The degradation of distance discrimination in big brown bats (Eptesicus fuscus) caused by different interference signals

The ability of two big brown bats (Eptesicus fuscus) to discriminate the distance to an electronically synthesized phantom target by echolocation was tested in the presence of interfering signals presented slightly before the target echo. Interfering signals were chosen to have differing degrees of similarity to the typical echolocation emission used by the bat in this task (which was the signal used to create the phantom target), and we predicted that the degree of disruption of ranging would be proportional to the similarity of the interference to the target echo. This prediction was not confirmed; rather, all interference signals not identical to the target echo increased the threshold to about twice that found with no interference. When the interference was identical to the target echo, the threshold increased to about 4 times that with no interference. When each bat was presented with phantom target echoes appropriate for the other bat, its range discrimination threshold increased about ten fold, and in this case the degree of interference of different signals was related to their similarity to the target echo, not to their similarity to the bat's normal signal. We suggest that Eptesicus may suppress interference by a more sophisticated strategy than simple linear matched filtering.Abbreviations E exemplar signal - M _f foreign model signal - M _r reversed self-model signal - M _s self-model signal - N noise signal - SPL sound pressure level     

Comparative mapping in F2∶3 and F6∶7 generations of quantitative trait loci for grain yield and yield components in maize

This study was conducted to compare maize quantitative trait loci (QTL) detection for grain yield and yield components in F₂₃ and F₆₇ recombinant inbred (RI) lines from the same population. One hundred and eighty-six F₆₇ RIs from a Mo17×H99 population were grown in a replicated field experiment and analyzed at 101 loci detected by restriction fragment length polymorphisms (RFLPs). Single-factor analysis of variance was conducted for each locus-trait combination to identify QTL. For grain yield, 6 QTL were detected accounting for 22% of the phenotypic variation. A total of 63 QTL were identified for the seven grain yield components with alleles from both parents contributing to increased trait values. Several genetic regions were associated with more than one trait, indicating possible linked and/or pleiotropic effects. In a comparison with 150 F₂₃ lines from the same population, the same genetic regions and parental effects were detected across generations despite being evaluated under diverse environmental conditions. Some of the QTL detected in the F₂₃ seem to be dissected into multiple, linked QTL in the F₆₇ generation, indicating better genetic resolution for QTL detection with RIs. Also, genetic effects at QTL are smaller in the F₆₇ generation for all traits.Abbreviations RFLPs Restriction fragment length polymorphisms - QTL quantitative trait loci - RIs recombinant inbreds Journal Paper no. J-16261 of the Iowa Agric and Home Economics Exp Stn Project no. 3134     

Comparison of the carbohydrate moieties of recombinant soluble Fcε receptor (sFcε RII/sCD23) expressed inSaccharomyces cerevisiae and Chinese hamster ovary cells. Different O-glycosylation sites are used by yeast and mammalian cells

Recombinant human soluble low affinity receptor for the Fc portion of IgE (sFcRII/sCD23) was produced inSaccharomyces cerevisiae or Chinese hamster ovary cells and subjected to carbohydrate analysis. Applied methods included analytical SDS-PAGE, reversed phase HPLC, methylation analysis and sequential degradation with exoglycosidases. The results revealed that sFcRII derived from Chinese hamster ovary cells is glycosylated exclusively at Ser-147, containing mainly the trisaccharide Sia(2–3)Gal(1–3)GalNAc, whereas the yeast derived glycoprotein was glycosylated at Ser-167 and contained only -mannosyl residues. It is shown here for the first time that different amino acids of a given protein can be O-glycosylated when expressed in yeast or Chinese hamster ovary cells.     

Integration time for short broad band clicks in echolocating FM-bats (Eptesicus fuscus)

Vespertilionid FM-bats (four Eptesicus fuscus and one Vespertilio murinus) were trained in an electronic phantom target simulator to detect synthetic echoes consisting of either one or two clicks. The threshold sound pressure for single clicks was around 47 dB peSPL for all five bats corresponding to a threshold energy of -95 dB re 1 Pa² * s. By varying the interclick interval, T, for double clicks it was shown that the threshold intensity was around — 3 dB relative to the threshold for single clicks at T up to 2.4 ms, indicating perfect power summation of both clicks. A threshold shift of -13.5 dB for a 1 ms train of 20 clicks (0.05 ms interclick interval) confirmed that the bats integrated the power of the stimuli. At T longer than around 2.5 ms the threshold for double clicks was the same as for single clicks. Thus, the bats performed like perfect energy detectors with an integration time of approximately 2.4 ms. This integration time is an order of magnitude shorter than that reported for bats listening passively for pure tones. In our setup the bats emitted sonar signals with durations of 2–3 ms. Hence, the results may indicate that while echolocating the bats integration time is adapted to the duration of the sonar emissions.Abbreviations AGC automatic gain control - FM frequency modulated - peSPL peak equivalent sound pressure level - rms root mean square - SD standard deviation - SE standard error of mean - T interclick interval     

Absorbance difference spectra of the S-state transitions in Photosystem II core particles

Redox changes of the oxygen evolving complex in PS II core particles were investigated by absorbance difference spectroscopy in the UV-region. The oscillation of the absorbance changes induced by a series of saturating flashes could not be explained by the minimal Kok model (Kok et al. 1970) consisting of a 4-step redox cycle, S₀ S₁ S₂ S₃ S₀, although the values of most of the relevant parameters had been determined experimentally. Additional assumptions which allow a consistent fit of all data are a slow equilibration of the S₃ state with an inactive state, perhaps related to Ca²⁺-release, and a low quantum efficiency for the first turnover after dark-adaptation. Difference spectra of the successive S-state transitions were determined. At wavelengths above 370 nm, they were very different due to the different contribution of a Chl bandshift in each spectrum. At shorter wavelengths, the S₁ S₂ transition showed a difference spectrum similar to that reported by Dekker et al. 1984b and attributed to an Mn(III) to Mn(IV) oxidation. The spectrum of absorbance changes associated with the S₂ S₃ transition was similar to that reported by Lavergne 1991 for PS II membranes. The S₀ S₁ transition was associated with a smaller but still substantial absorbance increase in the UV. Differences with the spectra reported by Lavergne 1991 are attributed to electrostatic effects on electron transfer at the acceptor side associated with the S-state dependence of proton release in PS II membranes.Abbreviations Bis-Tris (bis[2-hydroxyethyl]imino-tris[hydroxymethyl]methane) - DCBQ 2,5-dichloro-p-benzoquinone - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - PS II Photosystem II - Q_A secondary electron acceptor of PS II - S₀ to S₄ redox state of the oxygen evolving complex - Z secondary electron donor of PS II     

Preparation of a series of sulfated tetrasaccharides from shark cartilage chondroitin sulfate D using testicular hyaluronidase and structure determination by 500 MHz1H NMR spectroscopy

Six tetrasaccharide fractions were isolated from shark cartilage chondroitin sulfate D by gel filtration chromatography followed by HPLC on an amine-bound silica column after exhaustive digestion with testicular hyaluronidase. Their structures were determined unambiguously by one- and two-dimensional 500 MHz¹H NMR spectroscopy in conjunction with HPLC analysis of chondroitinase AC-II digests of the tetrasaccharides. One fraction was found to contain two tetrasaccharide components. All the seven tetrasaccharides shared the common core structure GlcA1-3GalNAc1-4GlcA1-3GalNAc with various sulfation profiles. Four were disulfated comprising of two monosulfated disaccharide units GlcA1-3GalNAc(4-sulfate) and/or GlcA1-3GalNAc(6-sulfate), whereas the other three were hitherto unreported trisulfated tetrasaccharides containing a disulfated disaccharide unit GlcA(2-sulfate)1-3GalNAc(6-sulfate) and a monosulfated disaccharide unit GlcA1-3GalNAc(4-or 6-sulfate). These sulfated tetrasaccharides were demonstrated to serve as appropriate acceptor substrates for serum -N-acetylgalactosaminyltransferase, indicating their usefulness as authentic oligosaccharide substrates or probes for the glycobiology of sulfated glycosaminoglycans.Abbreviations NFU National formulary unit - COSY correlation spectroscopy - HOHAHA homonuclear Hartmann-Hahn - 1D or 2D one- or two-dimensional - IdoA l-iduronic acid - GlcA d-gluco-4-enepyranosyluronic acid - Di-0S GlcA1-3GalNAc - Di-4S GlcA1-3GalNAc(4-sulfate) - Di-4S GlcA1-3GalNAc(4-sulfate) - Di-6S GlcA1-3GalNAc(6-sulfate) - Di-6S GlcA1-3GalNAc(6-sulfate) - Di-diS _d GlcA(2-sulfate)1-3GalNAc(6-sulfate) - Di-diS_E GlcA1-3GalNAc(4, 6-disulfate) - U G, U, 2S, 4S, and 6S represent GlcA, GalNAc, GlcA, 2-O-sulfate, 4-O-sulfate, and 6-O-sulfate, respectively     

Adoptions expérimentales de larves entre des fourmis de genres différents (II):Myrmica laevinodis Nylander etAnergates atratulus Schenck

Résumé Nous avons fait élever des larves d'Anergates atratulus par des ouvrières deMyrmica laevinodis à 22°C. Pour y parvenir, il n'est pas utile de faire hivernerensemble les larves d'Anergates et les ouvrières deMyrmica. La présence de larves autochtones n'empêche pas lesMyrmica d'élever des larves d'Anergates. Dans toutes les expériences lesMyrmica ont été soumises au fridavant de recevoir des larves d'Anergates. Aucune reine deMyrmica n'a été utilisée dans ces expériences.Sur les 64 larves d'Anergates que nous avons utilisées, 38 se sont transformées en imagos. C'est au début de l'adoption et au moment des métamorphoses que périrent la plupart des 26Anergates perdus. Les femelles vécurent en général 2 ou 3 jours et cherchèrent très tôt à quitter le nid natal. Les mâles vécurent 2 à 3 semaines.

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Summary Larvae ofAnergates atratulus were experimentally reared by workers ofMyrmica laevinodis, at 22°C. An overwintering of both larvae ofAnergates and workers ofMyrmica is not necessary for the success of that experiment. The presence of larvae ofMyrmica does not keep theMyrmica from rearing larvae ofAnergates. The workers ofMyrmica have been cooled, in all the experiments, before receiving larvae ofAnergates. No queen ofMyrmica have been used in that experiments.38 of the 64 larvae ofAnergates used became imagos. Most of the 26 lostAnergates died at the beginning of the adoption and during the metamorphosis. The females lived generally 2 or 3 days and tried, very early, to leave their native nest. The males lived 2 or 3 weeks.

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Anergates atratulus Myrmica laevinodis, 22 . bmecme Anergates Myrmica. Myrmica Anergates. Myrmica Anergates. Myrmica . 64 Anergates , 38 . 26 Anergates 2 3 . 2 3 .

     

Selectively 13C-enriched DNA: Evidence from 13C1′ relaxation rate measurements of an internal dynamics sequence effect in the lac operator

Summary In order to study some internal dynamic processes of the lac operator sequence, the ¹³C-labeled duplex 5d(C₀G₁C₂T₃C₄A₅C₆A₇A₈T₉T₁₀) · d(A₁₀A₉T₈T₇G₆T₅G₄A₃G₂C₁G₀)3 was used. The spreading of both the H1 and C1 resonances brought about an excellent dispersion of the ¹H1-¹³C1 correlations. The spinlattice relaxation parameters R(C_z), R(C_x,y) and R(H_zC_z) were measured for each residue of the two complementary strands, except for the 3-terminal residues which were not labeled. Variation of the relaxation rates was found along the sequence. These data were analyzed in the context of the model-free formalism proposed by Lipari and Szabo [(1982) J. Am. Chem. Soc., 104, 4546–4570] and extended to three parameters by Clore et al. [(1990) Biochemistry, 29, 7387–7401; and (1990) J. Am. Chem. Soc., 112, 4989–4991]. A careful analysis using a least-squares program showed that our data must be interpreted in terms of a three-parameter spectral density function. With this approach, the global correlation time was found to be the same for each residue. All the C1-H1 fragments exhibited both slow (_s = 1.5) and fast (_f = 20 ps) restricted libration motions (S _inf2 ^sups =0.74 to 1.0 and S _inf2 ^supf =0.52 to 0.96). Relaxation processes were described as governed by the motion of the sugar relative to the base and in terms of bending of the whole duplex. The possible role played by the special structure of the AATT sequence is discussed. No evident correlation was found between the amplitude motions of the complementary residues. The 5-terminal residues showed large internal motions (S²=0.5), which describe the fraying of the double helix. Global examination of the microdynamical parameters S _inf2 ^supf and S _inf2 ^sups along the nucleotide sequence showed that the adenine residues exhibit more restricted fast internal motions (S _inf2 ^supf =0.88 to 0.96) than the others, whereas the measured relaxation rates of the four nucleosides in solution were mainly of dipolar origin. Moreover, the fit of both R(C_z) and R(HzC_z) experimental relaxation rates using an only global correlation time for all the residues, gave evidence of a supplementary relaxation pathway affecting R(C_x,y) for the purine residues in the (53) G₄A₃ and A₁₀A₉T₈T₇ sequences. This relaxation process was analyzed in terms of exchange stemming from motions of the sugar around the glycosidic bond on the millisecond time scale. It should be pointed out that these residues gave evidence of close contacts with the protein in the complex with the lac operator [Boelens et al. (1987) J. Mol. Biol., 193, 213–216] and that these motions could be implied in the lac-operator-lac-repressor recognition process.     

Erratum: Cloning and sequencing of the phycocyanin gene from Spirulina maxima and its evolutionary analysis

The genes were cloned for the two apoprotein subunits, and ,of phycocyanin from the cyanobacterium Spirulina maxima = Arthrospiramaxima) strain F3. The - and -subunit gene-coding regionscontain 489 bp and 519 bp, respectively. The -subunit gene is upstreamfrom the -subunit gene, with a 111-bp segment separating them.Similarities between the -subunits of S. maxima and nine othercyanobacteria were between 58% and 99%, as were those between the -subunits. The maximum similarity between the - and -subunits from S. maxima was 27%.     

Mycolic acid patterns of some species of Mycobacterium

Representative strains of some species of Mycobacterium were degraded by both acid and alkaline methanolysis. Two-dimensional thin-layer chromatography was used to determine the patterns of mycolic acids and other long-chain components in these methanolysates. Patterns composed of -, methoxy- and ketomycolates were found in Mycobacterium asiaticum, Mycobacterium bovix, Mycobacterium gastri, Mycobacterium gordonae, Mycobacterium kansasii, Mycobacterium marinum and Mycobacterium tuberculosis; a representative of Mycobacterium thermoresistibile also contained lower molecular weight -mycolates in addition to these three acids. In representatives or Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium nonchromogenicum, Mycobacterium novum, Mycobacterium paratuberculosis, Mycobacterium scrofulaceum, Mycobacterium terrae, Mycobacterium xenopi, and Mycobacterium sp. MNC 165 - and ketomycolates were accompanied by -carboxymycolates and 2-eicosanol and homologous alcohols which are derived from wax-ester mycolates. Mycobacterium fortuitum and Mycobacterium giae contained - and epoxymycolates and both serovars of Mycobacterium simiae had a very characteristic pattern of -, - and ketomycolic acids. Comparison with data for other mycobacteria showed the chemotaxonomic significance of these mycolic acid patterns.Abbreviations TLC thin-layer chromatography - TBDMS t-butyldimethylsilyl Supplementary data: Copies of the chromatographic patterns of the mycolic acids from all the strains examined can be provided on request from one of the authors (D.E.M.)     

A method for the investigation of those transformations under which the visual recognition of a given object is invariant

An experiment is described which shows in operation the program set out in Foster (1972a) for the investigation of the invariance transformations of visual recognition. The concern in the present study is with the Lie group of rotations SO(2), and a certain centrally located foveal Landolt ring. By presenting to the visual system this Landolt ring and a rotated image in rapid succession, one attempted to induce a specified rotation-type phi-motion. Two subjects were employed. Both reported the existence of the required type of phi-motion for rotations ₀ of the Landolt ring about the visual axis with -2/72/7. By appealing to the basic Proposition 2 of Foster (1972 a), the conclusion is reached that the visual system appears capable of effecting upon a certain centrally located foveal annulus the local 1-parameter group of rotations about the visual axis ₀, [–2/7,2/7].     

Adsorption equilibrium and dynamics of lactase/CM-Sephadex system

Summary Partitioning behaviour and adsorption isotherms of lactase/CM-Sephadex system at equilibrium were investigated together with the adsorption kinetics in this study. Maximum adsorption was obtained at the pH values between 5.5–6.0. Adsorption isotherm was a close fit to the Langmuir model.Nomenclature a specific mass transfer area - D_m molecular diffusion coefficient (m²/sec) - e₁, e₂ charge of the protein and the gel - k apparent mass transfer coefficient (s^-1) - ka global mass transfer coefficient - f partition coefficient - K_p dissociation constant for adsorbent-adsorbate complex, (mg/mL solvent) - p equilibrium concentration of free enzyme, (mg free enzyme/mL solution) - q equilibrium concentration of adsorbed enzyme, (mg ads./mL gel) - q_m maximum adsorption capacity, (mg ads./ml gel) - Re particle Reynolds number - Sh Sherwood number - V_g/V gel volume (mL)/bulk solvent volume (mL) - Z dimensionless extent of adsorption - K_p/P_o , model parameter - (/) +1 , model parameter - V_g q_m / V P_o , model parameter     

The effect of different growing conditions on water relations parameters of leaf epidermal cells of Tradescantia virginiana L.

Summary Tradescantia virginiana L. plants were cultivated under contrasting conditions of temperature, humidity, light quality and intensity, and nutrient status in order to investigate the effect of growth conditions on the water relations parameters of the leaf epidermal cells. Turgor pressure (P), volumetric elastic modulus (), half-time of water potential equilibration (T _1/2), hydraulic conductivity (L _p ) were measured with the miniaturized pressure probe in single cells of the upper and lower epidermis of leaves. Turgor differed (range: 0.1 bar to 7.2 bar) between treatments with lowest values under warm and humid conditions and additional supply of fertilizer, and highest values under conditions of low air humidity and low nutrient supply. The volumetric elastic modulus changed by 2 orders of magnitude (range: 3.0 bar to 350 bar, 158 cells), but was only affected by the treatments, in as much as it was dependent on turgor. The turgor dependence of , measured on intact leaves of T. virginiana, was similar to that for cells of the isolated (peeled) lower epidermis, where as a function of turgor was linear over the whole range of turgors. This result has implications for the discussion of pressure/volume curves as measured by the pressure bomb where changes in bulk leaf are frequently discussed as adaptations to certain treatments. The measurements of the hydraulic conductivity indicate that this parameter varies between treatments (range of means: 2.4×10^-6 cm s^-1 bar^-1 to 13.4×10^-6 cm s^-1 bar^-1). There was a negative correlation for L _p in cells of intact leaves as a function of turgor which was altered by the growing conditions. However, a correlation with turgor could not be found for cells from isolated epidermis or cells from a uniform population of plants. The large variation in L _p from cell to cell observed in the present and in previous studies was accounted for in a study of 100 cells from a uniform population of plants by the propagation of measurement errors in calculating L _p . The results suggest that in T. virginiana cellular water relations are changed mainly by the turgor dependence of .     

The relation of proton motive force,adenylate energy charge and phosphorylation potential to the specific growth rate and efficiency of energy transduction inBacillus licheniformis under aerobic growth conditions

The magnitude of the proton motive force (p) and its constituents, the electrical () and chemical potential (-ZpH), were established for chemostat cultures of a protease-producing, relaxed (rel ^–) variant and a not protease-producing, stringent (rel ⁺) variant of an industrial strain ofBacillus licheniformis (respectively referred to as the A- and the B-type). For both types, an inverse relation of p with the specific growth rate was found. The calculated intracellular pH (pH_in) was not constant but inversely related to . This change in pH_in might be related to regulatory functions of metabolism but a regulatory role for pH_in itself could not be envisaged. Measurement of the adenylate energy charge (EC) showed a direct relation with for glucose-limited chemostat cultures; in nitrogen-limited chemostat cultures, the EC showed an approximately constant value at low and an increased value at higher . For both limitations, the ATP/ADP ratio was directly related to .The phosphorylation potential (G'p) was invariant with . From the values for G'p and p, a variable H⁺/ATP-stoichiometry was inferred: H⁺/ATP=1.83+0.52µ, so that at a given H⁺/O-ratio of four (4), the apparent P/O-ratio (inferred from regression analysis) showed a decline of 2.16 to 1.87 for =0 to _max (we discuss how more than half of this decline will be independent of any change in internal cell-volume). We propose that the constancy of G'p and the decrease in the efficiency of energy-conservation (P/O-value) with increasing are a way in which the cells try to cope with an apparent less than perfect coordination between anabolism and catabolism to keep up the highest possible with a minimum loss of growth-efficiency. Protease production in nitrogen-limited cultures as compared to glucose-limited cultures, and the difference between the A- and B-type, could not be explained by a different energy-status of the cells.Abbreviations CCCP carbonylcyanide-p-trichloromethoxyphenylhydrazone - DW dry weight of biomass - F Faraday's constant, 96.6 J/(mV × mol) - Fo chemostat outflow-rate (ml/h) - FCCP carbonylcyanide-p-trifluoromethoxyphenylhydrazone - G'p phosphorylation potential, the Gibbs energy change for ATP-synthesis from ADP and P_i - G'⁰p standard Gibbs energy change at specified conditions - H⁺/ATP number of protons translocated through - ATP synthase in synthesis of one ATP - H⁺/O protons translocated during transfer of 2 electrons from substrate to oxygen - specific growth rate (1/h) - _H+ transmembrane electrochemical proton potential, J/mol - M_b molar weight (147.6 g/mol) of bacteria with general cell formula C_6.0H_10.8O_3.0N_1.2 - pH_out,in extracellular, intracellular pH - P_i (intracellular) inorganic phosphate - p proton motive force, mV - pH transmembrane pH-difference - transmembrane electrical potential, mV - P/O number of ADP phosphorylated to ATP upon reduction of one O^2– to H₂O by two electrons transferred through the electron transfer chain - P/O (H⁺/O) × (H⁺/ATP)^–1 - P/O_F, P/O_N P/O with the two electrons donated by resp. (NADH + H⁺) and FADH - q specific rate of consumption or production (mol/g DW × h) - rel ⁺,rel ^– stringent, relaxed genotype - R universal gas constant, 8.36 J/(mol × degree) - T absolute temperature - TPMP⁺ triphenylmethylphosphonium ion - TPP⁺ tetraphenyl phosphonium ion - Y growth yield, g DW/mol - Z conversion constant=61.8 mV for 310 K (37 °C) - ZpH transmembrane proton potential or chemical potential, mV     

Polysaccharide-enriched fraction isolated from Duchesnea chrysantha protects against oxidative damage

Reactive oxygen species (ROS)-related oxidative damages have been implicated in a wide variety of the pathological processes such as atherosclerosis, inflammation and carcinogenesis. A polysaccharide-enriched fraction (PEF) was isolated from Duchesnea chrysantha, a herbaceous plant, and its antioxidant activity was demonstrated using several assay systems in vitro. The PEF effectively inhibited Cu²⁺-stimulated low density lipoprotein oxidation in a concentration-dependent way and retarded the conjugated diene formation with the enhancement of the lag phase during oxidation. An assay for DNA strand breaks showed that PEF strongly protected DNA against damage caused by UV or by OH or O₂ ^– generated in the metal-catalyzed oxidation system. PEF effectively inhibited Nitroblue Tetrazolium reduction mediated by O₂ ^– in a dose-dependent manner. It also competed with 2-deoxy-d-ribose in absorbing OH generated by -irradiation (600 Gy) and thus inhibited the formation malondialdehyde. In conclusion, these evidences indicate that PEF may act as an antioxidant to scavenge O₂ ^–, OH or LO₂ directly. Our findings suggest the possibility that it may play a role as a potential therapeutic antioxidant in treatment of oxidative damage-derived diseases.     

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.     

New expanded bed adsorbents for the recovery of DNA

A 20–40 m pellicular high density (3.7 g cm^–3) expanded bed material has been designed for the capture of DNA and other large macromolecules. Anion exchangers fashioned out of these supports exhibited dramatically enhanced DNA binding capacities over commercial anion exchange adsorbents (6 mg ml^–1, c.f. 50 g ml^–1 at 10% breakthrough), due to a combination of small particle and fuzzy surface architecture created through the coupling of polyethylene imine chains.     

Effects of α-galactosidase digestion on lectin staining in human pancreas

Summary Effects of -galactosidase (from green coffee beans) digestion on lectin staining were examined in formalin-fixed, paraffin-embedded human pancreatic tissues from individuals of blood-group B and AB. Digestion with the enzyme resulted in almost complete loss of Griffonia simplicifolia agglutinin I-B₄(GSAI-B₄) staining in the acinar cells with concomitant appearance of Ulex europaeus agglutinin-I(UEA-I) staining in the corresponding cells. In addition, reactivity with soybean agglutinin(SBA) was also imparted by the enzyme digestion in GSAI-B₄ positive acinar cells. -Galactosidase digestion following -galactosidase digestion neither reduced the reactivity with SBA nor induced the reactivity with Griffonia simplicifolia agglutinin-II(GSA-II) in GSAI-B₄ positive cells, while in UEA-I positive cells, both reduction of SBA reactivity and appearance of GSA-II reactivity occurred after simple -galactosidase digestion as well as sequential digestion with - and -galactosidase. However, when -l-fucosidase digestion procedure was inserted between - and -galactosidase digestion, UEA-I staining imparted by -galactosidase digestion was markedly decreased in intensity and GSA-II reactivity was appeared in GSAI-B₄ positive acinar cells. Furthermore, after sequential digestion with -galactosidase and fucosidase, reactivity with peanut agglutinin(PNA) was revealed in GSAI-B₄ positive acinar cells as well as UEA-I positive cells in secretors. In non-secretors, strong PNA staining was usually observed in the acinar cells throughout the glands without enzyme digestion. These results confirmed that the -galactosidase induced GSA-II reactivity and the fucosidase induced PNA reactivity are due to precursors of different kinds of blood-group determinants and suggest that at least two kinds of B antigen determinants, i.e. Gal(1-3)[Fuc(1-2)]Gal(1-3,4)GlcNac and Gal(1-3)-[Fuc(1-2)]Gal(1-3)GalNAc are produced in GSAI-B₄ positive acinar cells. The synthesis of the latter type of B antigen is assumed to be controlled under the secretory gene in human pancreas.Abbreviation GalNAc N-acetyl-d-galactosamine - Gal d-galactose - GlcNAc N-acetyl-d-glucosamine - Fuc l-fucose - NeuNAc N-acetylneuraminic acid (sialic acid)     

Adherence of a virulent strain of Listeria monocytogenes to the surface of a hepatocarcinoma cell line via lectin-substrate interaction

Listeria monocytogenes was examined for the presence of surface carbohydrates to ascertain whether surface sugars, if present, would interact with eucaryotic surface carbohydrate receptors. We found that a virulent, but not two avirulent strains had a surface -d-galactose residue as determined by agglutination with Griffonia simplicifolia (GS-I) and other lectins. The virulent strain bound to a human hepatocarcinoma cell line (HepG2), which has a well characterized receptor for -d-galactose. This interaction could be blocked by pretreatment of the HepG2 cells with either -d-galactose or neuraminidase, the latter of which will render the galactose receptor functionally inactive. We propose that the attachment of the virulent Listeria to eucaryotic cells occurs as a result of the interaction of the microbial -d-galactose with that of the eucaryotic galactose receptor. This surface carbohydrate may provide an explanation for the mechanism of attachment and penetration of virulent Listeria into host cells during infection. As such, this may allow for amplication of pathogenesis through intracellular multiplication in nonprofessional phagocytes prior to macrophage involvement.Abbreviations ATCC 19113 and ATCC 4428 Listeria monocytogenes, avirulent strains - EDG Listeria monocytogenes, virulent strain - GS-I Griffonia simplicifolia lectin - GepG2 Human, hepatocarcinoma cells - MES buffer 2(N-Morpholino)-ethane sulfonic acid - PBS buffer phosphate buffered saline This work was carried out and submitted in part by JL to the 47th Annual Westinghouse Science Talent Search while a senior at Union High School, Tulsa, OklahomaRecipient of a National Merit Scholarship Award. Presently attending Southwest Missouri State University, Springfield, Missouri     

Effects of competition and N and P supply on carbon isotope discrimination and <Superscript>15</Superscript>N-natural abundance in four grassland species

The effect of interspecific competition and element additions (N and P) on four grassland species (Poa pratensis, Lolium perenne, Festuca valida, Taraxacum officinale) grown under field conditions was studied. Two grasses (L. perenne, F. valida) grown in monoculture (absence of competition) showed lower carbon isotope discrimination (¹³C) and enriched ¹⁵N values. Nitrogen addition (as urea) had inconsistent effects on species ¹³C while caused enrichment of ¹⁵N of P. pratensis and F. valida but strong depletion of ¹⁵N of T. officinale. Phosphorous had no significant effect on ¹³C but depleted ¹⁵N of all species.