Effects of Fusarium graminearum Metabolites on Wheat Tissue in Relation to Fusarium Head Blight Resistance

Fusarium head blight (FHB) of wheat is caused by Fusarium graminearum which produces many secondary metabolites including the trichothecene mycotoxins deoxynivalenol (vomitoxin) and 3-acetyldeoxynivalenol. Coleoptile tissue segements from 14 spring wheat cultivars were exposed to the F. graminearum metabolites deoxynivalenol, 3-acetyldeoxynivalenol, butenolide (all known mycotoxins), sambucinol, culmorin and dihydroxycalonectrin in a bioassay. The tissue of most cultivars was inhibited, at a concentration of 10^?6M by the trichothecenes tested and up to 10^?3M for the other compounds. Deoxynivalenol and 3-acetyldeoxynivalenol, which affect protein synthesis at the ribosome, are therefore potent phytotoxins in addition to being mycotoxins. The resistance or susceptibility of each cultivar to FHB was established in a field experiment. A comparison of the two sets of data indicated that resistant cultivars could tolerate much higher concentrations of the metabolites tested than susceptible cultivars. Some resistant material can tolerate 10 to 1000 times the concentration of the trichothecenes, compared with susceptible cultivars, with no effect on growth. The data suggest that it may be possible to screen germplasm rapidly for FHB resistance in vitro and a new type of resistance in wheat to this disease is proposed based on the apparent insensitivity to trichothecenes by resistant cultivars, additional to the three types of resistance described in the literature.     

The effects of low levels of chloramphenicol and methotrexate on somatic embryogenesis inCitrus

Summary The effects of the antibiotics methotrexate and chloramphenicol on somatic embryogenesis inCitrus were evaluated. Relatively low levels (0.1 to 1.0 μg/ml) of these antibiotics did not inhibit embryo production from undeveloped ovules of ‘Key’ lime [C. aurantifolia) (Christm.) Swing.]. Surprisingly, both antibiotics induced the formation of embryogenic callus in these cultures. This is usually a rare event in cultures of undevelopedCitrus ovules, and ‘Key’ lime is especially recalcitrant. The effects of these antibiotics on embryogenic callus appeared to be limited to the induction stage, because there was no consistent effect, either stimulatory or inhibitory, on established, lines of embryogenic callus. Florida Agricultural Experiment Station Journal Series No. 8958. This research was supported in part by a grant to Moore and Cline from the Competitive Grants Office of the SEA, USDA (85-CRCR-1-1623).     

Optimal alignments in linear space

Space, not time, is often the limiting factor when computingoptimal sequence alignments, and a number of recent papers inthe biology literature have proposed space-saving strategies.However, a 1975 computer science paper by Hirschberg presenteda method that is superior to the new proposals, both in theoryand in practice. The goal of this paper is to give Hirschberg'sidea the visibility it deserves by developing a linear-spaceversion of Gotoh's algorithm, which accommodates affine gappenalties. A portable C-software package implementing this algorithmis available on the BIONET free of charge. Received on October 14, 1987; accepted on December 19, 1987     

Measurement of magnetically induced electric fields in conductive media near a 60 Hz current-carrying wire.

Electric fields induced in a conductive body by the magnetic field of a current-carrying wire were analyzed theoretically and experimentally to assess the dosimetric importance of highly nonuniform, field-exposure conditions. Experimentation revealed that a 60-Hz magnetic field was inversely proportional to the radius of a wire bundle carrying 100 A within a 0.5-m2 test area. A miniaturized electric field probe was used to measure the electric fields induced in 5-cm-deep, saline-filled models. In the theoretical analysis, numerical estimates of induced fields were made by a spreadsheet method. The theoretical calculations and the measured values of induced electric fields were generally in good agreement. The induced fields were in a plane perpendicular to a vertically incident magnetic field; the maximally induced fields were in areas nearest the wire bundle. The strength of the induced field increased with model size: from 96 microV/cm in a 10 x 10 cm model to 176 microV/cm in a 40 x 40 cm model. The strength of the field induced in a 20 x 20 cm model decreased with increasing model-to-wire spacing: from 132 microV/cm for a 1-cm spacing (2-mT maximum, incident field) to 50 microV/cm for a 6-cm spacing (0.33-mT maximum). The results indicate that increases in local values of nonuniformly incident fields produce relatively small increases in induced electric fields. This finding may be important in dosimetric consideration of circumstances, such as use of electric blankets, in which fields of low average strength are accompanied by intense local fields.     

Immunological evidence for a conformational difference between recombinant bovine rhodanese and rhodanese purified from bovine liver

Rhodanese has been utilized as a model enzyme for the study of protein structure-function relationships. The enzyme has recently been cloned and the recombinant enzyme is now available for investigation. However, prior to use in structure-function studies, the recombinant enzyme must be shown to have the same structure and activity as the bovine liver enzyme used in the previous studies. An immunological study of the conformations of these enzyme conformers is described. Three antibodies (two monoclonal and one polyclonal, site-directed antibody) were shown to detect distinct and nonoverlapping epitopes. The epitopes of the monoclonal antirhodanese antibodies (R207 and MAB11) were mapped to the same CNBr digest fragment of the amino terminal domain of rhodanese, and the epitope of the site-directed antibody prepared against the interdomain tether sequence of rhodanese (PAT-T1) was mapped to that region of rhodanese (residues 142–156). The rhodanese conformers were studied by monitoring the accessibility of the epitopes recognized by each antibody in each conformer using an indirect ELISA. None of the antibodies could detect its epitope on the purified liver enzyme. Two of the antibodies (R207 and PAT-T1) could also not detect their epitopes on the recombinant enzyme. However, MAB11 did detect a conformational difference between the natural and recombinant rhodanese conformers, indicating the conformational difference is localized in the first 73 amino acids of rhodanese. This difference presumably reflects the difference in the histories of the two enzymes and may be due to differences in enzyme folding, differences in the purification procedures, and differences in storage conditions—all of which could influence the final conformation of the enzyme.     

Development of captive bongos (Tragelaphus eurycerus): Activity budgets and developmental milestones

The development of changes in visual orientation, posture, activity budgets, and behavioral milestones was examined in five bongo calves which were observed from birth to 4 or 6 months of age. The only significant change in the calves' visual orientation was an increase in orientation to food. Reclining declined significantly over weeks, while standing increased and moving did not change. Overall, stationary behaviors dominated the activity budget, but decreased significantly over the study. The category that included locomotion, object exploration, and auto-play did not change, while forage and rumination increased significantly. Contrary to expectation, the decline in suckling was not significant. Affiliative interactions with the dam decreased significantly during the study, but increases in affiliation with other bongos were not significant. Levels of agonistic behavior between the calves and their dams and other herd members were low throughout the study, and did not change significantly. One female calf achieved several developmental milestones later than the others. It is suggested that these differences may have been influenced by the dominance status of her dam. The results conform to the general developmental pattern of “hider” bovids. Bongos, however, show somewhat different patterns of social development than eland, which are reported to be more precocial in expression of aggressive and sexual behaviors. © 1992 Wiley-Liss, Inc.     

Effects of the stereochemical orientation of phenethylamines and imidazolines on alpha-adrenergic receptor-mediated DNA synthesis in primary cultured rat hepatocytes.

The hepatic alpha 1-adrenergic receptor mediates a variety of hepatic functions including respiration, glycogenolysis, gluconeogenesis, and growth. We have utilized a rat primary hepatocyte culture system to show that the alpha 1-adrenergic receptor can be activated in a stereoselective manner by a series of phenethylamines and catecholimidazolines resulting in the stimulation of DNA synthesis as determined by [3H]thymidine incorporation. The phenethylamines adhered to the Easson-Stedman hypothesis with a rank order of potency of (-)-(R)-norepinephrine (NE) greater than (+)-(S)-NE greater than the desoxy analog dopamine (DA) for the stimulation of DNA synthesis. However, the 2-substituted catecholimidazolines did not follow this trend and demonstrated an order of potency of the desoxy analog 3,4-dihydroxybenzyl imidazoline (DHT) greater than or equal to (-)-(R)-2-(3,4,alpha-trihydroxybenzyl)imidazoline (TBI) greater than (+)-(S)-TBI. 4-Substituted catecholimidazolines were less potent as inducers of DNA synthesis than the corresponding 2-substituted analogs with an order of potency of (+)-(R)-4-(3,4-dihydroxybenzyl)imidazoline (DBI) greater than (+,-)-(R,S)-DBI greater than (-)-(S)-DBI. When the beta-hydroxyl moiety of NE is replaced with an amino group as in 3,4-dihydroxyphenylethylenediamine, the isomers are less active than the beta-hydroxylated analogs and also demonstrate no stereoselectivity for the stimulation of DNA synthesis. These results demonstrate that the hepatic alpha 1-adrenergic receptor can recognize various isomeric forms of these compounds and that hepatocellular growth can be modulated in a stereoselective manner by phenethylamines and imidazolines.     

Localization of the amphotropic murine leukemia virus receptor gene to the pericentromeric region of human chromosome 8.

The host range of retroviruses is determined primarily by the presence of specific receptors on target cells which are recognized by the retroviral envelope glycoprotein. Somatic cell hybrids have been used to determine the chromosomal locations of several retroviral receptors in mice prior to their molecular cloning. Here we report that by using human-Chinese hamster somatic cell hybrids and a retroviral vector, we have mapped the receptor for the amphotropic murine leukemia virus to the pericentromeric region of human chromosome 8.     

Inhalational administration of cocaine in sheep

A pipe for administration of inhaled cocaine and its pyrolytic products in laboratory animals was developed and tested. In-vitro trials showed 30.0 +/- 5.2% (mean +/- SE) recovery of cocaine in solvent. Five non-pregnant ewes were instrumented with tracheal T-tubes and vascular catheters. After surgical recovery, ewes received three doses of cocaine (free base) in a randomized fashion; 2 mg/kg and 4 mg/kg both by inhalation, and 2 mg/kg intravenously. Arterial blood samples were collected and assayed for cocaine and its major metabolites by high performance liquid chromatography. Blood pressure and heart rate were continuously recorded. Cocaine administered by inhalation was eliminated with a half-life of 1.6 +/- 0.5 min (mean +/- SE) compared to 3.4 +/- 0.9 following intravenous administration (p less than 0.03). Likewise, clearance values were greater following inhalation, 5532 +/- 1756 ml/min/kg, than following intravenous administration, 163 +/- 20.6 ml/min/kg (p less than 0.04). Both routes of administration led to significant elevations in blood pressure, 7.5% increase after smoking vs 20% increase after intravenous administration. No correlation was found between inhalational dose of cocaine and peak plasma cocaine concentration.