Antimicrobial Activity of Actinobacteria Isolated From the Guts of Subterranean Termites.

Subterranean termites need to minimize potentially pathogenic and competitive fungi in their environment in order to maintain colony health. We examined the ability of Actinobacteria isolated from termite guts in suppressing microorganisms commonly encountered in a subterranean environment. Guts from two subterranean termite species, Reticulitermes flavipes (Kollar) and Reticulitermes tibialis Banks, were extracted and plated on selective chitin media. A total of 38 Actinobacteria isolates were selected for in vitro growth inhibition assays. Target microbes included three strains of Serratia marcescens Bizio, two mold fungi (Trichoderma sp. and Metarhizium sp.), a yeast fungus (Candida albicans (C.P. Robin) Berkhout), and four basidiomycete fungi (Gloeophyllum trabeum (Persoon) Murrill, Tyromyces palustris (Berkeley & M.A. Curtis) Murrill, Irpex lacteus (Fries) Fries, and Trametes versicolor (L.) Lloyd). Results showed both broad and narrow ranges of antimicrobial activity against the mold fungi, yeast fungus, and S. marcescens isolates by the Actinobacteria selected. This suggests that termite gut-associated Actinobacteria produce secondary antimicrobial compounds that may be important for pathogen inhibition in termites. Basidiomycete fungi were strongly inhibited by the selected Actinobacteria isolates, with G. trabeum and T. versicolor being most inhibited, followed by I. lacteus and T. palustris The degree of inhibition was correlated with shifts in pH caused by the Actinobacteria. Nearly all Actinobacteria isolates raised pH of the growth medium to basic levels (i.e. pH ∼8.0-9.5). We summarize antimicrobial activity of these termite gut-associated Actinobacteria and examine the implications of these pH shifts.

Expression of eosinophil-granule major basic protein messenger ribonucleic acid in placental X cells.

BACKGROUND: The human eosinophil-granule major basic protein (MBP) is a 13.8-kilodalton cationic polypeptide constituting the core of the eosinophil granule. MBP is cytotoxic to parasites and numerous mammalian cells and is a potent secretagogue for platelets, basophils, mast cells, and neutrophils. Concentrations of a molecule immunochemically similar to eosinophil granule MBP are present in maternal plasma, and MBP has been localized by immunofluorescence to placental X cells. EXPERIMENTAL DESIGN: To determine whether X cells produce MBP, the expression of MBP messenger RNA (mRNA) was investigated in placentas by Northern blot analyses and by in situ hybridization with 35S-labeled RNA probes. RESULTS: Northern blot analyses of RNA from placental septa and villi showed the existence of a 1.0-kb RNA band that hybridized with the MBP anti-sense probe; no MBP mRNA was detected in whole blood of normal or pregnant women or in cord blood. Analyses of placentas by in situ hybridization showed MBP mRNA in X cells of placental septa and anchoring villi, but not in other cellular elements such as syncytiotrophoblasts, cytotrophoblasts, villous stromal cells, and fetal endothelial cells. RNase pretreatment abolished X-cell hybridization signals; treatment of sections with an excess of nonradiolabeled anti-sense RNA also blocked binding of the 35S-labeled anti-sense RNA probe. Additional evidence supporting the production of MBP by X cells was obtained using a combination of in situ hybridization and immunofluorescence, which showed colocalization of MBP and its mRNA. CONCLUSIONS: The presence of MBP mRNA and MBP protein in placental X cells indicates that X cells synthesize this biologically active molecule.

Asthma in childhood. A review.

Asthma is currently considered by many to be a disease out of control. The prevalence and severity of asthma have increased in recent years, especially in children. Asthma is a very diagnosable condition. Better methods for treatment and monitoring now exist. It is hoped that with the implementation of expanded knowledge of asthma, this very common condition in childhood can be brought under better control.