bluuebunny/crossref_metadata_2025 huggingface dataset:
Thinking without knowing – Child psychoanalytic psychotherapy in the UK and evidence‐based practice
Authors: Rous Elizabeth , Clark Andrew
Published: February 2011

Background  Child psychoanalytic psychotherapy has been criticized for its reluctance to embrace evidence‐based practice. This study aims to explore the historical narrative of a sample of child psychoanalytic psychotherapists about progress in developing the evidence base.

Methods  Fourteen psychotherapists were interviewed and the transcripts analysed for common themes about evidence‐based practice.

Results  Child psychoanalytic psychotherapists were generally positive about developing evidence‐based practice but had reservations about the narrowness of hierarchies used by commissioners to assess evidence.

Conclusion  The child psychoanalytical psychotherapists interviewed for this study recognized the need to promote evidence‐based practice, in particular, to inform commissioners of Child Mental Health Services.
Collective learning, change and improvement in health care: trialling a facilitated learning initiative with general practice teams
Authors: Bunniss Suzanne , Gray Francesca , Kelly Diane
Published: February 2011

Rationale, aims and objectives  Many patients, families, health care professionals and politicians desire for quality improvement within the UK National Health Service. One way to achieve this change is for health care teams to work and learn together more effectively. This research aimed to design and trial a facilitated learning programme with the aim of supporting general practice teams in fostering the characteristics of learning organizations.

Methods  This is an action research study. Qualitative data were captured during and after the trial from 40 participants in two multi‐professional general practice teams within different Scottish health boards. Data were gathered using observations, semi‐structured interviews and written learning notes.

Results  Taking part in the LPP was a positive experience of learning together as a practice and enhanced communication within the team was a particular outcome. External facilitation helped provide focus and reduce inter‐professional barriers. Teams found working in small, mixed role discussion groups particularly valuable in understanding each others' perspectives. The active learning style of the LPP could be daunting at times but teams valued the chance to identify their own quality improvement goals. Teams introduced a number of changes to improve the quality of care within their practice as a result of their participation.

Conclusion  This trial of the learning practice programme shows that, with facilitation and the appropriate input of resources, general practice teams can successfully apply learning organization principles to produce quality improvement outcomes. The study also demonstrates the value of action research in researching iterative change over time.
Adaptive evolution of the Populus tremula photoperiod pathway
Authors: HALL DAVID , MA XIAO‐FEI , INGVARSSON PÄR K.
Published: February 2011

Perennial plants monitor seasonal changes through changes in environmental conditions such as the quantity and quality of light and genes in the photoperiodic pathway are known to be involved in controlling these processes. Here, we examine 25 of genes from the photoperiod pathway in Populus tremula (Salicaceae) for signatures of adaptive evolution. Overall, levels of synonymous polymorphism in the 25 genes are lower than at control loci selected randomly from the genome. This appears primarily to be caused by lower levels of synonymous polymorphism in genes associated with the circadian clock. Natural selection appears to play an important role in shaping protein evolution at several of the genes in the photoperiod pathways, which is highlighted by the fact that approximately 40% of the genes from the photoperiod pathway have estimates of selection on nonsynonymous polymorphisms that are significantly different from zero. A surprising observation we make is that circadian clock‐associated genes appear to be over‐represented among the genes showing elevated rates of protein evolution; seven genes are evolving under positive selection and all but one of these genes are involved in the circadian clock of Populus.
Transgenic poplars with reduced lignin show impaired xylem conductivity, growth efficiency and survival
Authors: VOELKER STEVEN L. , LACHENBRUCH BARBARA , MEINZER FREDERICK C. , KITIN PETER , STRAUSS STEVEN H.
Published: February 2011

We studied xylem anatomy and hydraulic architecture in 14 transgenic insertion events and a control line of hybrid poplar (Populus spp.) that varied in lignin content. Transgenic events had different levels of down‐regulation of two genes encoding 4‐coumarate:coenzyme A ligase (4CL). Two‐year‐old trees were characterized after growing either as free‐standing trees in the field or as supported by stakes in a greenhouse. In free‐standing trees, a 20 to 40% reduction in lignin content was associated with increased xylem vulnerability to embolism, shoot dieback and mortality. In staked trees, the decreased biomechanical demands on the xylem was associated with increases in the leaf area to sapwood area ratio and wood specific conductivity (ks), and with decreased leaf‐specific conductivity (kl). These shifts in hydraulic architecture suggest that the bending stresses perceived during growth can affect traits important for xylem water transport. Severe 4CL‐downregulation resulted in the patchy formation of discoloured, brown wood with irregular vessels in which water transport was strongly impeded. These severely 4CL‐downregulated trees had significantly lower growth efficiency (biomass/leaf area). These results underscore the necessity of adequate lignification for mechanical support of the stem, water transport, tree growth and survival.
Circadian photosynthetic reductant flow in the dinoflagellate Lingulodinium is limited by carbon availability
Authors: MACKENZIE TYLER D. B. , MORSE DAVID
Published: February 2011

Circadian rhythms are the observed outputs of endogenous daily clocks and are thought to provide a selective advantage to cells adapted to daily light/dark cycles. However, the biochemical links between the clock and the overt rhythms in cell physiology are generally not known. Here, we examine the circadian rhythm in O2 evolution by cultures of the dinoflagellate Lingulodinium, a rhythm previously ascribed to rhythmic electron flow through photosystem II. We find that O2 evolution rates increase when CO2 concentrations are increased, either following addition of DIC or a rapid decrease in culture pH. In medium containing only nitrate as an electron acceptor, O2 evolution rates mirror the circadian rhythm of nitrate reductase activity in the cells. Furthermore, competition between photosynthetic electron flow to carbon and to nitrate varies in its relative efficiency through the day–night cycle. We also find, using simultaneous and continuous monitoring of pH and O2 evolution rates over several days, that while culture pH is normally rhythmic, circadian changes in rates of O2 evolution depend not on the external pH but on levels of internal electron acceptors. We propose that the photosynthetic electron transport rhythm in Lingulodinium is driven by the availability of a reductant sink.
Proton‐coupled high‐affinity phosphate transport revealed from heterologous characterization in Xenopus of barley‐root plasma membrane transporter, HvPHT1;1
Authors: PREUSS CHRISTIAN P. , HUANG CHUN Y. , TYERMAN STEPHEN D.
Published: February 2011

High‐affinity phosphate transporters mediate uptake of inorganic phosphate (Pi) from soil solution under low Pi conditions. The electrophysiological properties of any plant high‐affinity Pi transporter have not been described yet. Here, we report the detailed characterization of electrophysiological properties of the barley Pi transporter, HvPHT1;1 in Xenopus laevis oocytes. A very low Km value (1.9 µm) for phosphate transport was observed in HvPHT1;1, which falls within the concentration range observed for barley roots. Inward currents at negative membrane potentials were identified as nH+:Pi‐ (n > 1) co‐transport based on simultaneous Pi radiotracer uptake, oocyte voltage clamping and pH dependence. HvPHT1;1 showed preferential selectivity for Pi and arsenate, but no transport of the other oxyanions SO42− and NO3‐. In addition, HvPHT1;1 locates to the plasma membrane when expressed in onion (Allium cepa L.) epidermal cells, and is highly expressed in root segments with dense hairs. The electrophysiological properties, plasma membrane localization and cell‐specific expression pattern of HvPHT1;1 support its role in the uptake of Pi under low Pi conditions.
Hydraulic conductivity of red oak (Quercus rubra L.) leaf tissue does not respond to light
Authors: ROCKWELL F. E. , HOLBROOK N. M. , ZWIENIECKI M. A.
Published: February 2011

The permeability of leaf tissue to water has been reported to increase under illumination, a response reputed to involve aquaporins. We studied this ‘light response’ in red oak (Quercus rubra L.), the species in which the phenomenon was first detected during measurements of leaf hydraulic conductance with the high‐pressure flow meter (HPFM). In our HPFM measurements, we found that pre‐conditioning leaves in darkness was not sufficient to bring them to their minimum conductance, which was attained only after an hour of submersion and pressurization. However, pre‐conditioning leaves under anoxic conditions resulted in an immediate reduction in conductance. Leaves light‐ and dark‐acclimated while on the tree showed no differences in the time course of HPFM measurement under illumination. We also studied the effect of light level and anoxia on rehydration kinetics, finding that anoxia slowed rehydration, but light had no effect either in the lab (rehydration under low light, high humidity) or on the tree (acclimation under high light, 10 min of dark prior to rehydration). We conclude that the declines in conductance observed in the HPFM must involve a resistance downstream of the extracellular air space, and that in red oak the hydraulic conductivity of leaf tissue is insensitive to light.
Foliar and soil δ15N values reveal increased nitrogen partitioning among species in diverse grassland communities
Authors: GUBSCH MARLÉN , ROSCHER CHRISTIANE , GLEIXNER GERD , HABEKOST MAIKE , LIPOWSKY ANNETT , SCHMID BERNHARD , SCHULZE ERNST‐DETLEF , STEINBEISS SIBYLLE , BUCHMANN NINA
Published: February 2011

Plant and soil nitrogen isotope ratios (δ15N) were studied in experimental grassland plots of varying species richness. We hypothesized that partitioning of different sources of soil nitrogen among four plant functional groups (legumes, grasses, small herbs, tall herbs) should increase with diversity. Four years after sowing, all soils were depleted in 15N in the top 5 cm whereas in non‐legume plots soils were enriched in 15N at 5–25 cm depth. Decreasing foliar δ15N and Δδ15N (= foliar δ15N − soil δ15N) values in legumes indicated increasing symbiotic N2 fixation with increasing diversity. In grasses, foliar Δδ15N also decreased with increasing diversity suggesting enhanced uptake of N depleted in 15N. Foliar Δδ15N values of small and tall herbs were unaffected by diversity. Foliar Δδ15N values of grasses were also reduced in plots containing legumes, indicating direct use of legume‐derived N depleted in 15N. Increased foliar N concentrations of tall and small herbs in plots containing legumes without reduced foliar δ15N indicated that these species obtained additional mineral soil N that was not consumed by legumes. These functional group and species specific shifts in the uptake of different N sources with increasing diversity indicate complementary resource use in diverse communities.
The water–water cycle in leaves is not a major alternative electron sink for dissipation of excess excitation energy when CO2 assimilation is restricted
Authors: DRIEVER STEVEN M. , BAKER NEIL R.
Published: February 2011

Electron flux from water via photosystem II (PSII) and PSI to oxygen (water–water cycle) may provide a mechanism for dissipation of excess excitation energy in leaves when CO2 assimilation is restricted. Mass spectrometry was used to measure O2 uptake and evolution together with CO2 uptake in leaves of French bean and maize at CO2 concentrations saturating for photosynthesis and the CO2 compensation point. In French bean at high CO2 and low O2 concentrations no significant water–water cycle activity was observed. At the CO2 compensation point and 3% O2 a low rate of water–water cycle activity was observed, which accounted for 30% of the linear electron flux from water. In maize leaves negligible water–water cycle activity was detected at the compensation point. During induction of photosynthesis in maize linear electron flux was considerably greater than CO2 assimilation, but no significant water–water cycle activity was detected. Miscanthus × giganteus grown at chilling temperature also exhibited rates of linear electron transport considerably in excess of CO2 assimilation; however, no significant water–water cycle activity was detected. Clearly the water–water cycle can operate in leaves under some conditions, but it does not act as a major sink for excess excitation energy when CO2 assimilation is restricted.
Toward the mechanism of NH4+ sensitivity mediated by Arabidopsis GDP‐mannose pyrophosphorylase
Authors: KEMPINSKI CHASE F. , HAFFAR RAWAA , BARTH CARINA
Published: February 2011

The ascorbic acid (AA)‐deficient Arabidopsis thaliana mutant vtc1‐1, which is defective in GDP‐mannose pyrophosphorylase (GMPase), exhibits conditional hypersensitivity to ammonium (NH4+), a phenomenon that is independent of AA deficiency. As GMPase is important for GDP‐mannose biosynthesis, a nucleotide sugar necessary for protein N‐glycosylation, it has been thought that GDP‐mannose deficiency is responsible for the growth defect in vtc1‐1 in the presence of NH4+. Therefore, the motivation for this work was to elucidate the growth and developmental processes that are affected in vtc1‐1 in the presence of NH4+ and to determine whether GDP‐mannose deficiency generally causes NH4+ sensitivity. Furthermore, as NH4+ may alter cytosolic pH, we investigated the responses of vtc1‐1 to pH changes in the presence and absence of NH4+. Using qRT‐PCR and staining procedures, we demonstrate that defective N‐glycosylation in vtc1‐1 contributes to cell wall, membrane and cell cycle defects, resulting in root growth inhibition in the presence of NH4+. However, by using mutants acting upstream of vtc1‐1 and contributing to GDP‐mannose biosynthesis, we show that GDP‐mannose deficiency does not generally lead to and is not the primary cause of NH4+ sensitivity. Instead, our data suggest that GMPase responds to pH alterations in the presence of NH4+.
Development of a hydrothermal time model that accurately characterises how thermoinhibition regulates seed germination
Authors: WATT M. S. , BLOOMBERG M. , FINCH‐SAVAGE W. E.
Published: February 2011

Thermoinhibition is the decline in germinability within a seed population as soil temperatures increase above the optimum for germination. Hydrothermal time (HTT) models have been developed that describe the thermoinhibition response as a function of increases in the threshold water potential for seed germination [seed base water potential, Ψb(G)]. Although these models assume a normal distribution of Ψb(G) and a linear upward shift in Ψb(G) with increasing temperature, little research has tested these assumptions. Using germination data obtained from four unrelated plant species, we fitted HTT models that use the Weibull and normal distribution to describe Ψb(G) and compared the accuracy and bias of these two HTT models. For all four species, Ψb(G) and germination were more accurately described by the Weibull than the normal distribution HTT model. At supra‐optimal temperatures, Ψb(G) of the earliest germinating seeds showed little thermoinhibition effect so that the seeds germinated very rapidly under moist conditions. However, for the rest of the population, Ψb(G) increased progressively in response to supra‐optimal temperatures so that the slower germinating seeds were thermoinhibited. The fitted HTT models reveal aspects of seed thermoinhibition that appear to have adaptational value under variable conditions of soil temperature and moisture.
Genetic structure and diversity of Phakopsora pachyrhizi isolates from soyabean
Authors: Twizeyimana M. , Ojiambo P. S. , Haudenshield J. S. , Caetano‐Anollés G. , Pedley K. F. , Bandyopadhyay R. , Hartman G. L.
Published: February 2011

Simple sequence repeat (SSR) markers were used to classify 116 isolates of Phakopsora pachyrhizi, the cause of soyabean rust, collected from infected soyabean leaves in four agroecological zones in Nigeria. A high degree of genetic variation was observed within the sampled populations of P. pachyrhizi. Eighty‐four distinct genotypes were identified among three of the four agroecological zones. Nei’s average genetic diversity across geographical regions was 0·22. Hierarchical analysis of molecular variance showed low genetic differentiation among all populations of P. pachyrhizi. The majority (> 90%) of the genetic diversity was distributed within each soyabean field, while approximately 6% of the genetic diversity was distributed among fields within geographic regions. Low population differentiation was indicated by the low FST values among populations, suggesting a wide dispersal of identical genotypes on a regional scale. Phylogenetic analysis indicated a strictly clonal structure of the populations and five main groups were observed, with group II accounting for 30% of the entire population. Because of the asexual reproduction of P. pachyrhizi, single‐step mutations in SSR genotypes are likely to account for the genetic differences within each group.
Ditylenchus gigas n. sp. parasitizing broad bean: a new stem nematode singled out from the Ditylenchus dipsaci species complex using a polyphasic approach with molecular phylogeny
Authors: Vovlas N. , Troccoli A. , Palomares‐Rius J. E. , De Luca F. , Liébanas G. , Landa B. B. , Subbotin S. A. , Castillo P.
Published: February 2011

Morphologial, biochemical, molecular and karyological analyses of different populations and races of the stem and bulb nematode Ditylenchus dipsaci have suggested that it represents a species complex, of which only D. dipsaci sensu stricto and its morphologically larger variant, known as the giant race of the stem and bulb nematode, are plant parasites of economic importance. The present study singles out the giant race from this complex, herein described as a new species named Ditylenchus gigas n. sp., on the basis of morphological and molecular data obtained from several populations collected from broad beans in southern Italy, southern Spain and Lebanon. The new species epithet, which refers to the large body size of the nematode with respect to the normal races, must be considered to be conspecific with the D. dipsaci‘giant race’ from Fabaceae in recent literature. Morphologically, the new species is characterized by a body size 1·5–2 times longer than the ‘normal race’, stylet delicate (11·5–13·0 μm long) with knobs distinctly sloping backwards, and long post‐vulval uterine sac (81–150 μm long). Results of molecular analysis of rDNA sequences including the ITS1‐5.8S‐ITS2 region, the D2–D3 fragment of the 28S gene, the small 18S subunit, the partial mitochondrial gene for cytochrome c oxidase I (mtCOI), and hsp90 gene sequences, support the new taxonomic species status for the former D. dipsaci giant race from Vicia faba, and clearly distinguish D. gigas n. sp. from D. dipsaci sensu stricto.
Molecular characterization of a Stagonospora nodorum lipase gene LIP1
Authors: Feng J. , Hwang R. , Hwang S.‐F. , Gaudet D. , Strelkov S. E.
Published: February 2011

A triglyceride lipase gene (LIP1) was cloned from Stagonospora nodorum, the causal agent of wheat glume blotch. LIP1 encodes a 561 amino acid preproprotein with a predicted N‐terminal signal peptide. Its expression was up‐regulated during plant infection and in culture media supplemented with saturated fatty glycerides. The recombinant Lip1 protein possessed lipolytic activity against a broad range of lipid substrates. When applied to wheat leaves, recombinant Lip1 decreased the hydrophobicity of the leaf surface, probably by liquefaction of epicuticular wax. Pretreatment of wheat leaves with Lip1 decreased the rate of conidial adhesion from 69·5% to 22·7% and from 58·9% to 28·4% in two independent assays based on different protocols. LIP1 replacement strains showed decreased lipolytic activity on culture media relative to the wild‐type strain, and adhesion of the conidia to the wheat leaf surface was impaired in the gene replacement strains. In two experiments, adhesion rates were 54·3% and 41·6% in the LIP1 replacement strains, as opposed to 77·7% and 66·6%, respectively, in the wild‐type. Collectively, the data demonstrate that the secreted lipase Lip1 is important for the adhesion of S. nodorum infection to wheat leaves.
Diversity of vegetative compatibility types and mating types of Cryphonectria parasitica in Slovenia and occurrence of associated Cryphonectria hypovirus 1
Authors: Krstin L. , Novak‐Agbaba S. , Rigling D. , Ćurković‐Perica M.
Published: February 2011

Cryphonectria parasitica, the causal agent of chestnut blight, has been present in Slovenia since at least 1950. To improve understanding of its diversity, 254 isolates of the fungus from 11 Slovenian populations were sampled. Fifteen vegetative compatibility (vc) types were identified. The dominant vc type was EU‐13, comprising 40·1% of all isolates tested, followed by EU‐1 (19·7%), EU‐2 (12·2%) and EU‐12 (9%). The vc type diversity in the most diverse population sampled in Slovenia was higher than in the populations found previously in northern Italy and Croatia. Both mating types and perithecia were observed in surveyed populations. Natural hypovirulence was found in six out of seven populations tested, with frequencies ranging from 72·2% in the population sampled near the Croatian border to 11·1% in the population sampled near the Austrian border. All identified hypoviral isolates (21) belonged to the Italian subtype of Cryphonectria hypovirus 1 and were closely related to the hypoviruses found in other European countries. Despite the high vc type diversity, incidence of hypovirulence was also high, indicating widespread natural biological control of the disease.
Dichloroisonicotinic and salicylic acid, inducers of systemic acquired resistance, enhance fungal elicitor responses in parsley cells
Authors: Kauss Heinrich , Theisinger‐Hinkel Elke , Mindermann Roswitha , Conrath Uwe
Published: February 2011

Certain plant species that were previously infected by pathogenic organisms subsequently develop a systemic resistance to further infection. This systemic acquired resistance can also be achieved by treatment with 2,6‐dichloroisonicotinic acid. Although this chemical does not directly induce coumarin secretion in suspension‐cultured cells of parsley (Petroselinum crispum), preincubation of the cultures with the compound greatly increases the subsequent induction of coumarin derivatives by a fungal elicitor, especially at low elicitor concentrations and in cell batches exhibiting a low response due to unknown variations in growth conditions. The effect appears to result from an increase in the sensitivity of the cells towards the elicitor, which causes enhanced transcription of genes coding for enzymes involved in coumarin synthesis. The enhanced transcriptional and translational activity is examplified by two specific mRNAs and the activity of phenylalanine ammonia lyase and S‐adenosyl‐l‐methionine:xantho‐toxol O‐methyl transferase. Salicylic acid, which has been implicated as an endogenous signal substance in systemic acquired resistance, causes similar but less pronounced effects. The results suggest that both acids may act by inducing increased synthesis of unknown components of the signal perception or transmission pathway which are rate‐limiting in untreated cells.
Endosperm differentiation in barley wild‐type and sex mutants
Authors: Bosnes Marie , Weideman Fredrik , Olsen Odd‐Arne
Published: February 2011

The cereal endosperm is a storage organ consisting of the central starchy endosperm surrounded by the aleurone layer. In barley, endosperm development is subdivisible into four main stages, i.e. the syncytial (I), the cellularization (II), the differentiation (III) and the maturation stage (IV). During stage I, a multinucleate syncytium is formed, which in stage II develops into the undifferentiated cellular endosperm. During stage III the cells of the endosperm differentiate into two types of aleurone cells (peripheral and modified) and three different starchy endosperm cell types (irregular, prismatic and subaleurone).

To elucidate the ontogenetic relationship between the endosperm tissues, the phenotypes of sex (shrunken endosperm mutants expressing xenia) mutant endosperms were studied. These mutants can be classified into two groups, i.e. those in which development is arrested at one of the four wild‐type stages described above, and those with abnormal development with new organizational patterns in the endosperm or with novel cell types. Based on these studies, it is suggested that the two endosperm halves represent cell lines derived from the two daughter nuclei of the primary endosperm nucleus, and that the prismatic starchy endosperm cells arise from a peripheral endosperm meristematic activity during stage III. Finally, a model for the main molecular events underlying the morphogenetic processes is discussed.
A protein from maize labeled with azido‐IAA has novel β‐glucosidase activity
Authors: Campos Narciso , Bako Laszlo , Feldwisch Joachim , Schell Jeff , Palme Klaus
Published: February 2011

A biologically active and photolabile auxin analog, 5‐azido‐[7‐3H]indole‐3‐acetic acid ([3H]N3IAA), was used to search for auxin‐binding proteins in cytosolic extracts from maize coleoptiles (Zea mays L.) and identified a protein with a molecular mass of 60 kDa (p60). Binding of [3H]N3IAA is highly specific as demonstrated by competition analysis with functionally relevant auxin analogs. p60 is found in coleoptiles and roots of etiolated maize seedlings and was detected in cytosolic as well as in microsomal fractions. The protein binds to 1‐naphthylacetic acid (1‐NAA) sepharose and is eluted with auxins. A purification scheme resulting in homogenous p60 protein was devised and it was shown that p60 has β‐d‐glucoside glucohydrolase activity (E.C.3.2.1.21). The hydrolytic activity of p60 for the synthetic substrate p‐nitro‐phenyl‐β‐d‐glucopyranoside is diminished by 1‐NAA. p60 shows high substrate specificity since it hydrolyzes indoxyl‐O‐glucoside, but not β‐(1,4)‐cellobiose, IAA‐inositol or IAA‐amino acid conjugates. The present data suggest that p60 might be involved in the hydrolysis of auxin conjugates.
A Brassica napus transcript encoding a protein related to the Künitz protease inhibitor family accumulates upon water stress in leaves, not in seeds
Authors: Downing Willa Lee , Mauxion Fabienne , Fauvarque Marie‐Odile , Reviron Marie‐Pierre , De Vienne Dominique , Vartanian Nicole , Giraudat Jérôme
Published: February 2011

A cDNA clone encoding a Brassica napus drought‐induced 22 kDa (BnD22) protein has been isolated and characterized. The BnD22 transcript accumulated in response to drought reversibly, and to other conditions of leaf water deficit such as rapid water stress or salt acclimation, but not to cold acclimation or heat shock. Exogenously applied abscisic acid induced both changes in leaf morphology similar to the drought‐adaptive response and a pronounced accumulation of the BnD22 mRNA. In control and drought‐adapted plants, the BnD22 transcript was expressed in an organ‐specific manner the mRNA level was highest in leaves, low in hypocotyls and undetectable in roots. Sequence analysis indicates that the BnD22 protein is related to the Künitz family of protease inhibitors. In contrast to most members of this family, and also to most polypeptides expressed in vegetative tissues upon drought, the BnD22 mRNA was absent in seeds, before or during the seed desiccation phase. The BnD22 gene represents a new class of genes which are strictly induced in vegetative tissues upon environmental stress, and its pattern of expression shows that the responses to water deficit differ, at least partially, in seeds and in leaves.
PCR‐aided genomic sequencing of 5'subterminal sequences of the maize transposable element Activator (Ac) in transgenic tobacco plants
Authors: Ott Thomas , Nelsen‐Salz Birgit , Döring Hans‐Peter
Published: February 2011

The maize transposable element Activator(Ac) carries subterminal CpG‐rich sequences which are essential for the transposition of the element. It has previously been shown that the methylation of certain sequences contained in this region can alter their ability to interact with the Ac‐encoded protein. The novel hypothesis that the methylation of subterminal Ac sequences is required for transposition was tested. Approximately 150 bp of the 5′ subterminal region of the Ac element was examined for the presence of 5‐methylcytosines by the ligation‐mediated polymerase chain reaction (LMPCR)‐aided genomic sequencing method. The methylation status of 22 and 39 cytosines on either strand of the DNA were analysed in each of five different transgenic tobacco cultures carrying transposable Ac sequences. Ten micrograms of tobacco DNA were used for each base‐specific cleavage reaction before amplification by LMPCR. All but one of the cytosines were unmethylated. Only a minor fraction of the Ac molecules was methylated at one cytosine residue. It is concluded that DNA methylation at the tested Ac sequences is not required for the transposability of Ac or Ds elements in tobacco cells.
Characterization of a pollen‐specific cDNA from sunflower encoding a zinc finger protein
Authors: Baltz Rachel , Domon Claire , Pillay Datta T.N. , Steinmetz André
Published: February 2011

We have isolated, via differential hybridization screening of a floral cDNA library from sunflower, a cDNA clone that hybridizes to a 1100 nucleotide‐long mRNA found exclusively in mature pollen grains. The cDNA encodes a 219 amino acid‐long polypeptide containing two potential zinc fingers alternating with two basic domains. A similar organization is found in the erythroid‐specific transcription factor Eryf1 from chicken and its murine homolog GF‐1. The C‐terminus of the protein contains a sixfold repeat of the pentapeptide sequence (S,T,A)(E,D)TQN. These features suggest that the SF3 protein is a transcription factor required for the expression of late pollen genes. The SF3 gene is a member of a multicopy gene family. A genomic copy of the gene has been isolated and sequenced; it is split by four short, AT‐rich introns.
Theptl1gene expressed in the transmitting tissue ofAntirrhinumencodes an extensin‐like protein
Authors: Baldwin Timothy C. , Coen Enrico S. , Dickinson Hugh G.
Published: February 2011

ptl1, a gene expressed specifically in pistil transmitting tissue ofAntirrhinumflowers, encodes a protein with similarity to plant extensins. The protein is rich in proline (28%) and serine (9%) and contains several proline‐rich repetitive amino acid motifs found in other extensin‐like proteins. The presence of three consensus N‐glycosylation sites indicates that it is probably glycosylated. RNA blots show that theptl1transcript is abundant in mature pistillar tissue but absent from immature flower buds and all other plant organs tested.In‐situlocalization of mRNA demonstrates thatptl1expression is confined to the transmitting tissue of the style and stigma. The presence of a putative signal peptide at the N‐terminus of the protein, taken together with the expression pattern, indicates that theptl1product may be secreted into the extracellular matrix of the transmitting tissue. The possible contributions of theptl1product to the physical properties of the transmitting tissue are considered in the light of current views on extensin structure and function.
The Arabidopsis HSP18.2 promoter/GUS gene fusion in transgenic Arabidopsis plants: a powerful tool for the isolation of regulatory mutants of the heat‐shock response
Authors: Takahashi Taku , Naito Satoshi , Komeda Yoshibumi
Published: February 2011

A detailed study of the expression of the promoter of the HSP18.2 gene from Arabidopsis fused to the bacterial gene for β‐glucuronidase (GUS) in transgenic Arabidopsis plants is described. High levels of GUS activity were induced in all organs of transformants except for seeds during heat shock. The optimum temperature for expression of GUS in Arabidopsis was 35°C regardless of the plant growth temperature. Heat shock of 40°C did not induce any detectable levels of GUS activity. Pre‐incubation at 35°C was found to have a protective effect on the induction of GUS activity at 40°C. GUS activity was also increased in response to a gradual increase in temperature. Histochemical analysis revealed that basal levels of GUS activity were induced in the vascular tissue of leaves and sepals, as well as at the tips of carpels, at the normal growth temperature. Heat treatment of a limited part of the plant tissue did not appear to cause systemic induction of GUS activity. To extend the analysis of the plant heat‐shock response, we attempted to screen mutations in genes involved in the regulation of the induction of heat‐shock protein (HSP) genes, using the GUS gene as a selection marker in transgenic Arabidopsis plants, and the results of this analysis are described.
Transgenic tobacco plants expressing rgp1, a gene encoding a ras‐related GTP‐binding protein from rice, show distinct morphological characteristics1
Authors: Kamada I. , Yamauchi S. , Youssefian S. , Sano H.
Published: February 2011

The rgp1 gene, originally Isolated from rice seedlings, encodes a small GTP‐binding protein which is related to the product of the human proto‐oncogene, ras‐p21. To determine the physiological role of the rgp1 protein, rgp1‐p25, the coding region of rgp1 was introduced into tobacco plants in both sense and antisense orientations. Transformants, which were found to contain the rgp1 gene at up to three loci, showed distinct phenotypic changes. The most notable was a reduction in apical dominance with increased tillering, together with dwarfism or abnormal flower development or both. These effects were similarly observed in both sense and antisense transformants. Northern hybridization analysis showed that rgp1 was expressed only in phenotypically abnormal transformants and not in the apparently normal phenotypes. Furthermore, the R1 progenies from most transformants co‐segregated into a 3:1 ratio for both kanamycin resistance and tillering. The expression of tgp1, a presumed tobacco homologue of rgp1, was markedly reduced in transformants expressing the antisense rgp1, whereas it was apparently unaffected in transformants with sense rgp1. These observations suggest that the phenotypic changes in antisense transformants may be mediated by an effect on native tgp1 mRNA, whereas in sense transformants the changes may be induced by over‐production of rgp1‐p25. The possibility that the increased tillering may be related to abnormal phytohormone metabolism or response pathways, and that rgp1‐p25 may mediate the transmission of signals in these pathways is discussed.
In‐situ localization of cyanogenic β‐glucosidase (linamarase) gene expression in leaves of cassava (Manihot esculenta Cranz) using non‐isotopic riboprobes
Authors: Hughes A. Pancoro and M.A.
Published: February 2011

The release of hydrogen cyanide (cyanogenesis) from damaged plant tissue depends upon the sequential action of a β‐glucosidase and an α‐hydroxynitrilase on cyanoglucosides. The non‐isotopic digoxigenin labelling system was used to visualize the presence of cyanogenic β‐glucosidase (linamarase) mRNA in cells of young leaves of Manihot esculenta Cranz (cassava). Strong hybridization to antisense riboprobes produced from the cDNA clone pCAS5, indicates localization of linamarase gene expression in laticifers (latex vessels). This is supported by the demonstration of linamarase mRNA in exuded latex. In contrast, in‐situ localization of the control gene pGLF4, showed expression in all leaf mesophyll cells. High levels of linamarase activity were demonstrated in the latex of leaf petioles and this activity was shown to be dependent on the presence of attached leaflets. Assays of α‐hydroxynitrilase activity in exuded latex and whole leaves shows that, unlike linamarase, this enzyme is present at very low levels in latex and must be located elsewhere in the leaf.
The culture response of Arabidopsis thaliana protoplasts is determined by the growth conditions of donor plants
Authors: Masson Jean , Paszkowski Jerzy
Published: February 2011

Procedures previously established for plant regeneration from mesophyll protoplasts of Arabidopsis thaliana have been optimized. The protoplast plating efficiency (number of microcalli per number of plated protoplasts) is strongly dependent on the growth conditions of the donor plant, especially medium composition and illumination conditions. The yield of microcalli is markedly influenced by the nitrogen source in the protoplast culture medium. The developed procedure gives reproducible plating efficiencies of 7–10%, i.e. 15–20 times higher than previously published (0.5%) for A. thaliana race C24.
Rapid analysis of plant gene expression by a novel reverse transcriptase‐PCR method
Authors: Simpson Craig G. , Sinibaldi Ralph , Brown John W.S.
Published: February 2011

A recently described reverse transcriptase‐polymerase chain reaction (RT‐PCR) where one oligonucleotide primer is end‐labelled has been applied to the analysis of expression of UsnRNA genes and a U2B″ protein coding gene from potato. This rapid, sensitive and accurate method of expression analysis can be applied to the study of the expression of any plant gene for which the sequence is known, in either wild‐type plants, transgenics or transfected protoplasts.
The phosphomimetic mutation of an evolutionarily conserved serine residue affects the signaling properties of Rho of plants (ROPs)
Authors: Fodor‐Dunai Csilla , Fricke Inka , Potocký Martin , Dorjgotov Dulguun , Domoki Mónika , Jurca Manuela E. , Ötvös Krisztina , Žárský Viktor , Berken Antje , Fehér Attila
Published: February 2011

Plant ROP (Rho of plants) proteins form a unique subgroup within the family of Rho‐type small G‐proteins of eukaryotes. In this paper we demonstrate that the phosphomimetic mutation of a serine residue conserved in all Rho proteins affects the signaling properties of plant ROPs. We found that the S74E mutation in Medicago ROP6 and Arabidopsis ROP4 prevented the binding of these proteins to their plant‐specific upstream activator the plant‐specific ROP nucleotide exchanger (PRONE)‐domain‐containing RopGEF (guanine nucleotide exchange factor) protein and abolished the PRONE‐mediated nucleotide exchange reaction in vitro. Structural modeling supported the hypothesis that potential phosphorylation of the S74 residue interferes with the binding of the PRONE‐domain to the adjacent plant‐specific R76 residue which plays an important role in functional ROP–PRONE interaction. Moreover, we show that while the binding of constitutively active MsROP6 to the effector protein RIC (ROP‐interactive CRIB‐motif‐containing protein) was not affected by the S74E mutation, the capability of this mutated protein to bind and activate the RRK1 kinase in vitro was reduced. These observations are in agreement with the morphology of tobacco pollen tubes expressing mutant forms of yellow fluorescent protein (YFP):MsROP6. The S74E mutation in MsROP6 had no influence on pollen tube morphology and attenuated the phenotype of a constitutively active form of MsROP6. The presented Medicago and Arabidopsis data support the notion that the phosphorylation of the serine residue in ROPs corresponding to S74 in Medicago ROP6 could be a general principle for regulating ROP activation and signaling in plants.
Analysis of short‐term changes in the Arabidopsis thaliana glycerolipidome in response to temperature and light
Authors: Burgos Asdrubal , Szymanski Jedrzej , Seiwert Bettina , Degenkolbe Thomas , Hannah Matthew A. , Giavalisco Patrick , Willmitzer Lothar
Published: February 2011

Although the influence of temperature, particularly cold, on lipid metabolism is well established, previous studies have focused on long‐term responses and have largely ignored the influence of other interacting environmental factors. Here, we present a time‐resolved analysis of the early responses of the glycerolipidome of Arabidopsis thaliana plants exposed to various temperatures (4, 21 and 32°C) and light intensities (darkness, 75, 150 and 400 μmol m−2 s−1), including selected combinations. Using a UPLC/MS‐based lipidomic platform, we reproducibly measured most glycerolipid species reported for Arabidopsis leaves, including the classes phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI) phosphatidylglycerol (PG), monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG) and sulfoquinovosyldiacylglycerol (SQDG). In addition to known lipids, we have identified previously unobserved compounds, such as 36‐C PGs and eukaryotic phospholipids containing 16:3 acyl chains. Occurrence of these lipid species implies the action of new biochemical mechanisms. Exposition of Arabidopsis plants to various light and temperature regimes results in two major effects. The first is the dependence of the saturation level of PC and MGDG pools on light intensity, likely arising from light regulation of de novo fatty acid synthesis. The second concerns an immediate decrease in unsaturated species of PG at high‐temperature conditions (32°C), which could mark the first stages of adaptation to heat‐stress conditions. Observed changes are discussed in the context of current knowledge, and new hypotheses have been formulated concerning the early stages of the plant response to changing light and temperature conditions.
The Arabidopsis trithorax‐like factor ATX1 functions in dehydration stress responses via ABA‐dependent and ABA‐independent pathways
Authors: Ding Yong , Avramova Zoya , Fromm Michael
Published: February 2011

Emerging evidence suggests that the molecular mechanisms driving the responses of plants to environmental stresses are associated with specific chromatin modifications. Here, we demonstrate that the Arabidopsis trithorax‐like factor ATX1, which trimethylates histone H3 at lysine 4 (H3K4me3), is involved in dehydration stress signaling in both abscisic acid (ABA)‐dependent and ABA‐independent pathways. The loss of function of ATX1 results in decreased germination rates, larger stomatal apertures, more rapid transpiration and decreased tolerance to dehydration stress in atx1 plants. This deficiency is caused in part by reduced ABA biosynthesis in atx1 plants resulting from decreased transcript levels from NCED3, which encodes a key enzyme controlling ABA production. Dehydration stress increased ATX1 binding to NCED3, and ATX1 was required for the increased levels of NCED3 transcripts and nucleosomal H3K4me3 that occurred during dehydration stress. Mechanistically, ATX1 affected the quantity of RNA polymerase II bound to NCED3. By upregulating NCED3 transcription and ABA production, ATX1 influenced ABA‐regulated pathways and genes. ATX1 also affected the expression of ABA‐independent genes, implicating ATX1 in diverse dehydration stress‐response mechanisms in Arabidopsis.
Alternative targeting of Arabidopsis plastidic glucose‐6‐phosphate dehydrogenase G6PD1 involves cysteine‐dependent interaction with G6PD4 in the cytosol
Authors: Meyer Tanja , Hölscher Christian , Schwöppe Christian , von Schaewen Antje
Published: February 2011

Arabidopsis peroxisomes contain an incomplete oxidative pentose‐phosphate pathway (OPPP), consisting of 6‐phosphogluconolactonase and 6‐phosphogluconate dehydrogenase isoforms with peroxisomal targeting signals (PTS). To start the pathway, glucose‐6‐phosphate dehydrogenase (G6PD) is required; however, G6PD isoforms with obvious C‐terminal PTS1 or N‐terminal PTS2 motifs are lacking. We used fluorescent reporter fusions to explore possibly hidden peroxisomal targeting information. Among the six Arabidopsis G6PD isoforms only plastid‐predicted G6PD1 with free C‐terminal end localized to peroxisomes. Detailed analyses identified SKY as an internal PTS1‐like signal; however, in a medial G6PD1 reporter fusion with free N‐ and C‐terminal ends this cryptic information was overruled by the transit peptide. Yeast two‐hybrid analyses revealed selective protein–protein interactions of G6PD1 with catalytically inactive G6PD4, and of both G6PD isoforms with plastid‐destined thioredoxin m2 (Trxm2). Serine replacement of redox‐sensitive cysteines conserved in G6PD4 abolished the G6PD4–G6PD1 interaction, albeit analogous changes in G6PD1 did not. In planta bimolecular fluorescence complementation (BiFC) demonstrated that the G6PD4–G6PD1 interaction results in peroxisomal import. BiFC also confirmed the interaction of Trxm2 with G6PD4 (or G6PD1) in plastids, but co‐expression analyses revealed Trxm2‐mediated retention of medial G6PD4 (but not G6PD1) reporter fusions in the cytosol that was stabilized by CxxC113S exchange in Trxm2. Based on preliminary findings with plastid‐predicted rice G6PD isoforms, we dismiss Arabidopsis G6PD4 as non‐functional. G6PD4 orthologs (new P0 class) apparently evolved to become cytosolic redox switches that confer thioredoxin‐relayed alternative targeting to peroxisomes.
Cell‐specific chemotyping and multivariate imaging by combined FT‐IR microspectroscopy and orthogonal projections to latent structures (OPLS) analysis reveals the chemical landscape of secondary xylem
Authors: Gorzsás András , Stenlund Hans , Persson Per , Trygg Johan , Sundberg Björn
Published: February 2011

Fourier‐transform infrared (FT‐IR) spectroscopy combined with microscopy enables chemical information to be acquired from native plant cell walls with high spatial resolution. Combined with a 64 × 64 focal plane array (FPA) detector, 4096 spectra can be simultaneously obtained from a 0.3 × 0.3 mm image; each spectrum represents a compositional and structural ‘fingerprint’ of all cell wall components. For optimal use and analysis of such a large amount of information, multivariate approaches are preferred. Here, FT‐IR microspectroscopy with FPA detection is combined with orthogonal projections to latent structures discriminant analysis (OPLS‐DA). This allows for: (i) the extraction of spectra from single cell types, (ii) identification and characterization of different chemotypes using the full spectral information, and (iii) further visualization of the pattern of identified chemotypes by multivariate imaging. As proof of concept, the chemotypes of Populus tremula xylem cell types are described. The approach revealed unknown features about chemical plasticity and patterns of lignin composition in wood fibers that would have remained hidden in the dataset with traditional data analysis. The applicability of the method to Arabidopsis xylem and its usefulness in mutant chemotyping is also demonstrated. The methodological approach is not limited to xylem tissues but can be applied to any plant organ/tissue also using other techniques such as Raman and UV microspectroscopy.