bluuebunny/crossref_metadata_2025_split huggingface dataset:
MAM3 Catalyzes the Formation of All Aliphatic Glucosinolate Chain Lengths in Arabidopsis
Authors: Textor Susanne , de Kraker Jan-Willem , Hause Bettina , Gershenzon Jonathan , Tokuhisa James G. 
Published: March 2007

AbstractChain elongated, methionine (Met)-derived glucosinolates are a major class of secondary metabolites in Arabidopsis (Arabidopsis thaliana). The key enzymatic step in determining the length of the chain is the condensation of acetyl-coenzyme A with a series of ω-methylthio-2-oxoalkanoic acids, catalyzed by methylthioalkylmalate (MAM) synthases. The existence of two MAM synthases has been previously reported in the Arabidopsis ecotype Columbia: MAM1 and MAM3 (formerly known as MAM-L). Here, we describe the biochemical properties of the MAM3 enzyme, which is able to catalyze all six condensation reactions of Met chain elongation that occur in Arabidopsis. Underlining its broad substrate specificity, MAM3 also accepts a range of non-Met-derived 2-oxoacids, e.g. converting pyruvate to citramalate and 2-oxoisovalerate to isopropylmalate, a step in leucine biosynthesis. To investigate its role in vivo, we identified plant lines with mutations in MAM3 that resulted in a complete lack or greatly reduced levels of long-chain glucosinolates. This phenotype could be complemented by reintroduction of a MAM3 expression construct. Analysis of MAM3 mutants demonstrated that MAM3 catalyzes the formation of all glucosinolate chain lengths in vivo as well as in vitro, making this enzyme the major generator of glucosinolate chain length diversity in the plant. The localization of MAM3 in the chloroplast suggests that this organelle is the site of Met chain elongation.
Differential Effects of Sucrose and Auxin on Localized Phosphate Deficiency-Induced Modulation of Different Traits of Root System Architecture in Arabidopsis
Authors: Jain Ajay , Poling Michael D. , Karthikeyan Athikkattuvalasu S. , Blakeslee Joshua J. , Peer Wendy A. , Titapiwatanakun Boosaree , Murphy Angus S. , Raghothama Kashchandra G. 
Published: March 2007

AbstractPhosphorus, one of the essential elements for plants, is often a limiting nutrient in soils. Low phosphate (Pi) availability induces sugar-dependent systemic expression of genes and modulates the root system architecture (RSA). Here, we present the differential effects of sucrose (Suc) and auxin on the Pi deficiency responses of the primary and lateral roots of Arabidopsis (Arabidopsis thaliana). Inhibition of primary root growth and loss of meristematic activity were evident in seedlings grown under Pi deficiency with or without Suc. Although auxin supplementation also inhibited primary root growth, loss of meristematic activity was observed specifically under Pi deficiency with or without Suc. The results suggested that Suc and auxin do not influence the mechanism involved in localized Pi sensing that regulates growth of the primary root and therefore delineates it from sugar-dependent systemic Pi starvation responses. However, the interaction between Pi and Suc was evident on the development of the lateral roots and root hairs in the seedlings grown under varying levels of Pi and Suc. Although the Pi+ Suc− condition suppressed lateral root development, induction of few laterals under the Pi− Suc− condition point to increased sensitivity of the roots to auxin during Pi deprivation. This was supported by expression analyses of DR5∷uidA, root basipetal transport assay of auxin, and RSA of the pgp19 mutant exhibiting reduced auxin transport. A significant increase in the number of lateral roots under the Pi− Suc− condition in the chalcone synthase mutant (tt4-2) indicated a potential role for flavonoids in auxin-mediated Pi deficiency-induced modulation of RSA. The study thus demonstrated differential roles of Suc and auxin in the developmental responses of ontogenetically distinct root traits during Pi deprivation. In addition, lack of cross talk between local and systemic Pi sensing as revealed by the seedlings grown under either the Pi− Suc− condition or in the heterogenous Pi environment highlighted the coexistence of Suc-independent and Suc-dependent regulatory mechanisms that constitute Pi starvation responses.
Increases in the Number of SNARE Genes Parallels the Rise of Multicellularity among the Green Plants
Authors: Sanderfoot Anton 
Published: March 2007

AbstractThe green plant lineage is the second major multicellular expansion among the eukaryotes, arising from unicellular ancestors to produce the incredible diversity of morphologies and habitats observed today. In the unicellular ancestors, secretion of material through the endomembrane system was the major mechanism for interacting and shaping the external environment. In a multicellular organism, the external environment can be made of other cells, some of which may have vastly different developmental fates, or be part of different tissues or organs. In this context, a given cell must find ways to organize its secretory pathway at a level beyond that of the unicellular ancestor. Recently, sequence information from many green plants have become available, allowing an examination of the genomes for the machinery involved in the secretory pathway. In this work, the SNARE proteins of several green plants have been identified. While little increase in gene number was seen in the SNAREs of the early secretory system, many new SNARE genes and gene families have appeared in the multicellular green plants with respect to the unicellular plants, suggesting that this increase in the number of SNARE genes may have some relation to the rise of multicellularity in green plants.
Transcript Profiling of the Anoxic Rice Coleoptile
Authors: Lasanthi-Kudahettige Rasika , Magneschi Leonardo , Loreti Elena , Gonzali Silvia , Licausi Francesco , Novi Giacomo , Beretta Ottavio , Vitulli Federico , Alpi Amedeo , Perata Pierdomenico 
Published: March 2007

AbstractRice (Oryza sativa) seeds can germinate in the complete absence of oxygen. Under anoxia, the rice coleoptile elongates, reaching a length greater than that of the aerobic one. In this article, we compared and investigated the transcriptome of rice coleoptiles grown under aerobic and anaerobic conditions. The results allow drawing a detailed picture of the modulation of the transcripts involved in anaerobic carbohydrate metabolism, suggesting up-regulation of the steps required to produce and metabolize pyruvate and its derivatives. Sugars appear to play a signaling role under anoxia, with several genes indirectly up-regulated by anoxia-driven sugar starvation. Analysis of the effects of anoxia on the expansin gene families revealed that EXPA7 and EXPB12 are likely to be involved in rice coleoptile elongation under anoxia. Genes coding for ethylene response factors and heat shock proteins are among the genes modulated by anoxia in both rice and Arabidopsis (Arabidopsis thaliana). Identification of anoxia-induced ethylene response factors is suggestive because genes belonging to this gene family play a crucial role in rice tolerance to submergence, a process closely related to, but independent from, the ability to germinate under anoxia. Genes coding for some enzymes requiring oxygen for their activity are dramatically down-regulated under anoxia, suggesting the existence of an energy-saving strategy in the regulation of gene expression.
Genetic Interactions of TGA Transcription Factors in the Regulation of Pathogenesis-Related Genes and Disease Resistance in Arabidopsis
Authors: Kesarwani Meenu , Yoo Jungmin , Dong Xinnian 
Published: March 2007

AbstractTGA transcription factors are implicated as regulators of pathogenesis-related (PR) genes because of their physical interaction with the known positive regulator, nonexpresser of PR gene1 (NPR1). A triple-knockout mutant tga2-1 tga5-1 tga6-1 was shown previously to be defective in the induction of PR genes and systemic acquired resistance, confirming their role in disease resistance. However, the contributions of individual TGA factors have been difficult to discern because of functional redundancy among these factors, as well as possible dual functions for some single factors. In this study, we characterized six TGA factors by reverse genetics. We show that TGA3 is required for both basal and 2,6-dichloroisonicotinic acid-induced transcription of PR genes. The tga3-1 mutants were found to be defective in basal pathogen resistance, whereas induced resistance was unaffected. TGA1 and TGA4 play partially redundant roles in regulation of basal resistance, having only moderate effects on PR gene expression. Additionally, an activation-tagged mutant of TGA6 was able to increase basal as well as induced expression of PR1, demonstrating a positive role for TGA6 on PR gene expression. In contrast, TGA2 has repressor activity on PR gene expression even though it can act as a positive regulator in the tga5-1 tga6-1 null mutant background. Finally, we examined the genetic interaction between tga2-2 and suppressor of npr1 inducible1 (sni1-1). TGA2's repressor activity overlaps with SNI1 because the tga2-2 sni1-1 double mutant shows a synergistic effect on PR gene expression.
The RiceYABBY1Gene Is Involved in the Feedback Regulation of Gibberellin Metabolism
Authors: Dai Mingqiu , Zhao Yu , Ma Qian , Hu Yongfeng , Hedden Peter , Zhang Qifa , Zhou Dao-Xiu 
Published: March 2007

AbstractGibberellin (GA) biosynthesis is regulated by feedback control providing a mechanism for GA homeostasis in plants. However, regulatory elements involved in the feedback control are not known. In this report, we show that a rice (Oryza sativa) YABBY1 (YAB1) gene had a similar expression pattern as key rice GA biosynthetic genes GA3ox2 and GA20ox2. Overexpression of YAB1 in transgenic rice resulted in a semidwarf phenotype that could be fully rescued by applied GA. Quantification of the endogenous GA content revealed increases of GA20 and decreases of GA1 levels in the overexpression plants, in which the transcripts of the biosynthetic gene GA3ox2 were decreased. Cosuppression of YAB1 in transgenic plants induced expression of GA3ox2. The repression of GA3ox2 could be obtained upon treatment by dexamethasone of transgenic plants expressing a YAB1-glucocorticoid receptor fusion. Importantly, we show that YAB1 bound to a GA-responsive element within the GA3ox2 promoter. In addition, the expression of YAB1 was deregulated in GA biosynthesis and signaling mutants and could be either transiently induced by GA or repressed by a GA inhibitor. Finally, either overexpression or cosuppression of YAB1 impaired GA-mediated repression of GA3ox2. These data together suggest that YAB1 is involved in the feedback regulation of GA biosynthesis in rice.
Cowpea Chloroplastic ATP Synthase Is the Source of Multiple Plant Defense Elicitors during Insect Herbivory
Authors: Schmelz Eric A. , LeClere Sherry , Carroll Mark J. , Alborn Hans T. , Teal Peter E.A. 
Published: March 2007

Abstract
In cowpea (Vigna unguiculata), fall armyworm (Spodoptera frugiperda) herbivory and oral secretions (OS) elicit phytohormone production and volatile emission due to inceptin [Vu-In; +ICDINGVCVDA−], a peptide derived from chloroplastic ATP synthase γ-subunit (cATPC) proteins. Elicitor-induced plant volatiles can function as attractants for natural enemies of insect herbivores. We hypothesized that inceptins are gut proteolysis products and that larval OS should contain a mixture of related peptides. In this study, we identified three additional cATPC fragments, namely Vu-GE+In [+GEICDINGVCVDA−], Vu-E+In [+EICDINGVCVDA−], and Vu-In−A [+ICDINGVCVD−]. Leaf bioassays for induced ethylene (E) production demonstrated similar effective concentration50 values of 68, 45, and 87 fmol leaf−1 for Vu-In, Vu-E+In, and Vu-GE+In, respectively; however, Vu-In−A proved inactive. Shortly following ingestion of recombinant proteins harboring cATPC sequences, larval OS revealed similar concentrations of the three elicitors with 80% of the potential inceptin-related peptides recovered. Rapidly shifting peptide ratios over time were consistent with continued proteolysis and preferential stability of inceptin. Likewise, larvae ingesting host plants with inceptin precursors containing an internal trypsin cleavage site rapidly lost OS-based elicitor activity. OS containing inceptin elicited a rapid and sequential induction of defense-related phytohormones jasmonic acid, E, and salicylic acid at 30, 120, and 240 min, respectively, and also the volatile (E)-4,8-dimethyl-1,3,7-nonatriene. Similar to established peptide signals such as systemin and flg22, amino acid substitutions of Vu-In demonstrate an essential role for aspartic acid residues and an unaltered C terminus. In cowpea, insect gut proteolysis following herbivory generates inappropriate fragments of an essential metabolic enzyme enabling plant non-self-recognition.
Oxylipins Produced by the 9-Lipoxygenase Pathway inArabidopsisRegulate Lateral Root Development and Defense Responses through a Specific Signaling Cascade
Authors: Vellosillo Tamara , Martínez Marta , López Miguel Angel , Vicente Jorge , Cascón Tomas , Dolan Liam , Hamberg Mats , Castresana Carmen 
Published: March 2007

AbstractArabidopsis thaliana seedling growth with pure oxylipins resulted in root waving, loss of root apical dominance, and decreased root elongation. 9-Hydroxyoctadecatrienoic acid (9-HOT) was a potent inducer of root waving. Studies with noxy2 (for nonresponding to oxylipins2), a new 9-HOT–insensitive mutant, and coronatine insensitive1-1 (jasmonate-insensitive) revealed at least three signaling cascades mediating the oxylipin actions. Treatment with 9-HOT resulted in a reduction in lateral roots and an increase in stage V primordia. Roots showed strong 9-lipoxygenase (9-LOX) activity, and root primordia expressed 9-LOX genes. These results, along with findings that noxy2 and mutants with defective 9-LOX activity showed increased numbers of lateral roots, suggest that 9-HOT, or a closely related 9-LOX product, is an endogenous modulator of lateral root formation. Histochemical and molecular analyses revealed that 9-HOT activated events common to development and defense responses. A subset of 9-HOT–responding root genes was also induced in leaves after 9-HOT treatment or pathogen inoculation. The results that noxy2 displayed altered root development, enhanced susceptibility to Pseudomonas, and reduced the activation of 9-HOT–responding genes are consistent with mechanistic links among these processes. The nature of the changes detected suggests that oxylipins from the 9-LOX pathway function in cell wall modifications required for lateral root development and pathogen arrest.
T-Loop Phosphorylation ofArabidopsisCDKA;1 Is Required for Its Function and Can Be Partially Substituted by an Aspartate Residue
Authors: Dissmeyer Nico , Nowack Moritz K. , Pusch Stefan , Stals Hilde , Inzé Dirk , Grini Paul E. , Schnittger Arp 
Published: March 2007

AbstractAs in other eukaryotes, progression through the cell cycle in plants is governed by cyclin-dependent kinases. Phosphorylation of a canonical Thr residue in the T-loop of the kinases is required for high enzyme activity in animals and yeast. We show that the Arabidopsis thaliana Cdc2+/Cdc28 homolog CDKA;1 is also phosphorylated in the T-loop and that phosphorylation at the conserved Thr-161 residue is essential for its function. A phospho-mimicry T161D substitution restored the primary defect of cdka;1 mutants, and although the T161D substitution displayed a dramatically reduced kinase activity with a compromised ability to bind substrates, homozygous mutant plants were recovered. The rescue by the T161D substitution, however, was not complete, and the resulting plants displayed various developmental abnormalities. For instance, even though flowers were formed, these plants were completely sterile as a result of a failure of the meiotic program, indicating that different requirements for CDKA;1 function are needed during plant development.
Diet, smoking and exercise: interrelationships between adolescent health behaviours
Authors: Coulson N S , Eiser C , Eiser J R 
Published: March 2007

SummaryA questionnaire measuring smoking status, exercise and dietary behaviour was administered to 932 high school pupils during regular classroom periods. Pupils were taken from three year groups which included 327 year 8 (12–13 years), 313 year 9 (13–14 years) and 292 year 10 (14–15 years). Pupils also indicated whether they could recall classroom teaching on 15 food‐ and health‐related issues. Scores were derived representing self‐reported frequency of eating foods that were high in fat, and fresh fruits and vegetables. Smoking was found to be associated with lower levels of exercise, consumption of less fresh foods and greater consumption of fatty foods. In addition, consumption of fresh foods was found to be positively correlated with exercise. These findings have implications for the organization of school‐based health education efforts and suggest that health education programmes need to adopt an integrated approach rather than treat health behaviours in isolation from each other.
Exploration off surface‐textures in congenitally blind infants
Authors: Schellingerhout R , Smitsman A W , van Galen G P 
Published: March 2007

SummaryThe haptic exploratory procedures that eight congenitally blind infants aged 8–24 months used to explore a gradient surface texture were investigated. Exploration of the gradient texture was examined over five sessions with 2 weeks between sessions, followed after 1 week by a sixth session, in which exploration of the gradient texture was compared to exploration of two other textures. Results showed that the infants have a wide range of exploratory strategies available and that the older infants can use these strategies in a specific manner. Results are discussed with reference to current ideas about the exploratory possibilities of congenitally blind infants. Use of texture in the stimulation of exploration of blind infants is discussed.
Selective eaters: a retrospective case note study
Authors: Timimi S , Douglas J , Tsiftsopoulou K 
Published: March 2007

SummaryThe literature on children who present with selective eating is limited to single case studies. This study aims to provide a descriptive clinical profile for these children. Case notes of 33 patients between 4 and 14 years of age, seen in two clinics over a 4‐year‐period were studied. Over two‐thirds of the cases were boys. A significant minority had poor growth or weight gain. The children suffered from anxiety, obsessive compulsive symptoms, both food and non‐food related and often had social and school difficulties. Mealtimes caused immense anxiety for family members and frequent mealtime battles was reported by the parents of the younger selective eaters, whereas parents of older children seemed to have given up trying to change their child's eating habits. A history of depression In at least one parent was found in a third of the parental couples.
ADMA is independently related to flow‐mediated vasodilation in subjects at low cardiovascular risk
Authors: Ardigo D. , Stüehlinger M. , Franzini L. , Valtueña S. , Piatti P. M. , Pachinger O. , Reaven G. M. , Zavaroni I. 
Published: March 2007

AbstractBackground  Increased plasma concentrations of asymmetric dimethylarginine (ADMA) contribute to impair endothelial function in patients with established cardiovascular disease (CVD) and/or individuals with clinical syndromes known to increase CVD. However, the impact of ADMA on endothelial function in apparently healthy individuals has not been determined.Materials and methods  To address this issue, we measured endothelial‐dependent vasodilatation in response to forearm ischaemia (flow‐mediated vasodilatation, FMD) in 111 non‐smoking, healthy volunteers with low CVD risk by the Framingham risk equation. Measurements were also made of multiple anthropometric, metabolic, and dynamic variables related to FMD. l‐arginine and its methylated derivates (ADMA and SDMA) were quantified by high‐liquid pressure chromatography.Results  After adjustment by gender, lower values for FMD were significantly associated with increases in plasma ADMA concentrations (anova linear trend by FMD tertiles, P < 0·05) as well as in brachial artery diameter (partial r = −0·352, P = 0·001), body mass index (−0·337, P = 0·001), fasting insulin (−0·368, P < 0·001) and high‐sensitivity C‐reactive protein (−0·283, P = 0·007) plasma concentrations, and with decreased HDL cholesterol (0·233, P = 0·026). Multiple linear regression analysis indicated that the only statistically significant predictors of FMD were brachial artery diameter (P < 0·001), ADMA (P < 0·05) and fasting plasma insulin (P < 0·001) concentrations.Conclusions  In conclusion, a significant relationship between increases in plasma ADMA concentration and lower values of FMD is not limited to patients with clinical syndromes related to CVD, but can also be seen in healthy subjects at low global CVD risk.
Sources of variation in winter basal metabolic rate in the great tit
Authors: BROGGI J. , HOHTOLA E. , KOIVULA K. , ORELL M. , THOMSON R. L. , NILSSON J.‐Å. 
Published: March 2007

SummaryBasal metabolic rate (BMR) is the most widely used standard measurement of the cost of living. Despite the acknowledged phenotypic flexibility of BMR, little is known about the patterns of variation in wild animal populations.We studied the sources of variation in BMR of great titParus major(L.) among individuals from two wild populations: Oulu (northern Finland) and Lund (southern Sweden) during six consecutive years.By means of a multivariate approach, we found year, locality, date, previous week average minimum temperature, age, body mass, and the interaction between locality and year were the factors retained in the final model, together explaining 71·1% of the total variation in BMR.Birds from Oulu (n = 168) had a higher BMR than Lund birds (n = 156), and their BMR varied more between years than that of Lund birds. The two populations reacted in the same way to the other sources of variation examined.Great tits from both populations showed a positive relationship between BMR and body mass and a negative relationship between BMR and date, previous week average minimum temperature and age.This study highlights the need to standardize BMR measurements when testing predictions about metabolic rates from individuals of wild populations.
The role of MSX1 in tooth agenesis in Iranians
Authors: SEIFI MASSOUD , KAZEMI BAHRAM , GOLKAR PARISA 
Published: March 2007

Introduction.  MSX1 gene has a critical role in craniofacial development, the aim of this case–control study is to test the hypothesis that MSX1 mutation contributes to congenital tooth agenesis in Iranians.Materials and methods.  The study group consisted of 20 affected individuals with tooth agenesis of lower second premolars or upper lateral incisors with mean age of 24.6. The control group consisted of 20 unaffected individuals. DNA was extracted from all 40 individuals; the polymerase chain reaction (PCR) for MSX1 was carried out with Phenol: Chloroform: Isoamylalchol (PCI) extraction method. Ban II restriction digest and agarose gel electrophoresis of the 20 affected individuals verified the presence of mutation in all 20 affected individuals. The unaffected controls did not show any mutation. Statistical analysis performed by the chi‐squared method.Results.  Ban II did not digest PCR product (DNA) in the control group (195 bp band on electrophoresis gel) but digested the affected allele (106 bp and 89 bp bands). There is a statistically significant correlation between tooth agenesis and MSX1 mutation (P < 0.001).Conclusion.  The results indicated that MSX1 gene mutation contributes to tooth agenesis in Iranian individuals. As the timing of tooth calcification can vary, radiographic finding of congenital tooth agenesis can be confirmed by this molecular method during different dental ages to achieve certainty.