bluuebunny/crossref_metadata_2025_split huggingface dataset:
tie-dyed1Functions Non-Cell Autonomously to Control Carbohydrate Accumulation in Maize Leaves
Authors: Baker R. Frank , Braun David M. 
Published: April 2007

AbstractThe tie-dyed1 (tdy1) mutant of maize (Zea mays) produces chlorotic, anthocyanin-accumulating regions in leaves due to the hyperaccumulation of carbohydrates. Based on the nonclonal pattern, we propose that the accumulation of sucrose (Suc) or another sugar induces the tdy1 phenotype. The boundaries of regions expressing the tdy1 phenotype frequently occur at lateral veins. This suggests that lateral veins act to limit the expansion of tdy1 phenotypic regions by transporting Suc out of the tissue. Double mutant studies between tdy1 and chloroplast-impaired mutants demonstrate that functional chloroplasts are needed to generate the Suc that induces the tdy1 phenotype. However, we also found that albino cells can express the tdy1 phenotype and overaccumulate Suc imported from neighboring green tissues. To characterize the site and mode of action of Tdy1, we performed a clonal mosaic analysis. In the transverse dimension, we localized the function of Tdy1 to the innermost leaf layer. Additionally, we determined that if this layer lacks Tdy1, Suc can accumulate, move into adjacent genetically wild-type layers, and induce tdy1 phenotypic expression. In the lateral dimension, we observed that a tdy1 phenotypic region did not reach the mosaic sector boundary, suggesting that wild-type Tdy1 acts non-cell autonomously and exerts a short-range compensatory effect on neighboring mutant tissue. A model proposing that Tdy1 functions in the vasculature to sense high concentrations of sugar, up-regulate Suc transport into veins, and promote tissue differentiation and function is discussed.
Maize Y9 Encodes a Product Essential for 15-cis-ζ-Carotene Isomerization
Authors: Li Faqiang , Murillo Christina , Wurtzel Eleanore T. 
Published: April 2007

Abstract
Carotenoids are a diverse group of pigments found in plants, fungi, and bacteria. They serve essential functions in plants and provide health benefits for humans and animals. In plants, it was thought that conversion of the C40 carotenoid backbone, 15-cis-phytoene, to all-trans-lycopene, the geometrical isomer required by downstream enzymes, required two desaturases (phytoene desaturase and ζ-carotene desaturase [ZDS]) plus a carotene isomerase (CRTISO), in addition to light-mediated photoisomerization of the 15-cis-double bond; bacteria employ only a single enzyme, CRTI. Characterization of the maize (Zea mays) pale yellow9 (y9) locus has brought to light a new isomerase required in plant carotenoid biosynthesis. We report that maize Y9 encodes a factor required for isomerase activity upstream of CRTISO, which we term Z-ISO, an activity that catalyzes the cis- to trans-conversion of the 15-cis-bond in 9,15,9′-tri-cis-ζ-carotene, the product of phytoene desaturase, to form 9,9′-di-cis-ζ-carotene, the substrate of ZDS. We show that recessive y9 alleles condition accumulation of 9,15,9′-tri-cis-ζ-carotene in dark tissues, such as roots and etiolated leaves, in contrast to accumulation of 9,9′-di-cis-ζ-carotene in a ZDS mutant, viviparous9. We also identify a locus in Euglena gracilis, which is similarly required for Z-ISO activity. These data, taken together with the geometrical isomer substrate requirement of ZDS in evolutionarily distant plants, suggest that Z-ISO activity is not unique to maize, but will be found in all higher plants. Further analysis of this new gene-controlled step is critical to understanding regulation of this essential biosynthetic pathway.
Characterization of theVIER F-BOX PROTEINEGenes fromArabidopsisReveals Their Importance for Plant Growth and Development
Authors: Schwager Katja M. , Calderon-Villalobos Luz Irina A. , Dohmann Esther M.N. , Willige Björn C. , Knierer Stephan , Nill Carola , Schwechheimer Claus 
Published: April 2007

AbstractE3 ubiquitin ligases (E3s) target proteins for degradation by the 26S proteasome. In SKP1/CDC53/F-box protein–type E3s, substrate specificity is conferred by the interchangeable F-box protein subunit. The vast majority of the 694 F-box proteins encoded by the Arabidopsis thaliana genome remain to be understood. We characterize the VIER F-BOX PROTEINE (VFB; German for FOUR F-BOX PROTEINS) genes from Arabidopsis that belong to subfamily C of the Arabidopsis F-box protein superfamily. This subfamily also includes the F-box proteins TRANSPORT INHIBITOR RESPONSE1 (TIR1)/AUXIN SIGNALING F-BOX (AFB) proteins and EIN3 BINDING F-BOX proteins, which regulate auxin and ethylene responses, respectively. We show that loss of VFB function causes delayed plant growth and reduced lateral root formation. We find that the expression of a number of auxin-responsive genes and the activity of DR5:β-glucuronidase, a reporter for auxin reponse, are reduced in the vfb mutants. This finding correlates with an increase in the abundance of an AUXIN/INDOLE-3-ACETIC ACID repressor. However, we also find that auxin responses are not affected in the vfb mutants and that a representative VFB family member, VFB2, cannot functionally complement the tir1-1 mutant. We therefore exclude the possibility that VFBs are functional orthologs of TIR1/AFB proteins.
Functional Analysis ofd-Alanylation of Lipoteichoic Acid in the Probiotic StrainLactobacillus rhamnosusGG
Authors: Vélez Mónica Perea , Verhoeven Tine L. A. , Draing Christian , Von Aulock Sonja , Pfitzenmaier Markus , Geyer Armin , Lambrichts Ivo , Grangette Corinne , Pot Bruno , Vanderleyden Jos , De Keersmaecker Sigrid C. J. 
Published: April 2007

ABSTRACTLipoteichoic acid (LTA) is a macroamphiphile molecule which performs several functions in gram-positive bacteria, such as maintenance of cell wall homeostasis.d-Alanylation of LTA requires the proteins encoded by thedltoperon, and this process is directly related to the charge properties of this polymer strongly contributing to its function. The insertional inactivation ofdltDof the probiotic strainLactobacillus rhamnosusGG (ATCC 53103) resulted in the complete absence ofd-alanyl esters in the LTA as confirmed by nuclear magnetic resonance analysis. This was reflected in modifications of the bacterial cell surface properties. ThedltDstrain showed 2.4-fold-increased cell length, a low survival capacity in response to gastric juice challenge, an increased sensitivity to human beta-defensin-2, an increased rate of autolysis, an increased capacity to initiate growth in the presence of an anionic detergent, and a decreased capacity to initiate growth in the presence of cationic peptides compared to wild-type results. However, in vitro experiments revealed no major differences for adhesion to human intestinal epithelial cells, biofilm formation, and immunomodulation. These properties are considered to be important for probiotics. The role of thedltoperon in lactobacilli is discussed in view of these results.
Purification, Characterization, Gene Cloning, and Expression of a Novel Alcohol Dehydrogenase with Anti-Prelog Stereospecificity from
Candida parapsilosis
Authors: Nie Yao , Xu Yan , Mu Xiao Qing , Wang Hai Yan , Yang Ming , Xiao Rong 
Published: April 2007

ABSTRACT

An alcohol dehydrogenase from
Candida parapsilosis
CCTCC M203011 was characterized along with its biochemical activity and structural gene. The amino acid sequence shows similarity to those of the short-chain dehydrogenase/reductases but no overall identity to known proteins. This enzyme with unusual stereospecificity catalyzes an anti-Prelog reduction of 2-hydroxyacetophenone to (
S
)-1-phenyl-1,2-ethanediol.
Signal Mimics Derived from a Metagenomic Analysis of the Gypsy Moth Gut Microbiota
Authors: Guan Changhui , Ju Jianhua , Borlee Bradley R. , Williamson Lynn L. , Shen Ben , Raffa Kenneth F. , Handelsman Jo 
Published: April 2007

ABSTRACT

Bacterial signaling is an important part of community life, but little is known about the signal transduction pathways of the as-yet-uncultured members of microbial communities. To address this gap, we aimed to identify genes directing the synthesis of signals in uncultured bacteria associated with the midguts of gypsy moth larvae. We constructed a metagenomic library consisting of DNA extracted directly from the midgut microbiota and analyzed it using an intracellular screen designated METREX, which detects inducers of quorum sensing. In this screen, the metagenomic DNA and a biosensor reside in the same cell. The biosensor consists of a quorum-sensing promoter, which requires an acylhomoserine lactone or other small molecule ligand for activation, driving the expression of the reporter gene
gfp
. We identified an active metagenomic clone encoding a monooxygenase homologue that mediates a pathway of indole oxidation that leads to the production of a quorum-sensing inducing compound. The signal from this clone induces the activities of LuxR from
Vibrio fischeri
and CviR from
Chromobacterium violaceum
. This study is the first to identify a new structural class of quorum-sensing inducer from uncultured bacteria.
Identification of Anaerobic Selenate-Respiring Bacteria from Aquatic Sediments
Authors: Narasingarao Priya , Häggblom Max M. 
Published: April 2007

ABSTRACTThe diversity population of microorganisms with the capability to use selenate as a terminal electron acceptor, reducing it to selenite and elemental selenium by the process known as dissimilatory selenate reduction, is largely unknown. The overall objective of this study was to gain an in-depth understanding of anaerobic biotransformation of selenium in the environment, particularly anaerobic respiration, and to characterize the microorganisms catalyzing this process. Here, we demonstrate the isolation and characterization of four novel anaerobic dissimilatory selenate-respiring bacteria enriched from a variety of sources, including sediments from three different water bodies in Chennai, India, and a tidal estuary in New Jersey. Strains S5 and S7 from India, strain KM from the Meadowlands, NJ, and strain pn1, categorized as a laboratory contaminant, were all phylogenetically distinct, belonging to various phyla in the bacterial domain. The 16S rRNA gene sequence shows that strain S5 constitutes a new genus belonging toChrysiogenetes, while strain S7 belongs to theDeferribacteres, with greater than 98% 16S rRNA gene similarity toGeovibrio ferrireducens. Strain KM is related toMalonomonas rubra,Pelobacter acidigallici, andDesulfuromusaspp., with 96 to 97% 16S rRNA gene similarity. Strain pn1 is 99% similar toPseudomonas stutzeri. Strains S5, S7, and KM are obligately anaerobic selenate-respiring microorganisms, while strain pn1 is facultatively anaerobic. Besides respiring selenate, all these strains also respire nitrate.
Quorum Sensing Enhances the Stress Response in
Vibrio cholerae
Authors: Joelsson Adam , Kan Biao , Zhu Jun 
Published: April 2007

ABSTRACT

Vibrio cholerae
lives in aquatic environments and causes cholera. Here, we show that quorum sensing enhances
V. cholerae
viability under certain stress conditions by upregulating the expression of RpoS, and this regulation acts through HapR, suggesting that a quorum-sensing-enhanced stress response plays a role in
V. cholerae
environmental survival.
Kinetics and Metabolism of
Bifidobacterium adolescentis
MB 239 Growing on Glucose, Galactose, Lactose, and Galactooligosaccharides
Authors: Amaretti Alberto , Bernardi Tatiana , Tamburini Elena , Zanoni Simona , Lomma Mariella , Matteuzzi Diego , Rossi Maddalena 
Published: April 2007

ABSTRACT

The kinetics and the metabolism of
Bifidobacterium adolescentis
MB 239 growing on galactooligosaccharides (GOS), lactose, galactose, and glucose were investigated. An unstructured unsegregated model for growth in batch cultures was developed, and kinetic parameters were calculated with a recursive algorithm. The growth rate and cellular yield were highest on galactose, followed by lactose and GOS, and were lowest on glucose. Lactate, acetate, and ethanol yields allowed the calculation of carbon fluxes toward fermentation products. Distributions between two- and three-carbon products were similar on all the carbohydrates (55 and 45%, respectively), but ethanol yields were different on glucose, GOS, lactose, and galactose, in decreasing order of production. Based on the stoichiometry of the fructose-6-phosphate shunt and on the carbon distribution among the products, the ATP yield was calculated. The highest yield was obtained on galactose, while the yields were 5, 8, and 25% lower on lactose, GOS, and glucose, respectively. Therefore, a correspondence among ethanol production, low ATP yields, and low biomass production was established, demonstrating that carbohydrate preferences may result from different distributions of carbon fluxes through the fermentative pathway. During the fermentation of a GOS mixture, substrate selectivity based on the degree of polymerization was exhibited, since lactose and the trisaccharide were the first to be consumed, while a delay was observed until longer oligosaccharides were utilized. Throughout the growth on both lactose and GOS, galactose accumulated in the cultural broth, suggesting that β(1-4) galactosides can be hydrolyzed before they are taken up.
Role of Chromosomal and Plasmid-Borne Receptor Homologues in the Response of
Bacillus megaterium
QM B1551 Spores to Germinants
Authors: Christie Graham , Lowe Christopher R. 
Published: April 2007

ABSTRACT

Spores of
Bacillus megaterium
QM B1551 germinate in response to a number of trigger compounds, including glucose, proline, leucine, and inorganic salts. An approximate 6-kb region of the 165-kb plasmid was found to harbor a tricistronic receptor operon,
gerU
, and a monocistronic receptor component,
gerVB
. The
gerU
operon was observed to complement the germination response in plasmidless strain PV361 to glucose and leucine, with KBr acting as a cogerminant. Proline recognition is conferred by the monocistronic
gerVB
gene, the presence of which also improves the germination response to other single-trigger compounds. A chimeric receptor, GerU*, demonstrates interchangeability between receptor components and provides evidence that it is the B protein of the receptor that determines germinant specificity. Introduction of the
gerU
/
gerVB
gene cluster to
B. megaterium
KM extends the range of germinants recognized by this strain to include glucose, proline, and KBr in addition to alanine and leucine. A chromosomally encoded receptor, GerA, the B component of which is predicted to be truncated, was found to be functionally redundant. Similarly, the plasmid-borne antiporter gene,
grmA
, identified previously as being essential for germination in QM B1551, did not complement the germination defect in the plasmidless variant PV361. Wild-type spores carrying an insertion-deletion mutation in this cistron germinated normally; thus, the role of GrmA in spore germination needs to be reevaluated in this species.
The Complex of
Sphingomonas elodea
ATCC 31461 Glucose-1-Phosphate Uridylyltransferase with Glucose-1-Phosphate Reveals a Novel Quaternary Structure, Unique among Nucleoside Diphosphate-Sugar Pyrophosphorylase Members
Authors: Aragão David , Fialho Arsénio M. , Marques Ana R. , Mitchell Edward P. , Sá-Correia Isabel , Frazão Carlos 
Published: April 2007

ABSTRACT

Gellan gum is a widely used commercial material, available in many different forms. Its economic importance has led to studies into the biosynthesis of exopolysaccharide gellan gum, which is industrially prepared in high yields using
Sphingomonas elodea
ATCC 31461. Glucose-1-phosphate uridylyltransferase mediates the reversible conversion of glucose-1-phosphate and UTP into UDP-glucose and pyrophosphate, which is a key step in the biosynthetic pathway of gellan gums. Here we present the X-ray crystal structure of the glucose-1-phosphate uridylyltransferase from
S. elodea
. The
S. elodea
enzyme shares strong monomeric similarity with glucose-1-phosphate thymidylyltransferase, several structures of which are known, although the quaternary structures of the active enzymes are rather different. A detailed comparison between
S. elodea
glucose-1-phosphate uridylyltransferase and available thymidylyltransferases is described and shows remarkable structural similarities, despite the low sequence identities between the two divergent groups of proteins.
A Biomechanical Comparison of Initial Fixation Strength of 3 Different Methods of Anterior Cruciate Ligament Soft Tissue Graft Tibial Fixation
Authors: Bartz Reed L. , Mossoni Kory , Tyber Jeffrey , Tokish John , Gall Kenneth , Siparsky Patrick N. 
Published: April 2007

Background Tibial fixation of soft tissue grafts continues to be problematic in the early postoperative period after anterior cruciate ligament reconstruction. Hypothesis No differences exist for resistance to slippage of soft tissue grafts fixed with CentraLoc, Intrafix, or 35-mm bioabsorbable interference screws. Study Design Controlled laboratory study. Methods Bovine tibia and hoof extensor tendons were divided into 3 matched groups with 12 tibia and 12 extensor tendons in each group. Within each group, 6 specimens underwent monotonic loading to failure (1 mm/s), and 6 underwent cyclic loading (10 000 cycles, 125-325 N, 1 Hz). Results No statistically significant differences were noted in mean load to failure or stiffness. The mean load to failure (and stiffness) for the 3 types of fixation were as follows: bioabsorbable interference screw, 631.6 ± 130.1 N (88.17 ± 6.79 N/mm); Intrafix, 644.3 ± 195.2 N (81.65 ± 16.5 N/mm); and CentraLoc, 791.1 ± 72.7 N (77.89 ± 7.07 N/mm). The slippage rates under cyclic loading for the 3 types of fixation were bioabsorbable interference screw, 0.336 ± 0.074 µm/cycle; Intrafix, 27.2 ± 31.6 µm/cycle; and CentraLoc, 0.0355 ± 0.0046 µm/cycle. In this model, CentraLoc proved statistically superior in resistance to cyclic loading compared with the bioabsorbable interference screw (P < .05) and Intrafix (P < .0001). The bioabsorbable interference screw proved statistically superior to Intrafix in resistance to cyclic loading (P < .05). Conclusions In this bovine model, CentraLoc and bioabsorbable interference screws provided superior resistance to cyclic loading compared with Intrafix. Clinical Relevance CentraLoc and bioabsorbable interference screws showed superior resistance to cyclic loading, which may indicate an increased resistance to clinical failure.
X-linked clonality testing: interpretation and limitations
Authors: Chen George L. , Prchal Josef T. 
Published: April 2007

AbstractClonality often defines the diseased state in hematology. Clonal cells are genetically homogenous and derived from the same precursor; their detection is based on genotype or phenotype. Genotypic clonality relies on somatic mutations to mark the clonal population. Phenotypic clonality identifies the clonal population by the expression pattern of surrogate genes that track the clonal process. The most commonly used phenotypic clonality methods are based on the X-chromosome inactivation principle. Clonality detection based on X-chromosome inactivation patterns (XCIP) requires discrimination of the active from the inactive X chromosome and differentiation of each X chromosome's parental origin. Detection methods are based on detection of X-chromosome sequence polymorphisms identified by protein isoforms, transcribed mRNA, and methylation status. Errors in interpreting clonality tests arise from stochastic, genetic, and cell selection pressures on the mechanism of X inactivation. Progressive X-chromosome skewing has recently been suggested by XCIP clonality studies in aging hematopoietic cells. This has led to new insights into the pathophysiology of X-linked and autoimmune disorders. Other research applications include combining XCIP clonality testing with genetic clonality testing to identify clonal populations with yet-to-be-discovered genetic changes.
Reversal of autoimmune disease in lupus-prone New Zealand black/New Zealand white mice by nonmyeloablative transplantation of purified allogeneic hematopoietic stem cells
Authors: Smith-Berdan Stephanie , Gille Daphne , Weissman Irving L. , Christensen Julie L. 
Published: April 2007

AbstractPatients with severe systemic lupus erythematosus (SLE) refractory to conventional treatment are candidates for autologous hematopoietic stem cell (HSC) transplantation if the intent is to reset the immunologic clock. These patients might be candidates for allotransplantation with (SLE)-resistant major histocompatibility complex (MHC) haplotype-matched HSC if partial or complete replacement of an autoimmune-prone system is the intent. Using lupus-prone New Zealand black × New Zealand white (NZBW) mice, we investigated the use of highly enriched, haplomismatched, allogeneic HSC to prevent development of or to treat established autoimmune pathology. Young NZBW mice receiving purified allogeneic HSC transplants had improved survival, decreased proteinuria, circulating immune complexes, and autoantibodies to nuclear antigens than did untreated mice or mice given NZBW HSCs. NZBW mice with established lupus-like disease that received nonmyeloablative conditioning and transplants of (MHC) haplomismatched allogeneic HSCs also had greatly increased overall survival. Mice that received transplants exhibited stabilization or reversal of their lupus symptoms; stabilized or decreased proteinuria, and a lower frequency of elevated circulating immune complexes or autoantibodies than did control mice. Induction of durable mixed chimerism by transplantation of purified allogeneic HSCs after nonmyeloablative conditioning has the potential to reverse symptoms of established NZBW lupus.
Attachment styles, earlier interpersonal relationships and schizotypy in a non‐clinical sample
Authors: Berry Katherine , Band Rebecca , Corcoran Rhiannon , Barrowclough Christine , Wearden Alison 
Published: April 2007

Objectives. This paper investigates associations between adult attachment style, relationships with significant others during childhood, traumatic life‐events and schizotypy.Design. Relationships between attachment and hypothesized correlates were investigated in a cross‐sectional design using an analogue sample. The reliability of the attachment and trauma measures was investigated using a test‐retest design.Methods. Three hundred and four students completed the self‐report version of the Psychosis Attachment Measure (PAM), maternal and paternal versions of the Parental Bonding Instrument, the Attachment History Questionnaire, a measure of trauma and the Oxford‐Liverpool Inventory of Feelings and Experiences scale through an internet website.Results. As predicted, there were statistically significant associations between insecure attachment in adult relationships and experiences of negative interpersonal events. Both earlier interpersonal experiences and adult attachment style predicted schizotypy, and adult attachment style emerged as an independent predictor of positive schizotypal characteristics.Conclusions. The findings support associations between adult attachment style and previous interpersonal experiences and between adult attachment and schizotypy. The PAM is a reliable and valid instrument that can be used to explore attachment styles in analogue samples and associations between attachment styles and psychotic symptoms in clinical samples.