bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calcium Sensors and Their Interacting Protein Kinases: Genomics of the Arabidopsis and Rice CBL-CIPK Signaling Networks
Authors: Kolukisaoglu Üner , Weinl Stefan , Blazevic Dragica , Batistic Oliver , Kudla Jörg 
Published: January 2004

Abstract
Calcium signals mediate a multitude of plant responses to external stimuli and regulate a wide range of physiological processes. Calcium-binding proteins, like calcineurin B-like (CBL) proteins, represent important relays in plant calcium signaling. These proteins form a complex network with their target kinases being the CBL-interacting protein kinases (CIPKs). Here, we present a comparative genomics analysis of the full complement of CBLs and CIPKs in Arabidopsis and rice (Oryza sativa). We confirm the expression and transcript composition of the 10 CBLs and 25 CIPKs encoded in the Arabidopsis genome. Our identification of 10 CBLs and 30 CIPKs from rice indicates a similar complexity of this signaling network in both species. An analysis of the genomic evolution suggests that the extant number of gene family members largely results from segmental duplications. A phylogenetic comparison of protein sequences and intron positions indicates an early diversification of separate branches within both gene families. These branches may represent proteins with different functions. Protein interaction analyses and expression studies of closely related family members suggest that even recently duplicated representatives may fulfill different functions. This work provides a basis for a defined further functional dissection of this important plant-specific signaling system.
Correlation of ASN2 Gene Expression with Ammonium Metabolism in Arabidopsis
Authors: Wong Hon-Kit , Chan Hiu-Ki , Coruzzi Gloria M. , Lam Hon-Ming 
Published: January 2004

Abstract
In Arabidopsis, asparagine (Asn) synthetase is encoded by a small gene family (ASN1, ASN2, and ASN3). It has been shown that ASN1 and ASN2 exhibit reciprocal gene expression patterns toward light and metabolites. Moreover, changes in total free Asn levels parallel the expression of ASN1, but not ASN2. In this study, we show that ASN2 expression correlates with ammonium metabolism. We demonstrate that the light induction of ASN2 is ammonium dependent. The addition and removal of ammonium exerted fast and reciprocal effects on the levels of ASN2 mRNA, specifically under light-grown conditions. NaCl and cold stress increased cellular free ammonium and ASN2 mRNA levels in a coordinated manner, suggesting that the effects of stress on ASN2 expression may be mediated via accumulation of ammonium. The correlation between ASN2 and cellular ammonium metabolism was further demonstrated by analysis of ASN2 transgenic plants. When plants were grown on Murashige and Skoog medium containing 50 mm ammonium, ASN2 overexpressors accumulated less endogenous ammonium compared with the wild-type Colombia-0 and ASN2 underexpressors. When plants were subjected to high-light irradiance, ammonium levels built up. Under such conditions, ASN2 underexpressors accumulated more endogenous ammonium than the wild-type Colombia-0 and ASN2 overexpressors. These results support the notion that ASN2 is closely correlated to ammonium metabolism in higher plants.
Is Each Light-Harvesting Complex Protein Important for Plant Fitness?
Authors: Ganeteg Ulrika , Külheim Carsten , Andersson Jenny , Jansson Stefan 
Published: January 2004

Abstract
Many of the photosynthetic genes are conserved among all higher plants, indicating that there is strong selective pressure to maintain the genes of each protein. However, mutants of these genes often lack visible growth phenotypes, suggesting that they are important only under certain conditions or have overlapping functions. To assess the importance of specific genes encoding the light-harvesting complex (LHC) proteins for the survival of the plant in the natural environment, we have combined two different scientific traditions by using an ecological fitness assay on a set of genetically modified Arabidopsis plants with differing LHC protein contents. The fitness of all of the LHC-deficient plants was reduced in some of the growth environments, supporting the hypothesis that each of the genes has been conserved because they provide ecological flexibility, which is of great adaptive value given the highly variable conditions encountered in nature.
A Methyl Viologen-Resistant Mutant of Arabidopsis, Which Is Allelic to Ozone-Sensitive rcd1, Is Tolerant to Supplemental Ultraviolet-B Irradiation
Authors: Fujibe Takahiro , Saji Hikaru , Arakawa Keita , Yabe Naoto , Takeuchi Yuichi , Yamamoto Kotaro T. 
Published: January 2004

Abstract
To better understand the role of active oxygen species (AOS) in acquired resistance to increased levels of ultraviolet (UV)-B irradiation in plants, we isolated an Arabidopsis mutant that is resistant to methyl viologen, and its sensitivity to UV-B was investigated. A complementation test revealed that the obtained mutant was allelic to the ozone-sensitive radical-induced cell death1-1 (rcd1-1). Therefore, this mutant was named rcd1-2. rcd1-2 was recessive and nearly 4-fold more resistant to methyl viologen than wild type. It exhibited a higher tolerance to short-term UV-B supplementation treatments than the wild type: UV-B-induced formation of cyclobutane pyrimidine dimers was reduced by one-half after 24 h of exposure; the decrease in quantum yield of photosystem II was also diminished by 40% after 12 h of treatment. Furthermore, rcd1-2 was tolerant to freezing. Steady-state mRNA levels of plastidic Cu/Zn superoxide dismutase and stromal ascorbate peroxidase were higher in rcd1-2 than in wild type, and the mRNA level of the latter enzyme was enhanced by UV-B exposure more effectively in rcd1-2. UV-B-absorbing compounds were more accumulated in rcd1-2 than in wild type after UV-B exposure for 24 h. These findings suggest that rcd1-2 methyl viologen resistance is due to the enhanced activities of the AOS-scavenging enzymes in chloroplasts and that the acquired tolerance to the short-term UV-B exposure results from a higher accumulation of sunscreen pigments. rcd1 appears to be a mutant that constitutively shows stress responses, leading to accumulation of more pigments and AOS-scavenging enzymes without any stresses.
RHM2 Is Involved in Mucilage Pectin Synthesis and Is Required for the Development of the Seed Coat in Arabidopsis
Authors: Usadel Björn , Kuschinsky Anja M. , Rosso Mario G. , Eckermann Nora , Pauly Markus 
Published: January 2004

Abstract
Pectins are major components of primary plant cell walls and the seed mucilage of Arabidopsis. Despite progress in the structural elucidation of pectins, only very few enzymes participating in or regulating their synthesis have been identified. A first candidate gene involved in the synthesis of pectinaceous rhamnogalacturonan I is RHM2, a putative plant ortholog to NDP-rhamnose biosynthetic enzymes in bacteria. Expression studies with a promoter β-glucuronidase construct and reverse transcription PCR data show that RHM2 is expressed ubiquitously. Rhm2 T-DNA insertion mutant lines were identified using a reverse genetics approach. Analysis of the rhm2 seeds by various staining methods and chemical analysis of the mucilage revealed a strong reduction of rhamnogalacturonan I in the mucilage and a decrease of its molecular weight. In addition, scanning electron microscopy of the seed surface indicated a distorted testa morphology, illustrating not only a structural but also a developmental role for RGI or rhamnose metabolism in proper testa formation.
MUCILAGE-MODIFIED4 Encodes a Putative Pectin Biosynthetic Enzyme Developmentally Regulated by APETALA2, TRANSPARENT TESTA GLABRA1, and GLABRA2 in the Arabidopsis Seed Coat
Authors: Western Tamara L. , Young Diana S. , Dean Gillian H. , Tan Wei Ling , Samuels A. Lacey , Haughn George W. 
Published: January 2004

Abstract
The Arabidopsis seed coat epidermis undergoes a complex process of differentiation that includes the biosynthesis and secretion of large quantities of pectinaceous mucilage, cytoplasmic rearrangement, and secondary cell wall biosynthesis. Mutations in MUM4 (MUCILAGE-MODIFIED4) lead to a decrease in seed coat mucilage and incomplete cytoplasmic rearrangement. We show that MUM4 encodes a putative NDP-l-rhamnose synthase, an enzyme required for the synthesis of the pectin rhamnogalacturonan I, the major component of Arabidopsis mucilage. This result suggests that the synthesis of monosaccharide substrates is a limiting factor in the biosynthesis of pectinaceous seed coat mucilage. In addition, the reduced cytoplasmic rearrangement observed in the absence of a key enzyme in pectin biosynthesis in mum4 mutants establishes a causal link between mucilage production and cellular morphogenesis. The cellular phenotype seen in mum4 mutants is similar to that of several transcription factors (AP2 [APETALA2], TTG1 [TRANSPARENT TESTA GLABRA1], TTG2 MYB61, and GL2 [GLABRA2]). Expression studies suggest that MUM4 is developmentally regulated in the seed coat by AP2, TTG1, and GL2, whereas TTG2 and MYB61 appear to be regulating mucilage production through alternate pathway(s). Our results provide a framework for the regulation of mucilage production and secretory cell differentiation.
Competition and Costs: Evidence from Competitive Tendering in the Scottish National Health Service
Authors: Milne Robin G. , Wright Robert E. 
Published: January 2004

AbstractThis paper estimates the impact of competitive tendering on cleaning costs in Scottish National Health Service hospitals. Unlike previous studies, which have relied on cross‐sectional data, a five‐year balanced panel of 176 hospitals is used to estimate a series of fixed effects regression models. These panel estimates suggest that previous studies have likely over‐estimated the cost‐savings associated with competitive tendering. The findings also suggest that the lower costs associated with competitive tendering have more to do with auction theory than with any intrinsic efficiency of the private sector.
A Permanent Change in the Route to Owner Occupation?
Authors: Andrew Mark 
Published: January 2004

AbstractThis paper attempts to explain why home ownership rates among young adults fell in the early 1990s when various indicators suggested it had become more affordable. As a potential explanation, we focus on the relatively slower growth in their incomes and argue that this could signal a fundamental change in behaviour, a change in route adopted into owner occupation, induced by structural economic change. In examining the implications for housing tenure, we use a conditional fixed effects multinomial logit model to exploit the information on the tenure choice and the timing of transitions in the British Household Panel Survey. Our results reveal that relatively slower income growth contributed significantly to this decline and that ignoring the intertemporal correlation in micro‐panels generates inconsistent results.
Multinationals and Training: Some Evidence from Irish Manufacturing Industries
Authors: Barry Frank , Görg Holger , Strobl Eric 
Published: January 2004

AbstractThis paper sets out to analyse the effect of plant and sectoral level characteristics on the provision of training to employees using plant level data for Irish manufacturing. There is no clear evidence that foreign owned plants are more likely to provide training. By contrast, we find that they spend less than domestic plants on training, ceteris paribus. There is also no evidence that plants that receive training grants are more likely to provide training. This may be likely to reflect the targeting of training grants on plants that are otherwise unlikely to provide much training. We do, however, find that training activity in the sector, either by other foreign or domestic plants, has a positive effect on plant level training activity, at least for domestic owned plants.
The Impact of Computer Use On Earnings in the UK
Authors: Arabsheibani G.R. , Emami J.M. , Marin A. 
Published: January 2004

AbstractThe effect of new technology on relative demands for workers has been the subject of much research in economics. Krueger (1993) and others have studied the impact of computers on earnings in the US and elsewhere. Such studies have been criticised for ignoring the possibility of bias due to unobserved heterogeneity between computer users and non‐users, resulting in computer users not being a random sub‐sample of all workers. As well as looking at the effects of computers on earnings in the UK, this paper extends previous analyses by using a sample selection framework to deal with the bias problem. Results indicate not only that returns to computer use are positive but that it is important to correct for the sample selection bias.
Model Uncertainty, Optimal Monetary Policy and the Preferences of the Fed
Authors: Castelnuovo Efrem , Surico Paolo 
Published: January 2004

AbstractMonetary policy in the US is characterized by a substantial degree of inertia. While in principle this may well be the outcome of an optimizing central bank behaviour, the ability of any derived policy rule to match the data relies on so large weights for interest rate smoothing into policy makers' preferences as to be theoretically flawed. In this paper we investigate whether such a puzzle can be interpreted as resulting from the concern of monetary authorities for potential misspecifications of the macroeconomic dynamics. Accordingly, we propose a novel thick modelling approach that incorporates model uncertainty into the identification of central bank's preferences. The thick robust policy rule shows the kind of smoothness observed in the data without resorting to implausible values for the preference parameters.
A clinical study to assess the ability of a powered toothbrush to remove chlorhexidine/tea dental stain
Authors: Moran J. , Addy M. , Courtney M. , Smith S. , Newcombe R. 
Published: January 2004

AbstractAim: A single‐center, single‐blind, two‐way crossover study was performed to compare the effects of an electric powered toothbrush with a conventional manual toothbrush at removing chlorhexidine/tea tooth staining.Methods: This study used 24 subjects. During the week before the study, the subjects received a prophylaxis to remove all staining, plaque and calculus deposits. On the Monday of the following week, subjects returned to the clinic to receive a further prophylaxis. Under direct supervision, they then rinsed with a 0.2% chlorhexidine mouthrinse, immediately followed by a rinse with a warm black tea solution.This cycle was repeated hourly eight times throughout the day and on the following days until the Friday. Throughout this period, volunteers omitted all other forms of oral hygiene except rinsing with the chlorhexidine mouthwash. On the Friday, the level of stain was assessed both prior to and immediately after brushing with the allocated brush with toothpaste for 1 min. This was done in an adjoining room (out of sight of the clinical scorer). Subjects were then instructed to use the toothbrush at home according to their normal oral hygiene practices. On the following Friday, subjects returned to the clinic when the stain present was re‐assessed. Each subject received a thorough prophylaxis to remove all plaque calculus and staining before starting the second period of the study and again on completion of the study.Results: The study showed relatively little difference between the ability of the two brushes to remove stain at a single test brushing. However, there was some evidence that the powered brush was more effective than the manual brush in minimising stain level during the home use period, overall and in particular for gingival crescent sites.Conclusions: This study has suggested that the powered brush may become more effective at reducing dental stain, the longer the brush is used under normal home conditions.
Effect of oxybenzone on PGE2‐production in vitro and on plaque and gingivitis in vivo
Authors: Jannesson Lillemor , Birkhed Dowen , Scherl Dale , Gaffar Abdul , Renvert Stefan 
Published: January 2004

AbstractObjectives: To study the effect of oxybenzone on prostaglandin E2 (PGE2) production in cell culture and to evaluate the effect of an oxybenzone‐containing dentifrice on plaque and gingivitis in a 6‐week clinical trial.Material and Methods: Human embryo palatal mesenchyme (HEPM) cells were used for testing the inhibition of IL‐1β‐stimulated PGE2‐production in vitro by different concentrations of oxybenzone. For the in vivo study, a total of 66 individuals with a Quigley & Hein plaque index of at least 1.5 and an Ainamo & Bay gingival index of at least 0.2 were included in a double‐blind clinical trial with two cells and a parallel design. Two compositions of fluoride dentifrice were used, one with the addition of 0.5% oxybenzone, and one without. Plaque and gingival index were obtained at three time points: (1) at baseline, (2) after 3 weeks, and (3) after 6 weeks.Results: A dose‐dependent inhibition of PGE2‐production was found in the HEPM cell culture following oxybenzone exposure. In the clinical trial, a 25% reduction of gingival index was observed in the oxybenzone group (p<0.001) after 6 weeks as compared with 2% for the placebo group.Conclusions: These findings indicate that PGE2‐production is reduced by oxybenzone in vitro and that the use of oxybenzone in a dentifrice reduces gingivitis in vivo.
Effects of smoking on clinical parameters and the gingival crevicular fluid levels of IL‐6 and TNF‐α in patients with chronic periodontitis
Authors: Erdemir Ebru Olgun , Duran Ismet , Haliloglu Seyfullah 
Published: January 2004

AbstractObjective: Smoking is an important environmental risk factor for the initiation and progression of periodontal diseases. The aim of this study was to evaluate the effects of smoking on clinical parameters and the gingival crevicular fluid (GCF) contents of the pro‐inflammatory cytokines interleukin‐6 (IL‐6) and tumor necrosis factor‐α (TNF‐α) levels in patients with chronic periodontitis.Material and Methods: The study base consisted of 41 patients including 22 volunteer current smokers with an age range of 32–59 (44.41±7.88) years and 19 volunteer non‐smokers with an age range of 36–59 (46.94±6.07) years. The first month after non‐surgical periodontal therapy was accepted as the baseline of the study. The clinical parameters including plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), clinical attachment loss (CAL) were recorded and GCF samples were collected for analysis of GCF contents of IL‐6 and TNF‐α levels. At the 3rd and 6th months, all of these procedures were repeated.Results: In smokers, only CAL was significantly higher at the 3rd month compared with non‐smokers (p<0.05). GI and BOP were higher in non‐smokers than smokers in both periods (p<0.05). PI showed increases from the initial to the 6th month in smokers (p<0.05). Although the differences between two groups with regard to IL‐6 and TNF‐α were not significant (p>0.05), the total amount of TNF‐α in GCF decreased from the initial to the 6th month in smokers (p<0.05). There were no significant correlations between the mean total amount of IL‐6 and TNF‐α in GCF and clinical parameters in both evaluation periods in smokers (p>0.05).Conclusion: The present study demonstrated that cigarette smoking increases the amount of dental plaque over time in smokers and does not influence GCF contents of IL‐6 and TNF‐α.
Incidence of periodontal attachment loss over 5 years among older South Australians
Authors: Thomson W. Murray , Slade Gary D. , Beck James D. , Elter John R. , Spencer A. John , Chalmers Jane M. 
Published: January 2004

AbstractObjectives: This study described the 5‐year incidence of periodontal attachment loss (ALOSS) among older Australians.Material and method: Clinical examination data were obtained at baseline and 5 years from participants in a cohort study of South Australians aged 60+. Periodontal measurements (gingival recession, GR; probing depth, PD) were made for each tooth at 3 sites. An incident case of ALOSS was identified as an individual having 2+ sites with 3+ mm ALOSS.Results: Some 342 (42.7%) of the 801 individuals examined at baseline were re‐examined after 5 years, contributing longitudinal data from a total of 15,522 sites (6102 in the maxilla and 9420 in the mandible). Most sites showed no change in either GR or PD. Using a threshold of 3+ mm for change, ALOSS occurred at 2.3% of mesiobuccal sites, 2.5% of buccal sites, and 3.4% of distolingual sites. Distolingual sites on molars showed the highest progression rates. The major component of ALOSS was increased GR. Overall, only 10.1% of the observed ALOSS was contributed by increases in PD. Nearly two‐thirds of the sites that experienced ALOSS had <3 mm of ALOSS at baseline. The weighted 5‐year incidence estimate for ALOSS was 43.2% (N=145), and was higher among diabetics or those who had lost 1+ teeth since baseline. Smoking was not a significant predictor.Conclusion: The rates and patterns of ALOSS among older South Australians are largely similar to those recently reported for North Carolinians. Most ALOSS in older people manifests as increases in GR, rather than PD. Diabetics should be targeted for intensive primary and secondary prevention of periodontal disease.