bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of Plant Defense Proteins in the Gut of Insect Herbivores
Authors: Chen Hui , Gonzales-Vigil Eliana , Wilkerson Curtis G. , Howe Gregg A. 
Published: February 2007

Abstract
Plant defense against insect herbivores is mediated in part by enzymes that impair digestive processes in the insect gut. Little is known about the evolutionary origins of these enzymes, their distribution in the plant kingdom, or the mechanisms by which they act in the protease-rich environment of the animal digestive tract. One example of such an enzyme is threonine (Thr) deaminase (TD), which in tomato (Solanum lycopersicum) serves a dual role in isoleucine (Ile) biosynthesis in planta and Thr degradation in the insect midgut. Here, we report that tomato uses different TD isozymes to perform these functions. Whereas the constitutively expressed TD1 has a housekeeping role in Ile biosynthesis, expression of TD2 in leaves is activated by the jasmonate signaling pathway in response to herbivore attack. Ingestion of tomato foliage by specialist (Manduca sexta) and generalist (Trichoplusia ni) insect herbivores triggered proteolytic removal of TD2's C-terminal regulatory domain, resulting in an enzyme that degrades Thr without being inhibited through feedback by Ile. This processed form (pTD2) of TD2 accumulated to high levels in the insect midgut and feces (frass). Purified pTD2 exhibited biochemical properties that are consistent with a postingestive role in defense. Shotgun proteomic analysis of frass from tomato-reared M. sexta identified pTD2 as one of the most abundant proteins in the excrement. Among the other tomato proteins identified were several jasmonate-inducible proteins that have a known or proposed role in anti-insect defense. Subtilisin-like proteases and other pathogenesis-related proteins, as well as proteins of unknown function, were also cataloged. We conclude that proteomic analysis of frass from insect herbivores provides a robust experimental approach to identify hyperstable plant proteins that serve important roles in defense.
Regulation of Arbuscular Mycorrhization by Carbon. The Symbiotic Interaction Cannot Be Improved by Increased Carbon Availability Accomplished by Root-Specifically Enhanced Invertase Activity
Authors: Schaarschmidt Sara , González Mari-Cruz , Roitsch Thomas , Strack Dieter , Sonnewald Uwe , Hause Bettina 
Published: February 2007

AbstractThe mutualistic interaction in arbuscular mycorrhiza (AM) is characterized by an exchange of mineral nutrients and carbon. The major benefit of AM, which is the supply of phosphate to the plant, and the stimulation of mycorrhization by low phosphate fertilization has been well studied. However, less is known about the regulatory function of carbon availability on AM formation. Here the effect of enhanced levels of hexoses in the root, the main form of carbohydrate used by the fungus, on AM formation was analyzed. Modulation of the root carbohydrate status was performed by expressing genes encoding a yeast (Saccharomyces cerevisiae)-derived invertase, which was directed to different subcellular locations. Using tobacco (Nicotiana tabacum) alc∷cwINV plants, the yeast invertase was induced in the whole root system or in root parts. Despite increased hexose levels in these roots, we did not detect any effect on the colonization with Glomus intraradices analyzed by assessment of fungal structures and the level of fungus-specific palmitvaccenic acid, indicative for the fungal carbon supply, or the plant phosphate content. Roots of Medicago truncatula, transformed to express genes encoding an apoplast-, cytosol-, or vacuolar-located yeast-derived invertase, had increased hexose-to-sucrose ratios compared to β-glucuronidase-transformed roots. However, transformations with the invertase genes did not affect mycorrhization. These data suggest the carbohydrate supply in AM cannot be improved by root-specifically increased hexose levels, implying that under normal conditions sufficient carbon is available in mycorrhizal roots. In contrast, tobacco rolC∷ppa plants with defective phloem loading and tobacco pyk10∷InvInh plants with decreased acid invertase activity in roots exhibited a diminished mycorrhization.
Arabidopsis Vacuolar Sorting Mutants (green fluorescent seed) Can Be Identified Efficiently by Secretion of Vacuole-Targeted Green Fluorescent Protein in Their Seeds
Authors: Fuji Kentaro , Shimada Tomoo , Takahashi Hideyuki , Tamura Kentaro , Koumoto Yasuko , Utsumi Shigeru , Nishizawa Keito , Maruyama Nobuyuki , Hara-Nishimura Ikuko 
Published: February 2007

Abstract
Two Arabidopsis thaliana genes have been shown to function in vacuolar sorting of seed storage proteins: a vacuolar sorting receptor, VSR1/ATELP1, and a retromer component, MAIGO1 (MAG1)/VPS29. Here, we show an efficient and simple method for isolating vacuolar sorting mutants of Arabidopsis. The method was based on two findings in this study. First, VSR1 functioned as a sorting receptor for β-conglycinin by recognizing the vacuolar targeting signal. Second, when green fluorescent protein (GFP) fusion with the signal (GFP-CT24) was expressed in vsr1, mag1/vps29, and wild-type seeds, both vsr1and mag1/vps29 gave strongly fluorescent seeds but the wild type did not, suggesting that a defect in vacuolar sorting provided fluorescent seeds by the secretion of GFP-CT24 out of the cells. We mutagenized transformant seeds expressing GFP-CT24. From ∼3,000,000 lines of M2 seeds, we obtained &gt;100 fluorescent seeds and designated them green fluorescent seed (gfs) mutants. We report 10 gfs mutants, all of which caused missorting of storage proteins. We mapped gfs1 to VSR1, gfs2 to KAM2/GRV2, gfs10 to the At4g35870 gene encoding a novel membrane protein, and the others to different loci. This method should provide valuable insights into the complex molecular mechanisms underlying vacuolar sorting of storage proteins.
Unique, Shared, and Redundant Roles for theArabidopsisSWI/SNF Chromatin Remodeling ATPases BRAHMA and SPLAYED
Authors: Bezhani Staver , Winter Cara , Hershman Steve , Wagner John D. , Kennedy John F. , Kwon Chang Seob , Pfluger Jennifer , Su Yanhui , Wagner Doris 
Published: February 2007

AbstractChromatin remodeling is emerging as a central mechanism for patterning and differentiation in multicellular eukaryotes. SWI/SNF chromatin remodeling ATPases are conserved in the animal and plant kingdom and regulate transcriptional programs in response to endogenous and exogenous cues. In contrast with their metazoan orthologs, null mutants in two Arabidopsis thaliana SWI/SNF ATPases, BRAHMA (BRM) and SPLAYED (SYD), are viable, facilitating investigation of their role in the organism. Previous analyses revealed that syd and brm null mutants exhibit both similar and distinct developmental defects, yet the functional relationship between the two closely related ATPases is not understood. Another central question is whether these proteins act as general or specific transcriptional regulators. Using global expression studies, double mutant analysis, and protein interaction assays, we find overlapping functions for the two SWI/SNF ATPases. This partial diversification may have allowed expansion of the SWI/SNF ATPase regulatory repertoire, while preserving essential ancestral functions. Moreover, only a small fraction of all genes depends on SYD or BRM for expression, indicating that these SWI/SNF ATPases exhibit remarkable regulatory specificity. Our studies provide a conceptual framework for understanding the role of SWI/SNF chromatin remodeling in regulation of Arabidopsis development.
A Conserved Carboxylesterase Is a SUPPRESSOR OF AVRBST-ELICITED RESISTANCE inArabidopsis
Authors: Cunnac Sébastien , Wilson Ariane , Nuwer Jamie , Kirik Angela , Baranage Gayathri , Mudgett Mary Beth 
Published: February 2007

AbstractAvrBsT is a type III effector from Xanthomonas campestris pv vesicatoria that is translocated into plant cells during infection. AvrBsT is predicted to encode a Cys protease that targets intracellular host proteins. To dissect AvrBsT function and recognition in Arabidopsis thaliana, 71 ecotypes were screened to identify lines that elicit an AvrBsT-dependent hypersensitive response (HR) after Xanthomonas campestris pv campestris (Xcc) infection. The HR was observed only in the Pi-0 ecotype infected with Xcc strain 8004 expressing AvrBsT. To create a robust pathosystem to study AvrBsT immunity in Arabidopsis, the foliar pathogen Pseudomonas syringae pv tomato (Pst) strain DC3000 was engineered to translocate AvrBsT into Arabidopsis by the Pseudomonas type III secretion (T3S) system. Pi-0 leaves infected with Pst DC3000 expressing a Pst T3S signal fused to AvrBsT-HA (AvrBsTHYB-HA) elicited HR and limited pathogen growth, confirming that the HR leads to defense. Resistance in Pi-0 is caused by a recessive mutation predicted to inactivate a carboxylesterase known to hydrolyze lysophospholipids and acylated proteins in eukaryotes. Transgenic Pi-0 plants expressing the wild-type Columbia allele are susceptible to Pst DC3000 AvrBsTHYB-HA infection. Furthermore, wild-type recombinant protein cleaves synthetic p-nitrophenyl ester substrates in vitro. These data indicate that the carboxylesterase inhibits AvrBsT-triggered phenotypes in Arabidopsis. Here, we present the cloning and characterization of the SUPPRESSOR OF AVRBST-ELICITED RESISTANCE1.
Sources of natural resistance to plant viruses: status and prospects
Authors: MAULE ANDREW J. , CARANTA CAROLE , BOULTON MARGARET I. 
Published: February 2007

SUMMARYGlobally, virus diseases are common in agricultural crops and have a major agronomic impact. They are countered through the deployment of genetic resistance against the virus, or through the use of a range of farming practices based upon the propagation of virus‐free plant material and the exclusion of the virus vectors from the growing crop. We review here the current status of our knowledge of natural virus resistance genes, and consider the future prospects for the deployment of these genes against virus infection.
Rat salivary gland ligation causes reversible secretory hypofunction
Authors: Carpenter G. H. , Osailan S. M. , Correia P. , Paterson K. P. , Proctor G. B. 
Published: February 2007

AbstractAim:  To determine the influence of inflammation on salivary secretion. Secretion by salivary glands involves interactions between nerves, blood vessels and salivary cells. The present study investigated the effects of inflammation on rat submandibular gland function following acute ductal obstruction.Methods:  Under recovery anaesthesia a metal clip was placed on the main duct of the submandibular gland. After 24 h salivary secretion was evoked by nerve and methacholine stimulation. For recovery experiments the clip was removed after 24 h and the animal left to recover for 3 days when salivary function was again assessed.Results:  By 24 h of obstruction an inflammatory infiltrate had developed within the obstructed gland and stimulated salivary flows were just 20% of the normal secretion, whilst protein secretion and ion reabsorption were also severely impaired. If ductal obstruction was removed after 24 h the salivary function returned to normal after 3 days of recovery. In vitro analysis of cells from 24‐h ligated glands revealed normal changes in intracellular calcium (the main secondary messenger involved in fluid secretion) in response to methacholine stimulation. Protein secretion from isolated cells indicated some changes in particular to methacholine‐induced protein secretion although a significant protein secretion was still seen in response to isoprenaline – the main stimulus for protein secretion.Conclusion:  This report demonstrates reversible salivary inhibition associated with an inflammatory infiltrate within the salivary gland.
Large‐scale glaciotectonic‐imbricated thrust sheets on three‐dimensional seismic data: facts or artefacts?
Authors: Rafaelsen Bjarne , Andreassen Karin , Hogstad Kai , Kuilman Luppo W. 
Published: February 2007

ABSTRACTImbricate reflections commonly occur in the glacigenic section of seismic profiles from the Bjørnøya Trough. This was the main drainage pathway for fast‐flowing ice‐streams from the former Barents Sea and Scandinavian ice sheets. Industry three‐dimensional (3D) seismic data from the southern flank of the Bjørnøya Trough are used here to investigate these imbricate reflections. Integration of vertical seismic sections with 3D plan view images and attribute maps reveal that imbricate reflections at the SW Barents Sea Margin are mega‐scale sediment blocks with a glacigenic origin. Imbricate reflections in two regions to the east of the survey appear on plan‐view as well‐developed lineations of U‐shaped crescents; however, following detailed analysis of their location, geometry and relation to sailing direction during data acquisition, we can demonstrate that these are seismic artefacts. These artefacts are related to the straight parts of east–west‐trending plough marks on the sea floor, having a dip direction that is directly related to the sailing direction of the ship during seismic acquisition. By analysing both real glacigenic imbrications and false imbrications or artefacts, we are able to demonstrate the critical distinguishing criterion.
Modulation of glucocorticoid metabolism by the growth hormone – IGF‐1 axis
Authors: Agha Amar , Monson John P. 
Published: February 2007

SummaryThe growth hormone‐insulin‐like growth factor 1 (GH‐IGF‐1) axis plays an important role in modulating the peripheral metabolism of glucocorticoids mainly through its effect on the isoenzyme 11 β‐hydroxysteroid dehydrogenase 1 (11β‐HSD1) which, in vivo, functions as a reductase catalysing the conversion of cortisone to cortisol. Several in vivo and ex vivo studies have shown that the GH‐IGF‐I system inhibits the expression and activity of 11β‐HSD1 in adipose tissues and the liver resulting in reduced local regeneration of cortisol. This interaction has clinically significant implications as it may at least partly explain the phenotypes of acromegaly and adult GH deficiency and the effects that treatment of these conditions has on body composition. In addition, by accelerating the peripheral metabolism of cortisol, GH therapy may precipitate adrenal insufficiency in susceptible hypopituitary patients, and endocrinologists should be mindful of this phenomenon when starting hypopituitary patients on GH replacement therapy.
Increased insulin‐stimulated endothelin‐1 release is a distinct vascular phenotype distinguishing Cushing's disease from metabolic syndrome
Authors: Setola Emanuela , Losa Marco , Lanzi Roberto , Lucotti Pietro , Monti Lucilla D. , Castrignanò Tristana , Galluccio Elena , Giovanelli Massimo , Piatti PierMarco 
Published: February 2007

SummaryObjective  Although much is known about the anti‐inflammatory effects of an acute corticosteroid therapy, little is known about the effects on chronic hypercortisolism on endothelial dysfunction and proinflammatory alterations in patients with Cushing's disease (CD).Patients and methods  We studied 9 patients with CD, 10 patients with metabolic syndrome and 27 normal controls. The tests consisted of an intravenous bolus of 0·1 U/kg insulin combined with a euglycaemic clamp technique with an arterialized forearm and assessment of the training parameters deep‐venous balance of forearm glucose uptake (as an index of insulin sensitivity); NOx (nitric oxide end‐products), c‐GMP (second messenger of nitric oxide) and endothelin‐1 release, as indices of endothelial function and proinflammatory systemic markers.Results  Forearm glucose uptake incremental area was significantly lower in Cushing's disease and in the metabolic syndrome than in controls, suggesting a state of severe insulin resistance. Compared to controls and to the metabolic syndrome, basal and insulin‐stimulated NOx release incremental areas were significantly reduced in Cushing's disease, while forearm c‐GMP release was similarly decreased in CD and metabolic syndrome. By contrast, endothelin‐1 incremental areas after insulin bolus were significantly higher in CD than in controls and the metabolic syndrome, in the presence of increased TNF‐alpha, IL‐6 and CRP levels. Forearm glucose uptake incremental area significantly correlated with NOx incremental area, forearm c‐GMP release incremental area, TNF‐alpha levels and ET‐1 incremental area.Conclusions  In patients with CD, supraphysiological insulin levels are not able to overcome the insulin resistance due to chronic hypercortisolism. Furthermore, an increased proatherogenic risk profile is characterized by decreased nitric oxide synthesis and activity, enhanced endothelin‐1 levels and increased proinflammatory markers.
Effects of free fatty acids, growth hormone and growth hormone receptor blockade on serum ghrelin levels in humans
Authors: Gormsen Lars C. , Nielsen Charlotte , Gjedsted Jakob , Gjedde Signe , Vestergaard Esben Thyssen , Christiansen Jens S. , Jørgensen Jens Otto , Møller Niels 
Published: February 2007

SummaryBackground  Circulating ghrelin levels are reported to be suppressed by insulin, GH and free fatty acids (FFAs). However, insulin, GH and FFA levels are all interdependent, and it is therefore difficult to delineate their independent effects on ghrelin secretion.Objective  To isolate and define the impact of GH, GH receptor (GHR) blockade and intravenous FFA infusion on total circulating ghrelin levels during a hyperinsulinaemic glucose clamp with identical insulin levels.Design  In a randomized design, eight healthy males each underwent an 8‐h hyperinsulinaemic glucose clamp on four occasions together with either: (1) control (saline), (2) intravenous FFA infusion (intralipid/heparin infusion 4 h), (3) a GH bolus (0·5 mg i.v.) or (4) GHR blockade (pegvisomant, 30 mg s.c.).Results  Hyperinsulinaemia per se resulted in a decrease in ghrelin concentrations of about 15%. During FFA exposure, ghrelin levels were suppressed by about 22% when compared with saline [area under the curve (AUC)ghrelin0−240 122·7 ± 10·9 vs. 97·6 ± 13·4 pg/ml/min, P = 0·001], followed by a rebound increase upon discontinuation of the infusion. Furthermore, average ghrelin concentration (AUCghrelin) was significantly inversely correlated to average FFA levels (AUCFFA) (r = −0·33, P < 0·05). Neither GH administration nor GHR blockade resulted in significant alterations in total ghrelin levels in the presence of unaltered insulin and FFA levels.Conclusions  Elevation of FFAs by means of an intravenous infusion acutely suppresses ghrelin levels, whereas GH administration and GHR blockade have no detectable effect on ghrelin concentration when insulin and FFA levels are kept fixed.
Linkage of Graves’ disease to the human leucocyte antigen region in the Chinese‐Han population in Taiwan
Authors: Chen Pei‐Lung , Fann Cathy Shen‐Jang , Chang Chien‐Ching , Wu I‐Lin , Chiu Wei‐Yih , Lin Chin‐Yu , Yang Wei‐Shiung , Chang Tien‐Chun 
Published: February 2007

SummaryObjective  To investigate whether markers in the candidate chromosome regions, including the human leucocyte antigen (HLA) region, are linked to Graves’ disease (GD).Design  A familial linkage study with a candidate region approach.Patients  A total of 536 individuals in 122 multiplex Chinese‐Han families with a GD proband and at least one other affected sibling, resulting in 270 affected sib‐pairs. Subjects with a family history of noniatrogenic hypothyroidism or Hashimoto's thyroiditis were excluded.Measurements  We genotyped eight short tandem repeat polymorphism (STRP) markers in a 13·7 cM region covering the HLA region on chromosome 6p21 and 26 STRPs in four other candidate regions previously reported in the literature.Results  Multipoint nonparametric linkage (NPL) analysis showed significant linkage to the HLA region [the marker UniSTS:239159, nonparametric log of odds (LOD) score 3·44, P = 0·00003; NPL Z‐score 4·1, P = 0·00002] from 270 affected sib‐pairs. The 1‐LOD support interval comprised the whole HLA region (ca. 4 Mb). By contrast, the maximal NPL Z‐scores of the markers of the other candidate regions (2q33, 5q31, 7q22 and 14q31) previously reported were all less than 1·0.Conclusions  Our results provide strong support for linkage of GD to the HLA region. Further dissection of this region to identify the candidate gene for GD is warranted in our population.
The impact of salinity pulses on the emergence of plant and zooplankton from wetland seed and egg banks
Authors: NIELSEN DARYL L. , BROCK MARGARET A. , PETRIE ROCHELLE , CROSSLÉ KATHARINE 
Published: February 2007

Summary1. In this study we compared the emergence of aquatic biota from sediments under 14‐day pulses of high (5000 mg L−1) and low (1000 mg L−1) salinity with emergence under freshwater and equivalent constant salinity levels. We tested the hypothesis that pulses of high salinity and short duration have no impact on the emergence of aquatic plants and zooplankton from wetland sediment.2. The way salt is moved through the landscape may alter the response of biota to increases in salinity. Under natural hydrological regimes in rivers and floodplains salinity pulses occur often at concentrations that exceed predicted tolerance levels for aquatic biota. The impacts of natural pulses of high salinity followed by rapid return to fresh conditions may be used to inform management guidelines for the potential release of non‐natural saline water into river systems with minimal impact.3. For both aquatic plants and zooplankton the abundance and richness of the emerging taxa decreased at higher salinities kept at constant levels. In contrast, pulses of salinity followed by return to freshwater conditions did not have a negative impact on the emergence of aquatic plants or zooplankton. For many taxa of zooplankton a positive impact was demonstrated with higher emergence following the salinity pulse.4. The responses of aquatic plant and zooplankton taxa are grouped into five response types. Type 1: negatively impacted by all salt regimes. Type 2: preference for constant salinities. Type 3: no difference between fresh and either pulse regime. Type 4: preference for high concentration pulses. Type 5: emergence higher under a low concentration pulse.5. Although previous studies indicate that constant high‐level salinity in rivers and wetlands can decrease the species richness of aquatic communities, this current study shows pulses may not have the same impact. Our results support the hypothesis that pulses of high salinity and short duration do not impact on the emergence of aquatic plants and zooplankton from wetland sediments. For zooplankton, pulses of salt may trigger emergence.6. These trends may be used to explore the potential to use managed water releases to move salt through the landscape with minimal impact of salinity on aquatic biota. However, before such preliminary results are applied in management of saline water releases we need to determine the implications for interacting processes in natural ecosystems.