bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of α-Amanitin on the Arabidopsis Seed Proteome Highlights the Distinct Roles of Stored and Neosynthesized mRNAs during Germination
Authors: Rajjou Loïc , Gallardo Karine , Debeaujon Isabelle , Vandekerckhove Joël , Job Claudette , Job Dominique 
Published: April 2004

Abstract
To investigate the role of stored and neosynthesized mRNAs in seed germination, we examined the effect of α-amanitin, a transcriptional inhibitor targeting RNA polymerase II, on the germination of nondormant Arabidopsis seeds. We used transparent testa mutants, of which seed coat is highly permeable, to better ascertain that the drug can reach the embryo during seed imbibition. Even with the most permeable mutant (tt2-1), germination (radicle protrusion) occurred in the absence of transcription, while subsequent seedling growth was blocked. In contrast, germination was abolished in the presence of the translational inhibitor cycloheximide. Taken together, the results highlight the role of stored proteins and mRNAs for germination in Arabidopsis and show that in this species the potential for germination is largely programmed during the seed maturation process. The α-amanitin-resistant germination exhibited characteristic features. First, this germination was strongly slowed down, indicating that de novo transcription normally allows the synthesis of factor(s) activating the germination rate. Second, the sensitivity of germination to gibberellic acid was reduced 15-fold, confirming the role of this phytohormone in germination. Third, de novo synthesis of enzymes involved in reserve mobilization and resumption of metabolic activity was repressed, thus accounting for the failure in seedling establishment. Fourth, germinating seeds can recapitulate at least part of the seed maturation program, being capable of using mRNAs stored during development. Thus, commitment to germination and plant growth requires transcription of genes allowing the imbibed seed to discriminate between mRNAs to be utilized in germination and those to be destroyed.
Partial Purification, Kinetic Analysis, and Amino Acid Sequence Information of a Flavonol 3-O-Methyltransferase from Serratula tinctoria
Authors: Huang Tyng-Shyan , Anzellotti Dominique , Dedaldechamp Fabienne , Ibrahim Ragai K. 
Published: April 2004

Abstract
Serratula tinctoria (Asteraceae) accumulates mainly 3,3′-dimethylquercetin and small amounts of 3-methylquercetin as an intermediate. The fact that 3-methylquercetin rarely accumulates in plants in significant amounts, and given its important role as an antiviral and antiinflammatory agent that accumulates in response to stress conditions, prompted us to purify and characterize the enzyme involved in its methylation. The flavonol 3-O-methyltransferase (3-OMT) was partially purified by ammonium sulfate precipitation and successive chromatography on Superose-12, Mono-Q, and adenosine-agarose affinity columns, resulting in a 194-fold increase of its specific activity. The enzyme protein exhibited an expressed specificity for the methylation of position 3 of the flavonol, quercetin, although it also utilized kaempferol, myricetin, and some monomethyl flavonols as substrates. It exhibited a pH optimum of 7.6, a pI of 6.0, and an apparent molecular mass of 31 kD. Its K m values for quercetin as the substrate and S-adenosyl-l-Met (AdoMet) as the cosubstrate were 12 and 45 μ m, respectively. The 3-OMT had no requirement for Mg2+, but was severely inhibited by p-chloromercuribenzoate, suggesting the requirement for SH groups for catalytic activity. Quercetin methylation was competitively inhibited by S-adenosyl-l-homo-Cys with respect to the cosubstrate AdoMet, and followed a sequential bi-bi reaction mechanism, where AdoMet was the first to bind and S-adenosyl-l-homo-Cys was released last. In-gel trypsin digestion of the purified protein yielded several peptides, two of which exhibited strong amino acid sequence homology, upon protein identification, to a number of previously identified Group II plant OMTs. The availability of peptide sequences will allow the design of specific nucleotide probes for future cloning of the gene encoding this novel enzyme for its use in metabolic engineering.
Tissue-Specific Localization of an Abscisic Acid Biosynthetic Enzyme, AAO3, in Arabidopsis
Authors: Koiwai Hanae , Nakaminami Kentaro , Seo Mitsunori , Mitsuhashi Wataru , Toyomasu Tomonobu , Koshiba Tomokazu 
Published: April 2004

Abstract
Arabidopsis aldehyde oxidase 3 (AAO3) is an enzyme involved in abscisic acid (ABA) biosynthesis in response to drought stress. Since the enzyme catalyzes the last step of the pathway, ABA production sites may be determined by the presence of AAO3. Here, AAO3 localization was investigated using AAO3 promoter:AAO3-GFP transgenic plants and by an immunohistochemical technique. AAO3-GFP protein exhibited an activity to produce ABA from abscisic aldehyde, and the transgene restored the wilty phenotype of the aao3 mutant. GFP-fluorescence was detected in the root tips, vascular bundles of roots, hypocotyls and inflorescence stems, and along the leaf veins. Intense immunofluorescence signals were localized in phloem companion cells and xylem parenchyma cells. Faint but significant GFP- and immuno-fluorescence signals were observed in the leaf guard cells. In situ hybridization with antisense AAO3 mRNA showed AAO3 mRNA expression in the guard cells of dehydrated leaves. These results indicate that the ABA synthesized in vascular systems is transported to various target tissues and cells, and also that the guard cells themselves are able to synthesize ABA.
Potato Virus X-Induced Gene Silencing in Leaves and Tubers of Potato
Authors: Faivre-Rampant Odile , Gilroy Eleanor M. , Hrubikova Katarina , Hein Ingo , Millam Steve , Loake Gary J. , Birch Paul , Taylor Mark , Lacomme Christophe 
Published: April 2004

Abstract
Virus induced gene silencing (VIGS) is increasingly used to generate transient loss-of-function assays and has potential as a powerful reverse-genetics tool in functional genomic programs as a more rapid alternative to stable transformation. A previously described potato virus X (PVX) VIGS vector has been shown to trigger silencing in the permissive host Nicotiana benthamiana. This paper demonstrates that a PVX-based VIGS vector is also effective in triggering a VIGS response in both diploid and cultivated tetraploid Solanum species. We show that systemic silencing of a phytoene desaturase gene is observed and maintained throughout the foliar tissues of potato plants and was also observed in tubers. Here we report that VIGS can be triggered and sustained on in vitro micropropagated tetraploid potato for several cycles and on in vitro generated microtubers. This approach will facilitate large-scale functional analysis of potato expressed sequence tags and provide a noninvasive reverse-genetic approach to study mechanisms involved in tuber and microtuber development.
TOUSLED Kinase Activity Oscillates during the Cell Cycle and Interacts with Chromatin Regulators
Authors: Ehsan Hashimul , Reichheld Jean-Philippe , Durfee Tim , Roe Judith L. 
Published: April 2004

Abstract
The TOUSLED (TSL)-like nuclear protein kinase family is highly conserved in plants and animals. tsl loss of function mutations cause pleiotropic defects in both leaf and flower development, and growth and initiation of floral organ primordia is abnormal, suggesting that basic cellular processes are affected. TSL is more highly expressed in exponentially growing Arabidopsis culture cells than in stationary, nondividing cells. While its expression remains constant throughout the cell cycle in dividing cells, TSL kinase activity is higher in enriched late G2/M-phase and G1-phase populations of Arabidopsis suspension culture cells compared to those in S-phase. tsl mutants also display an aberrant pattern and increased expression levels of the mitotic cyclin gene CycB1;1, suggesting that TSL represses CycB1;1 expression at certain times during development or that cells are delayed in mitosis. TSL interacts with and phosphorylates one of two Arabidopsis homologs of the nucleosome assembly/silencing protein Asf1 and histone H3, as in humans, and a novel plant SANT/myb-domain protein, TKI1, suggesting that TSL plays a role in chromatin metabolism.
Functional Analysis of the Final Steps of the 1-Deoxy-d-xylulose 5-phosphate (DXP) Pathway to Isoprenoids in Plants Using Virus-Induced Gene Silencing
Authors: Page Jonathan E. , Hause Gerd , Raschke Maja , Gao Wenyun , Schmidt Jürgen , Zenk Meinhart H. , Kutchan Toni M. 
Published: April 2004

AbstractIsoprenoid biosynthesis in plant plastids occurs via the 1-deoxy-d-xylulose 5-phosphate (DXP) pathway. We used tobacco rattle virus (TRV) to posttranscriptionally silence the expression of the last two enzymes of this pathway, the IspG-encoded (E)-4-hydroxy-3-methylbut-2-enyl diphosphate synthase (HDS) and the IspH-encoded isopentenyl/dimethylallyl diphosphate synthase (IDDS), as well as isopentenyl/dimethylallyl diphosphate isomerase (IDI), the enzyme that interconverts IPP and DMAPP. TRV-IspG and TRV-IspH infected Nicotiana benthamiana plants had albino leaves that contained less than 4% of the chlorophyll and carotenoid pigments of control leaves. We applied [13C]DXP and [14C]DXP to silenced leaves and found that 2-C-methyl-d-erythritol 2,4-cyclodiphosphate accumulated in plants blocked at HDS while DXP, (E)-4-hydroxy-3-methylbut-2-enyl phosphate and (E)-2-methylbut-2-ene-1,4-diol accumulated in IDDS-blocked plants. Albino leaves from IspG- and IspH-silenced plants displayed a disorganized palisade mesophyll, reduced cuticle, fewer plastids, and disrupted thylakoid membranes. These findings demonstrate the participation of HDS and IDDS in the DXP pathway in plants, and support the view that plastid isoprenoid biosynthesis is metabolically and physically segregated from the mevalonate pathway. IDI-silenced plants had mottled white-pale green leaves with disrupted tissue and plastid structure, and showed an 80% reduction in pigments compared to controls. IPP pyrophosphatase activity was higher in chloroplasts isolated from IDI-silenced plants than in control plant chloroplasts. We suggest that a low level of isoprenoid biosynthesis via the DXP pathway can occur without IDI but that this enzyme is required for full function of the DXP pathway.
Adenylate Gradients and Ar:O2 Effects on Legume Nodules. II. Changes in the Subcellular Adenylate Pools
Authors: Wei Hui , Atkins Craig A. , Layzell David B. 
Published: April 2004

Abstract
Central infected zone tissue of soybean (Glycine max L. Merr.) nodules was fractionated into separate subcellular compartments using density gradient centrifugation in nonaqueous solvents to better understand how exposure to Ar:O2 (80:20%, v/v) atmosphere affects C and N metabolism, and to explore a potential role for adenylates in regulating O2 diffusion. When nodules were switched from air to Ar:O2, adenylate energy charge (AEC) in the plant cytosol rose from 0.63 ± 0.02 to 0.73 ± 0.02 within 7 min and to 0.80 ± 0.01 by 60 min. In contrast, AEC of the mitochondrial compartment of this central zone tissue remained high (0.80 ± 0.02 to 0.81 ± 0.02) following Ar treatment while that of the bacteroid compartment was unchanged, at 0.73 ± 0.02, after 7 min, but declined to 0.57 ± 0.03 after 60 min. These results were consistent with a simulation model that predicted Ar:O2 exposure would first reduce ATP demand for ammonia assimilation and rapidly increase cytosolic AEC, before the Ar:O2-induced decline mediated by a decrease in nodule O2 permeability reduces bacteroid AEC. The possibility that adenylates play a key, integrating role in regulating nodule permeability to oxygen diffusion is discussed.
Skin Diseases in Chinese Children at a Pediatric Dermatology Center
Authors: Hon Kam Lun , Leung Ting Fan , Wong Yin , Ma Kwok Chiu , Fok Tai Fai 
Published: April 2004

Abstract:  Understanding the pattern of disease referrals is important in the delivery of a service. We followed 331 new referrals at a pediatric dermatology clinic over 12 months. Fifty percent of the patients were female; 293 patients (88.5%) had a single diagnosis and 36 (10.9%) had two diagnoses. Three leading causes for referrals accounted for 60% of the 371 skin diseases encountered: 124 diagnoses (33%) were of eczema, 73 diagnoses (20%) were of nevi, and 22 diagnoses (6%) were of viral warts. The nevi seen included melanocytic, epidermal, sebaceous, and vascular nevi. Skin biopsies were performed in 23 patients (6.9%), and microscopy and culture for fungal infections in 11 patients (3.3%). Forty‐one patients (12%) were referred to the laser clinic for assessment of their nevi or pigmented skin lesions. Topical steroids were prescribed in 47% of patients during their follow‐ups. Follow‐up appointments were offered to 90% of patients. Eczema required the most frequent follow‐up. Gender disparity in referrals was evident only in endogenous eczema (odds ratio [OR] 1.64, 95% confidence interval [CI] 1.04–2.60 in males; p = 0.033). Girls were more likely to be referred to the laser clinic than boys (OR 2.31, 95% CI 1.10–4.92; p = 0.026). Most dermatologic diagnoses were made on clinical grounds and moderately potent topical corticosteroids were the most commonly prescribed medication. Since chronic skin disorders prevailed in the referrals, repeated follow‐up appointments were required.
Chloroplast development affects expression of phage‐type RNA polymerases in barley leaves
Authors: Emanuel Carola , Weihe Andreas , Graner Andreas , Hess Wolfgang R. , Börner Thomas 
Published: April 2004

SummaryWe have identified the barley gene and cDNA encoding the plastid phage‐type RNA polymerase (RNAP), nuclear‐encoded plastid RNAP (RpoTp), and the nearly full‐length cDNA of the mitochondrial RNAP, nuclear‐encoded mitochondrial RNAP (RpoTm). RpoTp spans more than 9000 nt, consists of 19 exons and 18 introns, gives rise to a 3632‐nt mRNA and is localized to the long arm of chromosome 1 (7H). The length of the deduced polypeptide is 948 residues. The mRNA levels of RpoTp and RpoTm were determined in roots and primary leaf sections of 7‐day‐old barley seedlings of the albostrians mutant, which were either phenotypically normal and exhibited a gradient of chloroplast development, or contained ribosome‐deficient undifferentiated plastids. Transcript levels of RpoTp and RpoTm in almost all sections reached higher concentrations in plastid ribosome‐deficient leaves than in the wild‐type material, except in the most basal part of the leaf. These data indicate a role of plastid‐to‐nucleus signalling in the expression of the two RpoT genes. The mRNA levels of the plastid genes, β‐subunit of plastid‐encoded RNAP (rpoB), proteolytic subunit of the Clp protease (clpP) and ribosomal protein Rpl2 (rpl2), all known to be transcribed by the nuclear‐encoded RNAP (NEP), followed closely the pattern of RpoTp mRNA accumulation, strongly suggesting that RpoTp and NEP are identical. Transcripts of RpoTm and RpoTm‐transcribed mitochondrial genes cytochrome oxidase subunit 2 (coxII) and ATPase subunit 9 (atp9) accumulated to the highest levels in the most basal parts of the leaf and declined considerably towards the leaf tip with a pronounced reduction in green versus white leaves. Our data revealed a marked influence of the developmental stage of the plastid on the expression and activity of organellar phage‐type RNAPs and their target genes. Thus, interorganellar cross‐talk in the regulated expression of nuclear‐encoded plastid and mitochondrial RNAP genes might be a key element governing the concerted expression of genes located within plastids, mitochondria and the nucleus of the plant cell.
Oxidative burst and expression of germin/oxo genes during wounding of ryegrass leaf blades: comparison with senescence of leaf sheaths
Authors: Le Deunff Erwan , Davoine Céline , Le Dantec Christelle , Billard Jean‐Pierre , Huault Claude 
Published: April 2004

SummaryTwo bursts of H2O2 production have been detected by in situ 3,3′‐diaminobenzidine (DAB) staining after cutting of Lolium perenne L. leaf blades. The first burst, which occurred immediately after wounding was inhibited by Na‐diethydithiocarbamate (DIECA), a Cu/Zn–superoxide dismutase (SOD) inhibitor. The second burst, which was initiated several hours later, coincided with the induction of oxalate oxidase (G‐OXO) activity detected in vitro or visualized in situ by the α‐chloronaphtol assay. Four genes encoding G‐OXO have been identified from cDNA obtained from wounded L. perenne L. leaf blades. Comparison of protein sequences revealed more than 91% homology in the coding region between G‐OXOs of the true cereals and G‐OXOs of ryegrass, which is a Gramineae belonging to the tribe of Festucaceae. The wound‐dependent increase of G‐OXO activity in floated cut leaf blades was the result of differential induction of the four g‐oxo genes. The involvement of G‐OXOs in wound‐induced H2O2 production coincided with the presence in leaf tissues of oxalate throughout the period of increase of G‐OXO synthesis. Moreover, expression of g‐oxo genes was enhanced by an exogenous supply of H2O2 or methyljasmonate (MeJa). Expression of the four g‐oxo genes was also induced after in planta stinging of leaf blades. The pattern of their expression in planta was identical to that occuring in senescing leaf sheaths. These results emphasize the importance of G‐OXOs in H2O2 production in oxalate‐producing plant species such as ryegrass. G‐OXOs might be crucial during critical events in the life of plants such as cutting and senescence by initiating H2O2‐mediated defences against pathogens and foraging animals.
A mutation of the CRUMPLED LEAF gene that encodes a protein localized in the outer envelope membrane of plastids affects the pattern of cell division, cell differentiation, and plastid division in Arabidopsis
Authors: Asano Tomoya , Yoshioka Yasushi , Kurei Shunsuke , Sakamoto Wataru ,   Sodmergen, Machida Yasunori 
Published: April 2004

SummaryWe identified a novel mutation of a nuclear‐encoded gene, designated as CRUMPLED LEAF (CRL), of Arabidopsis thaliana that affects the morphogenesis of all plant organs and division of plastids. Histological analysis revealed that planes of cell division were distorted in shoot apical meristems (SAMs), root tips, and embryos in plants that possess the crl mutation. Furthermore, we observed that differentiation patterns of cortex and endodermis cells in inflorescence stems and root endodermis cells were disturbed in the crl mutant. These results suggest that morphological abnormalities observed in the crl mutant were because of aberrant cell division and differentiation. In addition, cells of the crl mutant contained a reduced number of enlarged plastids, indicating that the division of plastids was inhibited in the crl. The CRL gene encodes a novel protein with a molecular mass of 30 kDa that is localized in the plastid envelope. The CRL protein is conserved in various plant species, including a fern, and in cyanobacteria, but not in other organisms. These data suggest that the CRL protein is required for plastid division, and it also plays an important role in cell differentiation and the regulation of the cell division plane in plants. A possible function of the CRL protein is discussed.
A Malar Granular Cell Tumor in a Djungarian Hamster
Authors: Sato T. , Takada M. , Shibuya H. , Shirai W. , Matsuo K. 
Published: April 2004

Summary‘Granular cell’ tumor observed in the malar subcutis of a Djungarian hamster was examined to determine its cellular origin. Histologically, the tumor consisted of a solid growth of oval or spindle‐shaped large cells with abundant cytoplasm filled with eosinophilic granules that were periodic acid‐Schiff‐positive and diastase‐resistant. Immunohistochemically, the tumor cells were positive to anti‐vimentin and anti‐desmin antibodies and a few cells showed positivity to anti‐actin antibody as well. They did not react to myoglobin, S‐100 protein, and glial fibrillary acidic protein (GFAP). Electron microscopic studies revealed that the tumor cells had pinocytotic vesicles, dense plaque and microfilaments. The first granular cell variant of myogenic tumor reported here in Djungarian hamsters was differentiated from granular cell tumor of Schwann cell origin.
Pregnancy Rate after Timed Artificial Insemination in Early Post‐partum Dairy Cows after Ovsynch or Specific Synchronization Protocols
Authors: Lòpez‐Gatius F. , Murugavel K. , Santolaria P. , López‐Béjar M. , Yániz J. L. 
Published: April 2004

SummaryThe present study was designed to compare the reproductive performance of pre‐synchronized post‐partum dairy cows subjected, either to the Ovsynch protocol without screening for ovarian status (control group), or to a specific oestrous synchronization protocol applied according to their ovarian status, as determined by transrectal ultrasound (experimental group). The study was conducted on 428 lactating dairy cows. Cows in the Ovsynch group (n = 205) were synchronized and time inseminated after receiving the Ovsynch protocol treatment. Cows in the specific synchronization (Ssynch) group (n = 223) were weekly subjected to transrectal ultrasound exams for 4 weeks, or until AI or starting treatment, and divided into four subgroups according to their ovarian status: (i) corpus luteum (CL) subgroup (n = 130), cows with a CL; (ii) natural oestrus (NE) subgroup (n = 58), cows showing NE; (iii) anovulatory follicles (AF) subgroup (n = 26), cows considered to have AF; and (iv) ovarian cysts (OC) subgroup (n = 9), cows with OC. Cows in the Ssynch group were synchronized and time inseminated following a specific oestrous synchronization protocol, or inseminated at NE. Logistic regression analysis was carried out for the dependent variables ovulation and pregnancy rates to first and to second AI (second AI: first AI + return AI). Cows subjected to Ssynch were 2.1 times more likely to become pregnant at first and at second AI compared with those synchronized using the Ovsynch protocol (P < 0.0001). Our results show that the response of post‐partum pre‐synchronized cows to a specific oestrous synchronization protocol applied according to their ovarian status is more effective than the response to the Ovsynch protocol applied without taking into account the ovarian status of the animals.
Immunohistopathological Findings in the Lungs of Calves Naturally Infected with Mycoplasma bovis
Authors: Khodakaram‐Tafti A. , López A. 
Published: April 2004

SummaryHistology and immunohistochemistry were used to analyse the lesions and distribution of Mycoplasma bovis antigen in the lungs of 18 naturally infected calves. Microscopic examination of pneumonic lungs revealed two distinct patterns of necrosis and inflammation. The first pattern was observed in six of 18 (33.3%) calves in which microscopic lesions were characterized by large irregular areas of coagulative necrosis surrounded by a dense zone of degenerated neutrophils. Moderate amounts of mycoplasmal antigen were in the centre and periphery of these necrotic foci and, to a lesser extent, in mononuclear cells of the peribronchial lymphoid tissue. The second pattern was observed in 18 of 18 (100%) calves and consisted of rounded foci of caseous necrosis composed by granular eosinophilic material surrounded by a rim of granulation tissue. Large amounts of M. bovis antigen were detected in the centre and periphery of these necrotic foci and, to a lesser extent, in the peribronchial lymphoid tissue, and alveolar and interstitial macrophages. It was concluded that both caseous and coagulative necrosis of the lung parenchyma was primarily caused by M. bovis. Infection with M. bovis should be suspected in bovine necrotic bronchopneumonia, particularly in cases in which the pulmonary necrosis is part of a pyogranulomatous inflammation centred around airways. The pattern of caseous necrosis with pyogranulomatous inflammation is characteristic of M. bovis infection while the pattern of coagulative necrosis is similar to and must be differentiated from Mannheimia haemolytica and Haemophilus somnus infection.