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PubMed1998

Evolution, mutations, and human longevity: European royal and noble families.

The evolutionary theory of aging predicts that the equilibrium gene frequency for deleterious mutations should increase with age at onset of mutation action because of weaker (postponed) selection against later-acting mutations. According to this mutation accumulation hypothesis, one would expect the genetic variability for survival (additive genetic variance) to increase with age. The ratio of additive genetic variance to the observed phenotypic variance (the heritability of longevity) can be estimated most reliably as the doubled slope of the regression line for offspring life span on paternal age at death. Thus, if longevity is indeed determined by late-acting deleterious mutations, one would expect this slope to become steeper at higher paternal ages. To test this prediction of evolutionary theory of aging, we computerized and analyzed the most reliable and accurate genealogical data on longevity in European royal and noble families. Offspring longevity for each sex (8409 records for males and 3741 records for females) was considered as a dependent variable in the multiple regression model and as a function of three independent predictors: paternal age at death (for estimation of heritability of life span), paternal age at reproduction (control for parental age effects), and cohort life expectancy (control for cohort and secular trends and fluctuations). We found that the regression slope for offspring longevity as a function of paternal longevity increases with paternal longevity, as predicted by the evolutionary theory of aging and by the mutation accumulation hypothesis in particular.

Adult↗
PubMed1999

Subunit mutations affect ethanol actions on GABA(A) receptors expressed in Xenopus oocytes.

1. Mutations of specific amino acids were introduced in transmembrane domains (TM) of GABA(A) receptor alpha2, beta1 and gamma2L subunits. The effects of these mutations on the action of ethanol were studied using the Xenopus oocyte expression system and two-electrode voltage-clamp recording techniques. 2. Mutant alpha2 subunits containing S270I (TM2) or A291W (TM3) made the receptor more sensitive to GABA, as compared to wild-type alpha2beta1gamma2L receptor. The mutation S265I (TM2) of beta1 and S280I (TM2) or S30IW (TM3) in gamma2L subunits did not alter apparent affinity of the receptor for GABA. M286W (TM3) in the beta1 subunit resulted in a receptor that was tonically open. 3. Using an EC5 concentration of GABA, the function of the wild-type receptor with alpha2beta1gamma2L subunits was potentiated by ethanol (50-200 mM). The mutations in TM2 or TM3 of the alpha2 subunit diminished the potentiation by ethanol. The action of ethanol was also eliminated with a mutation in the TM2 site of the beta1 subunit. Ethanol produced significant inhibition of GABA responses in receptors containing the combination of alpha2 and beta1 TM2 mutants with a wild-type gamma2L subunit. A small but significant reduction in the potentiation by ethanol was observed with gamma2L TM2 and/or TM3 mutants. 4. From these results, we suggest that in heteromeric GABA(A) receptors composed of the alpha, beta and gamma subunits, ethanol may bind in a cavity formed by TM2 and TM3, and that binding to the alpha or beta subunit may be more critical than the gamma subunit.

Amino Acid Sequence↗
PubMed1988

Mutation of the insulin receptor at tyrosine 960 inhibits signal transmission but does not affect its tyrosine kinase activity.

Tyrosyl phosphorylation is implicated in the mechanism of insulin action. Mutation of the beta-subunit of the insulin receptor by substitution of tyrosyl residue 960 with phenylalanine had no effect on insulin-stimulated autophosphorylation or phosphotransferase activity of the purified receptor. However, unlike the normal receptor, this mutant was not biologically active in Chinese hamster ovary cells. Furthermore, insulin-stimulated tyrosyl phosphorylation of at least one endogenous substrate (pp185) was increased significantly in cells expressing the normal receptor but was barely detected in cells expressing the mutant. Therefore, beta-subunit autophosphorylation was not sufficient for the insulin response, and a region of the insulin receptor around Tyr-960 may facilitate phosphorylation of cellular substrates required for transmission of the insulin signal.

Amino Acid Sequence↗
PubMed1974

New class of streptomycin-resistant mutants incompatible with supX suppressor mutations in Salmonella typhimurium.

Streptomycin-resistant colonies of Salmonella typhimurium appearing in platings of supX suppressors of strain leu-500 are less variegated in size than are those derived from strain leu-500 counterparts. Several of the streptomycin-resistant leu-500 clones, furthermore, yield suppressors and revertants of the leu-500 auxotrophy at unusually low rates, suggesting that they provide a genetic background inimicable to supX suppression. Two such "suppression-restrictive" leu-500 streptomycin-resistant (str) mutants, designated strains M(1) and M(4), were characterized as to their ability to receive the trp-supX-cysB linkage region by transduction. Coentry of a donor supX deletion mutation with the selected trp(+) marker was not observed even though these sites display more than 10% linkage in control experiments. This was demonstrably the result of nonviability of the combined supX mutant, M(1) or M(4) streptomycin-resistant genotype, rather than the lack of suppression of the leu-500 imparted auxotrophy. Both M(1)- and M(4)-type resistance was accompanied by pleiotropic effects resembling those caused by strB (nonribosomal)- rather than strA (ribosomal)-type resistance, but both restrictive mutants had a high upper limit of resistance corresponding to that of strA-type mutants. Transduction analyses indicated that the str character of neither the M(1) nor the M(4) strain was linked to the strA or the strB gene. These mutations define a previously undescribed locus, which we propose to designate strC, apparently related to streptomycin uptake rather than its intracellular action. Mutation at this locus is evidently incompatible with the inactivation or removal of the supX site, suggesting a functional association between products of the genes.

Chromosome Mapping↗
PubMedDate not supplied

[Effect of tryptophan and its metabolites on the conditioned reflex activity of the honeybee].

The effect of tryptophane and its derivatives on the rate of elaboration and transformation of conditioned reflexes (CR) to odour, with alimentary reinforcement, was studied in wild bees under two conditions: free movement of the bee or its immobilization (stress situation), by means of genetic models (mutations, successive blocking stages of kynurenin path of tryptophane metabolism). It was shown that mutations eliciting accumulation of free tryptophane and serotonin in the hemolymph of the bees and creating a deficit of kynurenins accelerate the transformation of conditioned reflexes and aggravate the depression of conditioned activity usually elicited in wild bees by monotonous prolonged presentation of conditioned signal. The injections of tryptophane and serotonin (5 mg) produce the same action. Mutations, eliciting accumulation in the hemolymph of the kynurenins (kynurenin and 3-hydroxikynurenin) accelerate, in conditions of immobilization, the formation of conditioned reflexes and delay the process of their transformation, and also contribute to maintainance of a higher (in comparison with the norm) level of the conditioned activity under monotonous presentation of the signal. The same action is produced by the injection of 1 mcg kynurenin.

Animals↗
PubMed1978

Induction of mutations by photodynamic action of thiopyronine in Saccharomyces cerevisiae.

The induction of cytoplasmic and nuclear mutations by the photodynamic action of thiopyronine is demonstrated in a haploid strain of Saccharomyces cerevisiae that has been isolated as a photodynamic sensitive mutant. No significant increase in corresponding mutation frequencies could be observed in a strain resistant to photodynamic inactivation by thiopyronine.

Cell Nucleus↗
PubMedDate not supplied

Clinical implications of genetic defects in G proteins: oncogenic mutations in G alpha s as the molecular basis for the McCune-Albright syndrome.

Signal-transducing guanine nucleotide-binding proteins (G proteins) couple extracellular receptor proteins to intracellular effector enzymes and ion channels, and therefore are critical mediators of cellular responses to external stimuli. G proteins are comprised of three subunits (alpha, beta, gamma), each encoded by many different genes. The multiplicity of G protein subunits facilitates great combinatorial variability, which, in part, accounts for the ability of G proteins to interact with many different receptor and effector proteins. Hundreds of G protein-coupled receptors have been identified, and their unique patterns of expression among a restricted number of cell types contributes greatly to the apparent specificity of hormone action. Mutations that either activate or inactivate some of these receptors account for a number of highly specific syndromes, which affect a limited number of target tissues. By contrast, most G proteins are widely expressed in many tissues. Accordingly, mutations in these signaling molecules would be expected to produce a more generalized pattern of hormone dysfunction. Activating mutations in the gene (GNAS1) that encode the alpha subunit of the G protein that stimulates adenylyl cyclase (AC) have been identified in many endocrine neoplasms and diverse tissues of patients with McCune-Albright syndrome. The McCune-Albright syndrome is characterized by autonomous endocrine function, hyperpigmented skin lesions, and fibrous dysplasia of bone--effects which reflect the ability of CAMP to stimulate cell function and proliferation in a wide variety of tissues. The unusual features of the McCune-Albright syndrome are explained by the mosaic distribution of cells bearing the mutant allele, an observation that is most consistent with postzygotic mutation of GNAS1. Experimental analysis of this syndrome has extended our understanding of the clinical and biochemical consequences of dysfunctional G protein action and has provided a bench-to-bedside demonstration of the critical role that G proteins play in transmembrane signal transduction in humans.

Animals↗
PubMed2006

Mentalization, insightfulness, and therapeutic action. The importance of mental organization.

Continuing debates over the relative importance of the role of interpretation leading to insight versus the relationship with the analyst as contributing to structural change are based on traditional definitions of insight as gaining knowledge of unconscious content. This definition inevitably privileges verbal interpretation as self-knowledge becomes equated with understanding the contents of the mind. It is suggested that a way out of this debate is to redefine insight as a process, one that is called insightfulness. This term builds on concepts such as mentalization, or theory of mind, and suggests that patients present with difficulties being able to fully mentalize. Awareness of repudiated content will usually accompany the attainment of insightfulness. But the point of insightfulness is to regain access to inhibited or repudiated mentalization, not to specific content, per se. Emphasizing the process of insightfulness integrates the importance of the relationship with the analyst with the facilitation of insightfulness. A variety of interventions help patients gain the capacity to reflect upon and become aware of the intricate workings of their minds, of which verbal interpretation is only one. For example, often it seems less important to focus on a particular conflict than to show interest in our patients' minds. Furthermore, analysands develop insightfulness by becoming interested in and observing our minds in action. Because the mind originates in bodily experience, mental functioning will always fluctuate between action modes of experiencing and expressing and verbal, symbolic modes. The analyst's role becomes making the patient aware of regressions to action modes, understanding the reasons for doing so, and subordinating this tendency to the verbal, symbolic mode. All mental functions work better and facilitate greater self-regulation when they work in abstract, symbolic ways. Psychopathology can be understood as failing to develop or losing the symbolic level of organization, either in circumscribed areas or more ubiquitously. And mutative action occurs through helping our patients attain or regain the symbolic level in regard to all mental functions. Such work is best accomplished in the transference. The concept of transference of defense is expanded to all mental structure, so that transference is seen as the interpersonalization of mental structure. That is, patients transfer their mental structure, including their various levels of mentalizing, into the analytic interaction. The analyst observes all levels of the patient's mental functioning and intervenes to raise them to a symbolic one. At times, this will require action interpretations, allowing oneself to be pulled into an enactment with the patient that is then reprocessed at a verbal, symbolic level. Such actions are not corrective emotional experiences but are interpretations and confrontations of the patient's transferred mental organization at a level affectively and cognitively consistent with the level of communication. Nonetheless, the goal becomes raising the communication to a symbolic level as being able to reflect symbolically on all aspects of one's mind with a minimum of restriction is the greatest guarantee of mental health.

Awareness↗
PubMed1986

[Genetic analysis of Escherichia coli min81 mutation blocking the development of bacteriophage Mu].

Data characterizing mim81 mutation obtained by the method for direct selection of transposition mutations are presented. The development of Mu is shown to be dramatically suppressed in the mutant strain both upon infection and after induction from the lysogenic state. Frequencies of lysogenization and mini-Mu-dependent formation of cointegrates in the mutant strain are comparable with those in the wild-type strain. Mu development prohibition is removed if expression of early Mu gene is provided from the modified Pe promoter. The results obtained make us believe that the mechanism of mim81 mutation action involves reduction of early gene expression to the level that is sufficient for Mu DNA integration into the chromosome during infection and for single replicative events, but insufficient for vegetative development of bacteriophage Mu.

Bacteriophage mu↗
PubMed1995

The transcription factor E2F-1 is a downstream target of RB action.

Reintroduction of RB into SAOS2 (RB-/-) cells causes a G1 arrest and characteristic cellular swelling. Coexpression of the cellular transcription factor E2F-1 could overcome these effects. The ability of E2F-1 to bind to RB was neither necessary nor sufficient for this effect, and S-phase entry was not accompanied by RB hyperphosphorylation under these conditions. Furthermore, E2F-1 could overcome the actions of a nonphosphorylatable but otherwise intact RB mutant. These data, together with the fact that RB binds to E2F-1 in vivo, suggest that E2F-1 is a downstream target of RB action. Mutational analysis showed that the ability of E2F-1 to bind to DNA was necessary and sufficient to block the formation of large cells by RB, whereas the ability to induce S-phase entry required a functional transactivation domain as well. Thus, the induction of a G1 arrest and the formation of large cells by RB in these cells can be genetically dissociated. Furthermore, the ability of the E2F-1 DNA-binding domain alone to block one manifestation of RB action is consistent with the notion that RB-E2F complexes actively repress transcription upon binding to certain E2F-responsive promoters. In keeping with this view, we show here that coproduction of an E2F1 mutant capable of binding to DNA, yet unable to transactivate, is sufficient to block RB-mediated transcriptional repression.

Base Sequence↗
PubMed2026

Integrating germline and tumor sequencing to improve hereditary cancer diagnosis and care.

A subset of cancers arises due to inherited germline pathogenic variants in specific genes, known as hereditary cancers. These genes typically include tumor suppressors, DNA repair and replication fidelity genes, and occasionally oncogenes. In most hereditary cancer syndromes, Knudson's two-hit hypothesis applies, where a second somatic event inactivates the remaining allele of a tumor suppressor or DNA repair gene, leading to tumorigenesis. Advancements in genome-wide sequencing have significantly enhanced our understanding of the mutational processes involved in hereditary cancers. In particular, the assessment of microsatellite instability (MSI), tumor mutational burden (TMB), and mutational signatures has emerged as a powerful tool for the identification of hereditary tumors. Tumors with high or ultra-high TMB often reflect underlying DNA repair deficiencies, while specific mutational signatures can pinpoint the defective pathway. These tumor mutational features are especially informative in syndromes involving mismatch repair (MMR), homologous recombination (HR), base excision repair (BER), nucleotide excision repair (NER), and polymerase proofreading. Moreover, tumor sequencing aids in the interpretation of germline variants, identifies somatic mosaicism, and helps differentiate hereditary from sporadic cancers. Additionally, tumor molecular features associated with DNA repair deficiencies offer insights into personalized therapies, such as the use of PARP inhibitors for BRCA1/2-deficient tumors and immune checkpoint inhibitors for MMR- and polymerase proofreading-deficient cancers. Tumor profiling also uncovers actionable mutations in oncogenes like RET and VHL, which can be targeted with specific therapies. This review explores the integration of tumor molecular features with germline genetic data to refine diagnosis, risk assessment, and therapeutic strategies in hereditary cancer.

Humans↗
PubMed1991

Mutational analysis of the equine infectious anemia virus Tat-responsive element.

A hairpinlike structure is predicted to exist at the 5' end of equine infectious anemia virus (EIAV) RNA which is similar in many ways to the human immunodeficiency type 1 (HIV-1) Tat-responsive element (TAR). In EIAV, this structure has a shorter stem than in HIV-1 and lacks the uridine bulge. Primer extension analysis of EIAV RNA was used to identify the transcriptional start site in the viral long terminal repeat. Premature termination of primer elongation at the predicted double-stranded RNA region was frequently observed and suggests that the inferred hairpin structure exists under these conditions. We have functionally characterized EIAV TAR by site-directed mutagenesis and transient gene expression analysis. It is demonstrated here that the secondary structure of this element is essential for Tat action. Mutations that disrupted base pairing abolished TAR function, and compensatory mutations that restored the stem structure resulted in Tat activation. The TAR loop appears to be closed by two U.G base pairs that are likely to provide a unique structural motif recognized by the Tat protein. With one exception, substitutions of nucleotides within the EIAV loop sequence decreased TAR function. All nucleotide substitutions of the cytidine at position +14 increased EIAV Tat responsiveness; however, its deletion abolished trans activation. Our results lead us to propose that the EIAV and HIV-1 Tat systems employ closely related cis- and trans-acting components that probably act by the same mechanism.

Base Sequence↗
PubMed2026

A Novel BRCA1 Pathogenic Variant in Tunisian Patient With High Grade Ovarian Cancer: Favorable Therapeutic Response to Olaparib.

BACKGROUND: Ovarian cancer is one of the leading causes of death from gynecological cancer worldwide. Genetic mutations in genes involved in key cellular functions such as BRCA1/2 play a central role in tumorigenesis and have major implications for targeted therapeutic strategies, especially the use of poly (ADP-ribose) polymerase (PARP) inhibitors. CASE: Herein, we described a case of a 50-year-old woman diagnosed with severe anemia secondary to heavy menometrorrhagia. Initial gynecological evaluation, including transvaginal ultrasound, was unremarkable, and endometrial biopsy was not indicated. Imaging revealed no ovarian abnormalities; however, exploratory laparotomy identified a peritoneal nodule, leading to further investigation. Targeted NGS was performed on somatic and germline DNA samples and showed a frame shift deletion of 10 bp (c.1256_1265del: p.R419Ter) in the BRCA1 gene. This variant, identified only in tumor tissues, is novel and classified as pathogenic in ClinVar and ACMG databases. Additional somatic alterations were detected in TP53 and MSH6, while germline testing revealed only a variant of uncertain significance in BARD1. After first-line chemotherapy, the patient benefited from olaparib and achieved a progression-free survival of 23 months with good tolerance and no evidence of disease recurrence. CONCLUSION: This finding highlights the importance of integrating tumor-based genomic profiling with germline testing to identify actionable mutations and guide precision oncology. The identification of a novel somatic BRCA1 mutation expands the mutational spectrum of HGSOC and underscores the need to include underrepresented populations, such as those from North Africa, in genomic studies.

Humans↗
PubMed1976

Mutation of Haemophilus influenzae transforming DNA in vitro with near-ultraviolet radiation: action spectrum.

Mutations were produced in purified transforming DNA from Haemophilus influenzae by near-UV radiation and were assayed as mutants among cells transformed with irradiated DNA. The maximum efficiency of mutation induction was at around 334 nm, and the efficiency dropped off steeply at lower and higher wavelengths. The difference between the action spectrum for mutation and that for the oxygen-independent inactivation of transforming DNA, which had a shoulder at 365 nm, indicates that there are different lesions involved in the inactivating and mutagenic effects of near-UV. The presence of histidine during irradiation enhanced the mutagenic effect at 334 and 365 nm, although it protected against inactivation at 365 nm. The effective near-UV wavelengths for in vitro mutation are to some extent the same as the effective wavelengths for mutation in vivo reported previously. These findings indicate that mutations are produced in vivo by near-UV with DNA as the primary target molecule rather than by a secondary non-photochemical reaction between DNA and some other cell component.

DNA, Bacterial↗
PubMed2025

Clinical utility of comprehensive genomic profiling test for colorectal cancer: a single institution prospective observational study.

PURPOSE: Next-generation sequencing (NGS) has revolutionized cancer treatment by enabling comprehensive cancer genomic profiling (CGP) to guide genotype-directed therapies. While several prospective trials have demonstrated varying outcomes with CGP in patients with advanced solid tumors, its clinical utility in colorectal cancer (CRC) remains to be evaluated. METHODS: We conducted a prospective observational study of CGP in our hospital between September 2019 and March 2024. Overall survival (OS) of the patients who received CGP-based therapy and those did not was compared, and genomic variables associated with OS were evaluated. RESULTS: A total of 100 patients with CRC underwent CGP using four platforms. The median patient age was 67 years, and most had a good performance status. The most frequent genomic alterations were TP53 (82%), APC (82%), and KRAS (55%). Actionable mutations such as ERBB2 amplification and BRAF V600E were identified in some patients, and 9% received CGP-based therapy, including immune checkpoint inhibitors for tumor mutational burden-high or microsatellite instability-high tumors. Patients receiving CGP-based therapy had longer OS from expert panel discussion (16.0 vs. 10.8 months) compared to those who did not. Alterations in TP53, SMAD4, and NF1 were associated with worse OS. Interestingly, PTEN mutations were linked to improved survival. TP53 alterations were more common in left-sided CRC. CONCLUSION: Although some patients with CRC received CGP-guided therapy, a statistically significant survival benefit was not observed. However, TP53 and SMAD4 mutations were identified as negative prognostic markers, indicating their potential as targets for future drug development.

Humans↗
PubMed2004

Arabidopsis EIN3-binding F-box 1 and 2 form ubiquitin-protein ligases that repress ethylene action and promote growth by directing EIN3 degradation.

Ubiquitination of various intracellular proteins by ubiquitin-protein ligases (or E3s) plays an essential role in eukaryotic cell regulation primarily through its ability to selectively target proteins for degradation by the 26S proteasome. Skp1, Cullin, F-box (SCF) complexes are one influential E3 class that use F-box proteins to deliver targets to a core ligase activity provided by the Skp1, Cullin, and Rbx1 subunits. Almost 700 F-box proteins can be found in Arabidopsis, indicating that SCF E3s likely play a pervasive role in plant physiology and development. Here, we describe the reverse genetic analysis of two F-box proteins, EBF1 and -2, that work coordinately in SCF complexes to repress ethylene action. Mutations in either gene cause hypersensitivity to exogenous ethylene and its precursor 1-aminocyclopropane-1-carboxylic acid. EBF1 and -2 interact directly with ethylene insensitive 3 (EIN3), a transcriptional regulator important for ethylene signaling. Levels of EIN3 are increased in mutants affecting either EBF1 or -2, suggesting that the corresponding SCF complexes work together in EIN3 breakdown. Surprisingly, double ebf1 ebf2 mutants display a substantial arrest of seedling growth and have elevated EIN3 levels, even in the absence of exogenous ethylene. Collectively, our results show that the SCF(EBF1/EBF2)-dependent ubiquitination and subsequent removal of EIN3 is critical not only for proper ethylene signaling but also for growth in plants.

Amino Acid Sequence↗
PubMed1989

Pathways of human cell post-replication repair.

Mutagenesis, clastogenesis, and carcinogenesis, may all be S-phase dependent processes within carcinogen-damaged human cells. Carcinogens have been shown to inhibit replicative DNA synthesis in S phase cells and the mechanisms of inhibition have been identified. It is proposed that the sequelae of carcinogen action (mutations, sister-chromatid exchanges, chromosome aberrations) are the consequence of the production of lesions in the DNA template which interfere with the ability of DNA polymerase to synthesize a complementary strand without error. Mis-instructive lesions in the template give rise to base-substitution mutations in nascent strands as DNA polymerase inserts an incorrect but complementary base. Non-instructive base lesions and sterically interfering bulky adducts in the template inhibit DNA polymerase and cause the growing points of nascent DNA strands to be blocked. This blockage perpetuates discontinuities in daughter strands. These discontinuities are eliminated by a process known as post-replication repair. Blocked growing points may be relieved by un-directed insertion of DNA precursors to span the non-instructive lesions. Transient dislocation of the primer terminus from the damaged template may occur at palindromic or repetitive sequences. Reannealing of the primer terminus beyond the site of damage may allow bypass of blocking lesions with a consequence of deletion or insertion of genetic information. DNA at the site of blocked growing points may be a substrate for other enzymes involved in DNA metabolism. Single-strand gaps in daughter strands may be recognized by Rec A-like proteins which catalyze paranemic invasion of sister duplex strands. Recombination intermediates generated at sites of blocked growing points may be resolved by a pathway that produces either sister-chromatid exchanges or the insertion of a patch of parental template DNA within the daughter strand. Single-strand-specific endonuclease may attack regions of denatured DNA at blocked growing points producing double-strand breaks which appear to be intermediates in the formation of chromatid aberrations. The utilization of each of these pathways of post-replication repair will depend upon the precise structure of the template lesion, the sequence context in which the lesion is embedded in the template strand, and stochastic processes.

Cell Cycle↗
PubMed1999

AUX1 regulates root gravitropism in Arabidopsis by facilitating auxin uptake within root apical tissues.

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.

Arabidopsis↗