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PubMed2003

A plant genetically modified that accumulates Pb is especially promising for phytoremediation.

From a number of wild plant species growing on soils highly contaminated by heavy metals in Eastern Spain, Nicotiana glauca R. Graham (shrub tobacco) was selected for biotechnological modification, because it showed the most appropriate properties for phytoremediation. This plant has a wide geographic distribution, is fast-growing with a high biomass, and is repulsive to herbivores. Following Agrobacterium mediated transformation, the induction and overexpression of a wheat gene encoding phytochelatin synthase (TaPCS1) in this particular plant greatly increased its tolerance to metals such as Pb and Cd, developing seedling roots 160% longer than wild type plants. In addition, seedlings of transformed plants grown in mining soils containing high levels of Pb (1572 ppm) accumulated double concentration of this heavy metal than wild type. These results indicate that the transformed N. glauca represents a highly promising new tool for use in phytoremediation efforts.

Biodegradation, Environmental↗
PubMed1999

An evaluation of plaster of Paris barriers used under various materials to repair furcation perforations (in vitro study).

The present study was undertaken to evaluate the effect of plaster of Paris barriers on the sealing ability of various materials when used to repair furcation perforations. The study was conducted on 90 human permanent molars with well developed, nonfused roots. Access openings and furcation perforations were prepared in the pulp chamber floor. The teeth were divided into one control and five experimental groups of 15 teeth each. In the experimental group, plaster of Paris barriers were created in the perforations and then sealed with silver amalgam, glass ionomer (GI), self-cured composite resin, IRM, or AH26. Access openings were filled with composite resin. The teeth were submerged in a solution of 2% methylene blue dye for 2 wk. Finally, the samples were sectioned and evaluated for linear dye leakage and analyzed statistically. Maximum dye penetration was observed in amalgam followed in a decreasing order by GI, composite, IRM, and AH26. AH26 showed the best sealing ability in the presence of plaster of Paris barriers followed by IRM, composite resin, and GI. Amalgam showed the poorest sealing ability when used to repair furcation perforations.

Analysis of Variance↗
PubMed2001

Influence of the embryonal-suspensor mass (ESM) sampling on development and proliferation of maritime pine somatic embryos.

Two maturation media with high and low concentration of gellan gum were used to evaluate the maturation performances of four maritime pine ESM (embryonal-suspensor mass) lines. The maturation performance is influenced by sampling modalities; the outer part of the ESM yielded more cotyledonary embryos than the inner part or the whole colony. ESM lines showing several stage 1 embryos at the periphery (spiky) were more productive than those for which stage 1 embryos were rarely visible (smooth). This latter group develop preferably stage 3 embryos on the maturation medium containing high concentration of gellan gum. Biomass production is higher on a medium containing low concentration of gellan gum. However, sampling modalities did not affect the biomass production, and no relation was found between the biomass production and the maturation performance of each line. Stage 3 embryos developed on the medium with low concentration of gellan gum (0.45%, w/v) were shorter than those developed on medium with 0.9% of gellan gum. These short embryos were not able to germinate whereas about 48% of germination was reached with the longest embryos. The ability to develop primary root is dependent on the genotype while epicotyl elongation was observed among all lines.

Journal Article↗
PubMed2001

Comparative studies of H(2)O(2) detoxifying enzymes in green and greening barley seedlings under cadmium stress.

Cadmium(Cd) stress induced alterations in the activities of several representatives of the enzymatic antioxidant defense system such as guiacol peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were comparatively studied in green and greening barley seedlings that represent two different stages of plant development. Although roots were the main site of Cd accumulation, 1.5-3% of Cd was translocated into leaves and it induced oxidative damage which was indicated by the reduced chlorophyll and increased malondialdehyde content of the leaves. In roots of both types of seedlings exposed to various Cd concentrations, the APX activity was enhanced without any increase in the activity of POD. In leaves, however, elevated activities of both POD and APX could be observed. In roots of green seedlings at high concentration of Cd, the APX activity was reduced on the fourth day of culture but no inhibition was found in the POD activity. Leaf CAT which mainly represented the peroxisomal enzyme activity did not display any changes under Cd stress. Our results show that at both developmental stages barley seedlings exhibit a well-defined activity of the enzymatic antioxidant system, which operates differentially in roots and shoots subjected to Cd stress.

Journal Article↗
PubMed2003

Etiologic and pathogenetic factors for rotator cuff tendinopathy.

Etiologic and pathogenetic factors for rotator cuff tendinopathy, although often compartmentalized to intrinsic or extrinsic causes, have multifactorial roots. The development of animal models for the study of rotator cuff disease has increased the fund of knowledge regarding this disease and has paved the way for future studies. Further multidisciplinary studies at molecular, biomechanical, and clinical levels should be undertaken to enhance the understanding of this common disorder. Ultimately, the goals of improved care, increased comprehension, and prevention of rotator cuff tendinopathy are attainable.

Animals↗
PubMed1996

Lack of neurotrophin-3 results in death of spinal sensory neurons and premature differentiation of their precursors.

To understand mechanisms resulting in the absence of two-thirds of spinal sensory neurons in mice lacking NT-3, we have compared dorsal root ganglia development in normal and mutant embryos. The reduction in neurons, achieved by E13, results from several deficits: first, elevated neuronal apoptosis significantly reduces neuronal numbers; second, elevated neurogenesis between E11 and E12, without changes in rates of precursor proliferation or apoptosis, depletes the precursor pool; consequently, the reduced precursor pool prevents increases in neuronal numbers between E12 and E13, when most neurons are born in normal animals. Although deficits occur before final target innervation, we show that NT-3 is expressed at all stages in regions accessible to these neurons or their axons and is only restricted to final targets after innervation.

Animals↗
PubMed1999

Radiographic evaluation of mandibular third molar eruption space.

OBJECTIVE: The purpose of this study was to investigate variables in third molar and arch dimensions among subjects with impacted and erupted mandibular third molars. STUDY DESIGN: Standardized panoramic radiographs were taken for 134 subjects (60 males and 74 females with 213 third molars) with an average age of 19.8 years. For the impacted group, only those who had mesioangular inclination of the third molars were recorded. The radiographic features studied were angulation of tooth, level of eruption, development of root, mesiodistal crown width, retromolar space, and gonial angle. RESULTS: Third molar angulation in the impacted group (69 subjects with 101 third molars) averaged 16.28 degrees (SD +/- 11.88 degrees), with no significant gender differences. The retromolar space was significantly smaller in the impacted group than in the erupted group (P < .001). This space was also the only significant variable (P < .05) associated with lateral asymmetry in the eruption/impaction status of third molars. In the impacted group, 83% of subjects had third molar space/crown width ratios less than 1, whereas in the erupted group 69% had ratios of at least 1. The average space/crown width ratios in the impacted and erupted groups were 0.78 and 1.06, respectively (P < .001). The impacted and erupted groups did not differ significantly with respect to mesiodistal crown width and gonial angle. Approximately 76% of impacted third molars had complete root formation, 20% had two thirds root formation, and only 4% displayed one third root formation. Of the impacted third molars, 66% were partially erupted and the rest were unerupted. There was a strong positive relationship between frequency of third molar impaction and degree of angulation (P < .001), but the former was inversely associated with retromolar space (P < .001). CONCLUSIONS: The most significant variable associated with third molar impaction is inadequate space. The vast majority of impacted third molars had space/crown width ratios of less than 1.

Adolescent↗
PubMed2003

Long-term viability and infectivity of intraradical forms of Glomus intraradices vesicles encapsulated in alginate beads.

Intraradical vesicles of Glomus intraradices were isolated, entrapped in alginate beads, and stored at 4 degrees C for periods from 2-74 months. The beads were used to inoculate leeks grown under standard conditions for 6 wk, then development of root colonization by G. intraradices was recorded. Colonization of leeks was high (mean > 50% in length) and did not vary markedly until five years of storage. After six years of storage, the inoculum proved infective and viable.

Alginates↗
PubMed2004

Communicating original research in chemistry and related sciences.

The availability of scientific information in electronic form is the convergence of traditional journal publishing, electronic communications, and the widespread availability of computer technology. This revolution in scientific communication has its roots in developments that started in the mid-19th century and culminated with the extraordinary progress in telecommunications and computer technology in the latter years of the 20th century. Eighty-three percent of scientific journals are now available online. The benefits of electronic journals include rapid publication, instantaneous linking to external information sources, and the capability to deliver new types of information. To date neither electronic-only nor preprint servers have been well received by the chemical sciences community. Continued advances in telecommunications, computer technology, and acquisition of scientific data in structured formats hold promise for even greater advances in communication of scientific information.

Journal Article↗
PubMed1999

An example of intron junctional sliding in the gene families encoding squalene monooxygenase homologues in Arabidopsis thaliana and Brassica napus.

Sequences of three Arabidopsis thaliana and two Brassica napus cDNAs encoding squalene monooxygenase homologues (Sqp1 and Sqp2) are reported. Southern analysis confirmed that these cDNAs are derived from small gene families in both species. Expression analysis indicates that Sqp1 genes in B. napus are strongly expressed in leaves but not roots or developing seeds. Comparison of cDNA and genomic sequences indicate that the 3' splice site of an intron in these genes has undergone junctional sliding. The evolutionary significance of this phenomenon is discussed.

Amino Acid Sequence↗
PubMed2003

Development of Linum flavum hairy root cultures for production of coniferin.

Linum flavum hairy roots were initiated from leaf discs using Agrobacterium rhizogenes strains LBA9402 and TR105 though two other strains, 15834 and A4, were relatively ineffective for induction. Significant variation in coniferin accumulation was observed between hairy root lines originating from different L. flavum seedlings and/or A. rhizogenes strains. Coniferin reached 58 mg g-1 dry wt by culturing the roots in Linsmaier and Skoog (LS) medium with 2,4-dichlorophenoxyacetic acid and naphthaleneacetic acid as growth regulators.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2003

Arbuscular mycorrhiza: biological, chemical, and molecular aspects.

Mycorrhizas are the most important mutualistic symbioses on earth. The most prevalent type are the arbuscular mycorrhizas (AMs) that develop between roots of most terrestrial plants and fungal species of the Zygomycota. The AM fungi are able to grow into the root cortex forming intercellular hyphae from which highly branched structures, arbuscules, originate within cortex cells. The arbuscules are responsible for nutrient exchange between the host and the symbiont, transporting carbohydrates from the plant to the fungus and mineral nutrients, especially phosphate, and water from the fungus to the plant. Plants adapt their phosphate uptake to the interaction with the AM fungus by synthesis of specific phosphate transporters. Colonization of root cells induces dramatic changes in the cytoplasmic organization: vacuole fragmentation, transformation of the plasma membrane to a periarbuscular membrane covering the arbuscule, increase of the cytoplasm volume and numbers of cell organelles, as well as movement of the nucleus into a central position. The plastids form a dense network covering the symbiotic interface. In some of these changes, microtubules are most likely involved. With regard to the molecular crosstalk between the two organisms, a number of phytohormones (cytokinins, abscisic acid, jasmonate) as well as various secondary metabolites have been examined: (i) Jasmonates occur at elevated level, which is accompanied by cell-specific expression of genes involved in jasmonate biosynthesis that might be linked to strong carbohydrate sink function of AM roots and induced defense reactions: (ii) apocarotenoids (derivatives of mycorradicin and glycosylated cyclohexenones) accumulate in most mycorrhizal roots examined so far. Their biosynthesis via the nonmevalonate methylerythritol phosphate (MEP) pathway has been studied resulting in new insights into AM-specific gene expression and biosynthesis of secondary isoprenoids.

Carbohydrates↗
PubMed2003

Molecular characterization of Brassica napus NAC domain transcriptional activators induced in response to biotic and abiotic stress.

Subtractive expressed sequence tag analysis and screening of cDNA libraries derived from Brassica napus leaves subjected to mechanical wounding, flea beetle feeding or cold temperatures revealed eight genes encoding NAC-domain transcription factors. The genes were found to be differentially regulated in response to biotic and abiotic stresses including wounding, insect feeding, Sclerotinia sclerotiorum infection, cold shock and dehydration. Five BnNAC proteins were orthologous to Arabidopsis thaliana ATAF1 or ATAF2 and gave rise to developmental abnormalities similar to the A. thaliana nam and cuc mutants when expressed ectopically in A. thaliana. Transgenic lines expressing BnNAC14, exhibited large leaves, thickened stems and hyper-developed lateral root systems similar to that observed with A. thaliana NAC1, but also were delayed in bolting and lacked an apical dominant tap root. Several of the BnNAC proteins were capable of activating gene expression in yeast and recognized an element within the CaMV35S promoter. A yeast two-hybrid screen revealed that BnNAC14 interacted with other select BnNAC proteins in vitro and identified an additional BnNAC gene, BnNAC485. The protein interaction and transcriptional activation domains were mapped by deletion analysis.

Amino Acid Sequence↗
PubMed1995

Analysis of Arabidopsis mutants deficient in flavonoid biosynthesis.

Eleven loci that play a role in the synthesis of flavonoids in Arabidopsis are described. Mutations at these loci, collectively named transparent testa (tt), disrupt the synthesis of brown pigments in the seed coat (testa). Several of these loci (tt3, tt4, tt5 and ttg) are also required for the accumulation of purple anthocyanins in leaves and stems and one locus (ttg) plays additional roles in trichome and root hair development. Specific functions were previously assigned to tt1-7 and ttg. Here, the results of additional genetic, biochemical and molecular analyses of these mutants are described. Genetic map positions were determined for tt8, tt9 and tt10. Thin-layer chromatography identified tissue- and locus-specific differences in the flavonols and anthocyanidins synthesized by mutant and wild-type plants. It was found that UV light reveals distinct differences in the floral tissues of tt3, tt4, tt5, tt6 and ttg, even though these tissues are indistinguishable under visible light. Evidence was also uncovered that tt8 and ttg specifically affect dihydroflavonol reductase gene expression. A summary of these and previously published results are incorporated into an overview of the genetics of flavonoid biosynthesis in Arabidopsis.

Acyltransferases↗
PubMed2001

A novel gene mutation that confers abnormal patterns of beta-carotene accumulation in cauliflower (Brassica oleracea var. botrytis).

The Or gene of cauliflower (Brassica oleracea var. botrytis) causes many tissues of the plant to accumulate carotenoids and turn orange, which is suggestive of a perturbation of the normal regulation of carotenogenesis. A series of experiments to explore the cellular basis of the carotenoid accumulation induced by the Or gene was completed. The Or gene causes obvious carotenoid accumulation in weakly or unpigmented tissues such as the curd, pith, leaf bases and shoot meristems, and cryptically in some cells of other organs, including the roots and developing fruits. The dominant carotenoid accumulated is beta-carotene, which can reach levels that are several hundred-fold higher than those in comparable wild-type tissues. The beta-carotene accumulates in plastids mainly as a component of massive, highly ordered sheets. The Or gene does not affect carotenoid composition of leaves, nor does it alter color and chromoplast appearance in flower petals. Interestingly, mRNA from carotenogenic and other isoprenoid biosynthetic genes upstream of the carotenoid pathway was detected both in orange tissues of the mutant, and in comparable unpigmented wild-type tissues. Thus the unpigmented wild-type tissues are likely to be competent to synthesize carotenoids, but this process is suppressed by an unidentified mechanism. Our results suggest that the Or gene may induce carotenoid accumulation by initiating the synthesis of a carotenoid deposition sink in the form of the large carotenoid-sequestering sheets.

Blotting, Northern↗
PubMed2006

Molecular evidence for deep evolutionary roots of bilaterality in animal development.

Nearly all metazoans show signs of bilaterality, yet it is believed the bilaterians arose from radially symmetric forms hundreds of millions of years ago. Cnidarians (corals, sea anemones, and "jellyfish") diverged from other animals before the radiation of the Bilateria. They are diploblastic and are often characterized as being radially symmetrical around their longitudinal (oral-aboral) axis. We have studied the deployment of orthologs of a number of family members of developmental regulatory genes that are expressed asymmetrically during bilaterian embryogenesis from the sea anemone, Nematostella vectensis. The secreted TGF-beta genes Nv-dpp, Nv-BMP5-8, six TGF-beta antagonists (NvChordin, NvNoggin1, NvNoggin2, NvGremlin, NvFollistatin, and NvFollistatin-like), the homeodomain proteins NvGoosecoid (NvGsc) and NvGbx, and the secreted guidance factor, NvNetrin, were studied. NvDpp, NvChordin, NvNoggin1, NvGsc, and NvNetrin are expressed asymmetrically along the axis perpendicular to the oral-aboral axis, the directive axis. Furthermore, NvGbx, and NvChordin are expressed in restricted domains on the left and right sides of the body, suggesting that the directive axis is homologous with the bilaterian dorsal-ventral axis. The asymmetric expression of NvNoggin1 and NvGsc appear to be maintained by the canonical Wnt signaling pathway. The asymmetric expression of NvNoggin1, NvNetrin, and Hox orthologs NvAnthox7, NvAnthox8, NvAnthox1a, and NvAnthox6, in conjunction with the observation that NvNoggin1 is able to induce a secondary axis in Xenopus embryos argues that N. vectensis could possess antecedents of the organization of the bilaterian central nervous system.

Animals↗
PubMed1994

Controlled expression of plastid transgenes in plants based on a nuclear DNA-encoded and plastid-targeted T7 RNA polymerase.

Phage T7 RNA polymerase has been used extensively in Escherichia coli for high-level expression of selected genes placed under the control of the phage T7 gene 10 promoter. We have constructed an analogous system for use in plastids of higher plants. A T7 RNA polymerase chimeric gene containing a cauliflower mosaic virus 35S promoter and a tobacco ribulose-bisphosphate carboxylase/oxygenase small-subunit chloroplast transit-peptide sequence was introduced into tobacco by nuclear transformation. Stable plastid transformation of tobacco expressing the T7 RNA polymerase activity with a T7 promoter/beta-glucuronidase (GUS) reporter gene construct resulted in expression of GUS mRNA and enzyme activity in all tissues examined. Expression of GUS activity was extremely high in mature leaves, moderate in young leaves and petals, and low in stems, roots, and developing seeds. Plastid transformation of wild-type tobacco with the same chimeric GUS gene resulted in undetectable levels of GUS mRNA and enzyme activity. Genetic crosses demonstrated that a silent T7/GUS reporter gene could be activated in the F1 generation by transmission of an active nuclear T7 RNA polymerase gene from the male parent.

Base Sequence↗