Distribution of polyamines in methanogenic bacteria

Members of all four families of methanogenic bacteria were analyzed for polyamine concentrations. High-performance liquid chromatography analysis of dansylated cell extracts revealed typical polyamine patterns for each family. Members of Methanobacteriaceae (family I) were characterized by very low polyamine concentrations; members of Methanococcaceae (family II) were characterized by putrescine and high spermidine concentrations; members of Methanomicrobiaceae (family III) were characterized by the presence of putrescine, spermidine, and sym-homospermidine; and members of Methanosarcinaceae (family IV) contained only high concentrations of sym-homospermidine in addition to putrescine. The highest polyamine concentration was found in Methanosarcina barkeri Jülich, with 0.35% putrescine in the dry cell material. The polyamine distribution found coincides with the dendrogram based on comparative cataloguing of 16S rRNA and offers a new, rapid chemotaxonomic method for characterizing methanogenic bacteria. Variation of the growth substrates (H2-CO2, methanol, acetate, and trimethylamine) for M. barkeri resulted in quantitative but not qualitative differences in polyamine composition.     

Mechanism of α Factor Biosynthesis in Saccharomyces cerevisiae

The biosynthesis of alpha factor, a mating-type-specific regulatory oligopeptide which is secreted by Saccharomyces cerevisiae cells of alpha mating type, was studied. In batch cultures only small amounts of the peptide were synthesized during the exponential growth phase. During the stationary phase, alpha factor was produced at a constant rate and accumulated in the culture medium. Inhibition of translation in wild-type cells by cycloheximide, or in mutant strains under conditions which blocked protein or ribonucleic acid (RNA) synthesis completely inhibited the production of alpha factor. These results indicate that the factor is produced by ribosomal translation of a specific messenger RNA and not by an extraribosomal mechanism of peptide synthesis.     

Fundamentals of an applied ecosystem research project in the Wadden Sea of Schleswig-Holstein

The aims, content, and organisatory structure of a proposed interdisciplinary ecosystem research project in the Wadden Sea of Schleswig-Holstein (W. Germany) are briefly presented. The project will include research on both fundamental as well as applied aspects of the Wadden Sea ecosystems and their interaction with local human activities. In contrast to most of the other completed or currently running ecosystem research projects on tidal coasts, a considerable part of the scientific work will also deal with aspects of ecosystem management and protection of the various marine and semiterrestrial habitats of the Wadden Sea. Considerable attention is paid to theoretical and methodological aspects of research on ecosystems and landscape units. In particular, the adoption of a hierarchical view of complex biological and environmental systems is recommended. Presented at the VI International Wadden Sea Symposium (Biologische Anstalt Helgoland, Wattenmeerstation Sylt, D-2282 List, FRG, 1–4 November 1988)     

Gene mapping on mouse chromosome 8 by interspecific crosses: new data on a linkage group conserved on human chromosome 16q

A large conserved linkage group exists on mouse chromosome 8 and human chromosome 16q, including the loci for chymotrypsinogen B (Ctrb), haptoglobin (Hp), lecithin:cholesterol acyltransferase (Lcat), metallothionein-1,-2 (Mt-1,-2), tyrosine aminotransferase (Tat), and uvomorulin (Um). Using cloned gene probes, these six loci were mapped in M. m. domesticus X M. spretus interspecific crosses relative to a number of chromosome 8 anchor loci resulting in the gene order Es-1,Es-9-Mt-1,-2-Got-2-Es-2,Es-7,Lcat,Um-Hp,Tat,Ctrb-e. These results complement earlier studies and redefine the conserved segment on mouse chromosome 8, previously defined by the Hp-Tat interval, by the 24-cM interval between Mt-1,-2 and the conserved locus for adenine phosphoribosyltransferase, Aprt, mapped at 25 cM from Es-1 by T. B. Nesterova, P. M. Borodin, S. M. Zakian, and O. L. Serov (1987, Biochem. Genet. 25: 563-568). Within this segment, the gene order appears the same in man and mouse. While map distances between HP-TAT,HP-CTRB, and TAT-CTRB of respectively 7, 11, and 9 cM have previously been measured in man, no crossovers between Hp, Tat, and Ctrb were observed in over 100 meioses in the mouse.     

Arachidonic acid metabolites alter G protein-mediated signal transduction in heart. Effects on muscarinic K+ channels

The muscarinic acetylcholine receptor (mAChR)-stimulated, inwardly rectifying K+ current (IK [ACh]) was examined in single bullfrog atrial cells using the whole-cell patch clamp technique. IK[ACh] was activated either by bath addition of 1 microM ACh or via activation of the G protein, Gk, with guanosine-gamma-thiotriphosphate (GTP gamma S). Arachidonic acid (AA) modulated IK[ACh] under both conditions. AA decreased mAChR-stimulated IK[ACh] and increased the rate of decay from the peak current (desensitization). In addition, AA affected GTP gamma S-activated IK[ACh] by modulation of Gk. The effects of AA and its metabolites on Gk were assessed by examining their effects on both the basal rate of Gk activation by GTP gamma S, and the mAChR-mediated increase in activation rate produced by nanomolar ACh. AA increased the basal rate of GTP gamma S-mediated IK[ACh] activation, but reduced the ACh-induced augmentation of this rate. All of the effects of AA on GTP gamma S-mediated IK[ACh] activation were produced by metabolites. A lipoxygenase inhibitor, nordihydroguaiaretic acid (NDGA), decreased the basal and ACh-enhanced rate of IK[ACh] activation in both the presence and absence of exogenous AA. In contrast, indomethacin (INDO), a cyclooxygenase inhibitor, increased the basal rate of IK[ACh] activation by GTP gamma S in both the presence and absence of exogenous AA, and reversed the effects of AA on the ACh-augmented basal rate. AA metabolites produced via lipoxygenase and cyclooxygenase pathways thus have opposing effects on the signal transduction pathway from mAChR to IK[ACh]. We directly tested a lipoxygenase pathway metabolite, LTC4, on GTP gamma S-mediated IK[ACh] activation and found that it not only overcame the inhibitory effects of NDGA, but also increased both the basal and ACh-augmented rate of IK[ACh] activation. From these data, we propose that AA metabolites modulate the function of Gk by altering its kinetic properties.     

Duplication of an Xp segment that includes the ZFX locus causes sex inversion in man

Summary Two 46,XY females with tandem duplications of an X short arm segment were studied by cytogenetic and Southern blot analysis. The results show that the duplicated segment in each case included the Xp21.2–Xp22.2 interval, resulting in a double dose of ZFX on the single active X chromosome. The results from our two cases, in conjunction with those reported by other workers, lead us to conclude that the duplication is the reason for the sex inversion. If ZFY and ZFX are indeed sex-determining gene loci, these findings favour a model of sex determination characterized by antagonistic interaction between these genes.     

Identification and purification of a family of dimeric major cold shock protein homologs from the psychrotrophic Bacillus cereus WSBC 10201.

Whole-cell protein patterns of a psychrotrophic Bacillus cereus strain from cultures grown at 7 and 30 degrees C were compared. This analysis revealed that at least three major proteins are expressed at a significantly higher rate at 7 degrees C than at 30 degrees C. The most abundant of these cold-induced proteins was a small polypeptide of 7.5 kDa, designated CspA, of B. cereus. In addition, four small proteins very similar in size to CspA were seen on both 7 degrees C and 30 degrees C two-dimensional protein gels. Immunoblot analysis using B. cereus anti-CspA antibodies indicated that the five proteins described above plus an additional sixth protein not visible on silver-stained two-dimensional gels are members of a B. cereus cold shock protein family. This hypothesis was corroborated by cloning and sequencing of the genes encoding five proteins of this family. The protein sequences deduced are highly similar and show homology to small procaryotic cold shock proteins and to the cold shock domain of eucaryotic Y-box proteins. Besides CspA, only one of the additional five CspA homologs was slightly cold inducible. In the presence of 100 mM NaCl, the two purified members of the protein family (CspA and CspE) elute as dimers at an apparent molecular mass of 15 kDa from a gel filtration column. At higher salt concentrations, they dissociate into their monomers. Their ability to bind to the ATTGG motif of single-stranded oligonucleotides was demonstrated by band shift analysis.     

Nucleotide sequence and taxonomical distribution of the bacteriocin gene lin cloned from Brevibacterium linens M18.

Linocin M18 is an antilisterial bacteriocin produced by the red smear cheese bacterium Brevibacterium linens M18. Oligonucleotide probes based on the N-terminal amino acid sequence were used to locate its single copy gene, lin, on the chromosomal DNA. The amino acid composition, N-terminal sequence, and molecular mass derived from the nucleotide sequence of an open reading frame of 798 nucleotides coding for 266 amino acids found on a 3-kb BamHI restriction fragment correspond closely to those obtained from the purified protein (N. Valdés-Stauber and S. Scherer, Appl. Environ. Microbiol. 60:3809-3814, 1994). No sequence homology to any protein or nucleotide sequences deposited in databases was found. Comparison of the nucleotide sequence and the N-terminal amino acid sequence derived from the protein suggests that B. linens M18 produces an N-formyl-methionyl-CAC tRNA. A wide taxonomical distribution of the gene within coryneform bacteria has been demonstrated by PCR amplification. The structural gene from linocin M18 is present at least in three Brevibacterium species, five Arthrobacter species, and five Corynebacterium species.     

Fine mapping of the Autosomal Dominant Split Hand/Split Foot Locus on Chromosome 7, Band q21.3-q22.1

Split hand/split foot (SHFD) is a human developmental defect characterized by missing digits, fusion of remaining digits, and a deep median cleft in the hands and feet. Cytogenetic studies of deletions and translocations associated with this disorder have indicated that an autosomal dominant split hand/split foot locus (gene SHFD1) maps to 7q21-q22. To characterize the SHFD1 locus, somatic cell hybrid lines were constructed from cytogenetically abnormal individuals with SHFD. Molecular analysis resulted in the localization of 93 DNA markers to one of 10 intervals surrounding the SHFD1 locus. The translocation breakpoints in four SHFD patients were encompassed by the smallest region of overlap among the SHFD-associated deletions. The order of DNA markers in the SHFD1 critical region has been defined as PON–D7S812–SHFD1–D7S811–ASNS. One DNA marker, D7S811, detected altered restriction enzyme fragments in three patients with translocations when examined by pulsed-field gel electro-phoresis (PFGE). These data map SHFD1, a gene that is crucial for human limb differentiation, to a small interval in the q21.3-q22.1 region of human chromosome 7.