Improved predictive test for MEN2, using flanking dinucleotide repeats and RFLPs.

Gene(s) for the autosomal dominant endocrine cancer syndromes, multiple endocrine neoplasia type 2A (MEN2A), multiple endocrine neoplasia type 2B (MEN2B), and familial medullary thyroid carcinoma (MTC1) all map to the pericentromeric region of chromosome 10. Predictive testing for the inheritance of mutant alleles in individuals at risk for these disorders has been limited by the availability of highly informative and closely linked flanking markers. We describe the development of eight new markers, including two PCR-based dinucleotide repeat polymorphisms and six RFLPs that flank the disease loci. One of the dinucleotide repeat markers (sJRH-1) derives from the RBP3 locus on 10q11.2 and has a PIC of .88. The other dinucleotide repeat (sTCL-1) defines a new locus, D10S176, that maps by in situ hybridization to 10p11.2 and has a PIC of .68. We have constructed a new genetic linkage map of the pericentromeric region of chromosome 10, on the basis of 13 polymorphisms at six loci, which places the MEN2A locus between the dinucleotide repeat markers, with odds of 5,750:1 over the next most likely position. Using this set of markers, predictive genetic testing of 130 at-risk individuals from six families segregating MEN2A revealed that 95% were jointly informative with flanking markers, representing a significant improvement in genetic testing capabilities.     

Emerging role of lipids of Candida albicans, a pathogenic dimorphic yeast.

It is clear that C. albicans lipids have gained tremendous importance in recent years. In addition to being a barrier for entrance of various metabolites, it also provides the site of action for the synthesis of enzyme(s) involved in cell wall morphogenesis and antifungal action. While alterations in lipid composition during a yeast to mycelia transition have been observed, in most of the studies, lipid fluctuations reported could have been due to various environmental factors involved in the induction of morphogenesis [4,5]. A clear understanding of lipid biosynthesis and metabolic blocks due to antifungal action is likely to shed further light on selective interactions of antifungals. Despite the multifacet role of lipids in various functions of this pathogenic yeast, their exact involvement is poorly understood. The situation is little better with regard to ergosterol and its metabolism. Ergosterol is, indeed, important for anti-candidal activity and appears to be involved in the morphogenesis of C. albicans. The fluctuation in phospholipid composition have led to altered properties of plasma membrane namely, membrane fluidity, transport activities and drug sensitivity, which suggest that-a critical level of individual phospholipid is important for proper functioning of the plasma membrane. What the exact role is of individual phospholipid is far from clear. Many unanswered questions relating to the role of PI and sphingomyelin in signal transduction, involvement of phospholipases in the maintenance of phospholipid composition, and role of lipid transfer proteins in assembly and asymmetry of lipids are some aspects which merit further work.     

Characteristics and N-terminal amino acid sequence of a manganese peroxidase purified from Lentinula edodes cultures grown on a commercial wood substrate

Summary Extracellular culture filtrates from ligninolytic cultures of the lignin-degrading basidiomycete Lentinula (syn. Lentinus) edodes (Berk.) Pegler contained one major peroxidase when grown on a commercial oak-wood substrate. The peroxidase was purified by polyethylenimine clarification, anion-exchange chromatography, and hydrophobic-interaction HPLC. The enzyme (MnP1) was a heme-iron protein with an apparent molecular weight of 44 600 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and an isoelectric point of pH 3.2. The native enzyme had an absorption maximum at 407 nm, which shifted to 420 nm upon H₂O₂ addition. The pyridine-hemochrome-absorption spectrum indicated that one heme group was present per enzyme as protoporphyrin IX. N-terminal amino acid sequencing showed that MnP1 had higher sequence homology with manganese peroxidases than with lignin peroxidases reported from Phanerochaete chrysosporium. L. edodes MnP1 was capable of oxidizing lignin and lignin-model compounds in the presence of manganese and H₂O₂.On leave from the Department of Biochemistry, University of Otago, P. O. Box 56, Dunedin, New Zealand.Research carried out while a visiting scientist at the USDA Forest Products Laboratory from the National Chemistry Laboratory, Pune, India 41 1008 Offprint requests to: I. T. Forrester     

Calcium and magnesium induced changes in the relative fluidity of phosphatidylcholine liposomes

The effect of Ca²⁺ and Mg²⁺ on relative fluidity of phosphatidylcholine liposomes was studied by measuring the degree of chlorophyll fluorescence polarization. An increase in the degree of fluorescence polarization was observed on incubation of liposomes with different concentrations of Ca²⁺ or Mg²⁺. The results have been interpreted on the basis of increase in the size of liposomes which could be brought about by calcium or magnesium induced fusion of small unilamellar liposomes to form larger vesicles. Fusion of liposomes has also been confirmed by the experiments on efficiency of energy transfer from chlorophyll b to chlorophyll a, and transmission electron microscopy of liposomes before and after incubation with Ca²⁺ and Mg²⁺.     

Evaluation of three portable samplers for monitoring airborne fungi

Airborne fungi were monitored at five sample sites with the Burkard portable, the RCS Plus, and the SAS Super 90 air samplers; the Andersen 2-stage impactor was used for comparison. All samplers were calibrated before being used simultaneously to collect 100-liter samples at each site. The Andersen and Burkard samplers retrieved equivalent volumes of airborne fungi; the SAS Super 90 and RCS Plus measurements did not differ from each other but were significantly lower than those obtained with the Andersen or Burkard samplers. Total fungal counts correlated linearly with Cladosporium and Penicillium counts. Alternaria species, although present at all sites, did not correlate with total count or with amounts of any other fungal genera. Sampler and location significantly influenced fungal counts, but no interactions between samplers and locations were found.     

Fungal colonization of synthetic substrates for use in space craft

Summary Materials being used or considered for use in space flight were examined for their susceptibility to fungal colonization. The materials included soft goods (clothing) and insulation and fabrication products such as Velcro^® attachments and elastic cord binders. Materials were exposed for at least 28 days in a highhumidity chamber colonized with over 50 species of fungi, including those species recommended for determining recalcitrance of materials to fungal biodegradation. At least nine of 25 products demonstrated extensive microscopic colonization by fungi, mostly byAcremonium obclavatum. Challenge procedures that rely on observations with the unaided eye, or 40×magnification of growth by a restricted number of fungal species with a cellulosic substrate as a positive control, are insufficient for determining the resistance of synthetic substrates to fungal colonization.     

Biological, Serological and Coat Protein Properties of a Strain of Turnip Mosaic Virus Causing a Mosaic Disease of Brassica campestris and B. juncea in India

Biological, serological and coat protein properties of a potyvirus (Poty-Rape) causing a mosaic disease of Brassica campestris and B. juncea in India were investigated. The virus readily infected 4 of the 5 plant species in the family Brassicaceae in which it induced severe systemic mosaic symptoms; it also induced chlorotic and necrotic local lesions in Chenopodium amaranticolor , but failed to infect 4 other species of Chenopodiaceae or 20 species of Amaranthaceae, Apiaceae, Canabinaceae, Compositae, Cucurbitaceae, Euphorbiaceae, Leguminosae and Solanaceae. The virus was transmitted in a non-persistant manner by Myzus persicae, Brevicoryne brassicae and Aphis gossypii. The Average size, of the virus particles in a purified preparation was 740 nm × 12 nm. SDS-PAGE analysis of the viral coat protein showed two major bands of approximately 37 kDa and 31 kDa, a pattern very similar to that of a reference isolate of turnip mosaic virus (TuMV) from the U.S. In Western-blot immunoassay, an antiserum to TuMV reacted with both the coat protein bands of the Poty-Rape islate and the reference TuMV, but not with the coat proteins of four other potyviruses. The high performance liquid chromatographic profile of tryptic peptides from the coat protein of Poty-Rape was found to be very similar to that of the reference TuMV, but differed substantially from those of four other potyviruses. The Poty-Rape isolate is considered to be a distinct strain of, TuMV.     

Characterization of metabolically active developmental stage of Aspergillus niger cells immobilized in polyacrylamide gel

Summary The in-situ development of Aspergillus niger entrapped in polyacrylamide gel from spores and the gel surface characteristics were studied during the repeated shake flask batch citric acid fermentation. A marked increase in the rate of citric acid production was observed with the periodic replacement of culture with fresh media at an interval of 6 days reducing the fermentation time nearly to half. The metabolically active A. niger cells for citric acid production were characterized by the appearance of thick and bulbous hyphae scattered in and on the gel surface.