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At least 307 records · Page 17Linked to original sources
PubMed2004

Divergent potentials for cytoplasmic inheritance within the genus Syringa. A new trait associated with speciogenesis.

Epifluorescence microscopic detection of organelle DNA in the mature generative cell is a rapid method for determining the potential for the mode of cytoplasmic inheritance. We used this method to examine 19 of the known 22 to 27 species in the genus Syringa. Organelle DNA was undetectable in seven species, all in the subgenus Syringa, but was detected in the 12 species examined of the subgenera Syringa and Ligustrina. Therefore, species within the genus Syringa display differences in the potential cytoplasmic inheritance. Closer examination revealed that the mature generative cells of the species in which organelle DNA was detected contained both mitochondria and plastids, but cells of the species lacking detectable organelle DNA contained only mitochondria, and the epifluorescent organelle DNA signals from the mature generative cells corresponded to plastid DNA. In addition, semiquantitative analysis was used to demonstrate that, during pollen development, the amount of mitochondrial DNA decreased greatly in the generative cells of the species examined, but the amount of plastid DNA increased remarkably in the species containing plastids in the generative cell. The results suggest that all Syringa species exhibit potential maternal mitochondrial inheritance, and a number of the species exhibit potential biparental plastid inheritance. The difference between the modes of potential plastid inheritance among the species suggests different phylogenies for the species; it also supports recent conclusions of molecular, systematic studies of the Syringa. In addition, the results provide new evidence for the mechanisms of maternal mitochondrial inheritance in angiosperms.

Cytoplasm↗
PubMed2004

Differential expression of three genes encoding an ethylene receptor in rice during development, and in response to indole-3-acetic acid and silver ions.

Five ethylene receptor genes, OS-ERS1, OS-ERS2, OS-ETR2, OS-ETR3, and OS-ETR4 were isolated and characterized from rice. The genomic structure of OS-ERS1 and OS-ERS2 revealed that the introns within the coding sequences occurred in conserved positions to those of At-ETR1 and At-ERS1, whereas each of the OS-ETR2, OS-ETR3, and OS-ETR4 genes contained 1 intron within its coding region located at a position equivalent to those of At-ERS2, At-ETR2, and At-EIN4. Deduced amino acid sequences of OS-ERS1, OS-ERS2, OS-ETR2, OS-ETR3, and OS-ETR4 showed that they exhibited significant homology to the prokaryotic two-component signal transducer and a wide range of ethylene receptors in a variety of plant species. Northern analysis revealed that the level of OS-ETR2 mRNA was markedly elevated either by the exogenous application of IAA or by ethylene treatment in young etiolated rice seedlings, whereas the OS-ERS1 transcript level was only slightly induced under the same experimental conditions. Pretreatment with silver prevented IAA-induced and ethylene-induced accumulation of both mRNAs (OS-ERS1 and OS-ETR2). However, the abundance of OS-ERS2 mRNA was shown to be down-regulated by both IAA and ethylene treatments, indicating that it was not positively regulated by ethylene. Analysis of the expression of the three ethylene receptor genes in different tissues of rice has unravelled their corresponding tissue-specificity in which OS-ERS1 was constitutively expressed in considerable amounts in all tissues studied, while OS-ERS2 and OS-ETR2 exhibited differential expression patterns in different tissues of rice. Moreover, higher levels of these three mRNAs were commonly observed in anthers when compared with their corresponding levels in other tissues, suggesting the important role played by ethylene involved in the regulation of pollen development in rice. Among the five ethylene receptor genes, the expression levels of both OS-ETR3 and OS-ETR4 were too low to be detected by the northern blot analysis. Results from RT-PCR illustrated that both mRNAs were present in young green rice seedlings and anthers.

Base Sequence↗
PubMed1999

Soluble P-selectin glycoprotein ligand 1 inhibits ocular inflammation in a murine model of allergy.

PURPOSE: To assess the anti-inflammatory modality of a soluble extracellular form of P-selectin glycoprotein ligand 1 (sPSGL-1) in a mouse model of ocular allergic response. METHODS: Potential anti-inflammatory effects of sPSGL-1 were investigated in SWR/J mice sensitized by topical application of short ragweed pollen to the nasal mucosa followed by a challenge of the ocular mucosa with the same allergen. Five experimental groups were included in these studies: A, mice neither sensitized nor challenged with pollen (control group 1); B, animals sensitized but not challenged (control group 2); C, animals not sensitized but challenged (control group 3); D, animals sensitized and challenged; and E, sensitized animals treated with sPSGL-1 before pollen challenge. All experimental groups were evaluated for gross morphologic ocular changes, and histologic assessments were made to determine the onset/progression of inflammatory reactions and to look for evidence of eosinophil infiltration. RESULTS: Mice sensitized and challenged with pollen developed clinical signs consistent with human allergic conjunctivitis. These signs correlate with histologic changes in the conjunctival epithelium and stroma (e.g., edema and extensive eosinophil infiltration). Moreover, the ocular changes also correlated with evidence of eosinophil degranulation. However, sensitized and challenged mice concurrently treated with sPSGL-1 displayed no inflammatory ocular changes associated with a ragweed-induced type-1 hypersensitivity reaction. The lack of ocular changes included the absence of histologic late-phase inflammatory changes of the conjunctiva and a 97% reduction in the induced eosinophil infiltrate. CONCLUSIONS: The antagonistic intervention of cell- cell interactions through the blockade of selectin-dependent leukocyte adhesion may offer novel therapeutic strategies to modulate inflammatory responses. The potent inhibitory effects on eosinophil recruitment and late-phase inflammation suggest a role for sPSGL-1 in the treatment of ocular allergic diseases.

Animals↗
PubMed1993

Developmental regulation of an acyl carrier protein gene promoter in vegetative and reproductive tissues.

The expression of an Arabidopsis acyl carrier protein (ACP) gene promoter has been examined in transgenic tobacco plants by linking it to the reporter gene beta-glucuronidase (GUS). Fluorometric analysis showed that the ACP gene promoter was most active in developing seeds. Expression was also high in roots, but significantly lower in young leaves and downregulated upon their maturation. Etiolated and light-grown seedlings showed the same level of GUS activity, indicating that this promoter is not tightly regulated by light. Histochemical studies revealed that expression was usually highest in apical/meristematic zones of vegetative tissues. Young flowers (ca. 1 cm in length) showed GUS staining in nearly all cell types, however, cell-specific patterns emerged in more mature flowers. The ACP gene promoter was active in the stigma and transmitting tissue of the style, as well as in the tapetum of the anther, developing pollen, and ovules. The results provide evidence that this ACP gene is regulated in a complex manner and is responsive to the array of signals which accompany cell differentiation, and a demand for fatty acids and lipids, during organogenesis.

Acyl Carrier Protein↗
PubMed2001

Morphology of rsw1, a cellulose-deficient mutant of Arabidopsis thaliana.

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.

Arabidopsis↗
PubMed2006

Mitochondrial genome dynamics in plants and animals: convergent gene fusions of a MutS homologue.

Mitochondrial processes influence a broad spectrum of physiological and developmental events in higher eukaryotes, and their aberrant function can lead to several familiar disease phenotypes in mammals. In plants, mitochondrial genes directly influence pollen development and the occurrence of male sterility in natural plant populations. Likewise, in animal systems evidence accumulates to suggest important mitochondrial functions in spermatogenesis and reproduction. Here we present evidence for a convergent gene fusion involving a MutS-homologous gene functioning within the mitochondrion and designated Msh1. In only plants and soft corals, the MutS homologue has fused with a homing endonuclease sequence at the carboxy terminus of the protein. However, the endonuclease domains in the plants and the soft corals are members of different groups. In plants, Msh1 can influence mitochondrial genome organization and male sterility expression. Based on parallels in Msh1 gene structure shared by plants and corals, and their similarities in reproductive behavior, we postulate that this convergent gene fusion might have occurred in response to coincident adaptive pressures on reproduction.

Adenosine Triphosphatases↗
PubMed2006

Sucrose and starch catabolism in the anther of Lilium during its development: a comparative study among the anther wall, locular fluid and microspore/pollen fractions.

In order to better understand the various pathways of sucrose and starch catabolism in the anther of lily (Lilium hybrida var. "Enchantment"), invertase (EC 3.2.1.26) and amylase (EC 3.2.1.1, EC 3.2.1.2) activities were measured separately in different fractions (anther wall, locular fluid and microspore/pollen) and correlated with the sugar content during anther development. Our findings showed significant differences among the fractions analyzed, suggesting that the regulation of sucrose and starch catabolism could follow distinct pathways in each fraction. Glucose and fructose amounts progressively decreased from anther wall to fluid and from fluid to microspore/pollen. Thus, the developing pollen could act as a sink for the carbohydrates that reach the anther. In this sense, cell wall-bound invertases seem to play a major role in soluble sugar partitioning in the different fractions of the anther. Sucrose concentration was found to be substantially higher in the locular fluid than in the other fractions, indicating a probable site for storage. On the other hand, the anther wall tissues could have a buffering function, storing nutrient surplus in starch grains and thus regulating the availability of soluble sugars in the whole anther. All these results proved the advantages of the experimental model proposed here, as well as its usefulness to investigate sugar metabolism in Lilium anthers.

Amylases↗
PubMed2003

Alloplasmic male sterility in Brassica napus (CMS 'Tournefortii-Stiewe') is associated with a special gene arrangement around a novel atp9 gene.

To identify regions of the mitochondrial genome potentially involved in the expression of alloplasmic 'Tournefortii-Stiewe' cytoplasmic male sterility (CMS) in Brassica napus, transcripts of 25 mitochondrial genes were analysed in fertile and near isogenic male-sterile plants (BC(8) generation). Differences were detected in the transcription of genes for subunit 9 of ATP synthase (atp9), cytochrome b (cob) and subunit 2 of NADH dehydrogenase (nad2). Structural analysis of these gene regions revealed differences in genome organisation around atp9 between male-sterile and fertile plants. Three atp9 genes, two of which were hitherto unknown, are present in the mitochondria of CMS plants, and rearrangements upstream of one of these genes have generated a chimeric 193-codon ORF, designated orf193. This region is transcribed as a CMS specific bi-cistronic mRNA of 1.58 kb comprising orf193 and atp9. The level of the aberrant 1.58-kb transcript is reduced in plants restored to fertility by as yet uncharacterized nuclear genes. orf193 encodes a polypeptide of 22.7 kDa which exhibits partial sequence identity to the subunit 6 of the ATP synthase complex. However, as it forms an uninterrupted ORF with one of the newly discovered atp9 genes it may also be translated as a chimeric 30.2-kDa protein. It is likely that either or both gene products interfere with the function or assembly of the mitochondrial F(0)F(1)-ATP synthase, thus impairing the highly ATP-dependent process of pollen development. The novel molecular features of alloplasmic 'Tournefortii-Stiewe' CMS are discussed with respect to the other known mechanisms of CMS in B. napus.

Apoproteins↗
PubMed2000

Interaction of PRK1 receptor-like kinase with a putative elF2B beta-subunit in tobacco.

PRK1, a receptor-like kinase that is expressed in pollen, pollen tubes, and ovaries, has been shown to play important roles in pollen development and embryo sac development in Petunia inflata. We have used the kinase domain of PRK1 as a bait in the yeast two-hybrid system to identify PRK1-interacting proteins. The screening resulted in isolation of a cDNA encoding a protein highly homologous to the human and yeast beta-subunit of translation initiation factor 2B (eIF2B-beta), which was designated NeIF2Bbeta. eIF2B is a guanine nucleotide exchange protein that functions in the regulation of translation in eukaryotic cells. Deletion mutants of NeIF2Bbeta were analyzed for their interaction with PRK1, and the results suggested that the N-terminal half of NeIF2Bbeta, especially the region between residue 103 and 235, is important for the interaction. This protein association was confirmed by in vitro binding assay of the recombinant NeIF2Bbeta and PRK1 proteins. Despite high sequence homology between NeIF2Bbeta and its yeast counterpart, the NeIF2Bbeta cDNA could not rescue the phenotype of the yeast mutant strain lacking the GCD7 gene encoding eIF2B-beta, when transferred into the mutant strain.

Amino Acid Sequence↗
PubMed1987

Effects of chemical smokes on flora and fauna under field and laboratory exposures.

Various types of obscurant smokes are used routinely in training by the U.S. Army. Because continued routine use of the smokes could be detrimental to the native flora and fauna at training sites, a preliminary biological and chemical field study of fogoil, hexachloroethane, and tank diesel smokes was conducted. Smoke plumes were sampled and chemically analyzed at distances of 15-150 m from the smoke source where Tradescantia clones 4430 and 03 and the native plant Ambrosia dumosa and the native rodent Dipodomys merriami were exposed for 30 min. In addition, Tradescantia clone 4430 was exposed to tank diesel in the laboratory at concentration levels equivalent to exposure at 15 and 50 m. Tradescantia clones were examined for mutagenic effects indicated by micronuclei induction in developing pollen and pink somatic mutations in stamen hairs. Photosynthetic perturbations were measured in Tradescantia and A. dumosa using variable fluorescence induction. Animals were examined for sister chromatid exchanges and chromosome aberrations. It was found that all of the smokes tested exerted varying degrees of physiological and mutagenic effects in one or more assay system at one or more exposure distance. The studies reported here indicate that exposed ecological systems, or at least components of these systems, are at a higher risk than are unexposed components (e.g., organisms) for several types of damage attributed to obscurant smoke exposure.

Animals↗
PubMed2004

Identification and characterization of a UDP-D-glucuronate 4-epimerase in Arabidopsis.

One of the major sugars present in the plant cell wall is d-galacturonate, the dominant monosaccharide in pectic polysaccharides. Previous work indicated that one of the activated precursors necessary for the synthesis of pectins is UDP-d-galacturonate, which is synthesized from UDP-d-glucuronate by a UDP-d-glucuronate 4-epimerase (GAE). Here, we report the identification, cloning and characterization of a GAE6 from Arabidopsis thaliana. Functional analysis revealed that this enzyme converts UDP-d-glucuronate to UDP-d-galacturonate in vitro. An expression analysis of this epimerase and its five homologs in the Arabidopsis genome by quantitative RT-PCR and promoter::GUS fusions indicated differential expression of the family members in plant tissues and expression of all isoforms in the developing pollen of A. thaliana.

Arabidopsis↗
PubMed2005

Temporal and transient expression of olive enoyl-ACP reductase gene during flower and fruit development.

Enoyl-ACP reductase is a catalytic component of the fatty acid synthetase (FAS) type II system in plants that is involved in the de novo fatty acid biosynthesis in plastids. A cDNA encoding an enoyl-ACP reductase responsible for the removal of the trans-unsaturated double bonds to form saturated acyl-ACP has been isolated from a library made from ripening fruits of Olea europaea L. The predicted protein contains 393 amino acid residues including a consensus chloroplast specific transit peptide. A strong homology was observed when olive enoyl-ACP reductase aligned with other plant sequences. Southern hybridization analysis revealed that enoyl-ACP reductase is encoded by a single gene in olives. Northern hybridization showed a transient expression of the enoyl-ACP reductase (ENR) gene at early stages of drupe (5-7 weeks after flowering, WAF), embryo and endosperm (13-16 WAF) while in mesocarp (13-19 WAF) the expression remained at high levels. In situ hybridization showed particularly prominent expression in the palisade and vascular tissue of young leaves, the tapetum, developing pollen grains and vascular tissue of anthers and to less extent in the embryo sac and transmitting tissue of the carpel. The distinctive spatial and temporal regulation of the ENR gene is consistent with major roles, not only in thylakoid membrane formation and fatty acid deposition, but also in the provision of precursor molecules for the biosynthesis of oxilipins that are important in plant tissues involved in transportation and reproduction.

Amino Acid Sequence↗
PubMed2000

Isolation of a Brassica napus L. cDNA encoding a putative high-mobility-group HMG I/Y protein.

A cDNA encoding a high-mobility-group protein has been isolated from a microspore-specific library of Brassica napus. The 930 bp cDNA contains a 612 bp open reading frame encoding a protein of 203 amino acids residues exhibiting significant homology to HMG-I/Y protein from Arabidopsis thaliana (62%). The predicted protein contains four copies of the 'AT-hook' motif which is involved in binding A/T-rich DNA. Southern blotting indicates that the HMG-I/Y gene is a single-copy gene in B. napus. Transcription of the HMG-I/Y gene was detected in all tissues examined, with the highest expression in pollen-derived embryos. In situ localization studies of flower organs indicate the transcript to be preferentially located in petals and sepals. Subcellular localization analysis performed during pollen development showed that the transcript of the HMG-I/Y gene is predominantly associated with polysomes.

Journal Article↗
PubMed2003

Induced abnormality in Mir- and Earth grown Super Dwarf wheat.

Super-dwarf wheat grown on the Mir space station using the Svet "Greenhouse" exhibited morphological, metabolic and reproductive abnormalities compared with Earth-grown wheat. Of prominent importance were the abnormalities associated with reproductive ontogeny and the total absence of seed formation on Mir. Changes in the apical meristem associated with transition from the vegetative phase to floral initiation and development of the reproductive spike were all typical of 'Super-Dwarf' wheat up to the point of anthesis. Observation of ruptured anthers from the Mir-grown plants revealed what appeared to be normally developed pollen. These pollen gains, however, contained only one nuclei, while normal viable pollen is tri-nucleate. A potentially important difference in the flight experiment, compared with ground reference studies, was the presence of a high level of atmospheric ethylene (1,200 ppb). Ground studies conducted by exposing 'Super-Dwarf' wheat to ethylene just prior to anthesis resulted in manifestation of the same abnormalities observed in the space flight samples.

Environment, Controlled↗
PubMed2003

Organ-specific expressions and chromosomal locations of two mitochondrial aldehyde dehydrogenase genes from rice (Oryza sativa L.), ALDH2a and ALDH2b.

Recent studies have suggested that mitochondrial aldehyde dehydrogenase (aldehyde:NAD(P)(+) oxidoreductase, EC 1.2.1.3) (ALDH2) plays essential roles in pollen development in plants. Rice (Oryza sativa L.) ALDH2 is encoded by at least two ALDH2 genes, one of which (ALDH2a) was previously identified. In this study, to understand the roles of ALDH2 in rice, we isolated and characterized a cDNA clone encoding another rice ALDH2 (ALDH2b). An in vitro ALDH assay indicated that ALDH2b possesses an NAD(+)-linked activity for oxidation of acetaldehyde, glycolaldehyde and propionaldehyde. Northern blot and immunoblot analyses revealed that ALDH2b was constitutively present in all the organs examined, whereas ALDH2a was expressed in leaves of dark-grown seedlings and panicles. By RFLP linkage mapping, the ALDH2a and ALDH2b genes were mapped to the long arm of chromosome 2 and the short arm of chromosome 6, respectively. We suggest that the rice ALDH2a and ALDH2b genes are orthologues of maize mitochondrial ALDH genes, rf2b and rf2a, respectively.

Aldehyde Dehydrogenase↗
PubMed2003

Endonuclease genes up-regulated in tissues undergoing programmed cell death are expressed during male gametogenesis in barley.

In the process of programmed cell death (PCD), a key role has been attributed to endonucleases capable to cleave nuclear DNA at internucleosomal sites. In barley (Hordeum vulgare L.), two such nucleases (Bnuc1 and BEN1) were individually identified in unrelated tissues. In the present work, we demonstrate that their genes are also expressed in immature anthers at different stages of pollen development. Further experiments carried out on RNA extracted from immature barley anthers led to discover a novel endonuclease gene, namely Bnuc2 (AJ311603 in the EMBL/GenBank/DDBJ databases), eventually found up-regulated at the tetrad stage. The protein encoded was found to conserve large sequence portions of Bnuc1 and BEN1 endonucleases, including the domain regions involved in secretion and DNA/RNA binding. A survey conducted on barley EST libraries showed that Bnuc2 and BEN1 mRNAs are jointly present also in the transcriptome of 20 DAP spike and that other endonuclease ESTs are co-expressed with Bnuc1 or BEN1 in tissues where PCD has been recorded. Therefore, it can be concluded that during the PCD process, a set of S1-type endonucleases is synthesised regardless of the tissue considered.

Amino Acid Sequence↗
PubMed2003

Of plants and other pets: practical aspects of freeze-substitution and resin embedding.

Representative tissues from higher plants (e.g. developing pollen, somatic anther tissues from the monocotyledonous angiosperm Ledebouria) and mammalian cell cultures were successfully cryoimmobilized by means of high-pressure freezing. Various substitution and embedding protocols were then evaluated considering the preservation of ultrastructural details, membrane staining, immunolabelling properties, as well as reproducibility and ease of use. Two types of recipe proved to be highly suitable for most applications, regardless of type, developmental stage or physiological conditions of the cells: (i) the best choice for morphology is still osmium in acetone (optionally supplemented with uranyl acetate) followed by embedding in Epon and/or Araldite; (ii) feasible approaches for immunocytochemistry are freeze-substitution with ethanol containing uranyl acetate and formaldehyde, or with pure acetone (in the case of fixation-sensitive antigens), followed by embedding with LR-white acrylic resin; though being far from optimal, these combinations represent, in my opinion, an acceptable compromise between labelling intensity, section stability, structural preservation and health hazards. Notably, the patterns observed in Ledebouria were consistent with data obtained from a broad range of other specimens from all kingdoms (e.g. leaves and callus cultures from angiosperms, gymnosperm roots with their ectomycorrhizal fungi, mammalian cell cultures and eubacteria). Finally, a warning is given as to the extractive potentials of embedding resins (Spurr's mixture, LR-white, but also Epon) being sometimes the cause of unacceptable artefacts, both in plant and in mammalian cells prepared by cryoimmobilization and freeze-substitution.

Animals↗
PubMed1995

Developmental regulation of ribosomal protein L16 genes in Arabidopsis thaliana.

Lateral roots can be synchronously induced in Arabidopsis by a brief auxin treatment. An early event in the development of a lateral root primordium is the accumulation of mRNAs encoding ribosomal proteins. In situ hybridizations show that mRNA encoding one ribosomal protein, L16, accumulates in all rapidly proliferating tissues including the shoot and root apical meristems and lateral root primordia. To understand further the mechanisms by which ribosomal proteins are coordinately synthesized, two genes encoding the ribosomal protein L16 were isolated from Arabidopsis thaliana. Promoter sequences from each RPL16A and RPL16B were fused to the beta-glucuronidase reporter gene GUS. The promoter of RPL16B(from -848 to -19) conferred X-Gluc staining in proliferating tissues including the shoot and root apical meristems. When GUS was expressed from the RPL16A promoter (from -875 to -22), X-Gluc staining was observed in cells in the root stele and in anthers. When seedlings transformed with either promoter construct were treated with auxin to induce lateral roots, X-Gluc staining accumulated in the lateral root primordia by 16 h after induction. Transcription of the RPL16B promoter appears to be correlated with cell division, while transcription of the RPL16A promoter is very cell specific. Expression of two genes encoding L16 during the early phase of lateral root initiation and in developing pollen may serve to increase levels of ribosomal proteins during the rapid growth of these tissues.

Amino Acid Sequence↗