Phage resistance and altered growth habit in a strain of Streptococcus bovis

Bacteriophage (phi Sb01) of Streptococcus bovis, isolated from pooled rumen fluid of cattle, was a small siphovirus of morphotype B1. It contained double-stranded DNA of length 30.9 kb, which was digested by the restriction endonucleases, EcoRI, HindIII, and PvuII. Bacteria which survived phi Sb01 infection (strain 2BAr) grew in long chains (100-200 cells), ultimately forming large clumps of cells. This growth habit was in distinct contrast to that of the parent host strain which grew predominantly in the form of single cells or diplococci. Strain 2BAr was genetically stable, resistant to phi Sb01 attack, and the observed differences in the growth characteristics of the parent strain and 2BAr indicated that cells of 2BAr were more adherent. In the rumen ecosystem, the selection of phage-resistant bacteria with altered growth characteristics may be a factor in modifying bacterial phenotypes, and thus increasing variability among bacteria which are closely related genetically.     

The benthic phase of the life cycle ofParapenaeus longirostris (Crustacea,Decapoda, Penaeidae) along the Mediterranean coast of Israel

The population ofP. longirostris along the Mediterranean coast of Israel spends the benthic phase of its life cycle (from body size over 15 mm) on muddy bottom deeper than 45 m. New age groups are recruited within the depth zone of 45–300 m and migrate in both inshore and offshore directions. Inshore migration is limited by unsuitable sandy ground. The limiting line for offshore migration was not found.An age group could be detected during one year within a body size range of TL = 40 mm to TL = 84.5 mm for males and to TL = 102.5 mm for females. Reproductive activity in shallow water, down to a depth of 73 m, takes place during the whole year, while in depths of 150–300 m there is an arrest of reproductive activity from June to August.     

A simplified methylcoenzyme M methylreductase assay with artificial electron donors and different preparations of component C from Methanobacterium thermoautotrophicum delta H.

Different preparations of the methylreductase were tested in a simplified methylcoenzyme M methylreductase assay with artificial electron donors under a nitrogen atmosphere. ATP and Mg2+ stimulated the reaction. Tris(2,2'-bipyridine)ruthenium (II), chromous chloride, chromous acetate, titanium III citrate, 2,8-diaminoacridine, formamidinesulfinic acid, cob(I)alamin (B12s), and dithiothreitol were tested as electron donors; the most effective donor was titanium III citrate. Methylreductase (component C) was prepared by 80% ammonium sulfate precipitation, 70% ammonium sulfate precipitation, phenyl-Sepharose chromatography, Mono Q column chromatography, DEAE-cellulose column chromatography, or tetrahydromethanopterin affinity column chromatography. Methylreductase preparations which were able to catalyze methanogenesis in the simplified reaction mixture contained contaminating proteins. Homogeneous component C obtained from a tetrahydromethanopterin affinity column was not active in the simplified assay but was active in a methylreductase assay that contained additional protein components.     

A map of barley chromosome 2 using isozymic and morphological markers

The F₂ progeny of a cross between a chromosome 2 multiple marker stock and an adapted cultivar of barley were analyzed for four morphological markers and electrophoretic patterns of eight leaf isozymes. TheIdh-2 locus was linked to thePer-5 locus (27.96±5.07 cM) and to thee locus (10.26±3.13 cM). Also, thePer-5 ande loci were located on the short arm of chromosome 2. In additionIdh-2 was also located on barley chromosome 2 and was linked to thev locus (13.18±3.56 cM), which is located on the long arm of chromosome 2. Two other marker genes,li andwst,,B, were linked (26.50±5.24 cM) on chromosome 2 but segregate independently of the other loci evaluated. This project was supported by funds from the U.S.-Spain Joint Committee for Scientific and Technological Cooperation.     

Indoxyl-beta-D-glucuronide, a novel chromogenic reagent for the specific detection and enumeration of Escherichia coli in environmental samples

About 97% of Escherichia coli strains produce beta-glucuronidase, but almost all other Enterobacteriaceae lack this enzyme. A D-glucopyranosiduronic acid (glucuronide) possessing a readily detectable beta-linked aglycone should, therefore, constitute a specific reagent for the detection of this organism. For this purpose, the title compound has been synthesized for the first time. The synthesis proceeds in eight steps from readily available D-glucuronolactone, anthranilic acid, and chloroacetic acid and can be carried out on a large scale. The compound has the predicted properties: when included in the standard membrane filter test for the analysis of water, indoxyl-beta-D-glucuronide allows specific detection of E. coli through the formation of blue colonies that are the result of rapid conversion of the liberated aglycone to indigo. The recovery of E. coli is easily measured and almost quantitative.     

In situ hybridization methods for the detection of somatostatin mRNA in tissue sections using antisense RNA probes

In situ hybridization studies with [32P] and [3H] labelled antisense RNA probes were undertaken to determine optimal methods of tissue fixation, tissue sectioning, and conditions of hybridization, and to compare the relative merits of the two different radioactive labels. The distribution of somatostatin mRNA in neurons of rat brain using a labelled antisense somatostatin RNA probe was employed as a model for these studies. The highest degree of sensitivity for in situ hybridization was obtained using paraformaldehyde fixation and vibratome sectioning. Optimal autoradiographic localization of mRNA was obtained within 7 days using [32P] labelled probes. However, due to the high energy emittance of [32P], precise intracellular localization of hybridization sites was not possible. [3H] labelled RNA probes gave more precise cellular localization but required an average of 18-20 days autoradiographic exposure. The addition of the scintillator, PPO, decreased the exposure time for the localization of [3H] labelled probes to seven days. We also report a method for combined in situ hybridization and immunocytochemistry for the simultaneous localization of somatostatin in mRNA and peptide in individual neurons.     

Improved Agar Bottle Plate for Isolation of Methanogens or Other Anaerobes in a Defined Gas Atmosphere

A bottle plate for the cultivation of methanogens or other organisms in a defined pressurized-gas atmosphere was developed. The bottle provides the convenience of an agar streak plate, solves the problem of the water exudate from agar medium, and provides a convenient way of adding or sampling a defined gas atmosphere.     

Polyamine-phospholipid interaction probed by the accessibility of the phospholipidsn-2 ester bond to the action of phospholipase A2

Summary Conditions were used where the action of porcine pancreatic phospholipase A2 on phospholipids can be followed in the absence of added calcium and the catalytic activity is supported by the calcium brought with the nanomolar enzyme. Therefore, alterations in the enzyme velocity resulting from the presence of spermine or spermidine could be specifically studied using 1-palmitoyl-2-(pyren-1-yl)hexanoyl-sn-glycero-3-phosphocholine (PPHPC) and 1-palmitoyl-2-(pyren-1-yl)hexanoyl-sn-glycero-3-phosphoglycerol (PPHPG) as substrates. Both spermine and spermidine activated the hydrolysis of PPHPG fourfold at polyamine/phospholipid molar ratios of approximately 11 and 121, respectively. Double-reciprocal plots of enzyme activityvs. PPHPG concentration revealed the enhancement to be due to increased apparentV _max while the apparentK _m was slightly increased. In the presence of 4mm CaCl₂ inhibition by polyamines of PPHPG hydrolysis by phospholipase A2 was observed. Using synthetic diamines we could further demonstrate that two primary amino groups are required for the activation. In the absence of exogenous CaCl₂ polyamines inhibited the hydrolysis of PPHPC by phospholipase A2. The presence of 4mm CaCl₂ reversed this inhibition and a twofold activation was observed at 10 m spermine. The results obtained indicate that the activation of PLA2 by spermine and spermidine is produced at the level of the substrate, PPHPG. This implies the formation of complexes of phosphatidylglycerol and polyamines with defined stoichiometries.     

Evidence for H-2-linked control of retrovirus production in Friend virus-induced tumor cell lines.

In Friend leukemia virus-induced tumor cell lines derived from mice congenic with respect to the H-2 complex, most cell lines expressing the H-2k haplotype continuously produced infectious exogenous virus in culture, whereas most cell lines expressing the H-2b or H-2d haplotype stopped producing virus during in vitro passage. This apparent H-2-linked control of virus production did not appear to be the result of alteration of the provirus or resistance to superinfection. The implications of this finding with respect to virus-induced leukemogenesis are discussed.     

Ammonium repression of cephalosporin production by Streptomyces clavuligerus

Production of beta-lactam antibiotics took place during growth of Streptomyces clavulgerus in chemically defined medium. The specific activities of isopenicillin N synthetase ("cyclase"), isopenicillin N epimerase, and deacetoxycephalosporin C synthetase ("expandase") increased during the exponential phase of growth. Specific cephalosporin productivity during fermentation followed a similar pattern, reaching a maximum near the end of the growth phase and decaying rapidly in the stationary phase. Ammonium chloride depressed cephalosporin production, presumably as a result of repression of cyclase and expandase formation, but not of epimerase. No inhibitory effects on enzyme activity by ammonium were found. Addition of tribasic magnesium phosphate [Mg3(PO4)2 X 8H2O] prevented the repression of cyclase and markedly stimulated cephalosporin production. Cephamycin C and, in smaller amounts, O-carbamoyldeacetylcephalosporin C were the only cephalosporins detected. Growth with ammonium resulted in lower titers of both compounds, and did not change the relative proportion of each. The correlation found between cephalosporin productivity and cyclase specific activity in different media suggests that formation of this enzyme may be the rate-limiting step in the pathway.