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1.
BMC Psychiatry ; 23(1): 65, 2023 01 25.
Article in English | MEDLINE | ID: mdl-36694179

ABSTRACT

BACKGROUND: Potentially traumatic events may lead to the development of a wide range of adverse psychological responses, including symptoms of anxiety, depression, and (complex) posttraumatic stress disorder (PTSD). Despite the high prevalence of potentially traumatic events in Iran, there is no population data nor evidence-based instrument to screen for cross-diagnostic psychological responses to trauma. The Global Psychotrauma Screen (GPS) is a transdiagnostic self-report instrument for the detection of trauma-related symptoms, as well as risk and protective factors related to the impact of potentially traumatic events. OBJECTIVE: The present study seeks to 1) translate and cross-culturally adapt the GPS in the Persian (Farsi) language and 2) examine the psychometric properties of the Persian GPS. METHOD: The translation and adaptation were performed using the Sousa and Rojjanasrirat (2011) method. A pilot study (n = 30) was carried out to test the content validity and test-retest reliability of the GPS. Next, in a representative sample (n = 800) of residents of Kermanshah City, the GPS, the General Health Questionnaire (GHQ) and the PTSD Checklist for DSM-5 (PCL-5) were administered. Construct validity of the Persian GPS was assessed using exploratory and confirmatory factor analysis. Additionally, we evaluated the convergent validity and internal consistency of the GPS. RESULTS: Exploratory and confirmatory factor analyses indicated a three-factor model as the best solution with factors representing 1) Negative Affect, 2) Core PTSD symptoms and 3) Dissociative symptoms. The GPS total symptom score had high internal consistency and high convergent validity with related measures. A GPS total symptom cut-off score of nine was optimal for indicating a probable PTSD diagnosis based on the PCL-5. About half (52%) of the current sample met criteria for probable PTSD. CONCLUSIONS: The current findings suggest that the GPS can be effectively adapted for use in a non-Western society and, specifically, that the Persian GPS represents a useful, reliable and valid tool for screening of trauma-related symptoms in Iran.


Subject(s)
Cross-Cultural Comparison , Stress Disorders, Post-Traumatic , Humans , Reproducibility of Results , Iran , Pilot Projects , Stress Disorders, Post-Traumatic/diagnosis , Stress Disorders, Post-Traumatic/psychology , Psychometrics
2.
Protoplasma ; 215(1-4): 116-27, 2001.
Article in English | MEDLINE | ID: mdl-11732051

ABSTRACT

The rsw1 mutant of Arabidopsis thaliana is mutated in a gene encoding a cellulose synthase catalytic subunit. Mutant seedlings produce almost as much cellulose as the wild type at 21 degrees C but only about half as much as the wild type at 31 degrees C. We used this conditional phenotype to investigate how reduced cellulose production affects growth and morphogenesis in various parts of the plant. Roots swell in all tissues at 31 degrees C, and temperature changes can repeatedly switch them between swollen and slender growth patterns. Dark-grown hypocotyls also swell, whereas cotyledons and rosette leaf blades are smaller, their surfaces are more irregular and their petioles shorter. Leaf trichomes swell and branch abnormally. Plants readily initiate inflorescences at 31 degrees C which have shorter but not fatter bolts and stomata which bulge above the uneven surface of internodes. Bolts carry the normal number of flowers, but their stigmas protrude beyond the shortened sepals and petals. Anthers dehisce normally, but self-fertilisation is reduced because the stigma is well above the anthers. Anther filaments are short and show a crumpled surface. Viable pollen develops, but female reproductive competence and postpollination development are severely impaired. We conclude that the RSW1 gene is important for cellulose synthesis in many parts of the plant and that reduced cellulose synthesis suppresses organ expansion rather than organ initiation, causes radial swelling only in the root and hypocotyl, but makes the surfaces of many organs uneven. We discuss some possible reasons to explain why different organs vary in their responses. The morphological changes suggest that RSW1 contributes cellulose to primary walls but do not yet exclude a role during secondary-wall deposition.


Subject(s)
Arabidopsis/anatomy & histology , Arabidopsis/growth & development , Cellulose/metabolism , Glucosyltransferases/metabolism , Arabidopsis/enzymology , Arabidopsis/genetics , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Genes, Plant , Glucosyltransferases/genetics , Mutation , Phenotype , Plant Structures/anatomy & histology , Plant Structures/metabolism , Plant Structures/ultrastructure , Temperature
3.
Protoplasma ; 215(1-4): 172-83, 2001.
Article in English | MEDLINE | ID: mdl-11732056

ABSTRACT

The rsw1 mutant of Arabidopsis thaliana has a single amino acid substitution in a putative glycosyl transferase that causes a temperature-dependent reduction in cellulose production. We used recently described methods to examine root growth by surface marker particles, cell wall structure by field emission scanning electron microscopy and microtubule alignment by immunofluorescence after the mutant is transferred to its restrictive temperature. We find that raising the temperature quickly accelerates root elongation in both wild type and mutant, presumably as a result of general metabolic stimulation, but that in the mutant, the rate declines within 7-8 h and elongation almost ceases after 24 h. Radial swelling begins at about 6 h in the mutant and root diameter continues to increase until about 24 h. The normal transverse alignment of microfibrils is severely impaired in the mutant after 8 h, and chemical inhibition of cellulose synthesis by 2,6-dichlorobenzonitrile causes a similar loss of orientation. After 24 h, microfibrils are not clearly visible in the walls of cells that would have been in the mitotic and early-elongation zone of wild-type roots. Changes in older cells are less marked; loss of transverse microfibril orientation occurs without disruption to the transverse orientation of cortical microtubules. The wild type shows none of the changes except for acceleration of elongation, which in its case is sustained. We conclude that microfibril alignment requires the normal functioning of RSW1 and that, in view of the effects of dichlorobenzonitrile, there may be a more general linkage between the rate of cellulose production and its proper alignment.


Subject(s)
Arabidopsis Proteins , Arabidopsis/ultrastructure , Cell Wall/ultrastructure , Glucosyltransferases/metabolism , Microfibrils/ultrastructure , Microtubules/ultrastructure , Plant Roots/ultrastructure , Arabidopsis/chemistry , Arabidopsis/genetics , Arabidopsis/growth & development , Cell Polarity , Cell Wall/chemistry , Cellulose/analysis , Genes, Plant , Glucosyltransferases/genetics , Microfibrils/chemistry , Microtubules/chemistry , Mitosis , Mutation , Plant Roots/chemistry
4.
Cell Mol Life Sci ; 58(10): 1475-90, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11693528

ABSTRACT

Cellulose microfibrils containing crystalline beta-1,4-glucan provide the major structural framework in higher-plant cell walls. Genetic analyses of Arabidopsis thaliana now link specific genes to plant cellulose production just as was achieved some years earlier with bacteria. Cellulose-deficient mutants have defects in several members of one family within a complex glycosyltransferase superfamily and in one member of a small family of membrane-bound endo-1,4-beta-glucanases. The mutants also accumulate a readily extractable beta-1,4-glucan that has short chains which, in at least one case, are lipid linked. Cellulose could be made by direct extension of the glucan chain by the glycosyltransferase or, as the mutant suggests, by an indirect route which makes lipid-linked oligosaccharides. Models discussed incorporate the known enzymes and lipo-glucan and raise the possibility that different CesA glycosyltransferases may catalyse different steps.


Subject(s)
Arabidopsis/chemistry , Arabidopsis/genetics , Cellulose/biosynthesis , Catalysis , Cell Membrane/metabolism , Cell Wall/chemistry , Cellulase/biosynthesis , DNA Mutational Analysis , Genome, Bacterial , Glycosyltransferases/chemistry , Models, Biological , Models, Chemical , Models, Genetic , Mutation , Polysaccharides/biosynthesis , Protein Binding
5.
Am J Hum Genet ; 69(5): 923-35, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11577373

ABSTRACT

As auditory genes and deafness-associated mutations are discovered at a rapid rate, exciting opportunities have arisen to uncover the molecular mechanisms underlying hearing and hearing impairment. Single genes have been identified to be pathogenic for dominant or recessive forms of nonsyndromic hearing loss, syndromic hearing loss, and, in some cases, even multiple forms of hearing loss. Modifier loci and genes have been found, and investigations into their role in the hearing process will yield valuable insight into the fundamental processes of the auditory system.


Subject(s)
Deafness/genetics , Hearing/genetics , Deafness/metabolism , Deafness/physiopathology , Extracellular Matrix/metabolism , Homeostasis , Humans , Ions/metabolism , Mutation , Phenotype , Transcription Factors/metabolism
6.
Plant Physiol ; 126(1): 278-88, 2001 May.
Article in English | MEDLINE | ID: mdl-11351091

ABSTRACT

An 8.5-kb cosmid containing the KORRIGAN gene complements the cellulose-deficient rsw2-1 mutant of Arabidopsis. Three temperature-sensitive alleles of rsw2 show single amino acid mutations in the putative endo-1,4-beta-glucanase encoded by KOR. The F1 from crosses between kor-1 and rsw2 alleles shows a weak, temperature-sensitive root phenotype. The shoots of rsw2-1 seedlings produce less cellulose and accumulate a short chain, readily extractable glucan resembling that reported for rsw1 (which is defective in a putative glycosyltransferase required for cellulose synthesis). The double mutant (rsw2-1 rsw1) shows further reductions in cellulose production relative to both single mutants, constitutively slow root growth, and enhanced temperature-sensitive responses that are typically more severe than in either single mutant. Abnormal cytokinesis and severely reduced birefringent retardation in elongating root cell walls of rsw2 link the enzyme to cellulose production for primary cell walls and probably cell plates. The Rsw2(-) phenotype generally resembles the Kor(-) and cellulose-deficient Rsw1(-) phenotypes, but anther dehiscence is impaired in Rsw2-1(-). The findings link a second putative enzyme activity to cellulose synthesis in primary cell walls of Arabidopsis and further increases the parallels to cellulose synthesis in Agrobacterium tumefaciens where the celA and celC genes are required and encode a putative glycosyltransferase and an endo-1,4-beta-glucanase related to RSW1 and KOR, respectively.


Subject(s)
Alleles , Arabidopsis/metabolism , Cell Cycle , Cellulase/metabolism , Cellulose/biosynthesis , Plant Proteins/genetics , Arabidopsis/cytology , Arabidopsis/enzymology , Cellulase/genetics , Microscopy, Electron, Scanning , Phenotype , Plant Roots/growth & development , Plant Roots/ultrastructure , Temperature
7.
Plant Physiol ; 124(4): 1493-506, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11115865

ABSTRACT

This article explores root epidermal cell elongation and its dependence on two structural elements of cells, cortical microtubules and cellulose microfibrils. The recent identification of Arabidopsis morphology mutants with putative cell wall or cytoskeletal defects demands a procedure for examining and comparing wall architecture and microtubule organization patterns in this species. We developed methods to examine cellulose microfibrils by field emission scanning electron microscopy and microtubules by immunofluorescence in essentially intact roots. We were able to compare cellulose microfibril and microtubule alignment patterns at equivalent stages of cell expansion. Field emission scanning electron microscopy revealed that Arabidopsis root epidermal cells have typical dicot primary cell wall structure with prominent transverse cellulose microfibrils embedded in pectic substances. Our analysis showed that microtubules and microfibrils have similar orientation only during the initial phase of elongation growth. Microtubule patterns deviate from a predominantly transverse orientation while cells are still expanding, whereas cellulose microfibrils remain transverse until well after expansion finishes. We also observed microtubule-microfibril alignment discord before cells enter their elongation phase. This study and the new technology it presents provide a starting point for further investigations on the physical properties of cell walls and their mechanisms of assembly.


Subject(s)
Arabidopsis/metabolism , Cell Wall/metabolism , Microtubules/metabolism , Plant Roots/growth & development , Arabidopsis/growth & development , Arabidopsis/ultrastructure , Cell Wall/ultrastructure , Cellulose/metabolism , Fluorescent Antibody Technique , Microscopy, Confocal , Microscopy, Electron, Scanning/methods , Plant Roots/cytology , Plant Roots/ultrastructure
8.
Plant Physiol ; 124(2): 813-22, 2000 Oct.
Article in English | MEDLINE | ID: mdl-11027729

ABSTRACT

We conducted kinematic and cytological studies on "between vein" epidermal cells of the gibberellin (GA)-deficient M489 dwarf mutant of barley (Hordeum vulgare L. Himalaya). GAs affect radial and axial components of cell expansion and cortical microtubule orientation. Adaxial cells in particular expand radially after leaving the elongation zone (EZ), probably as part of leaf unrolling. Exogenous gibberellic acid corrects the mutant's short, wide blades, short EZ, and slow elongation rate. Cell production rates increase more on the adaxial than on the abaxial surface. Cells spend equal periods of time elongating in dwarf and tall plants, but relative elemental growth rates start to decline sooner in the dwarf. GA increased the rate at which longitudinal wall area increased because the increased axial growth more than compensated for reduced radial growth. In dwarf leaves, increased radial expansion was detected in basal parts of the EZ before cortical microtubules lost transverse orientation in the distal elongation zone. We conclude that loss of microtubule orientation is not required for low GA levels to reduce growth anisotropy.


Subject(s)
Gibberellins/metabolism , Gibberellins/pharmacology , Hordeum/growth & development , Hordeum/metabolism , Hordeum/drug effects , Hordeum/genetics , Meristem/drug effects , Meristem/growth & development , Meristem/metabolism , Microscopy, Confocal , Microtubules/drug effects , Mutation , Plant Leaves/drug effects , Plant Leaves/growth & development , Plant Leaves/metabolism
9.
Planta ; 211(3): 406-14, 2000 Aug.
Article in English | MEDLINE | ID: mdl-10987560

ABSTRACT

Three non-allelic radial swelling mutants (rsw1, rsw2 and rsw3) of Arabidopsis thaliana L. Heynh. were shown to be specifically impaired in cellulose production. Fractionation methods that identify, characterise and quantify some of the major cell wall polysaccharides in small quantities of seedlings demonstrated that changes in the production of cellulose are much more pronounced than changes in the production of non-cellulosic polysaccharides. A crude cell wall pellet was sequentially extracted with chloroform methanol (to recover lipids), dimethyl sulphoxide (starch), ammonium oxalate (pectins) and alkali (hemicelluloses). Crystalline cellulose remained insoluble through subsequent treatments with an acetic/nitric acid mixture and with trifluoroacetic acid. Cetyltrimethylammonium bromide precipitation resolved neutral and acidic polymers in the fractions, and precipitation behaviour, monosaccharide composition and glycosidic linkage patterns identified the major polysaccharides. The deduced composition of the walls of wild-type seedlings and the structure and solubility properties of the major polymers were broadly typical of other dicots. The three temperature-sensitive, radial swelling mutants produced less cellulose in their roots than the wild type when grown at their restrictive temperature (31 degrees C). There were no significant differences at 21 degrees C where no radial swelling occurs. The limited changes seen in the monosaccharide compositions, glycosidic linkage patterns and quantities of non-cellulosic polysaccharides support the view that the RSW1, RSW2 and RSW3 genes are specifically involved in cellulose synthesis. Reduced deposition of cellulose was accompanied by increased accumulation of starch.


Subject(s)
Arabidopsis/metabolism , Carbohydrate Metabolism , Cellulose/biosynthesis , Plant Roots/metabolism , Polysaccharides/biosynthesis , Arabidopsis/cytology , Arabidopsis/genetics , Carbohydrates/isolation & purification , Colorimetry , Gas Chromatography-Mass Spectrometry , Plant Roots/cytology
10.
Proc Natl Acad Sci U S A ; 97(2): 571-6, 2000 Jan 18.
Article in English | MEDLINE | ID: mdl-10639120

ABSTRACT

The Parkinson's disease (PD) substantia nigra is characterized by the presence of Lewy bodies containing fibrillar alpha-synuclein. Early-onset PD has been linked to two point mutations in the gene that encodes alpha-synuclein, suggesting that disease may arise from accelerated fibrillization. However, the identity of the pathogenic species and its relationship to the alpha-synuclein fibril has not been elucidated. In this in vitro study, the rates of disappearance of monomeric alpha-synuclein and appearance of fibrillar alpha-synuclein were compared for the wild-type (WT) and two mutant proteins, as well as equimolar mixtures that may model the heterozygous PD patients. Whereas one of the mutant proteins (A53T) and an equimolar mixture of A53T and WT fibrillized more rapidly than WT alpha-synuclein, the other (A30P) and the corresponding equimolar mixture with WT fibrillized more slowly. However, under conditions that ultimately produced fibrils, the A30P monomer was consumed at a comparable rate or slightly more rapidly than the WT monomer, whereas A53T was consumed even more rapidly. The difference between these trends suggested the existence of nonfibrillar alpha-synuclein oligomers, some of which were separated from fibrillar and monomeric alpha-synuclein by sedimentation followed by gel-filtration chromatography. Spheres (range of heights: 2-6 nm), chains of spheres (protofibrils), and rings resembling circularized protofibrils (height: ca. 4 nm) were distinguished from fibrils (height: ca. 8 nm) by atomic force microscopy. Importantly, drug candidates that inhibit alpha-synuclein fibrillization but do not block its oligomerization could mimic the A30P mutation and thus may accelerate disease progression.


Subject(s)
Nerve Tissue Proteins/chemistry , Parkinson Disease/genetics , Age of Onset , Amino Acid Substitution , Amyloid/chemistry , Benzothiazoles , Chromatography, Gel , Circular Dichroism , Fluorescence , Humans , Microscopy, Atomic Force , Mutation , Nerve Tissue Proteins/genetics , Parkinson Disease/etiology , Parkinson Disease/therapy , Protein Conformation , Synucleins , Thiazoles , Ultracentrifugation , alpha-Synuclein
12.
Plant Cell Physiol ; 40(12): 1253-61, 1999 Dec.
Article in English | MEDLINE | ID: mdl-10682347

ABSTRACT

Arabidopsis thaliana plants were stably transformed with DNA encoding green fluorescent protein and with sequences ensuring retention in the endoplasmic reticulum (ER). Confocal laser scanning microscopy shows fluorescent ER in many cells of seedlings so allowing developmental changes to be documented. The arrangement of the cortical ER changes as cells mature in the hypocotyl and root epidermis. In the root, cells that have completed expansion have reticulate cortical ER resembling the ER described in many previous studies. Expanding cells, however, show extensive perforated sheets of cortical ER which transform quite abruptly into a loose reticulum at the basipetal end of the elongation zone. The reticulum compacts in trichoblasts beginning at sites where root hairs are about to emerge. The compacted form is maintained throughout the hair until growth ceases and the open reticulate form returns. All forms of cortical ER are dynamic and we use a color overlay method to distinguish stable and moving structures in a single composite image. Reticulate ER continuously rearranges its polygonal layout and perforations move and change their shape in the ER sheets of younger cells. ER deeper in the cell (i.e. not close to the plasma membrane) moves more actively so that almost no tubules remain stable even over short periods of less than one minute. The function of the perforated sheets of cortical ER present in growing cells is unknown.


Subject(s)
Arabidopsis/growth & development , Arabidopsis/metabolism , Endoplasmic Reticulum/metabolism , Luminescent Proteins/metabolism , Arabidopsis/genetics , Green Fluorescent Proteins , Luminescent Proteins/genetics , Microscopy, Confocal , Plant Roots/growth & development , Plant Roots/metabolism , Plants, Genetically Modified , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Transformation, Genetic
13.
Science ; 279(5351): 717-20, 1998 Jan 30.
Article in English | MEDLINE | ID: mdl-9445479

ABSTRACT

Cellulose, an abundant, crystalline polysaccharide, is central to plant morphogenesis and to many industries. Chemical and ultrastructural analyses together with map-based cloning indicate that the RSW1 locus of Arabidopsis encodes the catalytic subunit of cellulose synthase. The cloned gene complements the rsw1 mutant whose temperature-sensitive allele is changed in one amino acid. The mutant allele causes a specific reduction in cellulose synthesis, accumulation of noncrystalline beta-1,4-glucan, disassembly of cellulose synthase, and widespread morphological abnormalities. Microfibril crystallization may require proper assembly of the RSW1 gene product into synthase complexes whereas glucan biosynthesis per se does not.


Subject(s)
Arabidopsis Proteins , Arabidopsis/genetics , Arabidopsis/metabolism , Cellulose/biosynthesis , Genes, Plant , Glucosyltransferases/genetics , Amino Acid Sequence , Arabidopsis/enzymology , Cell Membrane/chemistry , Cell Membrane/ultrastructure , Cellulose/chemistry , Cellulose/genetics , Chromosome Mapping , Cloning, Molecular , Crystallization , Freeze Fracturing , Genetic Complementation Test , Glucans/metabolism , Glucosyltransferases/chemistry , Molecular Sequence Data , Mutation , Plant Roots/chemistry , Plant Roots/ultrastructure , Plant Shoots/chemistry
14.
Plant Physiol ; 107(1): 233-243, 1995 Jan.
Article in English | MEDLINE | ID: mdl-12228357

ABSTRACT

To understand the control of spatial patterns of expansion, we have studied root growth in wild type and in the stunted plant 1 mutant, stp1, of Arabidopsis thaliana. We measured profiles of cell length and calculated the distribution of elongation rate. Slow growth of stp1 results both from a failure of dividing cell number to increase and from low elongation rates in the zone of rapid expansion. However, elongation of dividing cells was not greatly affected, and stp1 and wild-type callus grew at identical rates. Thus, rapid cellular expansion differs in mechanism from expansion in dividing cells and is facilitated by the STP1 gene. Additionally, there was no difference between stp1 and wild-type roots for elongation in response to abscisic acid, auxin, ethylene, or gibberellic acid or for radial expansion in response to ethylene; however, stp1 responded to cytokinin much less than wild type. In contrast, both genotypes responded comparably to hormones when explants were cultured; in particular, there was no difference between genotypes in shoot regeneration in response to cytokinin. Thus, effects on root expansion mediated by cytokinin, but not effects mediated by other hormones or effects on other cytokinin-mediated responses, require the STP1 locus.

15.
Cell Biol Int ; 18(11): 1035-47, 1994 Nov.
Article in English | MEDLINE | ID: mdl-7534549

ABSTRACT

A 170 kDa polypeptide that has been partially purified from mung beans is retained by ADP-agarose even in the absence of divalent cations when most non-myosin ATPases and kinases do not bind. Attempts to demonstrate a myosin-like ATPase activity were inconclusive, however, and the protein accounts at most for only a small part of the total K+ EDTA ATPase activity of mung bean extracts. All four monoclonal antibodies raised to the 170 kDa polypeptide react with rabbit skeletal muscle myosin and localize the 170 kDa polypeptide in mung bean root tip cells to the actin-containing phragmoplast and to sites dispersed throughout the cytoplasm which probably include some but not all actin cables. These 4 monoclonals and 3 commercially available antimyosin monoclonals all recognise rabbit skeletal myosin and 160-170 kDa proteins that are present in two other angiosperms tested. In addition, a 158 kDa protein of mung bean reacts with only one antibody and does not bind ADP-agarose. We conclude that strong but not yet conclusive evidence points to the 160-170 kDa proteins of angiosperms being a widely conserved form of myosin heavy chain.


Subject(s)
Adenosine Diphosphate/metabolism , Epitopes/immunology , Fabaceae/chemistry , Myosins/immunology , Plant Proteins/immunology , Plants, Medicinal , Adenosine Triphosphate/metabolism , Animals , Cell Movement , Chromatography, Affinity , Chromatography, Gel , Cross Reactions , Plant Proteins/isolation & purification , Protein Binding , Rabbits , Sepharose
16.
Cell Biol Int ; 18(11): 1019-24, 1994 Nov.
Article in English | MEDLINE | ID: mdl-7894387

ABSTRACT

Antibodies to elongation factor 1 alpha (EF1 alpha), a known 50 kDa actin-bundling protein in Dictyostelium, identified a protein in a whole cell extract of the characean alga Nitella pseudoflabellata that had an apparent molecular weight of 51 kDa. Indirect immunofluorescence microscopy revealed labelling by the EF1 alpha antibodies of the subcortical actin bundles, even after the motile organelles of the endoplasm were removed by perfusion with ATP-containing solutions.


Subject(s)
Actins/metabolism , Eukaryota/metabolism , Peptide Elongation Factors/metabolism , Plant Proteins/metabolism , Amino Acid Sequence , Cytoplasmic Streaming , Eukaryota/ultrastructure , Macromolecular Substances , Microscopy, Fluorescence , Molecular Sequence Data , Organelles/chemistry , Peptide Elongation Factor 1 , Peptide Elongation Factors/analysis , Peptide Elongation Factors/immunology , Plant Proteins/analysis , Plant Proteins/immunology , Sequence Alignment , Sequence Homology, Amino Acid
17.
Plant Cell Physiol ; 35(6): 935-42, 1994 Sep.
Article in English | MEDLINE | ID: mdl-7981964

ABSTRACT

In roots of Arabidopsis thaliana, we examined the effects of low concentrations of microtubule inhibitors on the polarity of growth and on the organization of microtubule arrays. Intact 6 d old seedlings were transplanted onto plates containing inhibitors, and sampled 12 h, 24 h and 48 h later. Oryzalin, a compound that causes microtubule depolymerization, stimulates the radial expansion of roots. The amount of radial swelling is linearly proportional to the logarithm of the oryzalin concentration, from the response threshold, 170 nM, to 1 microM. Cells in the zone of division were slightly more sensitive to oryzalin than were cells in the zone of pure elongation. Radial swelling is also stimulated by taxol, a compound that causes microtubule polymerization. Taxol at 1 microM causes little swelling, but at 10 microM causes extensive radial swelling of cells in the elongation zone, and does not affect cells in the division zone. To examine the microtubules in these roots, we used methacrylate sections with immunofluorescence microscopy. At all concentrations of oryzalin, cortical arrays are disorganized and depleted of microtubules, and the microtubules themselves often appear fragmented. These effects increase in severity with concentration, but are unmistakable at 170 nM. In taxol, cortical arrays appear to be more intensely stained than those of controls. At 10 microM, many cells in growing regions of the stele have longitudinal microtubules, whereas many cells in the cortex appear to have transversely aligned microtubules. Taxol affects microtubules in cells of division and elongation zones to the same extent, despite the observed difference in growth.(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Arabidopsis/drug effects , Dinitrobenzenes/pharmacology , Herbicides/pharmacology , Microtubules/drug effects , Paclitaxel/pharmacology , Sulfanilamides , Arabidopsis/ultrastructure , Microscopy, Fluorescence , Microtubules/ultrastructure
18.
J Neurochem ; 63(2): 413-8, 1994 Aug.
Article in English | MEDLINE | ID: mdl-7913486

ABSTRACT

Developmental changes in the pharmacological properties of the GABAA receptor have been suggested to result from changes in the subunit composition of the receptor complex. The nicotinic acetylcholine receptor is structurally related to the GABAA receptor and undergoes a developmental subunit switch at the neuromuscular synapse. To examine the mechanistic similarities between these systems we sought to find whether the changes in GABAA receptor subunits are controlled by changes in messenger RNA levels, as they are for the nicotinic acetylcholine receptor. We found a 10-fold increase in the level of alpha 1-subunit mRNA, and a small increase in levels of GABAA/benzodiazepine receptors from day 1 to day 24 of rat cerebellar development. We also found that the levels of alpha 1-subunit mRNA were higher than the levels of mRNA encoding other alpha subunits at all developmental time points. The low levels of messenger RNA for alpha 2, alpha 3, and alpha 5 subunits are inconsistent with the high levels of type II benzodiazepine binding in the rat cerebellum at birth because these alpha subunits have been shown to form GABAA receptors with type II benzodiazepine binding. These findings are inconsistent with simple models that would explain the developmental differences in GABAA receptor pharmacology simply as a result of changes in alpha-subunit gene expression.


Subject(s)
Aging/metabolism , Cerebellum/metabolism , Hippocampus/metabolism , RNA, Messenger/metabolism , Receptors, GABA-A/metabolism , Animals , Animals, Newborn , Anti-Anxiety Agents/pharmacology , Binding, Competitive , Cerebellum/growth & development , Flumazenil/metabolism , Hippocampus/growth & development , Kinetics , Macromolecular Substances , Pyridazines/pharmacology , RNA, Messenger/biosynthesis , Rats , Rats, Sprague-Dawley , Receptors, GABA-A/biosynthesis
19.
Planta ; 188(1): 99-105, 1992 Aug.
Article in English | MEDLINE | ID: mdl-24178205

ABSTRACT

We have studied the relationship between pH banding and the organization of cortical microtubules in the alga Chara corallina Klein ex Willd. Microtubules were visualized by immunofluorescence and also by imunogold-silver enhancement to allow immediate comparison of microtubule arrangement with visible structural cell features. In cells that are nearing growth completion, microtubule number and alignment change between acidic and alkaline bands over a distance of a few micrometres. Thus, it appears that the still unknown mechanisms for microtubule organization respond to the localized differences in membrane properties. Band formation was not prevented when microtubules were depolymerized with the herbicide oryzalin, demonstrating that microtubules are not necessary for pH bands to develop in these cells.

20.
J Neurochem ; 54(1): 278-87, 1990 Jan.
Article in English | MEDLINE | ID: mdl-2293617

ABSTRACT

The effect of angiotensin II on the cytosolic free Ca2+ concentration was measured in single mouse neuroblastoma N1E-115 cells loaded with fura-2. Angiotensin II induced a transient concentration-dependent increase in Ca2+ and also increased the production of inositol polyphosphates. The Ca2+ increase did not require extracellular Ca2+ and was unaffected by pretreatment with pertussis toxin. These data suggest that angiotensin II increased Ca2+ by an inositol trisphosphate-mediated release of intracellular Ca2+ following activation of phospholipase C via a pertussis toxin-insensitive guanine nucleotide binding protein. Similar results were obtained with bradykinin. The angiotensin II- or bradykinin-induced increase in Ca2+ occurred after a concentration-dependent latent period. Low concentrations of agonist elicited a small increase in Ca2+ following a variable lag that sometimes exceeded 1 min, whereas at maximally effective angiotensin II concentrations a larger, more rapid increase in Ca2+ occurred without a measurable delay. In some cells, oscillatory increases in Ca2+ were induced by angiotensin II and bradykinin. Possible mechanisms to explain the concentration dependency of the latent period and the oscillatory nature of the increases of Ca2+ are discussed. These results indicate that the mouse neuroblastoma N1E-115 cell represents a useful model for studying the signal response transduction mechanisms regulating the effects of angiotensin II in neuronal cells.


Subject(s)
Angiotensin II/pharmacology , Calcium/metabolism , Tumor Cells, Cultured/metabolism , Animals , Benzofurans , Bradykinin/pharmacology , Cell Differentiation , Cell Division , Cell Line , Cytosol/drug effects , Cytosol/metabolism , Fluorescent Dyes , Fura-2 , Inositol Phosphates/metabolism , Kinetics , Mice , NAD/metabolism , Neuroblastoma , Pertussis Toxin , Tumor Cells, Cultured/cytology , Tumor Cells, Cultured/drug effects , Virulence Factors, Bordetella/pharmacology
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