Sequence analysis of the Aspergillus nidulans pectate lyase pelA gene and evidence for binding of promoter regions to CREA, a regulator of carbon catabolite repression.

The nucleic acid and deduced amino-acid sequences of the pectate lyase gene (pelA) from Aspergillus nidulans are presented. The pelA gene contains two short introns, 68 and 49 bp in length, and encodes a peptide of 326 amino acids. Five transcriptional start sites are clustered between 65 and 79 bp upstream of the start codon as determined by primer extension.

Percutaneous aspiration thromboembolectomy to manage the embolic complications of angioplasty and as an adjunct to thrombolysis.

Percutaneous aspiration thromboembolectomy (PAT) can be used to treat the embolic complications of angioplasty. The same technique is of value during thrombolysis to remove large pieces of thrombus. We report on our experience with PAT in 21 patients.

Molecular characterization of aflR, a regulatory locus for aflatoxin biosynthesis.

Aflatoxins belong to a family of decaketides that are produced as secondary metabolites by Aspergillus flavus and A. parasiticus. The aflatoxin biosynthetic pathway involves several enzymatic steps that appear to be regulated by the afl2 gene in A.

Case report: chronic osteomyelitis demonstrated by high resolution ultrasonography.

Ultrasound is a well established method of imaging for many systems of the body. The physical properties of bone do not usually lend themselves to ultrasonic investigation, due to the reflection of sound waves at a soft tissue/bone interface. However, the periosteum, early new bone formation and soft tissue changes alongside dense bone may be imaged.

A clearer view of singing voice production: 25 years of progress.

Voice research has enjoyed its most productive period of history during the past 25 years. Many of the enigmas related to the biomechanics and acoustics of the singing voice have been resolved. This paper presents state-of-the-art understanding regarding the following topics: vibrato, the singer's formant, formant tracking, voice registers, subglottal pressure, voice classification, modes of vocal fold vibration, laryngeal position during singing, flow glottography, and singing synthesis.

Report on the clinical workstation and clinical data repository utilization at UNC Hospitals.

On December 1, 1993, we implemented version 2.1 of the Clinical Workstation-Clinical Data Repository application in the Ambulatory Care Center. This version of the workstation allowed access of laboratory data from the clinical data repository that had been populated by a real-time HL7 interface between the Clinical Data Repository and the Laboratory Information System.

Living Maize Embryo Influences Accumulation of Aflatoxin in Maize Kernels.

Kernels from two maize populations, MAS:gk and MAS:pw,nf, showed significant postharvest resistance to aflatoxin contamination by Aspergillus flavus but showed no significant inter-population variation for this resistance. Growth of A. flavus on both populations was significantly less than on susceptible control lines.

Cloning and characterization of a cDNA from Aspergillus parasiticus encoding an O-methyltransferase involved in aflatoxin biosynthesis.

Aflatoxins are polyketide-derived secondary metabolites produced by the fungi Aspergillus flavus and Aspergillus parasiticus. Among the catalytic steps in the aflatoxin biosynthetic pathway, the conversion of sterigmatocystin to O-methylsterigmatocystin and the conversion of dihydrosterigmatocystin to dihydro-O-methylsterigmatocystin are catalyzed by an S-adenosylmethionine-dependent O-methyltransferase. A cDNA library was constructed by using RNA isolated from a 24-h-old culture of wild-type A.

Cloning of the Aspergillus parasiticus apa-2 gene associated with the regulation of aflatoxin biosynthesis.

An Aspergillus parasiticus gene, designated apa-2, was identified as a regulatory gene associated with aflatoxin biosynthesis. The apa-2 gene was cloned on the basis of overproduction of pathway intermediates following transformation of fungal strains with cosmid DNA containing the aflatoxin biosynthetic genes nor-1 and ver-1. Transformation of an O-methylsterigmatocystin-accumulating strain, A.

C(15)H(24) Volatile Compounds Unique to Aflatoxigenic Strains of Aspergillus flavus.

Headspace volatiles from eight strains of Aspergillus flavus (four aflatoxigenic strains and four nonaflatoxigenic strains), grown for 1, 2, 3, 4, 8, and 10 days in submerged cultures, were collected in Tenax GC traps. The traps were desorbed onto a 50-m gas-liquid chromatography capillary column by heat and gas purge from an external direct injector device. The column was interfaced with a mass spectrometer data acquisition system.

Purification of a 40-kilodalton methyltransferase active in the aflatoxin biosynthetic pathway.

The penultimate step in the aflatoxin biosynthetic pathway of the filamentous fungi Aspergillus flavus and A. parasiticus involves conversion of sterigmatocystin to O-methylsterigmatocystin. An S-adenosylmethionine-dependent methyltransferase that catalyzes this reaction was purified to homogeneity (> 90%) from 78-h-old mycelia of A.

Cloning of the afl-2 gene involved in aflatoxin biosynthesis from Aspergillus flavus.

Aflatoxins are extremely potent carcinogens produced by Aspergillus flavus and Aspergillus parasiticus. Cloning of genes in the aflatoxin pathway provides a specific approach to understanding the regulation of aflatoxin biosynthesis and, subsequently, to the control of aflatoxin contamination of food and feed. This paper reports the isolation of a gene involved in aflatoxin biosynthesis by complementation of an aflatoxin-nonproducing mutant with a wild-type genomic cosmid library of A.

Progress report on the clinical workstation and clinical data repository at UNC Hospitals.

In 1991, we demonstrated a prototype version of the Clinical Workstation at SCAMC. At the present time 48 workstations have been implemented in the ambulatory care areas of the Hospital. We describe the present functionality of the workstation and the work done to date on the clinical data repository.

Aflatoxin production via cross-feeding of pathway intermediates during cofermentation of aflatoxin pathway-blocked Aspergillus parasiticus mutants.

Cofermentation of Aspergillus parasiticus strains (SRRC 163 and SRRC 2043) blocked at different steps in the aflatoxin B1 (AFB1) biosynthetic pathway in a synthetic liquid medium or on seeds (cottonseed, corn kernels, and peanuts) resulted in production of AFB1. Strain SRRC 2043 accumulated O-methylsterigmatocystin (OMST), a late precursor in AFB1 biosynthesis, whereas SRRC 163 accumulated averantin, an early precursor in the pathway. Strain SRRC 2043 secreted large amounts of OMST in culture relative to the amounts of several other pathway intermediates secreted into media (by other AFB1 pathway-blocked strains).

Reduction in Aflatoxin Content of Maize by Atoxigenic Strains of Aspergillus flavus.

In field plot experiments, an atoxigenic strain of Aspergillus flavus interfered with preharvest aflatoxin contamination of corn when applied either simultaneously with or one day prior to a toxigenic strain. The atoxigenic strain reduced preharvest aflatoxin contamination 80 to 95%. The atoxigenic strain was also effective in reducing postharvest aflatoxin contamination caused by both an introduced toxigenic strain and by strains resident on the kernels.

Making the transition from information systems of the 1970s to medical information systems of the 1990s: the role of the physician's workstation.

Many hospitals today have implemented widely disparate information systems on mainframe and mini-computer hardware. The advent of network technology in hospitals has made it possible to access information in these systems. Unfortunately, the user interfaces to applications on these systems are unique and difficult to learn, which makes them unsuitable for use by clinical services.

Enzymological evidence for separate pathways for aflatoxin B1 and B2 biosynthesis.

Aflatoxins B1 (AFB1) and B2 (AFB2) are biologically active secondary metabolites of Aspergillus flavus and Aspergillus parasiticus. These toxins are synthesized by the fungi from pathway precursors: sterigmatocystin (ST)----O-methylsterigmatocystin (OMST)----AFB1; dihydrosterigmatocystin (DHST)----dihydro-O-methylsterigmatocystin (DHOMST)----AFB2. The late stages of AFB1 synthesis are carried out by two enzyme activities, a methyltransferase (MT) (ST----OMST), and an oxidoreductase (OR) (OMST----AFB1).

The Physician's Workstation: an example of end user integration of information systems.

Many hospitals today have implemented widely disparate information systems on mainframe and mini-computer hardware. The advent of network technology in hospitals has made it possible to access information in these systems. Unfortunately, the user interfaces to applications on these system are unique and difficult to learn, which makes them unsuitable for use by clinical services.

Variation in polygalacturonase production among Aspergillus flavus isolates.

Pectinase production by Aspergillus flavus was determined by measuring clear zones formed around colonies stained with ruthenium red. Several isolates produced red zones instead of clear zones. Red zones were reproduced with pectinesterase and correlated with absence of specific polygalacturonases.

Evidence for de novo synthesis of an aflatoxin pathway methyltransferase near the cessation of active growth and the onset of aflatoxin biosynthesis in Aspergillus parasiticus mycelia.

The accumulation of both activity and protein of a methyltransferase (MTase) from Aspergillus parasiticus, which catalyzes conversion of sterigmatocystin to O-methylsterigmatocystin in the aflatoxin pathway, was detected in fungal mycelia slightly before the onset of aflatoxin biosynthesis in the same cultures. MTase protein was identified in mycelial postmicrosomal (soluble protein) fractions by electrophoresis and subsequent immunoblotting using antiserum raised against purified MTase protein; MTase activity was determined by measuring the rate of conversion of sterigmatocystin to O-methylsterigmatocystin in the presence of soluble protein fractions. Using the above technique, it was determined that MTase protein as well as MTase activity increased sharply in mycelia 30 to 45 h after inoculation, shortly after which, mycelial growth rate began to decline.

Enzymes in aflatoxin B1 biosynthesis: strategies for identifying pertinent genes.

Recent work on the aflatoxin biosynthetic pathway is reviewed, with special emphasis on the enzymes of the late stages of the pathway involving conversion of sterigmatocystin (ST) to aflatoxin B1 (AFB1) through an O-methylsterigmatocystin intermediate. Two enzyme activities were discovered in subcellular fractions of cell-free extracts of a mutant strain of Aspergillus parasiticus (SRRC 163): 1) A post-microsomal methyltransferase (MT) catalyzed conversion of ST to OMST, and 2) a microsomal-associated activity (oxido-reductase) converted OMST to AFB1. The 168 KDa, anionic MT was purified to homogeneity and characterized (two subunits, 110 KDa and 58 KDa).

Comparison of the enzymatic composition of cell-free extracts of non-aflatoxigenic Aspergillus parasiticus with respect to late stages of aflatoxin biosynthesis.

Cell-free extracts of fungal mycelia of two non-aflatoxigenic isolates of Aspergillus parasiticus (SRRC 163 and SRRC 2043) were examined for enzyme activities involved in the latter stages of aflatoxin biosynthesis. Post-microsomal fractions (105 Kxg supernatant) of both SRRC 163 (ATTC 56774) and SRRC 2043 were able to convert sterigmatocystin (ST) to O-methylsterigmatocystin (OMST); whereas the microsomal (105 Kxg pellet) preparation of only SRRC 163 was able to convert OMST to aflatoxin B1 (AFB1). A mixture of the microsomal fraction of SRRC 163 and post-microsomal fraction of SRRC 2043 converted ST to AFB1.

Conversion of dihydro-O-methylsterigmatocystin to aflatoxin B2 by Aspergillus parasiticus.

Dihydro-O-methylsterigmatocystin (DHOMST) was identified in cultures of Aspergillus parasiticus SRRC 2043, an aflatoxin (AF) non-producer, by comparison of its mass spectrum to that of authentic DHOMST. In addition to DHOMST, SRRC 2043 is known to produce two other chemically related compounds in culture: O-methylsterigmatocystin (OMST) which is an AFB1 precursor and a hydrated-vinyl ether analogue of OMST (HOMST) which is an AFB2 precursor. In the present study, DHOMST also was shown to be an AFB2 precursor by demonstrating that DHOMST is converted to AFB2 by mycelia of an A.

Fate of the methyl group during the conversion of sterigmatocystin into O-methylsterigmatocystin and aflatoxin B1 by cell-free preparations of Aspergillus parasiticus.

Cell-free extracts of fungal mycelia of two aflatoxin non-producing isolates of Aspergillus parasiticus (SRRC 163 and SRRC 2043) were utilized for the study of enzyme activities involved in the latter stages of aflatoxin biosynthesis. The post-microsomal fractions (105,000 x g supernatant) of both SRRC 163 and SRRC 2043 were able to convert sterigmatocystin (ST) into O-methylsterigmatocystin (OMST); whereas the microsomal (105,000 x g pellet) preparation of only SRRC 163 was able to convert OMST into aflatoxin B1 (AFB1). S-Adenosylmethionine (SAM) was the primary substrate for the ST to OMST (methyltransferase) enzymatic conversion; [3H]OMST of specific activity 0.