bluuebunny/crossref_metadata_2025 huggingface dataset:
What’s not wrong with conditional organ donation?
Authors: Wilkinson T M
Published: June 2003

In a well known British case, the relatives of a dead man consented to the use of his organs for transplant on the condition that they were transplanted only into white people. The British government condemned the acceptance of racist offers and the panel they set up to report on the case condemned all conditional offers of donation. The panel appealed to a principle of altruism and meeting the greatest need. This paper criticises their reasoning. The panel’s argument does not show that conditional donation is always wrong and anyway overlooks a crucial distinction between making an offer and accepting it. But even the most charitable reinterpretation of the panel’s argument does not reject selective acceptance of conditional offers. The panel’s reasoning has no merit.
Brain donation for schizophrenia research: gift, consent, and meaning
Authors: Boyes M , Ward P
Published: June 2003

The Neuroscience Institute of Schizophrenia and Allied Disorders’s (NISAD) “Gift of Hope” Tissue Donor Program is a volunteer programme for people who wish to donate their brain when they die for neuroscience research into schizophrenia. Organ donation for purposes of research differs from transplant donation in a number of ways, most notably the absence of a single recipient. Within a particular community, however, (people with schizophrenia and their carers) the single recipient is replaced by a sense of shared experience and preventing suffering in others. Donors have an investment in the research.
Human organs from prisoners: kidneys for life
Authors: de Castro L D
Published: June 2003

A proposal to allow prisoners to save their lives or to be eligible for commutation of sentence by donating kidneys for transplantation has been a subject of controversy in the Philippines. Notwithstanding the vulnerabilities associated with imprisonment, there are good reasons for allowing organ donations by prisoners. Under certain conditions, such donations can be very beneficial not only to the recipients but to the prisoners themselves. While protection needs to be given to avoid coercion and exploitation, overprotection has to be avoided. The prohibition on the involvement of prisoners in organ transplantation constitutes unjustified overprotection. Under certain conditions, prisoners can make genuinely independent decisions. When it can be reasonably ascertained that they are able to decide freely, society should recognise an obligation to help them implement their decisions, such as when they intend to donate an organ as a way of asserting their religious faith and performing a sacrifice in atonement for their sins.
Non-heart beating organ donation: old procurement strategy—new ethical problems
Authors: Bell M D D
Published: June 2003

The imbalance between supply of organs for transplantation and demand for them is widening. Although the current international drive to re-establish procurement via non-heart beating organ donation/donor (NHBOD) is founded therefore on necessity, the process may constitute a desirable outcome for patient and family when progression to brain stem death (BSD) does not occur and conventional organ retrieval from the beating heart donor is thereby prevented. The literature accounts of this practice, however, raise concerns that risk jeopardising professional and public confidence in the broader transplant programme. This article focuses on these clinical, ethical, and legal issues in the context of other approaches aimed at increasing donor numbers. The feasibility of introducing such an initiative will hinge on the ability to reassure patients, families, attendant staff, professional bodies, the wider public, law enforcement agencies, and the media that practitioners are working within explicit guidelines which are both ethically and legally defensible.
The altruistic act of asking
Authors: Kirklin D
Published: June 2003

There are a number of obstacles to increasing the supply of cadaveric organs for transplantation. These include reluctance on the part of relatives to agree to the so called harvesting of organs from their deceased relative, and the unwillingness of some doctors to approach grieving families and ask consent for this harvesting to take place. In this paper I will focus on the altruistic act of asking that the latter entails, and will argue that failure to acknowledge the personal cost of this act to physicians is having an adverse impact on the supply of organs. I will draw analogies with the almost equally neglected altruistic act of undertaking anatomy dissection and all of the related breaking of societal taboos. I will examine the language used in discussions about increasing organ supply and conclude that the terms cadaveric and harvest are unhelpful in gaining public confidence. A process and vocabulary that openly acknowledges and validates the altruistic acts demanded of all the human beings involved—donors, recipients, their respective relatives, and the health professionals who mediate between them—is needed if the supply of organs is to be increased.
Early interactions ofEntamoeba histolyticatrophozoites with parenchymal and inflammatory cells in the hamster liver: an immunocytochemical study
Authors: Ventura-Juárez J , Campos-Rodríguez R , Tsutsumi V
Published: June 2003

We studied the early in situ interactions of live and fixed Entamoeba histolytica trophozoites with hamster hepatic parenchymal and inflammatory cells using immunoperoxidase and immunoelectronmicroscopy. Close contact between trophozoites and endothelial cells and the diffusion of amoebic molecules from trophozoites towards nearby endothelial cells and distant hepatocytes were observed. The inflammatory cells around the amoebae and the remnants of parenchymal cells and hepatocytes located close to the lesion had a positive stain for amoebic molecules. In the amoebae, at the ultrastructural level, molecules were attached to the membranes and inside the vesicles. These molecules were apparently released into the space formed between the parasite and the endothelial cells. The endothelial cells and the nearby and distant hepatocytes captured amoebic molecules, and later they became necrotic. Contrarily, when fixed amoebae were inoculated, amoebic molecules were captured by endothelial cells and polymorphonuclear (PMN) leukocytes, but neither suffered any damage. In this work, we are presenting evidence clearly showing that some molecules of the amoeba can diffuse away long distances causing cytotoxic effects and even necrosis on hepatic cells of hamster liver without the need of the trophozoite being in close contact with the target cells. They also may promote lytic or proinflammatory effects by inducing the secretion of enzymes or cytokines in other nonparenchymal cells, like PMN leukocytes and endothelial cells. Our results suggest that the accepted mechanisms of cytotoxicity by amoebae are not exclusively restricted to the following sequence: adhesion, phagocytosis, and necrosis.Key words: amoebiasis, Entamoeba histolytica, liver, hamster, immunocytochemistry.
Sequence analysis of pLBB1, a cryptic plasmid from Lactobacillus delbrueckii subsp. bulgaricus
Authors: Azcárate-Peril M Andrea , Raya Raúl R
Published: June 2003

The first report of the complete nucleotide sequence of a cryptic plasmid from Lactobacillus delbrueckii subsp. bulgaricus (Lactobacillus bulgaricus) is presented. The plasmid pLBB1 consists of 6127 bp with a GC content of 44.8%. No ssDNA was detected by hybridization experiments, which is consistent with the notion that pLBB1 does not replicate by a rolling circle mechanism. A putative replication region of pLBB1 was cloned and found to be functional in Lactobacillus johnsonii and Lactococcus lactis. Plasmid pLBB1 showed significant DNA sequence identity with plasmid pLL1212 from Lactobacillus delbrueckii subsp. lactis (Lactobacillus lactis) CRL1212 (GenBank accession No. AF109691). Four open reading frames (ORFs) larger than 100 amino acids were identified. ORFA shared similarity with a putative primasehelicase system, and ORFB and ORFC exhibited limited identity with a mobilization protein and a transposase, respectively. Curing experiments did not allowed us to assign a function to the ORFs.Key words: Lactobacillus, cryptic plasmid, sequence analysis.
Total microbial activity and microbial composition of a mangrove sediment are reduced by oil pollution at a site in the Arabian Gulf
Authors: El-Tarabily Khaled A
Published: June 2003

In a study carried out to determine the effect of oil pollution on the microbiota of sediment associated with mangroves in the United Arab Emirates, sediment samples were collected from oil-polluted and nonpolluted mangrove sites. The levels of the total recoverable hydrocarbons and the polycyclic aromatic hydrocarbons assayed were noticeably higher in the polluted sediment. Microbial activity as measured by the hydrolysis of fluorescein diacetate and by the total populations of the culturable aerobic and anaerobic bacteria, streptomycete and non-streptomycete actinomycetes, and filamentous fungi and yeasts was significantly (P < 0.05) lower in the polluted than in the nonpolluted sediment. The estimated total aerobic and anaerobic hydrocarbon-utilizing bacteria were significantly (P < 0.05) higher in the polluted than in the nonpolluted sediments. Four days after the addition of the water-soluble fractions of the light Arabian crude oil to the nonpolluted sediment, at 10 different concentrations, there was a significant (P < 0.05) reduction (65%) in the microbial activity of the sediment compared with that of nonamended sediment. Concentrations of water-soluble fractions at 0.1% and above significantly and progressively reduced microbial activity, with total cessation of activity recorded at levels >50%. This study is the first to evaluate the effect of oil pollution on aerobic and anaerobic microbial flora of sediment of mangrove communities.Key words: crude oil, fluorescein diacetate, anaerobic bacteria, polycyclic aromatic hydrocarbons, United Arab Emirates.
Increased ratio of mitochondrial rDNA to cytoplasmic rDNA during zoosporic and germinating cyst stages of the life cycle of Phytophthora infestans (Mont.) de Bary
Authors: París Ramiro , Lamattina Lorenzo
Published: June 2003

A differential RNA display approach was used to study the gene expression in zoospores (Z) and germinating cysts (GC) of the late blight pathogen Phytophthora infestans. Four differentially amplified cDNAs were selected and cloned. The clone pGPiZ0.5 showed a 2.7-kb transcript highly expressed in Z. A BLAST search revealed an almost full sequence homology (98%) to the P. infestans mitochondrial large subunit rRNA. Northern blot analysis showed a twofold accumulation of the mitochondrial rRNA (mit rRNA) in Z compared with that of GC and mycelia of P. infestans. The high level of mit rRNA in Z might reflect an increased number of gene copies, an increased rDNA transcription rate, or both. Dot blot experiments indicated that the amount of mitochondrial rDNA (mit rDNA) relative to cytoplasmic rDNA is twofold higher in Z and GC than in mycelia. This relatively elevated mit rDNA could explain the high level of mit rRNA in the zoosporic phase. On the contrary, GC conserves the mit rDNA content, but the level of mit rRNA drops to 50% that of Z. The data are consistent with a very active mitochondrial protein synthesis during zoosporic phase, followed by a rapid down-regulation of mitochondrial activity during cyst formation.Key words: cytoplasmic rRNA, differential RNA display, mitochondrial rRNA, Phytophthora infestans, rDNA.
Stimulatory effect of aerosil on algal growth
Authors: Gerashchenko Bogdan I , Gerashchenko Igor I , Kosaka Toshikazu , Hosoya Hiroshi
Published: June 2003

Unicellular green alga represents not only a convenient model for its biochemical and physiological studies but also a sensitive system to test the effects of various environmental factors. Algae cells of two strains, SA-3 strain (exsymbiotic from Paramecium bursaria) and Chlorella vulgaris c-27, were asynchronously cultured in the presence of 0.01% Aerosil A-300. Aerosil effects on algae were monitored at logarithmic and stationary phases of their growth by flow cytometry and microscopic counting of algal numbers. The growth patterns of algae were evaluated by their forward light scatter versus fluorescence of endogenous chlorophyll (FL3-height) signal distributions. Although aerosil itself did not cause any direct effects on algal morphology, it affected the growth patterns and the numbers of algae of both strains. Their growth patterns were remarkably altered in the late logarithmic phase cultures (6-day cultures). However, a significant increase of cell numbers was found in the stationary phase cultures (9- and 12-day cultures). While C. vulgaris c-27 demonstrated an increase of cell numbers by approximately 11% in the 9- and 12-day cultures, the amounts of SA-3 cells in the 9- and 12-days cultures were increased by 16% and 35%, respectively. Our study shows aerosil in its colloidal form stimulates proliferation of algae mainly via an acceleration of their life cycles. The stimulatory effect of silica on the growth of algae, the mechanism of which remains to be clarified, might have a practical (e.g., ecological) interest for regulation of algal expansion.Key words: aerosil, cloned algae, growth, forward light scatter, chlorophyll fluorescence.
Maturation of barley cysteine endopeptidase expressed inTrichoderma reeseiis distorted by incomplete processing
Authors: Nykänen Marko J , Raudaskoski Marjatta , Nevalainen Helena , Mikkonen Anita
Published: June 2003

Maturation of barley cysteine endopeptidase B (EPB) in Trichoderma reesei was studied with metabolic inhibitors, Western blotting, and immuno microscopy. The inactive 42-kDa recombinant EPB proprotein, first detected in apical cells, was sequentially processed in a time-dependent manner to a secreted polypeptide of 38.5 kDa, and thereafter, to polypeptides of 37.5, 35.5, and 32 kDa exhibiting enzyme activity both in the hyphae and culture medium. The sizes of the different forms of recombinant EPB were in accordance with molecular masses calculated from the deduced amino acid sequence, assuming cleavage at four putative Kex2p sites present in the 42-kDa proprotein. Both the liquid and the zymogram in-gel activity assays indicated that the 32-kDa enzyme produced in T. reesei in vivo was 2 kDa larger and four times less active than the endogenous EPB. Brefeldin A treatment prevented the last Kex2p processing step of EPB from a 35.5- to a 32-kDa protein. This coincided with a significant increase in the immuno-gold label for EPB and in modified Golgi-like bodies, which suggests that the processing step probably took place in medial Golgi. A 30.5-kDa EPB polypeptide was observed when glycosylation was inhibited by tunicamycin (TM) or when deglycosylation was carried out enzymatically. Deglycosylation increased the enzyme activity twofold, which was also indicated by an increased fluorescence by TM treatment in the zymogram in-gel activity assay. Simultaneous incubation with TM and monensin produced a peptide of 31.5 kDa. Therefore, monensin may inhibit the final processing step of an unglycosylated EPB by an unknown protease in the fungus. In any case, the final recombinant EPB product in Trichoderma differs from the mature endogenous 30-kDa enzyme produced in barley.Key words: cysteine proteinase, secretion, Kex2p, glycosylation, modified Golgi-like body.
Isolation of an Escherichia coli strain mutant unable to form biofilm on polystyrene and to adhere to human pneumocyte cells: involvement of tryptophanase
Authors: Di Martino P , Merieau A , Phillips R , Orange N , Hulen C
Published: June 2003

Escherichia coli adherence to biotic and abiotic surfaces constitutes the first step of infection by promoting colonization and biofilm formation. The aim of this study was to gain a better understanding of the relationship between E. coli adherence to different biotic surfaces and biofilm formation on abiotic surfaces. We isolated mutants defective in A549 pneumocyte cells adherence, fibronectin adherence, and biofilm formation by random transposition mutagenesis and sequential passages over A549 cell monolayers. Among the 97 mutants tested, 80 were decreased in biofilm formation, 8 were decreased in A549 cells adherence, 7 were decreased in their adherence to fibronectin, and 17 had no perturbations in either of the three phenotypes. We observed a correlation between adherence to fibronectin or A549 cells and biofilm formation, indicating that biotic adhesive factors are involved in biofilm formation by E. coli. Molecular analysis of the mutants revealed that a transposon insertion in the tnaA gene encoding for tryptophanase was associated with a decrease in both A549 cells adherence and biofilm formation by E. coli. The complementation of the tnaA mutant with plasmid-located wild-type tnaA restored the tryptophanase activity, epithelial cells adherence, and biofilm formation on polystyrene. The possible mechanism of tryptophanase involvement in E. coli adherence and biofilm formation is discussed.Key words: Escherichia coli, biofilm, adherence, A549 cells, fibronectin, tryptophanase.
Paenibacillus polymyxaproduces fusaricidin-type antifungal antibiotics active againstLeptosphaeria maculans, the causative agent of blackleg disease of canola
Authors: Beatty Perrin H , Jensen Susan E
Published: June 2003

A bacterial isolate capable of inhibiting the growth of Leptosphaeria maculans (Desmaz.) Ces. & De Not., the causative agent of blackleg disease of canola (Brassica napus L. and Brassica rapa L.), was identified as a potential biological control agent. This environmental isolate was determined to be Paenibacillus polymyxa based on its (i) biochemical and growth characteristics and (ii) 16S rRNA sequence similarity, and was given the strain designation PKB1. Antifungal peptides were produced by P. polymyxa PKB1 around the onset of sporulation, with optimal production on potato dextrose broth. The antifungal peptides were extracted from P. polymyxa PKB1 cells and (or) spores using methanol and were purified using size exclusion and reverse-phase chromatography. Characterization of the antifungal peptides was done using amino acid compositional analysis, Edman degradation sequencing from partially hydrolyzed material, and a variety of mass spectrometric methods. The purified antifungal material was found to be a mixture of related peptides of molecular masses 883, 897, 948, and 961 Da, with the most likely structure of the 897-Da component determined to be a cyclic depsipeptide with an unusual 15-guanidino-3-hydroxypentadecanoic acid moiety bound to a free amino group. These compounds are therefore members of the fusaricidin group of cyclic depsipeptides.Key words: cyclic depsipeptide, biocontrol agent, allo-threonine.
Hydrolytic enzymes and antifungal compounds produced byTilletiopsisspecies, phyllosphere yeasts that are antagonists of powdery mildew fungi
Authors: Urquhart E J , Punja Z K
Published: June 2003

Isolates of five species of the yeast-like fungus Tilletiopsis Derx (Tilletiopsis albescens Gokhale, Tilletiopsis fulvescens Gokhale, Tilletiopsis minor Nyland, Tilletiopsis pallescens Gokhale, and Tilletiopsis washingtonensis Nyland) were screened for exo- and endo-β-1,3-glucanase and chitinase production in a liquid broth used to produce inoculum for biological control studies. There were significant differences among the species, and highest overall enzyme activity was present in T. albescens and T. pallescens and lowest in T. washingtonensis. A time-course study of β-1,3-glucanase and chitinase production in T. pallescens ATCC 96155 in broth culture with 2.5% glucose as the carbon source showed that enzyme activity gradually increased over a 3- to 21-day period. Maximum enzyme activity was found between pH 4.0 and 5.0. SDS-PAGE of β-1,3-glucanase isozymes revealed a range of molecular masses from 18 to 29 kDa. Five isozymes were present in both T. albescens and T. pallescens and two in T. washingtonensis. Antifungal compounds were also detected in ethyl acetate extracts of culture filtrates of T. pallescens ATCC 96155 after 6 days of incubation, while no activity was detected at 14 days. One active fraction was selected following fractionation and preparative chromatography and was bioassayed against Podosphaera (sect. Sphaerotheca) xanthii (Castagne) U. Braun & N. Shishkoff and a number of other fungi. A concentration of 130 µg/mL inhibited germ tube development in P. xanthii, and mildew spores appeared plasmolyzed. Other fungi were inhibited at higher concentrations. Collapse of hyphae and conidiophores was also observed on mildewed leaves treated with the active fraction. Proton NMR analysis indicated that the inhibitory compound was a fatty acid ester. In 3- to 6-day-old cultures of T. pallescens ATCC 96155 demonstrating biological control activity, antifungal compound production may have a primary role in restricting growth of mildew fungi and other competitors when applied to leaves.Key words: biological control, antibiotics, chitinases, glucanases, powdery mildew.
The relative ability of fungi fromSphagnum fuscumto decompose selected carbon substrates
Authors: Thormann Markus N , Currah Randolph S , Bayley Suzanne E
Published: June 2003

Nine species from a suite of 55 microfungi isolated from living and decomposing Sphagnum fuscum were selected for studies of in vitro decomposition of tannic acid, cellulose, and starch. In vitro decomposition of S. fuscum plants and spruce wood chips was also examined. Oidiodendron maius and Oidiodendron scytaloides degraded tannic acid, giving a positive reaction for polyphenol oxidases. Most taxa degraded cellulose and starch via the synthesis of cellulases and amylase, respectively. Mass losses of spruce wood chips generally exceeded those of S. fuscum. A basidiomycete, similar to Bjerkandera adusta, caused the greatest mass losses in spruce wood chips (10.2%), while O. scytaloides caused the smallest mass losses (3.4%) after 8 weeks. For S. fuscum, Sordaria fimicola caused the greatest (5.1%) and Mucor hiemalis the smallest (0.1%) mass losses after 8 weeks. Filamentous microfungi have considerable potential to decompose a variety of carbon substrates of bryophilous residues in peatlands.Key words: microfungi, Sphagnum fuscum, peatlands, carbon, decomposition.
Purification and characterization of a glucoamylase secreted by the plant pathogenSclerotinia sclerotiorum
Authors: Martel M B , Penhoat C Hervé du , Létoublon R , Fèvre M
Published: June 2003

Among the lytic enzymes secreted by the phytopathogen fungus Sclerotinia sclerotiorum, a starch-degrading enzyme has been isolated and characterized. This glycoprotein of 72 kDa is composed of several isoforms ranging from pI 4.8 to 5.4. The enzymatic parameters have been determined. Specificity studies together with the analysis of the reaction products show that it is an α-1,4-glucanohydrolase. This result is also corroborated by the analysis of the N-terminal and two inner amino acids sequences that are very similar to fungal glucoamylase genes or enzymes so far sequenced.Key words: hydrolase, glucoamylase, Sclerotinia sclerotiorum, starch-degrading enzyme.
Effect of different carbon sources and cold shock on protein synthesis by a psychrotrophicAcinetobactersp.
Authors: Barbaro S E , Trevors J T , Inniss W E
Published: June 2003

The induction of proteins after a 25 to 5°C cold shock in the psychrotrophic Acinetobacter HH1-1 was examined using two-dimensional polyacrylamide gel electrophoresis. In addition, effects of various carbon sources (acetate, Tween 80, and olive oil) on protein synthesis after cold shock were assessed. HH1-1 responded to cold shock by synthesizing both cold shock proteins (csps) and cold acclimation proteins (caps). The synthesis of two csps (89 and 18) was increased 2 h after cold shock by the cells, regardless of the carbon source provided. An additional csp (csp 12), with an estimated molecular mass of 12 kDa, was observed in cells grown in olive oil only. Csp 12 was also synthesized when cells were incubated at 30°C, suggesting that this protein may serve as a general stress protein. In addition to csps, caps were observed post cold shock at 72 h in acetate-grown cells and at 140 h in cells grown in Tween 80 and olive oil. Induction of cold-acclimated periplasmic proteins was observed for cells grown in olive oil only, suggesting cells grown in olive oil may be stressed by low temperatures to a greater extent than cells grown in either acetate or Tween 80.Key words: Acinetobacter, carbon sources, cold shock, protein synthesis, temperature.
Isolation of plant-growth-promotingBacillusstrains from soybean root nodules
Authors: Bai Yuming , D'Aoust Frederic , Smith Donald L , Driscoll Brian T
Published: June 2003

Endophytic bacteria reside within plant tissues and have often been found to promote plant growth. Fourteen strains of putative endophytic bacteria, not including endosymbiotic Bradyrhizobium strains, were isolated from surface-sterilized soybean (Glycine max. (L.) Merr.) root nodules. These isolates were designated as non-Bradyrhizobium endophytic bacteria (NEB). Three isolates (NEB4, NEB5, and NEB17) were found to increase soybean weight when plants were co-inoculated with one of the isolates and Bradyrhizobium japonicum under nitrogen-free conditions, compared with plants inoculated with B. japonicum alone. In the absence of B. japonicum, these isolates neither nodulated soybean, nor did they affect soybean growth. All three isolates were Gram-positive spore-forming rods. While Biolog tests indicated that the three isolates belonged to the genus Bacillus, it was not possible to determine the species. Phylogenetic analysis of 16S rRNA gene hypervariant region sequences demonstrated that both NEB4 and NEB5 are Bacillus subtilis strains, and that NEB17 is a Bacillus thuringiensis strain.Key words: root nodule, endophytic bacteria, plant-growth-promoting bacteria, Bacillus subtilis, Bacillus thuringiensis.
Utility of a pre-optimized kit for random amplified polymorphic DNA in typingCandida albicans
Authors: Riederer Kathleen M , Ramanathan Jambunathan , Barczak Jeff , Baran, Jr. Joseph , Khatib Riad
Published: June 2003

The utility of a pre-optimized kit for random amplified polymorphic DNA (RAPD) was assessed in typing diverse strains of Candida albicans from epidemiologically unrelated inpatients (interpatient analysis) and in detecting clonal variations that maybe present within individual patient isolates (intrapatient analysis). Stool samples from inpatients were cultured on Inhibitory Mold agar. Nine individual colonies from all patients with [Formula: see text]9 colonies of C. albicans (n = 18) were selected, frozen, and karyotyped using CHEF genomic DNA plug kits and CHEF-DRIII. Each of the selected colonies was then analyzed by RAPD, utilizing the selected kit, with 6 primers. Interpatient analysis revealed 9 karyotypes and 17 RAPD composites. RAPD discrimination was significantly better (p < 0.001). Intrapatient analysis revealed 34 (21%) and 33 (20.4%) variants among 162 colonies tested by RAPD and karyotyping, respectively. The results were discordant in 25 variants, all with differences of 13 bands. These results illustrate that this pre-optimized kit for RAPD provides excellent discrimination of genetically unrelated strains. Its performance in delineating subtle clonal differences was comparable with karyotyping; both methods failed to detect all minor genetic variations. The ease of use and quick turnaround time of this kit offer a practical and reliable method for typing diverse strains of C. albicans, but may be inadequate for assessing microevolution.Key words: Candida albicans, karyotyping, RAPD.
Improved method for recovery of bacteriophage from large volumes of water using negatively charged microporous filters
Authors: Scott Troy M , Lukasik Jerzy , Farrah Samuel R
Published: June 2003

Current virus-recovery procedures using negatively charged microporous filters provide an inexpensive, reliable method for the recovery and detection of enteroviruses from water and wastewater; however, adjustment of the test samples to pH 3.5 to promote enterovirus adsorption results in significant inactivation of bacteriophage and an inability to simultaneously recover them from large volumes of water using this procedure. Procedures specifically designed for the detection of bacteriophage are currently in use but generally are only effective for small volumes of water. Positively charged filters can be used to recover both enteroviruses and bacteriophage from large volumes of water at neutral pH; however, the filters are expensive. The addition of manganese chloride to test solutions at pH 3.5 prior to filtration through negatively charged Filterite® filters allowed for sampling of larger volumes of water by reducing the inactivation of bacteriophage and increasing the recovery of PRD1, MS2, and naturally isolated bacteriophage by a factor of four or five when compared with recoveries from solutions without MnCl2. This method provides an inexpensive, reliable alternative to large-volume bacteriophage recovery procedures that use positively charged filters at neutral pH.Key words: bacteriophage, water, recovery, microporous filters.
A N2-fixing endophyticBurkholderiasp. associated with maize plants cultivated in Mexico
Authors: Estrada Paulina , Mavingui Patrick , Cournoyer Benoit , Fontaine Fanette , Balandreau Jacques , Caballero-Mellado Jesus
Published: June 2003

In the frame of a survey of potentially endophytic N2-fixing Burkholderia associated with maize in Mexico, its country of origin, the soil of an indigenous maize field near Oaxaca was studied. Under laboratory conditions, plant seedlings of two ancient maize varieties were used as a trap to select endophyte candidates from the soil sample. Among the N2fixers isolated from inside plant tissues and able to grow on PCAT medium, the most abundant isolates belonged to genus Burkholderia (API 20NE, rrs sequences). Representative isolates obtained from roots and shoots of different plants appeared identical (rrs and nifH RFLP), showing that they were closely related. In addition, their 16S rDNA sequences differed from described Burkholderia species and, phylogenetically, they constituted a separate deep-branching new lineage in genus Burkholderia. This indicated that these isolates probably constituted a new species. An inoculation experiment confirmed that these N2-fixing Burkholderia isolates could densely colonize the plant tissues of maize. More isolates of this group were subsequently obtained from field-grown maize and teosinte plants. It was hypothesized that strains of this species had developed a sort of primitive symbiosis with one of their host plants, teosinte, which persisted during the domestication of teosinte into maize.Key words: endophytic bacteria, nitrogen-fixation, Zea mays, Burkholderia.
Hydrophobicity development, alkane oxidation, and crude-oil emulsification in a Rhodococcus species
Authors: Bredholt Harald , Bruheim Per , Potocky Martin , Eimhjellen Kjell
Published: June 2003

The relationship between the phenomena alkane oxidation, extreme hydrophobicity of the cell surface, and crude-oil emulsification in Rhodococcus sp. strain 094 was investigated. Compounds that induce the emulsifying ability simultaneously induced the cytochrome P450-containing alkane oxidizing system and the transition from low to high cell-surface hydrophobicity. Exposed to inducers of crude-oil emulsification, the cells developed a strong hydrophobic character during exponential growth, which was rapidly lost when entering stationary phase. The loss in hydrophobicity coincided in time with the crude-oil emulsification, indicating that the components responsible for the formation of cell-surface hydrophobicity act as excellent emulsion stabilisers only after release from the cells. Rhodococcus sp. strain 094 possessed three distinct levels of cell-surface hydrophobicity. One level of low hydrophobicity was characteristic of cells in late stationary phase and was independent of growth substrate. A second and more hydrophobic level was observed for cells in exponential phase grown on water-soluble substrates, while a third level, characterised by extreme cell hydrophobicity, was observed for cells in exponential phase cultivated on hydrophobic substrates such as hexadecane. The production of the oil-emulsifying agents seems to require external sources of nitrogen and phosphate.Key words: petroleum, Rhodococcus, seawater, bacteria, bioremediation.
Purification and characterization of an alkaline serine endopeptidase from a feather-degradingXanthomonas maltophiliastrain
Authors: De Toni C H , Richter M F , Chagas J R , Henriques J AP , Termignoni C
Published: June 2003

A keratinolytic Xanthomonas maltophilia strain (POA-1), cultured on feather meal broth, using keratin as its sole source of carbon and nitrogen, secretes several extracellular peptidases. The major serine peptidase was purified to homogeneity by a five-step procedure. Its purity was evaluated by capillary zone electrophoresis. This enzyme has a molecular mass of 36 kDa, an optimum pH of 9.0, and an optimum temperature of 60°C. The inhibitory profile using protease inhibitors shows that this enzyme is a serine endopeptidase. Besides keratin, the enzyme is active upon the substrates azokeratin, azocasein, and the following fluorogenic peptide substrates: Abz-Leu-Gly-Met-Ile-Ser-Leu-Met-Lys-Arg-Pro-Gln-EDDnp, Abz-Lys-Leu-Cys(SBzl)-Gly-Pro-Lys-Gln-EDDnp, and Abz-Lys-Pro-Cys(SBzl)-Phe-Ser-Lys-Gln-EDDnp.Key words: serine endopeptidase, Xanthomonas maltophilia, keratinase, alkaline endopeptidase.
Analyses of microbial activity in biomass-recycle reactors using denaturing gradient gel electrophoresis of 16S rDNA and 16S rRNA PCR products
Authors: Morgan Christine A , Hudson Andre , Konopka Allan , Nakatsu Cindy H
Published: June 2003

The relationship between mixed microbial community structure and physiology when grown under substrate-limited conditions was investigated using continuous-flow bioreactors with 100% biomass recycle. Community structure was analyzed by denaturing gradient gel electrophoresis (DGGE) of the PCR and RT-PCR amplified V3 region of 16S rDNA and 16S rRNA templates, respectively. Comparisons were made of communities exposed to different types of transient conditions (e.g., long- and short-term starvation, increasing nutrients). With progressively more stringent substrate limitation over time, the specific content of community RNA declined by more than 10-fold and closely followed the decline in specific growth rate. In contrast, the DNA content was variable (up to 3-fold differences) and did not follow the same trend. Cluster analysis of the presence or absence of individual bands indicated that the fingerprints generated by the two templates were different, and community response was first observed in the rRNA fraction. However, both the rDNA and rRNA fingerprints provided a picture of temporal population dynamics. Dice similarity coefficients gave a quantitative measure of the differences and changes between the communities. In comparison, standard cultivation techniques yielded only a quarter of the phylotypes detected by DGGE, but included the most dominant population based on rRNA. Nucleotide-sequence analyses of the almost complete 16S rRNA genes of these isolates place them in the same group of organisms that is typically cultivated from environmental samples: α, β, and γ Proteobacteria and the high GC and the low GC Gram-positive divisions.Key words: 16S rRNA, DGGE, community analysis, biomass-recycle reactor.
The role of melanin in the antagonistic interaction between the apple scab pathogenVenturia inaequalisandMicrosphaeropsis ochracea
Authors: Bassam Souad El , Benhamou Nicole , Carisse Odile
Published: June 2003

The objective of this study was to examine the role of melanin in the interaction between the mycoparasite Microsphaeropsis ochracea and the apple scab pathogen Venturia inaequalis. Melanin was extracted from the cell wall of the pathogen and its chemical and physical properties determined on the basis of biochemical tests and visible and infrared spectra. The physical and chemical characteristics of V. inaequalis melanin were similar to the those of synthetic dihydroxyphenylalanine (DOPA) melanin. Precursors of the four known melanin biosynthetic pathways were tested for their ability to restore the pigmentation of an albino strain of V. inaequalis. Scytalone, an intermediate of the 1,8-dihydroxynaphthalene (DHN) pathway, was the only precursor to restore the dark-brown pigmentation. Tricyclazole and pyroquilon, two antipenetrant fungicides, specific inhibitors of DHN melanin synthesis in Pyricularia oryzae, were used to confirm the melanin pathway in V. inaequalis wild type. A reddish-brown pigment was obtained due to the accumulation of shunt products of the DHN melanin pathway instead of a dark-brown pigment, suggesting that the melanin extracted from V. inaequalis was a DHN melanin. Furthermore, growth of an albino mutant of V. inaequalis on scytalone-amended medium resulted in the formation of dark granules similar to those seen in wild-type isolates. Transmission electron microscopic observations of M. ochracea grown in the presence of melanin showed that the granules accumulated gradually along fungal cell walls to form a uniform dark coating.Key words: fungal interaction, biological control, mycoparasitism, apple scab disease.
Review / SynthèseA review of drinking-water-associated endotoxin, including potential routes of human exposure
Authors: Anderson William B , Slawson Robin M , Mayfield Colin I
Published: June 2003

In the past decade efforts have been made to reduce the formation of harmful disinfection byproducts during the treatment and distribution of drinking water. This has been accomplished in part by the introduction of processes that involve the deliberate encouragement of indigenous biofilm growth in filters. In a controlled environment, such as a filter, these biofilms remove compounds that would otherwise be available as disinfection byproduct precursors or support uncontrolled biological activity in distribution systems. In the absence of exposure to chlorinated water, most biofilm bacteria are gram negative and have an outer layer that contains endotoxin. To date, outbreaks of waterborne endotoxin-related illness attributable to contamination of water used in hemodialysis procedures have been only infrequently documented, and occurrences linked to ingestion or through dermal abrasions could not be located. However, a less obvious conduit, that of inhalation, has been described in association with aerosolized water droplets. This review summarizes documented drinking-water-associated incidents of endotoxin exposure attributable to hemodialysis and inhalation. Typical endotoxin levels in water and conditions under which substantial quantities can enter drinking water distribution systems are identified. It would appear that endotoxin originating in tap water can be inhaled but at present there is insufficient information available to quantify potential health risks.Key words: endotoxin, lipopolysaccharide, LPS, drinking water.
Increasing fermentation efficiency at high sugar concentrations by supplementing an additional source of nitrogen during the exponential phase of the tequila fermentation process
Authors: Arrizon Javier , Gschaedler Anne
Published: June 2003

In the tequila industry, fermentation is traditionally achieved at sugar concentrations ranging from 50 to 100 g·L1. In this work, the behaviour of the Saccharomyces cerevisiae yeast (isolated from the juices of the Agave tequilana Weber blue variety) during the agave juice fermentation is compared at different sugar concentrations to determine if it is feasible for the industry to run fermentation at higher sugar concentrations. Fermentation efficiency is shown to be higher (above 90%) at a high concentration of initial sugar (170 g·L1) when an additional source of nitrogen (a mixture of amino acids and ammonium sulphate, different than a grape must nitrogen composition) is added during the exponential growth phase.Key words: Saccharomyces cerevisiae, fermentation efficiency, nitrogen source, tequila.
Effect of fusaric acid and phytoanticipins on growth of rhizobacteria andFusarium oxysporum
Authors: Landa Blanca B , Cachinero-Díaz Juana M , Lemanceau Philippe , Jiménez-Díaz Rafael M , Alabouvette Claude
Published: June 2003

Suppression of soilborne diseases by biocontrol agents involves complex interactions among biocontrol agents and the pathogen and between these microorganisms and the plant. In general, these interactions are not well characterized. In this work, we studied (i) the diversity among strains of fluorescent Pseudomonas spp., Bacillus spp., and Paenibacillus sp. for their sensitivity to fusaric acid (FAc) and phytoanticipins from different host plants, (ii) the diversity of pathogenic and nonpathogenic Fusarium oxysporum isolates for their sensitivity to phytoanticipins, and (iii) the influence of FAc on the production of pyoverdine by fluorescent Pseudomonas spp. tolerant to this compound. There was a great diversity in the response of the bacterial strains to FAc; however, as a group, Bacillus spp. and Paenibacillus macerans were much more sensitive to FAc than Pseudomonas spp. FAc also affected production of pyoverdine by FAc-tolerant Pseudomonas spp. strains. Phytoanticipins differed in their effects on microbial growth, and sensitivity to a phytoanticipin varied among bacterial and fungal strains. Biochanin A did not affect growth of bacteria, but coumarin inhibited growth of Pseudomonas spp. strains and had no effect on Bacillus circulans and P. macerans. Conversely, tomatine inhibited growth of B. circulans and P. macerans. Biochanin A and tomatine inhibited growth of three pathogenic isolates of F. oxysporum but increased growth of three nonpathogenic F. oxysporum isolates. Coumarin inhibited growth of all pathogenic and nonpathogenic F. oxysporum isolates. These results are indicative of the complex interactions that can occur among plants, pathogens, and biological control agents in the rhizosphere and on the root surface. Also, these results may help to explain the low efficacy of some combinations of biocontrol agents, as well as the inconsistency in achieving disease suppression under field conditions.Key words: biocontrol, pyoverdines, fluorescent Pseudomonas spp., Bacillus spp., Paenibacillus spp., plantmicrobe interactions.
Soil and plant effects on microbial community structure
Authors: Buyer Jeffrey S , Roberts Daniel P , Russek-Cohen Estelle
Published: June 2003

We investigated the effects of two different plant species (corn and soybean) and three different soil types on microbial community structure in the rhizosphere. Our working hypothesis was that the rhizosphere effect would be strongest on fast-growing aerobic heterotrophs, while there would be little or no rhizosphere effect on oligotrophic and other slow-growing microorganisms. Culturable bacteria and fungi had larger population densities in the rhizosphere than in bulk soil. Communities were characterized by soil fatty acid analysis and by substrate utilization assays for bacteria and fungi. Fatty acid analysis revealed a very strong soil effect but little plant effect on the microbial community, indicating that the overall microbial community structure was not affected by the rhizosphere. There was a strong rhizosphere effect detected by the substrate utilization assay for fast-growing aerobic heterotrophic bacterial community structure, with soil controls and rhizosphere samples clearly distinguished from each other. There was a much weaker rhizosphere effect on fungal communities than on bacterial communities as measured by the substrate utilization assays. At this coarse level of community analysis, the rhizosphere microbial community was impacted most by soil effects, and the rhizosphere only affected a small portion of the total bacteria.Key words: rhizosphere, microbial community, fatty acid, substrate utilization.
Strategies used by rhizobia to lower plant ethylene levels and increase nodulation
Authors: Ma Wenbo , Penrose Donna M , Glick Bernard R
Published: June 2003

Agriculture depends heavily on biologically fixed nitrogen from the symbiotic association between rhizobia and plants. Molecular nitrogen is fixed by differentiated forms of rhizobia in nodules located on plant roots. The phytohormone, ethylene, acts as a negative factor in the nodulation process. Recent discoveries suggest several strategies used by rhizobia to reduce the amount of ethylene synthesized by their legume symbionts, decreasing the negative effect of ethylene on nodulation. At least one strain of rhizobia produces rhizobitoxine, an inhibitor of ethylene synthesis. Active 1-aminocyclopropane-1-carboxylate (ACC) deaminase has been detected in a number of other rhizobial strains. This enzyme catalyzes the cleavage of ACC to α-ketobutyrate and ammonia. It has been shown that the inhibitory effect of ethylene on plant root elongation can be reduced by the activity of ACC deaminase.Key words: rhizobia, nodulation, ethylene, ACC deaminase, rhizobitoxine.
Toxigenic diversity of two different RAPD groups ofStachybotrys chartarumisolates analyzed by potential for trichothecene production and for boar sperm cell motility inhibition
Authors: Peltola J , Niessen L , Nielsen K F , Jarvis B B , Andersen B , Salkinoja-Salonen M , Möller E M
Published: June 2003

Thirty-one isolates of Stachybotrys chartarum from indoor and outdoor environments were analyzed for the presence of the trichodiene synthase (Tri5) gene, trichothecenes, boar sperm cell motility inhibition, and randomly amplified polymorphic DNA banding patterns (RAPDs). Twenty-two S. chartarum isolates tested positive for the Tri5 gene and nine were negative when tested using novel Tri5 gene-specific PCR primer pair. The Tri5 gene positive isolates contained satratoxins (five isolates) or the simple trichothecene, trichodermol (11 isolates). The Tri5 gene negative isolates did not produce satratoxins or trichodermol. Nineteen S. chartarum isolates, distributed among the Tri5 gene negative and positive groups, inhibited boar spermatozoan motility at concentrations of [Formula: see text]60 μg of crude cell extract/mL. The inhibition of motility was independent of satratoxins or atranones. Unweighted pair group method of arithmetic averages (UPGMA) cluster analysis of RAPD fragments clustered the 31 S. chartarum isolates in two distinct groups designated as RAPD groups 1 and 2. The grouping of S. chartarum isolates obtained by UPGMA cluster analysis of RAPD fragments was identical to the grouping obtained by Tri5 gene-specific PCR. This indicates that the S. chartarum isolates belonging to different groups were genetically distinct in a much wider area than just the Tri5 gene.Key words: boar sperm cell motility inhibition, RAPD, Stachybotrys chartarum, toxicity, trichothecene, trichodiene synthase (Tri5) gene.
Fixed points via a generalized local commutativity: the compactcase
Authors: Jungck Gerald F.
Published: June 2003

In an earlier paper, the concept of semigroups of self‐maps which
are nearly commutative at a function g : X → X was introduced. We now continue the investigation, but with emphasis
on the compact case. Fixed‐point theorems for such semigroups are
obtained in the setting of semimetric and metric spaces.
On finitely equivalent continua
Authors: Charatonik Janusz J.
Published: June 2003

For positive integers m and n, relations between (hereditary)
m‐ and n‐equivalence are studied, mostly for arc‐like
continua. Several structural and mapping problems concerning
(hereditarily) finitely equivalent continua are formulated.
Composition operators from the Bloch space into the spaces QT
Authors: Wu Pengcheng , Wulan Hasi
Published: June 2003

Suppose that φ(z) is an analytic self‐map of the unit disk Δ. We consider the boundedness of the composition operator Cφ from Bloch space ℬ into the spaces QT (QT,0) defined by a nonnegative, nondecreasing function T(r) on 0 ≤ r < ∞.