Indoleacetic Acids
Skatole
Hydroxyindoleacetic Acid
Plant Growth Regulators
Tryptophan Hydroxylase
Pseudomonas
Tryptophan
The auxin-insensitive bodenlos mutation affects primary root formation and apical-basal patterning in the Arabidopsis embryo. (1/2030)
In Arabidopsis embryogenesis, the primary root meristem originates from descendants of both the apical and the basal daughter cell of the zygote. We have isolated a mutant of a new gene named BODENLOS (BDL) in which the primary root meristem is not formed whereas post-embryonic roots develop and bdl seedlings give rise to fertile adult plants. Some bdl seedlings lacked not only the root but also the hypocotyl, thus resembling monopteros (mp) seedlings. In addition, bdl seedlings were insensitive to the auxin analogue 2,4-D, as determined by comparison with auxin resistant1 (axr1) seedlings. bdl embryos deviated from normal development as early as the two-cell stage at which the apical daughter cell of the zygote had divided horizontally instead of vertically. Subsequently, the uppermost derivative of the basal daughter cell, which is normally destined to become the hypophysis, divided abnormally and failed to generate the quiescent centre of the root meristem and the central root cap. We also analysed double mutants. bdl mp embryos closely resembled the two single mutants, bdl and mp, at early stages, while bdl mp seedlings essentially consisted of hypocotyl but did form primary leaves. bdl axr1 embryos approached the mp phenotype at later stages, and bdl axr1 seedlings resembled mp seedlings. Our results suggest that BDL is involved in auxin-mediated processes of apical-basal patterning in the Arabidopsis embryo. (+info)The DNA binding site of the Dof protein NtBBF1 is essential for tissue-specific and auxin-regulated expression of the rolB oncogene in plants. (2/2030)
The Dof proteins are a large family of plant transcription factors that share a single highly conserved zinc finger. The tobacco Dof protein NtBBF1 was identified by its ability to bind to regulatory domain B in the promoter of the rolB oncogene. In this study, we show that the ACT T TA target sequence of NtBBF1 in domain B is necessary for tissue-specific expression of rolB. beta-Glucuronidase (GUS) activity of tobacco plants containing a rolB promoter-GUS fusion with a mutated NtBBF1 target sequence within domain B is almost completely suppressed in apical meristems and is severely abated in the vascular system. The ACT T TA motif is shown here also to be one of the cis-regulatory elements involved in auxin induction of rolB. The pattern of NtBBF1 expression in plants is remarkably similar to that of rolB, except in mesophyll cells of mature leaves, in which only NtBBF1 expression could be detected. Ectopic expression of rolB in mesophyll cells was achieved by particle gun delivery if the NtBBF1 binding sequence was intact. These data provide evidence that in the plant, a Dof protein DNA binding sequence acts as a transcriptional regulatory motif, and they point to NtBBF1 as the protein involved in mediating tissue-specific and auxin-inducible expression of rolB. (+info)IAR3 encodes an auxin conjugate hydrolase from Arabidopsis. (3/2030)
Amide-linked conjugates of indole-3-acetic acid (IAA) are putative storage or inactivation forms of the growth hormone auxin. Here, we describe the Arabidopsis iar3 mutant that displays reduced sensitivity to IAA-Ala. IAR3 is a member of a family of Arabidopsis genes related to the previously isolated ILR1 gene, which encodes an IAA-amino acid hydrolase selective for IAA-Leu and IAA-Phe. IAR3 and the very similar ILL5 gene are closely linked on chromosome 1 and comprise a subfamily of the six Arabidopsis IAA-conjugate hydrolases. The purified IAR3 enzyme hydrolyzes IAA-Ala in vitro. iar 3 ilr1 double mutants are more resistant than either single mutant to IAA-amino acid conjugates, and plants overexpressing IAR3 or ILR1 are more sensitive than is the wild type to certain IAA-amino acid conjugates, reflecting the overlapping substrate specificities of the corresponding enzymes. The IAR3 gene is expressed most strongly in roots, stems, and flowers, suggesting roles for IAA-conjugate hydrolysis in those tissues. (+info)Biosynthesis of indole-3-acetic acid in Azospirillum brasilense. Insights from quantum chemistry. (4/2030)
Quantum chemical methods AM1 and PM3 and chromatographic methods were used to qualitatively characterize pathways of bacterial production of indole-3-acetic acid (IAA). The standard free energy changes (delta G(o)'sum) for the synthesis of tryptophan (Trp) from chorismic acid via anthranilic acid and indole were calculated, as were those for several possible pathways for the synthesis of IAA from Trp, namely via indole-3-acetamide (IAM), indole-3-pyruvic acid (IPyA), and indole-3-acetonitrile (IAN). The delta G(o)'sum for Trp synthesis from chorismic acid was -402 (-434) kJ.mol-1 (values in parentheses were calculated by PM3). The delta G(o)'sum for IAA synthesis from Trp were -565 (-548) kJ.mol-1 for the IAN pathway, -481 (-506) kJ.mol-1 for the IAM pathway, and -289 (-306) kJ.mol-1 for the IPyA pathway. By HPLC analysis, the possibility was assessed that indole, anthranilic acid, and Trp might be utilized as precursors for IAA synthesis by Azospirillum brasilense strain Sp 245. The results indicate that there is a high motive force for Trp synthesis from chorismic acid and for IAA synthesis from Trp, and make it unlikely that anthranilic acid and indole act as the precursors to IAA in a Trp-independent pathway. (+info)Reconstitution of an electrogenic auxin transport activity mediated by Arabidopsis thaliana plasma membrane proteins. (5/2030)
Plasma membrane proteins from Arabidopsis thaliana leaves were reconstituted into proteoliposomes and a K+ diffusion potential was generated. The resulting ionic fluxes, determined in the presence of the plant hormone auxin (indole-3 acetic acid), showed an additional electrogenic and saturable component, with a K(M) of 6 microM. This flux was neither detected in liposomes in the presence of indole-3 acetic acid, nor in proteoliposomes in the presence of an inactive auxin analog and was completely inhibited by 3 microM naphtylphthalamic acid, a specific inhibitor of the auxin efflux carrier. The efficiency of the reconstituted carrier and the mechanism of its regulation by naphtylphthalamic acid are discussed. (+info)Novel gating mechanism of polyamine block in the strong inward rectifier K channel Kir2.1. (6/2030)
Inward rectifying K channels are essential for maintaining resting membrane potential and regulating excitability in many cell types. Previous studies have attributed the rectification properties of strong inward rectifiers such as Kir2.1 to voltage-dependent binding of intracellular polyamines or Mg to the pore (direct open channel block), thereby preventing outward passage of K ions. We have studied interactions between polyamines and the polyamine toxins philanthotoxin and argiotoxin on inward rectification in Kir2.1. We present evidence that high affinity polyamine block is not consistent with direct open channel block, but instead involves polyamines binding to another region of the channel (intrinsic gate) to form a blocking complex that occludes the pore. This interaction defines a novel mechanism of ion channel closure. (+info)Glutamate receptor expression regulates quantal size and quantal content at the Drosophila neuromuscular junction. (7/2030)
At the Drosophila glutamatergic neuromuscular junction, the postsynaptic cell can regulate synaptic strength by both changing its sensitivity to neurotransmitter and generating a retrograde signal that regulates presynaptic transmitter release. To investigate the molecular mechanisms underlying these forms of plasticity, we have undertaken a genetic analysis of two postsynaptic glutamate receptors that are expressed at this synapse. Deletion of both genes results in embryonic lethality that can be rescued by transgenic expression of either receptor. Although these receptors are redundant for viability, they have important differences. By transgenically rescuing the double mutant, we have investigated the relationship of receptor gene dosage and composition to synaptic function. We find that the receptor subunit composition regulates quantal size, Argiotoxin sensitivity, and receptor desensitization kinetics. Finally, we show that the activity of the receptor can regulate the retrograde signal functioning at this synapse. Thus, the diversity of receptors expressed at this synapse provides the cell with mechanisms for generating synaptic plasticity. (+info)AUX1 regulates root gravitropism in Arabidopsis by facilitating auxin uptake within root apical tissues. (8/2030)
Plants employ a specialized transport system composed of separate influx and efflux carriers to mobilize the plant hormone auxin between its site(s) of synthesis and action. Mutations within the permease-like AUX1 protein significantly reduce the rate of carrier-mediated auxin uptake within Arabidopsis roots, conferring an agravitropic phenotype. We are able to bypass the defect within auxin uptake and restore the gravitropic root phenotype of aux1 by growing mutant seedlings in the presence of the membrane-permeable synthetic auxin, 1-naphthaleneacetic acid. We illustrate that AUX1 expression overlaps that previously described for the auxin efflux carrier, AtPIN2, using transgenic lines expressing an AUX1 promoter::uidA (GUS) gene. Finally, we demonstrate that AUX1 regulates gravitropic curvature by acting in unison with the auxin efflux carrier to co-ordinate the localized redistribution of auxin within the Arabidopsis root apex. Our results provide the first example of a developmental role for the auxin influx carrier within higher plants and supply new insight into the molecular basis of gravitropic signalling. (+info)Indole-3-acetic acid (IAA) is not exactly a medical term, but rather a scientific term used in the field of biochemistry and physiology. It is a type of auxin, which is a plant hormone that regulates various growth and development processes in plants. IAA is the most abundant and best-studied natural auxin.
Medically, indole-3-acetic acid may be mentioned in the context of certain medical conditions or treatments related to plants or plant-derived substances. For example, some research has investigated the potential use of IAA in promoting wound healing in plants or in agricultural applications. However, it is not a substance that is typically used in medical treatment for humans or animals.
Skatole is a medical term that refers to a chemical compound with the formula C9H9NO2. It is a crystalline substance with an extremely foul odor, resembling that of feces. Skatole is produced in the body as a byproduct of bacterial breakdown of tryptophan, an essential amino acid, in the intestines. Normally, skatole is excreted in the feces and does not cause any problems.
However, when there is an overgrowth of bacteria in the intestines or a problem with the normal flow of bile, which helps to eliminate skatole from the body, skatole can accumulate in the bloodstream and tissues. This can lead to a condition called "skatole poisoning," which can cause symptoms such as nausea, vomiting, abdominal pain, and neurological problems.
Skatole is also used in perfumes and other fragrances to create a fecal or animalistic odor, although it is typically used in very small amounts due to its strong smell.
Hydroxyindoleacetic acid (5HIAA) is a major metabolite of the neurotransmitter serotonin, formed in the body through the enzymatic degradation of serotonin by monoamine oxidase and aldehyde dehydrogenase. 5HIAA is primarily excreted in the urine and its measurement can be used as a biomarker for serotonin synthesis and metabolism in the body.
Increased levels of 5HIAA in the cerebrospinal fluid or urine may indicate conditions associated with excessive serotonin production, such as carcinoid syndrome, while decreased levels may be seen in certain neurodegenerative disorders, such as Parkinson's disease. Therefore, measuring 5HIAA levels can have diagnostic and therapeutic implications for these conditions.
Tryptamines are a class of organic compounds that contain a tryptamine skeleton, which is a combination of an indole ring and a ethylamine side chain. They are commonly found in nature and can be synthesized in the lab. Some tryptamines have psychedelic properties and are used as recreational drugs, such as dimethyltryptamine (DMT) and psilocybin. Others have important roles in the human body, such as serotonin, which is a neurotransmitter that regulates mood, appetite, and sleep. Tryptamines can also be found in some plants and animals, including certain species of mushrooms, toads, and catnip.
Plant growth regulators (PGRs) are natural or synthetic chemical substances that, when present in low concentrations, can influence various physiological and biochemical processes in plants. These processes include cell division, elongation, and differentiation; flowering and fruiting; leaf senescence; and stress responses. PGRs can be classified into several categories based on their mode of action and chemical structure, including auxins, gibberellins, cytokinins, abscisic acid, ethylene, and others. They are widely used in agriculture to improve crop yield and quality, regulate plant growth and development, and enhance stress tolerance.
Tryptophan hydroxylase is an enzyme that plays a crucial role in the synthesis of neurotransmitters and hormones, including serotonin and melatonin. It catalyzes the conversion of the essential amino acid tryptophan to 5-hydroxytryptophan (5-HTP), which is then further converted to serotonin. This enzyme exists in two isoforms, TPH1 and TPH2, with TPH1 primarily located in peripheral tissues and TPH2 mainly found in the brain. The regulation of tryptophan hydroxylase activity has significant implications for mood, appetite, sleep, and pain perception.
"Pseudomonas" is a genus of Gram-negative, rod-shaped bacteria that are widely found in soil, water, and plants. Some species of Pseudomonas can cause disease in animals and humans, with P. aeruginosa being the most clinically relevant as it's an opportunistic pathogen capable of causing various types of infections, particularly in individuals with weakened immune systems.
P. aeruginosa is known for its remarkable ability to resist many antibiotics and disinfectants, making infections caused by this bacterium difficult to treat. It can cause a range of healthcare-associated infections, such as pneumonia, bloodstream infections, urinary tract infections, and surgical site infections. In addition, it can also cause external ear infections and eye infections.
Prompt identification and appropriate antimicrobial therapy are crucial for managing Pseudomonas infections, although the increasing antibiotic resistance poses a significant challenge in treatment.
Tryptophan is an essential amino acid, meaning it cannot be synthesized by the human body and must be obtained through dietary sources. Its chemical formula is C11H12N2O2. Tryptophan plays a crucial role in various biological processes as it serves as a precursor to several important molecules, including serotonin, melatonin, and niacin (vitamin B3). Serotonin is a neurotransmitter involved in mood regulation, appetite control, and sleep-wake cycles, while melatonin is a hormone that regulates sleep-wake patterns. Niacin is essential for energy production and DNA repair.
Foods rich in tryptophan include turkey, chicken, fish, eggs, cheese, milk, nuts, seeds, and whole grains. In some cases, tryptophan supplementation may be recommended to help manage conditions related to serotonin imbalances, such as depression or insomnia, but this should only be done under the guidance of a healthcare professional due to potential side effects and interactions with other medications.
A plant root is not a medical term per se, but it is a term from botany, which is the study of plants. However, I can certainly provide a definition for you.
Plant roots are the underground organs of a plant that typically grow downward into the soil. They serve several important functions, including:
1. Anchorage: Roots help to stabilize the plant and keep it upright in the ground.
2. Absorption: Roots absorb water and nutrients from the soil, which are essential for the plant's growth and development.
3. Conduction: Roots conduct water and nutrients up to the above-ground parts of the plant, such as the stem and leaves.
4. Vegetative reproduction: Some plants can reproduce vegetatively through their roots, producing new plants from root fragments or specialized structures called rhizomes or tubers.
Roots are composed of several different tissues, including the epidermis, cortex, endodermis, and vascular tissue. The epidermis is the outermost layer of the root, which secretes a waxy substance called suberin that helps to prevent water loss. The cortex is the middle layer of the root, which contains cells that store carbohydrates and other nutrients. The endodermis is a thin layer of cells that surrounds the vascular tissue and regulates the movement of water and solutes into and out of the root. The vascular tissue consists of xylem and phloem, which transport water and nutrients throughout the plant.