bluuebunny/crossref_metadata_2025 huggingface dataset:
Cholera toxin (CTX) genetic element in Vibrio cholerae O139
Authors: Bhadra Rupak K. , Roychoudhury Susanta , Banerjee Rajat K. , Kar Sujata , Majumdar Ruma , Sengupta Sanghamitra , Chatterjee Soma , Khetawat Gopal , Das Jyotirmoy
Published: June 2009

PFGE analysis of the Notl-and Sfil-digested genome of Vibrio cholerae O139 strains isolated from different epidemic regions of India showed that all the strains are of clonal origin and the genome size is about 2·2 Mb. An analysis of the electrophoretic profiles of the genome of O139 strains, the RFLP of the cholera toxin (ctx) gene and Southern blot hybridization of Notl-digested genomes of classical, El Tor and 0139 with a Notl-linking clone of classical strain 569B, suggest that these strains closely resemble V. cholerae 01 biotype El Tor, but are widely different from the classical 01 vibrios. Using restriction enzymes which cleave a single site in either the core region or in the direct repeat sequence (RS) of the CTX genetic element, it has been shown that the genome of most of the O139 strains has two copies of the ctx gene in tandem connected by two RSs. The chromosomal location of the CTX genetic element in the 0139 strain is the same as that reported for El Tor vibrios. The organization of the virulence gene cassettes in different O139 strains shows genetic heterogeneity in the population. Whilst most of the epidemic strains have two copies of the CTX genetic element, in some strains the number of elements has been amplified and in at least one strain a single copy of the element has been deleted.
Multiple phase variation in haemolytic, adhesive and antigenic properties of Streptococcus gordonii
Authors: Jones G. W. , Clewell D. B. , Charles L. G. , Vickerman M. M.
Published: June 2009

Streptococcus gordonii gave rise to β-haemolytic variants (Bhp+ for beta-haemolysin production) at frequencies of 10-4-10-3 on agar medium containing washed horse erythrocytes. Bhp+ variants reverted to the wild-type α-haemolytic phenotype (Bhp-) at the same frequencies. There was a significant probability (> 0.1) that phase variation in Bhp and phase variation in the previously described Spp (sucrose promoted phenotype) would occur concomitantly, but there was no correlation between these phenotypes. There was evidence also of independent phase variation in adhesion to saliva-coated hydroxyapatite (Asp for adhesion to salivary pellicles), in lactose-sensitive coaggregation (Cls for coaggregation, lactose-sensitive) and in the concentrations of particular cell surface antigens (Cap for cell antigen profile) in strains that had undergone phase changes in Spp and/or Bhp. Phase variation in all these phenotypes were transitions between high and low levels of activity and each appeared to occur as an independent event. Significant associations (P ⩽ 0.0001 by contingency table analysis) between particular phenotypes such as Bhp and Asp and between Asp, Cls and Cap phenotypes, however, were apparent. The results suggest that S. gordonil cells become predisposed to phase variation and that the resulting independent phenotypic changes may give rise to phenotypically diverse streptococcal populations able to accommodate rapid and transient environmental changes in the mouth.
A gene replacement strategy for engineering nisin
Authors: Dodd Helen M. , Horn Nikki , Giffard Catriona J. , Gasson Michael J.
Published: June 2009

A lactococcal expression system was developed which allows the exclusive production of novel nisins encoded by mutated pre-nisin (nisA) genes. This system is based on a combination of a specifically constructed host strain and vectors which facilitate the genetic manipulation of the nisA gene. The wild-type chromosomal gene is effectively replaced with a variant nisA gene, by the technique of gene replacement. The recovery of full nisin immunity was employed as a means of directly selecting strains that had acquired an intact nisA gene by the gene replacement process. With this approach the other genes required for pre-nisin maturation are not affected and any alterations to DNA sequences are restricted to only those specific mutations introduced in the nisA gene. The effectiveness of the system was demonstrated by the expression of a number of variant nisA genes leading to the successful production and characterization of nisins containing the substitutions Dha5A, Dha33A, Dha5,33A, H27K, I30W and K12L. The enhanced yields of these engineered nisin molecules, when compared to their production in a plasmid-complementation system, underlines the improvement offered by this gene replacement strategy.
A gene cloning system for ‘Streptomyces toyocaensis’
Authors: Matsushima Patti , Baltz Richard H.
Published: June 2009

Summary: We explored different methods of introducing DNA into ‘Streptomyces toyocaensis’ and Streptomyces virginiae to construct stable recombinant strains. Plasmid pIJ702 isolated from Streptomyces lividans transformed protoplasts of ‘S. toyocaensis’ at a frequency of 7×103 transformants (μgDNA)-1. pIJ702 prepared from ‘S. toyocaensis’ transformed ‘S. toyocaensis’ protoplasts at a frequency of 1.5×105 (μgDNA)-1. suggesting that ‘S. toyocaensis’ expresses restriction and modification. Plasmid pRHB126 was transduced by bacteriophage FP43 into ‘S. toyocaensis’ at a frequency of 1.2×10−6 (p.f.u.)−1. Plasmids pOJ436 and pRHB304 were introduced into ‘S. toyocaensis’ by conjugation from Escherichia coli S17-1 at frequencies of about 2×10−4 and 1×10−4 per recipient, respectively. Analysis of several exconjugants indicated that pOJ436 and pRHB304 inserted into a unique øC31 attB site and that some of the insertions had minimal deleterious effects on glycopeptide A47934 production. The results indicate that ‘S. toyocaensis’ is a suitable host for gene cloning, whereas S. virginiae does not appear to be.
The gene cluster directing O-antigen biosynthesis in Yersinia enterocolitica serotype O:8: identification of the genes for mannose and galactose biosynthesis and the gene for the O-antigen polymerase
Authors: Zhang Lijuan , Toivanen Paavo , Skurnik Mikael
Published: June 2009

Summary: Therfbgene cluster ofYersinia enterocoliticaserotype O:8 (YeO8) strain 8081-c was cloned by cosmid cloning. Restriction mapping, deletion analysis and transposon mutagenesis showed that about 19 kb of the cloned DNA is essential for the synthesis and expression of the YeO8 O-side-chain inEscherichia coli.Deletion analysis generated a derivative that expressed semirough LPS, a phenotype typical of anrfcmutant lacking the O-antigen polymerase. The deletions and transcomplementation experiments allowed localization of therfcgene to the 3'-end of therfbgene cluster. The deduced YeO8 Rfc did not share significant amino acid sequence similarity with any other protein, but its amino acid composition and hydrophobicity profile are similar to those of identified Rfc proteins. In addition, the codon usage of therfcgene is similar to otherrfcgenes. Nucleotide sequence analysis identified three other genes upstream ofrfc.Two of the gene products showed 60-70% identity to the RfbM and RfbK proteins that are biosynthetic enzymes for the GDPmannose pathway of enterobacteria. The third gene product was about 50-80% identical to the bacterial GalE protein, UDPglucose 4-epimerase, which catalyses the epimerization of UDPglucose to UDPgalactose. Since mannose and galactose are both present in the YeO8 O-antigen repeat unit, the above three genes are likely to belong to therfbgene cluster. A gene similar to thegskgene downstream ofrfc,and genes similar toadkandhemHupstream of therfbgene cluster, were recognized. Thus therfbgene cluster of YeO8 is located between theadk-hemHandgskloci, and the order isadk-hemH-rfb-rfc-gskin the chromosome. Also in otherYersiniaspp., the locus downstream of thehemHgene is occupied by gene clusters associated with LPS biosynthesis.
Mapping of 61 genes on the refined physical map of the chromosome of Thermus thermophilus HB27 and comparison of genome organization with that of T. thermophilus HB8
Authors: Tabata Kazuyuki , Hoshino Takayuki
Published: June 2009

Summary: We have constructed refined physical maps of the chromosome (1.82 Mb) and the large plasmid pTT27 (250 kb) of Thermus thermophilus HB27. A total of 49 cleavage sites with five restriction enzymes, EcoRI, SspI, MunI, EcoRV and ClaI, were determined on the maps. The location of 61 genes was determined by using as probes 64 genes cloned from T. thermophilus or other Thermus strains. Comparison of the genomic organization of the chromosomes of T. thermophilus HB27 and HB8 revealed that they were basically identical, but some genes were located in different regions. Among 32 genes whose locations were determined on both the HB27 and the HB8 chromosomes, the copy number of rpsL-rpsG-fus-tufA, the locations of glyS, pol, and one copy of nusG-rplK-rplA were different. The IS1000 sequence was located only in one region on the HB27 chromosome. In contrast, IS1000 sequences were scattered over four regions on the chromosome of HB8. As each region in which glyS, pol, or one copy of nusG-rplK-rplA are present also contained IS1000 in HB8, it is suggested that IS1000 may play an important role in genomic rearrangements in Thermus strains.
Differentiation of human Capnocytophaga species by multilocus enzyme electrophoretic analysis and serotyping of immunoglobulin A1 proteases
Authors: Frandsen Ellen V. G. , Wade William G.
Published: June 2009

Summary: As part of a larger taxonomic investigation of the genus Capnocytophaga, 50 strains, including reference strains as well as clinical isolates, were subjected to multilocus enzyme electrophoretic (MLEE) analysis of 12 intracellular metabolic enzymes and characterization of their immunoglobulin A1 (IgA1) proteases by enzyme-neutralizing antibodies raised in rabbits. The dendrogram derived from cluster analysis of the MLEE data discriminated between the five known human Capnocytophaga species and separated the strains into two major divisions. Division A comprised C. gingivalis and C. granulosa strains, and division B comprised C. ochracea, C. sputigena and C. haemolytica strains. Immunoglobulin A1 (IgA1) protease activity, a known feature of C. ochracea, C. sputigena and C. gingivalis, was present in all strains except the type strain of C. haemolytica and two clinical isolates. Inhibition typing of IgA1 proteases of all active strains with enzyme-neutralizing antibodies against protease preparations of the type strains of C. ochracea, C. sputigena and C. gingivalis separated the strains into two major groups identical to the two divisions based on the MLEE data. Thus, the IgA1 proteases of C. granulosa and C. gingivalis seemed to be antigenically similar to one another, and different from the IgA1 proteases of C. ochracea and C. sputigena, which had similar characteristics. The clustering of the clinical isolates based on the MLEE analyses, which was confirmed by the antigenic characterization of IgA1 proteases, was in good agreement with the results of previous studies.
Candida Albicans has a Cell-Associated Ferric-Reductase Activity which is Regulated in Response to Levels of Iron and Copper
Authors: Morrissey Julie A. , Williams Peter H. , Cashmore Annette M.
Published: June 2009

For survival, pathogenic organisms such as Candida albicans must possess an efficient mechanism for acquiring iron in the iron-restricted environment of the human body. C. albicans can use iron from a variety of sources found within the host. However, it is not clear how biologically active ferrous iron is obtained from these sources. One strategy adopted by some organisms is to reduce iron extracellularly and then specifically transport the ferrous iron into the cell. We have shown that clinical isolates of C. albicans do have a cell-associated ferric-reductase activity. The determination of ferric-reductase activity of cells growing exponentially in either low- or high-iron media over a period of time indicated that C. albicans reductase activity is induced when in low-iron conditions. Moreover, we have demonstrated that C. albicans reductase activity is also regulated in response to the growth phase of the culture, with induction occurring upon exit from stationary phase and maximal levels being reached in early exponential stage irrespective of the iron content of the medium. These results suggest that C. albicans reductase activity is regulated in a very similar manner to the Saccharomyces cerevisiae ferric-reductase. Iron reduction and uptake in S. cerevisiae are closely connected to copper reduction, and possibly copper uptake. In this report we show that iron and copper reduction also appear to be linked in C. albicans. The ferric-reductase activity is negatively regulated by copper. Moreover, quantitative cupric-reductase assays indicated that C. albicans is capable of reducing copper and that this cupric-reductase activity is negatively regulated by both iron and copper. This is the first report that C. albicans has an iron- and copper-mediated ferric-reductase activity.
How do Highly Branched (Colonial) Mutants of Fusarium Graminearum A3/5 arise during Quorn® Myco-Protein Fermentations?
Authors: Wiebe Marilyn G. , Blakebrough Margaret L. , Craig Sally H. , Robson Geoffrey D. , Trinci Anthony P. J.
Published: June 2009

Chlorate-resistant, highly branched (colonial) mutants and auxotrophic mutants were used to study the nuclear distribution, morphology and growth of heterokaryons of the Quorn®myco-protein fungus,Fusarium graminearumA3/5. The results showed that for several complementary homokaryons, even a strong selective pressure was insufficient to maintain heterokaryons in a ‘balanced’ condition (i.e. exhibiting a wild-type or near wild-type phenotype). Furthermore, the margins of heterokaryotic colonies generally contained nuclei from only one of the parental homokaryons, indicating imperfect nuclear mixing within the mycelium. These observations suggest that recessive, colonial mutants may appear during Quorn®myco-protein production following shear-induced separation of hyphal fragments which contain a sufficiently high ratio of colonial : wild-type nuclei for the colonial phenotype to be expressed.
Inducer Expulsion and the Occurrence of an HPr(Ser-P)-Activated Sugar-Phosphate Phosphatase in Enterococcus Faecalis and Streptococcus Pyogenes
Authors: Ye Jing-Jing , Minarcik John , Saier Milton H.
Published: June 2009

Inducer expulsion, a phenomenon in which rapidly metabolizable sugars cause cytoplasmic dephosphorylation and efflux of pre-accumulated sugar-phosphates (sugar-P), has been documented for Streptococcus pyogenes, Streptococcus bovis, and Lactococcus lactis but not for other Gram-positive bacteria. Using intact cells and membrane vesicles, we show that Enterococcus faecalis exhibits both inducer exclusion and inducer expulsion, and that the latter phenomenon is dependent on the metabolite-activated ATP-dependent HPr(Ser) kinase that phosphorylates Ser-46 in HPr of the phosphotransferase system. A small, heat-stable, membrane-associated, HPr(Ser-P)-activated sugar-P phosphatase (Pase II), previously identified only in Lc. lactis, is shown to be present in extracts of Enterococcus faecalis and Streptococcus pyogenes but not in those of Staphylococcus aureus, Streptococcus mutans, Streptococcus salivarius or Bacillis subtilis, organisms that do not exhibit the inducer expulsion phenomenon. Further, Lactobacillus brevis an organism that exhibits inducer expulsion by a different mechanism, also apparently lacks Pase II. The results reveal that Pase II is present in those organisms that exhibit the coupled sugar-P hydrolysis/expulsion mechanism but not those that lack this mechanism. They provide correlative evidence that Pase II initiates inducer expulsion in species of enterococci, streptococci and lactococci.
Degradation of 2,4-dichlorophenoxyacetic acid by haloalkaliphilic bacteria
Authors: Maltseva Olga , McGowan Catherine , Fulthorpe Roberta , Oriel Patrick
Published: June 2009

Three 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacterial isolates were obtained from the highly saline and alkaline Alkali Lake site in southwestern Oregon contaminated with 2,4-D production wastes. While similar in most respects, the three isolates differed significantly in 2,4-D degradation rates, with the most active strain, 1-18, demonstrating an ability to degrade up to 3000 mg 2,4-D I-1 in 3 d. This strain was well adapted to the extreme environment from which it was isolated, growing optimally on 2,4-D at pH 8.4-9.4 and at sodium ion concentrations of 0.6-1.0 M. According to its optimum salt concentration and pH for growth, this isolate was a moderately halophilic, alkaliphilic bacterium. The 16S RNA gene sequence (303 nt) was identical for all three isolates and most closely resembled those of the moderately halophilic eubacteria of the family Halomonadaceae (91% identity). Biochemical and genetic examination revealed strain 1-18 utilizes the same 2,4-D degradation pathway as most of the 2,4-D-degrading bacteria from non-extreme environments. Hybridization data and comparison of the partial sequences of the tfdA gene from the Alkali Lake isolates with those of bacteria from non-extreme environments suggested a common genetic origin of the 2,4-D degradation pathway in the two groups of micro-organisms.
Actin-related proteins in Anabaena spp. and Escherichia coli
Authors: Guerrero-Barrera Alma L. , García-Cuéllar Claudia M. , Villalba José D. , Segura-Nieto Magdalena , Gómez-Lojero Carlos , Reyes Magda E. , Hernández José M. , Garcia Rosa M. , de la Garza Mireya
Published: June 2009

Actin has been described in all eukaryotic cells as the major microfilament cytoskeletal protein. Although prokaryotic cells do not have a cytoskeleton, proteins related to the latter have been found in different prokaryotic species. We have found prokaryotic actin-related proteins in the enterobacteriumEscherichia coliand in the cyanobacteriaAnabaena cylindricaandAnabaena variabilis. They were identified by the following criteria: (1) by cross-reaction with a fluorescent conjugated anti-actin (rat-brain) mAb by Western blot analysis (in total cellular extracts); (2) specific binding of acetone powder and soluble cellular extracts to DNase 1; and (3) specific binding of cells and total cellular extracts to phalloidin. InE. coli, specific binding of phalloidin labelled with rhodamine to cells was detected by spectrofluorometry. In total cellular extracts, three bands of 60, 43 and 35 kDa were weakly recognized by the mAb by Western blot analysis; this recognition increased when phalloidin was added to the extracts. Furthermore, three polypeptides of 60 kDa were isolated by binding to DNase I, showing pl values of 6.7, 6.65 and 6.6, less acidic than all reported actin pl values. InA. cylindricaandA. variabilis, specific binding of phalloidin labelled with rhodamine to cells was also detected by spectrofluorometry. In total and soluble cellular extracts, the mAb recognized two bands of 45 and 40 kDa by Western blot analysis, but only the first was purified by binding to DNase I, and it showed three isoforms of pl values 6.8, 6.5 and 6.4. These results suggest the presence, in prokaryotes, of proteins with similar biochemical characteristics to eukaryotic actin.
Cell density influences antibiotic biosynthesis in Streptomyces clavuligerus
Authors: Sánchez L. , Braña A. F.
Published: June 2009

Production of cephamycin C and clavulanic acid by Streptomyces clavuligerus took place during the exponential phase of growth in a defined medium. Both antibiotic biosynthetic pathways were activated shortly after spore germination, but the timing and kinetics of activation were affected by inoculum density. Rapid activation was favoured by high inoculum density or by growth in medium conditioned by previous incubation of S. clavuligerus spores or mycelium. A heat-resistant conditioning factor able to accelerate the acquisition of antibiotic-biosynthetic capacity when added to low-density cultures was released in suspensions of spores in water. Conditioning factor was also obtained in suspensions of spores from different Streptomyces species or of Bacillus cells, indicating that the signal was not produced specifically by S. clavuligerus. Fractionation of conditioning factor showed that its effect was not due to a single molecule. The fractions contained amino acids (as free amino acids and oligopeptides) in amounts that roughly correlated with their respective conditioning power. Furthermore, the conditioning effect was reproduced by supplementing defined medium with amino acids and peptides in concentrations that mimicked those found in conditioning factor. When individually tested at concentrations in the micromolar range, only some amino acids were able to stimulate antibiotic biosynthetic capacity. This stimulation was also promoted by low concentrations (less than 1 μg ml-1) of peptide mixtures obtained with different proteolytic enzymes. The results suggest that both amino acids and peptides are responsible for the effects of conditioning factor released by spores. Possible implications of intercellular signalling on activation of secondary metabolism are discussed.
Complementary chromatic adaptation alters photosynthetic strategies in the cyanobacterium Calothrix
Authors: Campbell Douglas
Published: June 2009

The cyanobacterium Calothrix sp. strain PCC 7601 drastically changes phycobiliprotein composition and colour in response to light quality, through complementary chromatic adaptation (CCA). Red light promotes phycocyanin-II and inhibits phycoerythrin synthesis, while green light has the opposite effect, through changes in transcription regulated by a putative green/red photoreceptor(s). The effects of CCA on photosynthesis were characterized by measuring oxygen evolution and chlorophyll fluorescence parameters. Cells fully acclimated to either red or green light achieve a similar photosynthetic quantum yield of oxygen evolution (light-use efficiency). Shifting acclimated cells from green to red or from red to green light caused similar 40% drops in photosynthetic quantum yield. Therefore, full CCA significantly increases light use efficiency, which is of great importance under light-limited growth. Cells growing under red light are in state I, with very low PS II to PS I energy transfer, since red light is absorbed both by phycocyanin in the phycobilisome/PS II supracomplex and by PS I chlorophyll. Cells growing under green light are in state II, with high transfer of excitation energy from the phycobilisome/PS II supracomplex to PS I. This transfer allows green light captured by phycoerythrin to ultimately drive both PS I and PS II photochemistry.
An abundant hydrophobin (ABH1) forms hydrophobic rodlet layers in Agaricus bisporus fruiting bodies
Authors: Lugones Luis G. , Bosscher Jaap S. , Scholtmeyer Karin , de Vries Onno M. H. , Wessels Joseph G. H.
Published: June 2009

The SDS-insoluble protein fraction of Agaricus bisporus fruiting bodies was solubilized with trifluoroacetic acid. On SDS-PAGE this fraction was found to contain one abundant protein with an apparent M
r of 16 kDa. The N-terminal amino acid sequence of this protein was determined and RT-PCR used to isolate a cDNA clone which upon sequencing identified the protein as a typical class I hydrophobin (ABH1). The gene (ABH1) was isolated and sequenced, and a second hydrophobin gene (ABH2) was found about 2.5 kbp downstream of ABH1. Purified ABH1 self-assembled at hydrophobic-hydrophilic interfaces, producing the typical rodlet layer known from other hydrophobins. Similar rodlets were observed on the surface of the fruiting body, while immunological localization showed the hydrophobin to be particularly abundant at the outer surface of fruiting bodies, in the veil and in the core tissue of the stipe. Transcripts of ABH1 were found only in fruiting-body hyphae. The ABH1 hydrophobin is probably solely responsible for the hydrophobicity of the fruiting-body surface but may also line air channels within fruiting bodies.
A major T-cell-inducing cytosolic 23 kDa protein antigen of the vaccine candidate Mycobacterium habana is superoxide dismutase
Authors: Bisht Deepa , Mehrotra Jyoti , Dhindsa M. S. , Singh N. B. , Sinha Sudhir
Published: June 2009

This study describes the purification and immunochemical characterization of a major 23 kDa cytosolic protein antigen of the vaccine candidateMycobacterium habana(TMC 5135). The 23 kDa protein alone was salted out from the cytosol at an ammonium sulfate saturation of 80-95%. It represented about 1.5% of the total cytosolic protein, appeared glycosylated by staining with periodic acid/Schiff's reagent, and showed a pl of approximately 5.3. Its native molecular mass was determined as approximately 48 kDa, suggesting a homodimeric configuration. Immunoblotting with the WHO-IMMLEP/IMMTUB mAbs mc5041 and IT61 and activity staining after native PAGE established its identity as a mycobacterial superoxide dismutase (SOD) of the Fe/Mn type. The sequence of the 18 N-terminal amino acids, which also contained the binding site for mc5041, showed a close resemblance, not only with the reported deduced sequences ofMycobacterium lepraeandMycobacterium tuberculosisFe/MnSODs, but also with human MnSOD. In order to study its immunopathological relevance, the protein was subjected toin vivoandin vitroassays for T cell activation. It induced, in a dose-related manner, skin delayed hypersensitivity in guinea-pigs and lymphocyte proliferation in BALB/c mice primed withM. habana. Most significantly, it also induced lymphocyte proliferative responses, in a manner analogous toM. leprae, in human subjects comprising tuberculoid leprosy patients and healthy contacts.
Mechanisms regulating the transport of acetic acid in Saccharomyces cerevisiae
Authors: Casal Margarida , Cardoso Helena , Leao Cecilia
Published: June 2009

Cells of the yeast Sacchammyces cerevisiae IGC 4072 grown in medium with acetic acid produced a mediated transport system for acetic acid that behaved as an electroneutral proton symport for the anionic form of the acid. The system could transport propionate and formate but not lactate and pyruvate. Uptake of labelled lactic acid was negligible, no mediated transport system activity for this acid being found. The acetate transporter was also found in cells grown in lactic acid or ethanol media, suggesting that the carrier did not require the presence of an external inducer. When cells weregrown in lactic acid medium, uptake of labelled acetic acid, at pH 5.0, wasbiphasic and consistent with the presence of two distinct transport modes for the acid. One of these components corresponded to the acetatelproton symport, and the higher affinity system corresponded to a more general monocarboxylate carrier that could also transport lactate, pyruvate and propionate. Both systems were subject to repression by glucose, fructose, sucrose, maltose or galactose. In glucose-repressed cells, the undissociated form of the acids appeared to be the only one that could cross the plasma membrane, a diffusion mechanism being involved in the acid uptake. Under these growthconditions and when the extracellular pH was lower than that of the cytosol, accumulation of the acid could also be observed, it being a function of the pH.
Size and genomic location of the pMGA multigene family of Mycoplasma gallisepticum
Authors: Baseggio Nina , Glew Michelle D. , Markham Philip F. , Whithear Kevin G. , Browning Glenn F.
Published: June 2009

The pMGA multigene family encodes variant copies of the cell surface haemagglutinin of Mycoplasma gallisepticum. Quantitative Southern blotting, using an oligonucleotide probe complementary to a region conserved in the leader sequence of all known pMGA genes, was used to estimate the number of members of the family in the genome of seven strains of M. gallisepticum. The number of copies estimated to be present in the genome varied from 32 in strain F to 70 in strain R, indicating that the pMGA gene family may be second in size only to the tRNA family among prokaryotes. If all members of the pMGA family are of similar length to those which have been characterized, a minimum of 79 kb (7.7%) of the genome of strain S6, 82 kb (8.2%) of PG31 and 168 kb (16%) of the genome of strain R is dedicated to encoding variants of the same haemagglutinin. The GAA repeat motif identified in the intergenic region between all characterized pMGA genes appeared to be a feature common to most, if not all, pMGA genes, and furthermore probably exclusive to them. The genomic locations of members of the pMGA family were determined by PFGE and Southern blot hybridization of M. gallisepticum strain S6. The hybridizing regions were localized to four separate regions on the chromosome. The pMGA genes are likely to be predominantly arranged as tandem repeats within these regions, similar to the restricted regions for which the genomic sequence has been determined.
Utilization of transferrin and salmon serum as sources of iron by typical and atypical strains of Aeromonas salmonicida
Authors: Hirst Ian D. , Ellis Anthony E.
Published: June 2009

The ability of typical and atypical strains of Aeromonas salmonicida to utilize non-haem sources of protein-bound iron was evaluated. (i) In a plate bioassay, the suppression of growth imposed on typical and atypical A. salmonicida by addition of the high-affinity iron chelator ethylenediamine-di(o-hydroxyphenylacetic acid) (EDDA) to the growth medium was reversed by the addition of 30% or 90% iron-saturated bovine or human transferrin (Tf) or lactoferrin (Lf) to the growth medium. (ii) The mechanism of obtaining iron from Tf was investigated by the addition of bovine Tf contained within a dialysis bag. The reversal of iron-restricted growth suppression differed between the strains in that the atypical strains were unable to utilize Tf contained within a dialysis bag while the typical strains were able to do so. This suggested a siderophore-mediated uptake of iron from Tf by the typical strains, which are known to produce siderophores while atypical strains do not. (iii) A solid-phase binding assay using horseradish-peroxidase-conjugated or biotinylated Tf or Lf failed to detect Tf/Lf-binding activity using whole typical or atypical cells. (iv) When atypical extracellular products (ECP) plus bovine Tf or salmon serum were enclosed in a dialysis bag, diffusible products were released which could reverse the EDDA-imposed growth suppression of an atypical strain. This reversal was negated by inhibition of the ECP metalloprotease with EDTA. (v) Purified 70 kDa serine protease of a typical strain was able to digest bovine Tf to low molecular mass fragments as observed in SDS-PAGE. These results indicate that typical and atypical strains of A. salmonicida differ in their mechanism of utilization of non-haem protein-bound sources of iron. Typical strains utilize Tf via a siderophore-mediated mechanism and are also able to digest Tf with the extracellular serine protease. Atypical strains utilize Tf by a siderophore-independent mechanism probably involving the proteolytic degradation of Tf by the extracellular metalloprotease.
A putative cyclic peptide efflux pump encoded by the TOXA gene of the plant-pathogenic fungus Cochliobolus carbonum
Authors: Pitkin John W. , Panaccione Daniel G. , Walton Jonathan D.
Published: June 2009

Race 1 isolates of Cochliobolus carbonum are pathogenic on certain maize lines due to production of a host-selective cyclic tetrapeptide, HC-toxin. Flanking HTS1, which encodes the central enzyme in HC-toxin biosynthesis, a gene was identified and named TOXA. Like HTS1, TOXA occurred only in isolates of the fungus that make HC-toxin and was present as two linked copies in most toxin-producing isolates. HTS1 and TOXA were transcribed in the opposite orientation and their transcriptional start sites were 386 bp apart. The predicted product of TOXA was a 58 kDa hydrophobic protein with 10-13 membrane-spanning regions. The sequence was highly similar to several members of the major facilitator superfamily that confer resistance to tetracycline, methylenomycin, and other antibiotics. Although it was possible to mutate one copy or the other of TOXA by targeted gene disruption, numerous attempts to disrupt both copies in a single strain were unsuccessful, suggesting that TOXA is an essential gene in strains that synthesize HC-toxin. On the basis of its presence only in HC-toxin-producing strains, its proximity to HTS1 and its predicted amino acid sequence, we propose that TOXA encodes an HC-toxin efflux pump which contributes to self-protection against HC-toxin and/or the secretion of HC-toxin into the extracellular milieu.
Board Structure and Modified Audit Opinions: Evidence from the Portuguese Stock Exchange
Authors: Farinha Jorge , Viana Luis Filipe
Published: June 2009

Prior research has found evidence that some characteristics of the board of directors influence the quality of financial reporting. In this study we extend the literature by analysing a different dimension of financial reporting quality, the probability of a firm receiving a modified audit opinion. To this end, we considered a sample of companies listed on Euronext Lisbon where, unlike the current situation in other markets such as the US, firms can publish financial statements not in accordance with GAAP. Using 171 firm‐year observations for the period 2002–05, the evidence we report is consistent with the hypotheses that firms with more diligent and independent boards are less likely to receive a modified audit opinion. Results are robust to different specifications and also show that the existence of dividend payments, financial health, performance and growth opportunities are additional factors associated with the likelihood of a modified audit opinion. Our analysis also shows that the transition in 2005 to a reporting framework based on international accounting standards is strongly related with better financial reporting quality.
Dual‐task study of cognitive and postural interference: a preliminary investigation of the automatization deficit hypothesis of developmental co‐ordination disorder
Authors: Tsai C‐L. , Pan C‐Y. , Cherng R‐J. , Wu S‐K.
Published: June 2009

Background  The purpose of this study was to investigate whether children with developmental co‐ordination disorder and balance problem (DCD‐BP) had greater problems than controls in performing a primary balance task while concurrently completing different cognitive tasks varying in oral or listening cognitive complexity, as well as to investigate the automatization deficit hypothesis of DCD‐BP.

Methods  Children with DCD‐BP (n= 39), along with age‐matched control counterparts (n= 39), were placed on automatic processing situation under dual‐task conditions. All children were required to perform a primary task, five dual‐task paradigms (oral counting task, auditory–verbal reaction task, auditory–choice reaction task, auditory–memory task and articulation alone) and an eyes‐closed balancing task.

Results  In the primary task condition, the differences were not statistically significant (P= 0.393) between children with and without DCD‐BP. However, children with DCD‐BP were significantly more impaired on three of five dual‐task conditions (oral counting task: P= 0.003; auditory–verbal reaction task: P= 0.011; auditory–memory task: P= 0.041) compared with the single‐task situation, with the exception of the auditory–choice reaction task (P= 0.471) and articulation alone (P= 0.067).

Conclusions  These results suggest that children with DCD‐BP were more cognitively dependant and may have an automatization deficit.
Quality of life measurement in paediatric and adolescent populations with HIV: a review of the literature
Authors: Garvie P. A. , Lawford J. , Banet M. S. , West R. L.
Published: June 2009

Purpose  To review the quality and utility of currently available self‐report generic quality of life (QOL) and health‐related quality of life (HRQOL) measures for use with children and adolescents with human immunodeficiency virus and/or acquired immunodeficiency syndrome (HIV/AIDS).

Methods  Literature searches were conducted to identify QOL and HRQOL measures developed for, adapted for, or otherwise used with paediatric and adolescent populations with HIV/AIDS. The quality of measures (i.e. item generation techniques, instrument properties including reliability, validity and responsiveness) were compared and critically evaluated.

Results  Nineteen QOL/HRQOL measures were identified. Item content was generated from the respondent (adult) population in only eight (42%) measures. Seventeen (90%) measures reported internal reliability in the accepted range between 0.70 and 0.90 and four (21%) reported reproducibility statistics in this range. Although validity was reported for 19 (100%) measures, only six (32%) showed evidence for three or more properties, with construct validity being the most commonly reported aspect. The authors of eight (42%) measures reported evidence for responsiveness.

Conclusions  While almost all measures reviewed demonstrated adequate psychometric properties, only one‐third demonstrated all aspects of validity, and less than half demonstrated responsiveness. None included paediatric or adolescent populations with HIV/AIDS in their development, neglecting to obtain input from target respondents in item generation to determine what health‐related and daily functioning factors are of importance to them. Despite noted limitations, the AUQUEI or the SWED‐QUAL appear the best currently available generic measure, and the MQOL‐HIV the preferred disease‐specific measure, at least for use with older adolescents/young adults.
Lichen acclimatization on retention trees: a conservation physiology lesson
Authors: Jairus Kadi , Lõhmus Asko , Lõhmus Piret
Published: June 2009

1. Green‐tree retention (GTR) has been suggested as a means to effectively support epiphytic lichen species in managed forests, given the low lichen mortality on retention trees in the short term. However, a long‐term perspective requires a physiological understanding of lichen responses to logging. This study compares anatomical, morphological and physiological traits of lichens on retention trees and on intact forest trees.

2. Thalli of nine taxa (Buellia griseovirens,Cladonia digitata,Hypogymnia physodes,Lecanora allophana,Lecanora pulicaris,Leprariaspp.,Peltigera praetextata,Pertusaria amaraandPhlyctis argena) were sampled from birchBetulaspp. and aspenPopulus tremulain GTR cuts, where they had previously been reported to survive well, and in adjacent managed forests. In the laboratory, chlorophyll fluorescence parameterFv/Fm, thickness of the upper cortex, photobiont to mycobiont ratio and (inLecanoraspecies) the relative area of the apothecia were measured.

3. All the lichen samples collected from GTR cuts appeared alive, but theirFv/Fmwas significantly lower, relative areas of the apothecia were larger and the upper cortices of thalli were thicker compared with the samples from adjacent forests. No difference in photobiont to mycobiont ratio was found. These patterns were broadly consistent among species, indicating a common mechanism: while suffering from photoinhibition, the lichens had acclimatized to the open conditions and increased their investment to sexual reproduction in a few years.

4. Synthesis and applications. The study highlights the value of a morpho‐physiological framework for conservation management by pointing out that, in GTR areas, lichen survival is high‐irradiation limited and heavily dependent on phenotypic plasticity. A thin upper cortex may be a common feature of the most sensitive species. To sustain epiphyte populations in managed forests, precautionary harvesting strategies (gradual felling; group‐retention; extended rotations) should be preferred and large‐enough populations should be preserved, even though short‐term studies suggest a high survival of lichens in cut areas.
Nurses’ perceived facilitators and barriers to assessing for alcohol use in Taiwan
Authors: Tsai Yun‐Fang
Published: June 2009

Aims.  To explore nurses’ perceived facilitators and barriers to assessing for alcohol use in Taiwan.

Background.  Excessive alcohol use has been associated with health, social and legal problems. Helping health care providers to detect and treat hazardous or harmful drinkers is an important worldwide issue.

Design.  A cross‐sectional design was used.

Methods.  Nurse participants (n = 741) were recruited from 10 randomly selected hospitals in Taiwan. In these hospitals, nurses were selected from the Emergency Department, psychiatric and gastrointestinal medical–surgical units where most patients with alcohol problems are seen. Data were collected by facilitator and barrier scales as well as a background information form.

Results.  Nurses identified the top facilitator and barriers to assessing for alcohol use as ‘want to know if patients’ drinking problems are related to their illness’ and ‘patients’ purposefully conceal information’, respectively. Older nurses and those with longer general clinical experience had more perceived facilitators to assessing for alcohol use. Nurses’ perceived facilitator scores were significantly and positively related to their intention scores, whereas their perceived barrier scores were significantly and negatively related to their intention scores. In addition, scores for perceived facilitators and barriers differed significantly by nurses’ education level, work unit, experiences with assessing for alcohol use and previous attendance at training courses for assessing alcohol use.

Conclusions.  Our results suggest a need to strengthen nurses’ education and training on the assessment of alcohol use in Taiwan.

Relevance to clinical practice.  Education and training programmes should aim to enhance Taiwanese nurses’ alcohol knowledge, to emphasise the impact of alcohol use on illness and treatment and to enhance nurses’ perceived facilitators and decrease their perceived barriers to assessing for alcohol use.
Rheumatoid arthritis patient education: RA patients’ experience
Authors: Mäkeläinen Paula , Vehviläinen‐Julkunen Katri , Pietilä Anna‐Maija
Published: June 2009

Aim and objective.  The purpose of this paper is to describe the content of patient education as portrayed and evaluated by rheumatoid arthritis (RA) patients.

Background.  Rheumatology nurses have an important role in educating and supporting RA patients. However, there is a lack of knowledge of the RA patients’ own perspective of patient education.

Design.  Survey.

Method.  Data for this study were collected from 173 RA patients from 11 hospitals and 23 health centers using open‐ended questions. Fifty‐seven percent (57%) of the patients described the content of patient education and eighty‐one percent (81%) evaluated it expressing their experience and satisfaction with it. Data were analysed using descriptive and non‐parametric statistical tests.

Results.  Rheumatology nurses mostly gave their RA patients information about how to use the anti‐rheumatic drugs prescribed to them (26%). About half (51%) of the patients were satisfied with patient education. However, every fourth patient (24%) was not satisfied, the main reason for the dissatisfaction being that nurses did not focus on the patient’s emotional support. The patients of over 57 years of age and those who had suffered from RA for over five years were more satisfied with their education than the others.

Conclusions.  It is important that rheumatology nurses, besides passing on medical treatment‐related information, concentrate on RA patients’ emotional well‐being.

Relevance to clinical practice.  The results provide a useful insight into RA patient education. Nurses should avoid merely passing on information in a routine workmanlike way. It is important that they take time to discuss their patients’ feelings and worries especially with newly diagnosed patients. RA patient education should balance patients’ information needs with their need for emotional support.
Religion and the secularisation of health care
Authors: Paley John
Published: June 2009

Aims and objectives. To assess the claim that conceptualisations of religion and spirituality should be grounded in theology, and acknowledge the global resurgence of religion.

Background. Although there is widespread agreement in the nursing literature that ‘spirituality’ is a broader concept than ‘religion,’ and should be understood generically, this approximate consensus has occasionally been challenged. A recent paper by Barbara Pesut and colleagues argues that the generic view not only empties spirituality of powerful religious symbols and narratives, but underestimates the continuing social influence of religion, and its resurgence on a global scale. Accordingly, these authors suggest three principles for conceptualising spirituality and religion in health care, one of which is that conceptualisations should be grounded in philosophical and theological thinking, and should not ignore the global resurgence of religion.

Method. Critical review.

Conclusion. The Pesut principle privileges theology, disregarding other disciplines which theorise religion. Arguably, it privileges specifically Christian theology, the history of which suggests a politics of orthodoxy and an epistemology of authority and obedience. The global resurgence of religion is not, in fact, global, as the industrialised countries have experienced a marked shift towards secular‐rational values; and the postindustrial phase of development is associated with self‐expression values, which represent a challenge not merely to religious institutions (arguably an affirmation of ‘spirituality’) but to traditional elites and structures of all kinds. Finally, religion ‘resurgent’ is not an attractive model for health care, since many of its most obvious manifestations are incompatible with the ideology of health professionals.

Relevance to clinical practice. In the secular societies of Europe, if not North America, there should be no expectation that nurses provide spiritual care. It is a requirement of the great separation between civil order and religion that the health services, as a public space, should remain thoroughly secular.
Daily observation of cognitive functioning in hospitalised patients on acute geriatric wards
Authors: Persoon Anke , Banningh Liesbeth Joosten‐Weyn , Van De Vrie Wim , Olde Rikkert Marcel G M , Van Achterberg Theo
Published: June 2009

Background.  Daily observation by nurses of the cognitive function of patients is of high ecological validity because cognitive functioning is observed in a natural setting around the clock.

Aim.  To evaluate why and how geriatric nurses observe the cognitive functioning of their patients.

Design.  Survey.

Methods.  A self‐developed questionnaire was administered to a purposeful sample of nurses working on geriatric wards of seven acute care hospitals. The questions were open‐ended. Data were analysed through content analysis.

Results.  The questionnaire was completed by 97 nurses (response rate 77%). Categorisation of the many objectives reported by the nurses revealed four themes: to tailor nursing interventions (51%), to determine discharge arrangements (46%), to support medical diagnosis and therapy (43%) and to map specific elements of functional capacity (34%). Nurses reported also many different domains to observe (mode 2; range 0–7), only 73% of which were actual cognitive domains. The most commonly mentioned cognitive domain was psychomotor behaviour (63%), followed by executive functions (48%), language (37%), attention (33%), thinking (25%) and consciousness (20%).

Conclusions.  Geriatric nurses not only made daily observations of their patients’ cognitive functioning to support medical diagnoses, but also to guide nursing interventions and determine discharge arrangements. The assessment domains varied fairly widely, because the participants’ understanding of the concept cognitive functioning was vague, incomplete and often incorrect.

Relevance to clinical practice.  This is the first study that investigated why geriatric nurses make daily observations of their patients’ cognitive functioning. In addition, we explored their understanding of the concept of cognitive functioning. Based on the fact that the content of an assessment is determined by its aim, the objectives to perform daily observations have to be clear and stated explicitly. To observe patients in an unambiguous way, it will be necessarrily to develop a validated observation scale.