bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphatidylinositol 4,5‐bisphosphate is important for stomatal opening
Authors: Lee Yuree , Kim Yong‐Woo , Jeon Byeon Wook , Park Ki‐Youb , Suh Su Jeoung , Seo Jiyoung , Kwak June M. , Martinoia Enrico , Hwang Inhwan , Lee Youngsook 
Published: September 2007

SummaryPreviously, we demonstrated that a protein that binds phosphatidylinositol 4,5‐bisphosphate [PtdIns(4,5)P2] inhibits both light‐induced stomatal opening and ABA‐induced stomatal closing. The latter effect is due to a reduction in free PtdIns(4,5)P2, decreasing production of inositol 1,4,5‐trisphosphate and phosphatidic acid by phospholipases C and D. However, it is less clear how PtdIns(4,5)P2 modulates stomatal opening. We found that in response to white light irradiation, the PtdIns(4,5)P2‐binding domain GFP:PLCδ1PH translocated from the cytosol into the plasma membrane. This suggests that the level of PtdIns(4,5)P2 increases at the plasma membrane upon illumination. Exogenously administered PtdIns(4,5)P2 substituted for light stimuli, inducing stomatal opening and swelling of guard cell protoplasts. To identify PtdIns(4,5)P2 targets we performed patch‐clamp experiments, and found that anion channel activity was inhibited by PtdIns(4,5)P2. Genetic analyses using an Arabidopsis PIP5K4 mutant further supported the role of PtdIns(4,5)P2 in stomatal opening. The reduced stomatal opening movements exhibited by a mutant of Arabidopsis PIP5K4 (At3g56960) was countered by exogenous application of PtdIns(4,5)P2. The phenotype of reduced stomatal opening in the pip5k4 mutant was recovered in lines complemented with the full‐length PIP5K4. Together, these data suggest that PIP5K4 produces PtdIns(4,5)P2 in irradiated guard cells, inhibiting anion channels to allow full stomatal opening.
A novel serine/proline‐rich domain in combination with a transmembrane domain is required for the insertion of AtTic40 into the inner envelope membrane of chloroplasts
Authors: Tripp Joanna , Inoue Kentaro , Keegstra Kenneth , Froehlich John E. 
Published: September 2007

SummaryAtTic40 is part of the chloroplastic protein import apparatus that is anchored in the inner envelope membrane by a single N‐terminal transmembrane domain, and has a topology in which the bulk of the C‐terminal domain is oriented toward the stroma. The targeting of AtTic40 to the inner envelope membrane involves two steps. Using an in vitro import assay, we showed that the sorting of AtTic40 requires a bipartite transit peptide, which was first cleaved by the stromal processing peptidase (SPP), thus generating a soluble AtTic40 stromal intermediate (iAtTic40). iAtTic40 was further processed by a second unknown peptidase, which generates its mature form (mAtTic40). Using deletion mutants, we identified a sequence motif N‐terminal of the transmembrane domain that was essential for reinsertion of iAtTic40 into the inner envelope membrane. We have designated this region a serine/proline‐rich (S/P‐rich) domain and present a model describing its role in the targeting of AtTic40 to the inner envelope membrane.
Silencing of DELLA induces facultative parthenocarpy in tomato fruits
Authors: Martí Cristina , Orzáez Diego , Ellul Philippe , Moreno Vicente , Carbonell Juan , Granell Antonio 
Published: September 2007

SummaryDELLA proteins are plant nuclear factors that restrain growth and proliferation in response to hormonal signals. The effects of the manipulation of the DELLA pathway in the making of a berry‐like fruit were investigated. The expression of the Arabidopsis thaliana gain‐of‐function DELLA allele Atgai del in tomato (Solanum lycopersicum L.) produced partially sterile dwarf plants and compacted influorescences, as expected for a constitutively activated growth repressor. In contrast, antisense silencing of the single endogenous tomato DELLA gene homologue (SlDELLA) produced slender‐like plants with elongated flower trusses. Interestingly, the depletion of SlDELLA in tomato was sufficient to overcome the growth arrest normally imposed on the ovary at anthesis, resulting in parthenocarpic fruits in the absence of pollination. Antisense SlDELLA‐engineered fruits were smaller in size and elongated in shape compared with wild type. Cell number estimations showed that fruit set, resulting from reduced SlDELLA expression, arose from activated cell elongation at the longitudinal and lateral axes of the fruit pericarp, bypassing phase‐II (post‐pollination) cell divisions. Parthenocarpy caused by SlDELLA depletion is facultative, as hand pollination restored wild‐type fruit phenotype. This indicates that fertilization‐associated SlDELLA‐independent signals are operational in ovary–fruit transitions. SlDELLA was also found to restrain growth in other reproductive structures, affecting style elongation, stylar hair primordial growth and stigma development.
Overexpression of a chromatin architecture‐controlling AT‐hook protein extends leaf longevity and increases the post‐harvest storage life of plants
Authors: Lim Pyung Ok , Kim Yumi , Breeze Emily , Koo Ja Choon , Woo Hye Ryun , Ryu Jong Sang , Park Don Ha , Beynon Jim , Tabrett Alex , Buchanan‐Wollaston Vicky , Nam Hong Gil 
Published: September 2007

SummaryLeaf senescence is the final stage of leaf development and is finely regulated via a complex genetic regulatory network incorporating both developmental and environmental factors. In an effort to identify negative regulators of leaf senescence, we screened activation‐tagged Arabidopsis lines for mutants that exhibit a delayed leaf senescence phenotype. One of the mutants (ore7‐1D) showed a highly significant delay of leaf senescence in the heterozygous state, leading to at least a twofold increase in leaf longevity. The activated gene (ORE7/ESC) encoded a protein with an AT‐hook DNA‐binding motif; such proteins are known to co‐regulate transcription of genes through modification of chromatin architecture. We showed that ORE7/ESC, in addition to binding to a plant AT‐rich DNA fragment, could also modify the chromatin architecture, as illustrated by an altered distribution of a histone–GFP fusion protein in the nucleus of the mutant. Globally altered gene expression, shown by microarray analysis, also indicated that activation of ORE7/ESC results in a younger condition in the mutant leaves. We propose that ectopically expressed ORE7/ESC is negatively regulating leaf senescence and suggest that the resulting chromatin alteration may have a role in controlling leaf longevity. Interestingly, activation of ORE7/ESC also led to a highly extended post‐harvest storage life.
Duplicated P5CS genes of Arabidopsis play distinct roles in stress regulation and developmental control of proline biosynthesis
Authors: Székely Gyöngyi , Ábrahám Edit , Cséplő Ágnes , Rigó Gábor , Zsigmond Laura , Csiszár Jolán , Ayaydin Ferhan , Strizhov Nicolai , Jásik Jan , Schmelzer Elmon , Koncz Csaba , Szabados László 
Published: September 2007

SummaryΔ‐1‐pyrroline‐5‐carboxylate synthetase enzymes, which catalyse the rate‐limiting step of proline biosynthesis, are encoded by two closely related P5CS genes in Arabidopsis. Transcription of the P5CS genes is differentially regulated by drought, salinity and abscisic acid, suggesting that these genes play specific roles in the control of proline biosynthesis. Here we describe the genetic characterization of p5cs insertion mutants, which indicates that P5CS1 is required for proline accumulation under osmotic stress. Knockout mutations of P5CS1 result in the reduction of stress‐induced proline synthesis, hypersensitivity to salt stress, and accumulation of reactive oxygen species. By contrast, p5cs2 mutations cause embryo abortion during late stages of seed development. The desiccation sensitivity of p5cs2 embryos does not reflect differential control of transcription, as both P5CS mRNAs are detectable throughout embryonic development. Cellular localization studies with P5CS–GFP gene fusions indicate that P5CS1 is sequestered into subcellular bodies in embryonic cells, where P5CS2 is dominantly cytoplasmic. Although proline feeding rescues the viability of mutant embryos, p5cs2 seedlings undergo aberrant development and fail to produce fertile plants even when grown on proline. In seedlings, specific expression of P5CS2–GFP is seen in leaf primordia where P5CS1–GFP levels are very low, and P5CS2–GFP also shows a distinct cell‐type‐specific and subcellular localization pattern compared to P5CS1–GFP in root tips, leaves and flower organs. These data demonstrate that the Arabidopsis P5CS enzymes perform non‐redundant functions, and that P5CS1 is insufficient for compensation of developmental defects caused by inactivation of P5CS2.
Antagonistic selection between adult thorax and wing size in field released Drosophila melanogaster independent of thermal conditions
Authors: HOFFMANN A. A. , RATNA E. , SGRÒ C. M. , BARTON M. , BLACKET M. , HALLAS R. , DE GARIS S. , WEEKS A. R. 
Published: September 2007

AbstractAttempts to explain size variation in Drosophila and other small insects often focus on the larval stage and association between development time and size, but patterns are also influenced by direct selection on size‐related traits in the adults. Here we use multiple field releases of Drosophila melanogaster to test the association between size and one component of field fitness, the ability of Drosophila to locate resources for feeding and breeding. We find antagonistic selection between wing length and thorax length in both males and females, such that capture at baits is higher for flies with relatively larger thorax lengths and smaller wings. However flies with large wings relative to thoraces disperse further as reflected in the longer distances moved to baits. These patterns did not depend strongly on weather conditions, suggesting that selection on adult size is at least partly independent of temperature. Antagonistic selection between size traits can generate changes in size along gradients if the distribution of resources in the environment varies and selects for different dispersal patterns, particularly as dispersal is relatively higher under warmer conditions.
Out‐of‐Africa origin and dispersal‐mediated diversification of the butterfly genus Junonia (Nymphalidae: Nymphalinae)
Authors: KODANDARAMAIAH U. , WAHLBERG N. 
Published: September 2007

AbstractThe relative importance of dispersal and vicariance in the diversification of taxa has been much debated. Within butterflies, a few studies published so far have demonstrated vicariant patterns at the global level. We studied the historical biogeography of the genus Junonia (Nymphalidae: Nymphalinae) at the intercontinental level based on a molecular phylogeny. The genus is distributed over all major biogeographical regions of the world except the Palaearctic. We found dispersal to be the dominant process in the diversification of the genus. The genus originated and started diversifying in Africa about 20 Ma and soon after dispersed into Asia possibly through the Arabian Peninsula. From Asia, there were dispersals into Africa and Australasia, all around 5 Ma. The origin of the New World species is ambiguous; the ancestral may have dispersed from Asia via the Beringian Strait or from Africa over the Atlantic, about 3 Ma. We found no evidence for vicariance at the intercontinental scale. We argue that dispersal is as important as vicariance, if not more, in the global diversification of butterflies.
Ecological selection against hybrids in natural populations of sympatric threespine sticklebacks
Authors: GOW J. L. , PEICHEL C. L. , TAYLOR E. B. 
Published: September 2007

AbstractExperimental work has provided evidence for extrinsic post‐zygotic isolation, a phenomenon unique to ecological speciation. The role that ecological components to reduced hybrid fitness play in promoting speciation and maintaining species integrity in the wild, however, is not as well understood. We addressed this problem by testing for selection against naturally occurring hybrids in two sympatric species pairs of benthic and limnetic threespine sticklebacks (Gasterosteus aculeatus). If post‐zygotic isolation is a significant reproductive barrier, the relative frequency of hybrids within a population should decline significantly across the life‐cycle. Such a trend in a natural population would give independent support to experimental evidence for extrinsic, rather than intrinsic, post‐zygotic isolation in this system. Indeed, tracing mean individual hybridity (genetic intermediateness) across three life‐history stages spanning four generations revealed just such a decline. This provides compelling evidence that extrinsic selection plays an important role in maintaining species divergence and supports a role for ecological speciation in sticklebacks.
The dynamics of sexual conflict over mating rate with endosymbiont infection that affects reproductive phenotypes
Authors: HAYASHI T. I. , MARSHALL J. L. , GAVRILETS S. 
Published: September 2007

AbstractMaternally inherited endosymbionts have been implicated as significant drivers of sexual conflict within their hosts, typically through sex‐ratio manipulation. Empirical studies show that some of these endosymbionts have the potential to influence sexual conflict not by sex‐ratio distortion, but by altering reproductive traits within their hosts. Research has already shown that reproductive traits involved in mating/fertilization process are integral ‘players’ in sexual conflict, thus suggesting the novel hypothesis that endosymbiont‐induced changes in reproductive phenotypes can impact the dynamics of sexual conflict. Here, we use a standard quantitative genetic approach to model the effects of endosymbiont‐induced changes in a female reproductive trait on the dynamics of sexual conflict over mating/fertilization rate. Our model shows that an endosymbiont‐induced alteration of a host female reproductive trait that affects mating rate can maintain the endosymbiont infection within the host population, and does so in the absence of sex‐ratio distortion and cytoplasmic incompatibility.
Growth and Anti‐Oxidative Systems Changes in Elymus dahuricus is Affected by Neotyphodium Endophyte Under Contrasting Water Availability
Authors: Zhang Y. P. , Nan Z. B. 
Published: September 2007

AbstractAlthough the relationship between fungal endophyte and agronomic grass (Lolium perenne and Festuca arundinacea) in drought tolerance are well documented, the mechanisms responsible for wild grass are not well understood. In this study, we determined the biomass production and growth parameters endophyte infected (E+) and endophyte uninfected (E−) Elymus dahuricus plants under high water (HW) and low water (LW) treatment for 8 weeks in a controlled‐environment condition experiment. We also determined the changes in the activities of the anti‐oxidative enzymes superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and content of H2O2, as well as levels of proline and chlorophyll a + b were examined in the leaves of E+ and E− plants. Under low water treatment, E+ plants produced more biomass and had higher values in plant height and tiller numbers, but no influence by the fungus were observed in high water treatment. Anti‐oxidative enzyme (include SOD, POD, CAT and APX) activities and contents of proline and chlorophyll a + b increased and H2O2 concentration declined in the E+ plants compared with E− plants under low water treatment. Therefore, endophyte infection was a benefit to growth and anti‐oxidative affection E. dahuricus under low water treatment.
Effect of Prohexadione Calcium on Growth Components and Endogenous Gibberellins Contents of Rice (Oryza sativa L.)
Authors: Kim H.Y. , Lee I.J. , Hamayun M. , Kim J.T. , Won J.G. , Hwang I.C. , Kim K.U. 
Published: September 2007

AbstractProhexadione calcium (Pro‐Ca) is a novel plant growth regulator that inhibits the late stages of gibberellins (GAs) biosynthesis in plants, thus reducing the vegetative growth of the plant. Pro‐Ca was applied to field‐grown rice cultivar Ilpumbyeo to evaluate its effect on growth and yield components and endogenous GAs, when applied at different rates and timings. This study illustrated that Pro‐Ca application decreased the internode length, stem length, panicle length, shoots fresh weight and stem lodging index, while stem breaking force was increased in all treatments. The effect of Pro‐Ca was more pronounced in 20 ppm concentration than 10 ppm. The number of panicles m−2, ripened grain ratio and 1000 grain weight and milled rice yield parameters, increased with the application of Pro‐Ca, though the number of grains per panicle decreased insignificantly. The endogenous bioactive GA1 contents significantly decreased with the application of Pro‐Ca, as the GA biosynthesis was interrupted at later stages, when GA20 conversion to GA1 was blocked, thus drastically reducing GA1 and GA8 levels, but only insignificant changes were observed for intermediates from GA12 to GA20. The levels of the endogenous GAs in rice shoots were measured by GC‐MS‐SIM using 2H2‐labelled GAs as internal standards. Present results also illustrated that early application of Pro‐Ca was more effective than its late application for effective control of different growth parameters and thus reducing lodging in rice plants.
Relationship between Carbon Isotope Discrimination and Grain Yield in Spring Wheat under Different Water Regimes and under Saline Conditions in the Ningxia Province (North‐west China)
Authors: Xu X. , Yuan H. , Li S. , Monneveux P. 
Published: September 2007

AbstractThe relationship between grain yield and carbon isotope discrimination (Δ) was analysed in wheat grown under different water regimes in the Ningxia Province (north‐west of China). When the association was significant, the relationships between grain yield, Δ and other drought tolerance related traits, such as leaf ash content (ma), chlorophyll concentration (Chl), relative water content (RWC), stomatal conductance (gS) and the ratio of internal CO2 leaf concentration to ambient CO2 concentration (Ci/Ca), were also examined. Using correlation analysis, the relationships were determined during two consecutive years in a set of 20 spring wheat cultivars (landraces, improved varieties and advanced lines) under rainfed and irrigated conditions, including saline conditions. The relationship between Δ and yield within environments highly depended on the quantity of water stored in the soil at sowing, the quantity and distribution of rainfall during the growth cycle, and the irrigation before anthesis. Δ predicted grain yield under limited irrigation (post‐anthesis water stress) but not under pre‐anthesis water stress (rainfed conditions), fully irrigated and saline conditions. Under limited irrigation, grain Δ correlated significantly to grain yield leaf ma at heading and maturity. It also significantly positively correlated to Chl, RWC, gS and Ci/Ca assessed at anthesis. A precise characterization of the timing and intensity of the abiotic constraints experienced by the crop is consequently needed before implementing the use of Δ in wheat breeding programmes.
The Effects of Bacillus pumilus, Isolated from Wheat Rhizosphere, on Resistance in Wheat Seedling Roots against the Take‐all Fungus, Gaeumannomyces graminis var. tritici
Authors: Sari E. , Etebarian H. R. , Aminian H. 
Published: September 2007

AbstractThe aim of this study was to verify that induced resistance was another mechanism through which Bacillus pumilus 7 km can suppress Gaeumannomyces graminis (Sacc.) Von Arx and Oliver var. tritici Walker (Ggt). Also, plant growth‐promotion activity of B. pumilus 7 km and its effect on disease severity of take‐all were evaluated. Soil was drenched with B. pumilus 7 km and disease severity, root and shoot fresh weights and root and shoot heights were evaluated. The activities of soluble peroxidase (SPOX), ionically cell wall‐bound peroxidase (CWPOX), β‐1,3‐glucanase, β‐1,4‐glucanase and the contents of total phenolic compounds were also determined. The results indicated that disease severity in the bacterized roots was significantly less than the pathogen control roots. Also this isolate promoted root height, root and shoot fresh weights, compared with the healthy control plants. Wheat plants treated with B. pumilus 7 km showed increased presence of SPOX, CWPOX, β‐1,3‐glucanase, β‐1,4‐glucanase and phenolic compounds in bacterized roots challenged with the pathogen. In this treatment, maximum SPOX, β‐1,3‐glucanase and β‐1,4‐glucanase activities on day 4 and CWPOX activity on day 8 were recorded. Also, maximum total phenolic concentration on day 6 was recorded. The results suggest that the inhibitory effect of B. pumilus 7 km on the take‐all may be related to its ability to enhance defense responses in the wheat roots.
The properties of reticular thalamic neuron GABAA IPSCs of absence epilepsy rats lead to enhanced network excitability
Authors: Tóth T. I. , Bessaïh T. , Leresche N. , Crunelli V. 
Published: September 2007

AbstractBoth human investigations and studies in animal models have suggested that abnormalities in GABAA receptor function have a potential role in the pathophysiology of absence seizures. Recently we showed that, prior to seizure onset, GABAA IPSCs in thalamic reticular (NRT) neurons of genetic absence epilepsy rats from Strasbourg (GAERS) had a 25% larger amplitude, a 40% faster decay and a 45% smaller paired‐pulse depression than those of nonepileptic control (NEC) rats. By means of a novel mathematical description, the properties of both GAERS and NEC GABAergic synapses can be mimicked. These model synapses were then used in an NRT network model in order to investigate their potential impact on the neuronal firing patterns. Compared to NEC, GAERS NRT neurons show an overall increase in excitability and a higher frequency and regularity of firing in response to periodic input signals. Moreover, in response to randomly distributed stimuli, the GAERS but not the NEC model produces resonance between 7 and 9 Hz, the frequency range of spike–wave discharges in GAERS. The implications of these results for the epileptogenesis of absence seizures are discussed.
Disruption of maternal behaviour by acute conspecific interaction induces selective activation of the lateral periaqueductal grey
Authors: Pavesi Elolsa , Enck Michelle Cabral , De Toledo Claudio Antonio Barbosa , Terenzi Mariana Graciela 
Published: September 2007

AbstractMaternal behaviour is sensitive to stress and opioidergic activation. The periaqueductal grey (PAG) is involved in coping strategies to stress, whereas morphine inhibition of maternal behaviour depends on the activation of the PAG. The aim of this study was to investigate whether the PAG is activated by disrupting maternal behaviour. Lactating Wistar rats were assigned to four groups: C (control); E1 (acute exposure to a male rat); E2 (daily 2‐h exposure to another lactating female and a male rat from Day 3 to 6 of lactation); and E1 + 2 (treated first as E2 and, on Day 9, as E1). Maternal behaviour was recorded on Day 9 of lactation and analysed for 1 h. The E1 group spent more time retrieving their pups, took longer to initiate nursing, had shorter nursing bouts and spent more time in non‐maternal activities compared with control. Rats submitted to E2 or E1 + 2 did not differ from the control. In another experiment, lactating rats were treated as above, except that 90 min after the end of the observation period the rats were killed and their brains were processed for immunohistochemical detection of Fos protein in the PAG. Fos increased in the lateral PAG only in the E1 group. We also observed that neurons activated by acute conspecific interaction in the PAG could be responsible for an opioid‐dependent decrease in maternal behaviour as this effect was reversed by a microinjection of naltrexone, nor‐binaltorphimine or naloxonazine into the lateral PAG. Chronic conspecific interaction alters the way this circuitry responds to acute conspecific interaction.