Differential rates of inhibition of N2 fixation by sustained low concentrations of NH4+ and NO3- in northern ecotypes of white clover (Trifolium repens L.)

An experimental study in flowing solution culture compared threeNorwegian ecotypes (from Saerheim, Pasvik and Bod) and a commercialcultivar (Ac51) of white clover (Trifolium repens L.) and demonstrateddifferences with respect to the rate and intensity with whichN₂ fixation was affected when or were supplied at 20 mmol m^–3 over 14 d. Plants were nodulated and N₂ fixation wasestablished over 17 d prior to supplying mineral N, with shoottemperature 25/15 C day/night and root temperature adjustedprogressively to 12C. Control plants received no mineral Nthroughout, and did not grow as rapidly as those supplied with or . Mineral N generally depressed the total N₂ fixation per plantrelative to control plants, with two exceptions. The effectof on N₂ fixation was moresevere than that of and, over the 14 d, -fed plants fixed more N₂ than the comparable -fed plants. Interpolated daily rates of N₂ fixation per plant andnodule dry wts were used to calculate specific rates of N₂ fixation.These showed that (1) addition of either or initially stimulated fixation relative to control plants and to mineral N uptake;(2) this stimulation was greatest and was delayed by 1-2 d in-fed plants; and (3) nutrition sustained higher residualrates of N₂ fixation after 8 d compared with nutrition, under which fixation all but ceased after10 d in three of the genotypes. Ecotype Bode showed by far themost severe induced depression of N₂ fixation. Key words: N₂ fixation, nitrate, ammonium, white clover, northern ecotypes     

Lipochemistry of the progamic stage of a self-incompatible species: Neutral lipids and fatty acids of the secretory stigma during its glandular activity,and of the solid style,the ovary and the anther in Forsythia intermedia Zab. (Heterostylic species)

Chromatographic (thin-layer, gas column, column chromatography) analyses of neutral lipids and fatty acids of reproductive tissues of Forsythia intermedia Zab., a self-incompatible species, were performed with two objectives in mind: 1. To determine whether there is a qualitative evolution of the different classes of lipids and fatty acids that could be correlated with the three functional stages observed during previous histochemical and ultrastructural studies. The stigmatic exudate and intracellular accumulations consist mainly of neutral lipids. 2. To compare the lipid composition of the stigma (both thrum and pin forms) with that of the style, the ovary, and the anther, and to investigate the possible existence of a stigma-specific lipid compound. Stigmatic neutral lipids are found mostly in a glyceridic mixture probably containing hydrocarbons and terpenes. The fatty acids identified are between C:7 and C: 12, with the maximum unsaturated form being a C: 18. During the secretory process there is no great qualitative diference between the neutral lipids and fatty acids found in the stigmas of thrum and pin forms. Sterols are present in styles, ovaries, and anthers, but not in stigmas. They represent the only difference in the lipid composition of these various floral structures.     

Herpes Simplex Virus Type 2 ICP47 Inhibits Human TAP but Not Mouse TAP

Herpes simplex virus serotype 1 (HSV-1) expresses an immediate-early protein, ICP47, that effectively blocks the major histocompatibility complex class I antigen presentation pathway. HSV-1 ICP47 (ICP47-1) binds with high affinity to the human transporter associated with antigen presentation (TAP) and blocks the binding of antigenic peptides. HSV type 2 (HSV-2) ICP47 (ICP47-2) has only 42% amino acid sequence identity with ICP47-1. Here, we compared the levels of inhibition of human and murine TAP, expressed in insect cell microsomes, by ICP47-1 and ICP47-2. Both proteins inhibited human TAP at similar concentrations, and the K_D for ICP47-2 binding to human TAP was 4.8 × 10⁻⁸ M, virtually identical to that measured for ICP47-1 (5.2 × 10⁻⁸ M). There was some inhibition of murine TAP by both ICP47-2 and ICP47-1, but this inhibition was incomplete and only at ICP47 concentrations 50 to 100 times that required to inhibit human TAP. Lack of inhibition of murine TAP by ICP47-1 and ICP47-2 could be explained by an inability of both proteins to bind to murine TAP.Previously, we showed that herpes simplex virus serotype 1 (HSV-1) ICP47 (ICP47-1) caused major histocompatibility complex (MHC) class I proteins to be retained in the endoplasmic reticulum (ER) of cells and that antigen presentation to CD8⁺ T cells was inhibited after ICP47-1 was expressed in human fibroblasts (9). ICP47-1 blocked peptide transport across the ER membrane by TAP (2, 6), so that, without peptides, class I proteins were retained in the ER. By contrast, ICP47 did not detectably inhibit MHC class I antigen presentation in mouse cells (9) and inhibited murine TAP poorly (2, 6). ICP47-1 inhibited peptide binding to TAP without affecting the binding of ATP (1, 7) and bound with high affinity, and in a stable fashion, to human TAP (7). Peptides could competitively inhibit ICP47 binding to TAP, consistent with the hypothesis that ICP47-1 binds to a site which includes the peptide binding domain of TAP (7). Others have suggested that the present data do not exclude a distortion in TAP caused by the binding of ICP47 at a site distant from the peptide binding site (3). This seems improbable given our observations that ICP47 inhibits peptide binding and that peptides competitively inhibit ICP47 binding. In order for peptides to inhibit ICP47 binding and vice versa, one would have to invoke allosteric inhibition by both ICP47 and peptides, a highly unlikely prospect.The predicted amino acid sequence of HSV type 2 ICP47 (ICP47-2) was recently described (3), and it was of some interest that ICP47-1 and ICP47-2 share only 42% amino acid identity (see Fig. ​Fig.1A).1A). Most of the homology is near the N termini and in the central regions of the molecules. A peptide including residues 2 to 35 of ICP47-1 blocked human TAP in permeabilized cells (3). This observation was somewhat surprising given that this peptide did not include residues 33 to 51, a sequence that is most homologous between ICP47-1 and ICP47-2. Presumably, this conserved domain, and even the C-terminal third of the protein, is important in virus-infected cells for stability or for functions that are not apparent in this in vitro assay involving detergent-permeabilized cells.Open in a separate windowFIG. 1Comparison of ICP47-1 and ICP47-2 protein sequences and preparation of purified proteins. (A) The predicted amino acid sequences of ICP47-1 derived from HSV-1 strain 17 (6a) and of ICP47-2 derived from HSV-2 strain HG52 (3) are shown. The boldface, underlined letters denote identical amino acids, and the italicized letters denote conserved residues. (B) ICP47-1 and ICP47-2 were produced in Escherichia coli by expressing the proteins as GST fusion proteins by fusing the ICP47 coding sequences to GST sequences in plasmid pGEX-2T as described previously (7). Lysates from bacteria were incubated with glutathione-Sepharose and washed several times, and then ICP47-1 or ICP47-2 was eluted by incubation with thrombin, which cleaves between the GST and ICP47 sequences (7). The thrombin was inactivated with phenylmethylsulfonyl fluoride, and the ICP47 preparations were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by Bradford protein analysis. The positions of GST-ICP47, GST, and ICP47 protein, as well as those of molecular weight markers 104, 80, 48, 34, 24, and 18 KDa in size, are indicated.Given the differences between the primary structures of ICP47-1 and ICP47-2, we were interested in whether ICP47-2 might inhibit the murine TAP. If this were the case, it would make possible animal studies of the effects of ICP47. Here, we have produced a recombinant form of ICP47-2 and compared the effects of ICP47-2 and ICP47-1 on human and murine TAP proteins expressed in insect cell microsomes. Like ICP47-1, ICP47-2 efficiently blocked human TAP but even at high concentrations did not effectively block murine TAP. Moreover, there was little or no significant binding of either protein to insect microsomes containing mouse TAP.The HSV-2 ICP47 gene was subcloned from plasmid pBB17, which contains a KpnI-HindIII 8,477-bp fragment derived from the genome of HSV-2 strain HG52 inserted into pUC19, by using PCR to amplify ICP47-2 coding sequences. One PCR primer hybridized with the 5′ end of the ICP47-2 coding sequences and extended 5′ to generate a new BglII site just upstream of the initiation codon. The second PCR primer hybridized with 3′ sequences of the ICP47-2 gene, then diverged to produce an EcoRI site just downstream of the translation termination codon. After PCR, the DNA fragment was digested with EcoRI and inserted into the HincII (blunt) and EcoRI sites of pUC19, producing plasmid pUC47-2, which was subjected to DNA sequencing. The ICP47-2 coding sequences were excised from pUC47-2 with BglII and EcoRI and inserted into the BamHI and EcoRI sites of pGEX-2T to generate a fusion protein with glutathione S-transferase (GST). The ICP47-GST fusion protein was expressed in bacteria and purified by using glutathione-Sepharose, and then the GST sequences were removed with thrombin as described previously for ICP47-1 (7). A comparison between the predicted amino acid sequences of ICP47-2 and ICP47-1 is shown in Fig. ​Fig.1,1, with a comparative gel (Fig. ​(Fig.1B)1B) showing the purified preparations of ICP47-1 and ICP47-2 from bacteria. Microsomes purified from Sf9 insect cells infected with baculoviruses expressing human TAP1 and TAP2 have been described previously (7, 8), as were microsomes from Drosophila cells expressing murine TAP1 and TAP2 (1). We previously estimated that approximately 2% of the protein associated with the insect microsomes was human TAP (7), and the microsomes containing mouse TAP possessed similar TAP activity (see below). Peptide translocation by these microsomes was measured by using a library of ¹²⁵I-labelled peptides (5) that are glycosylated after transport into the ER. Radioactive peptides able to bind to concanavalin A were quantified as an indirect measure of peptide transport (6). Over a range of membranes from 2.5 to 20 μl, with protein concentrations of 10 to 12 mg/ml for human TAP microsomes and 5.0 to 7.0 mg/ml for mouse TAP microsomes, there was a linear increase in peptide transport (Fig. ​(Fig.2).2). Thus, peptides and ATP were not limiting. Peptide transport was specific because the transport observed with control membranes not containing TAP amounted to less than 1% of that observed when microsomes contained TAP. The levels of peptide transport associated with microsomes containing human or mouse TAP were also compared and standardized. Thus, in subsequent assays, 7.5 to 10 μl of microsomes exhibiting similar amounts of TAP activity were used. Open in a separate windowFIG. 2Peptide transport by insect microsomes containing human or murine TAP. Microsomes were derived from insect Sf9 cells coinfected with BacTAP1 and BacTAP2 (Human TAP) (7) or from Sf9 cells infected with a control baculovirus, BacgH (Human control). Alternatively, microsomes were derived from Drosophila cells induced to express mouse TAP (Murine TAP) (1) or from Drosophila cells which were not induced to express mouse TAP (Murine control). Various concentrations of each microsome preparation were incubated with ¹²⁵I-labelled peptides and 5 mM ATP in a volume of 150 μl for 10 min at 23°C. The microsomes were washed, pelleted, and disrupted in detergent as described previously (7). Peptides able to bind to concanavalin A-Sepharose were eluted with alpha-methylmannoside and quantified (7).ICP47-2 inhibited peptide transport by human TAP, and the inhibition was similar to that of ICP47-1; the 50% inhibitory concentration (IC₅₀) for ICP47-2 was 0.24 μM and for ICP47-1 was 0.27 μM (Fig. ​(Fig.3A).3A). In other experiments the IC₅₀ values for ICP47-1 and ICP47-2 varied from 0.15 to 0.35 μM, and there were no experiments in which there was a significant difference in the abilities of the two proteins to inhibit human TAP. Moreover, the binding properties of ICP47-2 to human TAP were similar to those of ICP47-1. Binding experiments were performed as described previously for ICP47-1 (7) by using membranes containing human TAP and ¹²⁵I-labelled ICP47-2. Specific binding of ICP47-2 was calculated by subtracting the binding to control microsomes derived from insect cells infected with a baculovirus expressing HSV gH (7). The binding of ICP47-2 was saturable, so that at a protein concentration of 1 μM approximately 16 ng of protein bound to human TAP (Fig. ​(Fig.4A).4A). In previous experiments with a similar preparation of insect microsomes containing human TAP, the binding of ICP47-1 also saturated at 15 to 16 ng (7). The ICP47-2 binding data were analyzed in a standard Scatchard plot, and the K_D was calculated to be 4.8 × 10⁻⁸ M (Fig. ​(Fig.4B),4B), compared with 5.2 × 10⁻⁸ M for ICP47-1 (7). These values are greater than those of high-affinity peptides that bind to human TAP with affinities reaching 4 × 10⁻⁷ M, though the vast majority of peptides bind to TAP with much lower affinities (8). Open in a separate windowFIG. 3Inhibition of human and murine TAP-mediated peptide transport by ICP47-1 and ICP47-2. TAP assays were performed as described in the legend for Fig. ​Fig.22 by using insect microsomes containing human TAP (10 μl of membranes containing 12 mg of membrane protein per ml) (A) or murine TAP (7.5 μl of membranes containing 4.8 mg of membrane protein per ml but with equivalent levels of TAP activity compared with microsomes containing human TAP) (B) and various concentrations of ICP47-1 and ICP47-2. The results shown are combined from two separate experiments, each involving human and murine TAP.Open in a separate windowFIG. 4Binding of ICP47-2 to human TAP. (A) Microsomes (15 μl of membranes with a 7.5-mg/ml concentration of membrane protein) derived from Sf9 cells expressing TAP1 and TAP2 or expressing HSV-1 gH (control membranes not containing TAP) were incubated with various amounts of ¹²⁵I-labelled ICP47-2 for 60 min at 4°C as described previously (7). Binding to control membranes was subtracted from binding to microsomes containing TAP at each point. (B) Scatchard analysis of the data in panel A. The K_D for ICP47-2 binding to TAP was calculated to be 4.8 × 10⁻⁸ M.To determine whether ICP47-2 could inhibit the murine TAP, microsomes from insect cells expressing mouse TAP were incubated with various concentrations of ICP47-1 and ICP47-2 and TAP assays were performed. Inhibition of the mouse TAP was observed with both ICP47-1 and ICP47-2, but relatively high concentrations of both proteins were required (Fig. ​(Fig.3B).3B). The IC₅₀ values for ICP47-1 and ICP47-2 in this experiment were 10.8 and 16.2 μM, respectively. However, we were unable to reduce TAP activity beyond approximately 40% with ICP47-1 or ICP47-2 concentrations reaching 30 μM. This was 100 times the concentration required to inhibit human TAP by 50%. We attempted to measure the specific binding of radiolabelled ICP47-1 and ICP47-2 to microsomes containing mouse TAP in experiments similar to those shown in Fig. ​Fig.4.4. However, there was little specific binding of ICP47-1 and ICP47-2, and it was difficult to measure binding at lower protein concentrations. We therefore measured binding at a single, higher protein concentration (2.75 μM), one sufficient to inhibit 10 to 20% of the mouse TAP activity and all of the human TAP activity. In this experiment, specific binding to microsomes containing murine TAP was determined by subtracting the binding to microsomes from insect cells that were not induced to express murine TAP (1). The binding of ICP47-1 and ICP47-2 to human TAP was easily measured (Fig. ​(Fig.5),5), although under these conditions it is important to note that ICP47-1 and ICP47-2 were present at concentrations beyond those required to saturate the TAP (Fig. ​(Fig.4A).4A). By contrast, it was found that there was little or no significant binding of ICP47-1 or ICP47-2 to microsomes containing murine TAP when background binding to control membranes was subtracted. In the experiment shown, specific ICP47-2 binding was greater than zero, but in other experiments this binding was less than zero, and thus we concluded that there was no detectable binding overall. In every experiment, it was clear that the level of binding of ICP47-1 and ICP47-2 to murine TAP was at least 25-fold lower than to human TAP. However, the human TAP present in these microsomes was limiting in these experiments, and thus it is very likely that the 25-fold difference between the levels of binding to human and mouse TAP is an underestimate. More likely this difference is 50- to 100-fold. On the basis of the inhibitory concentrations required to block murine TAP and the binding studies described above, estimates of the binding affinities of ICP47-1 and ICP47-2 for murine TAP may fall in the range of 5 × 10⁻⁶ M. Therefore, ICP47-1 and ICP47-2 bind poorly to the murine TAP, and this largely accounts for their inability to block mouse TAP peptide transport. Open in a separate windowFIG. 5Binding of ICP47-1 and ICP47-2 to microsomes containing murine TAP. Microsomes containing human TAP or control membranes without human TAP (100 μg of membrane protein per 150-μl assay) or microsomes containing mouse TAP or control membranes without mouse TAP (50 μg of membrane protein with the same TAP activity as with the human microsomes) were incubated with ¹²⁵I-labelled ICP47-1 or ICP47-2 at 2.75 μM for 60 min at 4°C. The microsomes were washed twice, pelleted, and disrupted with detergents as described previously (7). Radioactivity associated with the microsomes was quantified by gamma counting. “ICP47 bound” refers to specific binding, calculated by subtracting the binding to control membranes (without TAP) from that observed with microsomes containing human or murine TAP.In summary, ICP47-2 and ICP47-1 could block human TAP and bound to TAP with similar high affinities. It was interesting that these two proteins, whose primary structures are only about 40% identical, inhibit human TAP with indistinguishable profiles and bind to human TAP with virtually identical affinities. Moreover, both proteins blocked murine TAP poorly and only at high protein concentrations and could not bind to murine TAP. These results, at face value, would suggest that mice will not be an appropriate model in which to test the effects of ICP47 on HSV replication or as a selective inhibitor of CD8⁺ T-cell responses in other systems. However, we recently found that an HSV-1 ICP47 mutant showed dramatically reduced neurovirulence in mice, without altering the course of disease in the cornea (4). Therefore, ICP47 may attain sufficient concentrations in certain cells in the nervous systems of mice to inhibit TAP. This may be related to the fact that TAP and class I proteins are expressed at low levels in the nervous system. Alternatively, ICP47 may have other functions in the nervous system.     

Synthesis of Gal-β-(1→4)-GlcNAc-β-(1→6)-[Gal-β- (1→3)]-GalNAc-α-OBn oligosaccharides bearing O-methyl or O-sulfo groups at C-3 of the Gal residue: specific acceptors for Gal: 3-O-sulfotransferases

Our recent studies have revealed the existence of two distinct Gal: 3-O-sulfotransferases capable of acting on the C-3 position of galactose in a Core 2 branched structure, e.g., Gal14GlcNAc16(Gal13)GalNac1OBenzyl as acceptor to give 3-O-sulfoGal14GlcNAc13(Gal13)GalNAc1OB 20 and Gal14GlcNAc16(3-O-sulfoGal13)GalNAc1OB 23. We herein report the synthesis of these two compounds and also that of other modified analogs that are highly specific acceptors for the two sulfotransferases. Appropriately protected 1-thio-glycosides 7, 8, and 10 were employed as glycosyl donors for the synthesis of our target compounds.     

Primary structure of alpha-globin chains from river buffalo (Bubalus bubalis L.) hemoglobins

Primary structure analysis of the four river buffalo -globin chains showed that haplotypes A and B differ from each other by a substitution at codon 64 that may encode Ala or Asn. The A haplotype encodes two -globin chains, ^I1 and ^II3, which differ at positions 129 and 131: ^I1 has 64 Ala, 129 Phe, 131 Asn; ^II3 has 64 Ala, 129 Leu, 131 Ser. The B haplotype encodes two -globin chains, ^I2 and ^II4, which differ at positions 10 and 11: ^I2 has 10 Ile, 11 Gln, 64 Asn; ^II4 has 10 Val, 11 Lys, 64 Asn. Apart from the Ala/Asn polymorphism at position 64, amino acid substitutions in allelic and nonallelic -globin chains seem to have arisen by single point mutations. Detection of electrophoretically silent mutations due to neutral amino acid substitutions and their influence on the isoelectric point are discussed. Furthermore, primary structures of river buffalo -globin chains are compared to other species of the Bovidae family to suggest evolutionary events that have characterized the amino acid substitutions of river buffalo hemoglobin.     

ERRATA

Page 685: For 2O% (•), 37% () and 47% (), read 2O% (),37% () and 47% (•) Page 695: For LDR and Relative growth data, move up columnsone line     

A novel lectin (morniga M) from mulberry (<Emphasis Type="Italic">Morus nigra</Emphasis>) bark recognizes oligomannosyl residues in N-Glycans

Morniga M is a jacalin-related and mannose-specific lectin isolated from the bark of the mulberry (Morus nigra). In order to understand the function and application of this novel lectin, the binding property of Morniga M was studied in detail using an enzyme-linked lectinosorbent assay and lectin-glycan inhibition assay with extended glycan/ligand collection. From the results, it was found that the di-, tri-, and oligomannosyl structural units of N-glycans such as those of the bovine ₁-acid glycoprotein (gp) and lactoferrin were the most active gps, but not the O-glycans or polysaccharides including mannan from yeast. The binding affinity of Morniga M for ligands can be ranked in decreasing order as follows: gps carrying multiple N-glycans with oligomannosyl residues >> N-glycopeptide with a single trimannosyl core > Tri-Man oligomer [Man1 6(Man 1 3) Man], Penta-Man oligomer [Man1 6(Man1 3)Man1 6(Man1 3) Man] Man 1 2, 3 or 6 Man > Man > GlcNAc, Glc >> L-Fuc, Gal, GalNAc (inactive), demonstrating the unique specificity of this lectin that may not only assist in our understanding of cell surface carbohydrate ligand-lectin recognition, but also provide informative guidelines for the application of this structural probe in biotechnological and clinical regimens, especially in the detection and purification of N-linked glycans.     

Die Hemmung der Phytochrominduzierten Photomorphogenese („Positive” Photomorphosen) des Senfkeimlings (Sinapis alba L.) Durch Actinomycin D und Puromycin

Zusammenfassung Die positiven Photomorphosen Öffnung des Hypokotylhakens und Entfaltung der Kotyledonen können ganz ähnlich wie die phytochrominduzierte Anthocyansynthese und andere positive Photomorphosen durch Actinomycin D und Puromycin gehemmt werden. Man kann daraus schließen, daß diese beiden photomorphogenetischen Reaktionen des Senfkeimlings ebenfalls durch eine von P₇₃₀ über eine Signalkette ausgelöste Aktivierung von potentiell aktiven Genen veranlaßt werden.

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The inhibition of phytochrome-mediated photomorphogenesis (positive photoresponses) by actinomycin D and puromycin in the mustard seedling (Sinapis alba L.)

Summary The many photochrome-mediated photoresponses of a seedling (Sinapis alba L., white seeded mustard) can be divided into 3 categories: positive, negative, and complex photoresponses. Positive photoresponses are those which are characterized by an initiation or a promotion of biosynthetic or growth processes (Mohr, 1966b). Phytochrome-mediated anthocyanin synthesis is the prototype of a positive photoresponse. It has been shown in previous papers (e.g. Lange and Mohr, 1965; Mohr et al., 1965) that positive photoresponses can be specifically inhibited by actinomycin D and puromycin. It has been concluded that in the case of positive photoresponses P₇₃₀ (the active phytochrome) exerts its function through differential gene activation.—In the present paper it has been demonstrated that phytochrome-mediated positive photoresponses of the mustard seedling like opening of the hypocotylar hook and unfolding of the cotyledons can be inhibited by relatively low doses of actinomycin D and puromycin in very much the same way as anthocyanin synthesis or cotyledon enlargement is inhibited. It has been concluded that in these cases too the action of P₇₃₀ must be attributed to an activation of potentially active genes in the manner postulated on the basis of the data on anthocyanin synthesis.

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Die Arbeit wurde durch Sachbeihilfen der Deutschen Forschungsgemeinschaft und der Stiftung Volkswagenwerk (an Prof. Mohr) ermöglicht.     

Suitability of different vegetation structure types as habitat for the whinchat (Saxicola rubetra)

In biocoenological investigations in grasslands of southwestern Germany vegetation structure types were distinguished by considering physiognomical characteristics. The mapping of these types formed the basis for the determination of habitat preferences of the whinchat. By comparing supply and demand for the various structure types the (relative) habitat preference could be quantified. There was a dependency of the habitat utilization on the density of available hunting perches, on the food supply and on the mowing dates of grassland. By assigning the structure types to the plant associations of the investigation area the spectrum of structure types within each plant association could be shown and the suitability of vegetation types for the whinchat delineated.Paper delivered: XIX Congress of the Gesellschaft für Ökologie (FRG), Osnabrück, FRG: 1989-10-9/12     

Structure guided design of a series of selective pyrrolopyrimidinone MARK inhibitors

The initial structure activity relationships around an isoindoline uHTS hit will be described. Information gleaned from ligand co-crystal structures allowed for rapid refinements in both MARK potency and kinase selectivity. These efforts allowed for the identification of a compound with properties suitable for use as an in vitro tool compound for validation studies on MARK as a viable target for Alzheimer’s disease.

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Nuclear and cytoplasmic gene control of resistance to loose smut (Ustilago tritici (Pers.) Rostr.) in wheat (Triticum aestivum L.)

Summary Using disomic chromosome substitution lines based on the susceptible wheat cultivar Chinese Spring, loose smut resistance of wheat cultivars Hope and Thatcher was shown to be conferred in each case by a single dominant major gene carried on chromosome 7 A (Hope) or 7 B (Thatcher). Partial resistance was determined by genes on an additional eight Hope or seven Thatcher chromosomes, and similarities were evident between the partial resistance genotypes ofHope and Thatcher. Chinese Spring exhibited a mean infection value of approximately 50%, indicating a significant level of partial resistance, which was found to be due, in part, to genes on the homoeologous chromosome arms 1 As, 1 Es and 1 Ds, and to cytoplasmic genes. Substitution of the Chinese Spring nucleus into the cytoplasm of Aegilops squarrosa, Ae. variabilis or Ae. mutica resulted in increased susceptibility to Ustilago tritici. Several alloplasmic lines of the resistant wheat cultivars Selkirk and Chris exhibited race-specific susceptibility to U. tritici.     

Diplosporous embryo-sac formation and the degree of diplospory inAllium tuberosum

Summary To obtain information on the dynamic and quantitative aspects of displospory in a facultative apomict,Allium tuberosum (2n = 32), we cytologically observed the entire course of female meiosis and embryosac development in cv Tender-Pole by the clearing-staining-squash method. A time-table of its course was constructed in terms of bud length and days pre-anthesis. Chromosome threads were observed in pairs at the earliest stage of meiosis, after which 32 autobivalents developed. Thus, endoreduplication must have occurred during premeiotic interphase or at the onset of female meiosis. Such endoreduplicational meiosis also occurred on the male side, though the frequency (3.9%) was much lower than that on the female side (80%). The degree of diplospory calculated as the percentage of reduplicated embryo-sac mother cells varied to some extent among six cultivars: Huhehaote and Manchuria showed the highest degree of diplospory (98%), and Kaohsiung the lowest (76%).     

Genotypic control of pollen plant formation in Nicotiana tabacum L.

Summary Tobacco plants (Nicotiana tabacum L.) of four varieties (Badischer Burley, White Burley, Techne, Kupchunos) were raised at different temperatures and daylengths and the effect of genotype on embryogenic pollen grain formation in situ and on pollen plant formation in anther and pollen cultures from these plants was studied. Genotype controlled embryogenic pollen grain and pollen plant formation by defining productivity under standard growth conditions (long days at 24 °C). Kupchunos was the most productive variety, followed by White Burley, Techne, and Badischer Burley. Furthermore, genotype defined which environmental factor was able to affect embryogenic pollen grain and pollen plant formation and also to which degree. In anther cultures, in addition to these effects, genotype controlled the formation of (an) inhibitory substance(s) in the anther wall in interaction with the plant growth conditions. In Badischer Burley and Techne, inhibitor action could be prevented by isolation of the pollen after one week of anther culture. Finally, direct pollen cultures in Badischer Burley and Techne produced embryos were only when the pollen was isolated from nearly mature anthers, while in White Burley and Kupchunos, embryos also produced at earlier stages and at higher yields. This indicated that genotype controls the time when the embryogenic pollen grains become ready to divide. The results are discussed in relation to strategies to overcome recalcitrance of species and genotypes.     

Confirmation of regional assignment of nucleoside phosphorylase (NP) on chromosome 14 by gene dosage studies

Summary Gene dosage studies yielded results consistent with assignment of the locus for nucleoside phosphorylase to band 14q13. The red blood cells from a patient with the karyotype 47,XX,+der(14),t(8;14)(8qter8q24: :14q2114pter)pat had enzyme activity 50% higher than red cells from 47 normal controls, two trisomies involving chromosomes other than 14, and five balanced translocations involving chromosome 14. On the other hand, the red cells of a case with a karyotype 45,XX,-14,-22,+der(22),t(14;22)(14qter14q11 or 14q12::22p1122qter)mat and a case with a karyotype 47,XX, +der(14),t(14;16)(14pter14q11::16q2416qter)mat had normal activity.