In vitro susceptibility ofPityrosporum ovale (Malassezia furfur) to human androgenic steroids

Cells ofPityrosporum ovale that colonize human pilosebaceous units are constantly exposed to cutaneous androgenic steroids. The aim of our study was to find out whetherP. ovale is susceptible to these hormones. Three strains ofP. ovale were grown in vitro in the presence of various concentrations oftestosterone, dehydroepiandrosterone, androstenedione, androstanedione, 5--dihydrotestosterone andprogesterone (10, 100, and 1000 µg/ml; agar dilution assays). In addition, three strains ofCandida albicans were also exposed to equal concentrations of the same androgens. As a result, allP. ovale strains were suppressed by 1000 µg/mlandrostenedione, which was the strongest inhibitor. The other androgenic steroids also significantly reducedP. ovale growth at different concentrations, depending on the hormone used and the strain tested.Progesterone was inhibitory at the highest concentration for oneP. ovale strain only.Candida albicans was not affected by any of the androgens. These findings demonstrate an in vitro susceptibility ofP. ovale to high concentrations of human androgenic steroids. A relevance of this interaction for the in vivo fungus-host relation is not apparent.     

mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

Nuclear bodies (NBs): a newly "rediscovered" organelle.

Nuclear bodies (NBs) were first described in detail some 30 years ago, by conventional electron microscopy, as prominent interchromatin structures found primarily in the nuclei of malignant or hyperstimulated animal cells. Subsequent studies have shown that NBs are ubiquitous organelles, but they are numerically and morphologically quite varied. With the recent discovery of human autoantibodies against several key nuclear antigens present in some NBs, these structures are once again the subject of much attention. At least one class of NBs, coiled bodies, has been shown to be nucleolus-derived and to contain not only nucleolus-associated antigens, but also many of the snRNP components involved in pre-mRNA splicing. These data suggest that coiled bodies, and perhaps other NBs as well, are multifunctional and may be involved in the processing or transport of both pre-mRNA and pre-rRNA. Further evidence is provided showing that NBs constitute distinct nuclear domains whose functional significance is just now emerging.     

Nuclear bodies (NBs): A newly “rediscovered” organelle

Nuclear bodies (NBs) were first described in detail some 30 years ago, by conventional electron microscopy, as prominent interchromatin structures found primarily in the nuclei of malignant or hyperstimulated animal cells. Subsequent studies have shown that NBs are ubiquitous organelles, but they are numerically and morphologically quite varied. With the recent discovery of human autoantibodies against several key nuclear antigens present in some NBs, these structures are once again the subject of much attention. At least one class of NBs, coiled bodies, has been shown to be nucleolus-derived and to contain not only nucleolus-associated antigens, but also many of the snRNP components involved in pre-mRNA splicing. These data suggest that coiled bodies, and perhaps other NBs as well, are multifunctional and may be involved in the processing or transport of both pre-mRNA and pre-rRNA. Further evidence is provided showing that NBs constitute distinct nuclear domains whose functional significance is just now emerging.     

Patterns of exchange induced by mitomycin C in C-bands of human chromosomes. I. Relationship to C-band size in chromosomes 1, 9, and 16

Summary Frequencies of exchange were determined in C-bands of chromosomes 1, 9 and 16 in six normal males, and related to relative C-band area. Comparing these different chromosomes, more exchanges occurred on average in 9 than in 1 although their mean C-band sizes were similar. Chromosome 16 exchanges were fewer, both overall and relative to C-band area. Comparing the same chromosome between individuals, there was a positive correlation between relative frequency and band size in both 1-1 and 9-9 exchanges. No clear trend was observed for other exchange events.If homology is required for interchange, if cannot be dependent solely on overall C-band size. Perhaps certain DNA sequences, sensitive to mitomycin C damage, are located in part of each C-band, with less per unit area in chromosome 1 than in 9 and still less in chromosome 16.X- and U-type exchanges between chromosome 9s occurred in near equal frequencies in all individuals. If synapsis of specific, affected sequences is a pre-requisite for interchange, this observation suggests that the affected sequence in chromosome 9 is arranged in both orientations relative to the centromere.     

The galactan sulfate from the edible,red alga Porphyra columbina

A galactan sulfate has been isolated from the seaweed Porphyra columbina, and its structure established by a combination of methylation, methanolysis, treatment with alkali followed by methylation, and ¹³C-n.m.r. spectroscopy. The polysaccharide belongs to the porphyran class, and consists of 3-linked β-d-galactosyl residues and 4-linked α-l-galactosyl residues. 3,6-Anhydro-l-galactose and l-galactose 6-sulfate residues total approximately half of the sugar units, the other half being made up of d-galactose and 6-O-methyl-d-galactose residues. Some evidence is presented that suggests that the galactan sulfate does not have a completely alternating structure.     

Structural Transitions and Energy Landscape for Cowpea Chlorotic Mottle Virus Capsid Mechanics from Nanomanipulation in?Vitro and in Silico

Physical properties of capsids of plant and animal viruses are important factors in capsid self-assembly, survival of viruses in the extracellular environment, and their cell infectivity. Combined AFM experiments and computational modeling on subsecond timescales of the indentation nanomechanics of Cowpea Chlorotic Mottle Virus capsid show that the capsid’s physical properties are dynamic and local characteristics of the structure, which change with the depth of indentation and depend on the magnitude and geometry of mechanical input. Under large deformations, the Cowpea Chlorotic Mottle Virus capsid transitions to the collapsed state without substantial local structural alterations. The enthalpy change in this deformation state ΔH_ind = 11.5–12.8 MJ/mol is mostly due to large-amplitude out-of-plane excitations, which contribute to the capsid bending; the entropy change TΔS_ind = 5.1–5.8 MJ/mol is due to coherent in-plane rearrangements of protein chains, which mediate the capsid stiffening. Direct coupling of these modes defines the extent of (ir)reversibility of capsid indentation dynamics correlated with its (in)elastic mechanical response to the compressive force. This emerging picture illuminates how unique physico-chemical properties of protein nanoshells help define their structure and morphology, and determine their viruses’ biological function.     

Structural Transitions and Energy Landscape for Cowpea Chlorotic Mottle Virus Capsid Mechanics from Nanomanipulation in Vitro and in Silico

Physical properties of capsids of plant and animal viruses are important factors in capsid self-assembly, survival of viruses in the extracellular environment, and their cell infectivity. Combined AFM experiments and computational modeling on subsecond timescales of the indentation nanomechanics of Cowpea Chlorotic Mottle Virus capsid show that the capsid’s physical properties are dynamic and local characteristics of the structure, which change with the depth of indentation and depend on the magnitude and geometry of mechanical input. Under large deformations, the Cowpea Chlorotic Mottle Virus capsid transitions to the collapsed state without substantial local structural alterations. The enthalpy change in this deformation state ΔH_ind = 11.5–12.8 MJ/mol is mostly due to large-amplitude out-of-plane excitations, which contribute to the capsid bending; the entropy change TΔS_ind = 5.1–5.8 MJ/mol is due to coherent in-plane rearrangements of protein chains, which mediate the capsid stiffening. Direct coupling of these modes defines the extent of (ir)reversibility of capsid indentation dynamics correlated with its (in)elastic mechanical response to the compressive force. This emerging picture illuminates how unique physico-chemical properties of protein nanoshells help define their structure and morphology, and determine their viruses’ biological function.     

Oligosaccharides related to xyloglucan: synthesis and X-ray crystal structure of methyl alpha-L-fucopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-alpha-D-x ylopyranoside and the synthesis of methyl alpha-L-fucopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-beta-D-xy lopyranoside

Trisaccharides, methyl alpha-L-fucopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-alpha-D-xy lopyranoside and methyl alpha-L-fucopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-beta-D-xyl opyranoside, which are related to the side chain of xyloglucan have been synthesised. The beta-galactopyranosyl linkage of each was constructed using silver trifluoromethanesulfonate-promoted glycosylations of 2-O-acetyl-3,4,6-tri-O-benzyl-beta-D-galactopyranosyl chloride and the corresponding anomer of methyl 3,4-tri-O-benzyl-D-xylopyranoside. The resulting disaccharides were deacetylated and fucosylated using assisted halide reactions with tri-O-benzyl-alpha-L-fucopyranosyl bromide. Hydrogenolytic debenzylation of the resulting protected trisaccharides gave the methyl glycosides of the fucose-containing xyloglucan side chain. The structure of methyl alpha-L-fucopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->2)-alpha-D-xy lopyranoside as the monohydrate was confirmed by an X-ray crystallographic study.