Amino acid deletions in loop C of the chlorophyll a-binding protein CP47 alter the chloride requirement and/or prevent the assembly of photosystem II

The chlorophyll a-binding protein CP47 directs excitation energy to the reaction center of photosystem II (PSII) during oxygenic photosynthesis and has additional structural and functional roles associated with the PSII water-oxidizing complex. Oligonucleotide-directed mutagenesis was employed to study loop C of CP47 (approximately Trp-162 to Gly-197) which faces the thylakoid lumen. Five short amino acid deletion strains, (S169–P171), (Y172–G176), (G176–P180), (E184–A188) and (F190–N194), were created that span this domain. The deletion between Gly-176 and Pro-180, located around the middle of loop C, produced an obligate photoheterotroph that could not assemble functional PSII centers. The deletions in mutants (S169–P171) and (Y172–G176) reduced PSII levels to 20% of the control and thus impaired photoautotrophic growth. In contrast, mutants (E184-A188) and (F190–N194) were photoautotrophic even though the number of photosystems was decreased by 50%. All PSII complexes assembled in the deletion strains had an increased susceptibility to photoinactivation and deletion of Glu-184 to Ala-188 prevented photoautotrophic growth under chloride-limiting conditions. Furthermore, the removal of the extrinsic PSII-O, PSII-U and PSII-V proteins from mutants (E184–A188) and (F190–N194) reduced the rates of oxygen evolution and, in the strains lacking either the PSII-O or PSII-V proteins, also increased the photoautotrophic doubling times. These effects were greater in mutant (E184–A188) than in mutant (F190–N194) and the order of importance for the removal of the extrinsic proteins was found to be PSII-V PSII-O > PSII-U.     

Is There a Field-Theoretic Explanation For Precursor Biopolymers?

A Hu-Barkana-Gruzinov cold dark matter scalarfield may enter a weak isospin invariant derivative interactionthat causes the flow of right-handed electrons to align parallelto (). Hence, in the outer regions of galaxies where () islarge, as in galactic halos, the derivative interaction mayinduce a chirality-imbued quantum chemistry. Such a chirality-imbued chemistry would in turn be conducive to the formation ofabundant precursor biopolymers on interstellar dust grains,comets and meteors in galactic halo regions, with subsequentdelivery to planets in the inner galactic regions where and() are concomitantly near zero and left-right symmetricterrestrial quantum chemistry prevails.     

Post-translational modifications of α-tubulin in<Emphasis Type="Italic"> Zea mays</Emphasis> L. are highly tissue specific

To further understand post-translational modifications (PTMs) of plant -tubulin, post-translationally modified -tubulin isoforms from selected tissues of Zea mays L. were examined using two-dimensional electrophoresis and immunoblotting. Except for polyglycylated tubulin, tyrosinated, detyrosinated, acetylated and polyglutamylated -tubulin isoforms were all present in maize tissues. Tyrosinated -tubulin was the predominant variant in all cases, with isoforms 1–4 (5) being the most common components. Leaves exhibited a striking difference in PTM patterns of -tubulin isoforms compared to other tissues examined. In leaves, several major specific isoforms were highly modified by detyrosination, acetylation and polyglutamylation. In pollen and anthers, only the most abundant isoform 3 was acetylated to an appreciable extent, and no acetylated isoform was found in roots. Similarly, in pollen, anthers and roots, only 3 was appreciably polyglutamylated. Additionally, a detyrosinated isoform 6 was present in anthers and in leaves, while the tyrosinated isoform 6 seemed to be pollen specific. These results indicate that certain types of PTM of plant -tubulin preferentially occur in a tissue-specific way.Abbreviations 1-, 2-D one-, two-dimensional - MT microtubule - PTM post-translational modification     

Synthesis of hexaploid (AABBCC) somatic hybrids: a bridging material for transfer of ‘tour’ cytoplasmic male sterility to different Brassica species

Most of the alloplasmic cytoplasmic male sterility (CMS) systems are known to be associated with a number of floral abnormalities that result from nuclear-cytoplasmic incompatibilities. One such system, tour, which is derived from Brassica tournefortii, induces additional floral abnormalities and causes chlorosis in Brassica spp. While the restorer for this CMS has been reported to be present in B. napus, in B. juncea, where the abnormalities are more pronounced, no restorer has yet been identified. Rectification of these floral abnormalities through mitochondrial recombinations and chloroplast replacement might result in the improvement of this CMS system. As organelle recombinations can possibly be achieved only by somatic cell hybridization, fusion experiments were carried out between hygromycin-resistant B. juncea AABB carrying tour cytoplasm and phosphinotricin-resistant, normal B. oleracea CC to generate AABBCC hexaploid somatic hybrids. The presence of selectable marker genes facilitated the selection of hybrids in large numbers. The resulting hybrids showed wide variation in floral morphology and organelle composition. Regenerants with normal, male-sterile flowers having recombinant tour-or oleracea-type mitochondria and oleracea-type chloroplasts were obtained. Hybrids with male-fertile flowers were also obtained that had recombined tour mitochondria. The AABBCC hexaploid hybrids synthesized in the present study were successfully utilized as a bridging material for transferring variability in the organelle genome simultaneously to all the digenomic Brassica species, and all of these hybrids are now being stabilized through repeated backcrosses to the allopolyploid crop brassicas.     

Molecular mapping of a new gene Rrs4 CI 11549 for resistance to barley scald (Rhynchosporium secalis)

Doubled haploid (DH) progeny from a cross between the scald susceptible barley (Hordeum vulgare L.) cultivar Ingrid and the resistant accession CI 11549 (Nigrinudum) was evaluated for resistance in the pathogen Rhynchosporium secalis (Oudem) J.J. Davis. Two linked and incompletely dominant loci confer resistance CI 11549 against isolate 4004. One is an allele at the complex Rrs1 locus on chromosome 3H close to the centromere; the other is located 22 cM distally on the long arm. The latter locus is designated Rrs4. In BC₃-lines into Ingrid from CI 2222 (another Nigrinudum) resistance seems governed by one locus close to the telomeric region of chromosome 7H, probably allelic to Rrs2. In neither case did we find any trace of the recessive gene rh8 reported to be present in Nigrinudum. Various resistance donors of Ethiopian origin designated as Nigrinudum, Jet or Abyssinian were identical to a great extent with respect to markers, but differed in resistance to different isolates of scald or in barley yellow dwarf virus (BYDV) resistance. The implications for their use as differentials in scald tests and screening of germplasm collections are discussed.     

Nuclear Overhauser effect investigation on GM1 ganglioside containingN-glycolyl-neuraminic acid (II3Neu5GcGgOse4Cer)

The conformational properties of the oligosaccharide chain of GM1 ganglioside containingN-glycolyl-neuraminic acid, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer, were studied through NMR nuclear Overhauser effect investigations on the monomeric ganglioside in dimethylsulfoxide, and on mixed micelles of ganglioside and dodecylphosphocholine in water. Several interresidual contacts for the trisaccharide core--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-were found to fix the relative orientitation of the three saccharides, while the glycosidic linkage of the terminal -Gal-was found to be quite mobile as the -Gal-(1-3)--GalNAc-disaccharide exists in different conformations. These results are similar to those found for two GM1 gangliosides containingN-acetyl-neuraminic acid and neuraminic acid [1].Abbreviations Ganglioside nomenclature is in accordance with Svennerholm [23] and the IUPAC-IUB Recommendations [24] GM3(Neu5Ac) II³Neu5AcLacCer, -Neu5Ac-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer - GM3(Neu5Gc) II³Neu5GcLacCer, -Neu5Gc-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu5Ac) II³Neu5AcGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu5Gc) II³Neu5GcGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu) II³NeuGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu-(2-3)]--Glc-(1-1)-Cer - GD1a IV³Neu5AcII³Neu5AcGgOse₄Cer, -Neu5Ac-(2-3)--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GalNAc-GD1a IV⁴GalNAcIV³Neu5AcII³Neu5AcGgOse₄Cer, -GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - Neu neuraminic acid - Neu5Ac N-acetyl-neuraminic acid - Neu5Gc N-glycolyl-neuraminic acid - Cer ceramide     

Ganglioside lactones:1H-NMR determination of the inner ester position of GD1b-ganglioside lactone naturally occurring in human brain or produced by chemical synthesis

The complete definition of the chemical structure of G_D1b-ganglioside (G_D1b) lactone isolated from human brain has been given by means of spectrometric and spectroscopic analyses. G_D1h lactone contains a single ester linkage involving the external sialic acid carboxyl group and the C-9 hydroxyl group of the internal sialic acid unit. A synthetic lactone of G_D1b prepared treating G_D1b with glacial acetic acid characterized in the same way showed an identical chemical structure.Abbreviations: Ganglioside nomenclature is according to Svennerholm [16] and the IUPAC-IUB Recommendations [17] G_M1 G_M1-ganglioside, II³NeuAc-GgOse₄Cer, Gal1-3GalNac1-4[NeuAc2-3]Gal1-4Glc1-1Cer - G_D1b G_D1b-ganglioside, II³(NeuAc)₂GgOse₄Cer, Gal1-3GalNAc1-4[NeuAc2-8NeuAc2-3]Gal1-4Glc1-1Cer - G_D1b lactone G_D1b-L, Gal1-3GalNAc1-4[NeuAc(1-9)2-8NeuAc2-3]Gal1-4Glc1-1Cer - Cer ceramide - FAB-MS fast atom bombardment-mass spectrometry - ¹H-NMR proteon nuclear magnetic resonance - 1D-NMR one dimensional NMR - 2D-COSY two dimensional correlated spectroscopy - DMSO-d₆ deuterated dimethylsulfoxide     

Transforming Growth Factor α (TGFα) Modulates the Effects of Genomic Imprinting and Prolongs Development of Parthenogenetic Mouse Embryos

The effect of transforming growth factor (TGF) on the development of diploid parthenogenetic mouse embryos (CBA × C57BL/6)F₁was studied. The embryos were in vitro treated with the TGF at the morula stage. Upon reaching the blastocyst stage, each embryo was implanted into uterus of a pseudopregnant female. At a dose of 5 ng/ml, the TGF was found to improve development of parthenogenetic embryos before implantation, increase significantly the number of developing blastocysts, and promote embryo implantation into uterus. After treatment with TGF at a dose of 10 ng/ml, 4% of parthenogenetic embryos reached the stage of 30–45 somites and had forelimb and hindlimb buds; the crown rump length of the embryo size from vertex to sacrum was 2.0 to 3.8 mm. A well-developed placenta was observed in 6% of TGF-treated parthenogenetic embryos that reached the somite stages. In the parthenogenetic embryos with the most prominent development (40–45 somites) treated with 10 ng/ml of TGF, the placental diameter was 4.0 to 4.2 mm on day 12 of gestation, which is close to the placental size of the normal (fertilized) 11-day-old mouse embryos. Our results suggest that exogenous TGF can modulate the effects of genomic imprinting significantly improving formation of trophoblast derivatives and promoting longer postimplantation development of parthenogenetic embryos.     

Identification of a glutathione-S-transferase effector domain for inhibition of jun kinase, by molecular dynamics

We have recently found that the glutathione-S-transferase -isozyme (GST-), a cellular detoxification enzyme, potently and selectively inhibits activation of jun protein by its upstream kinase, jun kinase (JNK). This newly identified regulatory activity of GST- is strongly inhibited by a group of agents that inhibit its enzymatic activity. Since loss of enzymatic activity in general does not correlate with loss of regulatory activity, it is likely that inhibitor binding induces changes in the structure of one or more domains of GST that block its interaction with JNK. To identify regions of GST that change conformation on the binding of inhibitors, we have performed molecular dynamics calculations on GST- to compute its average structure in the presence and absence of the inhibitor, glutathione sulfonate. Superposition of the two average structures reveals that several regions change local structure depending upon whether the inhibitor is bound or not bound. Two of these regions, residues 36–50 and 194–201, are highly exposed. We have synthesized peptides corresponding to these two segments and find that the 194–201 sequence strongly inhibits the ability of GST- to block the in vitro phosphorylation of jun by JNK. These results suggest that this region of GST- is critical to its functioning as a newly discovered regulator of signal transduction.     

Purification and immunocytochemical localization of kafirins inSorghum bicolor (L. Moench) endosperm

Summary Kafirins are the storage proteins of sorghum and are found in protein bodies in the seed endosperm. They have been classified as -, -, and -kafirins according to differences in molecular weight, solubility, and structure. The kafirins were purified, amino acid composition was determined, and immunolocalization methods were used to determine the organization of the protein bodies and distribution of kafirins throughout the endosperm. All three groups of kafirins were low in lysine. -Kafirins and -kafirins were relatively high in cysteine, and -kafirins were relatively high in methionine. Transmission electron microscopy showed that protein bodies in the peripheral endosperm were spheroid with concentric rings and few darkly stained inclusions. In contrast, protein bodies of the central endosperm were irregularly shaped with a higher proportion of darkly stained material. The light staining regions of the protein bodies are composed primarily of -kafirins with minor portions of - and -kafirins. The dark staining regions, however, are composed primarily of - and -kafirins. Immunoelectron microscopy showed that protein bodies in the peripheral endosperm contain predominantly a-kafirin with minor amounts of - and -kafirin. Central endosperm protein bodies are also predominantly -kafirin, but have a higher proportion of -kafirin and -kafirin than the peripheral endosperm protein bodies.Abbreviations GAR-HRP Goat anti-rabbit horseradish peroxidase - IgG immunoglobulin G - 2-ME 2-mercaptoethanol - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis - TBS Tris buffer saline - TBS-T Tris buffer saline with Tween - TBS-T-B Tris buffer saline with Tween and bovine serum albumin - TCA trichloroacetic acid - UV ultraviolet     

Cytological characterization,powdery mildew resistance and storage protein composition of tetraploid and hexaploid 1BL/1RS wheat-rye translocation lines

Summary Progenies of a tetraploid 1BL/1RS wheat-rye translocation line, CV 256, selected from the cross Cando x Veery, were analyzed by means of Giemsa C-banding. CV 256 is cytologically stable for the presence of the 1BL/1RS translocation but still segregating for A- and B-genome chromosomes of Cando and Veery. In CV 256, nucleolar activity of the 1RS NOR locus is suppressed, as judged by the absence of a secondary constriction in that rye segment and the capability of organizing nucleoli. PAGE analysis of prolamins confirmed the presence of two 1RS secalins in all single seeds analyzed. SDS-PAGE analysis of reduced glutenins of single seeds indicated that some seeds contained the Cando Glu-B1 locus (subunits 6+8), some contained the Veery Glu-B1 locus (subunits 7+9) while others contained all four subunits, indicating that the material was heterozygous. Pm8 resistance is expressed in the tetraploid 1BL/1RS translocation line based on the reactions of six well-defined powdery mildew isolates. However, Pm8 resistance is not expressed in the hexaploid wheat cultivars Olymp, Heinrich and Florida, which also contain the 1BL/1RS translocation. Obviously, the existence of the 1BL/1RS translocation is not a proof for the expression of the associated genes. PAGE results did not show a clear linkage between powdery mildew resistance and the presence of 1RS secalins.     

The glycolipid specificity ofErythrina cristagalli agglutinin

The interaction of¹²⁵I-labeledErythrina cristagalli agglutinin (ECA) with neutral glycosphingolipids on thin layer chromatograms was examined by the overlay technique followed by radioautography. The lectin bound topara-globoside with a sensitivity about 10 times higher than to lactosylceramide or globoside, in agreement with the specificity of the lectin forN-acetyllactosamine. The lower limit of detection ofpara-globoside was about 0.66 nmol. The specific binding of ECA to this glycolipid was confirmed by a highly sensitive enzyme-linked lectin assay (ELLA), utilizing the horseradish peroxidase-avidin-biotin system for detection of bound lectin. Overlays of neutral glycosphingolipid extracts from human erythrocyte membranes and from human granulocytes with ECA demonstrated that the lectin can be employed for the detection of small amounts ofpara-globoside in biological materials also in the presence of excess globoside. No staining was obtained when thin layer chromatograms of neutral glycosphingolipid extracts from rabbit erythrocyte membranes were overlayed with¹²⁵I-ECA. Afterin situ treatment of the chromatograms with -galactosidase, the lectin bound to several components, one of which had a mobility corresponding to that of the pentahexosylceramide Gal3Gal4GlcNAc3Gal4Glc1Cer, the major neutral glycosphingolipid of rabbit erythrocytes, thus providing further evidence for the specificity of ECA forpara-globoside.Abbreviations GSL glycosphingolipid(s) - CDH lactosylceramide, Gal4Glc1Cer - CTH trihexosylceramide, Gal4Gal4Glc1Cer - GLOB globoside, GalNac3Gal4Gal4Glc1Cer - PG para-globoside, Gal4GlcNAc3Gal4Glc1Cer - AsG_M1 asialo-G_M1, Gal3GalNAc4Gal4Glc1Cer - FORS Forsmann antigen, GalNAc3GalNAc3Gal4Gal4Glc1Cer - CPH pentahexosylceramide, Gal3Gal4GlcNAc3Gal4Glc1Cer - ECA Erythrina cristagalli agglutinin - SBA soybean agglutinin - PBS phosphate-buffered saline - PVP-40 polyvinylpyrrolidone M.W. 40000 - BSA bovine serum albumin - HRP-avidin horseradish peroxidase conjugated to avidin - ELLA enzyme-linked lectin assay - ELISA enzyme-linked immunosorbent assay - PMNL polymorphonuclear leukocytes - HPTLC high performance thin layer chromatography     

High crossability of wild barley (Hordeum spontaneum C. Koch) with bread wheat and the differential elimination of barley chromosomes in the hybrids

Four bread wheat (Triticum aestivum L.) cultivars, Aobakomugi, Chinese Spring, Norin 61 and Shinchunaga, were pollinated with five barley lines/cultivars consisting of three cultivated barley (Hordeum vulgare L.) lines, Betzes, Kinai 5 and OHL089, and two wild barley (Hordeum spontaneum C. Koch) lines, OUH602 and OUH324. Crossability, expressed as the percentage of embryo formation, varied from 0 to 55.4% among the cross combinations. The two wild barley lines generally had a higher crossability than the previously reported best pollinator, Betzes, and some Japanese wheat cultivars were better as the female parent than Chinese Spring. Ninety four hybrid plants were obtained from 250 embryos cultured, and their somatic chromosome numbers ranged from 21 to 36. Eighteen plants were mosaic in chromosome number. Twenty one-chromosome plants appeared most frequently (45.7%) followed by 28-chromosome plants (14.9%). C-banding analysis revealed that elimination of barley chromosomes was mainly responsible for the occurrence of aneuploid plants. In hypoploids derived from Betzes-crosses, chromosome 5 was preferentially eliminated as previously reported, while in hypoploids derived from OUH602-crosses, chromosome 4 was preferentially eliminated. The wild barley line OUH602 may be a useful parent for producing a new wheat-barley addition set because of its high crossability with wheat and a different pattern of chromosome elimination.     

Genetic analysis of brown planthopper resistance in twenty varieties of rice,Oryza saliva L.

Summary The inheritance of resistance to brown planthopper, Nilaparvata lugens (Stol.), of 20 rice cultivars was studied. Single dominant genes that are allelic to Bph 3 condition the resistance in cultivars Ptb 19, Gangala (Acc. 7733), Gangala (Acc. 15207), Horana Mawee, Kuruhondarwala, Mudu Kiriyal and Muthumanikam. Single recessive genes that are allelic to bph 4 govern the resistance in cultivars Gambada Samba, Heenhoranamawee, Hotel Samba, Kahata Samba, Kalukuruwee, Lekam Samba, Senawee, Sulai, Thirissa and Vellai Illankali. The resistance in Ptb 33, Sudu Hondarwala, and Sinna Sivappu is governed by one dominant and one recessive gene which segregate independently of each other. The dominant resistance genes in these cultivars appear allelic to either Bph 1 or Bph 3. Similarly, the recessive genes in these cultivars seem allelic to either bph 2 or bph 4. Further investigations are needed to conclusively determine the allelic relationships of resistance genes in Ptb 33, Sudu Hondarwala and Sinna Sivappu.     

Degradation of 5-pregnene-3β, 20β-diol by a Nocardia sp.

Summary With growing cells of a Nocardia sp., isolated from soil, the degradation of 5-pregnene-3, 20-diol into 3-[5-oxo-7a-methyl-1 (1-hydroxo)-ethyl-3a-perhydroindane-4]-propionic acid was investigated. The results show that iron is essential for production of the perhydroindanpropionic acid, that this production is greatly enhanced by the presence of calcium and that it is maximal in the pH range 7.0–7.5.Abbreviations used in the text PD 5-pregnene-3, 20-diol (pregnendiol) - PDSA 3-[5-oxo-7a-methyl-1(1-hydroxo)-ethyl-3a-perhydroindane-4]-propionic acid (pregnendiol-secoacid) - PSA 3-[5-oxo-7a-methyl-1-acetyl-3a-perhydroindane-4]-propionic acid (progesterone-secoacid) - EDTA Ethylendiamintetracetic acid - DMSO Dimethylsulfoxide     

Pigeon navigation: Site simulation by means of atmospheric odours

Summary 10 experiments were conducted in which a group of experimental pigeons were allowed to smell natural ambient air for a period of 3 h at a site which was 25–55 km away from the loft (false site) and then subsequently released at another site ( true release site ) situated in a roughly diametrical position from home. Controls were directly transported to the true release site, and during the same 3 h period they were allowed to smell natural air there. Except for those 3 h, both controls and experimentals were prevented from smelling atmospheric odours by filtration of the air flowing through the containers in which the birds were held. Air filtration was never interrupted in a third group of birds, which were transported together with the experimentals. All the birds were released under local anaesthesia of their olfactory mucosae. Experiments were performed in pairs: Within each pair of experiments, the site used as false site in the first experiment was the true release site in the second and vice versa.On average, initial bearings of the controls were homeward oriented. Bearings of experimentals, which smelled natural air at the false site, were oriented, with similar accuracy, towards a compass direction pointing from this false site to home, and hence these birds actually flew predominantly away from home (Fig. 4). The third group of pigeons, which never could smell natural air, differed from both of the others in their initial orientation.Faster homing speeds were significantly more frequent in the controls than in the other two treatment types. Experimentals that had smelled falsesite odours were slowest.Thus, pigeons not only can be prevented from orienting their courses homeward by elimination of certain substances from the breathing air, but they also can be systematically misguided by false olfactory information.There was no indication that site-specific stimuli independent of olfaction might additionally be necessary for site localization in pigeons.     

Monocyte-derived dendritic cells that capture dead tumor cells secrete IL-12 and TNF-α through IL-12/TNF-α/NF-κB autocrine loop

This study focused on the question of how monocyte-derived dendritic cells (Mo-DCs) that capture dead tumor cells (Mo-DCs-Tum) secrete interleukin 12 (IL-12) and tumor necrosis factor (TNF-). Mo-DCs-Tum showed higher secretions of IL-12 and TNF- than were shown by Mo-DCs. Enhanced nuclear factor-kappa B (NF-B) activation was also induced in Mo-DCs-Tum within 6 h. The NF-B inhibitor, pyrrolidine dithiocarbamate (PDTC), suppressed both IL-12 and TNF- secretions from Mo-DCs-Tum. Administration of recombinant TNF- or IL-12 enhanced IL-12 or TNF- secretion respectively in Mo-DCs-Tum. Addition of anti-TNF- or anti-IL-12 neutralizing antibody decreased NF-B activation and IL-12 or TNF- secretion in Mo-DCs-Tum. These results suggest that TNF- or IL-12 secretion induces NF-B activation, and it stimulates further TNF- and IL-12 secretions, i.e., an IL-12/TNF-/NF-B autocrine loop, in Mo-DCs-Tum. Thus, Mo-DCs-Tum secrete a large amount of IL-12 and TNF- through accelerated NF-B activation induced by the IL-12/TNF-/NF-B autocrine loop.     

Variability in the 11S globulin fraction of seed storage proteins ofHelianthus (Asteraceae)

The seed storage globulins from sixHelianthus and four hybrids were studied using mono and bidimensional gel SDS electrophoresis (+ 2 mercaptoethanol). The polypeptide composition of each subunit was determined. Different pairs are specifically expressed according to the species studied. Three typical patterns were discriminated. All the studied species exhibit five subunits: two of them are expressed in all the species (₁₁ and ₂₂). The subunit corresponding to the ₁₁ pair is present inH. petiolaris and in the three populations ofH. annuus studied. The _2b2 pair is common toH. annuus andH. argophyllus. H. petiolaris presents two specific _2a2 and ₄₄ pairs andH. annuus a specific ₃₃ pair. InH. argophyllus _{11 33} or ₄₄ are never observed but are replaced by ₁₃ and ₃₁ pairs. Some globulins, poorly represented, are of forms but present chains of higher molecular weights (in the range 54–56 kDa). Expressing variations in the banding patterns between these species by the use of a similarity index reveals complete identity between the three populations ofH. annuus. Identity between the twoH. petiolaris studied is also observed.H. annuus andH. argophyllus appear to be closer to each other thanH. petiolaris concerning the seed storage globulins.     

Stereospecificity and electrogenicity of amino acid transport in Riccia fluitans

In the aquatic liverwort Riccia fluitans, membrane depolarization (_m), change in membrane conductance (g_m), and current-voltage (I-V) characteristics in the presence of different amino acids as well as the uptake of ¹⁴C-labeled amino acids were measured. L-isomers of the tested amino acids generate larger electrical effects (_m, g_m) than D-isomers, and the I-V characteristics show that the positive electrical inward-current of 20 mA m^-2 generated by 0.5 mM D-serine is only about 50% of the current generated by adding 0.5 mM L-serine. Whereas - and -amino acids rapidly depolarize the membrane to the same extend, with -aminobutyric acid (-AB) and dipeptides no significant electrical effects have been measured. The uptake kinetics of ¹⁴C-labeled amino acids display three components: (I) A saturable high-affinity component with K_s-values of 48 M D-alanine, 12 M -aminoisobutyric acid (AIB), 9 M L-alanine, 8 M L-proline, and 6 M L-serine, respectively; (2) an apparently linear low-affinity component, and (3) an also linear but unspecific component at concentrations >20 times the given K_s-value. Uptake of ¹⁴C-labeled AIB can be inhibited competitively by all tested neutral amino acids, the L-isomers being more effective than the D-isomers, as well as by ammonium or methylamine. Vice versa, AIB competitively inhibits uptake of L-serine and L-alanine. It is concluded that an uncharged stereospecific carrier for the investigated amino acids exists in the plasmalemma of Riccia fluitans. Accumulation ratios of about 50 suggest secondary active transport driven by a transmembrane electro-chemical gradient (mainly _m) which is generated by the electrogenic proton pump. It is suggested that this carrier binds to the amino group forming either a charged binary complex with positively charged amines (Felle 1980), or an uncharged complex with -AB or dipeptides, whereas electrogenic transport of - and -amino acids is mediated by a ternary carrier complex, probably charged by a proton.Symbols and Abbreviations _m membrane potential (mV) - E_co equilibrium potential (mV) of the transport system - g_m membrane (slope) conductance (Sm^-2) - g_m change in g_m - I-V curve current-voltage curve - AIB -aminoisobutytric acid - -AB -aminobutyric acid     

A new enzymatic route to the synthesis of 12-ketoursodeoxycholic acid

Summary Cholic acid (3,7,12-trihydroxy-5-cholanoic acid) was completely and selectively transformed into 12-ketoursodeoxycholic acid (3,7-dihydroxy-12-oxo-5-cholanoic acid) by means of two consecutive enzymatic steps catalyzed, the first, by 7- and 12-hydroxysteroid dehydrogenase and, the second, by 7-hydroxysteroid dehydrogenase. Coenzyme regeneration was carried out with -ketoglutarate-glutamate dehydrogenase and glucose-glucose dehydrogenase, respectively.