Phenolic Compound Utilization by the Soft Rot Fungus Lecythophora hoffmannii

Nine phenolic compounds were metabolized by the soft rot fungus Lecythophora hoffmannii via protocatechuic acid and subsequently cleaved by protocatechuate 3,4-dioxygenase as determined by oxygen uptake, substrate depletion, and ring cleavage analysis. Catechol was metabolized by catechol 1,2-dioxygenase. Fungal utilization of these aromatic compounds may be important in the metabolism of wood decay products.     

Evidence for a 13,14-Cis Cycle in Bacteriorhodopsin

We discuss to what extent the vibrational spectra of bacteriorhodopsin that have been observed and assigned by Smith et al. (1, 2) by means of resonance Raman and by Gerwert and Siebert (EMBO (Eur. Mol. Biol. Organ.) J. In press) by means of infrared absorption experiments are in agreement with a photo-cycle of bacteriorhodopsin that involves the sequence BR, IO(all-trans) → K(13,14-cis) → L(13,14-cis) → M(13-cis) → N(13-cis) → O(all-trans). Our discussion is based on a quantumchemical modified neglect of diatomic overlap [MNDO] calculation of the vibrational spectra of the relevant isomers of the protonated retinal Schiff base. In particular, we investigated in these calculations the effects of different charge environments on the frequencies of the relevant C-C single bond stretching vibrations of these isomers.     

Cell specific loss of polarity-inducing ability by later stage mouse preimplantation embryos

The individual blastomeres of the preimplantation mouse embryo become polarized during the 8-cell stage. Microvilli become restricted to the free surface of the embryo and this region of the membrane shows increased labeling with FITC-Con A and trinitrobenzenesulfonate (TNBS). Previous studies have shown that this polarity develops in response to asymmetric cell-cell contact with stage specific induction competent blastomeres. In the present study, the ability of later stage embryos to induce 8-cell polarization has been investigated. Newly-formed, nonpolar 8-cell stage blastomeres (1/8 cells) were isolated, then aggregated with morulae, inner cell clusters (from morulae), blastocysts, or inner cell masses (ICM) and cultured for 8 hr. Aggregates were then assayed for polarity. The results show a hierarchy of inducing ability, with the ICM and IC cluster possessing greater activity than the morula and polar trophectoderm of the early blastocyst, while the mural trophectoderm shows very little inducing activity. Furthermore, the inducing ability of the polar trophectoderm decreases with complete expansion and hatching of the blastocyst. These results indicate that the ability to induce 8-cell blastomere polarization is retained by the embryo beyond the 8-cell stage and that this ability is lost with further differentiation.     

Double immunocytochemical staining for the in situ study of allotype distribution during an anti-trinitrophenyl immune response in chimeric rabbits

After incubation of tissue sections with anti-allotype-enzyme conjugates, the localization of immunoglobulin-allotype-bearing cells in the lymphoid tissues of conventional and chimeric rabbits could be established. The use of anti-allotype sera bearing distinct enzyme labels allowed simultaneous recognition of B cells producing immunoglobulin of one or the other parental types in heterozygous rabbits, or of B cells from the donor and recipient in chimeras. After immunization of chimeric rabbits with trinitrophenyl-keyhole limpet hemocyanin, anti-trinitrophenyl antibody-forming cells could be demonstrated through the use of a trinitrophenyl-alkaline phosphatase conjugate. Simultaneous incubation of sections with this reagent and with horseradish peroxidase coupled to (donor or recipient) anti-allotype sera made possible the determination of the origin (donor or recipient) of the antibody-forming cells. In agreement with the results of plaque assays and analyses of serum antibodies, all the anti-TNP producing cells were of donor origin when the chimeras had been created through injection of spleen or lymph node cells from trinitrophenyl primed donors. With this study we introduce a simple, direct method for the simultaneous identification of cells that produce antibody of a given allotype and a given specificity, applicable to appropriate studies in heterozygous or chimeric rabbits. The procedure has various advantages over previously reported methods.     

A new method for the reconstitution of the anion transport system of the human erythrocyte membrane

Summary The anion transport protein of the human erythrocyte membrane, band 3, was solubilized and purified in solutions of the non-ionic detergent Triton X-100. It was incorporated into spherical lipid bilayers by the following procedure: (1) Dry phosphatidylcholine was suspended in the protein solution. Octylglucopyranoside was added until the milky suspension became clear. (2) The sample was dialyzed overnight against detergentfree buffer. (3) Residual Triton X-100 was removed from the opalescent vesicle suspension by sucrose density gradient centrifugation and subsequent dialysis. Sulfate efflux from the vesicles was studied, under exchange conditions, using a filtration method. Three vesicle subpopulations could be distinguished by analyzing the time course of the efflux. One was nearly impermeable to sulfate, and efflux from another was due to leaks. The largest subpopulation, however, showed transport characteristics very similar to those of the anion transport system of the intact erythrocyte membrane: transport numbers (at 30°C) close to 20 sulfate molecules per band 3 and min, an activation energy of approx. 140 kJ/mol, a pH maximum at pH 6.2, saturation of the sulfate flux at sulfate concentrations around 100mm, inhibition of the flux by H₂DIDS and flufenamate (approx.K _l-values at 30°C: 0.1 and 0.7 m, respectively), and right-side-out orientation of the transport protein (as judged from the inhibition of sulfate efflux by up to 98% by externally added H₂DIDS). Thus, the system represents, for the first time, a reconstitution of all the major properties of the sulfate transport across the erythrocyte membrane.     

Fusion of bacterial spheroplasts by electric fields

Spheroplasts of Escherichia coli or Salmonella typhimurium were found to fuse in an electric field. We employed the fusion method developed by Zimmermann and Scheurich (1981): Close membrane contact between cells is established by dielectrophoresis (formation of chains of cells by an a.c. field), then membrane fusion is induced by the application of short pulses of direct current. Under optimum conditions the fusion yield was routinely 90%. Fusable spheroplasts were obtained by first growing filamentous bacteria in the presence of cephalexin, then converting these to spheroplasts by the use of lysozyme. The fusion products were viable and regenerated to the regular bacterial form. Fusion of genetically different spheroplasts resulted in strains of bacteria possessing a combination of genetic markers. Fusion could not be achieved with spheroplasts obtained by growing the cells in the presence of penicillin or by using lysozyme on bacteria of usual size.     

A plasmodial alpha-tubulin cDNA from Physarum polycephalum. Nucleotide sequence and comparative analysis

As the first step towards correlating structure and function of tubulin in the slime mold Physarum polycephalum we have elucidated the nucleotide sequence of a cDNA that appears to code for all but the last 25 to 30 C-terminal amino acids of a plasmodial alpha-tubulin. Differences in amino acid sequence from those of other alpha-tubulins are distributed fairly evenly throughout the sequence, although a relatively extensive conserved region is found in position 396 to 426 near the C terminus. A small region in position 298 to 307 contains a cluster of amino acid residues unique to Physarum alpha-tubulin. The sequence is 70% homologous to two yeast alpha-tubulins and about 83% homologous to five animal alpha-tubulins. A comparison of the homologies of all the known alpha-tubulins indicates that a large decrease in the accepted point mutation rate has occurred during the evolution of the metazoa, suggesting a major functional specialization of microtubules.     

Is the initiation of macronuclear DNA synthesis in Euplotes dependent on micronuclear functions?

To determine whether the micronucleus makes essential contributions during asexual reproduction, observations were made on cells of Euplotes octocarinatus from which the micronucleus had been removed with a micropipette. Most cells underwent one postenucleation division, then became arrested in macronuclear G1, slowed down in food uptake, developed macronuclear deformations, and finally died. Such cells could be rescued if a micronucleus was reimplanted before macronuclear deformations had developed. When provided with a new micronucleus, cells initiated macronuclear DNA synthesis about 12-16 h later. The data suggest that the micronucleus is involved in the control of the cell's transition from macronuclear G1 to S, and a model is proposed which postulates that in Euplotes macronuclear DNA synthesis is initiated when a micronucleus-encoded "initiator protein" has accumulated to a critical amount.     

Simultaneous and independent effects of abscisic acid on stomata and the photosynthetic apparatus in whole leaves

(±)-Abscisic acid (ABA) at 10^-5 M was added to the transpiration stream of leaves of 16 species (C₃ and C₄, monocotyledons and dicotyledons). Stomatal responses followed one of three patterns: i) stomata that were wide and insensitive to CO₂ initially, closed partially and became sensitive to CO₂; ii) for stomata that were sensitive to CO₂ before the application of ABA, the range of highest sensitivity to CO₂ shifted from high to low intercellular partial pressures of CO₂, for instance in leaves of Zea mays from 170–350 to 70–140 bar; iii) when stomata responded strongly to ABA, their conductance was reduced to a small fraction of the initial conductance, and sensitivity to CO₂ was lost. The photosynthetic apparatus was affected by applications of ABA to various degrees, from no response at all (in agreement with several previous reports on the absence of effects of ABA on photosynthesis) through a temporary decrease of its activity to a lasting reduction. Saturation curves of photosynthesis with respect to the partial pressure of CO₂ in the intercellular spaces indicated that application of ABA could produce three phenomena: i) a reduction of the initial slope of the saturation curve (which indicates a diminished carboxylation efficiency); ii) a reduction of the level of the CO₂-saturated rate of assimilation (which indicates a reduction of the ribulose-1,5-bisphosphate regeneration capacity); and iii) an increase of the CO₂ compensation point. Photosynthesis of isolated mesophyll cells was not affected by ABA treatments. Responses of the stomatal and photosynthetic apparatus were usually synchronous and often proportional to each other, with the result that the partial pressure of CO₂ in the intercellular spaces frequently remained constant in spite of large changes in conductance and assimilation rate. Guard cells and the photosynthetic apparatus were able to recover from effects of ABA applications while the ABA supply continued. Recovery was usually partial, in the case of the photosynthetic apparatus occasionally complete. Abscisic acid did not cause stomatal closure or decreases in the rate of photosynthesis when it was applied during a phase of stomatal opening and induction of photosynthesis that followed a transition from darkness to light.Abbreviations and symbols A rate of CO₂ assimilation - ABA (±)-abscisic acid - c _a partial pressure of CO₂ in the ambient air or in the gas supplied to the leaf chambers - c _i partial pressure of CO₂ in the intercellular spaces of a leaf - e _a partial pressure of H₂O in the air - g conductance for water vapor - J quantum flux - T ₁ leaf temperature     

Chemotherapy and trace element levels in blood and tissue of rats implanted with prostate tumor cells

Male Copenhagen rats with transplanted prostatic adeno-carcinoma were treated with different polyamine synthesis inhibitors, such as methylglyoxal-bis-guanylhydrazone (MGBG), erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) combined with 9-β-d-arabin-ofuranosyl-adenine (ARA-A), α-difluoromethyl-ornithine (DFMO), and some of their combinations. Levels of the essential trace elements—copper, zinc, magnesium, iron, selenium, and manganese —have been determined in blood, tumor, kidney, and liver of these animals and are discussed in terms of efficiency of the treatment. MGBG had the strongest effect on trace element levels in tissues of treated animals. MGBG combined with DFMO exhibited the highest antitumor activity of all treatment protocols. Selenium given as selenite with drinking water was used as an adjuvant with the most toxic combination, (ARA-A/EHNA, MGBG). Selenite reduced the toxicity of these therapeutic agents.