bluuebunny/crossref_metadata_2025 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

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

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

Exposure 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

Los1p/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

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

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

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

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

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’.
Hierarchical Tendencies of Capital Markets Among International Financial Centers
Authors: Poon Jessie P.H.
Published: August 2003

Abstract The dramatic evolution of global finance in the last three decades has seen intensified competition among the world's major cities to become prominent control centers of global financial flows. This paper examines the spatial organization and evolution of capital markets in forty‐three world cities from 1980 to 1998. It finds evidence of the strengthening of hierarchical tendencies among world financial and capital cities as they search for ways to differentiate between themselves through financial concentration and productivity. The results also indicate a trend towards the dominance of London and New York in this financial hierarchy, and that top tier cities tend to be characterized by significantly lower levels of market and share concentrations, share trading value, and risks. Finally, important differences in ownership patterns between the capital markets are detected for the top cities of the hierarchy.
Understanding the Non‐Metropolitan—Metropolitan Digital Divide
Authors: Mills Bradford F. , Whitacre Brian E.
Published: August 2003

Abstract A consistent gap exists between home Internet use in metropolitan areas and in non‐metropolitan areas in the U.S. This digital divide may stem from technology differences in home Internet connectivity. Alternatively, differences in education, income, and other household attributes may explain differences in metropolitan and non‐metropolitan area home Internet access. Effective programs to reduce the metropolitan–non‐metropolitan digital divide must be based on an understanding of the relative roles that technology and household characteristics play in determining differential Internet usage. The household Internet adoption decision is modeled using a logit estimation approach with data from the 2001 U.S. Current Population Survey Internet and Computer Use Supplement. A decomposition of separate metropolitan and non‐metropolitan area estimates shows that differences in household attributes, particularly education and income, account for 63 percent of the current metropolitan–non‐metropolitan digital divide. The result raises significant doubts that policies which focus solely on infrastructure and technology access will mitigate the current metropolitan–non‐metropolitan digital divide.
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 belonging

Michael Peter Smith Transnational urbanism: locating globalization

Ludger Pries (ed.) New transnational social spaces: international migration and transnational companies in the early twenty‐first century
The Dynamics of REIT Capital Flows and Returns
Authors: Ling David , Naranjo Andy
Published: August 2003

This study examines the effects of capital flows into the REIT sector on REIT returns and, simultaneously, the effects of REIT returns on subsequent REIT capital flows. The dynamic relation between REIT capital flows and returns is estimated using vector autoregression (VAR) techniques. Unlike static regression techniques, our dynamic model produces estimates of the short‐run relationships, long‐run relationships, impulse response functions and forecast variance decompositions. We find evidence that REIT equity flows are significantly positively related to the prior quarter's flows and negatively related to flows from two quarters ago. The evidence on the responsiveness of flows to prior returns is time‐period specific. In the important post‐1992 subperiod, REIT returns do not significantly affect REIT flows in any of the VAR model specifications. Simultaneously, REIT capital flows do appear to have a significant influence on equity REIT returns.
The Cross Section of Expected REIT Returns
Authors: Chui Andy C. W. , Titman Sheridan , Wei K. C. John
Published: August 2003

In this study, we examine the cross‐sectional determinants of expected REIT returns. We examine both the pre‐ and post‐1990 periods, since the structure of the REIT market changed substantially around 1990. The determinants of expected returns differ between the two subperiods. In the pre‐1990 subperiod, momentum, size, turnover and analyst coverage predict REIT returns. In the post‐1990 period, momentum is the dominant predictor of REIT returns. Given the strength of the momentum effect in the post‐1990 period, we examine it in great detail. For the whole period, and for the post‐1990 period where the momentum profit is strongest, our evidence is generally consistent with the studies on common stocks other than REITs. The only striking exception is that we find that momentum is stronger for the larger REITs rather than for the smaller REITs. In our multiple regressions that include the characteristics as well as interactions between past returns and firm characteristics, the turnover–momentum interaction effect provides the most significant results. More specifically, momentum effects are stronger for more liquid REITs.
International Real Estate Returns: A Multifactor, Multicountry Approach
Authors: Bond Shaun A. , Karolyi G. Andrew , Sanders Anthony B.
Published: August 2003

We examine the risk and return characteristics of publicly traded real estate companies from 14 countries over the period 1990 to 2001. Our data are monthly country‐level commercial real estate indexes constructed by the European Public Real Estate Association (EPRA). We find substantial variation in mean real estate returns and standard deviations across countries. Using various global‐ and country‐level factor models, we find that there is evidence of a strong global market risk component, measured relative to the Morgan Stanley Capital International world index, in most countries. However, even after controlling for the effects of global market risk, an orthogonalized country‐specific market risk factor is highly significant, especially for real estate indexes in Asia–Pacific markets. We find that a country‐specific value risk factor has some explanatory power in addition to the country‐specific market factor, but U.S.‐based market, value and size risk factors do not provide any additional explanatory power. These findings imply that the international diversification opportunities with real estate companies are more complex than previously thought.
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.
The Geography of Need: Spatial Distribution of Barriers to Employment in Metropolitan Detroit
Authors: Allard Scott W. , Tolman Richard M. , Rosen Daniel
Published: August 2003

Although several studies examine the barriers to employment that limit the employability of welfare recipients, they have not analyzed how these barriers might be different for residents of central cities than for residents in surrounding suburban areas. We consider how the prevalence of barriers to employment varies by race and place in metropolitan Detroit. We find that the prevalence of mental health, substance abuse, and domestic violence barriers is higher in suburban areas, and that structural barriers are higher in the central city.
Changes in Family Structure and Child Outcomes: Roles of Economic and Familial Resources
Authors: Ram Bali , Hou Feng
Published: August 2003

This article examines the effects of changes in family structure (from a family with two original parents to a lone‐parent family or a stepfamily) on emotional‐behavioral and cognitive outcomes of young children. We use data from three cycles of the National Longitudinal Surveys of Children and Youth, first conducted in 1994–95, and every 2 years since then. The present analysis is based on data for children, who were 4 to 7 years old at the first cycle. We find that compared with children in families with two original parents, those in lone‐parent and stepparent families are at a disadvantage on every measure of child outcome, even when their initial disadvantages and socioeconomic background are taken into account. We also find that the deterioration in economic resources is more important in explaining the relationship between family structure and cognitive outcomes (such as math and reading scores) but not emotional‐behavioral outcomes, whereas the deterioration in familial resources—ineffective parenting and parental depression, in particular—is more important in explaining the effects on emotional‐behavioral outcomes. The scarcity of material resources mediates the relationship between family structure and cognitive outcomes, whereas the diminution of familial resources mediates the relationship between changes in family structure and emotional‐behavioral outcomes.
Dissipationless Quantum Spin Current at Room Temperature
Authors: Murakami Shuichi , Nagaosa Naoto , Zhang Shou-Cheng
Published: August 2003

Although microscopic laws of physics are invariant under the reversal of the arrow of time, the transport of energy and information in most devices is an irreversible process. It is this irreversibility that leads to intrinsic dissipations in electronic devices and limits the possibility of quantum computation. We theoretically predict that the electric field can induce a substantial amount of dissipationless quantum spin current at room temperature, in hole-doped semiconductors such as Si, Ge, and GaAs. On the basis of a generalization of the quantum Hall effect, the predicted effect leads to efficient spin injection without the need for metallic ferromagnets. Principles found here could enable quantum spintronic devices with integrated information processing and storage units, operating with low power consumption and performing reversible quantum computation.
Genome-Wide Expression Analyses of Gene Regulation during Early Development of
Dictyostelium discoideum
Authors: Iranfar Negin , Fuller Danny , Loomis William F.
Published: August 2003

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

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

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.
Inositol and Phosphate Regulate
GIT1
Transcription and Glycerophosphoinositol Incorporation in
Saccharomyces cerevisiae
Authors: Almaguer C. , Mantella D. , Perez E. , Patton-Vogt J.
Published: August 2003

Glycerophosphoinositol is produced through deacylation of the essential phospholipid phosphatidylinositol. In
Saccharomyces cerevisiae
, the glycerophosphoinositol produced is excreted from the cell but is recycled for phosphatidylinositol synthesis when inositol is limiting. To be recycled, glycerophosphoinositol enters the cell through the permease encoded by
GIT1
. The transport of exogenous glycerophosphoinositol through Git1p is sufficiently robust to support the growth of an inositol auxotroph (
ino1Δ
). We now report that
S. cerevisiae
also uses exogenous phosphatidylinositol as an inositol source. Evidence suggests that phosphatidylinositol is deacylated to glycerophosphoinositol extracellularly before being transported across the plasma membrane by Git1p. A genetic screen identified Pho86p, which is required for targeting of the major phosphate transporter (Pho84p) to the plasma membrane, as affecting the utilization of phosphatidylinositol and glycerophosphoinositol. Deletion of
PHO86
in an
ino1Δ
strain resulted in faster growth when either phosphatidylinositol or glycerophosphoinositol was supplied as the sole inositol source. The incorporation of radiolabeled glycerophosphoinositol into an
ino1Δ pho86Δ
mutant was higher than that into wild-type,
ino1Δ
, and
pho86Δ
strains. All strains accumulated the most
GIT1
transcript when incubated in media limited for inositol and phosphate in combination. However, the
ino1Δ pho86Δ
mutant accumulated approximately threefold more
GIT1
transcript than did the other strains when incubated in inositol-free media containing either high or low concentrations of P
i
. Deletion of
PHO4
abolished
GIT1
transcription in a wild-type strain. These results indicate that the transport of glycerophosphoinositol by Git1p is regulated by factors affecting both inositol and phosphate availabilities and suggest a regulatory connection between phosphate metabolism and phospholipid metabolism.
Canonical Stability of 3-Folds of General Type with pg ≥ 3
Authors: Chen Meng
Published: August 2003

We study the canonical stability of a smooth projective 3-fold V of general type. We prove that |5KV| gives a birational map onto its image provided pg ≥ 4. For those V with pg = 3, |6KV| gives a birational map. Known examples show that both the results are optimal.
On Locally Nonhomogeneous Pseudo–Riemannian Manifolds with Locally Homogeneous Levi–Civita Connections
Authors: Kowalski Oldřich , Vlášek Zdeněk , Opozda Barbara
Published: August 2003

In this paper we make the first steps to a classification of (pseudo-) Riemannian manifolds which are not locally homogeneous but their Levi–Civita connections are homogeneous. The full classification is given for dimension n = 2; in higher dimensions we prove some substantial partial results. In more generality, we are also interested in the difference between the dimension of the algebra of affine Killing vector fields and that of the algebra of metric Killing vector fields (without any homogeneity properties).
Nuclear Parton Distributions in the DGLAP Approach
Authors: Eskola K. J. , Honkanen H. , Kolhinen V. J. , Ruuskanen P. V. , Salgado C. A.
Published: August 2003

Determination of the nuclear parton distributions within the framework of perturbative QCD, the DGLAP equations in particulars, is discussed. Scale and flavour dependent nuclear effects in the parton distributions are compared with the scale and flavour independent parametrizations of HIJING and of the Hard Probe Collaboration. A comparison with the data from deep inelastic lepton-nucleus scattering and the Drell–Yan process in proton-nucleus collisions is shown.
Large pT Hadron Spectra in pp, pA and AA Collisions
Authors: Wang Xin-Nian
Published: August 2003

Large pT particle spectra in p+p, p+A and A+B collisions at different energies are calculated in a QCD parton model. Intrinsic transverse momentum, its broadening due to initial multiple parton scattering are included. These calculations are meant to estimate the normal nuclear effects (parton shadowing, pT broadening or Cronin effect) in high pT hadron spectra in heavy-ion collisions. Comparisons of these calculations with experimental data will help to determine the effect of jet quenching.
Investigation of the Energetics of the Reactions ofNH2Species with Hydrogen and NO on the Pt(100) Surface by the Method of UBI-QEP
Authors: Azizian S. , Iloukhani H.
Published: August 2003

The formation of NH2, adsand its further reactions with hydrogen and NO on the Pt(100) surface were previously studied by the methods of HREELS and TPR, in order to understand the role of amino species in the mechanism of the NO + H2reaction. In this work the method of unity bond index – quadratic exponential potential (UBI-QEP) has been employed to rationalize the experimental findings by calculating the energies associated with the envisaged routes of reactions. It is concluded that the activation energy of formation of NH2, adsis higher than water production. The simplicity of recombinative desorption of N2is due to the decrease of its activation energy because of the destabilizing effect of Oadsand NOads. The rate-determining step of explosive surface reaction in the saturated coadsorption layer of NH2, adsand NOadsis dissociation of NOads. Autocatalytic acceleration of the explosive reactions is due to the decrease of activation energy of the rds by increasing the number adsorption vacant sites. H2O is produced via two different processes with different activation energies. NH3is produced via several paths.
Micropatterning by Wettability Control of the SiO2 Surface with Ultraviolet Irradiation
Authors: Huang Lan , Zhang Yu , Liao Jianhui , Xu Lina , Gu Ning , Shen Haojing
Published: August 2003

A new phenomenon has been described for fabrication micropatterning by changing SiO 2 surface wettability with ultraviolet irradiation. The most possible reason is the elimination of surface oxygen vacancies at bridging sites. With this technique reconstructed, it may be applicable to assembly of microelectronic circuits in the future.
Deposition and Characterization of High Dielectric Thin Films for Memory Device Application
Authors: Kim Hyeong Joon , Shin Ju Cheol , Hwang Cheol Seong , No Sang Yong
Published: August 2003

(Pb,La)TiO 3 (PLT) and Pb(Zr,Ti)O 3 (PZT) thin films were deposited on Pt/SiO2/Si substrate by metal-organic chemical vapor deposition (MOCVD) using a solid delivery system. The domain configurations of the deposited PLT thin films were investigated, and the film with a columnar structure exhibited a very stable write/read operation for the domain memory application. Electrical properties of PLT, PZT and rf-sputter-deposited (Ba,Sr)TiO 3 (BST) thin films were measured, and their conduction mechanisms were analyzed. The composition and thickness uniformity of BST thin films deposited by the low temperature MOCVD method on a patterned wafer with 0.15 μm-diameter contact holes were investigated, and complete thickness and composition uniformity were obtained especially for the case of a dome-wall-type chamber with a wall temperature of 450°C.
Study of Dry Oxidation of Aluminum Nitride on Si(111) Substrate Grown by Metalorganic Chemical Vapor Deposition
Authors: Wang F. , Zhang R. , Xiu X. Q. , Lu D. Q. , Gu S. L. , Shen B. , Shi Y. , Zheng Y. D.
Published: August 2003

We have investigated the dry oxidation behavior of an AlN epilayer on Si(111) substrate by metalorganic chemical vapor deposition (MOCVD) at different temperatures and different oxidation times through XRD analysis and scanning electron microscopy (SEM). The AlN epilayer has been completely oxidized into polycrystalline α- Al 2 O 3 after oxidation at 1100°C for 2 h. The ratio of O 2 to N 2 introduced into the furnace has an influence on the structure of α- Al 2 O 3. There are only α- Al 2 O 3 (104), (113) diffraction peaks in the XRD curve if the O 2: N 2 is lower than 0.2:1. At the temperature over 1100°C, the oxidation is initiated with a rapid oxidation process, followed by a relatively slow process. These two oxidation stages are respectively related to the interfacial reaction mechanism and the diffusion mechanism.
Influence of the Plasma Condition on the Morphology of Vertically Aligned Carbon Nanotube Films Grown by RF Plasma Chemical Vapor Deposition
Authors: Ikuno Takashi , Takahashi Syunji , Kamada Kazunori , Ohkura Shigeharu , Honda Shin-Ich , Katayama Mitsuhiro , Hirao Takashi , Oura Kenjiro
Published: August 2003

Vertically aligned carbon nanotube (VACNT) films have been grown by RF plasma chemical vapor deposition (RF-PECVD) with a controlling plasma condition. From the in situ optical emission spectroscopy (OES) and self-bias measurements, we have investigated the relationship between the morphology of VACNTs and the plasma condition in PECVD. CH radical and atomic hydrogen peaks were prominent in the OES spectra of CH 4 plasma. The plasma condition was changed by varying the interelectrode distance in PECVD. With increasing interelectrode distance, the diameter and density of VACNTs increased as a result of the increase in plasma density, the fraction of CH radicals, and self-bias. It is likely that the fraction of CH radicals in plasma influences promotion of the growth of CNTs, while the self-bias induces their vertical alignment.
Size-Dependence of Nonlinearity in Metal: Dielectric Composite System Induced by Local Field Enhancement
Authors: Ma Guohong , He Jun , Tang Sing-Hai , Sun Wanxin , Shen Zexiang
Published: August 2003

Femtosecond nonlinear optical response of BaTiO 3 and ZrO 2 matrices doped with gold nanoparticle were investigated by off-resonance optical Kerr effect. The experimental results show that the third-order nonlinear optical susceptibility of the composite films strongly depends on metal particle size and matrix refractive index. A calculation based on Lorenz–Mie scattering theory was performed to explain the experimental results. Additionally, optimization of nonlinearity was obtained by considering the particle size and matrices refractive index.
Fourth-Order Variational Mode Solving for Anisotropic Planar Structures
Authors: Uranus H. P. , Hoekstra H. J. W. M. , van Groesen E.
Published: August 2003

A variational method that gives 4th-order accuracy by only using linear basis functions within the computational domain is proposed for the mode solving of anisotropic planar stratified waveguides with diagonal permitivity tensor. A non-uniform mesh is used to get rid of the necessity of incorporating interface corrections and higher-order basis functions, while Richardson-like extrapolation is used to obtain 4th-order accuracy. The scheme was derived for both TE and TM mode analysis and completed with infinite elements as transparent boundary conditions. The use of a simple extrapolation technique to further refine the results by using two consecutive calculated results is also demonstrated.
Extremal Characterization of Band Gaps in Nonlinear Gratings
Authors: van Groesen E. , Sopaheluwakan A.
Published: August 2003

In this paper we present an explicit extremal characterization of the edges of the lowest band gap in gratings; we restrict here to the case of TE-modes, but the TM case can be treated similarly. The characterization is valid for linear and Kerr-nonlinear gratings, for smooth as well as for step-variations of the index and the coefficient of nonlinearity. The variational characterization allows one to derive monotonicity properties by using simple comparison arguments. For instance, the monotonic shift of the band gap as a function of the angle of oblique incidence is proved, leading to a simple criterion for omni-directionally for the band gap. Rough estimates of the band gaps can be obtained by substituting suitable trial fields in the governing functionals, while the same formulation can also be used to design a Finite Element scheme for accurate calculations.
Measuring the Complexity of Currency Markets by Fractal Dimension Analysis
Authors: Soofi Abdol S. , Galka Andreas
Published: August 2003

We use the theory of nonlinear dynamical systems to measure the complexity of currency markets by estimating the correlation dimension of the returns of the Dollar/Pound and Dollar/Yen daily exchange rates (the spot rates). We test the significance of the results by comparing them to correlation dimension estimates for surrogate time series, i.e. stochastic linear time series with the same power spectrum and amplitude distribution as given by the original data. We find discernible nonlinear structure in the returns of the Dollar/Pound daily rate.
Optimal Asset Allocation with Asymptotic Criteria
Authors: Karguine Slava
Published: August 2003

With the assumptions that asset returns follow a stochastic multi-factor process with time-varying conditional expectations and investments are linear functions of factors, we calculate asymptotic joint moments of the logarithm of investor's wealth and the factors. These formulas enable fast computation of a wide range of investment criteria. The results are illustrated by a numerical example that shows that the optimal portfolio rules are sensitive to the specification of the investment criterion.
Mean-Variance Hedging Under Additional Market Information
Authors: Thierbach F.
Published: August 2003

In this paper we analyze the mean-variance hedging approach in an incomplete market under the assumption of additional market information, which is represented by a given, finite set of observed prices of non-attainable contingent claims. Due to no-arbitrage arguments, our set of investment opportunities increases and the set of possible equivalent martingale measures shrinks. Therefore, we obtain a modified mean-variance hedging problem, which takes into account the observed additional market information. Solving this we obtain an explicit description of the optimal hedging strategy and an admissible, constrained variance-optimal signed martingale measure, that generates both the approximation price and the observed option prices.