bluuebunny/crossref_metadata_2025 huggingface dataset:
The incorporation of nucleoside analogs by human immunodeficiency virus type 1 reverse transcriptase decreases in the presence of polyamines
Authors: Bakhanashvili Mary , Rahav Galia
Published: September 2006

Nucleoside analogs (NAs) are an important class of anti‐retroviral compounds used against human immunodeficiency virus (HIV). We have analyzed the potential effect of polyamines on the incorporation of NAs during DNA synthesis by HIV type‐1 (HIV‐1) reverse transcriptase (RT). The polyamines exert the ability to decrease the incorporation of various dideoxynucleoside triphosphates (ddATP, ddTTP or ddCTP) with both RNA/DNA and DNA/DNA substrates in the following order: spermine > spermidine > putrescine. The reduction is a sequence‐independent effect, taking place at different sequence context. The results suggest that polyamines might affect the inhibition of reverse transcription by nucleoside analogs HIV‐1 RT directed.
Core Curriculum for the RN First Assistant
Authors: Welter C.J.
Published: September 2006

Core Curriculum for the RN First Assistant fourth edition Ruth E. Vaiden, ed 2005, 430 pages $45 member/$65 nonmember softcover
Simply Successful Surgery: A Holistic Approach to a Conventional Procedure
Authors: Shatto Nancy J.
Published: September 2006

Simply Successful Surgery: A Holistic Approach to a Conventional Procedure Linda Voyles 2005, 157 pages $15.95 softcover
African American Theatre
Authors: Krasner David , Anderson Lisa M. , George-Graves Nadine , Harris John Rogers , Lewis Barbara , Miller Henry , Young Harvey
Published: September 2006

David Krasner: In surveying contemporary London theatre, New York Times critic Ben Brantley reported that the Tricycle Theatre had

inaugurated a season of African-American plays with the commandingly titled but obscure Walk Hard, Talk Loud, a play by Abram Hill from the early1940's. Abram who? The name meant nothing to me, but Abram Hill (1910–1986) was a founder and director of the American Negro Theater in New York (1940–1951) and a playwright, it seems, of considerable verve.3

That Abram Hill and the American Negro Theatre—the most important black theatre company during the mid-twentieth century—has flown below the radar is indicative of how much work still needs to be accomplished.
Latin American(ist) Theatre History: Bridging the Divides
Authors: Graham-Jones Jean
Published: September 2006

In October 2004, I edited Theatre Journal's special issue on Latin American theatre. In addition to five essays on subjects ranging from sixteenth-century Amerindian performance to a twenty-first-century Mexican adaptation of an Irish play, that issue included a forum on the state of Latin American theatre and performance studies in the United States today. Even though the thirteen respondents resided, independently or as affiliates, in different disciplinary homes (theatre, performance, languages, and literature) and took multiple points of departure, a common thread ran throughout their comments: the need for the U.S. academy to study and teach the diversity that is known as Latin America.1 Tamara Underiner succinctly notes that “Latin America has never answered easily as an object of inquiry for theatre studies.”2 Indeed, studying Latin American theatre and performance poses very specific challenges: the region encompasses some twenty countries whose national borders obscure larger geographical, cultural, religious, political, and socioeconomic networks; a multiplicity of languages—European, dialectal, and indigenous to the hemisphere—are still spoken, written, and performed; and numerous intersecting histories extend back far beyond the five hundred years since the Europeans arrived and precipitated what today we euphemistically refer to as “contact.” Latin America does not terminate at the U.S.–Mexican border; thus although I'm cognizant of the attendant complications when including the U.S. latino/a communities in a discussion of Latin American theatre, the cultural network is such that I consider any arbitrary separation counter to the purposes of this reflection. Otherwise, how can we take into account the larger networks navigated by such U.S.-based playwrights as Guillermo Reyes (born in Chile but raised in the United States and the author of plays about Chilean history as well as specifically U.S. identities) or Ariel Dorfman (born in Argentina, raised in New York City and Santiago, Chile, now a professor at Duke, and author of English-language plays whose subject matter is frequently authoritarian Latin America)?
The State of Asian Theatre Studies in the American Academy
Authors: Sorgenfrei Carol Fisher
Published: September 2006

Being asked to write about the state of Asian theatre in the American academy makes me feel a little like Jean Genet explaining the origin of his play The Blacks: “One evening, an actor asked me to write a play for an all-black cast. But what exactly is a black? First of all, what's his color?”
Theatre Audiences, Redux
Authors: Bennett Susan
Published: September 2006

In retrospect, that Roland Barthes's insistence on “the death of the author” should have provoked an emergent interest in theatre audiences is hardly surprising. As, in literary studies, this brought about a new privilege for and investment in the reader, so too, in theatre and performance studies, there was an explicit recognition that what went on in the theatre was qualitatively and quantitatively more complicated and more exciting than the study of the playtext in the classroom. At the same time, the move to challenge a universalized (and thus male) viewing subject created new readings of the audience and new understandings of both individual and collective spectatorship across a range of subjectivities. So, Jill Dolan could argue that the “feminist spectator viewing such a representation is necessarily in the outsider's critical position.” Dolan continued:

She cannot find a comfortable way into the representation, since she finds herself, as a woman (and even more so, as a member of the working class, a lesbian, or a woman of color), excluded from its address. She sees in the performance frame representatives of her gender class with whom she might identify—if women are represented at all—acting passively before the specter of male authority.1
Building the Base
Authors: Herrington Joan
Published: September 2006

In the February 2005 issue of American Theatre, Ben Cameron considered impending season selection at theatres across the country and noted, “There are no magic bullets. God knows, I wish there were—especially in these times. … Even in the face of critical raves, standing ovations and a true sense of artistic pride, many have still fallen short of attendance goals.”2 Cameron explored a range of possible solutions to dwindling audiences: a season with no classics, or perhaps only classics; maybe opera, or A Christmas Carol, or the ever-popular Waiting for Godot. Indeed, the need to build audiences haunts most contemporary practitioners as we struggle to reestablish the place of theatre in the midst of its media sisters. It is a global issue, as noted in a column by Bhaskar Ghose in Frontline, a national Indian magazine: “Theatre needs to recapture its participative quality and density of human experience in order to woo the audience back from television and films. …”3 How then, do we build the base?
Intermediality, Infelicity, and Scholarship on the Slip
Authors: Schneider Rebecca
Published: September 2006

I am happy to take up this request to speak to the state of the field of performance studies, though I will be arguing here against the felicity of such a project. Performance studies, to my mind, is less “a thing done” than a set of questions asked, and the more performance studies keeps on the slip, remains diffuse, and resists congealing within delimited boundaries, the greater service it provides to our collective inquiries in the academy. This may be, oddly and even disturbingly, to argue for performance studies’ hollowness, its (in)capacity, its necessary infelicity—even, dare I suggest, its theatricality.
Music as Performance: Living in the Immaterial World
Authors: Auslander Philip
Published: September 2006

As a performance scholar and music lover, I find it strange that the fields of theatre and performance studies historically have been reluctant to engage with musical performance. Even as theatrical a musical form as opera is generally excluded from the history of theatre, on the grounds that “the predominant force in opera was the music rather than the words,” as Vera Mowry Roberts, my theatre history professor, puts the case.1 Roberts points to the nonliterary character of music as the reason for the exclusion; I speculate that the perception of music not only as nonliterary but, more broadly, as nonmimetic may seem to place it outside the realm of theatrical representation. While performance-oriented scholars spurn music, music-oriented scholars generally spurn performance. Traditional musicologists remain focused on the textual dimensions of musical compositions, whereas scholars who look at music from the perspective of cultural studies are generally more concerned with audience and reception than with the actual performance behavior of musicians.
Virtual Faith
Authors: Kubiak Anthony
Published: September 2006

The recent rubs and resistances within the various flows of religious thought and practice in American culture and politics have become near clichés. The impact of right-wing religions on government and cultural policies has been well noted, as have the concomitant attempts to keep religion of all kinds out of politics entirely. Meanwhile, the problematic status of Islam both locally and globally has become a continuous topic of debate, as have the debates over creationism and so-called intelligent design in American schools. These high-profile debates have in turn eclipsed the suspicions of academic leftist thought regarding religious questions of any sort, and this has in turn resulted in an entrenchment of theory—especially political theory—into a kind of religiosity of its own, while various forms of revivalism have signaled the mutation of faith into dogma, most recently the dogma of moderation. Each of these issues, apart from its intrinsic importance and currency, speaks to the practice of religion as a fundamentally philosophical problem of appearances that continues to emerge as a first cause of politics and of culture. The status of religion as a uniquely performative issue will, I think, occupy theorists over the coming years. Indeed, I suggest here that the thinking through of religion and spirituality will necessarily take place along the ontologic fault lines not just of performance but of theatre itself, and will come to delineate the important differences between performance and theatre. Finally, the reappraisal of religion as an ontologically charged theatricality will move into areas far afield from normative spirituality: cyberreligions and technoshamanism, chaos magic and the new alchemies, rave culture and other varieties of hyperinduced trance states.1 Although the focus in these newer forms of performance is almost exclusively on music, sound, and movement, the ultimate goal is the created intensity of a shared performative experience framed by theatrical perception: Artaud is the genius cited by nearly all of the authors of these phenomena. One larger suggestion here, in fact, is the moribund state of current theory, which sees dance culture (techno, hip-hop, electronica, rave), when it sees it at all, almost exclusively in cultural and political terms, ignoring the ecstatic, trance, and transformative aspects of DJ culture at large.2
The Avant-Garde and the Challenges of Resisting Parochialism
Authors: Sell Mike
Published: September 2006

My understanding of the avant-garde—and the state of avant-garde studies—was cast in stark relief by the social, political, military, and legal events that coincided with the period during which I was revising the manuscript of my first book. What those events were is no surprise: 9/11 and its various aftermaths. Many of this journal's readers have experienced a similar shift in perspective on their work—be it ethical, epistemological, or archival—leading them to reassess both their scholarly subjects and their methods in the face of what may well be a profound reconfiguration of power and knowledge.
An Isolationist Blacklist? Lillian Gish and the America First Committee
Authors: Fine Gary Alan , Shaw Rashida Z.
Published: September 2006

As it affected the performing arts community, the Red Scare has been examined in great detail.1 Taken together, these studies make clear that external political forces influence the hiring decisions of performing-arts organizations. From the 1930s to the 1950s figures affiliated with left-wing causes and groups found their careers stifled either temporarily or permanently because of their political beliefs. Although attention has focused primarily on institutional pressures from outside the industry on leftist artists, we describe an instance of pressure from within the industry on an artist whose politics were isolationist rather than progressive. In this research note, we present the case of Lillian Gish, describing how interventionists pressured her to distance herself from the isolationism that she had publicly embraced in the period immediately prior to the entrance of the United States in World War II. The attack on those described as “Nazi sympathizers” and their isolationist brethren during 1940–4 has come to be described as the “Brown Scare,”2 playing off the more widely known “Red Scares” of 1919–20 and 1947–54.
Reports and Surveys
Authors: Rudall B. H.
Published: September 2006

The Director of the Social Ecology Laboratory at the Universite Libre de Bruxelles has described the success of a 3 million European Union (EU) experiment for pest control. Dr. Jean-Louis Deneubourg believes that the EU funded initiative has many ramifications for more than just pest control.
Spectroscopic Characterization and Electrochemistry of Poly(ethylene oxide)‐Modified Myoglobin in Organic Solvents
Authors: Wiwatchaiwong Supranee , Nakamura Nobuhumi , Ohno Hiroyuki
Published: September 2006

Myoglobin (Mb) was chemically modified with activated poly(ethylene oxide) (PEO) (average molecular weight of 2000) to solubilize it in various organic solvents. UV‐vis, circular dichroism, and Raman spectroscopy were used to characterize the structure correlated with the electron‐transfer reactions of PEO‐modified Mb (PEO‐Mb). Spectroscopic data indicated changes in heme coordination geometry for PEO‐Mb in various organic solvents that are different from that in water. The Raman spectrum showed the characteristics of PEO‐Mb in PEO oligomer (average MW of 200) in the five‐coordinate high‐spin state, which facilitates fast electron‐transfer reactions between protein and the glassy carbon electrode. These results suggest heme environment effects on the properties of proteins in organic solvents.
Comparative performance of time‐invariant, long‐range and short‐range forecasting models on the earthquake catalogue of Greece
Authors: Console R. , Rhoades D. A. , Murru M. , Evison F. F. , Papadimitriou E. E. , Karakostas V. G.
Published: September 2006

Time‐invariant, long‐range, and short‐range forecasting models were fitted to the earthquake catalogue of Greece for magnitudes 4.0 and greater to optimize their ability to forecast events of magnitude 6.0 and greater in the period 1966–1980. The models considered were stationary spatially uniform and spatially varying Poisson models, a long‐range forecasting model based on the precursory scale increase phenomenon with every earthquake regarded as a precursor according to scale, and epidemic type short‐range forecasting models with spatially uniform and spatially varying spontaneous seismicity. Each of the models was then applied to the catalogue for 1981–2002, and their forecasting performance was compared using the log likelihood statistic. The long‐range forecasting model performed substantially better than the time‐invariant models, and the short‐range forecasting models performed substantially better again. The results show that the information value to be gained from modeling temporal and spatial variation of earthquake occurrence rate, at both long and short range, is much greater than can be gained from modeling spatial variation alone.
Observations of the sea surface by coherent L band radar at low grazing angles in a nearshore environment
Authors: Forget P. , Saillard M. , Broche P.
Published: September 2006

Coherent microwave L band signals have been collected in a Mediterranean coastal zone in horizontal transmit/horizontal receive (HH) and vertical transmit/vertical receive (VV) polarization modes at low grazing angles and under light to strong wind conditions. Doppler spectra have distinct morphologies depending on polarization mode and wind conditions. VV spectra and, only under light wind conditions, HH spectra present features that are consistent with an interaction process of Bragg type between electromagnetic waves and the sea surface, including the Doppler effects imparted by surface currents. At high wind, fast scatterers associated with greater velocities than Bragg velocity can be detected on HH spectra, depending on the direction of propagation of long waves and not on wind direction, these directions being not necessarily the same in the coastal zone considered. For a given radar range the backscattered power in VV was found to be almost constant, which suggests saturation of the wave spectrum in the short‐wave range and isotropy of the short‐wave spectral energy in the downwind half plane. For vertical polarization the observed variations of the relative backscattering coefficient with grazing angle are supported by the slightly rough surface scattering theory, but the HH/VV polarization ratio is much greater than predicted by this theory. The data suggest that at low grazing angles, non‐Bragg scattering effects play a major role at horizontal polarization, especially in high‐wind–high‐wave conditions.
Effects of the Yellow Sea Warm Current on the winter temperature distribution in a numerical model
Authors: Ma Jian , Qiao Fangli , Xia Changshui , Kim Chang S.
Published: September 2006

The temperature distribution and circulation patterns in the Yellow Sea (YS) are examined by using a wave‐tide‐circulation coupled numerical model. This model sufficiently reproduces the variation of the warm tongue structure of the Yellow Sea Warm Current (YSWC) from the double branches flowing along the YS Trough and the western 60 m isobath in January to the single stream along the western temperature front in March. This is observed in both the long‐term monthly climatology and the satellite‐based sea surface temperature images in recent years. Examining the local heat balance in the numerical model during the entire cooling period, it is found that the YSWC has a very important influence on the YS warm tongue structure. Compared with the surface cooling, the influence of the advection is small in the coastal shallow area but large in the deep warm tongue area (up to 50% of the magnitude of heat flux). Although bathymetry is the essential factor which causes the temperature front, the YSWC is the key factor which positions, shapes, and maintains the warm tongue structure. This helps to affirm the existence of the YSWC, at least as a monthly mean flow. However, more high‐resolution current observations in deeper layers west of Cheju Island and the western fork of the YS Trough are needed to confirm the existence of the YSWC and its characteristic timescale in the real YS.
Floe formation in Arctic sea ice
Authors: Hopkins Mark A. , Thorndike Alan S.
Published: September 2006

The ice pack covering northern seas is composed of a mixture of thick ridged and rafted ice, undeformed ice, and open water. Ice motions determined from satellite remote sensing data show that deformation of the pack takes place along the boundary of large floes. Eulerian continuum sea ice models can simulate this behavior to a degree by capturing the localization of gridded ice strength in some average sense. However, using a discontinuous Lagrangian approach that explicitly models ice floes and the interactions between them, it is possible to simulate both the fracture process that creates floe boundaries and the continued deformation along those floe boundaries. We have developed a granular model of the central Arctic ice pack that consists of thousands of individual grains that can freeze together, fracture apart, and interact through ridging. Accelerations produced by passing weather patterns and sustained quasi‐steady deformation cause the model pack to fracture apart into floes composed of one or more grains. When the ice pack is nonuniformly accelerating due to passage of a weather pattern, simulations show that the factors that influence the size of the floes are the tensile strength of the joints between grains, the gradient of the wind field, and the average size of the individual grains. During sustained deformation the pack continues to deform along existing floe boundaries while stresses build and further fracture takes place. In quiet areas of the basin, fractures refreeze. To explore the fracture process during sustained deformation, we run 24‐hour basin scale simulations at resolutions from 2.8 km to 14 km. At the end of each simulation we construct a distribution of floe areas. The cumulative distribution of floes at the large end of the distribution is approximately the same at each resolution. As we increase the resolution from 14 km to 2.8 km, the damage zones between large floes become more localized. A log‐log plot of the cumulative floe size distributions obtained from the simulations appears linear over several orders of magnitude.
Time series and recurrence interval models to predict the vulnerability of streams to episodic acidification in Shenandoah National Park, Virginia
Authors: Deviney Frank A. , Rice Karen C. , Hornberger George M.
Published: September 2006

Acid rain affects headwater streams by temporarily reducing the acid‐neutralizing capacity (ANC) of the water, a process termed episodic acidification. The increase in acidic components in stream water can have deleterious effects on the aquatic biota. Although acidic deposition is uniform across Shenandoah National Park (SNP) in north central Virginia, the stream water quality response during rain events varies substantially. This response is a function of the catchment's underlying geology and topography. Geologic and topographic data for SNP's 231 catchments are readily available; however, long‐term measurements (tens of years) of ANC and accompanying discharge are not and would be prohibitively expensive to collect. Transfer function time series models were developed to predict hourly ANC from discharge for five SNP catchments with long‐term water‐quality and discharge records. Hourly ANC predictions over short time periods (≤1 week) were averaged, and distributions of the recurrence intervals of annual water‐year minimum ANC values were model‐simulated for periods of 6, 24, 72, and 168 hours. The distributions were extrapolated to the rest of the SNP catchments on the basis of catchment geology and topography. On the basis of the models, large numbers of SNP streams have 6‐ to 168‐hour periods of low‐ANC values, which may stress resident fish populations. Smaller catchments are more vulnerable to episodic acidification than larger catchments underlain by the same bedrock. Catchments with similar topography and size are more vulnerable if underlain by less basaltic/carbonate bedrock. Many catchments are predicted to have successive years of low‐ANC values potentially sufficient to extirpate some species.
Magnetic reconnection at the heliospheric current sheet and the formation of closed magnetic field lines in the solar wind
Authors: Gosling J.T. , McComas D.J. , Skoug R.M. , Smith C.W.
Published: September 2006

We have identified a sunward‐directed reconnection exhaust in the solar wind at a crossing of the heliospheric current sheet, HCS, by the ACE spacecraft. The exhaust was embedded within an interval of counterstreaming suprathermal electron strahls that provides direct evidence that reconnection produced closed (i.e., doubly connected to the Sun) magnetic field lines sunward of the reconnection site. We suggest that local, quasi‐stationary reconnection at the HCS may, in general, be an important source of closed magnetic field lines often observed in the vicinity of the HCS.
An experimental investigation of wave measurements using a dual‐beam interferometer: Gulf Stream as a surface wave guide
Authors: Hwang Paul A. , Toporkov Jakov V. , Sletten Mark A. , Lamb Douglas , Perkovic Dragana
Published: September 2006

A dual‐beam interferometric synthetic aperture radar measures remotely two radial components of the ocean surface current from a single flight pass. Combining two passes over the same area, all three orthogonal components of the surface velocity can be retrieved. An experiment is conducted near the Gulf Stream (GS) boundary. A sharp change of the surface velocity of about 1 m/s over a 500 m lateral distance is measured. The wind and wave condition is dominated by a 14‐s swell system and low wind velocity. The wave variance inside GS is about twice the wave variance outside the GS in the present data set. The difference in the wave variance is considerably higher than that can be expected from wave‐current interaction. An ocean current system with strong shears such as the GS is a wave guide and can trap waves with the right combinations of wavelengths and propagation directions. Numerical calculations suggest that the wave properties of the data set may satisfy the conditions of wave trapping by the GS. The standing wave pattern on the GS side of the sharp velocity front, indicative of the long swell bouncing off the current front, also offers support for the wave guide hypothesis. In this respect, the Gulf Stream can be considered the nature's hydraulic breakwater that can attenuate about 50% of the incident wave energy generated by storms. Its role in protecting the U.S. coastlines in the Atlantic Ocean cannot be overstated.
Aberration control in quantitative imaging of botanical specimens by multidimensional fluorescence microscopy
Authors: WHITE N. S. , ERRINGTON R. J. , FRICKER M. D. , WOOD J. L.
Published: September 2006

Three dimensional (3‐D) fluorescence microscopes, including conventional instruments with digital deblurring, confocal systems and two‐photon excitation, all exhibit monochromatic and chromatic aberrations. A simple Gaussian model of the aberrated point spread function and optical field for each instrument illustrates spatial distortions and blurring and some unique attenuation effects in confocal and two‐photon microscopy. These properties depend on the manner in which illumination and detection combine to give the overall microscope performance and highlight the importance of both optics and sample aberrations; the specimen must be considered as an optical component of the integrated imaging system.

Axial focus distortion, from refractive index boundaries at the sample, can be accurately modelled by a geometric ray tracing programme, considering weighted components across the entire objective lens working NA. The modal z‐focus error, rather than the average of all weighted rays, agrees closely with empirical measurements of axial focus position from test samples. This agreement is particularly close for confocal measurements when NA4 weighting is used in the model calculations, but the situation is more complex for samples with non‐planar refractive boundaries.

Calibration of axial attenuation in a botanical sample, arising from the combination of optical sectioning with specimen‐induced spatial distortions and blurring, is possible using an in situ fluorescence sea within a permeabilized preparation. Parametric descriptions of attenuation can be obtained through the guard cell complex of Commelina communis leaf epidermis. Improved images of the 3‐D morphology of stomatal guard cells are then obtained by digital correction of attenuation and spatial distortion. Calibrations can be routinely used to correct experimental data by integration with a structured image file format.
Physiological Responses of Forest Trees to Heat and Drought
Authors: Rennenberg H. , Loreto F. , Polle A. , Brilli F. , Fares S. , Beniwal R. S. , Gessler A.
Published: September 2006

Abstract:The heat wave of summer 2003 was the largest and the most persistent ever experienced in Central Europe and has fuelled concern about the effects of climate change on European ecosystems. Since forests constitute the most important European ecosystems, in this review article we assess current knowledge on the effects of heat and drought on key metabolic processes for growth and productivity of forest trees. In particular, the general consequences of heat and drought on (1) photosynthesis and respiration at the cellular and community level, and (2) on nutrient uptake, partitioning and competition for nutrients are summarized. The latter are a major sink for photosynthetic energy and, therefore, are indirectly but strongly connected to the performance of photosynthesis. In addition, the interaction of heat and drought with stress compensation mechanisms and emission of biogenic volatile organic compounds (BVOC) are discussed, since these processes are directly connected to carbon metabolism. Effects on the emission of BVOC are also included because they constitute an important feedback mechanism on ozone formation and, thus, on atmospheric pollution. As far as available, data collected during the 2003 heat wave are included and discussed.
Ecophysiological Traits Associated with Drought in Mediterranean Tree Seedlings: Individual Responses versus Interspecific Trends in Eleven Species
Authors: Valladares F. , Sánchez‐Gómez D.
Published: September 2006

Abstract: Species differ regarding their drought tolerance and individuals of a given species can modify their morphology and physiology in response to drought. However, since evolutionary and ecological selective pressures differ, individual and interspecific responses to drought might not match. We determined summer survival and a number of ecophysiological variables in two factorial experiments with seedlings of eleven tree species present in Mediterranean ecosystems, grown under slowly imposed water stress and control conditions. Plants experiencing drought exhibited reduced growth, low specific leaf area, chlorophyll content, and photosynthetic rate when compared to the controls, and species‐specific drought tolerance was associated with an analogous set of trait values. However, while species with high leaf area ratio and shoot‐root ratio exhibited greater drought tolerance, drought induced the reversed response within species. Contrary to expectations, water use efficiency was lower in drought‐tolerant species and decreased in water‐stressed individuals compared to the control plants. There was a distinctive phylogenetic signal in the functional grouping of species, with oaks, pines, and other genera being clearly different from each other in their drought tolerance and in their functional responses to drought. However, all relationships between ecophysiological variables and drought tolerance were significant after accounting for phylogenetic effects, with the exception of the relationship between drought tolerance and photochemical efficiency. Our results show that drought tolerance is not achieved by a single combination of trait values, and that even though evolutionary processes and individual responses tend to render similar results in terms of functional traits associated with drought, they do not necessarily match.
Disintegration of the Prolamellar Body Structure at High Concentrations of Hg2+
Authors: Solymosi K. , Myśliwa‐Kurdziel B. , Bóka K. , Strzałka K. , Böddi B.
Published: September 2006

Abstract:The effects of high concentrations of Hg2+(10‐2M and 10‐3M) were investigated on the ultrastructure and on the light‐induced transformation of isolated prolamellar bodies (PLBs) of dark‐grown wheat leaves. Our earlier work on wheat leaf homogenates (Solymosi et al. [2004], Plant Biology 6, 358 ‐ 368) showed that, depending on the concentration, Hg2+reacts with protochlorophyllide, NADPH and the NADPH: protochlorophyllide oxidoreductase (POR, EC 1.3.1.33) enzyme and induces disaggregation of the macrodomain structure of this latter. Spectroscopic analyses confirmed that 15 min incubation with 10‐2M Hg2+at 4°C completely inhibited the activity of POR also in isolated PLBs. Ultrastructural investigations revealed the loosening of the PLB structure in the Hg2+‐treated sample, i.e., intensive vesicle formation on the surface of the PLB membranes. The hexagonal geometry of the inner lattice was not disturbed, however, the unit cell size significantly increased. The disruption of the PLB membranes upon irradiation was studied after 40 min incubation with 10‐3M Hg2+at 4°C and a subsequent irradiation for 40 min at 20°C. Equimolar concentrations (10‐3M) of NADPH and Hg2+were added to the samples 10 min prior or after the addition of Hg2+. Our results suggest that Hg2+accelerates the disruption of the PLB membranes and that NADPH can only partially prevent this process. These membrane transformations were similar to those observed in the initial steps of the Shibata shift of control samples.
Abscisic Acid Stimulates the Expression of Two Isoforms of Plasma Membrane Ca2+‐ATPase in Arabidopsis thaliana Seedlings
Authors: Cerana M. , Bonza M. C. , Harris R. , Sanders D. , de Michelis M. I.
Published: September 2006

Abstract: At‐ACA8 and At‐ACA9 are two plasma membrane (PM) Ca2+‐ATPases of Arabidopsis thaliana. In this article the expression of At‐ACA8, At‐ACA9, and of At‐ACA10, a third isoform of Ca2+‐ATPase closely related to PM Ca2+‐ATPases, was analysed and the effect of the hormone abscisic acid (ABA) on the expression level of PM Ca2+‐ATPase specific transcripts was investigated. In adult plants of A. thaliana, At‐ACA8 and At‐ACA10 are expressed in all organs considered whereas At‐ACA9 is expressed only in flowers. All isoforms of PM Ca2+‐ATPases can be detected in young seedlings but the amount of At‐ACA9 mRNA is much lower than those of At‐ACA8 and At‐ACA10. ABA markedly and rapidly stimulates the expression of both At‐ACA8 and At‐ACA9 genes in young seedlings but not that of At‐ACA10. ABA also increases the level of At‐ACA8 protein at the PM, suggesting a role for PM Ca2+‐ATPases in ABA signalling.
Chlorophyll a Fluorescence Imaging of Ozone‐Stressed Brassica napus L. Plants Differing in Glucosinolate Concentrations
Authors: Gielen B. , Vandermeiren K. , Horemans N. , D'Haese D. , Serneels R. , Valcke R.
Published: September 2006

Abstract: Brassicaceae are characterised by glucosinolates (GS), which appear to be involved not only in biotic but also in abiotic stress responses of plants. We investigated the effect of O3 stress on leaf GS concentrations in two lines of Brassica napus L., differing in GS content. Ozone fumigation decreased GS concentrations in leaves of B. napus of one line. In control conditions, chlorophyll content, rates of saturating photosynthesis, and quantum yield of photosystem 2 differed between the two Brassica lines, but differences were smaller in O3□stress conditions, suggesting that the relationship between leaf GS concentration and sensitivity to abiotic stress merits further research. In agreement with other ecophysiological measurements, chlorophyll fluorescence imaging clearly distinguished both lines and in some cases also treatments. A method for analysis of fluorescence images accounting for the two‐dimensional leaf heterogeneity is presented.
Evaluation of a Non‐Targeted “Omic” Approach in the Safety Assessment of Genetically Modified Plants
Authors: Metzdorff S. B. , Kok E. J. , Knuthsen P. , Pedersen J.
Published: September 2006

Abstract: Genetically modified plants must be approved before release in the European Union, and the approval is generally based upon a comparison of various characteristics between the transgenic plant and a conventional counterpart. As a case study, focusing on safety assessment of genetically modified plants, we here report the development and characterisation of six independently transformed Arabidopsis thaliana lines modified in the flavonoid biosynthesis. Analyses of integration events and comparative analysis for characterisation of the intended effects were performed by PCR, quantitative Real‐time PCR, and High Performance Liquid Chromatography. Analysis by cDNA microarray was used as a non‐targeted approach for the identification of potential unintended effects caused by the transformation. The results revealed that, although the transgenic lines possessed different types of integration events, no unintended effects were identified. However, we found that the majority of genes showing differential expression were identified as stress‐related genes and that environmental conditions had a large impact on the expression of several genes, proteins, and metabolites. We suggest that the microarray approach has the potential to become a useful tool for screening of unintended effects, but state that it is crucial to have substantial information on the natural variation in traditional crops in order to be able to interpret “omics” data correctly within the framework of food safety assessment strategies of novel plant varieties, including genetically modified plant varieties.
Cadmium Induces Changes in Sucrose Partitioning, Invertase Activities, and Membrane Functionality in Roots of Rangpur Lime (Citrus limonia L. Osbeck)
Authors: Podazza G. , Rosa M. , González J. A. , Hilal M. , Prado F. E.
Published: September 2006

Abstract: Cadmium (Cd) uptake effects on sucrose content, invertase activities, and plasma membrane functionality were investigated in Rangpur lime roots (Citrus limonia L. Osbeck). Cadmium accumulation was significant in roots but not in shoots and leaves. Cadmium produced significant reduction in roots DW and increment in WC. Leaves and shoots did not show significant differences on both parameters. Sucrose content was higher in control roots than in Cd‐exposed ones. Apoplastic sucrose content was much higher in Cd‐exposed roots than in control ones. Cd‐exposed roots showed a significant decrease in both cell wall‐bound and cytoplasmic (neutral) invertase activities; while the vacuolar isoform did not show any change. Alterations in lipid composition and membrane fluidity of Cd‐exposed roots were also observed. In Cd‐exposed roots phospholipid and glycolipid contents decreased about 50 %, while sterols content was reduced about 22 %. Proton extrusion was inhibited by Cd. Lipid peroxidation and proton extrusion inhibition were also detected by histochemical analysis. This work's findings demonstrate that Cd affects sucrose partitioning and invertase activities in apoplastic and symplastic regions in Rangpur lime roots as well as the plasma membrane functionality and H+‐ATPase activity.
Plant Aquaporins: New Perspectives on Water and Nutrient Uptake in Saline Environment
Authors: del Martínez‐Ballesta M. C. , Silva C. , López‐Berenguer C. , Cabañero F. J. , Carvajal M.
Published: September 2006

Abstract:The mechanisms of salt stress and tolerance have been targets for genetic engineering, focusing on ion transport and compartmentation, synthesis of compatible solutes (osmolytes and osmoprotectants) and oxidative protection. In this review, we consider the integrated response to salinity with respect to water uptake, involving aquaporin functionality. Therefore, we have concentrated on how salinity can be alleviated, in part, if a perfect knowledge of water uptake and transport for each particular crop and set of conditions is available.
Light is Essential for Degradation of Ribulose‐1,5‐Bisphosphate Carboxylase‐Oxygenase Large Subunit During Sudden Death Syndrome Development in Soybean
Authors: Ji J. , Scott M. P. , Bhattacharyya M. K.
Published: September 2006

Abstract: Fusarium solani f. sp. glycines (Fsg) has been reported to produce at least two phytotoxins. Cell‐free Fsg culture filtrates containing phytotoxins have been shown to develop foliar sudden death syndrome (SDS) in soybean. We have investigated the changes in protein profiles of diseased leaves caused by cell‐free Fsg culture filtrates prepared from Fsg isolates. Two‐dimensional sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (PAGE) was conducted to investigate the protein profiles of diseased and healthy leaves. An approximately 55 kDa protein was found to be absent in diseased leaves. Matrix‐assisted laser desorption‐ionization time‐of‐flight mass spectrometric analyses and a database search revealed that the missing protein is the ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) large subunit, which is involved in carbon assimilation and photorespiration. This result was confirmed by Western blot experiments. We have shown that light is essential for disappearance of the Rubisco large subunit initiated by cell‐free Fsg culture filtrates. The disappearance of the protein is fairly rapid and occurs within 24 h, presumably due to degradation. Cell‐free, Fsg culture‐induced degradation of the Rubisco large subunit was accompanied by accumulation of reactive oxygen species under light conditions. Terminal deoxynucleotidyl transferase‐mediated nick end labelling experiments suggested that programmed cell death was initiated in leaves of seedlings fed with cell‐free Fsg culture filtrates. These results suggest that, in the presence of light, Fsg culture filtrates containing phytotoxins cause degradation of the Rubisco large subunit and accumulation of free radicals and, thereby, initiate programmed cell death leading to foliar SDS development in soybean.
Construction of a Primary RH Panel of Italian Ryegrass Genome via UV‐Induced Protoplast Fusion
Authors: Cheng A. , Cui H. , Xia G.
Published: September 2006

Abstract: Symmetric and asymmetric somatic hybrids were produced via protoplast fusion between common wheat (Triticum aestivum L.) cv. “Jinan 177” and Italian ryegrass (Lolium multiflorum Lam.). The ryegrass without or with UV irradiation was used as a donor, providing a small amount of chromatin. In these somatic hybrids, most ryegrass chromosomes have been confirmed preferential elimination and the somatic hybrid calli and plants showed wheat‐like morphology. Some of the hybrid lines were used for the analysis of distribution and heredity of donor DNA in the hybrid genome and the possibility of establishing a radiation hybrid (RH) panel of the ryegrass in the present experiment. These hybrids, subcultured for two and three years, retained the ryegrass DNA examined by RFLP and GISH analysis, respectively. Distribution of the ryegrass DNA in the wheat genomes of 20 single‐cell individuals, randomly selected from hybrid cell lines produced, were analyzed by 21 ryegrass genome specific SSR markers. The average frequencies of molecular marker retention in symmetric hybrid lines (UV 0), as well as asymmetric hybrid lines from UV 30 s and 1 min were 10.88, 15.48 and 33.86, respectively. It was suggested that the UV dose increased the introgression of donor DNA into wheat genome. The ryegrass SSR fragments in most asymmetric hybrid cell lines remained stable over a period of 2 – 3 years. This revealed that those asymmetric somatic hybrids are suitable for the introgression of ryegrass DNA into wheat, and for RH panel and RH mapping.
Redox Regulation and Flower Development: A Novel Function for Glutaredoxins
Authors: Xing S. , Lauri A. , Zachgo S.
Published: September 2006

Abstract: Glutaredoxins (GRXs) are small, ubiquitous oxidoreductases that have been intensively studied in E. coli, yeast and humans. They are involved in a large variety of cellular processes and exert a crucial function in the response to oxidative stress. GRXs can reduce disulfides by way of conserved cysteines, located in conserved active site motifs. As in E. coli, yeast, and humans, GRXs with active sites of the CPYC and CGFS type are also found in lower and higher plants, however, little has been known about their function. Surprisingly, 21 GRXs from Arabidopsis thaliana contain a novel, plant‐specific CC type motif. Lately, information on the function of CC type GRXs and redox regulation, in general, is accumulating. This review focuses on recent findings indicating that GRXs, glutathione and redox regulation, in general, seem to be involved in different processes of development, so far, namely in the formation of the flower. Recent advances in EST and genome sequencing projects allowed searching for the presence of the three different types of the GRX subclasses in other evolutionary informative plant species. A comparison of the GRX subclass composition from Physcomitrella, Pinus, Oryza, Populus, and Arabidopsis is presented. This analysis revealed that only two CC type GRXs exist in the bryophyte Physcomitrella and that the CC type GRXs group expanded during the evolution of land plants. The existence of a large CC type subclass in angiosperms supports the assumption that their capability to modify target protein activity posttranslationally has been integrated into crucial plant specific processes involved in higher plant development.
Deep acceptor states in ZnO single crystals
Authors: von Wenckstern H. , Pickenhain R. , Schmidt H. , Brandt M. , Biehne G. , Lorenz M. , Grundmann M. , Brauer G.
Published: September 2006

The authors report the observation of both acceptor- and donorlike defects in ZnO by deep level transient spectroscopy. The observation is facilitated by using a p-n junction allowing the injection of holes and electrons. The junction is realized by implanting a n-conducting ZnO wafer grown by pressurized melt growth with nitrogen ions. The authors found the commonly observed donorlike defects E1 and E3 and two acceptorlike defects A2 and A3, as well as a broad acceptorlike defect band. The thermal activation energies of A2 and A3, were determined to be about 150 and 280meV, respectively.
Design and performance of a beetle-type double-tip scanning tunneling microscope
Authors: Jaschinsky Philipp , Coenen Peter , Pirug Gerhard , Voigtländer Bert
Published: September 2006

A combination of a double-tip scanning tunneling microscope with a scanning electron microscope in ultrahigh vacuum environment is presented. The compact beetle-type design made it possible to integrate two independently driven scanning tunneling microscopes in a small space. Moreover, an additional level for coarse movement allows the decoupling of the translation and approach of the tunneling tip. The position of the two tips can be controlled from the millimeter scale down to 50nm with the help of an add-on electron microscope. The instrument is capable of atomic resolution imaging with each tip.
Field-electron emission at 300K in self-assembled arrays of silicon nanowires
Authors: Klimovskaya Alla I. , Litvin Yurii M. , Moklyak Yuliya Yu. , Dadykin Alex A. , Kamins Ted I. , Sharma Shashank
Published: September 2006

Dense ensembles of silicon nanowires were prepared by metal-catalyzed chemical vapor deposition on silicon substrates. Some of these ensembles were doped with phosphorus during growth. The nanowires were characterized using scanning electron microscopy, x-ray diffraction, and mass spectroscopy. Field emission of electrons from these structures was studied at room temperature in ultrahigh vacuum. The measurements were carried out using a parallel-plate diode cell. At high applied fields, the current-voltage characteristics deviate from the Fowler-Nordheim law and exhibit a stepwise increase of the current with increasing voltage at 300K.