Demonstration of Adventitious Sporulation in Fusarium Petroliphilum Onychomycosis

Mycopathologia - Fusarium petroliphilum is a recently described species within the Fusarium solani species complex. Some strains of Fusarium species are capable of forming yeast-like structures in...     

The recent evolutionary origin of the phenylalanine-sensitive isozyme of 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase in the enteric lineage of bacteria

Summary Evolutionary events that generated the three regulatory isozymes of 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase present in contemporary strains ofEscherichia coli have been proposed recently [Ahmad et al. (1986) J Bacteriol 165:146–154]. The phylogenetic subdivision of gram-negative prokaryotes studied (Superfamily B) includes enteric bacteria, anOceanospirillum cluster, pseudomonad Group I (e.g.,Pseudomonas aeruginosa), pseudomonad Group V (e.g.,Xanthomonas), and theAcinetobacter grouping. DAHP synthase-phe, a regulatory isozyme subject to allosteric control byl-phenylalanine, was the last member of the isozyme family to evolve. Thus, DAHP synthase-phe is absent throughout Superfamily B except within the enteric lineage. Bacteria that make up the enteric lineage (Escherichia, Klebsiella, Erwinia, Serratia, Proteus, Aeromonas, andAlteromonas) were examined in detail; DAHP synthasephe was present in each of these organisms. Therefore, the isozyme originated between the separation of the enteric andOceanospirillum lineages, prior to the divergence ofAlteromonas putrefaciens (44% homology withE. coli by DNA:rRNA hybridization) from the rest of the enteric lineage. DAHP synthase-tyr and DAHP synthase-trp were uniformly present within the enteric lineage, although it was often necessary to derepress DAHP synthase-trp by physiological manipulation in order to demonstrate its presence.     

The stable phylogenetic distribution of the recently evolvedl-phenylalanine-inhibited isozyme of 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase in enteric bacteria

Escherichia coli and some other enteric bacteria possess three regulatory isozymes of 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase, each of which is inhibited by one aromatic amino acid. Thel-phenylalanine-sensitive isozyme of DAHP synthase has evolved most recently since it is absent in all other members of the Gram-negative cluster that contains enteric bacteria as a subcluster. A comprehensive survey of enteric genera was carried out to determine whether the newly evolved isozyme is a stable, conserved trait. The results obtained show that all the genera of the contemporaryEnterobacteriaceae family possess the recently evolved phenylalanine-sensitive isozyme in addition to the tyrosine-and tryptophansensitive isozymes of DAHP synthase. However, physiological manipulation was usually necessary to derepress the tryptophan-sensitive DAHP synthase in order to demonstrate its presence.Florida Experiment Station Journal Series No. 9603.     

<Emphasis Type="Italic">Actinomucor elegans</Emphasis> var. <Emphasis Type="Italic">kuwaitiensis</Emphasis> isolated from the wound of a diabetic patient

The new variety of Actinomucor elegans var. kuwaitiensis, isolated from an open necrotic wound of a diabetic patient is described. This strain differed from the two previously described varieties of A. elegans, A. elegans var. elegans and A. elegans var. meitauzae by nearly 1% or more sequence divergence within D1/D2 regions of 28S rRNA and the ITS region of rRNA genes. Like the other two varieties, no zygospores were observed, however, there was evidence suggesting intersexual diploidy, a feature not described previously in this species. Additionally, A. elegans var. kuwaitiensis was pathogenic to white mice causing 100% mortality within 5 days.     

A role for plant natriuretic peptide immuno-analogues in NaCl- and drought-stress responses

Higher plants contain biologically active molecules that are recognized by anti-human atrial natriuretic polypeptide rabbit serum (anti-ANP). These molecules are termed immunoreactant plant natriuretic peptides (irPNPs) and have previously been shown to be associated with conductive tissue and to affect ion fluxes, protoplast volume regulation and stomatal guard cell responses. Herein an irPNP from the brassicaceus weed Erucastrum strigosum is identified and it is demonstrated that the relative amounts of irPNP expressed as a percentage of total water : methanol (50 : 50) extracted proteins are increased when plants are exposed to 300 m M NaCl. Since 100 and 200 m M NaCl reduce dry and fresh mass as well as increase total tissue NaCl load, it is hypothesized that irPNP up-regulation is a late and possibly adaptive response. IrPNP is also significantly up-regulated in Arabidopsis thaliana suspension culture cells in response to 150 m M NaCl and even more so in response to iso-osmolar amounts of sorbitol. Finally, a recombinant A. thaliana irPNP (AtPNP-A) promotes net water-uptake into the protoplast and thus volume increases. This response is dependent on de novo protein synthesis and may suggest a complex and possibly regulatory function for irPNP-like molecules in plant homeostasis.     

The role of sequence and structure in protein folding kinetics; the diffusion-collision model applied to proteins L and G

The diffusion-collision model (DCM) is applied to the folding kinetics of protein L and protein G. In the DCM, the two proteins are treated as consisting of two beta-hairpins and one alpha-helix, so that they are isomorphous with the three-helix bundle DCM model. In the absence of sequence dependent factors, both proteins would fold in the same way in the DCM, with the coalescence of the N-terminal hairpin and the helix slightly favored over the C-terminal hairpin and the helix because the former are closer together than the latter. However, sequence dependent factors make the N-terminal hairpin of protein L and the C-terminal hairpin of protein G more stable in the ensemble of unfolded conformations. This difference in the stabilities gives rise to the difference in the calculated folding behavior, in agreement with experiment.