Molecular characterization of Pisolithus spp. isolates by rDNA PCR-RFLP

 Variation within ribosomal DNA (rDNA) genes of 19 isolates of Pisolithus from different geographic origins and hosts was examined by polymerase chain reaction (PCR) coupled with restriction fragment length polymorphism (RFLP) analysis. The primers utilized amplify rDNA regions in a wide range of fungi. One amplified region includes the internal transcribed spacer (ITS), which has a low degree of conservation. The ITS amplification products (640–750 bp) were digested with a variety of restriction endonucleases. Cluster analysis based on the restriction fragments grouped the isolates into three distinct groups: group I contained isolates collected in the northern hemisphere, except Pt 1, group II contained those collected in Brazil and group III contained isolate Pt 1. Additional analysis of other rDNA regions, IGS, 17 S and 25 S rDNA, resulted in similar groups. The data suggest that the taxonomy and systematics of this ectomycorrhizal fungus should be revised. Accepted: 16 September 1998     

Calcium oscillations encoding neuron-to-astrocyte communication.

The observation that the excitatory neurotransmitter glutamate released from presynaptic terminals can activate, beside the post-synaptic neuron, the glial cell astrocyte, stimulated glial cell research like no other event since the recognition in the 1980s that astrocytes can express on their membrane many receptors for classical neurotransmitters. The properties and the functional role(s) of such a neuron-to-astrocyte signaling have now become the focus of intense research in neurobiology. Indeed, a growing body of evidence has recently highlighted the ability of astrocytes to work as sophisticated detectors of synaptic activity: by changing the frequency of [Ca(2+)](i) oscillations evoked by the synaptic release of glutamate, these cells display the remarkable capacity to discriminate between different levels and patterns of synaptic activity. Furthermore, the observation that astrocytes increase the frequency of [Ca(2+)](i) oscillations in response to repetitive episodes of high neuronal activity challenges the common concept that memory function in the brain is an exclusive property of neuronal cells. Glutamate-mediated [Ca(2+)](i) elevations can also trigger in astrocytes the release of glutamate that can ultimately affect neuronal transmission. Given the wide role played by glutamate in brain physiology, our view on how the brain operates needs now to be revised taking into account the bi-directional, glutamatergic communication between neurons and astrocytes.     

Fermentation of maltose and starch by Klebsiella oxytoca P2

Klebsiella oxytoca P2, which has genes from Zymomonas mobilis encoding the alcohol dehydrogenase and pyruvate decarboxylase integrated in its chromosome, fermented 50 g maltose/l to 25.4 g of ethanol/l. It also fermented 10, 20 and 40 g starch/l yielding 4, 8.4, and 17.7 g ethanol/l, respectively, representing 72, 75 and 78% of the theoretical yield. © Rapid Science Ltd. 1998     

A proteomic approach to identifying proteins differentially expressed in conidia and mycelium of the entomopathogenic fungus Metarhizium acridum

Metarhizium spp. is an important worldwide group of entomopathogenic fungi used as an interesting alternative to chemical insecticides in programs of agricultural pest and disease vector control. Metarhizium conidia are important in fungal propagation and also are responsible for host infection. Despite their importance, several aspects of conidial biology, including their proteome, are still unknown. We have established conidial and mycelial proteome reference maps for Metarhizium acridum using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF MS). In all, 1130±102 and 1200±97 protein spots were detected in ungerminated conidia and fast-growing mycelia, respectively. Comparison of the two protein-expression profiles reveled that only 35% of the protein spots were common to both developmental stages. Out of 94 2-DE protein spots (65 from conidia, 25 from mycelia and two common to both) analyzed using mass spectrometry, seven proteins from conidia, 15 from mycelia and one common to both stages were identified. The identified protein spots exclusive to conidia contained sequences similar to known fungal stress-protector proteins (such as heat shock proteins (HSP) and 6-phosphogluconate dehydrogenase) plus the fungal allergen Alt a 7, actin and the enzyme cobalamin-independent methionine synthase. The identified protein spots exclusive to mycelia included proteins involved in several cell housekeeping biological processes. Three proteins (HSP 90, 6-phosphogluconate dehydrogenase and allergen Alt a 7) were present in spots in conidial and mycelial gels, but they differed in their locations on the two gels.     

In vitro and in vivo studies of boron neutron capture therapy: boron uptake/washout and cell death

Boron neutron capture therapy (BNCT) is a binary radiotherapy based on thermal-neutron irradiation of cells enriched with (10)B, which produces α particles and (7)Li ions of short range and high biological effectiveness. The selective uptake of boron by tumor cells is a crucial issue for BNCT, and studies of boron uptake and washout associated with cell survival studies can be of great help in developing clinical applications. In this work, boron uptake and washout were characterized both in vitro for the DHDK12TRb (DHD) rat colon carcinoma cell line and in vivo using rats bearing liver metastases from DHD cells. Despite a remarkable uptake, a large boron release was observed after removal of the boron-enriched medium from in vitro cell cultures. However, analysis of boron washout after rat liver perfusion in vivo did not show a significant boron release, suggesting that organ perfusion does not limit the therapeutic effectiveness of the treatment. The survival of boron-loaded cells exposed to thermal neutrons was also assessed; the results indicated that the removal of extracellular boron does not limit treatment effectiveness if adequate amounts of boron are delivered and if the cells are kept at low temperature. Cell survival was also investigated theoretically using a mechanistic model/Monte Carlo code originally developed for radiation-induced chromosome aberrations and extended here to cell death; good agreement between simulation outcomes and experimental data was obtained.