Absence of trichothecenes in toxigenic isolates of Fusarium moniliforme

Thirty-four isolates of Fusarium moniliforme were obtained from cereal grains collected in various parts of the world. The isolates were grown on rice and tested as a diet for toxicity to rats. Of these isolates, 53% caused death, 12% caused congestion and hemorrhage of the stomach and intestine as well as hematuria, 21% caused diarrhea, 38% caused weight loss, and 9% were nontoxic. The cultures were tested to T-2, HT-2, neosolaniol, acetyl-T-2, T-2-tetraol, iso-T-2, diacetoxyscirpenol, monoacetoxyscirpenol, deoxynivalenol, nivalenol, fusarenone-X, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, zearalenone, moniliformin, fusarochromanone, fusarin-C, and wortmannin; all were negative. In addition, F. moniliforme NRRL A25820 was grown on corn and banana fruit as solid substrates as well as on a defined liquid medium; none of the above toxins were found. When F. moniliforme NRRL A25820 was incorporated into a rat diet, no toxicity was noted. Twenty-eight additional isolates of F. moniliforme, isolated from feed associated with equine leukoencephalomalacia, were grown on cracked corn for 2 weeks. The cultures were negative when tested for deoxynivalenol, 15-acetyldeoxynivalenol, diacetoxyscirpenol, monoacetoxyscirpenol, nivalenol, and fusarenone X. Seventy-five percent of the isolates were toxic to ducklings, indicating the presence of a toxin other than trichothecenes. Our results support the conclusion that F. moniliforme does not produce trichothecenes.     

Ricin B chain fragments expressed inEscherichia coli are able to bind free galactose in contrast to the full length polypeptide

Deleted forms of ricin B chain (RTB) containing only one of the two galactose binding sites were produced inE. coli and targeted to the periplasm by fusion to theompA orompF signal sequences. The proteins were then isolated from the periplasm and their sugar binding properties assessed. Previous studies investigating the properties of such proteins produced inXenopus laevis oocytes suggested that deleted forms of RTB, when not glycosylated, retain their ability to bind simple sugars, unlike the full-length unglycosylated proteins. When produced inE. coli however we found that only one, EB733, of a number of deleted forms of RTB closely related to those previously produced inXenopus laevis oocytes, bound to simple sugars. All of the deletion forms of RTB were found to bind in the asialofetuin binding assay; an assay which has been previously utilized to measure binding of lectins to the terminal galactose residues of glycoprotein oligosaccharides. However, in contrast to glycosylated RTB, binding of the deletion mutants could be competed to only a small degree or not at all with galactose. The only deletion mutant observed to bind to free galactose when produced inE. coli corresponded closely to the complete domain 2 of RTB. It is assumed that this mutant forms a stable structure similar to that of the C-terminal domain in the full-length protein. The structural integrity of EB733 was not only suggested by its sugar binding properties and solubility but also by its consistently higher level of expression and the absence of any apparent susceptibility toE. coli proteases.Abbreviations RTA ricin toxin A chain - RTB ricin toxin B chain - ER endoplasmic reticulum - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis - IPTG isopropyl -d-thiogalactopyranoside     

Survey ofFusarium species in an arid environment of Bahrain

The prevalence and distribution of soil-inhabitingFusarium species in the soil of vegetable crops grown under custom-made plastic tunnels were studied at three geographical locations on the island of Bahrain. Six species ofFusarium representing a total of 1154 isolates were isolated on modified Komada medium. All species reported in this survey are recorded for the first time from the hot, arid desert of Bahrain.Fusarium solani andF. oxysporum were among the most frequently isolated fungi in all locations and crops.     

Salinity and hormone interactions in affecting growth,transpiration and ionic relations ofPhaseolus vulgaris

Addition of either abscisic acid (ABA) or kinetin at 10⁻⁶ M to salinized media (20–120mM NaCl) induced remarkable effects on growth ofPhaseolus vulgaris plants. Whereas ABA inhibited the plant growth and the rate of transpiration, kinetin induced stimulation of both parameters. Moreover, ABA increased proline and phosphorus concentrations in the salinized plants whilst kinetin decreased them. ABA induced stimulation of the transport of K, Ca and Cl from root to shoot, accumulation of K, Na and Cl in root cells and inhibits the transport of Na and accumulation of Ca. Kinetin appeared to inhibit the transport and accumulation of Na and Cl, transport of K, and stimulates the accumulation of K and Ca as well as the transport of Ca. The highest influence of both ABA and kinetin was mostly observed when these hormones were used in combination with the highest concentration of NaCl (120 mM) in the medium.     

Enhanced Expression of an Endothelin ETA Receptor in Capillaries from Human Glioblastoma: A Quantitative Receptor Autoradiographic Analysis Using a Radioluminographic Imaging Plate System

Abstract: We identified and characterized ¹²⁵I-endothelin-1 (¹²⁵I-ET-1) binding sites in tumor capillaries isolated from human glioblastomas, using the quantitative receptor autoradiographic technique with pellet sections. Quantification was done using the computerized radioluminographic imaging plate system. High-affinity ET receptors were localized in capillaries from glioblastomas and the surrounding brain tissues (K_D = 4.7 ± 1.0 × 10^?10 and 1.6 ± 0.3 × 10^?10M, respectively; B_max = 161 ± 38 and 140 ± 37 fmol/mg, respectively; mean ± SEM, n = 5). BQ-123, a selective antagonist for the ET_A receptor, potently competed for ¹²⁵I-ET-1 binding to sections of the microvessels with IC₅₀ values of 5.1 ± 0.3 and 5.1 ± 1.5 nM, and 10^?6M BQ-123 displaced 84 and 58% of ET binding to capillaries from tumors and brains, respectively. In addition, competition curves obtained in the presence of increasing concentrations of ET-3 showed two components (IC₅₀ = 5.7 ± 2.5 × 10^?10 and 1.4 ± 0.2 × 10^?6M for tumor microvessels, 1.8 ± 0.6 × 10^?10 and 1.1 ± 0.3 × 10^?6M for brain microvessels, respectively). Our results indicate that (a) the method we used is simple and highly sensitive for detecting and characterizing various receptors in tumor capillaries, especially in the case of a sparse specimen, and (b) capillaries in glioblastomas express specific high-affinity ET binding sites, candidates for biologically active ET receptors, which predominantly belong to the ET_A subtype.     

Analysis of γ-Aminobutyric AcidA Receptor Subunits in the Mouse Cochlea by Means of the Polymerase Chain Reaction

Abstract: Unlike 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which produces consistent decreases in levels of striatal dopamine (DA) with considerably smaller and more variable effects on mouse brain levels of serotonin (5-HT) and norepinephrine (NE), a novel amine-substituted MPTP analogue, 1-methyl-4-(2'-aminophenyl)-1,2,3,6-tetrahydropyridine (2'-NH₂-MPTP), administered in a standard mouse dosing paradigm for MPTP (20 mg/kg X 4) did not affect striatal DA but led to marked reductions (60–70%) in levels of 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), and NE measured in frontal cortex and hippocampus 1 week after treatment. Another 2'-substituted MPTP analogue, 1-methyl-4-(2'-methylphenyl)-1,2,3,6-tetrahydropyridine, affected cortical and hippocampal 5-HT, 5-HIAA, and NE only minimally, while markedly reducing the DA content in striatum (90%), thus indicating that the substituent (-NH₂ versus -CH₃) at the 2'position is important for the differential effects of these MPTP analogues. In a replication study with a 3-week end point, hippocampal and cortical 5-HT, 5-HIAA, and NE levels remained depressed with no indication of recovery. These results suggest that 2'-NH₂-MPTP may be a novel, regionally selective neurotoxin for serotonergic and norad-renergic nerve terminals.     

Effects of salinity on growth and metabolism ofPhaseolus vulgaris

Increasing salinity induced a marked reduction in the plant growth, thoughPhaseolus seedlings tolerated salinity up to 120 mM NaCI. A great reduction in sugar and protein contents occurred with increasing salinity, whereas soluble nitrogen compounds and the relative contents of the photosynthetic pigments were increased in the treated plants. Increasing Ca concentration in the salinized medium appeared to improve the plant growth and to increase the contents of saccharides and proteins in the NaCl-treated plants. This suggests that Ca could be added to salinized media to overcome the deleterious effects of salinity on the growth and productivity of leguminous crop plants.