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At least 127 records · Page 7Linked to original sources
PubMed2025

Altered ruminal microbiome tryptophan metabolism and their derived 3-indoleacetic acid inhibit ruminal inflammation in subacute ruminal acidosis goats.

BACKGROUND: Subacute ruminal acidosis (SARA) is a digestive disorder that often severely jeopardizes the health and lactation performance of ruminants fed a high-energy diet. Different dairy ruminants exhibit varying degrees of inflammation accompanied by variations in the rumen microbiota when SARA occurs. Our understanding of the occurrence of SARA and varying degrees of rumen epithelial inflammation is lacking. Hence, we performed rumen metagenomic, metagenome-assembled genome and metabolomic analyses, with transcriptome and single-nucleus RNA sequence analyses, to explore the microbial mechanism of SARA occurrence and different degrees of inflammation. RESULTS: A total of 36 goats fed two diets with gradually increasing levels of rumen-degradable starch (RDS) were included in this study, and SARA goats fed 70% concentrate diets supplemented with whole corn (HGW-SARA) and SARA goats fed 70% concentrate diets supplemented with crushed corn (HGC-SARA) were identified. Moreover, 11 goats fed a control basal diet, named LGW-CON, were also included. Compared with those in the LGW-CON group, the rumen fermentation capacity was enhanced, accompanied by ruminal epithelial and systemic inflammation, in goats from HGW-SARA and HGC-SARA. Between them, HGC-SARA goats presented less inflammation. Notably, the ruminal inflammation-related pathways were increased only in the HGW-SARA group but not in the HGC-SARA group. Metagenomic analysis revealed that the β diversity of SARA goats was significantly different from that of LGW-CON goats. Ruminococcus significantly increased in both SARA groups, whereas Prevotella and Bacteroidales significantly decreased, which was accompanied by a decrease in cellulose and hemicellulose enzymes and an increase in lysozymes and lipopolysaccharide synthesis enzymes. Multi-omics analysis of the ruminal contents and tissues suggested that epithelial inflammation was caused by disturbed ruminal microbiome-induced Th17 cell differentiation and IL-17 signalling pathway activation. Comparative analyses between the HGW-SARA and HGC-SARA groups highlighted the importance of Selenomonas and Bifidobacterium, as well as bacterial tryptophan metabolism, in the production of 3-indoleacetic acid, which mitigated ruminal epithelial inflammation by modulating Th17 cells and inhibiting IL-17 signalling. Ruminal microbiota transplantation from HGW-SARA goats to healthy dairy goats and mice revealed the role of microbes in epithelial inflammation. Additionally, 3-indoleacetic acid supplementation reduced rumen inflammation and the IL-17 concentration in the serum, improved VFAs absorption, and enhanced milk production. CONCLUSIONS: This study unveiled that after SARA was induced by high-concentrate feeding, the rumen homeostasis was disrupted, and rumen fiber degradation capacity of dairy goats decreased, but the LPS synthesis capacity increased, and inflammation of the rumen epithelium was observed. However, the ruminal microbial species from the Bifidobacterium and Selenomonas genera and bacterial 3-indole acetic acid are pivotal in mitigating ruminal epithelial inflammation during SARA in dairy goats. This could potentially be attributed to the modulation of ruminal Th17 cell proportions and the inhibition of IL-17 signalling pathways. Video Abstract.

Rumen↗
PubMed1967

Auxin Transport in Zea mays Coleoptiles II. Influence of Light on the Transport of Indoleacetic Acid-2-C.

The effect of bilateral irradiation with white light (1000 Meter Candle Sec) on the basipetal transport of auxin has been investigated. Illumination of either the intact shoot or the excised coleoptile tip of the Zea seedling, decreased the amount of diffusible auxin obtained from the tip, and decreased Avena curvature response to unilaterally applied indoleacetic acid. Irradiation of the intact Zea seedling did not affect the absorption of (14)C-labeled indoleacetic acid from an agar block subsequently placed on the decapitated coleoptile. However, light caused a significant decrease in the amount of labeled auxin basipetally transported, without affecting materially the velocity of that transport. These and other observations are interpreted as support for the hypothesis that the primary hormonal phenomenon in first-positive phototropism is a light-induced impairment in the basipetal transport of auxin.

Journal Article↗
PubMed1974

Cell wall and protoplast isoperoxidases in relation to injury, indoleacetic Acid, and ethylene effects.

In tobacco (Nicotiana Tabacum) pith, sweet potato (Ipomoea batatas), and carrot (Daucus carota) storage roots, differences were found between cell wall and protoplast peroxidases in their isoenzyme patterns, activity, and reaction to tissue injury.In the pith of elongating tobacco internodes, 90% of total activity was associated with the walls, 80% of which was due to the ionically and covalently bound fractions. With senescence, the increase in activity occurred mainly in the protoplast and the free fraction in the walls. The major protoplast isoperoxidases formed the free wall fraction, and the minor ones formed the wall bound fractions. The minor isoperoxidases were the only ones whose activities were affected by cut injury. Neither senescence nor injury caused qualitative changes in the cell isoperoxidase pattern. In the potato root cells, the isoperoxidases were also distinctive in their distribution and in their reactions to injury as well as to ethylene.In potato and carrot roots, the wall fractions contributed 30 and 95%, respectively, to total peroxidase activity. The injury-induced increase in peroxidase activity occurred mainly in the protoplast of tobacco pith and potato roots and almost entirely in the ionically bound fraction of the walls in carrot roots. Ethylene stimulated peroxidase development in potato roots, especially in the protoplast, but had no effect in either tobacco pith or carrot roots. Ethylene did not affect the inhibiting action of indoleacetic acid on peroxidase activity in tobacco pith, nor did indoleacetic acid significantly affect the stimulating action of ethylene in potato roots.Actinomycin D inhibited the injury-dependent development of peroxidase in tobacco pith, stimulated the injury- and ethylene-dependent peroxidase development in potato root, and had no effect on peroxidase development in carrot root. Cycloheximide prevented the increase in peroxidase activity in tobacco pith and potato root, but not in the carrot root. Thus, the enhancement of peroxidase activity resulted from either enzyme activation exclusively or from enzyme synthesis. RNA synthesis seems to be only indirectly related to isoperoxidase synthesis caused by injury or ethylene.

Journal Article↗
PubMed1979

Production and action of ethylene in senescing leaf discs: effect of indoleacetic Acid, kinetin, silver ion, and carbon dioxide.

Supraoptimal concentrations of indoleacetic acid (IAA) stimulated ethylene production, which in turn appeared to oppose the senescence-retarding effect of IAA in tobacco leaf discs. Kinetin acted synergistically with IAA in stimulating ethylene production, but it inhibited senescence. Silver ion and CO(2), which are believed to block ethylene binding to its receptor sites, delayed senescence in terms of chlorophyll loss and stimulated ethylene production. Both effects of Ag(+) were considerably greater than those of CO(2). IAA, kinetin, CO(2), and Ag(+), combined, acted to increase ethylene production further. Although this combination increased ethylene production about 160-fold over that of the control, it inhibited senescence. Treatment with 25 mul/l of ethylene in the presence of IAA enhanced chlorophyll loss in leaf discs and inhibited by about 90% the conversion of l-[3,4-(14)C] methionine to (14)C(2)H(4) suggesting autoinhibition of ethylene production.The results suggest that ethylene biosynthesis in leaves is controlled by hormones, especially auxin, and possibly the rate of ethylene production depends, via a feedback control system, on the rates of ethylene binding at its receptor sites.

Journal Article↗
PubMedDate not supplied

Effect of beta-indoleacetic acid on RNA and protein synthesis in Escherichia coli.

The effect of different concentrations of beta-indoleacetic acid (IAA) on RNA and protein synthesis and the stability of associations of E. coli ribosomes at 3 mM Mg2+ was investigated. IAA in a concentration of 100 microgram/ml had a slight stimulatory effect on the incorporation of [14C]leucine into proteins and stimulated the incorporation of [14C]uracil into the RNA of intact cells more noticeably. In the presence of 2500 microgram/ml of the auxin RNA synthesis was inhibited by 65% and protein synthesis by 40-50% as compared to the control. In a cell-free system containing poly(U) IAA in concentrations of 10-100 microgram/ml increased polyphenylalanine synthesis by an average of 30%, while at high concentrations IAA noticeably inhibited its synthesis. It was found that the proportion of stable ribosomes in lysates obtained from cells incubated with IAA in concentrations of 250 and 1000 microgram/ml decreased to 18 and 3%. It is suggested that the inhibition of protein synthesis in E. coli by IAA is due to inhibition of the initiation of translation.

Bacterial Proteins↗
PubMed1973

Rhythmic Differences in the Basipetal Movement of Indoleacetic Acid between Separated Upper and Lower Halves of Geotropically Stimulated Corn Coleoptiles.

Rhythmic fluctuation in the basipetal movement of auxin occurs in corn (Zea mays) coleoptiles oriented either in the vertical or in the horizontal position. This periodicity of transport rate varies from region to region in a horizontal coleoptile. Between an upper and lower half coleoptile (with respect to gravity), the comparable regions in the coleoptile do not exhibit similar periods. The velocity of transport also varies from region to region along a geostimulated coleoptile. In the upper half coleoptile, the velocities are 29 millimeters per hour (tip), 8 millimeters per hour (mid), and 30 millimeters per hour (base); in the lower, 41 millimeters per hour (tip), 12 millimeters per hour (mid) and 12 millimeters per hour (base).During the first 24 minutes of transport, there is a reduction of basipetal movement of (14)C-indoleacetic acid in the lower half coleoptile. This may be causally related to the initial downward geotropic curvature in oat and corn coleoptiles reported by others. However, about 30 minutes after donor removal a significant reduction of basipetal transport of indoleacetic acid occurs in the upper half coleoptiles.

Journal Article↗
PubMed1991

Red light-regulated growth. I. Changes in the abundance of indoleacetic acid and a 22-kilodalton auxin-binding protein in the maize mesocotyl.

We examined the changes in the levels of indoleacetic acid (IAA), IAA esters, and a 22-kilodalton subunit auxin-binding protein (ABP1) in apical mesocotyl tissue of maize (Zea mays L.) during continuous red light (R) irradiation. These changes were compared with the kinetics of R-induced growth inhibition in the same tissue. Upon the onset of continuous irradiation, growth decreased in a continuous manner following a brief lag period. The decrease in growth continued for 5 hours, then remained constant at 25% of the dark rate. The abundance of ABP1 and the level of free IAA both decreased in the mesocotyl. Only the kinetics of the decrease in IAA within the apical mesocotyl correlated with the initial change in growth, although growth continued to decrease even after IAA content reached its final level, 50% of the dark control. This decrease in IAA within the mesocotyl probably occurs primarily by a change in its transport within the shoot since auxin applied as a pulse move basipetally in R-irradiated tissue at the same rate but with half the area as dark control tissue. In situ localization of auxin in etiolated maize shoots revealed that R-irradiated shoots contained less auxin in the epidermis than the dark controls. Irradiated mesocotyl grew 50% less than the dark controls even when incubated in an optimal level of auxin. However, irradiated and dark tissue contained essentially the same amount of radioactivity after incubation in [14C]IAA indicating that the light treatment does not affect the uptake into the tissue through the cut end, although it is possible that a small subset of cells within the mesocotyl is affected. These observations support the hypothesis that R causes a decrease in the level of auxin in epidermal cells of the mesocotyl, consequently constraining the growth of the entire mesocotyl.

Biological Transport↗
PubMed2001

Relationship between production of 3-indoleacetic acid and peroxidase-laccase activities depending on the culture periods in Funalia trogii (Trametes trogii).

The relationship between production of 3-indoleacetic acid (IAA) and peroxidase and laccase activity was investigated in white-rot fungus Funalia trogii (Trametes trogii). F. trogii produced IAA and peroxidase and laccase as both primary metabolite and secondary metabolite; the levels of IAA may be influenced by peroxidase and laccase. A correlation exists between the levels of IAA and peroxidase-laccase activity.

Indoleacetic Acids↗
PubMed1973

Comparative studies on tobacco pith and sweet potato root isoperoxidases in relation to injury, indoleacetic Acid, and ethylene effects.

Sweet potato (Ipomoea batatas) root parenchyma and tobacco (Nicotiana tabacum) stem pith, both known to increase peroxidase activity after excision, differed from each other in their isoperoxidase patterns and in the isoperoxidase responses to injury and exogenous ethylene.In potato root sections, the injury-dependent peroxidase increase was due to an induction of two isoenzymes, as well as to a promotion of some constitutive ones. In tobacco pith, this increase was entirely due to seven isoperoxidases not detectable, or detectable only in traces, immediately after excision. Actinomycin D did not inhibit the development of any isoperoxidases in the potato root sections and strongly repressed the development of all injury-induced isoenzymes in tobacco pith. Cycloheximide totally inhibited the development of all isoperoxidases in both species, with the exception of two injury-enhanced isoenzymes in root parenchyma.In root sections, indoleacetic acid had a weak inhibitory effect on one injury-induced isoperoxidase only, whereas in tobacco pith it inhibited the development of the injury-induced, as well as the constitutive, isoperoxidases.Exogenous ethylene did not induce, enhance, or significantly suppress any of the tobacco pith isoenzymes, whereas in potato root sections, it suppressed slightly the development of the injury-induced, had no effect on some of the injury-enhanced, and greatly promoted some of the injury-unaffected or-enhanced isoperoxidases. Removal of ethylene stopped the ethylene-dependent peroxidase increase without affecting the injury-induced increase. When applied to intact potato roots, ethylene did not induce any new isoperoxidases and promoted the same constitutive isoenzymes as it did in root sections.Thus, the tissue peroxidase response to ethylene seems independent of its response to injury. Differences between tissue species in their response to ethylene may depend on the presence or absence of isoperoxidases sensitive to ethylene. The inhibition of injury-dependent peroxidase development by indoleacetic acid cannot be explained by an ethylene-induced inhibition.

Journal Article↗
PubMed1991

Influence of 3-indoleacetic acid on cytochemical changes in nuclei and cytoplasm of human fibroblasts in the cell culture.

The performed studies covered the action of 3-indoleacetic acid (3IAA) on human fibroblasts cultured in vitro. The 3IAA implemented in the studies was provided by Chemapol Firm (Czechoslovakia). All the investigations were carried out on I passage fibroblasts, taken from the human skin in form of monolayer culture. Feulgen's method and autographic one were resorted to in the studies. The optimal time of acid hydrolysis was 10 min. Quantitative measurements of DNA in nuclei of fibroblasts were done on integrating cytophotometer. Incubation with labelled 3H uridine as RNA precursor was employed for demonstrating the activity of cell nucleus transcription. As concerns the quantitative changes in nucleic acids, it was disclosed that DNA and RNA synthesis was intensified. Nuclei were seen to appear with polydiploidal DNA amount in cultures being influenced by 3IAA action. The smallest number of mitoses was revealed in the cultures exposed to the action of the highest dose of the said compound. Stronger 3H uridine incorporation was recorded in cultures 24 and 72 hours after the administration of 10 mg/1000 ml of 3IAA. The results were presented in the form of diagrams, nucleinogram and tables.

Adult↗
PubMed1990

Assay for the enzymatic conversion of indoleacetic acid to 3-methylindole in a ruminal Lactobacillus species.

An assay to measure the rate of enzymatic formation of 3-methylindole (3MI) from indoleacetic acid (IAA) in Lactobacillus sp. strain 11201 was developed. The reaction mixture contained 50 micrograms of microbial protein per ml (range, 25 to 100 mg/ml), essential low-molecular-weight reaction ingredients, and radiolabeled IAA as substrate (range, 0 to 2 mM IAA). The reaction was anaerobic for 25 min at 39 degrees C. The apparent Michaelis-Menten constants were: Km, 0.14 mM IAA; and Vmax, 64 nmol 3MI.mg-1.min-1. The inhibitors avidin, aminopterin, and EDTA had no effect on the 3MI-forming enzyme. Dithionite stimulated the 3MI-forming enzyme. The product of the reaction, 3MI, acted as a noncompetitive inhibitor of the enzyme. Enzyme activity was associated with the cell wall fraction after sonication; treatment with the French press; or treatment with detergents, proteolytic enzymes, and EDTA.

Animals↗
PubMed2001

Heterogeneous transcription of an indoleacetic acid biosynthetic gene in Erwinia herbicola on plant surfaces.

We investigated the spatial pattern of expression of ipdC, a plant inducible gene involved in indoleacetic acid biosynthesis in Erwinia herbicola, among individual cells on plants to gain a better understanding of the role of this phenotype in the epiphytic ecology of bacteria and the factors involved in the regulation of ipdC. Nonpathogenic E. herbicola strain 299R harboring a transcriptional fusion of ipdC to gfp was inoculated onto bean plants, recovered from individual leaves 48 h after inoculation, and subjected to fluorescence in situ hybridization using a 16S rRNA oligonucleotide probe specific to strain 299R. Epifluorescence images captured through a rhodamine filter were used to distinguish the 5carboxytetramethylrhodamine-labeled cells of strain 299R from other leaf microflora. Quantification of the green fluorescence intensity of individual cells by analysis of digital images revealed that about 65% of the 299R cells recovered from bean leaves had higher ipdC expression than in culture. Additionally, 10% of the cells exhibited much higher levels of green fluorescence than the median fluorescence intensity, indicating that they are more heterogeneous with respect to ipdC expression on plants than in culture. Examination of 299R cells in situ on leaf surfaces by confocal laser scanning microscopy after fluorescence in situ hybridization of cells on leaf samples showed that even cells that were in close proximity exhibited dramatically different green fluorescence intensities, and thus, were in a physical or chemical microenvironment that induced differential expression of ipdC.

Carboxy-Lyases↗
PubMed1972

Changes in indoleacetic Acid oxidase isoenzymes in tobacco tissues after treatment with 2,4-dichlorophenoxyacetic Acid.

2,4-Dichlorophenoxyacetic acid had a multiple effect on the development of indoleacetic acid oxidase isoenzymes in tobacco callus tissues (Nicotiana tabacum, cv. White Gold) cultured in vitro, and the development of these isoenzymes was differentially associated with growth promotion or inhibition depending on the concentration of 2,4-dichlorophenoxyacetic acid. At low concentrations (0.1 to 1 mum) it promoted the development of a fast migrating isoenzyme A(5) accompanied by stimulation of a tumor-type growth. At high concentrations (10 to 100 mum), it inhibited the development of the fast migrating isoenzymes but promoted a sharp rise in others with slower electrophoretic mobilities, which was accompanied by growth inhibition. The implications are that 2,4-dichlorophenoxyacetic acid might alter the level of endogenous auxins through its dual effects on the oxidase isoenzyme system.

Journal Article↗
PubMed1977

Indoleacetic Acid Levels in Phaseolus, Zea, and Pincus during Seed Germination.

The content of indoleacetic acid (IAA) was determined in dry and germinating seeds of French bean (Phaseolus vulgaris), sugar maize (Zea mays), and Scots pine (Pinus silvestris). IAA was found in both the dry and the soaked seeds of the three species examined. The amount of IAA per gram fresh weight was extremely different in the three species whereas the variation between different harvests of the same species was small. Maize contained the highest level of IAA and bean the smallest. The time of imbibition was of decisive importance for the level of IAA. In all three species the content of IAA increased considerably during the initial 4 hours of swelling. The highest level of IAA was found in seeds that had swelled for 24 to 48 hours, during which period the radicles began to emerge from the seed coat. Later, during the period of rapid root growth, the content of IAA declined.

Journal Article↗