bluuebunny/crossref_metadata_2025_split huggingface dataset:
Repressing the Expression of the SUCROSE NONFERMENTING-1-RELATED PROTEIN KINASE Gene in Pea Embryo Causes Pleiotropic Defects of Maturation Similar to an Abscisic Acid-Insensitive Phenotype
Authors: Radchuk Ruslana , Radchuk Volodymyr , Weschke Winfriede , Borisjuk Ljudmilla , Weber Hans 
Published: December 2005

Abstract
The classic role of SUCROSE NONFERMENTING-1 (Snf1)-like kinases in eukaryotes is to adapt metabolism to environmental conditions such as nutrition, energy, and stress. During pea (Pisum sativum) seed maturation, developmental programs of growing embryos are adjusted to changing physiological and metabolic conditions. To understand regulation of the switch from cell proliferation to differentiation, SUCROSE NONFERMENTING-1-RELATED PROTEIN KINASE (SnRK1) was antisense repressed in pea seeds. Transgenic seeds show maturation defects, reduced conversion of sucrose into storage products, lower globulin content, frequently altered cotyledon surface, shape, and symmetry, as well as occasional precocious germination. Gene expression analysis of embryos using macroarrays of 5,548 seed-specific genes revealed 183 differentially expressed genes in two clusters, either delayed down-regulated or delayed up-regulated during transition. Delayed down-regulated genes are related to mitotic activity, gibberellic acid/brassinosteroid synthesis, stress response, and Ca2+ signal transduction. This specifies a developmentally younger status and conditional stress. Higher gene expression related to respiration/gluconeogenesis/fermentation is consistent with a role of SnRK1 in repressing energy-consuming processes in maturing cotyledons under low oxygen/energy availability. Delayed up-regulated genes are mainly related to storage protein synthesis and stress tolerance. Most of the phenotype resembles abscisic acid (ABA) insensitivity and may be explained by reduced Abi-3 expression. This may cause a reduction in ABA functions and/or a disconnection between metabolic and ABA signals, suggesting that SnRK1 is a mediator of ABA functions during pea seed maturation. SnRK1 repression also impairs gene expression associated with differentiation, independent from ABA functions, like regulation and signaling of developmental events, chromatin reorganization, cell wall synthesis, biosynthetic activity of plastids, and regulated proteolysis.
Distinct Roles of the First Introns on the Expression of Arabidopsis Profilin Gene Family Members
Authors: Jeong Young-Min , Mun Jeong-Hwan , Lee Ilha , Woo Je Chang , Hong Choo Bong , Kim Sang-Gu 
Published: December 2005

Abstract
Profilin is a small actin-binding protein that regulates cellular dynamics of the actin cytoskeleton. In Arabidopsis (Arabidopsis thaliana), five profilins were identified. The vegetative class profilins, PRF1, PRF2, and PRF3, are expressed in vegetative organs. The reproductive class profilins, PRF4 and PRF5, are mainly expressed in pollen. In this study, we examined the role of the first intron in the expression of the Arabidopsis profilin gene family using transgenic plants and a transient expression system. In transgenic plants, we examined PRF2 and PRF5, which represent vegetative and reproductive profilins. The expression of the PRF2 promoter fused with the β-glucuronidase (GUS) gene was observed in the vascular bundles, but transgenic plants carrying the PRF2 promoter-GUS with its first intron showed constitutive expression throughout the vegetative tissues. However, the first intron of PRF5 had little effect on the reporter gene expression pattern. Transgenic plants containing PRF5 promoter-GUS fusion with or without its first intron showed reproductive tissue-specific expression. To further investigate the different roles of the first two introns on gene expression, the first introns were exchanged between PRF2 and PRF5. The first intron of PRF5 had no apparent effect on the expression pattern of the PRF2 promoter. But, unlike the intron of PRF5, the first intron of PRF2 greatly affected the reproductive tissue-specific expression of the PRF5 promoter, confirming a different role for these introns. The results of a transient expression assay indicated that the first intron of PRF1 and PRF2 enhances gene expression, whereas PRF4 and PRF5 do not. These results suggest that the first introns of profilin genes are functionally distinctive and the first introns are required for the strong and constitutive gene expression of PRF1 and PRF2 in vegetative tissues.
Overexpression of RAN1 in Rice and Arabidopsis Alters Primordial Meristem, Mitotic Progress, and Sensitivity to Auxin
Authors: Wang Xin , Xu Yunyuan , Han Ye , Bao Shilai , Du Jizhou , Yuan Ming , Xu Zhihong , Chong Kang 
Published: December 2005

Abstract
Ran is an evolutionarily conserved eukaryotic GTPase. We previously identified a cDNA of TaRAN1, a novel Ran GTPase homologous gene in wheat (Triticum aestivum) and demonstrated that TaRAN1 is associated with regulation of genome integrity and cell division in yeast (Saccharomyces cerevisiae) systems. However, much less is known about the function of RAN in plant development. To analyze the possible biological roles of Ran GTPase, we overexpressed TaRAN1 in transgenic Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa). TaRAN1 overexpression increased the proportion of cells in the G2 phase of the cell cycle, which resulted in an elevated mitotic index and prolonged life cycle. Furthermore, it led to increased primordial tissue, reduced number of lateral roots, and stimulated hypersensitivity to exogenous auxin. The results suggest that Ran protein was involved in the regulation of mitotic progress, either in the shoot apical meristem or the root meristem zone in plants, where auxin signaling is involved. This article determines the function of RAN in plant development mediated by the cell cycle and its novel role in meristem initiation mediated by auxin signaling.
An ll-Diaminopimelate Aminotransferase Defines a Novel Variant of the Lysine Biosynthesis Pathway in Plants
Authors: Hudson André O. , Singh Bijay K. , Leustek Thomas , Gilvarg Charles 
Published: December 2005

Abstract
Although lysine (Lys) biosynthesis in plants is known to occur by way of a pathway that utilizes diaminopimelic acid (DAP) as a central intermediate, the available evidence suggests that none of the known DAP-pathway variants found in nature occur in plants. A new Lys biosynthesis pathway has been identified in Arabidopsis (Arabidopsis thaliana) that utilizes a novel transaminase that specifically catalyzes the interconversion of tetrahydrodipicolinate and ll-diaminopimelate, a reaction requiring three enzymes in the DAP-pathway variant found in Escherichia coli. The ll-DAP aminotransferase encoded by locus At4g33680 was able to complement the dapD and dapE mutants of E. coli. This result, in conjunction with the kinetic properties and substrate specificity of the enzyme, indicated that ll-DAP aminotransferase functions in the Lys biosynthetic direction under in vivo conditions. Orthologs of At4g33680 were identified in all the cyanobacterial species whose genomes have been sequenced. The Synechocystis sp. ortholog encoded by locus sll0480 showed the same functional properties as At4g33680. These results demonstrate that the Lys biosynthesis pathway in plants and cyanobacteria is distinct from the pathways that have so far been defined in microorganisms.
The Arabidopsis Group 1 LATE EMBRYOGENESIS ABUNDANT Protein ATEM6 Is Required for Normal Seed Development
Authors: Manfre Alicia J. , Lanni Lea M. , Marcotte William R. 
Published: December 2005

Abstract
As part of the embryo maturation process, orthodox seeds undergo a developmentally regulated dehydration period. The LATE EMBRYOGENESIS ABUNDANT (LEA) genes encode a large and diverse family of proteins expressed during this time. Many hypothesize that LEA proteins act by mitigating water loss and maintaining cellular stability within the desiccated seed, although the mechanisms of their actions remain largely unknown. The model plant Arabidopsis (Arabidopsis thaliana) contains two genes belonging to the group 1 LEA family, ATEM1 and ATEM6, and knockout mutations in these genes are being sought as a means to better understand group 1 LEA protein function during embryo maturation. We have identified a T-DNA insertion allele of the ATEM6 gene in which the T-DNA is present just downstream of the protein coding region. While this gene is transcriptionally active and encodes a wild-type protein, there is no detectable ATEM6 protein in mature seeds. Mutant seeds display premature seed dehydration and maturation at the distal end of siliques, demonstrating that this protein is required for normal seed development. We propose that one function for group 1 LEA proteins in seed development is to buffer the water loss that occurs during embryo maturation and that loss of ATEM6 expression results in the mutant phenotype.
Different Domains Control the Localization and Mobility of LIKE HETEROCHROMATIN PROTEIN1 inArabidopsisNuclei
Authors: Zemach Assaf , Li Yan , Ben-Meir Hagit , Oliva Moran , Mosquna Assaf , Kiss Vladimir , Avivi Yigal , Ohad Nir , Grafi Gideon 
Published: December 2005

AbstractPlants possess a single gene for the structurally related HETEROCHROMATIN PROTEIN1 (HP1), termed LIKE-HP1 (LHP1). We investigated the subnuclear localization, binding properties, and dynamics of LHP1 proteins in Arabidopsis thaliana cells. Transient expression assays showed that tomato (Solanum lycopersicum) LHP1 fused to green fluorescent protein (GFP; Sl LHP1-GFP) and Arabidopsis LHP1 (At LHP1-GFP) localized to heterochromatic chromocenters and showed punctuated distribution within the nucleus; tomato but not Arabidopsis LHP1 was also localized within the nucleolus. Mutations of aromatic cage residues that recognize methyl K9 of histone H3 abolished their punctuated distribution and localization to chromocenters. Sl LHP1-GFP plants displayed cell type–dependent subnuclear localization. The diverse localization pattern of tomato LHP1 did not require the chromo shadow domain (CSD), whereas the chromodomain alone was insufficient for localization to chromocenters; a nucleolar localization signal was identified within the hinge region. Fluorescence recovery after photobleaching showed that Sl LHP1 is a highly mobile protein whose localization and retention are controlled by distinct domains; retention at the nucleolus and chromocenters is conferred by the CSD. Our results imply that LHP1 recruitment to chromatin is mediated, at least in part, through interaction with methyl K9 and that LHP1 controls different nuclear processes via transient binding to its nuclear sites.
TheArabidopsis vitamin E pathway gene5-1Mutant Reveals a Critical Role for Phytol Kinase in Seed Tocopherol Biosynthesis
Authors: Valentin Henry E. , Lincoln Kim , Moshiri Farhad , Jensen Pamela K. , Qi Qungang , Venkatesh Tyamagondlu V. , Karunanandaa Balasulojini , Baszis Susan R. , Norris Susan R. , Savidge Beth , Gruys Kenneth J. , Last Robert L. 
Published: December 2005

AbstractWe report the identification and characterization of a low tocopherol Arabidopsis thaliana mutant, vitamin E pathway gene5-1 (vte5-1), with seed tocopherol levels reduced to 20% of the wild type. Map-based identification of the responsible mutation identified a G→A transition, resulting in the introduction of a stop codon in At5g04490, a previously unannotated gene, which we named VTE5. Complementation of the mutation with the wild-type transgene largely restored the wild-type tocopherol phenotype. A knockout mutation of the Synechocystis sp PCC 6803 VTE5 homolog slr1652 reduced Synechocystis tocopherol levels by 50% or more. Bioinformatic analysis of VTE5 and slr1652 indicated modest similarity to dolichol kinase. Analysis of extracts from Arabidopsis and Synechocystis mutants revealed increased accumulation of free phytol. Heterologous expression of these genes in Escherichia coli supplemented with free phytol and in vitro assays of recombinant protein produced phytylmonophosphate, suggesting that VTE5 and slr1652 encode phytol kinases. The phenotype of the vte5-1 mutant is consistent with the hypothesis that chlorophyll degradation-derived phytol serves as an important intermediate in seed tocopherol synthesis and forces reevaluation of the role of geranylgeranyl diphosphate reductase in tocopherol biosynthesis.
ArabidopsisCytokinin Receptor Mutants Reveal Functions in Shoot Growth, Leaf Senescence, Seed Size, Germination, Root Development, and Cytokinin Metabolism
Authors: Riefler Michael , Novak Ondrej , Strnad Miroslav , Schmülling Thomas 
Published: December 2005

AbstractWe used loss-of-function mutants to study three Arabidopsis thaliana sensor histidine kinases, AHK2, AHK3, and CRE1/AHK4, known to be cytokinin receptors. Mutant seeds had more rapid germination, reduced requirement for light, and decreased far-red light sensitivity, unraveling cytokinin functions in seed germination control. Triple mutant seeds were more than twice as large as wild-type seeds. Genetic analysis indicated a cytokinin-dependent endospermal and/or maternal control of embryo size. Unchanged red light sensitivity of mutant hypocotyl elongation suggests that previously reported modulation of red light signaling by A-type response regulators may not depend on cytokinin. Combined loss of AHK2 and AHK3 led to the most prominent changes during vegetative development. Leaves of ahk2 ahk3 mutants formed fewer cells, had reduced chlorophyll content, and lacked the cytokinin-dependent inhibition of dark-induced chlorophyll loss, indicating a prominent role of AHK2 and, particularly, AHK3 in the control of leaf development. ahk2 ahk3 double mutants developed a strongly enhanced root system through faster growth of the primary root and, more importantly, increased branching. This result supports a negative regulatory role for cytokinin in root growth regulation. Increased cytokinin content of receptor mutants indicates a homeostatic control of steady state cytokinin levels through signaling. Together, the analyses reveal partially redundant functions of the cytokinin receptors and prominent roles for the AHK2/AHK3 receptor combination in quantitative control of organ growth in plants, with opposite regulatory functions in roots and shoots.
Stability, sensitivity, science and heurism
Authors: Grant Taran , Kluge Arnold G. 
Published: December 2005

AbstractWe examine recently proposed justifications of sensitivity analysis sensuWheeler (1995), here referred to as weighted‐classes sensitivity analysis (WCSA). We refute Giribet's (2003a) claim that WCSA is the strictest possible test for a given phylogenetic hypothesis. Giribet's (2003a) classification of data exploration methods as evaluating “nodal stability” or “nodal support” is arbitrary, at odds with common usage and actually obscures the relationships between the methods he examined, all of which seek to assess the sensitivity of results to variation in analytical conditions. Stability, whether statistical or taxonomic, is not a goal of phylogenetic science. Statistical stability necessarily involves trial repetition, which is impossible in ideographic sciences like phylogenetics. Taxonomic stability can be nothing more than an unintended by‐product of scientific inquiry, i.e., the repeated failure to refute a hypothesis. Schulmeister's (2003) “robust‐choice” defense of WCSA does not succeed in placing non‐arbitrary bounds on parameters, and her interpretation of this approach as simultaneously verificationist and falsificationist is logically inconsistent. WCSA is neither scientific nor heuristic and therefore does not contribute to the advancement of objective knowledge claims.© The Willi Hennig Society 2005.
Pharmacokinetics of a new testosterone transdermal delivery system, TDS®‐testosterone in healthy males
Authors: Chik Z. , Johnston A. , Tucker A. T. , Chew S. L. , Michaels L. , Alam C. A. S. 
Published: December 2005

AimsThe Transdermal Delivery System (TDS®) is a liquid formulation that can be applied to the skin via a metered pump spray to deliver drug to the systemic circulation. The aims of this study were to assess the ability of the TDS® preparation to deliver testosterone systemically, and to characterize the pharmacokinetic profiles of the hormone in healthy males.MethodsAn open label, comparative, randomized placebo controlled study involving three treatments and three periods with a minimum of a 1 week washout period was conducted. Twelve healthy males received 50 mg TDS®‐testosterone, TDS®‐placebo, and 50 mg of a commercially available topical testosterone preparation (Androgel®, 1% topical testosterone gel).ResultsThe mean AUC(0,12 h) was higher following application of TDS®‐testosterone (61.8 ng ml−1 h), compared with Androgel® (57.7 ng ml−1 h) and TDS®‐placebo (50.7 ng ml−1 h. The mean Cmax (0,12 h) was similar for TDS®‐testosterone (6.6 ng ml−1) and Androgel® (6.5 ng ml−1) and these values were higher than those for TDS®‐placebo (5.7 ng ml−1). Analysis of variance showed that the 90% confidence intervals on the relative difference of the ratio for the AUC(0,12 h) and the Cmax (0,12 h) between TDS®‐testosterone and Androgel®, were contained within the bioequivalence limit (80, 125%) (Cmax 89.2, 112.3% and AUC 93.5, 120.5%). Serum testosterone concentrations were lower following TDS®‐Placebo and were not bioequivalent either to the gel or spray.ConclusionsThe TDS® preparation was shown to deliver testosterone systemically to humans and the concentrations of the hormone in the 12 h following TDS® administration were bioequivalent to an existing topical delivery gel.
Comparative effects of ivabradine, a selective heart rate‐lowering agent, and propranolol on systemic and cardiac haemodynamics at rest and during exercise
Authors: Joannides Robinson , Moore Nicholas , Iacob Michaela , Compagnon Patricia , Lerebours Guy , Menard Jean‐François , Thuillez Christian 
Published: December 2005

AimTo compare in humans the effects of ivabradine and propranolol on cardiac and systemic haemodynamics at rest, during tilt and exercise.MethodsNine healthy volunteers randomly received single oral doses of ivabradine (Iva, 30 mg), propranolol (Propra, 40 mg) or placebo (Plac) during a double‐blind cross‐over study. Doses were selected to be equipotent in heart rate (HR) reduction. HR, systolic and diastolic blood pressure (SBP, DBP), cardiac index (CI, bioimpedance), rate pressure product (RPP), plasma epinephrine (E) and norepinephrine (NE), were measured at rest at baseline, before and after two tilt and exercise tests, started 2 and 5 h after drug intake. Heart rate variability (low to high frequency ratio LF/HF) was evaluated at rest and at 5th minute of tilt.ResultsAt rest, HR and RPP decreased similarly with Iva and Propra (both P < 0.01). During tilt, HR increased less with Iva than Propra (P < 0.01), LF/HF decreased after Iva (P < 0.03), SBP and mean blood pressure decreased after Propra (both P < 0.01), RPP decreased similarly after Iva and Propra (both P < 0.01) and CI decreased to a greater exent with Propra than with Iva or Plac (both P < 0.04). During exercise, Iva and Propra similarly decreased HR (both P < 0.01) and RPP (P < 0.01).ConclusionsThese results demonstrate that for a similar decrease in HR at rest and during sympathetic stimulation, acute administration of ivabradine, a selective heart rate‐lowering agent, decreased myocardial oxygen demand to the same extent as a reference β‐blocker, propranolol, but without evidence of depressant effect on cardiac function.
Enantioselective disposition of rabeprazole in relation to CYP2C19 genotypes
Authors: Miura Masatomo , Kagaya Hideaki , Tada Hitoshi , Uno Tsukasa , Yasui‐Furukori Norio , Tateishi Tomonori , Suzuki Toshio 
Published: December 2005

AimRabeprazole is metabolized to some extent by CYP2C19. The purpose of this study was to elucidate the pharmacokinetics of each rabeprazole enantiomer in three different CYP2C19 genotype groups.MethodsTwenty‐four healthy subjects, of whom each each were homozygous extensive metabolizers (homEMs), heterozygous extensive metabolizers (hetEMs) and poor metabolizers (PMs) for CYP2C19, participated in our study. After a single oral dose of 20 mg of racemic rabeprazole, the plasma concentrations of the rabeprazole enantiomers were measured over the course of 24 h.ResultsThe area under the plasma concentration–time curves (AUC) of (R)‐rabeprazole in homEMs, hetEMs and PMs were 1.8‐, 2.2‐ and 2.4‐fold, respectively, greater than those of (S)‐rabeprazole; the relative AUC ratios of (R)‐ and (S)‐rabeprazole in homEMs, hetEMs and PMs were 1 : 1.1 : 2.1 and 1 : 0.9 : 1.5, respectively. The mean maximum plasma concentrations (Cmax) of (R)‐rabeprazole in homEMs, hetEMs and PMs were 1.7‐, 1.9‐ and 1.8‐fold higher, respectively, than those of the corresponding (S)‐enantiomer (P < 0.05). There was no difference between homEMs and PMs in the elimination half‐life of (S)‐rabeprazole, whereas the elimination half‐life of (R)‐rabeprazole was significantly longer in PMs than in homEMs [1.7 h (1.4, 2.0) (mean (95% confidence interval)]vs. 0.8 h (0.6, 1.0), respectively, P < 0.0001).Conclusions(R)‐Rabeprazole disposition was influenced to a greater degree by CYP2C19 genetic polymorphisms than was that of (S)‐rabeprazole. The effect of CYP2C19 polymorphisms on the stereoselective disposition of rabeprazole was less than those of lansoprazole and omeprazole.
Histamine increases sickle erythrocyte adherence to endothelium
Authors: Wagner Matthew C. , Eckman James R. , Wick Timothy M. 
Published: December 2005

SummaryComplications of sickle cell anaemia include vascular occlusion triggered by the adherence of sickle erythrocytes to endothelium in the postcapillary venules. Adherence can be promoted by inflammatory mediators that induce endothelial cell adhesion molecule expression and arrest flowing erythrocytes. The present study characterised the effect of histamine stimulation on the kinetics of sickle cell adherence to large vessel and microvascular endothelium under physiological flow. Increased sickle cell adherence was observed within minutes of endothelial activation by histamine and reached a maximum value within 30 min. At steady state, sickle cell adherence to histamine‐stimulated endothelium was 47 ± 4 adherent cells/mm2, 2·6‐fold higher than sickle cell adherence to unstimulated endothelial cells. Histamine‐induced sickle cell adherence occurred rapidly and transiently. Studies using histamine receptor agonists and antagonists suggest that histamine‐induced sickle cell adhesion depends on simultaneous stimulation of the H2and H4histamine receptors and endothelial P‐selectin expression. These data show that histamine release may promote sickle cell adherence and vaso‐occlusion.In vivohistamine release should be studied to determine its role in sickle complications and whether blocking of specific histamine receptors may prevent clinical complications or adverse effects from histamine release stimulated by opiate analgesic treatment.