bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Bypass of Sucrose Synthase Leads to Low Internal Oxygen and Impaired Metabolic Performance in Growing Potato Tubers
Authors: Bologa Karin L. , Fernie Alisdair R. , Leisse Andrea , Ehlers Loureiro Marcello , Geigenberger Peter 
Published: August 2003

Abstract
Plants possess two alternative biochemical pathways for sucrose (Suc) degradation. One involves hydrolysis by invertase followed by phosphorylation via hexokinase and fructokinase, and the other route—which is unique to plants—involves a UDP-dependent cleavage of Suc that is catalyzed by Suc synthase (SuSy). In the present work, we tested directly whether a bypass of the endogenous SuSy route by ectopic overexpression of invertase or Suc phosphorylase affects internal oxygen levels in growing tubers and whether this is responsible for their decreased starch content. (a) Oxygen tensions were lower within transgenic tubers than in wild-type tubers. Oxygen tensions decreased within the first 10 mm of tuber tissue, and this gradient was steeper in transgenic tubers. (b) Invertase-overexpressing tubers had higher activities of glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, and alcohol dehydrogenase, and (c) higher levels of lactate. (d) Expression of a low-oxygen-sensitive Adh1-β-glucuronidase reporter gene construct was more strongly induced in the invertase-overexpressing background compared with wild-type background. (e) Intact transgenic tubers had lower ATP to ADP ratios than the wild type. ATP to ADP ratio was restored to wild type, when discs of transgenic tubers were incubated at 21% (v/v) oxygen. (f) Starch decreased from the periphery to the center of the tuber. This decrease was much steeper in the transgenic lines, leading to lower starch content especially near the center of the tuber. (g) Metabolic fluxes (based on redistribution of 14C-glucose) and ATP to ADP ratios were analyzed in more detail, comparing discs incubated at various external oxygen tensions (0%, 1%, 4%, 8%, 12%, and 21% [v/v]) with intact tubers. Discs of Suc phosphorylase-expressing lines had similar ATP to ADP ratios and made starch as fast as wild type in high oxygen but had lower ATP to ADP ratios and lower rates of starch synthesis than wild type at low-oxygen tensions typical to those found inside an intact tuber. (h) In discs of wild-type tubers, subambient oxygen concentrations led to a selective increase in the mRNA levels of specific SuSy genes, whereas the mRNA levels of genes encoding vacuolar and apoplastic invertases decreased. (i) These results imply that repression of invertase and mobilization of Suc via the energetically less costly route provided by SuSy is important in growing tubers because it conserves oxygen and allows higher internal oxygen tensions to be maintained than would otherwise be possible.
Gene Expression Profiling in Response to Ultraviolet Radiation in Maize Genotypes with Varying Flavonoid Content
Authors: Casati Paula , Walbot Virginia 
Published: August 2003

Abstract
Microarray hybridization was used to assess acclimation responses to four UV regimes by near isogenic maize (Zea mays) lines varying in flavonoid content. We found that 355 of the 2,500 cDNAs tested were regulated by UV radiation in at least one genotype. Among these, 232 transcripts are assigned putative functions, whereas 123 encode unknown proteins. UV-B increased expression of stress response and ribosomal protein genes, whereas photosynthesis-associated genes were down-regulated; lines lacking UV-absorbing pigments had more dramatic responses than did lines with these pigments, confirming the shielding role of these compounds. Sunlight filtered to remove UV-B or UV-B plus UV-A resulted in significant expression changes in many genes not previously associated with UV responses. Some pathways regulated by UV radiation are shared with defense, salt, and oxidative stresses; however, UV-B radiation can activate additional pathways not shared with other stresses.
Changes in the Redox Potential of Primary and Secondary Electron-Accepting Quinones in Photosystem II Confer Increased Resistance to Photoinhibition in Low-Temperature-Acclimated Arabidopsis
Authors: Sane Prafullachandra Vishnu , Ivanov Alexander G. , Hurry Vaughan , Huner Norman P.A. , Öquist Gunnar 
Published: August 2003

AbstractExposure of control (non-hardened) Arabidopsis leaves for 2 h at high irradiance at 5°C resulted in a 55% decrease in photosystem II (PSII) photochemical efficiency as indicated by F v /F m. In contrast, cold-acclimated leaves exposed to the same conditions showed only a 22% decrease in F v /F m. Thermoluminescence was used to assess the possible role(s) of PSII recombination events in this differential resistance to photoinhibition. Thermoluminescence measurements of PSII revealed that S2QA - recombination was shifted to higher temperatures, whereas the characteristic temperature of the S2QB - recombination was shifted to lower temperatures in cold-acclimated plants. These shifts in recombination temperatures indicate higher activation energy for the S2QA - redox pair and lower activation energy for the S2QB - redox pair. This results in an increase in the free-energy gap between P680+QA - and P680+Pheo- and a narrowing of the free energy gap between primary and secondary electron-accepting quinones in PSII electron acceptors. We propose that these effects result in an increased population of reduced primary electron-accepting quinone in PSII, facilitating non-radiative P680+QA - radical pair recombination. Enhanced reaction center quenching was confirmed using in vivo chlorophyll fluorescence-quenching analysis. The enhanced dissipation of excess light energy within the reaction center of PSII, in part, accounts for the observed increase in resistance to high-light stress in cold-acclimated Arabidopsis plants.
PAUSEDEncodes the Arabidopsis Exportin-t Ortholog
Authors: Hunter Christine A. , Aukerman Milo J. , Sun Hui , Fokina Maria , Poethig R. Scott 
Published: August 2003

AbstractLos1p/exportin-t (XPOT) mediates the nuclear export of tRNAs in yeast and mammals. The requirements for this transport pathway are unclear, however, because los1 mutations do not affect yeast growth, and the phenotype of XPOT mutations in mammals is unknown. Here, we show that PAUSED (PSD) is the Arabidopsis ortholog of LOS1/XPOT and is capable of rescuing the tRNA export defect of los1 in Brewer's yeast (Saccharomyces cerevisiae), suggesting that its function has been conserved. Putative null alleles of PSD disrupt the initiation of the shoot apical meristem and delay leaf initiation after germination, the emergence of the radicle and lateral roots, and the transition to flowering. Plants doubly mutant for psd and hasty, the Arabidopsis ortholog of exportin 5, are viable but have a more severe phenotype than either single mutant. These results suggest that PSD plays a role in tRNA export in Arabidopsis, but that at least one—and perhaps several—additional tRNA export pathways also exist. The PSD transcript is broadly expressed during development and is alternatively spliced in the 3′-untranslated region. No temporal or spatial difference in the abundance of different splice forms was observed. We propose that the mutant phenotype of psd reflects defects in developmental events and cell/tissue types that require elevated levels of protein synthesis and are therefore acutely sensitive to a reduction in tRNA export.
The Chlamydomonas reinhardtii cia3 Mutant Lacking a Thylakoid Lumen-Localized Carbonic Anhydrase Is Limited by CO2 Supply to Rubisco and Not Photosystem II Function in Vivo
Authors: Hanson David Thomas , Franklin Linda A. , Samuelsson Goran , Badger Murray R. 
Published: August 2003

Abstract
The Chlamydomonas reinhardtii cia3 mutant has a phenotype indicating that it requires high-CO2 levels for effective photosynthesis and growth. It was initially proposed that this mutant was defective in a carbonic anhydrase (CA) that was a key component of the photosynthetic CO2-concentrating mechanism (CCM). However, more recent identification of the genetic lesion as a defect in a lumenal CA associated with photosystem II (PSII) has raised questions about the role of this CA in either the CCM or PSII function. To resolve the role of this lumenal CA, we re-examined the physiology of the cia3 mutant. We confirmed and extended previous gas exchange analyses by using membrane-inlet mass spectrometry to monitor16O2,18O2, and CO2 fluxes in vivo. The results demonstrate that PSII electron transport is not limited in the cia3 mutant at low inorganic carbon (Ci). We also measured metabolite pools sizes and showed that the RuBP pool does not fall to abnormally low levels at low Ci as might be expected by a photosynthetic electron transport or ATP generation limitation. Overall, the results demonstrate that under low Ci conditions, the mutant lacks the ability to supply Rubisco with adequate CO2 for effective CO2 fixation and is not limited directly by any aspect of PSII function. We conclude that the thylakoid CA is primarily required for the proper functioning of the CCM at low Ci by providing an ample supply of CO2 for Rubisco.
TaVRT-1, a Putative Transcription Factor Associated with Vegetative to Reproductive Transition in Cereals
Authors: Danyluk Jean , Kane Ndjido A. , Breton Ghislain , Limin Allen E. , Fowler D. Brian , Sarhan Fathey 
Published: August 2003

Abstract
The molecular genetics of vernalization, defined as the promotion of flowering by cold treatment, is still poorly understood in cereals. To better understand this mechanism, we cloned and characterized a gene that we named TaVRT-1 (wheat [Triticum aestivum] vegetative to reproductive transition-1). Molecular and sequence analyses indicated that this gene encodes a protein homologous to the MADS-box family of transcription factors that comprises certain flowering control proteins in Arabidopsis. Mapping studies have localized this gene to the Vrn-1 regions on the long arms of homeologous group 5 chromosomes, regions that are associated with vernalization and freezing tolerance (FT) in wheat. The level of expression of TaVRT-1 is positively associated with the vernalization response and transition from vegetative to reproductive phase and is negatively associated with the accumulation of COR genes and degree of FT. Comparisons among different wheat genotypes, near-isogenic lines, and cereal species, which differ in their vernalization response and FT, indicated that the gene is inducible only in those species that require vernalization, whereas it is constitutively expressed in spring habit genotypes. In addition, experiments using both the photoperiod-sensitive barley (Hordeum vulgare cv Dicktoo) and short or long day de-acclimated wheat revealed that the expression of TaVRT-1 is also regulated by photoperiod. These expression studies indicate that photoperiod and vernalization may regulate this gene through separate pathways. We suggest that TaVRT-1 is a key developmental gene in the regulatory pathway that controls the transition from the vegetative to reproductive phase in cereals.
Thermotolerant Guard Cell Protoplasts of Tree Tobacco Do Not Require Exogenous Hormones to Survive in Culture and Are Blocked from Reentering the Cell Cycle at the G1-to-S Transition
Authors: Gushwa Nathan N. , Hayashi Derek , Kemper Andrea , Abram Beverly , Taylor Jane E. , Upton Jason , Tay Chloe F. , Fiedler Sarah , Pullen Sam , Miller Linnsey P. , Tallman Gary 
Published: August 2003

Abstract
When guard cell protoplasts (GCPs) of tree tobacco [Nicotiana glauca (Graham)] are cultured at 32°C with an auxin (1-napthaleneacetic acid) and a cytokinin (6-benzylaminopurine), they reenter the cell cycle, dedifferentiate, and divide. GCPs cultured similarly but at 38°C and with 0.1 μm ± -cis,trans-abscisic acid (ABA) remain differentiated. GCPs cultured at 38°C without ABA dedifferentiate partially but do not divide. Cell survival after 1 week is 70% to 80% under all of these conditions. In this study, we show that GCPs cultured for 12 to 24 h at 38°C accumulate heat shock protein 70 and develop a thermotolerance that, upon transfer of cells to 32°C, enhances cell survival but inhibits cell cycle reentry, dedifferentiation, and division. GCPs dedifferentiating at 32°C require both 1-napthaleneacetic acid and 6-benzylaminopurine to survive, but thermotolerant GCPs cultured at 38°C ± ABA do not require either hormone for survival. Pulse-labeling experiments using 5-bromo-2-deoxyuridine indicate that culture at 38°C ± ABA prevents dedifferentiation of GCPs by blocking cell cycle reentry at G1/S. Cell cycle reentry at 32°C is accompanied by loss of a 41-kD polypeptide that cross-reacts with antibodies to rat (Rattus norvegicus) extracellular signal-regulated kinase 1; thermotolerant GCPs retain this polypeptide. A number of polypeptides unique to thermotolerant cells have been uncovered by Boolean analysis of two-dimensional gels and are targets for further analysis. GCPs of tree tobacco can be isolated in sufficient numbers and with the purity required to study plant cell thermotolerance and its relationship to plant cell survival, growth, dedifferentiation, and division in vitro.
Ferenczi and Jung: some parallel lines?1
Authors: Haynal André , Falzeder Ernst 
Published: August 2003

Abstract:In the complexity of the entangled interactions within the group of psychoanalytical pionneers, their divergent interests and views, the Ferenczi‐Jung relationship is of particular interest given the importance that both had in the field of the history of ideas. It is striking to discover some parallel lines, but interpersonal, institutional and socio‐cultural factors contributed to the fact that this peaceful and complementary collaboration was not possible in the long run. Perhaps for the present generation, in retrospective, it is easier to notice seminal strokes and also some deficiencies in all these thinkers.
A dialogue of unconsciouses A contribution to the panel ‘Jung and Ferenczi – The Emergent Conversation’
Authors: Vida Judith E. 
Published: August 2003

Abstract:I want to explore the notion of ‘mutual introjection, the developmental essence of an autobiographical dialogue’, an idea that has recently crystallized in the continuing collaborative work of Gershon J. Molad of Israel and myself concerning the autobiographical contribution to the dialogue between analysts (Molad & Vida 2002). One of the sources of this crystallization is the experience of my consultative relationship with a Jungian colleague, who, after reading some of this collaborative work, paraphrased Jung's implication that if, in the course of treatment, the doctor is not as transformed as the patient, nothing has happened (1946). In this paper, I want to breathe some life into these theoretical‐sounding words: ‘mutual introjection, the developmental essence of an autobiographical dialogue’.
Le Pen's comeback: the 2002 French presidential election
Authors: Mayer Nonna 
Published: August 2003

How could the French far right draw nearly 20% of the valid votes in the first round of the 2002 presidential election? Who are these voters and have they changed? Can this happen again? To answer these questions we rely on a three wave panel survey of 10,000 interviews conducted before the first round of the presidential election, after the second round and after the second round of the parliamentary elections. It shows that the main features of the Le Pen vote – xenophobic, authoritarian, mostly male – have not changed. But there has been an important shift in its social bases, from urban to rural areas and from young to elderly voters.Comment l'extrême droite française a‐t‐elle pu attirer près de 20% des suffrages exprimés au premier tour des élections présidentielles de 2002? Qui est son électorat et a‐t‐il évolué? Est‐ce que cela peut se reproduire? Pour répondre à ces questions, l'article s'appuie sur une étude par panel en trois temps comptant 10,000 entretiens menés avant le premier tour de l'élection présidentielle, après le second tour, puis après le deuxième tour des élections parlementaires. Elle montre que les principales caractéristiques de l'électorat de Le Pen – xénophobe, partisan de l'autorité, en majorité masculin – n'a pas changé. Toutefois, il s'est produit un décalage important de ses bases sociales, des zones urbaines aux zones rurales, et des jeunes vers les personnes âgées.
From Transnationalism to the Emergence of a New Transnational Research Field
Authors: Sørensen Ninna Nyberg 
Published: August 2003

Sallie Westwood and Annie Phizacklea Trans‐nationalism and the politics of belongingMichael Peter Smith Transnational urbanism: locating globalizationLudger Pries (ed.) New transnational social spaces: international migration and transnational companies in the early twenty‐first century
Institutional and District‐Level Sources of Competition in State Legislative Elections*
Authors: Hogan Robert E. 
Published: August 2003

Objectives. What are the sources of partisan competition in state legislative elections? Specifically, what impact do institutional features have relative to district‐level conditions on competition between party nominees?Methods. Using data from 30 states in 1994 and 1996, a range of factors are examined to determine their influence on both the likelihood that a race is contested and the degree of competition that results.Results. Multiple regression analyses indicate that a district's characteristics, measured as social and partisan diversity, have a strong and durable influence on elections. Contested elections are more likely and competition levels are higher in districts with heterogeneous populations. Institutional characteristics such as legislative professionalism also have a large influence, although the direction of their impact varies by stage of the electoral process examined. For example, professionalism increases the likelihood that an election is contested, but leads to a lower level of competition between opposing candidates.Conclusions. District‐level conditions have a large influence on competition; however, incentives created by institutional features are also critical for understanding the competitiveness of state legislative elections.
Presidential Success in the Realm of Foreign Affairs: Institutional Reform and the Role of House Committees*
Authors: Marshall Bryan W. 
Published: August 2003

Objective This analysis focuses on institutional reform and the House foreign policy committees to assess the resurgent‐Congress explanation of presidential success in international affairs between 1953–1998.Method Logit models are used to determine the changing effects on presidential success resulting from the support of chairmen and the president's co‐partisans on the foreign policy committees due to the 1970s congressional reforms.Results The analysis illustrates differences in the effects of committee leaders and committee co‐partisans on roll‐call success before and after the reforms. Also, contrasts are found in the effects of the foreign policy panels that differentially influence presidential success.Conclusion The article offers evidence that the institutional reforms that changed the House policy process from one dominated by committee chairs to one responsive to political parties significantly altered presidential success. These findings emphasize the importance of the changing congressional environment in explaining presidential success in foreign policy.
Genome-Wide Expression Analyses of Gene Regulation during Early Development of
Dictyostelium discoideum
Authors: Iranfar Negin , Fuller Danny , Loomis William F. 
Published: August 2003

ABSTRACT

Using genome-wide microarrays, we recognized 172 genes that are highly expressed at one stage or another during multicellular development of
Dictyostelium discoideum
. When developed in shaken suspension, 125 of these genes were expressed if the cells were treated with cyclic AMP (cAMP) pulses at 6-min intervals between 2 and 6 h of development followed by high levels of exogenous cAMP. In the absence of cAMP treatment, only three genes,
carA
,
gbaB
, and
pdsA
, were consistently expressed. Surprisingly, 14 other genes were induced by cAMP treatment of mutant cells lacking the activatable adenylyl cyclase, ACA. However, these genes were not cAMP induced if both of the developmental adenylyl cyclases, ACA and ACR, were disrupted, showing that they depend on an internal source of cAMP. Constitutive activity of the cAMP-dependent protein kinase PKA was found to bypass the requirement of these genes for adenylyl cyclase and cAMP pulses, demonstrating the critical role of PKA in transducing the cAMP signal to early gene expression. In the absence of constitutive PKA activity, expression of later genes was strictly dependent on ACA in pulsed cells.
Diverse Sequences within Tlr Elements Target Programmed DNA Elimination in
Tetrahymena thermophila
Authors: Wuitschick Jeffrey D. , Karrer Kathleen M. 
Published: August 2003

ABSTRACT

Tlr elements are a novel family of ∼30 putative mobile genetic elements that are confined to the germ line micronuclear genome in
Tetrahymena thermophila
. Thousands of diverse germ line-limited sequences, including the Tlr elements, are specifically eliminated from the differentiating somatic macronucleus. Macronucleus-retained sequences flanking deleted regions are known to contain
cis
-acting signals that delineate elimination boundaries. It is unclear whether sequences within deleted DNA also play a regulatory role in the elimination process. In the current study, an in vivo DNA rearrangement assay was used to identify internal sequences required in
cis
for the elimination of Tlr elements. Multiple, nonoverlapping regions from the ∼23-kb Tlr elements were independently sufficient to stimulate developmentally regulated DNA elimination when placed within the context of flanking sequences from the most thoroughly characterized family member, Tlr1. Replacement of element DNA with macronuclear or foreign DNA abolished elimination activity. Thus, diverse sequences dispersed throughout Tlr DNA contain
cis
-acting signals that target these elements for programmed elimination. Surprisingly, Tlr DNA was also efficiently deleted when Tlr1 flanking sequences were replaced with DNA from a region of the genome that is not normally associated with rearrangement, suggesting that specific flanking sequences are not required for the elimination of Tlr element DNA.
Glucose Uptake in
Trichoderma harzianum
: Role of
gtt1
Authors: Delgado-Jarana Jesús , Moreno-Mateos Miguel Ángel , Benítez Tahía 
Published: August 2003

ABSTRACT

Using a differential display technique, the gene
gtt1
, which codes for a high-affinity glucose transporter, has been cloned from the mycoparasite fungus
Trichoderma harzianum
CECT 2413. The deduced protein sequence of the
gtt1
gene shows the 12 transmembrane domains typical of sugar transporters, together with certain residues involved in glucose uptake, such as a conserved arginine between domains IV and V and an aromatic residue (Phe) in the sequence of domain X. The
gtt1
gene is transcriptionally regulated, being repressed at high levels of glucose. When carbon sources other than glucose are utilized,
gtt1
repression is partially alleviated. Full derepression of
gtt1
is obtained when the fungus is grown in the presence of low carbon source concentrations. This regulation pattern correlates with the role of this gene in glucose uptake during carbon starvation. Gene expression is also controlled by pH, so that the
gtt1
gene is repressed at pH 6 but not at pH 3, a fact which represents a novel aspect of the influence of pH on the gene expression of transporters. pH also affects glucose transport, since a strongly acidic pH provokes a 40% decrease in glucose transport velocity. Biochemical characterization of the transport shows a very low

K
m

value for glucose (12 μM). A transformant strain that overexpresses the
gtt1
gene shows a threefold increase in glucose but not galactose or xylose uptake, a finding which confirms the role of the
gtt1
gene in glucose transport. The cloning of the first filamentous ascomycete glucose transporter is the first step in elucidating the mechanisms of glucose uptake and carbon repression in aerobic fungi.