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At least 1,387 records · Page 77Linked to original sources
PubMed2005

Opposite patterns in the annual distribution and time-course of endogenous abscisic acid and indole-3-acetic acid in relation to the periodicity of cambial activity in Eucommia ulmoides Oliv.

The seasonal change of free abscisic acid (ABA) and indole-3-acetic acid (IAA) and their relationship with the cambial activity in Eucommia ulmoides trees were investigated by ABA and IAA immunolocalization using primary polyclonal and rhodamine-red fluorescing secondary antibodies, ABA and IAA quantification using high performance liquid chromatography (HPLC), and systematic monitoring of vascular cell layers production. ABA and IAA clearly displayed opposite annual distribution patterns. In the active period (AP), both immunolocalization and HPLC detected an abrupt decrease of ABA, reaching its lowest level in the summer. During dormancy, ABA started increasing in the first quiescence (Q1) (autumn), peaked in the rest (winter), and gradually decreased from the onset of the second quiescence (Q2) (the end of winter). IAA showed a reverse pattern to that of ABA: it sharply increased in AP, but noticeably decreased from the commencement of Q1. Longitudinally, the ABA distribution increased apico-basally, contrasting with IAA. Laterally, most of the ABA was located in mature vascular tissues, whereas the IAA essentially occurred in the cambial region. The concomitant IAA-ABA distribution and seasonal changes in vascular tissues greatly correlated with xylem and phloem cell production, and late wood differentiation and maturation. Interestingly, the application of exogenous ABA to quiescent E. ulmoides branches, in a water-culture system, inhibited external IAA action on cambial activity reactivation. These results suggest that, in E. ulmoides, ABA and IAA might probably interact in the cambial region. The annual cambial activity could be influenced by an IAA:ABA ratio; and ABA might play a key role in vascular cambium dormancy in higher plants. The relationship between hormonal changes and the (particular) annual life cycle of E. ulmoides is also discussed.

Abscisic Acid↗
PubMed1992

Studies on the growth and indole-3-acetic acid and abscisic acid content of Zea mays seedlings grown in microgravity.

Measurements were made of the fresh weight, dry weight, dry weight-fresh weight ratio, free and conjugated indole-3-acetic acid, and free and conjugated abscisic acid in seedlings of Zea mays grown in darkness in microgravity and on earth. Imbibition of the dry kernels was 17 h prior to launch. Growth was for 5 d at ambient orbiter temperature and at a chronic accelerational force of the order of 3 x 10(-5) times earth gravity. Weights and hormone content of the microgravity seedlings were, with minor exceptions, not statistically different from seedlings grown in normal gravity. The tissues of the shuttle-grown plants appeared normal and the seedlings differed only in the lack of orientation of roots and shoots. These findings, based upon 5 d of growth in microgravity, cannot be extrapolated to growth in microgravity for weeks, months, and years, as might occur on a space station. Nonetheless, it is encouraging, for prospects of bioregeneration of the atmosphere and food production in a space station, that no pronounced differences in the parameters measured were apparent during the 5 d of plant seedling growth in microgravity.

Abscisic Acid↗
PubMed2000

Characterization of auxin conjugates in Arabidopsis. Low steady-state levels of indole-3-acetyl-aspartate, indole-3-acetyl-glutamate, and indole-3-acetyl-glucose.

Amide-linked indole-3-acetic acid (IAA) conjugates constitute approximately 90% of the IAA pool in the dicot Arabidopsis, whereas ester-linked conjugates and free IAA account for approximately 10% and 1%, respectively when whole seedlings are measured. We show here that IAA-aspartate Asp, IAA-glutamate (Glu), and IAA-glucose (Glc) are present at low levels in Arabidopsis. Nine-day-old wild-type Arabidopsis seedlings yielded 17.4 +/- 4.6 ng g(-1) fresh weight IAA-Asp and 3.5 +/- 1.6 ng g(-1) fresh weight IAA-Glu, and IAA-Glc was present at 7 to 17 ng g(-1) fresh weight in 12-d-old wild-type seedlings. Total IAA content in 9-d-old Arabidopsis seedlings was 1, 200 +/- 178 ng g(-1) fresh weight, so these three IAA conjugates together made up only 3% of the conjugate pool throughout the whole plant. We detected less than wild-type levels of IAA-Asp and IAA-Glu (7.8 +/- 0.4 ng g(-1) fresh weight and 1.8 +/- 0.3 ng g(-1) fresh weight, respectively) in an Arabidopsis mutant that accumulates conjugated IAA. Our results are consistent with IAA-Asp, IAA-Glu, and IAA-Glc being either minor, transient, or specifically localized IAA metabolites under normal growth conditions and bring into question the physiological relevance of IAA-Asp accumulation in response to high concentrations of exogenous IAA.

Arabidopsis↗
PubMed1988

Effects of cations on hormone transport in primary roots of Zea mays.

We examined the influence of aluminum and calcium (and certain other cations) on hormone transport in corn roots. When aluminum was applied unilaterally to the caps of 15 mm apical root sections the roots curved strongly away from the aluminum. When aluminum was applied unilaterally to the cap and 3H-indole-3-acetic acid was applied to the basal cut surface twice as much radioactivity (assumed to be IAA) accumulated on the concave side of the curved root as on the convex side. Auxin transport in the apical region of intact roots was preferentially basipetal, with a polarity (basipetal transport divided by acropetal transport) of 6.3. In decapped 5 mm apical root segments, auxin transport was acropetally polar (polarity = 0.63). Application of aluminum to the root cap strongly promoted acropetal transport of auxin reducing polarity from 6.3 to 2.1. Application of calcium to the root cap enhanced basipetal movement of auxin, increasing polarity from 6.3 to 7.6. Application of the calcium chelator, ethylene-glycol-bis-(beta-aminoethylether)-N,N,N',N'-tetraacetic acid, greatly decreased basipetal auxin movement, reducing polarity from 6.3 to 3.7. Transport of label after application of tritiated abscisic acid showed no polarity and was not affected by calcium or aluminum. The results indicate that the root cap is particularly important in maintaining basipetal polarity of auxin transport in primary roots of corn. The induction of root curvature by unilateral application of aluminum or calcium to root caps is likely to result from localized effects of these ions on auxin transport. The findings are discussed relative to the possible role of calcium redistribution in the gravitropic curvature of roots and the possibility of calmodulin involvement in the action of calcium and aluminum on auxin transport.

Abscisic Acid↗
PubMed2002

Molecular genetics of auxin signaling.

The plant hormone auxin is a simple molecule similar to tryptophan, yet it elicits a diverse array of responses and is involved in the regulation of growth and development throughout the plant life cycle. The ability of auxin to bring about such diverse responses appears to result partly from the existence of several independent mechanisms for auxin perception. Furthermore, one prominent mechanism for auxin signal transduction involves the targeted degradation of members of a large family of transcriptional regulators that appear to participate in complex and competing dimerization networks to modulate the expression of a wide range of genes. These models for auxin signaling now offer a framework in which to test how each specific response to auxin is brought about.

Amino Acid Sequence↗
PubMed1986

[Pharmacological studies on proglumetacin maleate, a new non-steroidal anti-inflammatory drug. (3) Damaging effects on the gastrointestinal tract].

Damaging effects on the gastrointestinal tract of proglumetacin maleate (PGM), a new indomethacin (IND) derivative, were examined in comparison with those of IND. Gastric and small intestinal lesions were maximum 4 and 24 hr after a single oral administration of PGM, respectively. Ulcerogenic effects of PGM on the gastric mucosa were approximately 1/7 and 1/10 times as potent as those of IND on a molar ratio 4 hr after single oral dosing to fasting and feeding rats, respectively. PGM was also less active on the small intestinal mucosa 24 hr after single oral dosing. After repeated dosing for 7 days, ulcerogenic effects of PGM were about 1/3 and 1/2 times more potent than those of IND on the gastric and the small intestinal mucosa, respectively. The weak ulcerogenicity of PGM appears to be due to the fact that it has little direct action on the gastrointestinal mucosa. On the other hand, protective effects of PGM on diarrhea induced by arachidonic acid in mice were about 1/2 times as potent as those of IND in both 1 and 4 hr pretreatments. So PGM must have less inhibitory effects on prostaglandin biosynthesis in the intestine than IND. PGM is a safer drug than IND because it has less damaging effect on the gastrointestinal mucosa. Therefore, it may be much more useful for the treatment of chronic inflammatory disorders like rheumatoid arthritis.

Administration, Oral↗
PubMed2002

Nutritional profile of food yeast Kluyveromyces fragilis biomass grown on whey.

Biomass of food yeast Kluyveromyces fragilis (MTCC 188) grown on deproteinized whey supplemented with 0.8% diammonium hydrogen phosphate and 10 ppm indole-3-acetic acid, had a crude protein content of 37%. The true protein content based on nitrogen fractionation procedure was 28.1%. Total nucleic acid content was 4.82%. This amount does not appear to be toxicologically offensive. Crude fiber, ash, and lipid content of K.fragilis dry cells were found to be 4.9%, 16%, and 7.8%, respectively. Essential fatty acids of both omega-3 and omega-6 series were found present in the fat of the yeast and represented 21.5% of the total fatty acids. All the essential amino acids were present in the proteins of K. fragilis; however, sulfur containing amino acids were found in lower amounts. Calculated protein scores indicate moderate biological value. B vitamins in the biomass were present as expected, but folic acid and pyridoxine were present in high concentration.

Amino Acids↗
PubMed2000

Early physiological and cytological events induced by wounding in potato tuber.

The response of potato tuber (Solanum tuberosum L. cv. Kennebec) to mechanical wounding was investigated at different times. Changes in the levels of indole-3-acetic acid (IAA), polyunsaturated fatty acids (PUFAs) and lipid hydroperoxides (LOOHs) were monitored up to 120 min after wounding and related to the cytological events occurring up to 24 h. Twenty minutes after injury, an increase in IAA and LOOH levels and a decrease in the levels of PUFAs was observed. Wounding induced mitoses in differentiated (parenchyma) cells starting at 120 min, and promoted an increase of mitotic activity in the meristematic cells (procambium and bud dome), after 360 min. The inhibition of the increase in LOOHs and IAA by lipoxygenase (LOX) inhibitors, as well as the ability of in vitro peroxidated linoleic acid to enhance IAA production, suggest a close relationship among lipoperoxidation, IAA and mitotic activity in the response of potato tuber cells to injury, resulting in a specific growth response, i.e. bud growth and periderm formation.

Fatty Acids, Unsaturated↗
PubMedDate not supplied

[Effect of gibberellin and auxin on the synthesis of abscisic acid and ethylyne in buds of dormant and sprouting potato tuber].

Gibberellic and beta-indolylacetic acids at concentrations of 10(-7)-10(-5) M were shown to change the hormonal status and duration of dormancy in potato tubers. Gibberellic acid shortened the dormancy and decreased the contents of abscisic acid and ethylene in apical meristems. beta-Indolylacetic acid elongated the dormancy, decreased abscisic acid production, but caused a more than tenfold increase in the production of ethylene by apical tissues. The data suggest that beta-indolylacetic acid and ethylene, as well as gibberellic and abscisic acids, are involved in the regulation of dormancy in potato tubers.

Abscisic Acid↗