using ammonium sulfate as precipitant at pH 6.5. Crystals appeared within two days as clusters of large plates with maximum dimensions of 2 mm, which diffract X-rays to a resolution of at least 0.2 nm. The space group is orthorhombic P2(1)2(1)2(1), unit-cell dimensions are a = 15.03 nm, b = 10.42 nm and c = 6.74 nm. Assuming one molecule (approximately 120 kDa) per asymmetric unit the VM value is 0.0022 nm3/Da and the solvent content of the crystals is 45% based on a partial specific volume for the protein of 0.723 ml/g. The crystallization was further improved by using the microdialysis technique where instead of clusters, single crystals appeared within 7 days.     

New and noteworthyHabenaria spp. (Orchidaceae) from New Guinea and adjacent islands

5 new taxa ofHabenaria, namelyH. bougainvillae, H. elongata R. Br. var.leptophylla, H. ensigera, H. rechingeri andH. trichoglossa, are described and illustrated, with reference to affinities to related Australian and Indo-malayan species. The occurrence in New Guinea of severalHabenaria spp. typical for a savanna-like vegetation, led to look more thoroughly at these taxa:H. elongata R. Br. andH. ochroleuca R. Br., considered so far to be endemic in Northern Australia, andH. khasiana Hook. f., hitherto only known from southeastern Asia.Studies in the subtribeHabenariinae Bentham (Orchidaceae), 2.—Part 1: Candollea34, 357 (1979).Dedicated to Hofrat Prof. DrKarl Heinz Rechinger on the occasion of his 80th birthday. — On April 30, in the year 1927, the author and his brotherOtto Renz metKarl Heinz Rechinger on a small steam-boat in a stormy Aegaen Sea, travelling from Piraeus to the Northern Sporades Islands:Karl Heinz with destination to Chelidromia, the author andO. Renz to Skopelos. By this lucky chance a lasting friendship began.     

The three-dimensional structure of the bifunctional proteinase K/alpha-amylase inhibitor from wheat (PK13) at 2.5 A resolution

Wheat germ contains an inhibitor for proteinase K, called PK13 (Mr approximately 19,600) which simultaneously inhibits alpha-amylase. PK13 was crystallized, space group P21, a = 43.02 (5) A, b = 65.18 (7) A, c = 32.33 (4) A, beta = 112.79 degrees (9), X-ray data were collected to 2.5 A resolution, the structure solved by molecular replacement on the basis of the atomic coordinates of the homologous Erythrina caffra DE-3 inhibitor, and refined with simulated annealing techniques with a current R-factor of 21%. The three-dimensional structure of PK13 is stabilised by two disulfide bridges and has a central beta-barrel with distorted beta-structure. In analogy to related inhibitors, the binding site for proteinase K is assumed to be located on the surface of the protein (amino acid residues 66-67), although the 75-76 peptide bond is cleaved upon binding.     

Mucin gene expression in rat airways following infection and irritation.

Airway mucus hypersecretion occurs in response to infection and irritation and poses an important and poorly understood clinical problem. In order to gain insight into its pathogenesis, we have focused on an mRNA encoding the major mucus glycoprotein, mucin. Northern blots showed that mucin mRNA was abundant in the intestine of specific pathogen free rats whereas it was undetectable in the airways of these rats until pathogen-free conditions were suspended and rats acquired Sendai (Parainfluenza I) virus infections. Airway mucin hybridization signals in rats that were both infected with Sendai virus and exposed to SO2 were more intense than those in rats with infection alone. These results suggest that pathogen-and irritant-induced hypersecretion may be partly controlled at the level of mucin mRNA.     

Loriculus stigmatus croconotus subsp. nova

Ohne Zusammenfassung     

Neue Vogel-Formen von den Nord-Molukken

Ohne Zusammenfassung     

Effect of fixation on immunolocalization of transferrin and albumin in the liver of the adult rat

The influence of the fixation procedure on the localization of albumin and transferrin in adult rat liver has been carried out using an indirect immunoperoxidase technique at the light and electron microscopic levels. Perfusion and immersion fixations with different concentrations of paraformaldehyde (with or without addition of glutaraldehyde) have been investigated. According to the mode of fixation (perfusion versus immersion) and the concentration of the fixative, the number of albumin and transferrin containing hepatocytes could vary from 10% to 100%, and different labeling patterns could be observed at the electron microscopic level. For the same concentration of fixative, a perfusion fixation induces a less intense labeling than an immersion fixation. Thus similar results are obtained after immersion fixation in 6% paraformaldehyde + 0.25% glutaraldehyde or after perfusion fixation in 4% paraformaldehyde + 0.025% glutaraldehyde. Similar data are noticed after immersion fixation in 4% paraformaldehyde or after perfusion fixation in 1% paraformaldehyde + 0.025% glutaraldehyde. Moreover, perfusion fixation induced a more fine cell structure preservation than immersion fixations and avoided the appearance of zones of fixation.     

Une nouvelle méthode de marquage pour certains groupes d'Insectes et de Crustacés

A new technique of labelling, based on making series of microscars on the compound eye of immature insects, allows to recognize individual specimens, even after several moults.

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Une nouvelle méthode de marquage pour certains groupes d'Insectes et de Crustacés