bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maize cDNAs Expressed in Endosperm Encode Functional Farnesyl Diphosphate Synthase with Geranylgeranyl Diphosphate Synthase Activity
Authors: Cervantes-Cervantes Miguel , Gallagher Cynthia E. , Zhu Changfu , Wurtzel Eleanore T. 
Published: April 2006

Abstract
Isoprenoids are the most diverse and abundant group of natural products. In plants, farnesyl diphosphate (FPP) and geranylgeranyl diphosphate (GGPP) are precursors to many isoprenoids having essential functions. Terpenoids and sterols are derived from FPP, whereas gibberellins, carotenoids, casbenes, taxenes, and others originate from GGPP. The corresponding synthases (FPP synthase [FPPS] and GGPP synthase [GGPPS]) catalyze, respectively, the addition of two and three isopentenyl diphosphate molecules to dimethylallyl diphosphate. Maize (Zea mays L. cv B73) endosperm cDNAs encoding isoprenoid synthases were isolated by functional complementation of Escherichia coli cells carrying a bacterial gene cluster encoding all pathway enzymes needed for carotenoid biosynthesis, except for GGPPS. This approach indicated that the maize gene products were functional GGPPS enzymes. Yet, the predicted enzyme sequences revealed FPPS motifs and homology with FPPS enzymes. In vitro assays demonstrated that indeed these maize enzymes produced both FPP and GGPP and that the N-terminal sequence affected the ratio of FPP to GGPP. Their functionality in E. coli demonstrated that these maize enzymes can be coupled with a metabolon to provide isoprenoid substrates for pathway use, and suggests that enzyme bifunctionality can be harnessed. The maize cDNAs are encoded by a small gene family whose transcripts are prevalent in endosperm beginning mid development. These maize cDNAs will be valuable tools for assessing the critical structural properties determining prenyl transferase specificity and in metabolic engineering of isoprenoid pathways, especially in cereal crops.
G-Protein Complex Mutants Are Hypersensitive to Abscisic Acid Regulation of Germination and Postgermination Development
Authors: Pandey Sona , Chen Jin-Gui , Jones Alan M. , Assmann Sarah M. 
Published: April 2006

AbstractAbscisic acid (ABA) plays regulatory roles in a host of physiological processes throughout plant growth and development. Seed germination, early seedling development, stomatal guard cell functions, and acclimation to adverse environmental conditions are key processes regulated by ABA. Recent evidence suggests that signaling processes in both seeds and guard cells involve heterotrimeric G proteins. To assess new roles for the Arabidopsis (Arabidopsis thaliana) Gα subunit (GPA1), the Gβ subunit (AGB1), and the candidate G-protein-coupled receptor (GCR1) in ABA signaling during germination and early seedling development, we utilized knockout mutants lacking one or more of these components. Our data show that GPA1, AGB1, and GCR1 each negatively regulates ABA signaling in seed germination and early seedling development. Plants lacking AGB1 have greater ABA hypersensitivity than plants lacking GPA1, suggesting that AGB1 is the predominant regulator of ABA signaling and that GPA1 affects the efficacy of AGB1 execution. GCR1 acts upstream of GPA1 and AGB1 for ABA signaling pathways during germination and early seedling development: gcr1 gpa1 double mutants exhibit a gpa1 phenotype and agb1 gcr1 and agb1 gcr1 gpa1 mutants exhibit an agb1 phenotype. Contrary to the scenario in guard cells, where GCR1 and GPA1 have opposite effects on ABA signaling during stomatal opening, GCR1 acts in concert with GPA1 and AGB1 in ABA signaling during germination and early seedling development. Thus, cell- and tissue-specific functional interaction in response to a given signal such as ABA may determine the distinct pathways regulated by the individual members of the G-protein complex.
Plant Retromer, Localized to the Prevacuolar Compartment and Microvesicles inArabidopsis, May Interact with Vacuolar Sorting Receptors
Authors: Oliviusson Peter , Heinzerling Oliver , Hillmer Stefan , Hinz Giselbert , Tse Yu Chung , Jiang Liwen , Robinson David G. 
Published: April 2006

AbstractReceptors for acid hydrolases destined for the lytic compartment in yeast and mammalian cells are retrieved from intermediate, endosomal organelles with the help of a pentameric protein complex called the retromer. We cloned the Arabidopsis thaliana homologs of the three yeast proteins (Vps35, Vps29, and Vps26) constituting the larger subunit of retromer and prepared antisera against them. With these antibodies, we demonstrated the presence of a retromer-like protein complex in salt extracts prepared from Arabidopsis microsomes. This complex is associated with membranes that coequilibrate with prevacuolar compartment markers and with high-density sedimenting membranes. Immunogold negative staining identified these membranes as 90-nm-diameter coated microvesicles. Confocal laser scanning immunofluorescence studies performed on tobacco (Nicotiana tabacum) BY-2 cells revealed high degrees of colabeling between all three retromer antisera and the prevacuolar compartment (PVC) markers PEP12 and vacuolar sorting receptor VSRAt-1. The presence of plant retromer at the surface of multivesicular bodies was also demonstrated by immunogold labeling of sections obtained from high-pressure frozen/freeze-substituted specimens. Treatment of BY-2 cells with wortmannin led to swelling of the PVC and a separation of the VPS35 and VSR signals. Preliminary data suggesting that retromer interacts with the cytosolic domain of a VSR were obtained by immunoprecipitation experiments performed on detergent-solubilized microsomes with Vps35 antibodies.
The Plastid Protein THYLAKOID FORMATION1 and the Plasma Membrane G-Protein GPA1 Interact in a Novel Sugar-Signaling Mechanism inArabidopsis
Authors: Huang Jirong , Taylor J. Philip , Chen Jin-Gui , Uhrig Joachim F. , Schnell Danny J. , Nakagawa Tsuyoshi , Korth Kenneth L. , Jones Alan M. 
Published: April 2006

AbstractMutations in genes encoding components of the heterotrimeric G-protein complex were previously shown to confer altered sensitivity to increased levels of d-glucose. This suggests that G-protein coupling may be a novel sugar-signaling mechanism in Arabidopsis thaliana. THYLAKOID FORMATION1 (THF1) is here demonstrated in vivo as a Gα interaction partner that functions downstream of the plasma membrane–delimited heterotrimeric G-protein (GPA1) in a d-glucose signaling pathway. THF1 is a plastid protein localized to both the outer plastid membrane and the stroma. Contact between root plastidic THF1 and GPA1 at the plasma membrane occurs at sites where the plastid membrane abuts the plasma membrane, as demonstrated by Förster resonance energy transfer (FRET). A probable role for THF1 in sugar signaling is demonstrated by both biochemical and genetic evidence. Root growth in the thf1-1 null mutant is hypersensitive to exogenous d-glucose, and THF1-overexpressing roots are resistant to inhibition of growth rate by high d-glucose. Additionally, THF1 levels are rapidly degraded by d-glucose but not l-glucose. The interaction between THF1 and GPA1 has been confirmed by in vitro and in vivo coimmunoprecipitation, FRET analysis, and genetic epistasis and provides evidence of a sugar-signaling mechanism between plastids and the plasma membrane.
Locus-Specific Control of DNA Methylation by theArabidopsisSUVH5 Histone Methyltransferase
Authors: Ebbs Michelle L. , Bender Judith 
Published: April 2006

AbstractIn Arabidopsis thaliana, heterochromatin formation is guided by double-stranded RNA (dsRNA), which triggers methylation of histone H3 at Lys-9 (H3 mK9) and CG plus non-CG methylation on identical DNA sequences. At heterochromatin targets including transposons and centromere repeats, H3 mK9 mediated by the Su(var)3-9 homologue 4 (SUVH4)/KYP histone methyltransferase (MTase) is required for the maintenance of non-CG methylation by the CMT3 DNA MTase. Here, we show that although SUVH4 is the major H3 K9 MTase, the SUVH5 protein also has histone MTase activity in vitro and contributes to the maintenance of H3 mK9 and CMT3-mediated non-CG methylation in vivo. Strikingly, the relative contributions of SUVH4, SUVH5, and a third related histone MTase, SUVH6, to non-CG methylation are locus-specific. For example, SUVH4 and SUVH5 together control transposon sequences with only a minor contribution from SUVH6, whereas SUVH4 and SUVH6 together control a transcribed inverted repeat source of dsRNA with only a minor contribution from SUVH5. This locus-specific variation suggests different mechanisms for recruiting or activating SUVH enzymes at different heterochromatic sequences. The suvh4 suvh5 suvh6 triple mutant loses both monomethyl and dimethyl H3 K9 at target loci. The suvh4 suvh5 suvh6 mutant also displays a loss of non-CG methylation similar to a cmt3 mutant, indicating that SUVH4, SUVH5, and SUVH6 together control CMT3 activity.
Evaluation of the epidermal refractive index measured by optical coherence tomography
Authors: Sand M. , Gambichler T. , Moussa G. , Bechara F. G. , Sand D. , Altmeyer P. , Hoffmann K. 
Published: April 2006

Background/aims: It has recently been proposed that the refractive index (RI) measured by means of optical coherence tomography (OCT) may be a valid measure for hydration of skin. In this pilot study, using OCT in vivo, we aimed to investigate the interday variability of RI measurements and acute changes of RI following the application of a moisturizer.Methods: Twenty healthy Caucasian volunteers were investigated on their forearms using a commercially available OCT system (SkinDex 300®, ISIS optronics GmbH, Mannheim, Germany) fitted with an integrated algorithm for the evaluation of the RI. The interday repeatability of the OCT method was determined performing symmetrical measurements on both forearms on day 1, 5, 9, and 13. In order to investigate the acute effect of a moisturizer on RI, OCT assessments were performed before and 10 min after the application of an aqueous lotion with a lipophilic phase. As a control, the contralateral site was investigated in the same way, except for the use of distilled water instead of the lotion.Results: Assessments of interday variability revealed insignificant (P>0.05) variances between the four measurement times as expressed in very small repeatability coefficients (right arm: 0.039; left arm 0.053) and small coefficients of variance (right arm: 1.02%; left arm: 1.38%). With regard to the RIs measured over time, we could not observe significant (P>0.05) differences between the two symmetrical anatomic sites (mean±SD of RI: 1.3893±0.0142 (right arm); 1.3875±0.0192 (left arm)). The acute effect of the moisturizer was indicated by a significant decrease of the RI 5 min after the application of the lotion (1.399±0.01 vs. 1.387±0.02; difference between means: 0.012; P=0.033; 95% confidence interval: 0.001–0.0023). However the control site treated with distilled water did not show significant differences between the two measurement times (1.387±0.013 vs. 1.391±0.023; difference between means: −0.004; P=0.57; 95% confidence interval: −0.019–0.011).Conclusions: In this pilot study, we have demonstrated that RI evaluation via OCT is a promising technique that may be used for the assessment of skin hydration in vivo. However, the direct comparison of OCT with standard methods, ideally such as nuclear magnetic resonance spectroscopy, is necessary.
Capacitance imaging of the skin surface
Authors: Batisse Dominique , Giron Franck , Lévêque Jean Luc 
Published: April 2006

Background/aims: A new device allowing recording capacitance images of the skin surface was recently presented. Parameters, extracted from the gray‐level histogram of the images, are tested for a new approach of skin surface hydration measurement in comparison with the classical capacitance method. Illustration of the interest of having both images and parameters for studying the homogeneity and the level of skin surface hydration are presented.Methods: Software for selecting a region of interest from an image and measuring the parameters derived from its gray‐level histogram was used to characterize skin hydration.Results: There is a very close correlation between a Corneometer and the parameters extracted from the SkinChip measurements. The importance of having capacitance images of skin is demonstrated in case of non‐homogeneity of the skin hydration, either because of photoaging or following an inflammation process.Conclusion: Capacitance imaging is a necessary tool for both completely describing and quantifying skin surface hydration.
Atmospheric nitrogen deposition has caused nitrogen enrichment and eutrophication of lakes in the northern hemisphere
Authors: BERGSTRÖM ANN‐KRISTIN , JANSSON MATS 
Published: April 2006

AbstractWe compiled chemical data and phytoplankton biomass (PB) data (chlorophyll a) from unproductive lakes in 42 different regions in Europe and North America, and compared these data to inorganic nitrogen (N) deposition over these regions. We demonstrate that increased deposition of inorganic N over large areas of Europe and North America has caused elevated concentrations of inorganic N in lakes. In addition, the unproductive lakes in high N deposition areas had clearly higher PB relative to the total phosphorus (P) concentrations illustrating that the elevated inorganic N concentrations has resulted in eutrophication and increased biomass of phytoplankton. The eutrophication caused by inorganic N deposition indicates that PB yield in a majority of lakes in the northern hemisphere is (was) limited by N in their natural state. We, therefore, suggest that P limitation largely concerns lakes where the balance between N and P has been changed because of increased anthropogenic input of N.
Soil carbon balance in a clonal Eucalyptus plantation in Congo: effects of logging on carbon inputs and soil CO2 efflux
Authors: EPRON DANIEL , NOUVELLON YANN , DELEPORTE PHILIPPE , IFO SUSPENS , KAZOTTI GUY , THONGO M'BOU ARMEL , MOUVONDY WELCOME , ANDRE LAURENT SAINT , ROUPSARD OLIVIER , JOURDAN CHRISTOPHE , HAMEL OLIVIER 
Published: April 2006

AbstractSoil CO2 efflux was measured in clear‐cut and intact plots in order to quantify the impact of harvest on soil respiration in an intensively managed Eucalyptus plantation, and to evaluate the increase in heterotrophic component of soil respiration because of the decomposition of harvest residues. Soil CO2 effluxes showed a pronounced seasonal trend, which was well related to the pattern of precipitation and soil water content and were always significantly lower in the clear‐cut plots than in the intact plots. On an annual basis, soil respiration represented 1.57 and 0.91 kgC m−2 yr−1 in intact and clear‐cut plots, respectively. During the first year following harvest, residues have lost 0.79 kgC m−2 yr−1. Our estimate of heterotrophic respiration was calculated assuming that it was similar to soil respiration in the clear‐cut area except that the decomposition of residues did not occur, and it was further corrected for differences in soil water content between intact and clear‐cut plots and for the cessation of leaf and fine root turnover in clear cut. Heterotrophic respiration in clear‐cut plots was estimated at 1.18 kgC m−2 yr−1 whereas it was only 0.65 kgC m−2 yr−1 in intact plots (41% of soil respiration). Assumptions and uncertainties with these calculations are discussed.
Effect of mineral trioxide aggregate on proliferation of cultured human dental pulp cells
Authors: Takita T. , Hayashi M. , Takeichi O. , Ogiso B. , Suzuki N. , Otsuka K. , Ito K. 
Published: April 2006

AbstractAim  To investigate the effect of mineral trioxide aggregate (MTA) on the proliferation of human dental pulp (HDP) cells ex‐vivo.Methodology  Human dental pulp cells were cultured with MTA or calcium hydroxide‐containing cement (Dycal) using culture plate inserts. Control cells were cultured with culture plate inserts only. Cell proliferation was measured for up to 14 days using a Cell Counting kit, and the concentration of calcium ions released from the tested materials was assessed using a Calcium E‐test kit. To confirm that the effect of MTA was attributable to released calcium ions, cell proliferation was measured in the presence of exogenous calcium chloride as a source of calcium ions while in the absence of MTA.Results  Mineral trioxide aggregate significantly stimulated cell proliferation after 12 days, whereas Dycal had no such effect. The number of calcium ions released from MTA was significantly higher than that released from Dycal. Following the addition of calcium chloride, cell proliferation increased in a dose‐dependent manner after 12 days. Moreover, cell proliferation showed a similar pattern whether a given concentration of calcium ions was produced by calcium chloride or by release from MTA.Conclusions  In this ex‐vivo study, the elution components such as calcium ions from MTA had higher proliferation ability of HDP cells than control and Dycal.
Hurler's syndrome: dental findings in a case treated with bone marrow transplantation in infancy
Authors: HINGSTON E. J. , HUNTER M. L. , HUNTER B. , DRAGE N. 
Published: April 2006

Summary. Hurler's syndrome, also known as mucopolysaccharidosis I (MPS I‐H), is a rare condition inherited as an autosomal recessive trait. It is caused by a deficiency in alpha‐l‐iduronidase, an enzyme that participates in the degradation of the glycosaminoglycans (GAGs) heparin sulphate and dermatan sulphate. Children with Hurler's syndrome appear nearly normal at birth but, left untreated, show a progressive mental and physical deterioration caused by a build‐up of GAGs in all organs of the body. Death is often caused by cardiac or respiratory failure and usually occurs before the second decade of life. In recent years, bone marrow transplantation (BMT) has been employed in the management of patients with Hurler's syndrome. However, the dental findings observed in these cases have not previously been reported in the dental literature. Here we report a patient aged 11 years and 6 months, presented to a Specialist Paediatric Dentistry Unit, who was successfully treated by BMT at 18 months of age.
Total antioxidant levels of saliva in children related to caries, age, and gender
Authors: TULUNOGLU Ö. , DEMIRTAS S. , TULUNOGLU I. 
Published: April 2006

Summary.   Aim.  The purpose of this study was to evaluate the relationship between the physicochemical properties of saliva such as flow rate, buffering capacity, pH, calcium level, total protein, total antioxidant status, and dental caries, age, and gender.Material and methods.  The antioxidant activity of saliva was investigated in 80 healthy children aged 7–15 years. They were divided into subgroups according to gender, age (7–10 years and 11–15 years), and caries activity (caries active = CA and caries free = CF). Unstimulated saliva samples were collected from all groups. Flow rates were determined, and samples analysed for pH, buffer capacity, calcium, total proteins, and total antioxidant status. Salivary total antioxidant activity (TAA) was estimated by an adaptation of the ABTS (2,2‐azino‐di (3‐ethylbenzthiazoline‐6‐sulphonate)) assay.Results.  The results indicated that in general, although there was no linear association between salivary flow rate pH and buffering capacity values obtained from different groups, salivary calcium concentration values were found to be higher in caries free groups. Total protein and total antioxidant values were higher in caries active groups except those in the 11‐ to 15‐year‐old girls group.Conclusion.  In general, total protein and total antioxidant insaliva were increased with caries activity. Calcium concentrations in saliva were higher in caries‐free children. In addition, calcium concentration increased with age. Thus, it can be concluded that a linear association exists between calcium concentration age and caries activity. More clinical and laboratory studies are needed to determine the exact relationship between the physicochemical properties of saliva such as flow rate, buffering capacity, pH, calcium level, total protein, total antioxidant status, and dental caries, age, and gender.
Knowledge levels of Korean intensive care nurses towards brain death and organ transplantation
Authors: Kim Jung Ran , Fisher Murray , Elliott Doug 
Published: April 2006

Aims and objectives.  To develop and examine the reliability and validity of an instrument assessing knowledge levels of Korean intensive care unit nurses. To conduct a survey with Korean ICU nurses.Background.  Organ donation from brain dead patients is a contentious issue in Korea following recent legal recognition of brain death, given the context of a Confucian belief system. Implementation of the new Organ Transplant Act has highlighted the importance of identifying Korean intensive care unit nurses’ knowledge regarding brain death and organ donation.Design.  Multi‐stage multi‐method development of an original instrument with a cross‐sectional analysis survey of participants.Method.  An 18‐item instrument was developed based on previous literature and key informant interviews, and validated by an expert panel and a pilot study. A survey was conducted with Korean intensive care unit nurses (n = 520). Principal component analysis with varimax rotation was used to determine construct validity. Item‐to‐total correlations and Cronbach's coefficient alpha were used to determine the scale's internal consistency.Results.  Principal component analysis yielded a two‐component structure: Diagnostic testing and Co‐morbid factors of brain death. The scale demonstrated acceptable internal consistency for the two components (α = 0·74, 0·64, respectively). Most of the participants had a sound knowledge of diagnostic testing for brain death, but demonstrated a lack of knowledge regarding co‐morbid factors of brain dead patients.Conclusions.  The knowledge scale was reliable and valid for this cohort. Further research is warranted in related areas of nursing practice.Relevance to clinical practice.  Effective education for intensive care unit nurses is necessary to increase the organ donor pool in Korea.