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At least 1,621 records · Page 90Linked to original sources
PubMed1996

Transgenic male-sterile plant induced by an unedited atp9 gene is restored to fertility by inhibiting its expression with antisense RNA.

We have previously shown that the expression of an unedited atp9 chimeric gene correlated with male-sterile phenotype in transgenic tobacco plant. To study the relationship between the expression of chimeric gene and the male-sterile trait, hemizygous and homozygous transgenic tobacco lines expressing the antisense atp9 RNA were constructed. The antisense producing plants were crossed with a homozygous male-sterile line, and the F1 progeny was analyzed. The offspring from crosses between homozygous lines produced only male-fertile plants, suggesting that the expression antisense atp9 RNA abolishes the effect of the unedited chimeric gene. In fact, the plants restored to male fertility showed a dramatic reduction of the unedited atp9 transcript levels, resulting in normal flower development and seed production. These results support our previous observation that the expression of unedited atp9 gene can induce male sterility.

Base Sequence↗
PubMed1982

Assembly of storage protein oligomers in the endoplasmic reticulum and processing of the polypeptides in the protein bodies of developing pea cotyledons.

Cotyledons of developing pea seeds (pisum sativum L.) were labeled with radioactive amino acids and glucosamine, and extracts were prepared and separated into fractions rich in endoplasmic reticulum (ER) or protein bodies, The time-course of synthesis of the polypeptides of legumin and vicilin and the site of their assembly into protein oligomers were studied using immunoaffinity gels and sucrose density gradients. When cotyledons were pulse-labeled (1-2 h), newly synthesized vicilin was present as a series of polypeptides with M(r) 60,000-65,000, and newly synthesized vicilin was present as series of polypeptides with M(r) 75,000, 70,000, 50,000, and 49,000. These radioactive polypeptides were found primarily in the ER (Chrispeels et al., 1982, J Cell Biol., 93:5- 14). During a subsequent chase period, newly synthesized reserve proteins were initially present in the protein bodies in the above-named polypeptides. Between 1 and 20 h later, radioactive legumin subunits (M(r) 40,000 and 19,000) and smaller vicilin polypeptides (M(r) 34,000, 30,000, 25,000, 18,000, 14,000, 13,000, and 12,000) appeared in the protein bodies. The appearance of these labeled polypeptides in the protein bodies was not the result of a slow transport from the ER (or cytoplasm). Newly synthesized legumin and vicilin polypeptides were assembled into oligomers of 8S and 7S, respectively, in the ER. They appeared in the protein bodies in these oligomeric forms before the appearance of the smaller polypeptides (M(r) less than 49,000). These results indicate that the smaller vicilin polypeptides (M(r) less than 49,000) arise delayed posttranslational processing of some or all of the larger vicilin polypeptides. The precursors of legumin are completely processed in the protein bodies 2-3 h after their synthesis. The processing of the vicilin precursors is much slower (6-20 h) and only a fraction of the precursor molecules are processed. As a result both large (M(r) more than 49,000) and small polypeptides of vicilin accumulate in the protein bodies, whereas legumin accumulates only as polypeptides of M(r) 40,000 and 19,000.

Endoplasmic Reticulum↗
PubMed2004

Molecular characterization and expression studies during melon fruit development and ripening of L-galactono-1,4-lactone dehydrogenase.

The last step of ascorbic acid (AA) biosynthesis is catalysed by the enzyme L-galactono-1,4-lactone dehydrogenase (GalLDH, EC 1.3.2.3), located on the inner mitochondrial membrane. The enzyme converts L-galactono-1,4-lactone to ascorbic acid (AA). In this work, the cloning and characterization of a GalLDH full-length cDNA from melon (Cucumis melo L.) are described. Melon genomic DNA Southern analysis indicated that CmGalLDH was encoded by a single gene. CmGalLDH mRNA accumulation was detected in all tissues studied, but differentially expressed during fruit development and seed germination. It is hypothesized that induction of CmGalLDH gene expression in ripening melon fruit contributes to parallel increases in the AA content and so playing a role in the oxidative ripening process. Higher CmGalLDH message abundance in light-grown seedlings compared with those raised in the dark suggests that CmGalLDH expression is regulated by light. Finally, various stresses and growth regulators resulted in no significant change in steady state levels of CmGalLDH mRNA in 20-d-old melon seedlings. To the authors' knowledge, this is the first report of GalLDH transcript induction in seed germination and differential gene expression during fruit ripening.

Amino Acid Sequence↗
PubMed1983

The vicilin gene family of pea (Pisum sativum L.): a complete cDNA coding sequence for preprovicilin.

A cDNA plasmid bank has been constructed using mRNA from developing pea seeds and three cDNAs coding for vicilin polypeptides have been selected. These cDNAs have been sequenced and between them cover the whole of the coding sequence plus part of the 5' and 3' untranslated regions. Comparison with amino acid sequence data from the protein indicates that vicilin is synthesised as preprovicilin with subsequent removal of a signal peptide and a C-terminal peptide as well as post translational endo-proteolytic cleavage. The cDNAs represent two different classes of vicilin genes whilst amino acid data show that there are at least three major classes of vicilin polypeptide. The vicilin sequences show extensive homology with conglycinin and phaseolin except in the regions of the internal proteolytic cleavages. The evolutionary significance of this relationship is discussed.

Amino Acid Sequence↗
PubMed1985

Sequence of a pseudogene in the legumin gene family of pea (Pisum sativum L.).

A second legumin gene, denoted psi Leg D, has been located on the pea genomic clone lambda Leg 1, approx. 1.3 Kbases 3' of Leg A, in the same orientation. The complete sequence of psi Leg D shows that it is a pseudogene, having two stop codons near the 5' end of its predicted coding sequence, as well as deletions and frame shift errors when compared to Leg A. No transcripts from this gene could be detected in developing pea seeds. Leg A and psi Leg D are homologous over their coding sequences, and partially homologous in the intron sequences and the immediate 5' flanking sequences. Other flanking sequences of the two genes show no significant homology, apart from the presence of polyadenylation signals 3' to both coding sequences. The introns in the two genes occur in corresponding positions in the sequences, but a deletion in psi Leg D affects the 3' boundary of IVS-2. Hybridisation of psi Leg D to pea genomic DNA suggests that it does not represent a hitherto undetected sub-family of legumin genes.

Amino Acid Sequence↗
PubMed2000

Gibberellin biosynthesis: its regulation by endogenous and environmental signals.

The hormone gibberellin (GA) plays an essential role in many aspects of plant growth and development, such as seed germination, stem elongation and flower development. In recent years, exciting progress has been made in understanding how the biosynthesis of this hormone is regulated by endogenous and environmental factors. This has resulted from isolation of genes encoding enzymes involved in GA biosynthesis and metabolism, which also enabled us to manipulate the pathway by modifying the expression of these genes in transgenic plants. In addition, new GA response mutants provided information about how signaling components are involved in feedback regulation of the GA biosynthetic pathway.

Environment↗
PubMed2004

The maize O2 and PBF proteins act additively to promote transcription from storage protein gene promoters in rice endosperm cells.

A transient expression assay system was employed to investigate the possible use of the maize Opaque 2 (O2) and prolamin box binding factor (PBF) proteins as transcriptional activators of rice and wheat storage protein gene promoters. When assayed in developing rice endosperm cells, either O2 or PBF alone could increase transcription from the promoter of the rice glutelin gene, Gt1. However, mutant forms of O2 and PBF that are defective in DNA binding could not. Co-transfection with both transcriptional activators resulted in an additive increase in transactivation of the Gt1 promoter. Co-bombardment of a Gt1::GUS construct with plasmids expressing the DNA binding domains of O2 and PBF in antisense orientation resulted in a decrease of GUS expression below background levels. Similar stimulatory and additive effects of O2 and PBF could be observed on the promoters from other storage protein genes including rice globulin (Glb), prolamins (RP6 and PG5a) and a wheat glutenin (Bx7). However, responsiveness of the promoters from non-storage protein genes like rice actin and CaMV 35S to O2 and PBF was insignificant. Our results indicate that the maize O2 and PBF proteins can act singly or additively as effective stimulators of heterologous storage protein promoters in developing rice endosperm cells. These data support the use of well-characterized transcription factors from maize as an effective means of increasing the expression level of recombinant proteins in developing rice seeds.

Antisense Elements (Genetics)↗
PubMedDate not supplied

Nurturing the seeds of learning: a professional development initiative for hospital-based nurse educators.

This article describes a collaborative initiative between two healthcare organizations to promote professional development of nurse educators from hospitals in neighboring regions. Information collected from a needs survey and a preregistration questionnaire was used to develop didactic and interactive sessions of a 1-day conference. Several brainstorming sessions were utilized to engage participants and to facilitate networking. Participants responded positively to this professional development conference in meeting their learning needs.

Canada↗
PubMed2005

The AIP2 E3 ligase acts as a novel negative regulator of ABA signaling by promoting ABI3 degradation.

The phytohormone abscisic acid (ABA) mediates many complex aspects of plant development including seed maturation, dormancy, and germination as well as root growth. The B3-domain transcription factor abscisic acid-insensitive 3 (ABI3) is a central regulator in ABA signaling, but little is known of how this factor is regulated. Here, we show that ABI3 is an unstable protein and that an ABI3-interacting protein (AIP2), which contains a RING motif, can polyubiquitinate ABI3 in vitro. The AIP2 E3 ligase activity is abolished by mutations (C230S; C231S) in the RING motif and the AIP2 (C/S) mutant functions in a dominant-negative manner. AIP2 has a stronger binding affinity for the B2 + B3 domain of ABI3 than the A1 + B1 domain, but only ubiquitinates the latter. In double-transgenic plants, induced AIP2 expression leads to a decrease in ABI3 protein levels. In contrast, ABI3 levels are elevated upon induced expression of the AIP2 RING mutant, which interferes with the endogenous AIP2 E3 activity. An aip2-1-null mutant shows higher ABI3 protein levels compared with wild type after seed stratification, and is hypersensitive to ABA, mimicking the ABI3-overexpression phenotype, whereas AIP2-overexpression plants contain lower levels of ABI3 protein than wild type and are more resistant to ABA, phenocopying abi3. Our results indicate that AIP2 negatively regulates ABA signaling by targeting ABI3 for post-translational destruction.

Abscisic Acid↗
PubMed1993

Expression of an Endopeptidase (EP-C1) in Phaseolus vulgaris Plants.

Endopeptidase activity increases continually in pods of maturing fruits of French bean (Phaseolus vulgaris L. cv Goldstar) plants and is thought to participate in the protein mobilization in pods during the development of seeds (M. Endo, T. Minamikawa, D. Yamauchi, W. Mitsuhashi [1987] J Exp Bot 38: 1988-1995). In the present studies, one of the major endopeptidase forms, designated EP-C1, was purified as a 34-kD polypeptide from pods of maturing French bean fruits. EP-C1 was found to be immunologically distinguished from other forms in extracts from pods, but homologous to SH-EP, the major cysteine endopeptidase expressed in cotyledons of germinating Vigna mungo seeds (W. Mitsuhashi, T. Minamikawa [1989] Plant Physiol 89: 274-279). The level of endopeptidase that reacted with the antiserum to EP-C1 increased in pods as the fruit maturation proceeded. EP-C1 was also immunologically detected in stems of French bean plants bearing fruits of later maturation stages. Protein immunoblotting showed that a 34-kD polypeptide corresponding to EP-C1 in molecular mass occurred in extracts from 7- to 9-d cotyledons of germinating French bean seeds. In addition, two other polypeptides with slightly higher molecular masses were observed in extracts from 3- to 5-d cotyledons. We suggest that these two polypeptides are intermediates involved in posttranslational processing of EP-C1. RNA blot hybridization with EP-C1 cDNA as a probe showed that EP-C1 mRNA occurred in pods of fruits at later maturing stages and also in cotyledons of 3- to 7-d germinating seeds.

Journal Article↗
PubMed1993

Expression and Localization of Plant Protein Disulfide Isomerase.

A cDNA clone encoding a putative protein disulfide isomerase (PDI, EC 5.3.4.1) from alfalfa (Medicago sativa L.) was expressed in Escherichia coli cells, and an antiserum was raised against the expressed PDI-active protein. The antiserum recognized a protein of approximately 60 kD in extracts from alfalfa, soybean, and tobacco roots and stems. Levels of this protein remained relatively constant on exposure of alfalfa cell suspension cultures to the protein glycosylation inhibitor tunicamycin, whereas a slightly lower molecular mass form, also detected by the antiserum, was induced by this treatment. A lower molecular mass form of PDI was also observed in roots of alfalfa seedlings during the first 5 weeks after germination. PDI levels increased in developing soybean seeds up to 17 d after fertilization and then declined. Tissue print immunoblots revealed highest levels of PDI protein in the cambial tissues of soybean stems and petioles and in epidermal, subepidermal, cortical, and pith tissues of stems of alfalfa and tobacco. Immunogold electron microscopy confirmed the localization of PDI to the endoplasmic reticulum in soybean root nodules.

Journal Article↗
PubMed1999

Accumulation of soybean glycinin and its assembly with the glutelins in rice

Saline-soluble glycinins and insoluble glutelins are the major storage proteins in soybean (Glycine max) and rice (Oryza sativa), respectively. In spite of their differences in solubility properties, both proteins are members of the 11S globulin gene family based on their similarities in primary sequences and processing of the coded protein. Wild-type and methionine-modified glycinin coding sequences were expressed in transgenic rice plants under the control of the rice glutelin GluB-1 promoter. Glycinins were specifically synthesized in the endosperm tissue and co-localized with glutelins in type II protein bodies. They assembled into 7S and 11S species, similar to what was observed in developing soybean seeds. This pattern was quite different from that displayed by the rice glutelins in untransformed plants, in which processed subunits sedimenting at 2S were apparent. In glycinin-expressing transgenic plants, however, glutelins were observed sedimenting at 7S and 11S with lesser amounts in the 2S region. A portion of the glycinins was also found associated in the insoluble glutelin fraction. Renaturation experiments suggested that the hybrid glycinin-glutelin oligomers were formed through specific interactions. Overall, these results indicate that despite significant differences in the assembly of soybean glycinin and rice glutelin, both proteins can assemble with each other to form soluble hexameric oligomers or insoluble aggregates.

Journal Article↗
PubMed1999

Hydrophobic protein synthesized in the pod endocarp adheres to the seed surface.

Soybean (Glycine max [L.] Merr.) hydrophobic protein (HPS) is an abundant seed constituent and a potentially hazardous allergen that causes asthma in persons allergic to soybean dust. By analyzing surface extracts of soybean seeds with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino-terminal microsequencing, we determined that large amounts of HPS are deposited on the seed surface. The quantity of HPS present varies among soybean cultivars and is more prevalent on dull-seeded phenotypes. We have also isolated cDNA clones encoding HPS and determined that the preprotein is translated with a membrane-spanning signal sequence and a short hydrophilic domain. Southern analysis indicated that multiple copies of the HPS gene are present in the soybean genome, and that the HPS gene structure is polymorphic among cultivars that differ in seed coat luster. The pattern of HPS gene expression, determined by in situ hybridization and RNA analysis, shows that HPS is synthesized in the endocarp of the inner ovary wall and is deposited on the seed surface during development. This study demonstrates that a seed dust allergen is associated with the seed luster phenotype in soybean and that compositional properties of the seed surface may be altered by manipulating gene expression in the ovary wall.

Allergens↗
PubMed2000

Trivalent ions activate abscisic acid-inducible promoters through an ABI1-dependent pathway in rice protoplasts.

The plant hormone abscisic acid (ABA) mediates many vital processes in plant growth and development, including seed dormancy, cell division, water use efficiency, and adaptation to drought, salinity, chilling, pathogen attack, and UV light. Our understanding of ABA signal transduction is fragmentary and would benefit from specific and facile probes of the process. Protoplasts from rice (Oryza sativa L. cv IR54) embryonic suspension cultures cotransformed with effector plasmids encoding the maize (Zea mays) VIVIPAROUS1 cDNA and/or the Arabidopsis dominant negative mutant (abi1-1) ABA-insensitive cDNA demonstrated genetic interactions of VIVIPAROUS1 and abi1-1 in transactivation of the ABA-inducible HVA1 promoter from barley (Hordeum vulgare), suggesting the mechanisms of these effectors are conserved among monocots and dicots. Trivalent ions have been shown to act as an effector of gene expression in plants and animals, although the mechanism of action is unknown. We show in two complementary transient ABA-inducible gene expression assays (beta-glucuronidase and luciferase enzymatic activities and quantitative flow cytometry of green fluorescent protein) that trivalent ions specifically interact with an ABI1-dependent ABA-signaling pathway leading to gene expression. Trivalent ions mimic ABA effects on gene expression and may be a useful tool to study ABA signaling.

Abscisic Acid↗
PubMed1968

Phosphorylases I and II of Maize Endosperm.

Two phosphorylases have been found in the endosperm of Zea mays. Phosphorylase I is found through all stages of endosperm development and seed germination investigated. The other enzyme, phosphorylase II appears only at the stage of rapid starch biosynthesis and is not found during germination. At 22 days after pollination, the activity of phosphorylase II is 10 times that of phosphorylase I. These 2 phosphorylases are separable by column chromatography and behave differently in several respects.Phosphorylase I cannot utilize maltose as a primer while phosphorylase II does so readily. Furthermore, phosphorylase II can synthesize an amylose-like polymer from a "primer free" system after a lag phase.Phosphorylase II is inhibited severely at pH 5.8 by ATP, GTP, ADP, and GDP, and less drastically by UTP, CTP, UDP and CDP. Phosphorylase I is somewhat inhibited by purine nucleotides but not by pyrimidine nucleotides. In all cases, the inhibition is pH-dependent. Phosphorylase I is inhibited competitively by ATP while phosphorylase II is inhibited non-competitively.Phosphorylase II is markedly stimulated by 10 mm Mg(2+) and by 2 mm ethylenediamine tetraacetic acid while phosphorylase I is relatively little affected.

Journal Article↗
PubMed1971

Distribution and Variation of Indole Glucosinolates in Woad (Isatis tinctoria L.).

The exceptionally high levels in woad (Isatis tinctoria L.) of three indolic goitrogens, namely glucobrassicin, neoglucobrassicin, and glucobrassicin-1-sulfonate, permit the facile study of their distribution in the plant and their changes during its development. Woad seeds contain as much as 0.23% fresh weight of glucobrassicin but no other indole glucosinolate, while 1-week-old seedlings also contain substantial amounts of neoglucobrassicin and glucobrassicin-1-sulfonate in their shoots whether grown in the light or dark. The sulfonate is not found in roots, and light depresses neoglucobrassicin levels in shoots. Sterile root cultures synthesize glucobrassicin and neoglucobrassicin, and significant quantities of these were even found to be excreted by the roots of intact sterile seedlings in culture. This may explain the long known deleterious effect of woad and other cruciferous crops on subsequent plantings and the observation could be of ecological importance. Long term changes in levels of all three substances in the plant are similar and are compatible with earlier suggestions that the compounds could be auxin precursors at the time of flower stem elongation. Since sterile seedlings readily incorporate (35)SO(4) (2-) into indole glucosinolates and relative specific radioactivities suggest that glucobrassicin is the precursor of the other two compounds, pathways of goitrogen biosynthesis should be relatively easily determined in this material.

Journal Article↗
PubMed1982

Wheat Storage Proteins : ISOLATION AND CHARACTERIZATION OF THE GLIADIN MESSENGER RNAs.

A total RNA extract was prepared from developing wheat seeds using guanidine-HCl to eliminate endogenous RNase activity. The RNA preparation, substantially free of protein, carbohydrate and DNA, was chromatographed on either a poly uridylic acid-agarose or poly guanylic acid-agarose column to yield a gliadin-enriched mRNA fraction. Only slight differences were observed for the products synthesized in a wheat germ cell-free translation system when either poly adenylic acid-enriched or cytosine-rich RNA was used as a template. These results are consistent with the high proline content of the gliadins and indicate that a large proportion of the mRNA activity in these RNA preparations is directed toward gliadin synthesis. After a second affinity chromatography step, the gliadin-enriched mRNA fraction was fractionated by two cycles on sucrose-density gradient centrifugation under denaturing conditions. The RNA sedimented as a broad band with a peak at 14S and a shoulder at the 11S region of the sucrose gradient. RNA from the peak 14S fraction translated predominantly the two major gliadin polypeptides which had molecular weights of 34,000 and 36,000. Analysis of the 14S RNA by methylmercury hydroxide-agarose gel electrophoresis revealed the presence of a predominant RNA species with a molecular size of 415,000 (1,200 nucleotides).

Journal Article↗