Aggregation of synthetic metallochlorins in hexane. A model of chlorosomal bacteriochlorophyll self-assemblies in green bacteria

Metal 3¹-hydroxy-13¹-oxo-chlorins were systematically prepared and their visible and circular dichroism spectra were measured in a solution. All the synthetic complexes were monomeric in tetrahydrofuran. The Ni/Cu/Pd/Ag(II) complexes were still monomeric after dilution with 99-fold hexane. In contrast, the Co(II) complex, as well as the Mg/Zn/Cd(II) complexes, self-aggregated in 1% (v/v) tetrahydrofuran-hexane to form oligomers. In the less polar organic solvent, the Mn(III) complex fully dimerized and the Fe(III) complex partially dimerized. Infrared spectra of the synthetic metal chlorins in solid thin films revealed that the Ni/Cu/Pd/Ag(II) and ClFe(III) chlorins were 4- and 5-coordinated monomers, respectively, the AcOMn(III) chlorin formed a 6-coordinated dimer by mutual coordination of 3¹-OMn, and the Co(II) chlorin as well as the Mg/Zn/Cd(II) chlorins self-aggregated by 13-C=OO-Hmetal to form large oligomers.This revised version was published online in October 2005 with corrections to the Cover Date.     

Molecular motion of small nonelectrolyte molecules in lecithin bilayers

Summary We have used magnetic resonance spectroscopy, both ESR and¹³C spin relaxation, to measure translational and rotational mobilities and partition coefficients of small nitroxide solutes in dipalmitoyl lecithin liposomes. Above the bilayer transition temperature,T _c, the bilayer interior is quite fluid, as determined from the solutes' rapid rotational and moderately rapid translational motion; the rotational and translational viscosities within the bilayer are _R <1cP and =6–10cP, respectively. and _R are independent of molecular size for all solutes studied, but all were small compared to the size of the phospholipids. , and probably _R , are relatively independent of temperature aboveT _c, but both increase very sharply as temperature is lowered belowT _c; at 32°C, _R increases to 6cP and is greater than 1000 cP. Anisotropy of rotational motion increases gradually as temperature is lowered toT _c, and changes little belowT _c; anisotropy of translational motion was not investigated.¹³C nuclear spin relaxation measurements indicate that translational motion of nitroxide solutes is more rapid in the center of the bilayer than near the polar interface. It takes at least 100 nsec for a solute molecule to cross the bilayer/water interface. We estimate a lower limit of 2 sec/cm for the interfacial resistance to solute diffusion; this result indicates that interfacial resistance dominates permeation across the membrane. The relative solubility, or partition coefficient, is a strong function of solute structure, and decreases abruptly on cooling through the transition temperature. From the partition coefficient and its temperature dependence we calculate the free energy, enthalpy, and entropy of partition. Effects of cholesterol on partition and diffusion coefficients are compatible with the interpretation that bilayers containing cholesterol consist of two phases.     

Contextualizing Images in Dreams and Daydreams

A contextualizing image (CI) is a powerful central image of a dream which appears to contextualize (provide a picture-context for) the dreamer's emotion. For instance, dreamers who have experienced any serious traumatic event sometimes dream, I was overwhelmed by a tidal wave. This appears to picture their feeling of terror and/or vulnerability.A scoring system for CIs is examined here and is applied to dreams and daydreams supplied by 40 students. Two raters scoring dreams on a blind basis showed good inter-rater reliability. Recent dreams were shown to have more as well as more intense CIs than recent daydreams; likewise, dreams that stand out had more intense CIs than daydreams that stand out. Students with thin boundaries had more and more intense CIs than students with thick boundaries in their recent dreams and nightmare, but not so clearly in dreams and nightmares that stand out. The emotions judged as contextualized by the powerful images tended towards fear/terror and helplessness/vulnerability in dreams (especially in dreams that stand out) whereas emotions contextualized by images in daydreams showed a wide range with no clusters.     

Lipase-mediated homotopic and heterotopic double resolutions of a planar chiral organometallic alcohol

Summary (±)-Tricarbonyl ⁶-3-methylbenzyl alcohol)chromium was resolved to of 100%e.e. and of 92%e.e. by lipase-catalyzed transesterifications arranged in homotopic and heterotopic double resolutions.     

Uptake of bacteriophage λ DNA in Escherichia coli by electroporation: An alternative to in vitro packaging

Summary By using a high field strength DC pulse of 15 kV/cm and a pulse duration of 5 ms for the transfection of E. coli by bacteriophage DNA, we obtained efficiencies of 1.1 × 10⁶ (pfu/g bacteriophage , DNA). This represents a 100-fold improvement over the traditional CaCl₂/heat shock method and is a viable alternative to the more costly in vitro packaging of recombinant bacteriophage DNA for the production of cDNA and genomic libraries.     

Kinetics of growth and lactic acid production in continuous and batch culture

Summary In a lactic acid fermentation by Streptococcus faecalis, the specific consumption rate of glucose (v) and the specific production rate of lactic acid () were represented by the following simple equations as functions of the specific growth rate (): 1/=(1/) + 1/ = (1/) + By use of data from a batch culture, these two equations were derived from enzyme kinetics of the product inhibition. These equations were successfully applied to the results of batch culture and chemostat culture. In addition, calculation of ATP yield by these equations agreed with the experimental results better than the conventional Leudeking-Piret type equation, which includes two terms associated with growth and not with growth. Correspondence to: H. Ohara     

Purification and properties of a lambda operator-binding protein which is expected to be autorepressor (tof protein) from E. coli carrying lambdadv plasmid.

Summary In order to study the mode of action of the tof gene product, which is an autorepressor of the bacteriophage and plasmid dv, we have purified a DNA-binding protein which is specifically produced in bacteria carrying dv. This protein possesses characteristics expected for the product of the tof gene, since it is produced under conditions where cI-repressor is not made, and since it binds to oL and oR operators on the phage genome. The molecular weight of the native protein is 16,000–17,000 daltons, and the monomeric molecular weight as measured by gel electrophoresis in the presence of sodium dodecyl sulfate is about 10,000 daltons. Denaturation and renaturation experiments demonstrated that the native protein is a dimer of 10,000-dalton monomers. The DNA-specific binding protein is not produced in cells carrying i ²¹dv or 80dv.     

Die Intravitale Karyorrhexis Der Exokrinen Pankreaszelle im Elektronenmikroskopischen Bild

Zusammenfassung Die intravitale Karyorrhexig wird am exokrinen Pankreas der Maus nach Osmium- und Formalinfixierung licht- und elektronenmikroskopisch untersucht. Im Verlaufe der Karyorrhexis kommt es zu einer Trennung des Karyoplasmas in 'Chromatin und 'Karyolymphe (Interchromatin-Substanz). In fortgeschrittenen Stadien ist das Bild solcher Zellkerne — im Gegensatz zu normalen Intermitosekernen — nach beiden Fixierungsmethoden fast identisch. Das Chromatin ist in dichten, membranständigen Kappen konzentriert. Der übrige Kernraum wird — abgesehen vom Nukleolus — von der hellen Karyolymphe ausgefüllt. In ihrem Bereich treten die sog. Interchromatingranula (200–250 Å), einzeln oder in dichten Haufen, meist deutlich hervor. Der Nukleolus, dessen Feinstruktur nicht auffallend verändert ist, liegt entweder frei oder den Chromatinkappen unmittelbar an. Die Kernhülle ist bei fortgeschrittener Karyoplasmaentmischung unversehrt oder über kürzere oder längere Strecken geschwunden. Im Endstadium der Karyorrhexis sind mehrere, von Kernmembranfragmenten unvollständig begrenzte Chromatinbrocken wahllos im Zelleib verstreut. Die cytoplasmatischen Strukturen können auch bei ausgeprägten Kernveränderungen noch weitgehend normal aussehen.Die karyorrhektischen Kernveränderungen werden als Folge einer 'Entmischung des Karyoplasmas gedeutet, für die eine Dehydratation der DNS-tragenden Chromosomenstrukturen verantwortlich gemacht wird. Auch das Sichtbarwerden und das Verklumpen der 'Interchromatingranula wird auf eine Dehydratation zurückgeführt.

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Summary The intravital caryorrhexis in the exocrine pancreas of the mouse was studied by means of light- and electron microscopy after fixation with osmium and formaldehyde. During caryorrhexis the caryoplasm segregates into chromatin and caryolymphe (interchromatinic substance). In contrast to normal intermitotic nuclei both fixations result in a very similar picture of the typical caryorrhectic nuclei. The chromatin is concentrated in dense caps associated with the nuclear envelope. Except those dense caps and apart from the nucleolus the whole nucleus is occupied by the light caryolymphe. In this area the so-called interchromatinic granules (200–250 Å) become clearly visible, isolated or in dense clumps. The nucleolus, the fine structure of which has not remarkably changed, can be found either isolated or in touch with the chromatin caps. During advanced segregation of the caryoplasm the nuclear envelope was found to be either unimpaired or had disappeared for variable lenghths. In the final stage of caryorrhexis several chromatin clumps — partly confined by fragments of the nuclear envelope — are distributed irregularly within the cell. Even in the case of pronounced nuclear changes the cytoplasmic structures may appear almost unaffected.It is assumed that the nuclear changes during caryorrhexis are due to a segregation of the caryoplasm, caused by dehydration of the DNA-carrying chromosome fibrils. Also dehydration is made responsible for the appearance and clumping of the interchromatinic granules.

     

Synthesis of alkyl β-glucosides from cellobiose with Aspergillus niger β-glucosidase II

An extracellular -glucosidase II of Aspergillus niger catalyzed the synthesis of methyl -glucoside and ethyl -glucoside with 5.0% (v/v) cellobiose as glucosyl donor in a biphasic media containing 20% (v/v) methanol and 30% (v/v) ethanol, respectively. The maximum yield of methyl -glucoside and ethyl -glucoside was 83% (mol/mol; 12 mg/ ml) and 53% (mol/mol; 5.5 mg/ml), based on cellobiose consumed. © Rapid Science Ltd. 1998     

Repressor and rex product of coliphage lambda: lack of collaboration and joint controls

Summary Exposure to 41° C for 10 to 100 minutes rapidly inactivates repressor bearing several ts mutations in the A or B region of gene cI, but does not result in simultaneous rapid loss of the rex function, which restricts phage T4 rII. One may conclude that the rex product does not directly collaborate with the repressor protein. Immediate loss of the rex activity at 47.5° C, observed with most of the cIts mutants and even cI⁺, appears to be unrelated to the repressor inactivation. In tof ⁺ lysogens carrying nonlethal cIts prophage mutants, the prolongation of induction at 41° C ultimately results in irreversible loss of the rex function, but only after about six cell generations. In similar experiments with tof deficient lysogens, loss of the rex activity requires about eleven cell generations and the rex function is regained in less than 30 minutes after return of the lysogen to 30° C. Two methods of rex assay, the more sensitive phage yield method and the infective center method, were employed.     

Generalized recombination in tandem duplications of bacteriophage lambda

Summary Recombination between the tandem duplicated segments of b221a106-15 yields unduplicated (single-copy) b221 phage. The apparent frequency of intramolecular events among these recombinations was determined for both cellular (Rec) and bacteriophage (Red) generalized recombination systems. The progeny from single-cycle growth experiments with genetically marked duplication phages were treated with EDTA to inactivate all but the singlecopy phages produced by recombination. Analysis of the genotypes of the EDTA-resistant phages suggested that intramolecular events were about 1 to 5 times as frequent as intermolecular ones. While the results suggest that intramolecular events are not intrinsically forbidden, the quantitative values for the ratio depend on the assumption that intracellular phage chromosomes are completely mixed.     

Comparative residual toxicities of pesticides to the predator Agistemus industani (Acari: Stigmaeidae) on citrus in Florida

Residual toxicities of registered and selected experimental pesticides used on citrus against Agistemus industani Gonzalez (Acari: Stigmaeidae) were compared. Pesticides considered highly toxic to A. industani were: abamectin 0.15 EC at 731ml/ha+FC 435-66 petroleum oil at 46.8l/ha, pyridaben 75WP at 469g/ha, ethion 4EC at 7.01l/ha+FC 435-66 petroleum oil at 46.8l/ha, propargite 6.55 EC at 3.51l/ha, chlorfenapyr 2SC at 1.46l/ha applied alone or in combination with FC 435-66 petroleum oil at 46.8l/ha, sulphur 80DF at 16.81kg/ha, dicofol 4EC at 7.01l/ha, fenbutatin oxide 50WP at 2.24kg/ha, benomyl 50WP at 2.24kg/ha, benomyl 50WP at 1.68kg/ha+ferbam 76 GF at 5.60kg/ha, ferbam 76GF at 11.21kg/ha, neem oil 90EC at 46.8l/ha, and copper hydroxide DF (40% metallic copper) at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha. Pesticides that were moderately to slightly toxic included: copper sulphate 98% at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha, fenbuconazole 2F at 280ml/ha+FC 435-66 petroleum oil at 46.8l/ha, FC 435-66 petroleum oil applied alone at 46.8l/ha or 23.4l/ha, and diflubenzuron 25WP at 1.40kg/ha. Pesticides that were non-toxic included: fenbuconazole 2F at 585ml/ha, malathion 57EC at 5.85l/ha, FC 435-66 petroleum oil at 46.8l/ha, carbaryl 80S at 3.36kg/ha, chlorpyrifos 4EC at 4.68l/ha, and formetanate 92SP at 1.12kg/ha. Understanding the toxic effects of field weathered pesticides against key predacious mite species is important for effective IPM. The results of this study provide a comparison of direct and indirect toxic effects of various pesticides to A. industani under field conditions.     

Polymerization of β-amino Acids in Aqueous Solution

We have compared carbonyl diimidazole (CDI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as activating agents for the oligomerization of negatively-charged - and -amino acids in homogeneous aqueous solution. -Amino acids can be oligomerized efficiently using CDI, but not by EDAC. -Amino acids can be oligomerized efficiently using EDAC, but not by CDI. Aspartic acid, an - and -dicarboxylic acid is oligomerized efficiently by both reagents. These results are explained in terms of the mechanisms of the reactions, and their relevance to prebiotic chemistry is discussed.     

Dependence of transfection efficiency of calcium treated Escherichia coli cells on bacterial genotype and form of lambda DNA

Summary The transfecting activity of linear DNA is 100 times higher in calcium treated E. coli K 12 (ⁱ⁴³⁴) than in non-lysogenic strains: the levels of transfection are 1–2.10⁷ and 1–2.10⁵ infective centers per 1 g of DNA, respectively. The high efficiency of lysogenic cells transfection is not due to the spontaneously liberated helper phage. Evidently, it is called forth by transfecting DNA-prophage recombination or/and by inhibition of nuclease activity in lysogenic cells. Both ring forms DNA (supercoiled and open circles) show very low infectivity, if any, in calcinated cells.     

Residual motion of hemoglobin-bound spin labels and protein dynamics: viscosity dependence of the rotational correlation times

The residual motion of spin labels bound to cysteine 93 and to lysines of methemoglobin has been studied by electron paramagnetic resonance spectroscopy. To separate the influences of the solvent and the protein environment of the label fluctuations, the correlation times, , were analyzed as a function of temperature for fixed solvent viscosities, . Results show that over a wide range of viscosity the dependence of on may be empirically described by a power law ^k . The exponent k depends strongly on the location of the label on the protein surface. If one regards the spin labels as artificial amino acid side chains, characteristic values of correlation times and amplitudes of the rotational motion at the surface can be given. For =1 cP and T=297 K the correlation time of the labels bound to lysines is found to be =9 · 10^–10 s and the rotational diffusion is nearly isotropic. The spin label bound to cysteine 93 occupies a protein pocket, its rotational motion is therefore restricted. The correlation time of the label motion within a limited motion cone of semi angle =30° ± 3° is found to be =1.3 · 10^–9 s for =1 cP and T=297 K.     

A mutation in Escherichia coli enhancing the UV-mutability of phage lambda but not of its infectious DNA in a spheroplast assay

Summary A mutant (called mul) has been isolated from E. coli AB1157 which increases up to 13 fold the rate of clear plaque mutations of extracellularly UV-irradiated phage . The mul-mutation does not affect the UV-mutability of T4rII mutants or various bacterial markers and therefore seems to act specifically on UV-irradiated phage . However, when spheroplasts prepared from mul cells were infected with either irradiated or unirradiated -DNA equal frequencies of clear plaques were produced. As there is indirect evidence (host cell reactivation) that the spheroplasts do not significantly exclude irradiated phage DNA it seems that the mul phenotype can be expressed only in complete cells.The mutation responsible for the mul phenotype has been mapped by conjugation and transduction to be located between the markers pyrE and ilv and probably marks a new gene. The mul mutation does not increase the UV-sensitivity of the cells nor does it affect their ability to perform host cell reactivation. The presence of a recA allel in a mul mutant abolishes the UV-mutability of phage .Part of this work is from the thesis of the first author in partial fullfilment of the requirements for the doctoral degree of the University of Bochum. Some of the results have already been presented at the 32. Kongreß für Hygiene und Mikrobiologie at Münster, 1969.     

Inactivation of voltage-dependent calcium current in an insulinoma cell line

We have studied the mechanism of Ca current inactivation in the -cell line HIT-T15 by conventional and perforated patch recording techniques, using two pulse voltage protocols and a combination of current and tail current measurements. In 5 mM Ca, from a holding potential of - 80 mV, the maximum current showed a complex time course of inactivation: a relatively fast, double exponential inactivation (_h1 12 ms and _h2 60 ms) and a very slowly inactivating component ( > 1 s). The faster component (_h1) was due to the voltage-dependent inactivation of a low-threshold-activated (LVA), T-type current, which deactivates more slowly ( 3–5 ms) than the other components ( 0.2–0.3 ms). The intermediate component (_h2) was due to the Ca-dependent inactivation of a portion of the high-threshold-activated (HVA) current. A saturating dose of the dihydropyridine (DHP) nifedipine (10 M) did not affect the LVA current, but inhibited by 68 ± 5% the transient, Ca-sensitive portion of the HVA current and by 33 ± 12% the long lasting component. We suggest that three components of the calcium current can be resolved in HIT cells and the main target of DHPs is a HVA current, which inactivates faster than the DHP-resistant HVA component and does so primarily through calcium influx. Correspondence to: C. Marchetti     

Cloning of the dnaB gene of Escherichia coli: the dnaB gene of groPB534 and groPB612 and the replication of phage lambda

Summary Fragments of the E. coli chromosome that carry the dnaB groPB534 or groPB612 alleles have been cloned into a cosmid vector. The resulting recombinant plasmids contained the genes uvrA, groP (B534 or B612), and lexA. Further subcloning into high copy number plasmids, during which the uvrA and lexA genes were removed successively, yielded a groPB534 and groPB612 DNA fragment of about 2.4 kb each. Both fragments contained an overlapping 1.8 kb segment of DNA in which the sites of all restriction enzymes tested were identical. The size of these dnaB gene fragments were further delimited by deletion analysis.In E. coli groPB534 in which wild-type and A mutants do not replicate (Georgopoulos and Herskowitz 1971) phage replication is rescued if the strain contains the groPB534 gene on high copy number plasmids. On the contrary, in E. coli groPB612, which is temperature-sensitive for its groP character, replication of and A is abolished at 30° C if the strain contains the groPB612 recombinant plasmid. On the other hand, replication of B remains unaffected whether or not the groP strains harbor the isogenic dnaB gene-containing plasmid. The results suggest that within the cell not only the quality but also the relative amounts of dnaB and P protein are crucial for phage replication.     

Characterization of three novel members of the Arabidopsis SHAGGY-related protein kinase (ASK) multigene family

In this paper we report the characterization of three novel members of the Arabidopsis shaggy-related protein kinase (ASK) multigene family, named ASKdzeta (ASK), ASKetha (ASK) and ASKiota (ASK). The proteins encoded by the ASK genes share a highly conserved catalytic protein kinase domain and show about 70% identity to SHAGGY (SGG) and glycogen synthase kinase-3 (GSK-3) from Drosophila and rat respectively. SGG is an ubiquitous intracellular component of the wingless signalling pathway that establishes cell fate and/or pattern formation in Drosophila. At least ten different ASK genes are expected to be present per haploid genome of A. thaliana. Different amino- and carboxy-terminal extensions distinguish different ASK family members. Five ASK gene sequences were analysed and shown to be present as single-copy genes in the Arabidopsis genome. A comparison based on the highly conserved catalytic domain sequences of all known sequences of the GSK-3 subfamily of protein kinases demonstrated a clear distinction between the plant and the animal kinases. Furthermore, we established the presence of at least three distinct groups of plant homologues of SGG/GSK-3. These different groups probably reflect biochemical and/or biological properties of these kinases. The differential expression patterns of five ASK genes were accessed by northern and in situ hybridization experiments using gene-specific probes. While ASK is expressed in the whole embryo during its development, ASK expression is limited to the suspensor cells. No signal was detected for ASK, ASK and ASK in developing embryos.