Genetic control of the immune response to ferredoxin: linkage and mapping of T cell proliferation and antibody production genes to the MHC of mice

The genetics of the immune response in the mouse were studied by using the antigenically simple, stable, naturally occurring protein ferredoxin (Fd) from Clostridium pasteurianum. The immune status of mice primed and boosted with Fd was assessed by using two parameters of immunity: T cell proliferation and serum antibody production with the ELISA method. In both assay systems, the response has been shown to be H-2 linked: k, b, and s haplotypes respond to Fd, and H-2d mice are nonresponders. It is apparent that different immunoregulatory events modulate the response in the responder strains; these factors become evident in the recombinant analysis of the response and to date an immunoregulatory gene(s) has been mapped to at least the K/I-A subregions. F1 analysis demonstrated a gene dose-dependent response of the strains studied.     

A Metalloprotease Secreted by the Type II Secretion System Links Vibrio cholerae with Collagen

Vibrio cholerae is autochthonous to various aquatic niches and is the etiological agent of the life-threatening diarrheal disease cholera. The persistence of V. cholerae in natural habitats is a crucial factor in the epidemiology of cholera. In contrast to the well-studied V. cholerae-chitin connection, scarce information is available about the factors employed by the bacteria for the interaction with collagens. Collagens might serve as biologically relevant substrates, because they are the most abundant protein constituents of metazoan tissues and V. cholerae has been identified in association with invertebrate and vertebrate marine animals, as well as in a benthic zone of the ocean where organic matter, including collagens, accumulates. Here, we describe the characterization of the V. cholerae putative collagenase, VchC, encoded by open reading frame VC1650 and belonging to the subfamily M9A peptidases. Our studies demonstrate that VchC is an extracellular collagenase degrading native type I collagen of fish and mammalian origin. Alteration of the predicted catalytic residues coordinating zinc ions completely abolished the protein enzymatic activity but did not affect the translocation of the protease by the type II secretion pathway into the extracellular milieu. We also show that the protease undergoes a maturation process with the aid of a secreted factor(s). Finally, we propose that V. cholerae is a collagenovorous bacterium, as it is able to utilize collagen as a sole nutrient source. This study initiates new lines of investigations aiming to uncover the structural and functional components of the V. cholerae collagen utilization program.     

Antimicrobial activity of lavender,tea tree and lemon oils in cosmetic preservative systems

Aims: The aim of the study was to verify the antimicrobial activity of commercial essential oils: lavender, tea tree and lemon as the components of a preservative system in oil in water body milks. Methods and Results: The inhibition efficacy of essential oils alone (0·5%), in mixtures (1%) as well as combined with the synthetic preservative 1,3‐dimethylol‐5,5‐dimethylhydantoin and a 3‐iodo‐2‐propynyl butyl carbamate mixture (0·1% and 0·2%) was tested against Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 9027, Candida sp. ?OCK 0008 and Aspergillus niger ATCC 16404 in compliance with the standards of the European Pharmacopoeia Commission. The in vitro activity of oils determined by an impedimetric method was also compared with their activity in cosmetic preparations. Criterion A for bacteria (reduction in the inoculum by 3 logarithmic units within 7 days with no increase up to the 28th day) and fungi (reduction in the inoculum by 2 logarithmic units within 14 days with no increase up to the 28th day) was fulfilled for cosmetic formulations containing the tested essential oils with 0·2% of the synthetic preservative. The preservative concentration could be decreased to 0·1% (with preserving the same efficacy) in combination with lavender and tea tree oils at a concentration of 0·5% each. Conclusions: In all combinations of essential oils with the synthetic preservative, a synergistic effect of the preservative system components was observed, which made it possible to reduce the usable level of the synthetic preservative up to 8·5 times. Significance and Impact of the Study: To develop an effective preservative system in cosmetics in which a synthetic chemical preservative is replaced by natural essential oils.     

Biological control of Radopholus similis in banana by combined application of the mutualistic endophyte Fusarium oxysporum strain 162, the egg pathogen Paecilomyces lilacinus strain 251 and the antagonistic bacteria Bacillus firmus

The biological control efficacy of single or multiple applications of the mutualistic endophyte Fusarium oxysporum strain 162, the egg pathogen Paecilomyces lilacinus strain 251 and the antagonistic bacteria Bacillus firmus toward Radopholus similis was investigated in pot trials with banana under glasshouse conditions. R. similis was controlled substantially in single and combined applications of F. oxysporum with P. lilacinus or B. firmus. The combination of F. oxysporum and P. lilacinus caused a 68.5% reduction in nematode density whereas the individual applications reduced the density by 27.8% and 54.8% over the controls, respectively. Combined application of F. oxysporum and B. firmus was the most effective treatment in controlling R. similis on banana (86.2%), followed by B. firmus alone (63.7%). The compatibility of the biocontrol agents, as well the capacity of F. oxysporum to colonize banana roots in the absence or presence of P. lilacinus was also investigated. P. lilacinus did not adversely affect endophytic colonization by F. oxysporum. Biological control of R. similis in banana can therefore be enhanced via combined applications of antagonists with different modes of action that target different stages in the infection process. Handling editor: Ralf-Udo Ehlers     

Mathematical inference of the underground clonal growth of Epipactis helleborine (L.) Crantz (Orchidaceae, Neottieae)

Epipactis helleborine (L.) Crantz (Orchidaceae, Neottieae) can spread by sexual or vegetative propagation. The choice of strategy likely depends on the environmental conditions. The rhizome is the organ of vegetative reproduction; hence, it is crucial to understand its development. Unfortunately, it is hardly possible to investigate rhizome morphology directly, since E. helleborine is a protected species in most European countries. The goal of our investigation was to infer the growth patterns of underground parts of an orchid population from long-term annual observations of its aboveground shoots. We implemented the Minimum Spanning Tree method to determine a likely set of underground connections between shoots and to simulate the annual growth of new rhizomes. Furthermore, we modelled the spatial distribution of shoots with a density kernel estimator to compare the density gradients with the direction of growth of the rhizomes. Observed shoot numbers fluctuated between 72 and 183 from year to year. Our results suggest that (1) vegetative reproduction prevails in the studied population, (2) the population consists of about a dozen clones with a diameter of up to 6 m, (3) rhizomes produce up to five new shoots at one branch end per year, (4) rhizomes develop in the direction of decreasing population density, and (5) nodes of rhizomes may produce new offshoots after up to 7 years of dormancy.     

Early loss of proliferative potential of human peritoneal mesothelial cells in culture: the role of p16INK4a-mediated premature senescence.

Much has been learned about the mechanisms underlying cellular senescence. The pathways leading to senescence appear to vary, depending on the cell type and cell culture conditions. In this respect, little is known about senescence of human peritoneal mesothelial cells (HPMC). Previous studies have significantly differed in the reported proliferative lifespan of HPMC. Therefore, in the present study, we have examined how HPMC enter state of senescence under conditions typically used for HPMC culture. HPMC were isolated from omentum and grown into senescence. The cultures were assessed for the growth rate, the presence of senescence markers, activation of cell-cycle inhibitors, and the oxidative stress. HPMC were found to reach, on average, six population doublings before senescence. The terminal growth arrest was associated with decreased expression of Ki67 antigen, increased percentage of cells in the G1 phase, reduced early population doubling level cDNA-1 mRNA expression, and the presence of senescence-associated beta-galactosidase. Compared with early-passage cells, the late-passage HPMC exhibited increased expression of p16INK4a but not of p21Cip1. In addition, these cells generated more reactive oxygen species and displayed increased presence of oxidatively modified DNA (8-hydroxy-2'-deoxyguanosine). These results demonstrate that early onset of senescence in omentum-derived HPMC may be associated with oxidative stress-induced upregulation of p16INK4a.     

Interactions of Paecilomyces lilacinus strain 251 with the mycorrhizal fungus Glomus intraradices: Implications for Meloidogyne incognita control on tomato

The interactions of Paecilomyces lilacinus strain 251 with the arbuscular mycorrhizal fungus Glomus intraradices and their significance for the control of Meloidogyne incognita on tomato were investigated in greenhouse experiments. Application of P. lilacinus had no effect on the frequency and intensity of tomato root colonization by G. intraradices. Likewise, the decline of the nematophagous fungus densities after single application in soil was not affected by the presence of the mycorrhizal fungus. Single application of P. lilacinus, as pre-planting soil treatment, resulted in significant reduction of nematode damage. In contrast, mycorrhizal inoculation did not provide sufficient biocontrol. Combined application of the two agents did not enhance root protection compared to single treatments. Double treatment of mycorrhized seedlings with P. lilacinus, as seedling drench and pre-planting soil treatment, 4 and 1 week before transplanting, respectively, resulted in the highest reduction of the nematode damage. These results indicate the potential of the commercial P. lilacinus strain 251 and mycorrhiza for integration in nematode control strategies.