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The production of enniatin is not needed for the infection of potato tuber tissue by the Fusarium species, but is required for the pathogenicity of the enniatin producing strains. Enniatin is a phytotoxin that causes necrosis in potato tuber tissues. The toxicity of Fusarium strains on the potato tuber tissue is analyzed by assaying the virulence on the tissue as enniatins stimulate necrosis of potato tissues in vitro.

Several group 1 strains of Pseudomonas (P.) syringae pv. tomato and strain 4981 of P. syringae pv. maculicola have the genes for coronatine on a plasmid, while group 2 strains of P. syringae pv. maculicola and tomato tend to have the genes on chromosomes. Researchers analyzed the DNA that produces the plant toxin coronatine in 22 strains of P. syringae. Although the genes were conserved among the different strains, there were differences between those that appeared on plasmids and those that appeared on chromosomes.

A study of the position of the toxic border of Bacillus thuringiensis protoxin and the role of the non-toxic domain of the protein for active toxin production in vivo by introducing sequential termination codons reveals that mutations that code for the 606 aa and beyond are more toxic, while the mutations that code for 605 aa or less are non-toxic, indicating that the 606 position localizes the critical residue. Analysis of the toxicity of the extracts and the quantity of proteins in the immuno-precipitates indicates that the activity of the mutants is similar to that of the intact protein. Inclusion bodies formed from gene products of the intact protoxin are active and soluble in alkali, while such bodies from the mutants are inactive and insoluble.

Several enzymes catalyze the biosynthesis of tentoxin by Alternaria alternata, which occurs through a thiotemplate mechanism, similar to that in various cyclic peptides. Sections of mycelial mats incubated in buffer aid this physiological study. The growth of tentoxin is rapid between 9 and 12 days from the start of the synthesis. There is an enhancement in the rate of tentoxin release from the cells at pH values more or less than 7. This synthesis is aided by precursor amino acids.

Microcystins are cyclic heptapeptide hepatotoxins of algal blooms. The variation in microcystins isolated from 13 Finnish Oscillatoria agardhii strains were investigated. The 13 strains yielded eight different microcystins, of which five were previously known and three were new. The structure of one of the new microcystins was determined to be an Mser variant of MCYST-RR, and is possibly a biosynthetic precursor of the principal toxin.

Recombination of two delta-toxins from Bacillus thuringiensis, CryIAa and CryIAc, by reciprocal exchange of specificity regions resulted in proteins susceptible to proteolyticcleavage and reduced insecticidal potency. The instability of the recombinant toxin structure can be suppressed by introducing a second mutation in defined regions of the gene for the original recombinant CryIAa gene.

The activation and activation of aerolysin from the protoxin form were analyzed using several spectroscopic techniques. The sites for trypsin and chymotrypsin cleavage were identified. Trypsin-mediated proteolytic modification does not produce appreciable alteration in the toxin's secondary or tertiary conformation, however, there is an alteration in the spatial orientation of tryptophan residues due to the exposure of a hydrophobic region. The oligomerization of aerolysin molecules activated by trypsin was also investigated.

The in vivo binding of the 51 and 42 kDa proteins of Bacillus sphaericus strain 2297 to the gut of the mosquito Culex quinquefasciatus larvae were investigated. The glutathione S-transferase fusion protein purification system was used for the expression in Escherichia coli of the toxin proteins and their NH2- and COOH-terminal deletion derivatives. The results suggested that the 51 kDa protein is the binding component of the binary toxin of B. sphaericus, and that the NH2-terminal region of P51 is required in the binding step, while the COOH-terminal region is involved in interacting with P42. Moreover, there was a strong correlation between toxicity and internalization of the toxin.

The environmental expression of sulfur compound disproportionation has been placed between 640 and 1050 million years ago (Ma) and linked to increases in atmospheric oxygen. These arguments have their basis in temporal changes in the magnitude of [sup.34]S/[sp.32]S fractionations between sulfate and sulfide. Here, we present a Proterozoic seawater sulfate isotope record that includes the less abundant sulfur isotope 33S. These measurements imply that sulfur compound disproportionation was an active part of the sulfur cycle by 1300 F4a and that progressive Earth surface oxygenation may have characterized the Mesoproterozoic., There is a strong link between the oxidation state of the Earth's surface environment and the microbial sulfur metabolisms that influence the sulfur cycle (1-3). This link is revealed through [...]

Research was conducted to examine the effect of aromatic compounds on cellular fatty acid composition of Rhodococcus opacus. The contents of branched fatty acids increased from 3% to 15 to 34% of the total fatty acids in Rhodococcus opacus cells when the cells were developed on phenol, tolune, chlorobenzene, benzene and 4-chlorophenol as the sole source of energy and carbon. Results indicate that 10-methyl branched fatty acids may play a role in the adaptation of R. opacus to lipophilic aromatic compounds.

Examination of the decomposition of ochratoxin A (OTA) as a function of temperature and moisture reveals that decomposition of OTA at 100 and 150 degrees Celsius is favored by the presence of water, while at 200 degrees Celsius, presence of water inhibits the decomposition. Temperatures between 100 and 250 degrees Celsius fail to perform the complete decomposition of OTA.

Chromatographic techniques helps isolate a cytotoxic metabolite, talarotoxin, from Talaromyces bacillosporus IFO 8397, cultured on rice. Spectroscopic study of the structure of the toxin reveals that a conjugated triene connects a pyrrolizidinedione to a trans-Delta 1-octalin. Intraperitoneal administration of the toxin leads to breathing problem in mice.

A number of bacterial protein toxins, including adenylate cyclase (AC) toxin from Bordetella pertussis, require the product of an accessory gene in order to express their biological activities. In this study, mass spectrometry was used to demonstrate that activated, wild-type AC toxin was modified by amide-linked palmitoylation on the E-amino group of lysine 983. This modification was absent from a mutant in which the accessory gene had been disrupted. A synthetic palmitoylated peptide corresponding to the tryptic fragment (glutamine 972 to arginine 984) that contained the acylation blocked AC toxin-induced accumulation of adenosine 3',5'-monophosphate, whereas the nonacylated peptide had no effect., Adenylate cyclase toxin is a virulence factor from Bordetella pertussis, the bacterium that causes pertussis or 'whooping cough.' This disease is responsible for an estimated 340,000 deaths per year, largely [...]

High-pressure liquid chromatography (HPLC) and thin-layer chromatography (TLC) techniques reveal that Aspergillus niger var. niger generates ochratoxin A (OA) in 2% yeast extracts, 15% sucrose broth and corn cultures. OA production contaminates food products and hinders enzyme preparations, resulting in animal and human death hazards.

The cloning and expression of two crystal protein genes, cry44Aalorf2-44A and cry30Balorf2-30B was reported from Bacillus thuringiensis subsp. entomocidus INA288. These studies serve as evidence that genes from INA288, such as cry44Aalorf2-44A is useful in managing resistance and as a component of synthetic combinations of mosquitocidal toxins.

Cry1Ab toxin binding analysis was conducted to find out if altered binding is associated with Cry1Ab resistance in selected Ostrinia (O.) nubillalis strains. The results show that differences in susceptibility to Cry1A toxins in Europe-R strain of O. nubilalis are associated with altered receptor binding, though the exact nature of this mechanism is unclear.

Produce isolates of the Escherichia coli Ont:H52 serotype carried Shiga toxin 1 and stable toxin genes but only expressed Stx1. The Ont:H52 strains shares similar pulsed-field gel electrophoresis profiles and an identical but distinctive sequence type, indicating that they are a unique Shiga-toxigenic Escherichia coli (STEC) clonal group.

The effect of Cry proteins off Bacillus thuringiensis on the green lacewing (Chrysoperla carnea) was studied in which lacewing larvae were fed Cry1Ac toxins and tested to see whether specific binding of Cry toxin to the epithelial cells of the midgut took place. It was concluded that there were no detrimental effects of the bacillus cry toxins on the green lacewing when they are ingested either directly or through the prey.

A toxin gene Txp40 was identified in Xenorhabdus and Photorhabdus, which is lethal to the larvae of insects such as Helicoverpa armigera. Histological data from H. armigera larvae into which the toxin was injected suggested that the primary site of action of the toxin is the midgut although some damage to the fat body was also observed.

The Vero cell cytotoxicity assays, enzyme immunoassays (EIA), latex agglutination (LA), and colony immunoblot assays to characterize Shiga toxin (Stx) production in non-O157 Escherichia coli clinical isolates possess an stx(sub 2) variant as their sole stx gene. It is concluded that six of 37 non-O157 Esherichia coli strains possessing stx 2 gene variant stx(sub 2d) or stx(sub 2e) secreted no detectable Stx.

A survey is conducted to identify the presence of a single C. perfringens isolate carrying the enterotoxin gene necessary for causing food poisoning. The findings indicate that some American foods are contaminated at the time of retail purchases, with C. perfringens isolates having full potential to cause food poisoning.

Many emerging and reemerging bacterial pathogens synthesize toxins that serve as primary virulence factors. We highlight seven bacterial toxins produced by well-established or newly emergent pathogenic microbes. These toxins, which [...]

In this issue, Kuehne and colleagues (1) show that the pathogenic bacterium Clostridium difficile can cause disease using either of its two main toxins--toxin A and toxin B. These findings [...]

Enhancement of Symbiotic Dinitrogen Fixation by a Toxin-Releasing Plant Pathogen WE HAVE OBSERVED AN UNUSUAL and highly beneficial infestation of nodulating alfalfa plants by a toxin-releasing Pseudomonas (Fig. 1). Infestation [...]

Three-Dimensional Structure of Cholera Toxin Penetrating a Lipid Membrane MANY POLYPEPTIDE TOXINS AND GLYCOPROTEIN HORmones are composed of two types of chain, one (B) which binds a cell surface receptor, [...]

Pertussis Toxin Gene: Nucleotide Sequence and Genetic Organization PERTUSSIS TOXIN (1) IS ONE OF THE various toxic components produced by virulent Bordetella pertussis, the microorganism that causes whooping cough. A [...]

A study was conducted to determine bacterial strains that facilitate emetic toxin production. Bacterial strains of Baccilus cereus, Baccillus anthracis, Bacillus licheniformis, Baccillus mycoides, Bacillus subtilis, Bacillus thuringiensis, Brevibacillus agri, Paenibacillus macerans and Paenibacillus polymyxa were evaluated. Results indicate that only strains of Bacillus cereus exhibit cytotoxicity.

A 16-step synthetic sequence enables the total synthesis of ACRL toxin IIIb with an yield of four percent. This method is applicable for preparing compounds with three stereocenters having a (n, n+1, n+4) relationship. The advantage of this method is that it can use either a syn or anti aldol as precursor and utilizes either the Z or E enolate in the Ireland ester enolate Claisen rearrangement.

The isolation and structural characterization of cylindrospermopsin, an alkaloid derived from the cyanobacterium Cylindrospermopsis raciborskii, is presented. An aqueous extract of the ultrasonicated, freeze-dried C. raciborskii is fractionated by gel filtration to give the compound C15H21N5O7S. Structural assignment is performed by analysis of the 500-MHz 1H and 125-MHz 13 C NMR spectra in D2O and via two-dimensional COSY, HMQC and HMBC experiments.

Research was conducted to examine the hypothesis that alpha-Bungarotoxin (Bgt) receptors contain alpha-7 subunits in two different disulfide-bonded conformations. The alpha-7 receptors were compared with Bgt-binding receptors which revealed differences in processing. Results indicate that two different alpha-7 subunit conformations in a receptor are necessary for receptor function. Findings also suggest that alpha-7 subunit diversity can be achieved postranslationally.

Energy Dept researchers at the Los Alamos National Laboratory have developed a method for detecting the cholera-causing toxin that should be equally applicable in the detection of other protein-based toxins including those that could be used in bio-terrorism or bio-warfare. The technique replicates nature cell-signalling mechanisms and is highly sensitive, produces results quickly and can select specific proteins from a sea of background molecules., Department of Energy researchers at the Los Alamos National Laboratory have developed a technique for detecting the toxin that causes cholera. The technique should work equally well in detecting other [...]