A Cytopathogenic, Apoptosis-Inducing Variant of Hepatitis A Virus

A cytopathogenic variant of hepatitis A virus (HAV_cyt/HB1.1) was isolated from persistently infected BS-C-1 cells by serial passages in FRhK-4 cells. This virus shows a rapid replication pattern and high final titers are obtained, which are main characteristics of cytopathogenic HAVs. Sequencing of the nontranslated regions and the coding regions for 2ABC and 3AB revealed that mutations are distributed all over these regions and that certain mutated sites correspond to those in other cytopathogenic HAV variants. Investigating the mechanisms causing the cytopathic effect in FRhK-4 cells infected with this variant, we found that an apoptotic reaction takes place.     

Molecular Phylogeny of Metazoan Intermediate Filament Proteins

We have cloned cytoplasmic intermediate filament (IF) proteins from a large number of invertebrate phyla using cDNA probes, the monoclonal antibody IFA, peptide sequence information, and various RT-PCR procedures. Novel IF protein sequences reported here include the urochordata and nine protostomic phyla, i.e., Annelida, Brachiopoda, Chaetognatha, Echiura, Nematomorpha, Nemertea, Platyhelminthes, Phoronida, and Sipuncula. Taken together with the wealth of data on IF proteins of vertebrates and the results on IF proteins of Cephalochordata, Mollusca, Annelida, and Nematoda, two IF prototypes emerge. The L-type, which includes 35 sequences from 11 protostomic phyla, shares with the nuclear lamins the long version of the coil 1b subdomain and, in most cases, a homology segment of some 120 residues in the carboxyterminal tail domain. The S-type, which includes all four subfamilies (types I to IV) of vertebrate IF proteins, lacks 42 residues in the coil 1b subdomain and the carboxyterminal lamin homology segment. Since IF proteins from all three phyla of the chordates have the 42-residue deletion, this deletion arose in a progenitor prior to the divergence of the chordates into the urochordate, cephalochordate, and vertebrate lineages, possibly already at the origin of the deuterostomic branch. Four phyla recently placed into the protostomia on grounds of their 18S rDNA sequences (Brachiopoda, Nemertea, Phoronida, and Platyhelminthes) show IF proteins of the L-type and fit by sequence identity criteria into the lophotrochozoic branch of the protostomia. Received: 2 April 1998 / Accepted: 19 June 1998     

Lipase-catalyzed esterification of unusual substrates: Synthesis of glucuronic acid and ascorbic acid (vitamin C) esters

The synthesis of n-butanol and cinnamic alcohol esters of glucuronic acid and the esterification of ascorbic acid (vitamin C) with phenylbutyric acid was performed with lipase from Candida antarctica B (CAL-B, SP435) in a mainly solid-phase system. Products were obtained in 15 to 22 % yield. Computer modelling based on the structure of CAL-B was used to elucidate the access of glucuronic acid to the catalytic site of the lipase. A fixation of glucuronic acid via H-bonds to Q157, D134 and H224 during the transition state was observed. © Rapid Science Ltd. 1998     

Synthesis of aromatic n-alkyl-glucoside esters in a coupled β-glucosidase and lipase reaction

Regioselective synthesis of e.g. 6-O-phenylbutyryl-1-n-butyl--D-glucopyranose was achieved in 21 % yield using almond--glucosidase and Candida antarctica lipase B. The -glucosidase reaction was performed in a biphasic (buffer/n-alcohol) system using free and Eupergit CTM-immobilized glucosidase. Immobilized enzyme allowed product formation even at a water content of 1 %. © Rapid Science Ltd. 1998     

Structure and biodiversity of megabenthos in the Weddell and Lazarev Seas (Antarctica): ecological role of physical parameters and biological interactions

A community analysis of the mega-zooepibenthos at water depths between 99 and 1243 m was carried out for the Weddell and Lazarev Seas (47°W 77°S–12°E 70°S). A total of 144,531 specimens were counted and 313 taxa were identified from 3,768 photographs at 55 stations, which represented approximately 3,304 m² of seafloor. The stations were classified into six groups according to their inventory of taxa although they represented rather a gradient from a rich and diverse suspension feeder assemblage to a poorer assemblage. In the latter, the proportion of deposit feeders was higher than in the former. A statistical comparison between biological and physical data showed that the faunistic pattern could best be explained by a combination of water depth and a geographical gradient. A positive correlation between the abundance of large sponges and the number of all other taxa was found. Received: 16 September 1997 / Accepted: 11 April 1998     

Microsensors as a tool to determine chemical microgradients and bacterial activity in wastewater biofilms and flocs

Microsensors used in microbial ecology are reviewed with emphasis on new sensor developments (NO₃ ^-, NO₂ ^-, NH₄ ⁺, CO₂, H₂, H₂S and CH₄ microsensors as well as fiberoptical microsensors for O₂, temperature and pH). Examples of microsensor applications in biofilms and activated sludge flocs are presented, where sulfate reduction and denitrification were studied.     

Der3p/Hrd1p Is Required for Endoplasmic Reticulum-associated Degradation of Misfolded Lumenal and Integral Membrane Proteins

We have studied components of the endoplasmic reticulum (ER) proofreading and degradation system in the yeast Saccharomyces cerevisiae. Using a der3–1 mutant defective in the degradation of a mutated lumenal protein, carboxypeptidase yscY (CPY*), a gene was cloned which encodes a 64-kDa protein of the ER membrane. Der3p was found to be identical with Hrd1p, a protein identified to be necessary for degradation of HMG-CoA reductase. Der3p contains five putative transmembrane domains and a long hydrophilic C-terminal tail containing a RING-H2 finger domain which is oriented to the ER lumen. Deletion of DER3 leads to an accumulation of CPY* inside the ER due to a complete block of its degradation. In addition, a DER3 null mutant allele suppresses the temperature-dependent growth phenotype of a mutant carrying the sec61–2 allele. This is accompanied by the stabilization of the Sec61–2 mutant protein. In contrast, overproduction of Der3p is lethal in a sec61–2 strain at the permissive temperature of 25°C. A mutant Der3p lacking 114 amino acids of the lumenal tail including the RING-H2 finger domain is unable to mediate degradation of CPY* and Sec61–2p. We propose that Der3p acts prior to retrograde transport of ER membrane and lumenal proteins to the cytoplasm where they are subject to degradation via the ubiquitin-proteasome system. Interestingly, in ubc6-ubc7 double mutants, CPY* accumulates in the ER, indicating the necessity of an intact cytoplasmic proteolysis machinery for retrograde transport of CPY*. Der3p might serve as a component programming the translocon for retrograde transport of ER proteins, or it might be involved in recognition through its lumenal RING-H2 motif of proteins of the ER that are destined for degradation.     

PDB2MultiGIF: A Web Tool to Create Animated Images of Molecules

A new web tool, PDB2MultiGIF (http://www.dkfz-heidelberg.de/spec/pdb2mgif/),which converts the topological information (atom types, 3D coordinates, molecular connectivity) of molecules (given in PDB format [1]) to a series of animated images (in GIF Format) [2] is described. The molecular visualisation program RASMOL [3] is used to generate the images.Electronic Supplementary Material available.     

The evolution of recombination in changing environments

Recombination generates under-represented genotypes by breaking down linkage disequilibrium between genes. Recent analyses have specified the conditions under which recombination is favored. These conditions are surprisingly sensitive to the form of selection and environmental change. This quantification makes it possible to use empirical measurements of critical parameters such as the form of epistasis, the rate of mutation, and the frequency of beneficial sweeps to assess different hypotheses for the evolution of recombination.