bluuebunny/crossref_metadata_2025 huggingface dataset:
Action research and quality of care: a mechanism for agreeing basic values as a precursor to change*
Authors: Nolan Mike , Grant Gordon
Published: July 2003

This paper describes the trend apparent in nursing and other practice disciplines towards more participative and collaborative methods of enquiry as exemplified by action research. In so doing it notes the conceptual similarities between action research, change theory and quality initiatives. Particular attention is focused on the need to establish the basic values which provide the impetus and direction for subsequent activity. The difficulties this may pose are illustrated by reference to the application in two continuing care hospital wards for elderly patients of a checklist operationalizing a typology of care. A mechanism to facilitate and make explicit the values underpinning care in any given environment is suggested.
How to make the right choice: a new model for the selection interview
Authors: Taylor Catherine
Published: July 2003

The problems encountered when selecting new members of staff in the higher education setting are those universal in any type of organization. Nursing faculties, however, have an even greater difficulty in selecting appropriate staff owing to the diversity of both clinical and academic backgrounds of applicants. The organization is therefore stimulated and challenged in its ability to select the right employee for the job. The literature tends to support the use of group decision making in selection and the function of the group in the interview setting is to evaluate the applicant's prior learning against desirable characteristics. From an analysis of the literature, criteria relating to desirable employee characteristics for nurse academics have been developed. The author has identified a new model to use in assisting the selection panel in predicting the right person for the job.
An assessment of the value of health education in the prevention of childhood asthma
Authors: Deaves Doreen M
Published: July 2003

A research project, which looks at the value of health education in the prevention of childhood asthma, is described The project was a controlled trial by a health visitor focused within the community This exploratory research looked at three groups of children over a 2‐year period, and compared the effect of (a) individual health education, and (b) group health education During the first year, two groups were active, one receiving individual health education, the other collecting data of the same type During the second year, a third group was involved in health education sessions The findings have been similar in both cases, in that both groups have demonstrated a good improvement in knowledge of asthma and its treatment Through the active involvement of using a peakflow meter and diary records in the health education programme, both groups receiving health education have shown a significant improvement in the morbidity indicators related to night symptoms and restricted activities The qualitative analysis of the research also highlighted the value parents of asthmatic children place on counselling
Suggested community psychiatric nursing interventions with clients suffering from anorexia nervosa and bulimia nervosa
Authors: Meades Stephen
Published: July 2003

Clients suffering from the fasting and gorging syndromes of anorexia and bulimia nervosa are at significant risk of self‐harm even if treated with apparent success in hospital Two major issues (not inevitably co‐existing) appear to be at work in these illnesses, distorted perception by the sufferer of his or her own body appearance and stressful interpersonal relationships originating in one of a variety of groups of which the sufferer is a member (Fear of psychosexual maturity, that is, the clients’ inability to develop an age‐appropriate sexual identity, is treated in this paper as being the product of faulty interactional patterns, it is also a less clear‐cut issue in bulimia nervosa than in anorexia) A supervised hospital in‐patient treatment regime concentrating upon weight gain, effective discouragement of purgation and vomiting, possible drug treatment and perhaps dual or independent usage of individual or group psychotherapy with focused cognitive–behavioural task‐oriented approaches, will not realize effective change unless these issues are resolved Community psychiatric nurses (CPNs) are well‐placed to observe and supervise people with eating disorders who are potentially vulnerable to relapse following discharge from hospital Strategies for effective CPN interventions in the community care of anorectic and bulimic clients are suggested in the paper
The significance of a sense of coherence for subjective health in persons with insulin‐dependent diabetes
Authors: Lundman Berit , Norberg Astrid
Published: July 2003

The strength of an insulin‐dependent, diabetic (IDDM) person's sense of coherence (SOC), conceptualized according to Antonovsky's salutogenetic model, was related to patterns of problem‐solving and to emotional coping strategies These personal SOC scores were also related to reported positive experiences, problems in daily life, problems in relation to the environment, worries about long‐term complications, tedium and well‐being which had been measured 5 years earlier In the entire IDDM group the mean score for the SOC was 143 There was a significant correlation between the SOC scores and coping patterns (Z – 2053, P<0 04) The subgroup labelled ‘experts’ had the highest SOC scores There were also significant correlations between the SOC scores and problems in relation to the environment (r– 0 08, P 0 03), tedium (r– 0 69 P 0 01) and well‐being (r– 0 64, P 0 02) There were no correlations between the SOC scores and metabolic control, reported experiences that the disease had positively influenced the diabetic person's life, problems in daily life, or worries about long‐term complications It was concluded that a sense of coherence seems an important factor which contributes to successful emotional coping with the demands of the disease As subjective health is an important nursing goal the salutogenic model appears to have potential utility in the care for the person with IDDM
Intuition as a function of the expert nurse: a critique of Benner's novice to expert model
Authors: English Ian
Published: July 2003

Benner's model of skill acquisition is currently receiving considerable interest from nurse educationalists, and promises to form the basis for some curricula offered by colleagues of nurse education This paper debates the ‘novice to expert’ model and seeks to explain exactly what an ‘expert’ is The Benner model proposes that one component of expertise is workmg from an intuitive base This claim is disputed and the definition of intuition is contested Alternative explanations to account for the intuitive responses of Bermer's subjects are suggested.
Measuring the impact of nursing interventions in the community: a selective review of the literature
Authors: Barnball K Louise , Mackenzie Ann
Published: July 2003

In a resource conscious environment, it is imperative that nurses use their skills and knowledge to provide an optimum service It is suggested that nurses working in the community must measure the impact of their nursing interventions to guide their own role development and to inform the purchasing process This literature review has revealed, however, that little progress has been made in this area by nurses within the community setting Indeed, it is suggested that research is needed to test reliable and valid methods of outcome measurement
Exploring consumer views of care provided by the Macmillan nurse using the critical incident technique
Authors: Cox Karen , Bergen Ann , Norman Ian J
Published: July 2003

This study focuses on descriptive accounts of one Macmillan nurse's work, as provided by key individuals coming into contact with this specialist professional service Twenty respondents (eight patients, five carers, five district nurses and two general practitioners) were interviewed using a variation of the critical incident technique Data were analysed in terms of meaningful observed events (critical happenings) that were perceived as effective or ineffective with respect to the delivery of high‐quality nursing care Some variations were found between groups of respondents in their perception of the nurse's role However, there was a general emphasis on the possession of specialist knowledge of terminal cancer care and the positive impact of interventions to both the patient and to lay and professional carers The critical incident technique was found to be a valuable method for eliciting detailed accounts of the work of the nurse in this specialized field of practice
Evaluation of the pain response by Mexican American and Anglo American women and their nurses
Authors: Calvillo Evelyn Ruiz , Flaskerud Jacquelyn H
Published: July 2003

This study examined the relationship between ethnicity and pain The study addressed three major research questions The first question asked whether there was a significant difference in Mexican American women's and Anglo American women's response to cholecystectomy pain Secondly, the nurses’ attribution of pain to each of the two ethnic groups was compared Finally, the patient's evaluation of the pain being experienced was compared to the nurse's evaluation of the pain the patient was experiencing The sample consisted of 60 patient subjects and 60 nurse responses Data were collected at two major teaching hospitals in southern California Patient pain was measured using the McGill Pain Questionnaire, amount of analgesics and three physiological measures The nurse's assessment of patient pain was measured using the Present Pain Intensity scale MANOVA was used to analyse differences between the two ethnic groups on all measures of pain and no significant differences were found between the two ethnic groups on any of the measures of pain However, nurses judged the two ethnic groups’ pain response differently, assigning more pain to Anglo Americans Finally, a dependent t‐test was used to compare nurses’ and patients’ evaluation of pain There were significant differences Nurses evaluated the patients’ pain as being less than patients did Pearson product‐moment correlations were used to examine the relationship between pain and sample characteristics of both patients and nurses For the nurses, pain was significantly related to the patient's education, place of birth, language and religion
Clinical role activities of nurse teachers in Project 2000 programmes
Authors: Crotty Margaret
Published: July 2003

This paper presents the findings related to the clinical role activities of nurse teachers in Project 2000 programmes Data were collected by a Delphi survey of 25 colleges of nursing that had implemented Project 2000 between September 1989 and April 1991 The findings from the Delphi survey were explored more fully through in‐depth interviews with a sample of the respondents The findings identified a very strong commitment of the respondents to a clinical liaison role But they did not perceive their role to be one of teaching students through ‘hands on care', they felt this was the role of the qualified staff in the clinical areas The respondents considered it important to maintain their clinical credibility through theoretical updating rather than being able to perform as an expert practitioner
Nursing education in the private sector
Authors: Orr John G
Published: July 2003

With perhaps some minor variations, it can be claimed that colleges/schools of nursing have viewed their raison d'etre as providing education for pre‐registration students of nursing The particular philosophy of the college would determine whether or not in‐service education and post basic courses figured highly as educational priorities Whether pre‐ or post‐registration, colleges have been their remit almost entirely within statutory frameworks With the advent of Project 2000 many schools/colleges amalgamated in order to provide multiple branches of nurse education However, anticipated numbers of entrants to nursing have not always materialized and we are now led to believe that revised staffing ratios will result in decreasing numbers of qualified nursing staff Faced with decreased numbers of recruits to nursing, colleges of nursing can undergo even larger amalgamations or look elsewhere for some of their business While nurse education should always be the central focus of colleges of nursing, the time has now come when we must sell our wares in a much wider marketplace Consideration should be given to mounting multi‐disciplinary courses within the health professions and to providing skills to other professions Short courses, for instance on child abuse, could be provided for teachers in primary and secondary education While recognizing a vast range of potential customers, this paper confines itself to education within the private sector
Application of Moos and Schaefer's (1986) model to nursing care of elderly persons relocating to a nursing home
Authors: Oleson Marjone , Shadick Kathleen McGlynn
Published: July 2003

Elderly persons relocating to a nursing home experience a life transition that they usually perceive as a crisis Effective coping with this transition/crisis requires effective management of the event Nurses caring for these persons are challenged to assess and intervene to assist them to achieve positive outcomes from this transition Moos & Schaefer's (1986) Conceptual Model for Understanding Life Crises and Transitions depicts a process by which nurses may help elderly persons cope effectively with relocation to a nursing home This paper describes the model and its application to the nursing care of elderly persons relocating to a nursing home, including a case study The extent to which the model has been empirically tested with populations in long‐term care settings is critically analysed
Mobility: a concept analysis
Authors: Rush Kathy L , Ouellet Louiselle L
Published: July 2003

In this paper, the authors present their analysis of the concept of mobility as a starting point for the development of relevant theory Multiple uses of the concept are considered and provisional criteria identified Case examples, together with antecedents and consequences, of the concept are presented Finally, research questions that would form the basis of fieldwork have been generated
Expression and regulation of the crucial plant‐like ferredoxin of cyanobacteria
Authors: Mazouni Khalil , Domain Francis , Chauvat Franck , Cassier‐Chauvat Corinne
Published: July 2003

The Synechocystis fedI gene (petF, ssl0020) was found to be strongly expressed under the negative control of H2O2 or heavy metals, and the positive control of light fluence (regulation dependent on active photosynthesis) or carbon availability [under the control of NdhR, the regulator of the ndh3 operon encoding NAD(P)H dehydrogenase subunits]. The basic and constitutive promoter (BP) of fedI extending from −62 to +25 (relative to the transcription start point) is weakly active, presumably because it harbours a long (30 bp) spacer between the two crucial motifs: the −10 box (5′‐TAgtAT‐3′, −13 to −8) and the ‘−35’ box (5′‐TTGctA‐3′, −49 to −44). BP strength is strongly enhanced by the two upstream regions, −113 to −82 and −151 to −114, mediating the 30‐fold constitutive stimulation and the fourfold light activation respectively. Three well‐conserved transcriptional elements were characterized for the first time, namely the −19 box (5′‐TTTT‐3′) that is essential to transcription, and the two twice repeated elements that are both critical to light induction: the TTGyCA‐3′ box (−35 to −30, and −125 to −120) and the 5′‐ATTTyA‐3′ box (−55 to −50, and −134 to −129). That two of these light induction motifs (5′‐TTGtCA‐3′, −35 to −30; 5′‐ATTTcA‐3′, −55 to −50) occur in the constitutive BP promoter indicate that in the fedI gene light activation and transcription per se are closely interacting. Interestingly, the fedI gene from marine strains was found to lack the three transcriptional elements presently described, as well as the 5′‐AGGA‐3′ Shine–Dalgarno sequence, which are all conserved among the fedI from non‐marine strains.
Microcin E492 antibacterial activity: evidence for a TonB‐dependent inner membrane permeabilization on Escherichia coli
Authors: Destoumieux‐Garzón Delphine , Thomas Xavier , Santamaria Mónica , Goulard Christophe , Barthélémy Michel , Boscher Bénédicte , Bessin Yannick , Molle Gérard , Pons Anne‐Marie , Letellier Lucienne , Peduzzi Jean , Rebuffat Sylvie
Published: July 2003

The mechanism of action of microcin E492 (MccE492) was investigated for the first time in live bacteria. MccE492 was expressed and purified to homogeneity through an optimized large‐scale procedure. Highly purified MccE492 showed potent antibacterial activity at minimal inhibitory concentrations in the range of 0.02–1.2 µM. The microcin bactericidal spectrum of activity was found to be restricted to Enterobacteriaceae and specifically directed against Escherichia and Salmonella species. Isogenic bacteria that possessed mutations in membrane proteins, particularly of the TonB–ExbB–ExbD complex, were assayed. The microcin bactericidal activity was shown to be TonB‐ and energy‐dependent, supporting the hypothesis that the mechanism of action is receptor mediated. In addition, MccE492 depolarized and permeabilized the E. coli cytoplasmic membrane. The membrane depolarization was TonB dependent. From this study, we propose that MccE492 is recognized by iron‐siderophore receptors, including FepA, which promote its import across the outer membrane via a TonB‐ and energy‐dependent pathway. MccE492 then inserts into the inner membrane, whereupon the potential becomes destabilized by pore formation. Because cytoplasmic membrane permeabilization of MccE492 occurs beneath the threshold of the bactericidal concentration and does not result in cell lysis, the cytoplasmic membrane is not hypothesized to be the sole target of MccE492.
The pair of arginine codons AGA AGG close to the initiation codon of the lambda int gene inhibits cell growth and protein synthesis by accumulating peptidyl‐tRNAArg4
Authors: Olivares‐Trejo José J. , Bueno‐Martínez José G. , Guarneros Gabriel , Hernández‐Sánchez Javier
Published: July 2003

To analyse the mechanism by which rare codons near the initiation codon inhibit cell growth and protein synthesis, we used the bacteriophage lambda int gene or early codon substitution derivatives. The lambda int gene has a high frequency of rare ATA, AGA and AGG codons; two of them (AGA AGG) located at positions 3 and 4 of the int open reading frame (ORF). Escherichia coli pth (rap) cells, which are defective in peptidyl‐tRNA hydrolase (Pth) activity, are more susceptible to the inhibitory effects of int expression as compared with wild‐type cells. Cell growth and Int protein synthesis were enhanced by overexpression of Pth and tRNAArg4 cognate to AGG and AGA but not of tRNAIle2a specific for ATA. The increase of Int protein synthesis also takes place when the rare arginine codons AGA and AGG at positions 3 and 4 are changed to common arginine CGT or lysine AAA codons but not to rare isoleucine ATA codons. In addition, overexpression of int in Pth defective cells provokes accumulation of peptidyl‐tRNAArg4 in the soluble fraction. Therefore, cell growth and Int synthesis inhibition may be due to ribosome stalling and premature release of peptidyl‐tRNAArg4 from the ribosome at the rare arginine codons of the first tandem, which leads to cell starvation for the specific tRNA.
Phosphatidylethanolamine and phosphatidylglycerol are segregated into different domains in bacterial membrane. A study with pyrene‐labelled phospholipids
Authors: Vanounou Sharon , Parola Abraham H. , Fishov Itzhak
Published: July 2003

To detect and characterize membrane domains that have been proposed to exist in bacteria, two kinds of pyrene‐labelled phospholipids, 2‐pyrene‐decanoyl‐phosphatidylethanolamine (PY‐PE) and 2‐pyrene‐decanoyl‐phosphatidylglycerol (PY‐PG) were inserted into Escherichia coli or Bacillus subtilis membrane. The excimerization rate coefficient, calculated from the excimer‐to‐monomer ratio dependencies on the probe concentration, was two times higher for PY‐PE than for PY‐PG at 37°C. This was ascribed to different local concentrations rather than to differences in mobility. The extent of mixing between the two fluorescent phospholipids, estimated by formation of their heteroexcimer, was found very low both in E. coli and B. subtilis, in contrast to model membranes. In addition, these two pyrene derivatives exhibited different temperature phase transitions and different detergent extractability, indicating that the surroundings of these phospholipids in bacterial membrane differ in organization and order. Inhibition of protein synthesis, leading to condensation of nucleoid and presumably to dissipation of membrane domains, indeed resulted in increased formation of heteroexcimers, broadening of phase transitions and equal detergent extractability of both probes. It is proposed that in bacterial membranes these phospholipids are segregated into distinct domains that differ in composition, proteo–lipid interaction and degree of order; the proteo‐lipid domain being enriched by PE.
The Aspergillus nidulans metR gene encodes a bZIP protein which activates transcription of sulphur metabolism genes
Authors: Natorff Renata , Sieńko Marzena , Brzywczy Jerzy , Paszewski Andrzej
Published: July 2003

The identification, isolation and characterization of a new Aspergillus nidulans positive‐acting gene metR, which encodes a transcriptional activator of sulphur metabolism, is reported. metR mutants are tight auxotrophs requiring methionine or homocysteine for growth. Mutations in the metR gene are epistatic to mutations in the negative‐acting sulphur regulatory scon genes. The metR coding sequence is interrupted by a single intron of 492 bp which is unusually long for fungi. Aspergillus nidulans METR is a member of bZIP family of DNA‐binding proteins. The bZIP domains of METR and the Neurospora crassa CYS3 transcriptional activator of sulphur genes are highly similar. Although Neurospora cys‐3 gene does not substitute for the metR function, a chimeric metR gene with a cys‐3 bZIP domain is able to transform the ΔmetR mutant to methionine prototrophy. This indicates that METR recognizes the same regulatory sequence as CYS3. The metR gene is not essential, as deletion mutants are viable and have similar phenotype as point mutants. In contrast to the Neurospora cys‐3, transcription of the metR gene was found to be regulated neither by METR protein nor by sulphur source. Transcription of metR gene is derepressed in the sconB2 mutant. Transcription of genes encoding sulphate permease, homocysteine synthase, cysteine synthase, ATP‐sulphurylase, and sulphur controller –sconB is strongly regulated by the metR gene product and depends on the character of the metR mutation and sulphur supplementation.
Biphasic intracellular expression of Staphylococcus aureus virulence factors and evidence for Agr‐mediated diffusion sensing
Authors: Shompole Sankale , Henon Kim T. , Liou Linda E. , Dziewanowska Katarzyna , Bohach Gregory A. , Bayles Kenneth W.
Published: July 2003

Staphylococcus aureus invades a variety of mammalian cells and escapes from the endosome to multiply in the cytoplasm. We had previously hypothesized that the molecular events leading to escape of S. aureus from the endosome involved the Agr virulence factor regulatory system. In this report we demonstrate that temporal changes in intracellular activation of the Agr regulon correlates with expression of membrane active toxins. Also, the initial expression of Agr by even small numbers of staphylococci resulted in the permeabilization of the endosomal membrane and the eventual escape of bacteria into the cytoplasm by 3 h post invasion. After Agr downregulation, a second peak of expression coincided with increased permeability of the host cell membrane. In contrast to the parental strain, an Agr‐mutant was unable to escape into the cytoplasm and was observed in intact endosomes as late as 5 h post invasion. These data provide evidence that staphylococcal virulence factor production during invasion of host cells is mediated by an Agr‐dependent process that is most accurately described in the context of diffusion sensing.
Distant cis‐active sequences and sialic acid control the expression of fimB in Escherichia coli K‐12
Authors: El‐Labany Sammia , Sohanpal Baljinder K. , Lahooti Maryam , Akerman Robert , Blomfield Ian C.
Published: July 2003

The phase variation of type 1 fimbriation in Escherichia coli is controlled by the inversion of a 314 bp element of DNA, determined by FimB (switching in both directions) or FimE (switching from the ON‐to‐OFF orientation predominantly), and influenced by auxiliary factors IHF, Lrp and H‐NS. The fimB gene is separated from the divergently transcribed yjhATS operon by a large (1.4 kbp) intergenic region of unknown function. Here, we show that fimB expression is regulated by multiple cis‐active sequences that lie far upstream (>600 bp) of the transcription start sites for the recombinase gene. Two regions characterized further (regions 1 and 2) show sequence identity, and each coincides with a methylation‐protected Dam (5′‐GATC) site. Regions 1 and 2 apparently control fimB expression by an antirepression mechanism that involves additional sequences proximal to yjhA. Region 1 encompasses a 27 bp DNA sequence conserved upstream of genes known (nanAT ) or suspected (yjhBC) to be involved in sialic acid metabolism, and we show that FimB expression and recombination are suppressed by N‐acetylneuraminic acid. We propose that E. coli recognizes the amino sugars as a harbinger of potential host defence activation, and suppresses the expression of type 1 fimbriae in response.
Coxiella burnetii express type IV secretion system proteins that function similarly to components of the Legionella pneumophila Dot/Icm system
Authors: Zamboni Dario S. , McGrath Susan , Rabinovitch Michel , Roy Craig R.
Published: July 2003

Coxiella burnetii is an obligate intracellular pathogen that replicates in large endocytic vacuoles. Genomic sequence data indicate that 21 genes encoding products that are similar to components of the Legionella pneumophila Dot/Icm type IV secretion system are located on a contiguous 35 kb region of the Coxiella chromosome. It was found that several dot/icm genes were expressed by Coxiella during host cell infection and that dot/icm gene expression preceded the formation of large replicative vacuoles. To determine whether these genes encode a functional type IV secretion system, we have amplified the Coxiella dotB, icmQ, icmS and icmW genes and produced the encoded proteins in Legionella mutants in which the native copy of each gene had been deleted. The Coxiella dotB, icmS and icmW products restored dot/icm‐dependent growth of Legionella mutants in eukaryotic host cells. The Coxiella IcmQ protein and the Legionella IcmR protein did not interact, which could explain why the Coxiella icmQ gene was unable to restore growth to a Legionella icmQ mutant. Thus, Coxiella encodes functional components of a type IV secretion system expressed in vivo that is mechanistically related to the Legionella Dot/Icm apparatus. These studies suggest that a dot/icm‐related secretion system could play an important role in creating the specialized vacuole that supports Coxiella replication.
Multiple transporters associated with malaria parasite responses to chloroquine and quinine
Authors: Mu Jianbing , Ferdig Michael T. , Feng Xiaorong , Joy Deirdre A. , Duan Junhui , Furuya Tetsuya , Subramanian G. , Aravind L. , Cooper Roland A. , Wootton John C. , Xiong Momiao , Su Xin‐zhuan
Published: July 2003

Mutations and/or overexpression of various transporters are known to confer drug resistance in a variety of organisms. In the malaria parasite Plasmodium falciparum, a homologue of P‐glycoprotein, PfMDR1, has been implicated in responses to chloroquine (CQ), quinine (QN) and other drugs, and a putative transporter, PfCRT, was recently demonstrated to be the key molecule in CQ resistance. However, other unknown molecules are probably involved, as different parasite clones carrying the same pfcrt and pfmdr1 alleles show a wide range of quantitative responses to CQ and QN. Such molecules may contribute to increasing incidences of QN treatment failure, the molecular basis of which is not understood. To identify additional genes involved in parasite CQ and QN responses, we assayed the in vitro susceptibilities of 97 culture‐adapted cloned isolates to CQ and QN and searched for single nucleotide polymorphisms (SNPs) in DNA encoding 49 putative transporters (total 113 kb) and in 39 housekeeping genes that acted as negative controls. SNPs in 11 of the putative transporter genes, including pfcrt and pfmdr1, showed significant associations with decreased sensitivity to CQ and/or QN in P. falciparum. Significant linkage disequilibria within and between these genes were also detected, suggesting interactions among the transporter genes. This study provides specific leads for better understanding of complex drug resistances in malaria parasites.
The BceRS two‐component regulatory system induces expression of the bacitracin transporter, BceAB, in Bacillus subtilis
Authors: Ohki Reiko , Giyanto  , Tateno Kozue , Masuyama Waka , Moriya Shigeki , Kobayashi Kazuo , Ogasawara Naotake
Published: July 2003

BceA and bceB encode a nucleotide‐binding domain (NBD) and membrane‐spanning domain (MSD) subunit, respectively, of an ATP‐binding cassette (ABC) transporter in Bacillus subtilis. Disruption of these genes resulted in hypersensitivity to bacitracin, a peptide antibiotic that is non‐ribosomally synthesized in some strains of Bacillus. Northern hybridization analyses showed that expression of the bceAB operon is induced by bacitracin present in the growth medium. The bceRS genes encoding a two‐component regulatory system are located immediately upstream of bceAB. Deletion analyses of the bceAB promoter together with DNase I footprinting experiments revealed that a sensor kinase, BceS, responds to extracellular bacitracin either directly or indirectly and transmits a signal to a cognate response regulator, BceR. The regulator binds directly to the upstream region of the bceAB promoter and upregulates the expression of bceAB genes. The bcrC gene product is additionally involved in bacitracin resistance. The expression of bcrC is dependent on the ECF σ factors, σM and σX, but not on the BceRS two‐component system. In view of these results, possible roles of BceA, BceB and BcrC in bacitracin resistance of B. subtilis 168 are discussed.
An intramolecular disulphide bond reduces the efficacy of a lipoprotein plasma membrane sorting signal
Authors: Robichon Carine , Bonhivers Mélanie , Pugsley Anthony P.
Published: July 2003

To study lipoprotein sorting in Escherichia coli, we devised a novel screen in which sensitivity or resistance to bacteriophage T5 and colicin M reflects the membrane localization of the bacteriophage T5‐encoded lipoprotein Llp, which inactivates the outer membrane (OM) T5 receptor (FhuA). When processed by lipoprotein signal peptidase, Llp has a serine at position +2, immediately after the fatty acylated N‐terminal cysteine. As predicted by the ‘+2 lipoprotein sorting rule’ that determines the localization of lipoproteins in the cell envelope, Llp is located in the OM. However, contrary to expectations, when serine +2 was replaced by aspartate, the canonical plasma membrane lipoprotein retention signal, Llp was still ≥ 40% targeted to the OM and protected cells against colicin M and phage T5. OM association of this Llp derivative was abolished when a peptide spacer was inserted between the aspartate and the rest of Llp or when the formation of an intramolecular disulphide bond in Llp was prevented by substituting one or other of the cysteines involved. Furthermore, analysis of a MalE–Llp hybrid protein with or without a lipid moiety demonstrated that fatty acylation of Llp is essential for its OM association and for protection against colicin M and bacteriophage T5. These data suggest (i) that phage‐encoded Llp uses the endogenous E. coli Lol pathway for lipoprotein sorting to the OM and (ii) that the conformation of a lipoprotein can affect its sorting within the cell envelope.
In vivo magnetic resonance imaging of xylem vessel contents in woody lianas
Authors: CLEARWATER M. J. , CLARK C. J.
Published: July 2003

Previous reports suggest that in some plant species the refilling of embolized xylem vessels can occur while negative pressure exists in the xylem. The aim of this experiment was to use non‐destructive nuclear magnetic resonance imaging (MRI) to study the dynamics of xylem cavitation and embolism repair in‐vivo. Serial 1H‐MRI was used to monitor the contents of xylem vessels in stems of two dicotyledonous (Actinidia deliciosa and Actinidia chinensis, kiwifruit) and one monocotyledonous (Ripogonum scandens, supplejack) species of woody liana. The configuration of the horizontal wide bore magnet and probe allowed the imaging of woody stems up to 20 mm in diameter. Tests using excised stems confirmed that the image resolution of 78 µm and digital image subtraction could be used to detect the emptying and refilling of individual vessels. Imaging was conducted on both intact plants and excised shoots connected to a water supply. In the case of Ripogonum the excised shoots were long enough to allow the distal end of the shoot, including all leaves, to be exposed to ambient conditions outside the building while the proximal end was inside the MRI magnet. In total, six stems were monitored for 240 h while the shoots were subjected to treatments that included light and dark periods, water stress followed by re‐watering, and the covering of all leaves to prevent transpiration. The sudden emptying of water‐filled vessels occurred frequently while xylem water potential was low (below −0.5 MPa for Actinidia, −1.0 MPa for Ripogonum), and less frequently after xylem water potential approached zero at the end of water‐stress treatments. No refilling of empty vessels was observed at any time in any of the species examined. It is concluded that embolism repair under negative pressure does not occur in the species examined here. Embolism repair may be more likely in species with narrower xylem vessels, but further experiments are required with other species before it can be concluded that repair during transpiration is a widespread phenomenon.
Transfer conductance in second growth Douglas‐fir (Pseudotsuga menziesii (Mirb.)Franco) canopies
Authors: WARREN C. R. , ETHIER G. J. , LIVINGSTON N. J. , GRANT N. J. , TURPIN D. H. , HARRISON D. L. , BLACK T. A.
Published: July 2003

The internal conductance from intercellular spaces to the sites of carboxylation (gi) has only been measured in a few tree species and not in conifers, despite the fact it may impose a large limitation on photosynthesis. The present study provides the first estimates of gi for a coniferous species, and examines variation in gi with height and its relationships to anatomical, biochemical and physiological traits. Measurements were made on upper and lower canopy current‐year needles of 50‐year‐old Douglas‐fir (Pseudotsuga menziesii (Mirb.) Franco). Needle thickness and specific leaf area decreased by 30% from the top to bottom of the canopy. These anatomical/morphological changes were accompanied by modest variation in allocation of N to chlorophyll and the chlorophyll a/b ratio. Allocation of N to Rubisco did not vary with height, but the ratio of Rubisco to chlorophyll did owing to the aforementioned changes in allocation to chlorophyll. The value of gi was estimated in one tree from concurrent measurements of carbon isotope discrimination and net photosynthesis. To examine the variation in gi among trees a second independent method based on day respiration and the difference between the chloroplastic and intercellular photocompensation points (photocompensation point method) was used. Estimates of gi obtained by the two methods agreed well with values varying between 0.14 and 0.20 mol m−2 s−1. It is estimated that gi limits photosynthesis by approximately 20% as compared to an approximately 30% stomatal limitation (under well‐watered conditions). The value of gi scaled approximately with maximum rates of photosynthesis, which were significantly greater in upper canopy needles. Nevertheless, gi did not vary significantly with canopy height, owing to greater variability in gi than photosynthesis.
Nitrate photo‐assimilation in tomato leaves under short‐term exposure to elevated carbon dioxide and low oxygen
Authors: SEARLES P. S. , BLOOM A. J.
Published: July 2003

The role of photorespiration in the foliar assimilation of nitrate (NO3–) and carbon dioxide (CO2) was investigated by measuring net CO2 assimilation, net oxygen (O2) evolution, and chlorophyll fluorescence in tomato leaves (Lycopersicon esculentum). The plants were grown under ambient CO2 with ammonium nitrate (NH4NO3) as the nitrogen source, and then exposed to a CO2 concentration of either 360 or 700 µmol mol−1, an O2 concentration of 21 or 2%, and either NO3– or NH4+ as the sole nitrogen source. The elevated CO2 concentration stimulated net CO2 assimilation under 21% O2 for both nitrogen treatments, but not under 2% O2. Under ambient CO2 and O2 conditions (i.e. 360 µmol mol−1 CO2, 21% O2), plants that received NO3– had 11–13% higher rates of net O2 evolution and electron transport rate (estimated from chlorophyll fluorescence) than plants that received NH4+. Differences in net O2 evolution and electron transport rate due to the nitrogen source were not observed at the elevated CO2 concentration for the 21% O2 treatment or at either CO2 level for the 2% O2 treatment. The assimilatory quotient (AQ) from gas exchange, the ratio of net CO2 assimilation to net O2 evolution, indicated more NO3– assimilation under ambient CO2 and O2 conditions than under the other treatments. When the AQ was derived from gross O2 evolution rates estimated from chlorophyll fluorescence, no differences could be detected between the nitrogen treatments. The results suggest that short‐term exposure to elevated atmospheric CO2 decreases NO3– assimilation in tomato, and that photorespiration may help to support NO3– assimilation.
Sugar transport together with environmental conditions controls time lags between xylem and stem diameter changes
Authors: SEVANTO S. , VESALA T. , PERÄMÄKI M. , NIKINMAA E.
Published: July 2003

In the present study the seasonal patterns of time lags between diurnal xylem and whole stem diameter variations at the top and at the base of two Scots pine trees (Pinus sylvestris L.) were compared. The diameter variations were measured during the summers of 2001 and 2002. Time lags were determined using the cross‐correlation method. The lags were found to vary in time according to the different stages of growth. At the top the xylem lagged behind the whole stem between the beginning of stem growth and the end of shoot growth in both years. In 2001 the time lags at the base showed a similar behaviour during stem growth. That kind of seasonal pattern of the time lags would result from the changes in the sink strength due to changing growth rate at different parts of the tree and the differences in the annual rhythm of growth and water availability in the soil (based on precipitation measurements) between the years 2001 and 2002 were reflected in the patterns. The time lags of shrinking and swelling periods during high and low photosynthetic activity (measured using a shoot chamber) were also compared. It was found, for example, that in 2001 in the middle of the growing season at the top of the tree the whole stem lagged on average 15 min more behind the xylem on the days of high photosynthetic activity than on the days of low or moderate. These results show for the first time that the transportation of carbohydrates and variable sink activity could be detected during the growing season in field conditions using stem and xylem diameter variation measurements. Furthermore, these results provide evidence of the pressure gradient‐driven flow also in the phloem of gymnosperms.
Differences in hydraulic architecture account for near‐isohydric and anisohydric behaviour of two field‐grown Vitis vinifera L. cultivars during drought
Authors: SCHULTZ H. R.
Published: July 2003

A comparative study on stomatal control under water deficit was conducted on grapevines of the cultivars Grenache, of Mediterranean origin, and Syrah of mesic origin, grown near Montpellier, France and Geisenheim, Germany. Syrah maintained similar maximum stomatal conductance (gmax) and maximum leaf photosynthesis (Amax) values than Grenache at lower predawn leaf water potentials, Ψleaf, throughout the season. The Ψleaf of Syrah decreased strongly during the day and was lower in stressed than in watered plants, showing anisohydric stomatal behaviour. In contrast, Grenache showed isohydric stomatal behaviour in which Ψleaf did not drop significantly below the minimum Ψleaf of watered plants. When g was plotted versus leaf specific hydraulic conductance, Kl, incorporating leaf transpiration rate and whole‐plant water potential gradients, previous differences between varieties disappeared both on a seasonal and diurnal scale. This suggested that isohydric and anisohydric behaviour could be regulated by hydraulic conductance. Pressure‐flow measurements on excised organs from plants not previously stressed revealed that Grenache had a two‐ to three‐fold larger hydraulic conductance per unit path length (Kh) and a four‐ to six‐fold larger leaf area specific conductivity (LSC) in leaf petioles than Syrah. Differences between internodes were only apparent for LSC and were much smaller. Cavitation detected as ultrasound acoustic emissions on air‐dried shoots showed higher rates for Grenache than Syrah during the early phases of the dry‐down. It is hypothesized that the differences in water‐conducting capacity of stems and especially petioles may be at the origin of the near‐isohydric and anisohydric behaviour of g.
Expression of low molecular weight heat‐shock proteins and total antioxidant activity in the Mediterranean tree Quercus ilex L. in relation to seasonal and diurnal changes in physiological parameters
Authors: VERDAGUER D. , ARANDA X. , JOFRÉ A. , EL OMARI B. , MOLINAS M. , FLECK I.
Published: July 2003

The total antioxidant activity (TAA) and the accumulation of small heat shock proteins (sHsps) were analysed under field conditions in Quercus ilex with regard to organ ontogeny and the physiological state of the plant. The results point toward the participation of sHsps and an increase of TAA in the general adaptation syndrome (GAS) of woody Mediterranean evergreens. In leaves and stems, there was a definite TAA seasonal pattern but no effect from diurnal variations or from the current stage of organ ontogeny. TAA was about twice as large in summer as in spring and winter and the hydrophilic antioxidant content was about 16 times greater than that of lipophilic antioxidants. The accumulation of sHsps in leaves also showed a seasonal pattern, but no effect from diurnal variations or from leaf ontogeny. In summer days, the sHsps content remained invariable even during the daylight hours in which the leaves were physiologically recovered. However, the accumulation of sHsps in stems did vary in relation to organ ontogeny. Old stems had a high accumulation of sHsps throughout the year, whereas in young stems, accumulation of sHsps was detected only in summer. This is probably due to a higher quantity of lignified and suberized tissues in the older stems. Using two‐dimensional immunodetection for leaves and stems, two sets of Hs protein species (17 and 10 kDa regions) were observed. In stems, there was an increase in 10 kDa proteins from winter to summer. These results are discussed and the possible role of the two types of polypeptides in the face of environmental and endogenous oxidative stress are considered.
Evaluation of root damage to English walnut caused by five Phytophthora species
Authors: Vettraino A. M. , Belisario A. , Maccaroni M. , Vannini A.
Published: July 2003

The pathogenicity of five species of Phytophthora to English walnut was studied in a greenhouse experiment. Phytophthora cinnamomi was the most aggressive species, causing severe root rot and seedling mortality. The other species tested, P. cambivora, P. citricola, P. cactorum and P. cryptogea, did not induce visible crown symptoms on seedlings 2 months after inoculation. Some strains of P. cambivora and P. cactorum also caused taproot damage to seedlings. All except one of the tested isolates caused significant necrosis of fine roots and a significant reduction of root weight compared with noninoculated seedlings. Reduction of above‐ground plant development was not statistically significant. While P. cinnamomi is well known as an aggressive primary pathogen of English walnut, the other species of Phytophthora may act as predisposing factors to walnut decline, affecting root system development and increasing host vulnerability to environmental stress.
Seasonal detection of pear decline phytoplasma by nested‐PCR in different pear cultivars
Authors: Garcia‐Chapa M. , Medina V. , Viruel M. A. , Laviña A. , Batlle A.
Published: July 2003

Seasonal detection of pear decline phytoplasma was studied in three pear cultivars: Bartlett, Limonera and Blanquilla. Samples from 43 infected trees were collected monthly over 2 years and analysed by nested PCR. The three cultivars each showed a different pattern of phytoplasma detection. The maximum detection rate of pear decline phytoplasma occurred in December in the three orchards, and it remained high throughout the winter months. In spring, when new buds appeared and sap was produced, the detection rate decreased. Leaf midribs, buds and stems were compared to determine which sample was more reliable for phytoplasma detection. The best indicators were stems. The presence of phytoplasma in sieve tubes during the dormant season was determined by grafting. The results suggest that phytoplasmas could overwinter in shoots, with the implication that vegetative propagation during this period could also disseminate the disease.
Irvingia, a forest host of the cocoa black‐pod pathogen, Phytophthora megakarya, in Cameroon
Authors: Holmes K. A. , Evans H. C. , Wayne S. , Smith J.
Published: July 2003

Phytophthora megakarya is an increasingly important invasive pathogen of cocoa in West Africa, where it forms part of the black‐pod disease complex together with the more widespread, but less aggressive, P. palmivora. Its purported centre of diversity, based on evidence from molecular studies and mating types, lies on the Cameroon–Nigeria border, from where it has spread throughout both countries and more recently into Ghana and the Ivory Coast. A survey undertaken in an ancient primary forest (Korup National Park) in western Cameroon, adjacent to the Nigerian border, identified Irvingia sp., close to I. gabonensis (Irvingiaceae), as a wild host of P. megakarya, using both morphological and molecular characterization. ITS fingerprinting of two additional Phytophthora isolates, obtained during a supplementary survey in central Cameroon, showed identical banding patterns for the isolate from a cocoa pod, whilst the isolate from an unknown forest fruit proved to belong to P. heveae. This is the first authenticated record of P. heveae from the African continent. Subsequent AFLP analysis grouped the two P. megakarya isolates with other Cameroonian isolates held in the CABI Genetic Resource Collection, but separated them from the Ghanaian isolates.