Structural and functional relationships between Pasteurella multocida and enterobacterial adenylate cyclases.

The Pasteurella multocida adenylate cyclase gene has been cloned and expressed in Escherichia coli. The primary structure of the protein (838 amino acids) deduced from the corresponding nucleotide sequence was compared with that of E. coli. The two enzymes have similar molecular sizes and, based on sequence conservation at the protein level, are likely to be organized in two functional domains: the amino-terminal catalytic domain and the carboxy-terminal regulatory domain. It was shown that P. multocida adenylate cyclase synthesizes increased levels of cyclic AMP in E. coli strains deficient in the catabolite gene activator protein compared with wild-type strains. This increase does not occur in strains deficient in both the catabolite gene activator protein and enzyme III-glucose, indicating that a protein similar to E. coli enzyme III-glucose is involved in the regulation of P. multocida adenylate cyclase. It also indicates that the underlying process leading to enterobacterial adenylate cyclase activation has been conserved through evolution.     

Characterization and regional mapping of new anonymous chromosome 20-specific DNA markers isolated from a flow-sorted DNA library

Employing the flow-sorted chromosome 20-specific DNA library LL20NS01, we isolated seven novel unique poly- and monomorphic DNA markers specific to human chromosome 20. Initially, 201 phage clones were analyzed regarding insert size and repetitivity. By testing 14 single- and low-copy number clones for their ability to detect RFLPs, three polymorphisms were revealed by two probes, pFMS22-1.4 [D20S22] and pFMS76 [D20S23]. Seven of twenty probes (35%) were assigned to chromosome 20 using a somatic cell hybrid DNA panel. Five of them were regionally mapped by in situ hybridization. Three DNA markers, pFMS51 [D20S29], pFMS76 [D20S23], and pFMS106 [D20S30], were assigned to 20p11.2-p12, and two markers, pFMS22-1.4 [D20S22] and pFMS135 [D20S31], to 20q12-q13.3. Our new chromosome 20-specific DNA markers should be useful for the molecular characterization of this rather underpopulated human chromosome.     

Specificity and pH dependence for acylproline cleavage by prolidase

Catalytic pH dependence for the hydrolytic activity of the enzyme prolidase with a series of dipeptide substrates is found to be generally bell-shaped (kcat/Km) or simple sigmoidal (kcat). An enzymic residue with a pKa value of 6.6 is found to be critically involved in the catalytic mechanism, as is the substrate amino group. Significant catalysis at a pH of 6.6 is also observed for prolidase with (alkylthio)acetylprolines and with haloacetylprolines. A reverse-protonation state mechanism for substrate binding and activation is postulated, involving a chelative interaction of the aminoacylamide portion of substrate with a strongly Lewis-acidic active site metal ion.     

A locus for familial hypertrophic cardiomyopathy is closely linked to the cardiac myosin heavy chain genes, CRI-L436, and CRI-L329 on chromosome 14 at q11-q12

We report that a gene responsible for familial hypertrophic cardiomyopathy (HC) is closely linked to the cardiac alpha and beta myosin heavy chain (MHC) genes on chromosome 14q11. We have recently shown that probe CRI-L436, derived from the anonymous DNA locus D14S26, detects a polymorphic restriction fragment that segregates with familial HC in affected members of a large Canadian family. Using chromosomal in situ hybridization, we have mapped CRI-L436 to chromosome 14 at q11-q12. Because the cardiac MHC genes also map to this chromosomal band, we have determined the genetic distances between the cardiac beta MHC gene, D14S26, and the familial HC locus. Data presented here show that these three loci are linked within 5 centimorgans on chromosome 14 at q11-q12. The possibility that defects in either the cardiac alpha or beta MHC genes are responsible for familial HC is discussed.     

Stimulation of the anaerobic growth ofSalmonella typhimurium by reduction ofl-carnitine,carnitine derivatives and structure-related trimethylammonium compounds

In view of the development of al-carnitine deficiency, the metabolism ofl-carnitine and structure-related trimethylammonium compounds was studied inSalmonella typhimurium LT₂ by means of thin-layer chromatography (TLC).l-Carnitine, crotonobetaine and acetyl-l-carnitine stimulated the anaerobic growth in a complex medium significantly. The stimulation depended on the formation of -butyrobetaine. The reduction ofl-carnitine proceeded in two steps: (1) Dehydration of thel-carnitine to crotonobetaine, (2) hydrogenation of crotonobetaine to -butyrobetaine. The reduction of crotonobetaine was responsible for the growth stimulation. Terminal electron acceptors of the anaerobic respiration such as nitrate and trimethylamine N-oxide, but not fumarate, suppressed the catabolism ofl-carnitine completely. Glucose fermentation, too, inhibited the reduction ofl-carnitine but optimal growth with a high carnitine catabolism was achieved byd-ribose. The esters of carnitine with medium- and long-chain fatty acids inhibited the growth considerably because of their detergent properties.Abbreviations TLC thin-layer chromatography     

Serological studies on lithotrophic,ammonia oxidizing bacteria

Rabbit antisera were prepared against living cells of six different ammonia oxidizing nitrifying bacteria. They were examined as to cross-reactivity in the agglutination test (Microtiter-system) with 24 nitrifier strains, including members of all known genera.Usually distinct cross-reactions were obtained only within the genera, but some exceptions were noticed. There was stated a clear cross-reaction between the two anti-Nitrosospira-antisera and the four tested Nitrosolobus strains. In some cases cross-reactions between cells of the Nitrosovibrio strains and the anti-Nitrosospira- as well as the anti-Nitrosococcus-antisera could be observed. The interpretation of the results obtained with the Nitrosomonas group was complicated by the fact that all strains showed positive zero titers with the control sera. In seven cases lipopolysaccharides were isolated and tested in the passive hemagglutination test to their cross-reactivity with the above mentioned antisera. hemagglutination could only be observed in the homologous system, cross-reactivity was never expressed.Abbreviations LPS Lipopolysaccharide(s) - G+C Guanine + cytosine - PBS Phosphate-buffered saline - SRBC Sheep red blood cells     

Isolation of a moderate halophilic ammonia-oxidizing bacterium,Nitrosococcus mobilis nov. sp.

An ammonia-oxidizing bacterium was isolated from a sample of brackish water (North Sea, Harbour of Husum). It is a motile large coccus 1.5–1.7 m in diameter. The extensive cytomembrane system occurring as flattened vesicles in the peripheral region of the cytoplasm and as intrusions into the center of the cytoplasm is to be emphasized as a characteristic mark of identification. The lithoauto-trophically growing bacterium turned out to be an obligate halophile. Because of its physiological and morphological properties, we assigned it to the genus Nitrosoccus and propose the name Nitrosococcus mobilis.     

Alterations in plasma concentrations of testosterone, LH, and prolactin associated with mating in the male rat.

The hormonal response of the male rat to sexual activity was investigated in two studies. In the first, no evidence of a chronic elevation in plasma levels of testosterone (T), LH, or prolactin (PRL) was observed in sexually experienced rats compared to naive controls. Both groups showed an acute increase in plasma levels of all three hormones following mating, but the increases shown by the experienced group were more pronounced. In the second study, plasma levels of T, LH and PRL rose in sexually experienced male rats following exposure to a mating arena whether it contained an estrous female, an anestrous female, or no other animal. However, the increases were considerably larger in the group exposed to estrous females. It is suggested that plasma hormones rise in anticipation of mating, although not to the same extent as following mating, and that the anticipatory rise may function to initiate or facilitate mating behavior.     

Dual wavelength/stopped flow spectrophotometry: computer acquisition and analysis.

The adaptation of a commercially available dual wavelength/stopped flow spectrophotometer for use with turbid samples is described. A minicomputer is used to collect and analyze the data, thereby facilitating these experiments. The stopped flow/computer combination has a dead time in the single wavelength mode of 3.5 msec. In the dual wavelength mode, accurate determinations can be made of the time course of reactions that have a $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of 50 msec or longer. The application of this stopped flow spectrophotometer to the measurement of cytochrome P-450 reductase activity in rat liver microsomes is described.     

A murine monoclonal antibody directed against a yeast cell wall glycoprotein antigen of the yeast genus Saccharomyces

Abstract Murine monoclonal antibodies (mAbs) were selected against a cell wall glycoprotein of Saccharomyces cerevisiae . One of the mAbs (92-276/018) specifically identified S. cerevisiae and the sibling species S. paradoxus, S. pastorianus and S. bayanus in immunofluorescence studies and immunoblot analyses, while no other yeast genera except Saccharomyces were recognized. Further analysis indicated that the mAb 92-276/018 reacts with an epitope in the carbohydrate chain of the cell wall glycoproteins.