bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Source Leaf Responses to Water-Deficit Stresses in Cotton Using a Novel Stress Bioassay
Authors: Burke John J. 
Published: October 2006

Abstract
Water-deficit stresses preferentially reduce shoot growth, thereby disrupting the flow of carbohydrates from source leaves to the developing sinks. Here, we use a novel stress bioassay to dissect responses of field and greenhouse-grown cotton (Gossypium hirsutum) source leaves to water-deficit stresses. Fifth main stem leaf samples were harvested at sunrise and subjected to a prolonged elevated respiratory demand in the dark. Sucrose levels are lower in nonstressed cotton at sunrise compared to water-deficit stressed cotton, potentially predisposing the nonstressed tissue to succumb more rapidly. Tissue death was determined initially using the cell viability stain 2,3,5-triphenyltetrazolium chloride, but was determined in subsequent experiments by monitoring the decline in chlorophyll fluorescence yield. Fluorescence yield measurements were obtained within minutes of harvesting and individual samples were monitored over the time course of the treatment. Analyses of the time course and magnitude of chlorophyll fluorescence yield decline in samples from irrigated and dryland plots permitted the detection of stress responses within 24 h of the cessation of irrigation. The rate of fluorescence yield decline during the elevated respiratory demand treatment slowed as the water-deficit stress increased. Upon irrigation, the source leaves of the water-stressed plants recovered to prestress values within 4 d. Well-watered cotton overexpressing heat shock protein 101 had identical rates of fluorescence yield decline as nontransgenic cotton. These results suggest that the delayed decline in fluorescence yield of water-stressed tissue exposed to prolonged elevated respiratory demand can be used as a sensitive indicator of water-deficit stress responses.
Arabidopsis Orthologs of Maize Chloroplast Splicing Factors Promote Splicing of Orthologous and Species-Specific Group II Introns
Authors: Asakura Yukari , Barkan Alice 
Published: October 2006

Abstract
Chloroplast genomes in plants and green algae contain numerous group II introns, large ribozymes that splice via the same chemical steps as spliceosome-mediated splicing in the nucleus. Most chloroplast group II introns are degenerate, requiring interaction with nucleus-encoded proteins to splice in vivo. Genetic approaches in maize (Zea mays) and Chlamydomonas reinhardtii have elucidated distinct sets of proteins that assemble with chloroplast group II introns and facilitate splicing. Little information is available, however, concerning these processes in Arabidopsis (Arabidopsis thaliana). To determine whether the paucity of data concerning chloroplast splicing factors in Arabidopsis reflects a fundamental difference between protein-facilitated group II splicing in monocot and dicot plants, we examined the mutant phenotypes associated with T-DNA insertions in Arabidopsis genes encoding orthologs of the maize chloroplast splicing factors CRS1, CAF1, and CAF2 (AtCRS1, AtCAF1, and AtCAF2). We show that the splicing functions and intron specificities of these proteins are largely conserved between maize and Arabidopsis, indicating that these proteins were recruited to promote the splicing of plastid group II introns prior to the divergence of monocot and dicot plants. We show further that AtCAF1 promotes the splicing of two group II introns, rpoC1 and clpP-intron 1, that are found in Arabidopsis but not in maize; AtCAF1 is the first splicing factor described for these introns. Finally, we show that a strong AtCAF2 allele conditions an embryo-lethal phenotype, adding to the body of data suggesting that cell viability is more sensitive to the loss of plastid translation in Arabidopsis than in maize.
A Sodium Transporter (HKT7) Is a Candidate forNax1, a Gene for Salt Tolerance in Durum Wheat
Authors: Huang Shaobai , Spielmeyer Wolfgang , Lagudah Evans S. , James Richard A. , Platten J. Damien , Dennis Elizabeth S. , Munns Rana 
Published: October 2006

AbstractDurum wheat (Triticum turgidum subsp. durum) is more salt sensitive than bread wheat (Triticum aestivum). A novel source of Na+ exclusion conferring salt tolerance to durum wheat is present in the durum wheat Line 149 derived from Triticum monococcum C68-101, and a quantitative trait locus contributing to low Na+ concentration in leaf blades, Nax1, mapped to chromosome 2AL. In this study, we used the rice (Oryza sativa) genome sequence and data from the wheat expressed sequence tag deletion bin mapping project to identify markers and construct a high-resolution map of the Nax1 region. Genes on wheat chromosome 2AL and rice chromosome 4L had good overall colinearity, but there was an inversion of a chromosomal segment that includes the Nax1 locus. Two putative sodium transporter genes (TmHKT7) related to OsHKT7 were mapped to chromosome 2AL. One TmHKT7 member (TmHKT7-A1) was polymorphic between the salt-tolerant and -sensitive lines, and cosegregated with Nax1 in the high-resolution mapping family. The other TmHKT7 member (TmHKT7-A2) was located within the same bacterial artificial chromosome contig of approximately 145 kb as TmHKT7-A1. TmHKT7-A1 and -A2 showed 83% amino acid identity. TmHKT7-A2, but not TmHKT7-A1, was expressed in roots and leaf sheaths of the salt-tolerant durum wheat Line 149. The expression pattern of TmHKT7-A2 was consistent with the physiological role of Nax1 in reducing Na+ concentration in leaf blades by retaining Na+ in the sheaths. TmHKT7-A2 could control Na+ unloading from xylem in roots and sheaths.
Plant Glutathione Peroxidases Are Functional Peroxiredoxins Distributed in Several Subcellular Compartments and Regulated during Biotic and Abiotic Stresses
Authors: Navrot Nicolas , Collin Valérie , Gualberto José , Gelhaye Eric , Hirasawa Masakazu , Rey Pascal , Knaff David B. , Issakidis Emmanuelle , Jacquot Jean-Pierre , Rouhier Nicolas 
Published: October 2006

AbstractWe provide here an exhaustive overview of the glutathione (GSH) peroxidase (Gpx) family of poplar (Populus trichocarpa). Although these proteins were initially defined as GSH dependent, in fact they use only reduced thioredoxin (Trx) for their regeneration and do not react with GSH or glutaredoxin, constituting a fifth class of peroxiredoxins. The two chloroplastic Gpxs display a marked selectivity toward their electron donors, being exclusively specific for Trxs of the y type for their reduction. In contrast, poplar Gpxs are much less specific with regard to their electron-accepting substrates, reducing hydrogen peroxide and more complex hydroperoxides equally well. Site-directed mutagenesis indicates that the catalytic mechanism and the Trx-mediated recycling process involve only two (cysteine [Cys]-107 and Cys-155) of the three conserved Cys, which form a disulfide bridge with an oxidation-redox midpoint potential of −295 mV. The reduction/formation of this disulfide is detected both by a shift on sodium dodecyl sulfate-polyacrylamide gel electrophoresis or by measuring the intrinsic tryptophan fluorescence of the protein. The six genes identified coding for Gpxs are expressed in various poplar organs, and two of them are localized in the chloroplast, with one colocalizing in mitochondria, suggesting a broad distribution of Gpxs in plant cells. The abundance of some Gpxs is modified in plants subjected to environmental constraints, generally increasing during fungal infection, water deficit, and metal stress, and decreasing during photooxidative stress, showing that Gpx proteins are involved in the response to both biotic and abiotic stress conditions.
MIKC* MADS-Protein Complexes Bind Motifs Enriched in the Proximal Region of Late Pollen-Specific Arabidopsis Promoters
Authors: Verelst Wim , Saedler Heinz , Münster Thomas 
Published: October 2006

AbstractThe genome of Arabidopsis (Arabidopsis thaliana) encodes over 100 MADS-domain transcription factors, categorized into five phylogenetic subgroups. Most research efforts have focused on just one of these subgroups (MIKCc), whereas the other four remain largely unexplored. Here, we report on five members of the so-called Mδ or Arabidopsis MIKC* (AtMIKC*) subgroup, which are predominantly expressed during the late stages of pollen development. Very few MADS-box genes function in mature pollen, and from this perspective, the AtMIKC* genes are therefore highly exceptional. We found that the AtMIKC* proteins are able to form multiple heterodimeric complexes in planta, and that these protein complexes exhibit a for the MADS-family unusual and high DNA binding specificity in vitro. Compared to their occurrence in promoters genome wide, AtMIKC* binding sites are strongly overrepresented in the proximal region of late pollen-specific promoters. By combining our experimental data with in silico genomics and pollen transcriptomics approaches, we identified a considerable number of putative direct target genes of the AtMIKC* transcription factor complexes in pollen, many of which have known or proposed functions in pollen tube growth. The expression of several of these predicted targets is altered in mutant pollen in which all AtMIKC* complexes are affected, and in vitro germination of this mutant pollen is severely impaired. Our data therefore suggest that the AtMIKC* protein complexes play an essential role in transcriptional regulation during late pollen development.
tie-dyed1Regulates Carbohydrate Accumulation in Maize Leaves
Authors: Braun David M. , Ma Yi , Inada Noriko , Muszynski Michael G. , Baker R. Frank 
Published: October 2006

AbstractAcquisition of cell identity requires communication among neighboring cells. To dissect the genetic pathways regulating cell signaling in later leaf development, a screen was performed to identify mutants with chloroplast pigmentation sectors that violate cell lineage boundaries in maize (Zea mays) leaves. We have characterized a recessive mutant, tie-dyed1 (tdy1), which develops stable, nonclonal variegated yellow and green leaf sectors. Sector formation requires high light, occurs during a limited developmental time, and is restricted to leaf blade tissue. Yellow tdy1 sectors accumulate excessive soluble sugars and starch, whereas green sectors appear unaffected. Significantly, starch accumulation precedes chlorosis in cells that will become a yellow sector. Retention of carbohydrates in tdy1 leaves is associated with a delay in reproductive maturity, decreased stature, and reduced yield. To explain the tdy1 sectoring pattern, we propose a threshold model that incorporates the light requirement and the hyperaccumulation of photoassimilates. A possible function consistent with this model is that TDY1 acts as a sugar sensor to regulate an inducible sugar export pathway as leaves develop under high light conditions.
Backbone dynamics of SDF‐1α determined by NMR: Interpretation in the presence of monomer–dimer equilibrium
Authors: Baryshnikova Olga K. , Sykes Brian D. 
Published: October 2006

AbstractSDF‐1α is a member of the chemokine family implicated in various reactions in the immune system. The interaction of SDF‐1α with its receptor, CXCR4, is responsible for metastasis of a variety of cancers. SDF‐1α is also known to play a role in HIV‐1 pathogenesis. The structures of SDF‐1α determined by NMR spectroscopy have been shown to be monomeric while X‐ray structures are dimeric. Biochemical data and in vivo studies suggest that dimerization is likely to be important for the function of chemokines. We report here the dynamics of SDF‐1α determined through measurement of main chain 15N NMR relaxation data. The data were obtained at several concentrations of SDF‐1α and used to determine a dimerization constant of ∼5 mM for a monomer–dimer equilibrium. The dimerization constant was subsequently used to extrapolate values for the relaxation data corresponding to monomeric SDF‐1α. The experimental relaxation data and the extrapolated data for monomeric SDF‐1α were analyzed using the model free approach. The model free analysis indicated that SDF‐1α is rigid on the nano‐ to picosecond timescale with flexible termini. Several residues involved in the dimer interface display slow micro‐ to millisecond timescale motions attributable to chemical exchange such as monomer–dimer equilibrium. NMR relaxation measurements are shown to be applicable for studying oligomerization processes such as the dimerization of SDF‐1α.
Solution structure of the kinase‐associated domain 1 of mouse microtubule‐associated protein/microtubule affinity‐regulating kinase 3
Authors: Tochio Naoya , Koshiba Seizo , Kobayashi Naohiro , Inoue Makoto , Yabuki Takashi , Aoki Masaaki , Seki Eiko , Matsuda Takayoshi , Tomo Yasuko , Motoda Yoko , Kobayashi Atsuo , Tanaka Akiko , Hayashizaki Yoshihide , Terada Takaho , Shirouzu Mikako , Kigawa Takanori , Yokoyama Shigeyuki 
Published: October 2006

AbstractMicrotubule‐associated protein/microtubule affinity‐regulating kinases (MARKs)/PAR‐1 are common regulators of cell polarity that are conserved from nematode to human. All of these kinases have a highly conserved C‐terminal domain, which is termed the kinase‐associated domain 1 (KA1), although its function is unknown. In this study, we determined the solution structure of the KA1 domain of mouse MARK3 by NMR spectroscopy. We found that ∼50 additional residues preceding the previously defined KA1 domain are required for its proper folding. The newly defined KA1 domain adopts a compact α+β structure with a βαββββα topology. We also found a characteristic hydrophobic, concave surface surrounded by positively charged residues. This concave surface includes the highly conserved Glu‐Leu‐Lys‐Leu motif at the C terminus, indicating that it is important for the function of the KA1 domain.
Predictors of refill non‐adherence in patients with heart failure
Authors: George Johnson , Shalansky Stephen J. 
Published: October 2006

What is already known about this subject• Non‐adherence to recommended treatment is common in patients with heart failure and is associated with poor outcomes.• Personal beliefs as well as experiences with medications and illness could influence medication use.What this study adds• Perception regarding barrier to medication use was a stronger predictor of non‐adherence than demographic or clinical variables.• Patients who were non‐adherent to nonpharmacological management of heart failure were more likely to be non‐adherent to their medications.• Regimen complexity should not be considered in isolation when strategies for addressing adherence issues are designed.AimTo identify the health beliefs and patient characteristics associated with medication non‐adherence in patients attending a heart failure outpatient clinic.MethodsA survey was administered to 350 consenting clinic patients. Questions focused on relevant demographic and clinical characteristics, the Health Belief Model, the Beliefs About Medicines Questionnaire and the Multidimensional Health Locus of Control. Multivariate logistic regression was used to identify independent predictors of refill non‐adherence (<90%).ResultsRefill non‐adherence was found in 77 (22%) participants. Being a smoker [odds ratio (OR) 2.4, 95% confidence interval (CI) 1.0, 5.8, P = 0.045], two or fewer medication administration times (OR 2.4, 95% CI 1.2, 4.6, P = 0.01), and positive response to ‘Have you changed your daily routine to accommodate your heart failure medication schedule’ (OR 2.4, 95% CI 1.2, 4.5, P = 0.01) were the independent predictors of refill non‐adherence.ConclusionPerceptions regarding barriers to medication taking and fewer administration times could result in medication non‐adherence in congestive heart failure patients. Medication regimens should be designed after accounting for patients' existing routines.
SHOX mutations in idiopathic short stature and Leri‐Weill dyschondrosteosis: frequency and phenotypic variability
Authors: Jorge Alexander A. L. , Souza Silvia C. , Nishi Miriam Y. , Billerbeck Ana E. , Libório Débora C. C. , Kim Chong A. , Arnhold Ivo J. P. , Mendonca Berenice B. 
Published: October 2006

SummaryObjective  The frequency of SHOX mutations in children with idiopathic short stature (ISS) has been found to be variable. We analysed the SHOX gene in children with ISS and Leri‐Weill dyschondrosteosis (LWD) and evaluated the phenotypic variability in patients harbouring SHOX mutations.Patients  Sixty‐three ISS, nine LWD children and 21 affected relatives.Methods  SHOX gene deletion was evaluated by fluorescence in situ hybridization (FISH), Southern blotting and segregation study of polymorphic marker. Point mutations were assessed by direct DNA sequencing.Results  None of the ISS patients presented SHOX deletions, but two (3·2%) presented heterozygous point mutations, including the novel R147H mutation. However, when ISS patients were selected by sitting height : height ratio (SH/H) for age > 2 SD, mutation frequency detection increased to 22%. Eight (89%) LWD patients had SHOX deletions, but none had point mutations. Analysis of the other relatives in the families carrying SHOX mutations identified 14 children and 17 adult patients. A broad phenotypic variability was observed in all families regarding short stature severity and Madelung deformities. However, the presence of disproportional height, assessed by SH/H, was observed in all children and 82% of adult patients, being the most common feature in our patients with SHOX mutations.Conclusion  Patients with SHOX mutations present a broad phenotypic variability. SHOX mutations are very frequent in LWD (89%), in opposition to ISS (3·2%) in our cohort. The use of SH/H SDS as a selection criterion increases the frequency of SHOX mutation detection to 22% and should be used for selecting ISS children to undergo SHOX mutation molecular studies.
Theoretical model of coping among relatives of patients in intensive care units: a simultaneous concept analysis
Authors: Johansson Ingrid , Hildingh Cathrine , Wenneberg Stig , Fridlund Bengt , Ahlström Gerd 
Published: October 2006

Aim.  This paper reports the development of a theoretical model of relatives’ coping approaches during the patient's intensive care unit stay and subsequent recovery at home by performing an analysis of concepts generated from two empirically grounded, theoretical studies in this area.Background.  When supporting relatives of intensive care unit patients, it is important that nurses have access to evidence‐based knowledge of relatives’ coping approaches during the period of illness and recovery.Method.  Simultaneous concept analysis was used to refine and combine multiple coping concepts into a theoretical model of coping. The concepts were generated in two previous empirical studies of relatives’ coping approaches during mechanically ventilated patients’ intensive care unit stays and recovery at home.Findings.  The theoretical model was developed in 2004–2005 and illustrates the effectiveness of different coping approaches in relation to each other and to social support. Definitions summarizing each coping approach and containing the knowledge gained through the simultaneous concept analysis method were also formulated.Conclusion.  This middle‐range theory of relatives’ coping approaches may make a valuable contribution to international intensive care unit nursing practice, especially as it is based on empirical studies and may therefore serve as a basis for the development of future clinical guidelines. However, the theoretical model needs to be empirically validated before it can be used.
Development of a framework for person‐centred nursing
Authors: McCormack Brendan , McCance Tanya V. 
Published: October 2006

Aim.  This paper presents the development and content of a person‐centred nursing framework.Background and rationale.  Person‐centred is a widely used concept in nursing and health care generally, and a range of literature articulates key components of person‐centred nursing. This evidence base highlights the links between this approach and previous work on therapeutic caring.Methods.  The framework was developed through an iterative process and involved a series of systematic steps to combine two existing conceptual frameworks derived from empirical studies. The process included the mapping of original conceptual frameworks against the person‐centred nursing and caring literature, critical dialogue to develop a combined framework, and focus groups with practitioners and co‐researchers in a larger person‐centred nursing development and research project to test its face validity.Findings.  The person‐centred nursing framework comprises four constructs –prerequisites, which focus on the attributes of the nurse; the care environment, which focuses on the context in which care is delivered; person‐centred processes, which focus on delivering care through a range of activities; and expected outcomes, which are the results of effective person‐centred nursing. The relationship between the constructs suggests that, to deliver person‐centred outcomes, account must be taken of the prerequisites and the care environment that are necessary for providing effective care through the care processes.Conclusion.  The framework described here has been tested in a development and research project in an acute hospital setting. Whilst there is an increasing empirical base for person‐centred nursing, as yet little research has been undertaken to determine its outcomes for patients and nurses. The framework developed can be described as a mid‐range theory. Further testing of the framework through empirical research is required to establish its utility for nursing practice and research.
Control of functional mRNA stability in bacteria: multiple mechanisms of nucleolytic and non‐nucleolytic inactivation
Authors: Petersen C. 
Published: October 2006

SummaryMessenger RNA in bacteria may be inactivated by several parallel mechanisms acting independently on different target sites. For any species of mRNA the overall rate of inactivation is determined by the sum of the contributions from the different mechanisms. Transcripts may be inactivated directly by endonucleolytic attack or by processive nucleolytic degradation, which may proceed in the 3′–5′ direction and probably also in the 5′‐3′ direction. Moreover, the functional lifetime of many mRNAs may be determined by processes that are not nucleolytic, such as the binding of translational repressors or the formation of secondary structures which prevent initiation of translation. These non‐nucleolytic processes may also determine the chemical stability as chemical degradation frequently appears to be closely coupled to functional inactivation. The relative importance of the different mechanisms in the inactivation of bulk cellular mRNA, as well as the general prospects for engineering of stable mRNAs are discussed.
D‐E‐A‐D protein family of putative RNA helicases
Authors: Schmid S. R. , Linder P. 
Published: October 2006

SummaryRNA metabolism plays a central role in cell growth. It is essential to regulate RNA synthesis, processing, stability and degradation. Conformational changes in RNA are key elements in regulating cellular processes. Recently, an increasing number of putative RNA helicases from different organisms ranging from Escherichia coli to humans and viruses have been identified. They are Involved in diverse cellular functions such as RNA splicing, ribosome assembly, initiation of translation, spermatogenesis, embryogenesis, and cell growth and division. Based on sequence homologies these proteins were grouped in a family, the D‐E‐A‐D box protein family (D‐E‐A‐D = Asp‐Glu‐Ala‐Asp). Some of the better characterized members have been shown to possess ATP‐binding and hydrolysing activities as well as ATP‐dependent RNA helicase activities. Most of the genes encoding such proteins have been isolated from yeast, on which we will focus in this review. From sequence data, three of the members form a subfamily, the D‐E‐A‐H subfamily.