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At least 253 records · Page 14Linked to original sources
PubMed2001

[Study on effect of ABA, PEG4000 and AgNO3 on number of somatic embryos of Larix Principis-Rupprechtii by 311-A regression design].

This paper, the effects of ABA, PEG400 and AgNO3 on the number of somatic embryos of Larix Principis-Rupprechtii were carried out by 311-A regression design. The regression equation was established which expresses the number of somatic embryos of Larix Principis-Rupprechtii as function, and the ABA, PEG400 and AgNO3 on as variable respectively. Using the regression equation, the single factor effect and mutual effect between the number of somatic embryos of Larix Principis-Rupprechtii and ABA, PEG400 and AgNO3 was studied; the optimum concentration recipes can be obtained by computer processing, that are ABA: 18.9138 mg/L, PEG400: 88.8007 g/L and AgNO3: 10.7513 mg/L, the target somatic embryos number is 107.5278 each gram callus. The results of experiment showed that this method is simple, practical and rapid for selecting several hormone category and concentration recipes media of conifer somatic embryogenesis.

Abscisic Acid↗
PubMed2000

[Effects of Ca2+, ABA and H3PO4 on relaxing stress of Na2CO3 and NaCl].

Two groups of Aneurolepidium chinense seedlings were stressed by 300 mmol.L-1 NaCl and 100 mmol.L-1 Na2CO3, respectively and the effect of ABA, Ca2+ and H3PO4 on relaxing their stress was studied. The results show that external Ca2+, ABA and H3PO4 could obviously mitigat the inhibitory effect of NaCl and NaCO3 on seedling growth. In the treatment of Na2CO3, praying it on leaves had a better effect than root-irrigating, while in the treatment of NaCl, there was no significant difference. The effect of Ca(NO3)2 was much better than that of CaCl2, and of mingling CaCl2 and ABA had a much better effect than CaCl2 or ABA alone.

Abscisic Acid↗
PubMed2001

The biological activity of ABA-1-like protein from Ascaris lumbricoides.

The elevation of non-specific IgE (total IgE) in Ascaris infection can be seen one week after infection, and reaches a peak after approximately two weeks. It has been reported that ABA-1 protein is the main constituent in the pseudocoelomic fluid of Ascaris suum. To investigate the effect of the ABA-1-like protein from Ascaris lumbricoides (ALB), the cDNA was cloned by reverse transcriptase polymerase chain reaction, using original primers based on the consensus sequences of ABA-1 and TBA-1, that is an ABA-1-like protein from Toxocara canis. The clone was sequenced, we constructed the recombinant polyprotein of ALB (rALB14 and rALB7) based on the ALB sequence, and rALB was administrated to BALB/c mice. Fourteen days after inoculation with rALB14 which is the full length of ALB, the elevation of total IgE which we supposed to contain non-specific IgE was observed, and the results were as we expected. Furthermore, in an in-vitro experiment, we confirmed that the spleen cells proliferated when stimulated by rALB14 and concanavalin A. Therefore, the whole conformation of ALB is considered to be involved in the elevation of non-specific IgE, and is involved in the activation of T cells.

Allergens↗
PubMed2006

[Mathematical simulation of stomatal regulation involving root-sourced signaling ABA under soil drought condition].

A stomatal conduction model consisting of root water uptake model and stomatal control model under the participation of root-sourced signal ABA was developed in this paper, which considered the root water uptake effect function and root length density distribution function during root-sourced signal production. This model was used to simulate the course of maize stomatal conduction controlled by the root-sourced signal in field. The results showed that owing to the considering of the influence of root water uptake effect function and root length density distribution in soil profile, this model could more accurately depict the intensity of root water uptake, the ABA concentration produced in root system, the root ABA concentration in different soil layers and in xylem, and the controlling process of plant stomatal regulation by root-sourced ABA.

Abscisic Acid↗
PubMed1996

In vivo biocompatibility study of ABA triblock copolymers consisting of poly(L-lactic-co-glycolic acid) A blocks attached to central poly(oxyethylene) B blocks.

Films of three ABA-block copolymers composed of lactic-co-glycolic acid A blocks and poly(oxyethylene) (PEO) B blocks and one random lactic-co-glycolic acid copolymer (PLG) were studied to investigate the influence of different polymer compositions and molecular weights on the tissue reaction, appearance of toxic degradation products, and swelling behavior in the cage implant system in rats. The inflammatory tissue reaction was followed over a 21-day implantation period by monitoring the leukocyte concentration, the extracellular acid, and alkaline phosphatase activities in a quantitative manner. Size and density of adherent macrophages and foreign body giant cells on the film surfaces were determined. The ABA and PLG implants caused only a minimal inflammatory reaction, as characterized by a low concentration of leukocytes during the implantation period when compared to empty cage controls. The content of PEO had an influence on the density of the adherent cells on the surface of the polymer film. An increase in PEO content and molecular weight decreased the cellular density during the implantation period. As demonstrated by scanning electron microscopy, no degradation was observed for all polymers during the implantation period. Our results demonstrate that the ABA block copolymers and PLG copolymer, are equally well tolerated in the cage implant test system.

Alkaline Phosphatase↗
PubMed2000

Cytoskeleton-induced alterations of the lectin activity in winter wheat under cold hardening and abscisic acid (ABA).

The roots and leaves of 7-day seedlings of three winter wheat cultivars differing in frost resistant were used to study changes in lectin activity under cytoskeleton modifiers (DMSO-7%; colchicine-1 m m; oryzalin-15 microm; cytochalasin B-15 microm) of non-hardened (23 degrees C) and hardened (2-3 degrees C, 3-7 day) plants. Plants were grown with ABA (30 microm) or without ABA. Pretreatment with colchicine, oryzalin [inhibitors of microtubules (MT) polymerization], cytochalasin B [inhibitor of microfilament (MF) polymerization] increased the activity of cell wall lectins, although pretreatment with DMSO (stabilizer of microtubules) decreased the activity. Both hardening and ABA decreased the effect of the cytoskeletal modifiers. These results could be explained by the appearance of tolerant MTs with less affinity. It is probable that increase in the activity of cell wall lectins may be the compensatory mechanism which stabilizes the cytoskeleton structure in conditions tending to disrupt it. The genotype with low resistance had higher sensitivity of lectin activity to cytoskeleton modifiers than the frost resistant genotype. The results suggest that leaves have more stable MTs and MFs and stronger MT-MF binding than roots.

Abscisic Acid↗
PubMed1996

Differential regulation of two ABA-inducible genes from Craterostigma plantagineum in transgenic Arabidopsis plants.

In Craterostigma plantagineum the CDeT-6-19 and CDeT-27-45 genes are expressed following desiccation and/or ABA treatment. Their promoters were fused to the beta-glucuronidase reporter gene (GUS) and tested in transgenic Arabidopsis. GUS activity was measured in mature Arabidopsis seeds, and the responsiveness to ABA in vegetative tissue was found to be limited to the early developmental stages. When transgenic plants were crossed with plants over-expressing the ABI3 gene, it was observed that ABI3 is not required for ABA induction of the CDeT-6-19 promoter, whereas it is crucial for expression of the CDeT-27-45 promoter.

Abscisic Acid↗
PubMed2006

Novel calcium-binding GTPase (AtCBG) involved in ABA-mediated salt stress signaling in Arabidopsis.

We have identified a novel Ca(2+)-signal sensing GTPase (643 amino acid residues with an estimated molecular mass of 79 kDa) from the Arabidopsis genome database. This protein contains a RHO-like GTPase domain at the N-terminus (15-184 amino acids) and two calcium-binding EF-hand motifs (199-227 and 319-347 amino acids, respectively). It has the capability to bind calcium and hydrolyze GTP; in addition, its GTPase activity is regulated by changes in Ca(2+) concentration. The expression of this gene was induced by ABA and salt stresses, and specific knock-out mutants were highly sensitive to ABA and salt treatments. These findings suggest that this protein is a novel ABA- and salt stress-related Ca(2+) signal transducer.

Abscisic Acid↗
PubMed2006

A rice dehydration-inducible SNF1-related protein kinase 2 phosphorylates an abscisic acid responsive element-binding factor and associates with ABA signaling.

By a differential cDNA screening technique, we have isolated a dehydration-inducible gene (designated OSRK1) that encodes a 41.8 kD protein kinase of SnRK2 family from Oryza sativa. The OSRK1 transcript level was undetectable in vegetative tissues, but significantly increased by hyperosmotic stress and Abscisic acid (ABA). To determine its biochemical properties, we expressed and isolated OSRK1 and its mutants as glutathione S-transferase fusion proteins in Escherichia coli. In vitro kinase assay showed that OSRK1 can phosphorylate itself and generic substrates as well. Interestingly, OSRK1 showed strong substrate preference for rice bZIP transcription factors and uncommon cofactor requirement for Mn(2+) over Mg(2+). By deletion of C-terminus 73 amino acids or mutations of Ser-158 and Thr-159 to aspartic acids (Asp) in the activation loop, the activity of OSRK1 was dramatically decreased. OSRK1 can transphosphorylate the inactive deletion protein. A rice family of abscisic acid-responsive element (ABRE) binding factor, OREB1 was phosphorylated in vitro by OSRK1 at multiple sites of different functional domains. MALDI-TOF analysis identified a phosphorylation site at Ser44 of OREB1 and mutation of the residue greatly decreased the substrate specificity for OSRK1. The recognition motif for OSRK1, RQSS is highly similar to the consensus substrate sequence of AMPK/SNF1 kinase family. We further showed that OSRK1 interacts with OREB1 in a yeast two-hybrid system and co-localized to nuclei by transient expression analysis of GFP-fused protein in onion epidermis. Finally, ectopic expression of OSRK1 in transgenic tobacco resulted in a reduced sensitivity to ABA in seed germination and root elongation. These findings suggest that OSRK1 is associated with ABA signaling, possibly through the phosphorylation of ABF family in vivo. The interaction between SnRK2 family kinases and ABF transcription factors may constitute an important part of cross-talk mechanism in the stress signaling networks in plants.

Abscisic Acid↗
PubMed1984

A complete set of overlapping cosmid clones of M-ABA virus derived from nasopharyngeal carcinoma and its similarity to other Epstein-Barr virus isolates.

DNA of the transforming, nondefective Epstein-Barr virus (EBV) strain M-ABA, which is derived from nasopharyngeal carcinoma cells, was cloned as large overlapping pieces into the cosmid pHC79 . The termini were cloned from closed circular virus DNA molecules out of M-ABA cell DNA in phage lambda L47 . The large overlapping clones were used to prepare a library of subclones with inserts of 1-15 kb. A detailed restriction enzyme map of M-ABA virus DNA reveals the close similarity to isolates from other sources. The high number of tandem repeats in EBV DNA stresses the importance of using cloning vectors that can be propagated in recA- Escherichia coli hosts.

Carcinoma↗
PubMed2005

Role of a Ca2+-ATPase induced by ABA and IAA in the generation of specific Ca2+ signals.

The control of the Ca(2+)-ATPase gene (LCA1) that encodes two different membrane-located isoforms by two antagonic phytohormones, ABA and IAA, has been investigated. Strikingly both the growth regulators induce the LCA1 expression. By using a protoplast transient system, the cis-acting DNA elements responding to both, abiotic stress (ABA) and normal development (IAA), are dissected. ABA triggered a 4-fold increase in the GUS-activity. A single ACGT motif responsible for most of the LCA1 mRNA induction was localized at an unexpectedly large distance (1577 bp) upstream of the translational start. In the case of IAA, although there is a TGTCTC sequence that is known to be an important cis-acting element, two TGA motifs play a more critical role. It is proposed that the Ca(2+)-ATPase isoforms might intervene in the generation of specific Ca(2+) signals by restoring steady-state Ca(2+) levels, modulating both frequency and amplitude of Ca(2+) waves via wave interference.

Abscisic Acid↗
PubMed2006

A new non-azole inhibitor of ABA 8'-hydroxylase: effect of the hydroxyl group substituted for geminal methyl groups in the six-membered ring.

We designed and synthesized AHI4 that has an axial hydroxyl group instead of geminal methyl groups at C-6' of AHI1, previously reported as a lead compound for the development of non-azole inhibitors of ABA 8'-hydroxylase. (+)-AHI4 competitively inhibited 8'-hydroxylation of ABA by recombinant CYP707A3. The K(I) value was found to be 0.14 microM, 10-fold less than that of (+)-AHI1, suggesting that enzyme affinity increased by a factor of 10 due to substitution of the hydroxyl group by the geminal methyls at C-6'. This finding should assist in the design of more effective, non-azole ABA 8'-hydroxylase inhibitors.

Azoles↗
PubMed2005

Is IS(ABA-1) customized for Acinetobacter?

An insertion sequence (IS(ABA-1)) was identified in Acinetobacter spp., but not in Enterobacteriacea and Pseudomonas aeruginosa. Numerous copies of the IS were identified in Acinetobacter strains containing the element. In one of the Acinetobacter baumannii strains, IS(ABA-1) was identified adjacent to sulII and transcription of the resistance gene is presumed to be dependent on promoter sequences within the IS. Since the IS is adjacent to ampC and bla(OXA) in this A. baumannii strain, it may be that IS(ABA-1) plays an important role in the expression of antibiotic resistance genes in this genus.

Acinetobacter↗
PubMed2006

ABA and BAB type triblock copolymers of PEG and PLA: a comparative study of drug release properties and "stealth" particle characteristics.

We synthesized two types of triblock copolymers containing PEG and PLA as controlled release carriers of hydrophobic drugs: these are the ABA type (PLA-PEG-PLA) and the BAB type (PEG-PLA-PEG). These polymers are amphiphilic and can form nanomicelles (40-200nm) in aqueous medium. On the surface of PLA-PEG-PLA (ABA) type nanomicelles, the PEG content was enhanced somewhat over the bulk amount; whereas in the PEG-PLA-PEG (BAB type), surface segregation was much higher. The copolymers tested can entrap 35% of paclitaxel by weight on the average. In general, the diffusion-controlled release of paclitaxel is slower for the BAB polymers; furthermore, the actual release rates are influenced by the PLLA lengths in the BAB copolymers. Surface PEG contents influence the "stealth" characteristics of the nanomicelles. Compared with PLA particles, all nanomicellar particles tested, of both BAB and ABA types, showed a four-fold reduction in monocyte cell uptake, with the BAB type copolymer exhibiting a lesser uptake.

Delayed-Action Preparations↗
PubMed2001

Rice salT promoter is activated in Papaver somniferum and Nicotiana tabacum transgenic cells in the absence of exogenous ABA.

With the aim of modifying secondary metabolism in Opium poppy (Papaver somniferum) and tobacco (Nicotiana tabacum) cells, gene transfer was performed using the sam1 gene from Arabidopsis thaliana under the control of the salT promoter. This promoter is induced by ABA in rice and in tobacco and we have shown that it is also induced in poppy cells (gus gene). Putatively transformed poppy and tobacco cell lines with the sam1 gene were obtained. In the absence of exogenous inducer we noticed the expression of the transgene resulting in a significant increase of SAM-S activity in all tested transformants of poppy and in half the transgenic tobacco cell lines tested. Addition of ABA to the culture medium failed to enhance the expression of the transgene in both species and resulted in a decrease of the sam1 gene expression in some cell lines. Since the salT promoter is induced by exogenous ABA in both species (gus reporter gene), we suggest a partial sam1 transgene inactivation in certain cell lines. These results show that the efficiency of a regulatory sequence may be different when fused with a reporter gene (gus) compared to fusion with a gene belonging to the housekeeping family (sam1).

Journal Article↗
PubMed1998

Plasma protein adsorption on biodegradable microspheres consisting of poly(D,L-lactide-co-glycolide), poly(L-lactide) or ABA triblock copolymers containing poly(oxyethylene). Influence of production method and polymer composition.

Biodegradable particulate systems have been considered as parenteral drug delivery systems. The adsorption of plasma proteins on micro- and nanoparticles is determined by the surface properties and may, in turn, strongly influence the biocompatibility and biodistribution of both carriers. In the present study the influence of the polymer composition and the production method of microspheres on the in vitro plasma protein adsorption were investigated using two-dimensional electrophoresis (2-DE). Microparticles were prepared from poly(l-lactide) (l-PLA), poly(d,l-lactide-co-glycolide) (PLGA), and ABA triblock copolymers containing hydrophilic poly(oxyethylene) (B-blocks) domains connected to hydrophobic polyesters (A-blocks). Two different microencapsulation methods were employed, namely the w/o/w emulsion solvent evaporation method and the spray-drying technique. It could be demonstrated that the polymer composition and, especially, the encapsulation technique, influenced the interactions with plasma proteins significantly. For example, the percentages of several apolipoproteins in the plasma protein adsorption patterns of spray-dried PLGA- and l-PLA-particles were distinctly higher when compared to the adsorption patterns of the particles produced by the w/o/w-technique. Some adsorbed proteins were found to be characteristic or even specific for particles produced by the same method or consisting of identical polymers. Polyvinyl alcohol used as stabilizer in the w/o/w-technique may decisively influence the surface properties relevant for protein adsorption. The plasma protein adsorption on particles composed of ABA copolymers was drastically reduced when compared to microspheres made from pure polyesters. The adsorption patterns of ABA-particles were dominated by albumin. The plasma protein adsorption patterns detected on the different microspheres are likely to affect their in vivo performance as parenteral drug delivery systems.

Adsorption↗
PubMed2002

Tetanus toxoid microspheres consisting of biodegradable poly(lactide-co-glycolide)- and ABA-triblock-copolymers: immune response in mice.

Tetanus toxoid (TT) was microencapsulated using poly(lactide-co-glycolide) (PLGA) with molar compositions of 50:50, 75:25 or an ABA-triblock-copolymer consisting of PLGA A-blocks attached to a central polyoxyethylene-B-block with a W/O/W (water/oil/water) double emulsion technique. The TT microspheres (MS) were evaluated with respect to protein integrity during antigen release in-vitro and compared with aluminum-adsorbed TT in a mouse model for in-vivo induction of tetanus-specific antibodies as well as protection against a subcutaneous tetanus toxin challenge. The more hydrophilic ABA-triblock-copolymer protected the TT against the deleterious microenvironmental conditions in the degrading MS and provided a prolonged antigen release. In spite of the distinct differences in the in-vitro release patterns MS from PLGA and ABA-triblock-copolymer did not show significant differences in the in-vivo induction of tetanus-specific antibodies. Both preparations elicited antibody titers nearly as high as conventional aluminum-adsorbed TT, which lasted for 29 weeks and were protective against a challenge with 100 x LD(50) tetanus toxin. TT-MS boosted mice which were preimmunized with aluminum-adsorbed as well as with microencapsulated TT. TT-MS are suitable candidates for single shot vaccine delivery systems which elicit a long lasting and protecting immune response.

Animals↗
PubMed1999

In vitro studies on the cellular uptake of melanoma imaging aminoalkyl-iodobenzamide derivatives (ABA).

The cellular uptake of 11 radioiodinated aminoalkyl-iodobenzamides (ABA) was studied using cultivated murine melanoma cells (B16/C3). All derivatives showed a high uptake (up to about 80%) of radioactivity in melanotic melanoma cells; hence, accumulation of all compounds radioiodinated in the ortho position was reduced by approximately 30%. Using the compound para-[131I]iododiethyl-aminoethylbenzamide (p-131I-ABA-2-2) a close correlation of the cellular melanin content with the tracer uptake (R2 = 0.95) was verified. The presence of extracellular melanin, however, had no effect on the cellular tracer uptake. Because the accumulation was independent of the specific activity of p-131I-ABA-2-2, a significant contribution to the uptake process by binding to receptor sites could be excluded.

Benzamides↗