bluuebunny/crossref_metadata_2025 huggingface dataset:
FADD and its Phosphorylation
Authors: Zhang Jing , Zhang Dapeng , Hua Zichun
Published: November 2004

The adaptor protein FADD is essential for apoptosis induced by 'death receptors', mediating aggregation and autocatalytic activation of caspase‐8. Surprisingly, FADD is also involved in regulating T and B cell development. Accumulating evidences now suggest that FADD and its phosphorylation have additional roles in controlling pathways of cellular activation and proliferation, while the kinase modifying FADD phosphorylation is still unidentified. The cellular localization of FADD may also contribute to define FADD's role in apoptosis or proliferation. FADD may be a pivotal molecule which coupling the opposite cell processes of proliferation and apoptosis. FADD, probably modulated by phosphorylation, may function as a 'cell renewal set point' co‐regulating proliferation and apoptosis in parallel. IUBMB Life, 56: 395‐401, 2004
The Central Role of Perilipin A in Lipid Metabolism and Adipocyte Lipolysis
Authors: Tansey John , Sztalryd Carole , Hlavin Erica , Kimmel Alan , Londos Constantine
Published: November 2004

The related disorders of obesity and diabetes are increasing to epidemic proportions. The role of neutral lipid storage and hydrolysis, and hence the adipocyte, is central to understanding this phenomenon. The adipocyte holds the major source of stored energy in the body in the form of triacylglycerols (TAG). It has been known for over 35 years that the breakdown of TAG and release of free (unesterified) fatty acids and glycerol from fat tissue can be regulated by a cAMP‐mediated process. However, beyond the initial signaling cascade, the mechanistic details of this lipolytic reaction have remained unclear. Work in recent years has revealed that both hormone‐sensitive lipase (HSL), generally thought to be the rate‐limiting enzyme, and perilipin, a lipid droplet surface protein, are required for optimal lipid storage and fatty acid release. There are multiple perilipin proteins encoded by mRNA splice variants of a single perilipin gene. The perilipin proteins are polyphosphorylated by protein kinase A and phosphorylation is necessary for translocation of HSL to the lipid droplet and enhanced lipolysis. Hence, the surface of the lipid storage droplet has emerged as a central site of regulation of lipolysis. This review will focus on adipocyte lipolysis with emphasis on hormone signal transduction, lipolytic enzymes, the lipid storage droplet, and fatty acid release from the adipocyte. IUBMB Life, 56: 379‐385, 2004
Pronator Quadratus Flap for Burn Reconstruction
Authors: Marshall M P. , Gutheil J P.
Published: November 2004

Full-thickness skin loss in the distal volar forearm presents a challenge to the burn surgeon. Two cases are presented in which a pronator quadratus muscle flap with split-thickness skin was used to cover the underlying tendons and nerves. The unique vascular perfusion makes this a useful and predictable transfer.
Gas Fireplace Contact Burns in Young Children
Authors: Zettel Julie C. , Khambalia Amina , Barden Wendy , Murthy Trisha , Macarthur Colin
Published: November 2004

Contact burns from domestic appliances are common in young children. Recently, gas fireplaces have been recognized as a potential cause of contact burns in young children. We sought to quantify the frequency of gas fireplace contact burns in young children, to identify the etiology of contact, to describe the clinical presentation, and to describe clinical outcomes. Children with gas fireplace contact burn injuries presenting to The Hospital for Sick Children in Toronto (1999–2002) were identified using three data sources: the Canadian Hospitals Injury Reporting and Prevention Program Database, the Burn Unit Registry, and the Rehabilitation Services Database. Demographic, clinical, and outcomes data were collected on all children. During the 4-year study period, 27 children presented to the hospital because of a gas fireplace contact burn (approximately 9% of all contact burns). The median age of the children was 14 months (range, 8–36 months), with 16 boys (59%). Most children were burned in their own home. With regard to etiology, 10 children (37%) lost their balance near the fireplace, 2 (7%) walked too close to the glass front, and 8 (30%) touched the glass front out of curiosity. Almost half (44%) of the children burned the palms and digits of both hands. The median total burn surface area was 1% (range, 0.2–2.5%). In total, 30% of children were admitted to hospital, and 11% required skin grafts. All children had full wound closure after 4 to 43 days. Given the etiology of these burns (loss of balance or curiosity), passive prevention, such as barriers or changes in the composition of glass panels, may be the most effective approach to combat them.
Circulating Leptin and Cortisol After Burn Injury: Loss of Diurnal Pattern
Authors: Hobson Kristina G. , Havel Peter J. , McMurtry Addison L. , Lawless Mary Beth , Palmieri Tina L. , Greenhalgh David D.
Published: November 2004

Leptin, a hormone involved in appetite and metabolic energy expenditure, could have a role in the reduced appetite and/or energy expenditure after burn injury. In this study, the diurnal pattern of circulating leptin concentrations was compared with body mass index (BMI), sex, glucose, insulin, and the diurnal cortisol rhythm in burn patients. Plasma samples were collected at 12:00 pm and 02:00 am from severely burned adults and children. Circulating leptin, insulin, and cortisol were measured by radioimmunoassay. Results were compared with previously published data from healthy control subjects. Overall, plasma leptin levels were lower in burn patients (5.7 ± 1.2 ng/mL) compared with control subjects (10.5 ± 1.7 ng/mL, P = .02). The normal nocturnal increase of circulating leptin concentrations observed in control subjects was completely absent in burn patients. Cortisol levels were higher in burn patients (20.4 ± 1.0 mg/dL) than in control subjects (9.8 ± 1.6mg/dL, P < .0001) and the normal circadian decrease of circulating cortisol levels was markedly blunted in burn patients. Plasma cortisol did not correlate with circulating leptin levels. Plasma insulin and plasma glucose levels were significantly elevated in burn patients and the insulin:glucose ratio was dramatically increased compared with control subjects. Patients with burn injuries exhibited significantly decreased circulating leptin levels. This decrease may be the result of marked insulin resistance, as suggested by the elevated insulin to glucose ratio in burn patients. The loss of the diurnal pattern in burn patients is likely to result from the continuous nutritional supplementation. Because low leptin levels should induce appetite, burn-related anorexia is probably controlled by other regulatory systems.
Electrical Injuries: A 20-Year Review
Authors: Arnoldo Brett D. , Purdue Gary F. , Kowalske Karen , Helm Phala A. , Burris Agnes , Hunt John L.
Published: November 2004

Electrical injuries continue to present problems with devastating complications and long-term socioeconomic impact. The purpose of this study is to review one institution's experience with electrical injuries. From 1982 to 2002, there were 700 electric injury admissions. A computerized burn registry was used for data collection and analysis. Of these injuries, 263 were high voltage (≥1000 V), 143 were low voltage (<1000 V), 277 were electric arc flash burns, and 17 were lightning injuries. Mortality was highest in the lightning strikes (17.6%) compared with the high voltage (5.3%) and low voltage (2.8%) injuries, and mortality was least in electric arc injuries without passage of current through the patient (1.1%). Complications were most common in the high-voltage group. Mean length of stay was longest in this group (18.9 ± 1.4 days), and the patients in this group also required the most operations (3 ± 0.2). Work-related activity was responsible for the majority of these high-voltage injuries, with the most common occupations being linemen and electricians. These patients tended to be younger men in the prime of their working lives. Electrical injuries continue to make up an important subgroup of patients admitted to burn centers. High-voltage injuries in particular have far reaching social and economic impact largely because of the patient population at greatest risk, that is, younger men at the height of their earning potential. Injury prevention, although appropriate, remains difficult in this group because of occupation-related risk.
Telemedicine Follow-up of Burns: Lessons Learned from the First Thousand Visits
Authors: Nguyen Lan T. , Massman Nancy J. , Franzen Beth J. , Ahrenholz David H. , Sorensen Nicholas W. , Mohr William J. , Solem Lynn D.
Published: November 2004

Telemedicine is an evolving technology that is used for health education, health care administration, and health care distribution. The potential benefits of telemedicine include a decrease in travel expenses, improved continuity of care, and increased access to specialized consultants, thus meeting the needs of patients, practitioners, and communities. Telemedicine has many evolving applications, including improved access to health care in medically underserved and rural areas. Regions Burn Center assessed the efficacy and efficiency of burn visits via telemedicine and identified the barriers and benefits specific to burn care. Information regarding travel costs and financial data were evaluated from a total of 1000 burn follow-up visits with 294 patients via telemedicine during a 5-year interval. Our results indicate that telemedicine burn visits are a cost-effective clinical alternative for the patient. However, telemedicine can be a financial burden to health care systems and inefficient for health care providers.
The Use of Haloperidol and Associated Complications in the Agitated, Acutely Ill Pediatric Burn Patient
Authors: Ratcliff Stephen L. , Meyer Walter J. , Cuervo Luis J. , Villarreal Cynthia , Thomas Christopher R. , Herndon David N.
Published: November 2004

The use of haloperidol to induce sedation and control agitation in the acutely ill adult patient has been well documented. There are few reports, however, of the use of this neuroleptic agent to control the severe delirium and agitation that may occur in critically ill pediatric patients or acute pediatric patients suffering from burn wounds. We assessed the effectiveness and safety of the use of haloperidol by completing a retrospective chart review of 855 acutely ill children treated consecutively during the period from April 1999 to May 2002, during which time 26 children received haloperidol. The safe use of haloperidol was assessed by documenting any adverse effects or reactions observed after the administration of the drug. Of patients given haloperidol, 23% had adverse effects. This result suggests that the use of haloperidol to treat the acutely agitated and delirious pediatric burn patients is fraught with a number of difficulties and is not completely safe and effective.
A new Bacillus cereus DNA-binding protein, HlyIIR, negatively regulates expression of B. cereus haemolysin II
Authors: Budarina Zhanna I. , Nikitin Dmitri V. , Zenkin Nikolay , Zakharova Marina , Semenova Ekaterina , Shlyapnikov Michael G. , Rodikova Ekaterina A. , Masyukova Svetlana , Ogarkov Oleg , Baida Gleb E. , Solonin Alexander S. , Severinov Konstantin
Published: November 2004

Haemolysin II, HlyII, is one of several cytotoxic proteins produced by Bacillus cereus, an opportunistic human pathogen that causes food poisoning. The hlyII gene confers haemolytic activity to Escherichia coli cells. Here a new B. cereus gene, hlyIIR, which is located immediately downstream of hlyII and regulates hlyII expression, is reported. The deduced amino acid sequence of HlyIIR is similar to prokaryotic DNA-binding transcriptional regulators of the TetR/AcrA family. Measurements of haemolytic activity levels and of hlyII promoter activity levels using gene fusions and primer-extension assays demonstrated that, in E. coli, hlyII transcription decreased in the presence of hlyIIR. Recombinant HlyIIR binds to a 22 bp inverted DNA repeat centred 48 bp upstream of the hlyII promoter transcription initiation point. In vitro transcription studies showed that HlyIIR inhibits transcription from the hlyII promoter by binding to the 22 bp repeat and RNA polymerase, and by decreasing the formation of the catalytically competent open promoter complex.
Role of Cal, the colicin A lysis protein, in two steps of colicin A release and in the interaction with colicin A–porin complexes
Authors: Cavard Danièle
Published: November 2004

Release of colicin A was studied inEscherichia colicells that differed in expressing thecolicinAlysis protein (Cal). Pools of released and unreleased colicin A were harvested throughout colicin A induction. The amount of colicin A in each pool varied with the time of induction, allowing the definition of two sequential steps in colicin A release, one of which was dependent on Cal. Each step of colicin A release was differently affected in cells containing Cal mutants in which the N-terminal cysteine residue was substituted by either proline or threonine, preventing them from being acylated and matured. These Cal mutants were only observed indegPcells, indicating that the DegP protease cleaved the unacylated precursor of Cal. Cal was found in the insoluble fraction of the pools of released and unreleased colicin A together with the hetero-oligomers of colicin A and porins (colicins Au). The biogenesis of colicins Au was studied in temperature-sensitivesecAandsecYstrains and found to be Sec-independent, indicating that they are formed by newly synthesized colicin A binding to mature porins already incorporated in the outer membrane. Cal is a lipoprotein similar to VirB7, a constituent of the type IV secretion system. It would interact with colicins Au to constitute the colicin A export machinery.
Protein A gene expression is regulated by DNA supercoiling which is modified by the ArlS–ArlR two-component system of Staphylococcus aureus
Authors: Fournier Bénédicte , Klier André
Published: November 2004

Bacterial pathogens such as Staphylococcus aureus undergo major physiological changes when they infect their hosts, requiring the coordinated regulation of gene expression in response to the stresses encountered. Several environmental factors modify the expression of S. aureus virulence genes. This report shows that the expression of spa (virulence gene encoding the cell-wall-associated protein A) is down-regulated by high osmolarity (1 M NaCl, 1 M KCl or 1 M sucrose) in the wild-type strain and upregulated by novobiocin (a DNA gyrase inhibitor that relaxes DNA). A gyrB142 allele corresponding to a double mutation in the B subunit of DNA gyrase relaxed DNA and consequently induced spa expression, confirming that spa expression is regulated by DNA topology. Furthermore, in the presence of novobiocin plus 1 M NaCl, a good correlation was observed between DNA supercoiling and spa expression. The ArlS–ArlR two-component system is involved in the expression of virulence genes such as spa. Presence of an arlRS deletion decreased the effect of DNA supercoiling modulators on spa expression, suggesting that active Arl proteins are necessary for the full effect of DNA gyrase inhibitors and high osmolarity on spa expression. Indeed, evidence is provided for a relationship between the arlRS deletion and topological changes in plasmid DNA.
Characterization of a dam mutant of Haemophilus influenzae Rd
Authors: Zaleski Piotr , Piekarowicz Andrzej
Published: November 2004

The gene encoding Dam methyltransferase ofHaemophilus influenzaewas mutagenized by the insertion of a chloramphenicol-resistance cassette into the middle of the Dam coding sequence. This mutant construct was introduced into theH. influenzaechromosome by transformation and selection for CamRtransformants. The authors have shown that several phenotypic properties, resistance to antibiotics, dyes and detergent as well as efficiency of transformation, depend on the Dam methylation state of the DNA. Although the major role of the methyl-directed mismatch repair (MMR) system is to repair postreplicative errors, it seems that inH. influenzaeits effect is more apparent in repairing DNA damage caused by oxidative compounds. In thedammutant treated with hydrogen peroxide, MMR is not targeted to newly replicated DNA strands and therefore mismatches are converted into single- and double-strand DNA breaks. This is shown by the increased peroxide sensitivity of thedammutant and the finding that the sensitivity can be suppressed by amutHmutation inactivating MMR. In thedammutant treated with nitrofurazone the resulting damage is not converted into DNA breaks but the high sensitivity is also suppressed by amutHmutation.
Novel organization of genes in a phthalate degradation operon of Mycobacterium vanbaalenii PYR-1
Authors: Stingley Robin L. , Brezna Barbara , Khan Ashraf A. , Cerniglia Carl E.
Published: November 2004

Mycobacterium vanbaaleniiPYR-1 is capable of degrading polycyclic aromatic hydrocarbons (PAHs) to ring cleavage metabolites. This study identified and characterized a putative phthalate degradation operon in theM. vanbaaleniiPYR-1 genome. A putative regulatory protein (phtR) was encoded divergently with five tandem genes: phthalate dioxygenase large subunit (phtAa), small subunit (phtAb), phthalate dihydrodiol dehydrogenase (phtB), phthalate dioxygenase ferredoxin subunit (phtAc) and phthalate dioxygenase ferredoxin reductase (phtAd). A 6·7 kbEcoRI fragment containing these genes was cloned intoEscherichia coliand converted phthalate to 3,4-dihydroxyphthalate. Homologues to the operon region were detected in a number of PAH-degradingMycobacteriumspp. isolated from various geographical locations. The operon differs from those of other Gram-positive bacteria in both the placement and orientation of the regulatory gene. In addition, theM. vanbaaleniiPYR-1phtoperon contains no decarboxylase gene and none was identified within a 37 kb region containing the operon. This study is the first report of a phthalate degradation operon inMycobacteriumspp.
Comparative proteome analysis of Mycobacterium tuberculosis grown under aerobic and anaerobic conditions
Authors: Starck Joakim , Källenius Gunilla , Marklund Britt-Inger , Andersson Dan I. , Åkerlund Thomas
Published: November 2004

Data are presented from two-dimensional (2-D) PAGE analysis ofMycobacterium tuberculosisstrain Harlingen grown during aerobic and anaerobic culture, according to a modified Wayne dormancy model.M. tuberculosiscultures were grown to the transition point between exponential growth and stationary phase in the presence of oxygen (7 days) and then part of the cultures was shifted to anaerobic conditions for 16 days. Growth declined similarly during aerobic and anaerobic conditions, whereas the ATP consumption rapidly decreased in the anaerobic cultures. 2-D PAGE revealed 50 protein spots that were either unique to, or more abundant during, anaerobic conditions and 16 of these were identified by MALDI-TOF. These proteins were theα-crystalline homologue (HspX), elongation factor Tu (Tuf), GroEL2, succinyl-CoA : 3-oxoacid-CoA transferase (ScoB), mycolic acid synthase (CmaA2), thioredoxin (TrxB2),β-ketoacyl-ACP synthase (KasB),l-alanine dehydrogenase (Ald), Rv2005c, Rv2629, Rv0560c, Rv2185c and Rv3866. Some protein spots were found to be proteolytic fragments, e.g. HspX and GroEL2. These data suggest thatM. tuberculosisinduces expression of about 1 % of its genes in response to dormancy.
The complete sequences of plasmids pB2 and pB3 provide evidence for a recent ancestor of the IncP-1β group without any accessory genes
Authors: Heuer H. , Szczepanowski R. , Schneiker S. , Pühler A. , Top E. M. , Schlüter A.
Published: November 2004

The nucleotide sequences of the broad-host-range antibiotic resistance plasmids pB2 (61 kb) and pB3 (56 kb), which were isolated from a wastewater treatment plant, were determined and analysed. Both have a nearly identical IncP-1βbackbone, which diverged early from the sequenced IncP-1βplasmids R751, pB10, pJP4, pADP1 and pUO1. In contrast to the latter plasmids, the pB2 and pB3 backbone does not seem to have undergone any deletions. The complete partition geneparAis located downstream of the mating pair formation (trb) module. A 14·4 kb or 19·0 kb mobile genetic element is present betweentraCandparAof pB3 and pB2, respectively. This region is typical for insertions in IncP-1βplasmids, but the insertion site is unique. Both elements differ only by a duplication in pB2 of atetA(C)–tetR–tnpAIS26fragment. The 5 bp target site duplication and the 26 bp inverted repeats flanking the mobile genetic elements are still intact, indicating that the insertion occurred recently. The element consists of three nested transposable elements: (i) a relict of a Tn402-like transposon with a gene for a new class Dβ-lactamase (blaNPS-2); (ii) within that, another Tn402-like element with a class 1 integron harbouring the gene cassettescmlA1for a chloramphenicol efflux protein andaadA2encoding a streptomycin/spectinomycin adenylyltransferase, and a copy of IS6100; (iii) into the integrase geneintI1a tetracycline resistance moduletetA(C)–tetRflanked by copies of IS26is inserted. Interestingly, in contrast to all other IncP-1βplasmids analysed so far, theoriVregion betweentrfAandklcAis not interrupted by accessory genes, and there is no indication that previously inserted accessory genes have subsequently been deleted. The geneskluABare also missing in that region and should thus be considered acquired genes. These findings, together with the fact that IncP-1βplasmids acquired accessory elements at various positions in the backbone, suggest that IncP-1βplasmids without any accessory genes exist in microbial communities. They must occasionally acquire accessory genes by transposition events, resulting in those plasmids that have been found based on selectable phenotypic traits.
Antibiotic multiresistance plasmid pRSB101 isolated from a wastewater treatment plant is related to plasmids residing in phytopathogenic bacteria and carries eight different resistance determinants including a multidrug transport system
Authors: Szczepanowski Rafael , Krahn Irene , Linke Burkhard , Goesmann Alexander , Pühler Alfred , Schlüter Andreas
Published: November 2004

Ten different antibiotic resistance plasmids conferring high-level erythromycin resistance were isolated from an activated sludge bacterial community of a wastewater treatment plant by applying a transformation-based approach. One of these plasmids, designated pRSB101, mediates resistance to tetracycline, erythromycin, roxythromycin, sulfonamides, cephalosporins, spectinomycin, streptomycin, trimethoprim, nalidixic acid and low concentrations of norfloxacin. Plasmid pRSB101 was completely sequenced and annotated. Its size is 47 829 bp. Conserved synteny exists between the pRSB101 replication/partition (rep/par) module and the pXAC33-replicon from the phytopathogenXanthomonas axonopodispv.citri. The second pRSB101 backbone module encodes a three-Mob-protein type mobilization (mob) system with homology to that of IncQ-like plasmids. Plasmid pRSB101 is mobilizable with the help of the IncP-1αplasmid RP4 providing transfer functionsin trans. A 20 kb resistance region on pRSB101 is located within an integron-containing Tn402-like transposon. The variable region of the class 1 integron carries the genesdhfr1for a dihydrofolate reductase,aadA2for a spectinomycin/streptomycin adenylyltransferase andblaTLA-2for a so far unknown Ambler class A extended spectrumβ-lactamase. The integron-specific 3′-segment (qacEΔ1-sul1-orf5Δ) is connected to a macrolide resistance operon consisting of the genesmph(A) (macrolide 2′-phosphotransferase I),mrx(hydrophobic protein of unknown function) andmphR(A) (regulatory protein). Finally, a putative mobile element with the tetracycline resistance genestetA(tetracycline efflux pump) andtetRwas identified upstream of the Tn402-specific transposase genetniA. The second ‘genetic load’ region on pRSB101 harbours four distinct mobile genetic elements, another integron belonging to a new class and footprints of two more transposable elements. A tripartite multidrug (MDR) transporter consisting of an ATP-binding-cassette (ABC)-type ATPase and permease, and an efflux membrane fusion protein (MFP) of the RND-family is encoded between the replication/partition and the mobilization module. Homologues of the macrolide resistance genesmph(A),mrxandmphR(A) were detected on eight other erythromycin resistance-plasmids isolated from activated sludge bacteria. Plasmid pRSB101-likerepAamplicons were also obtained from plasmid-DNA preparations of the final effluents of the wastewater treatment plant indicating that pRSB101-like plasmids are released with the final effluents into the environment.
A virulence-associated gene microarray: a tool for investigation of the evolution and pathogenic potential of Staphylococcus aureus
Authors: Saunders Nicholas A. , Underwood Anthony , Kearns Angela M. , Hallas Gillian
Published: November 2004

An oligonucleotide probe microarray for investigation of the evolution of epidemicStaphylococcus aureusstrains has been constructed. The array comprises 383 probes based on virulence-associated genes present in four key strains. Twelve strains including seven for which the complete chromosomal nucleotide sequence was available were tested on the array. Twenty-six per cent of the probes were able to differentiate between strains to give a minimum of two gene differences between pairs. A gene difference distance tree based on the array data had approximately the same topology as one prepared using concatenated MLST sequences. Differences in the topologies of these trees were found to indicate that large-scale recombination events had occurred during the evolution of the species. One such occurrence appears to have been a key event in the genesis of the EMRSA-15 clone (ST22) that currently represents the most prevalent methicillin-resistantS. aureus(MRSA) in the UK.
Characterization of the fibrinogen-binding surface protein Fbl of Staphylococcus lugdunensis
Authors: Mitchell Jennifer , Tristan Anne , Foster Timothy J.
Published: November 2004

The fbl gene of Staphylococcus lugdunensis encodes a protein Fbl that is 58 % identical to the clumping factor A (ClfA) of Staphylococcus aureus. The fbl gene was present in eight clinical isolates of S. lugdunensis. When Fbl was expressed on the surface of Lactococcus lactis it promoted adherence to immobilized fibrinogen and cell clumping in a fibrinogen solution. Purified recombinant Fbl region A bound to immobilized fibrinogen in a dose-dependent manner and inhibited the adherence of both Fbl-expressing and ClfA-expressing strains of L. lactis to fibrinogen. Adherence of S. lugdunensis and L. lactis Fbl+ to immobilized fibrinogen was also inhibited by rabbit anti-Fbl region A antibodies and rabbit anti-ClfA region A antibodies, as well as by human immunoglobulin with a high level of anti-ClfA antibodies. Alignment of the A domains of CflA and Fbl revealed that all of the ClfA residues implicated in binding to the γ-chain of fibrinogen are conserved in Fbl. Nevertheless Fbl had a tenfold lower affinity for fibrinogen, suggesting that sequence differences that occur elsewhere in the protein, possibly in β-strand E of domain N2, affect ligand binding.
Analysis of Pseudomonas fluorescens F113 genes implicated in flagellar filament synthesis and their role in competitive root colonization
Authors: Capdevila Silvia , Martínez-Granero Francisco M. , Sánchez-Contreras María , Rivilla Rafael , Martín Marta
Published: November 2004

The ability of plant-associated micro-organisms to colonize and compete in the rhizosphere is specially relevant for the biotechnological application of micro-organisms as inoculants. Pseudomonads are one of the best root colonizers and they are widely used in plant-pathogen biocontrol and in soil bioremediation. This study analyses the motility mechanism of the well-known biocontrol strain Pseudomonas fluorescens F113. A 6·5 kb region involved in the flagellar filament synthesis, containing the fliC, flaG, fliD, fliS, fliT and fleQ genes and part of the fleS gene, was sequenced and mutants in this region were made. Several non-motile mutants affected in the fliC, fliS and fleQ genes, and a fliT mutant with reduced motility properties, were obtained. These mutants were completely displaced from the root tip when competing with the wild-type F113 strain, indicating that the wild-type motility properties are necessary for competitive root colonization. A mutant affected in the flaG gene had longer flagella, but the same motility and colonization properties as the wild-type. However, in rich medium or in the absence of iron limitation, it showed a higher motility, suggesting the possibility of improving competitive root colonization by manipulating the motility processes.
Autogenous modulation of the Bacillus subtilis sacB–levB–yveA levansucrase operon by the levB transcript
Authors: Daguer Jean-Pierre , Geissmann Thomas , Petit-Glatron Marie-Françoise , Chambert Régis
Published: November 2004

Silencing oflevB, the second structural gene of the tricistronic levansucrase operon encoding the endolevanase LevB, decreases the level of levansucrase expression inBacillus subtilis. Conversely, independent expression oflevBgreatly stimulates operon expression. This autogenous effect is mediated by thelevBtranscript, which carries an internal sequence (5′-AAAGCAGGCAA-3′) involved in the enhancing effect.In vitro, thelevBtranscript displays an affinity for the N-terminal fragment of SacY (KD0·2 μM), the regulatory protein that prevents transcription termination of the levansucrase operon. This positive-feedback loop leads to an increase in the operon expression whenB. subtilisis growing in the presence of high sucrose concentrations. Under these conditions, extracellular levan synthesized by the fructosyl polymerase activity of levansucrase can be degraded mainly into levanbiose by the action of LevB. Levanbiose is neither taken up nor metabolized by the bacteria. This work modifies the present view of the status of levansucrase inB. subtilisphysiology.
The siderophore-mediated iron acquisition systems of Acinetobacter baumannii ATCC 19606 and Vibrio anguillarum 775 are structurally and functionally related
Authors: Dorsey Caleb W. , Tomaras Andrew P. , Connerly Pamela L. , Tolmasky Marcelo E. , Crosa Jorge H. , Actis Luis A.
Published: November 2004

TheAcinetobacter baumanniitype strain, ATCC 19606, secretes acinetobactin, a catechol siderophore highly related to the iron chelator anguibactin produced by the fish pathogenVibrio anguillarum(Listonella anguillarum). This paper reports the initial characterization of the genes and gene products involved in the acinetobactin-mediated iron-acquisition process. Insertional mutagenesis resulted in the isolation of several derivatives whose ability to grow in medium containing the iron chelator 2,2′-dipyridyl was affected. One of the insertions disrupted a gene encoding a predicted outer-membrane protein, named BauA, highly similar to FatA, the receptor for ferric anguibactin. Immunological relatedness of BauA with FatA was confirmed by Western blot analysis. Another transposon insertion was mapped to a gene encoding a protein highly similar to FatD, the permease component of the anguibactin transport system. Further DNA sequencing and nucleotide sequence analysis revealed that theseA. baumannii19606 genes are part of a polycistronic locus that contains thebauDCEBAORFs. While the translation products ofbauD, -C, -Band -Aare highly related to theV. anguillarumFatDCBA iron-transport proteins, the product ofbauEis related to the ATPase component of Gram-positive ATP-binding cassette (ABC) transport systems. This entire locus is flanked by genes encoding predicted proteins related to AngU and AngN,V. anguillarumproteins required for the biosynthesis of anguibactin. These protein similarities, as well as the structural similarity of anguibactin and acinetobactin, suggested that these two siderophores could be utilized by both bacterial strains, a possibility that was confirmed by siderophore utilization bioassays. Taken together, these results demonstrate that these pathogens, which cause serious infections in unrelated hosts, express very similar siderophore-mediated iron-acquisition systems.
The complete genomes of Lactobacillus plantarum and Lactobacillus johnsonii reveal extensive differences in chromosome organization and gene content
Authors: Boekhorst Jos , Siezen Roland J. , Zwahlen Marie-Camille , Vilanova David , Pridmore Raymond D. , Mercenier Annick , Kleerebezem Michiel , de Vos Willem M. , Brüssow Harald , Desiere Frank
Published: November 2004

The first comprehensive comparative analysis of lactobacilli was done by comparing the genomes of Lactobacillus plantarum (3·3 Mb) and Lactobacillus johnsonii (2·0 Mb). L. johnsonii is predominantly found in the gastrointestinal tract, while L. plantarum is also found on plants and plant-derived material, and is used in a variety of industrial fermentations. The L. plantarum and L. johnsonii chromosomes have only 28 regions with conservation of gene order, totalling about 0·75 Mb; these regions are not co-linear, indicating major chromosomal rearrangements. Metabolic reconstruction indicates many differences between L. johnsonii and L. plantarum: numerous enzymes involved in sugar metabolism and in biosynthesis of amino acids, nucleotides, fatty acids and cofactors are lacking in L. johnsonii. Major differences were seen in the number and types of putative extracellular proteins, which are of interest because of their possible role in host–microbe interactions. The differences between L. plantarum and L. johnsonii, both in genome organization and gene content, are exceptionally large for two bacteria of the same genus, emphasizing the difficulty in taxonomic classification of lactobacilli.
Biosurfactants produced by Pseudomonas fluorescens and soft‐rotting of harvested florets of broccoli and cauliflower
Authors: Hernandez‐Anguiano A. M. , Suslow T. V. , Leloup L. , Kado C. I.
Published: November 2004

Mini‐Tn5 transposon mutagenesis of a soft‐rotting isolate of Pseudomonas fluorescens strain 123 produced six mutant phenotypes with altered pathogenicity and inability to produce a biosurfactant involved in dispersing P. fluorescens cells in a surface aqueous environment. The mutants isolated showed in vivo growth characteristics identical to those of the wild type, but variations in their ability to reduce surface tension of water and to grow in liquid medium containing hexadecane. One of these mutants (EG3) with reduced pathogenicity on broccoli and cauliflower exhibited a restored pathogenic phenotype when complemented with a 7·1‐kb segment of P. fluorescens genomic DNA. The loss of aqueous‐surface‐tension activity in mutants suggests that a biosurfactant may contribute to pathogenicity and enhance pathogen invasion of host tissues.
Sanitation practices that inhibit reproduction of Monosporascus cannonballus in melon roots left in the field after crop termination
Authors: Radewald K. C. , Ferrin D. M. , Stanghellini M. E.
Published: November 2004

Ascospores of Monosporascus cannonballus function as primary inoculum for infection of melon roots. Previous studies demonstrated that pathogen reproduction (i.e. ascospore production) occurs on infected melon roots primarily after the crop has been terminated. Therefore, the key to maintaining low soil population densities of the pathogen is to destroy the hyphae of the pathogen in infected roots as soon as possible after crop termination, thereby inhibiting ascospore production. Results from a 3‐year field study demonstrated that, relative to the nontreated controls, an immediate postharvest application of metam sodium (applied via the drip irrigation system at 187 L ha−1) or cultivation (which lifts roots onto the surface of the soil for rapid desiccation) significantly inhibited pathogen reproduction in infected melon roots, as shown by the number of roots subsequently bearing perithecia. Additionally, ascospore populations in plots that received either the metam sodium or cultivation treatment were significantly lower (P < 0·05) than populations in the nontreated control plots at the end of the 3‐year study. These results demonstrated the efficacy of these postharvest treatments in the inhibition of pathogen reproduction and retardation of inoculum build‐up in soil.
Effect of soil amendments, intercropping and planting time in combination on the severity of cassava bacterial blight and yield in two ecozones of West Africa
Authors: Zinsou V. , Wydra K. , Ahohuendo B. , Hau B.
Published: November 2004

The severity of cassava bacterial blight at two sites in the forest‐savanna transition (FST) and dry savanna (DS) zones of West Africa were studied by assessing the effects of: (i) shift of planting date; (ii) potassium fertilizer application and mulching; (iii) intercropping cassava with sorghum or cowpea vs. cassava monoculture; and (iv) the combination of these measures. Disease severity of bacterial blight in two genotypes was generally reduced by 20–60% by late planting, without a negative effect on cassava root yield, in monocropping systems in most treatments in the FST zone (reduction in four treatments, and increase in two treatments, out of 19) and the DS zone (two of eight treatments in 1 year). Late planting led to crop failure in the DS zone in the second year. Intercropping cassava with sorghum reduced bacterial blight severity significantly, up to 80% at normal (all treatments) and late planting time (three out of six treatments) in the FST zone, and in some treatments (four out of seven) at normal planting in the DS zone. Intercropping of cassava with cowpea in the DS zone also reduced disease severity. Cassava‐sorghum intercropping generally had no effect on root yield compared with cassava monocropping at both planting times in the FST zone and provided an additional harvest of the intercrop, while yield was affected by intercropping in the DS zone at late, and in some treatments (three out of seven) at normal, planting time. Mulching and potassium treatment had no effect on disease severity, but increased or decreased root yield in some treatments in both sites. Analysis of combined data showed that cropping system, year, site, and site combined with planting date were the highest significant determinants of variation in bacterial blight development.
Eradication of plant pathogens and nematodes during composting: a review
Authors: Noble R. , Roberts S. J.
Published: November 2004

The effects of temperature–time combinations and other sanitizing factors during composting on 64 plant pathogenic fungi, plasmodiophoromycetes, oomycetes, bacteria, viruses and nematodes were reviewed. In most cases pathogen survival was determined by bioassays of unknown sensitivity and minimum detection limits of 5% infection or more. For 33 out of 38 fungal and oomycete pathogens, all seven bacterial pathogens and nine nematodes, and three out of nine plant viruses, a peak temperature of 64–70°C and duration of 21 days, were sufficient to reduce numbers to below the detection limits of the tests used. Shorter periods and/or lower temperatures than those quoted in these tests may be satisfactory for eradication, but they were not always examined in detail in composting systems. Plasmodiophora brassicae (clubroot of Brassica spp.), Fusarium oxysporum f.sp. lycopersici (tomato wilt) and Macrophomina phaseolina (dry root rot) were more temperature‐tolerant, as they survived a peak compost temperature of at least 62°C (maximum 74°C) and a composting duration of 21 days. Synchytrium endobioticum (potato wart disease) survived in water at 60°C for 2 h, but was not examined in compost. For Tobacco mosaic virus (TMV), peak compost temperatures in excess of 68°C and composting for longer than 20 days were needed to reduce numbers below detection limits. However, TMV and Tomato mosaic virus (TomMV) were inactivated over time in compost, even at temperatures below 50°C. Temperatures in excess of 60°C were achieved in different composting systems, with a wide range of organic feedstocks. The potential survival of plant pathogens in cooler zones of compost, particularly in systems where the compost is not turned, has not been quantified. This may be an important risk factor in composting plant wastes.
Determination of deoxynivalenol‐ and nivalenol‐producing chemotypes of Fusarium graminearum isolated from wheat crops in England and Wales
Authors: Jennings P. , Coates M. E. , Walsh K. , Turner J. A. , Nicholson P.
Published: November 2004

Fusarium graminearum, one of the causal agents of fusarium head blight (FHB) of wheat in the UK, can be broadly divided into two chemotypes based on the production of the 8‐ketotrichothecenes deoxynivalenol (DON) and nivalenol (NIV). DON‐producing isolates can be further distinguished on the basis of the predominant acetyl DON derivative that they produce; 3‐acetyl DON (3‐AcDON) or 15‐acetyl DON (15‐AcDON). Functional Tri13 and Tri7 are required for the production of NIV and 4‐acetyl NIV, respectively, whereas, in isolates that produce only DON and its acetylated derivatives, these genes are nonfunctional or absent. Infections caused by F. graminearum are becoming more frequent in the UK; however, it is unknown whether these represent more than one chemotype. In this study, polymerasae chain reaction (PCR) assays specific for functional and nonfunctional/deleted versions of Tri7 and Tri13 were used to characterize 101 single‐spore isolates of Fusarium graminearum as DON or NIV chemotypes. Primer sets developed to Tri3 were used to classify DON chemotypes further by the acetyl derivative produced (3‐AcDON or 15‐AcDON). Isolates were collected from 65 fields located around England and Wales between 1997 and 2002. All three chemotypes were identified from the F. graminearum population of England and Wales, with 15‐AcDON chemotypes predominating overall. All isolates characterized as 3‐ or 15‐AcDON chemotypes had nonfunctional versions of both genes. Where multiple isolates were collected from a field, mixed‐chemotype populations were identified. Variation in the number of 11‐bp repeats in Tri7 was detected among 3‐ and 15‐AcDON chemotypes. Seventy‐two of the 76 DON chemotypes (95%) were classified as 15‐AcDON producers and the remaining four isolates (5%) as 3‐AcDON producers. In all four isolates with a 3‐AcDON chemotype, Tri7 was deleted from the trichothecene gene cluster. There was no evidence of regional variation between 3‐AcDON, 15‐AcDON or NIV chemotypes within the F. graminearum population.
Dual begomovirus infections and high Bemisia tabaci populations: two factors driving the spread of a cassava mosaic disease pandemic
Authors: Colvin J. , Omongo C. A. , Maruthi M. N. , Otim‐Nape G. W. , Thresh J. M.
Published: November 2004

A cassava mosaic disease (CMD) pandemic currently affects much of East and Central Africa. To understand the factors driving the pandemic's continued spread, complementary data sets were collected from cassava plots, planted with healthy cuttings, at eight sites along a north–south transect in southern Uganda, through the pandemic's leading edge. Data were collected on virus incidence, symptom severity, populations of the whitefly vector, Bemisia tabaci, their infectivity and ability to transmit different viruses. In 1996, 6 months after planting, CMD incidences were highest at sites 1 and 2, then decreased progressively until site 6, and remained low at sites 7 and 8. The largest B. tabaci populations also occurred at northernmost sites, 1–3. In 1997, CMD incidence increased significantly at sites 5–8 and this was associated with significant increases in the B. tabaci populations. The pandemic's spread was also associated with significant increases in the percentage of dual infections of East African cassava mosaic virus‐Uganda and African cassava mosaic virus, which caused the severest symptoms and the greatest reduction in leaf area. Whitefly adults collected from within the pandemic area were infective, whereas those collected ahead of the pandemic were not. The transmission rate of African cassava mosaic virus from plants with dual infections was significantly less than that of East African cassava mosaic virus‐Uganda, which may explain the latter's predominance within the pandemic. These results show that the arrival of East African cassava mosaic virus‐Uganda into areas affected previously only by African cassava mosaic virus, has resulted in novel virus/vector/host–plant interactions that drive the pandemic's continued spread.
Phylogenetic relationships of basal hexapods among the mandibulate arthropods: a cladistic analysis based on comparative morphological characters
Authors: Bitsch Colette , Bitsch Jacques
Published: November 2004

In this paper we propose a reappraisal of the relationships between the basal hexapod lineages (the former ‘apterygote’ insects) and the other major groups of mandibulate arthropods. It results from a cladistic analysis including 72 characters based on external morphology, internal anatomy and development. Detailed comments are provided on the various characters used and the scoring of their states. The 35 terminal taxa include 12 hexapods (9 of which are basal ‘apterygote’ representatives), 7 myriapods, 13 crustaceans, and 3 chelicerates taken as outgroups. The results of our analyses are discussed in detail for each of the taxonomic groupings, and compared with those recently obtained by other authors using different approaches based on morphological, palaeontological, developmental or molecular sequence data. Our results support the monophyly of the Mandibulata, Crustacea, Atelocerata (Tracheata) and Hexapoda, but the assemblage of Myriapoda appears poorly supported. A close relationship between Crustacea and Hexapoda, as hypothesized by several authors, is not found in any of our analyses. Within Hexapoda, the Protura and the Collembola appear as independent clades, whereas the two unresolved dipluran taxa are grouped with the monophyletic Ectognatha (Archaeognatha, Zygentoma and Pterygota).
Cladistic revision of talitroidean amphipods (Crustacea, Gammaridea), with a proposal of a new classification
Authors: Serejo Cristiana S.
Published: November 2004

This paper reports the results of a cladistic analysis of the Talitroidea s.l., which includes about 400 species, in 96 genera distributed in 10 families. The analysis was performed using paup and was based on a character matrix of 34 terminal taxa and 43 morphological characters. Four most parsimonious trees were obtained with 175 steps (CI = 0.617, RI = 0.736). A strict consensus tree was calculated and the following general conclusions were reached. The superfamily Talitroidea is elevated herein as infraorder Talitrida, which is subdivided into three main branches: a small clade formed by Kuria and Micropythia (the Kurioidea), and two larger groups maintained as distinct superfamilies (Phliantoidea, including six families, and Talitroidea s.s., including four). Within the Talitroidea s.s., the following taxonomic changes are proposed: Hyalellidae and Najnidae are synonymized with Dogielinotidae, and treated as subfamilies; a new family rank is proposed for the Chiltoniinae.