Transcription System Research Articles

Analyzing lower half facial gestures for lip reading applications: Survey on vision techniques

Lip reading has gained popularity due to the proliferation of emerging real-world applications. This article provides a comprehensive review of benchmark datasets available for lip-reading applications and pioneering works that analyze lower facial cues for lip-reading applications. A comprehensive review of lip reading applications is broadly classified into five distinct applications: Lip Reading Biometrics (LRB), Audio Visual Speech Recognition (AVSR), Silent Speech Recognition (SSR), Voice from Lips, and Lip HCI (Human–computer interaction). LRB entails extensive research in the fields of authentication and liveness detection. AVSR covers key findings that have contributed significantly to applications such as voice assistants, video-to-text transcription, hearing aids, and pronunciation-correcting systems. SSR analyzes the efforts made for silent-video-to-text transcription and surveillance camera applications. The voice from lips section discusses applications such as voice for the voiceless and vision-infused speech inpainting. In lip HCI, LR-HCI for smartphones, smart TVs, computers, robots, and musical instruments is reviewed in detail. Comprehensive coverage is given to cutting-edge techniques in computer vision, signal processing, machine learning, and deep learning. The advancements that aid the system in learning to lip-read and authenticate lip gestures, generate text transcription, synthesize voice based on lip movements, and control systems via lip movements (lip HCI) are covered. The work concludes by highlighting the limitations of existing frameworks, the road maps of each application illustrating the evolution of techniques employed over time, and future research avenues in lip-reading applications.

Investigating The Hausa Students' Familiarity And Satisfaction With The Applicability And Efficiency Of X-SAMPA For Transcribing African Languages

This article investigates the applicability and efficiency of the X-SAMPA phonetic transcription system for African languages, with a particular focus on the Hausa language. The study aims to assess the familiarity and proficiency of final-year Hausa language students in using X-SAMPA to transcribe Hausa speech sounds accurately. Data for the study was collected through electronic questionnaires distributed to final-year Hausa language students at different universities in Nigeria. The study findings indicate that X-SAMPA is a valuable tool for transcribing the Hausa language, as it provides a standardized and simplified transcription system that can be used across different research works. However, many Hausa language students were unfamiliar with X-SAMPA and required more training to become proficient in its use. Lack of time and practice opportunities were identified as the primary barriers to learning X-SAMPA. The study concludes that X-SAMPA has the potential for wider usage in phonetic transcription of African languages, but more resources such as written or video tutorials and practice exercises are needed to help learners become proficient in its use. Based on the research findings, the article recommends organizing training workshops or courses to enhance the knowledge of Hausa language students interested in learning X-SAMPA.

Histoire de la description de la parole: de l'introspection à l'instrumentation éd. par Christelle Dodane, et Claudia Schweitzer

Reviewed by: Histoire de la description de la parole: de l'introspection à l'instrumentation éd. par Christelle Dodane, et Claudia Schweitzer Wladyslaw Cichocki Dodane, Christelle, et Claudia Schweitzer, éd. Histoire de la description de la parole: de l'introspection à l'instrumentation. Champion, 2021. ISBN 978-2-7453-5595-9. Pp. 404. This collection of eleven papers (plus a preface and an afterword) deals with aspects of the historical development—from the sixteenth to the early twentieth centuries—of the description of speech as found in research on French. The main theme is that the notations and analytical techniques currently used in phonetic research were developed over a long period of time. Before the nineteenth century, knowledge about speech was limited to what could be perceived by auditory perception, physical observation, or intuition. However, major developments in speech research were to take place in the late nineteenth century with the invention of analytical instruments such as the kymograph, palatographic mirrors, and magnetic recordings. This theme is developed in each of the three sections of the book. The first section discusses the description of prosody. While sixteenth-century grammarians considered prosody to be an important part of rhetorical art, they tended to avoid it in their research because they had difficulty describing it. The discovery of instruments that brought into focus the acoustic features of fundamental frequency, intensity, and duration helped in the creation of notational systems that were sensitive to the organization of rhythm and intonation. The second section of the book presents the development of transcription systems for segmental sounds. Research began with two types of systems, "organic" notations based on physiological articulation and writing systems that were close to the Latin alphabet; these would eventually lead to the invention of the International Phonetic Alphabet. The third section of papers outlines the growth of experimental phonetics laboratories in Paris, Grenoble, Montpellier, and Strasbourg. It establishes connections between this development and research on déclamation, gesture, and singing. Among the topics covered are the legacies of Abbé Jean-Pierre Rousselot, the phonetician and dialectologist who was the founder of experimental phonetics, and Maurice Grammont, whose research on phonetic variation was a precursor to the field of sociophonetics. Many of the nineteen specialists who contributed papers to this volume are associated with the Praxiling Laboratoire de linguistique at Université Paul-Valéry Montpellier 3, and they represent different fields: phonetics, phonology, speech pathology, musicology, history of linguistics, and traditional grammar. This diversity may account for some of the differences in writing style and for the loose cohesion between chapters. A noticeable shortcoming is the small number of illustrations in the chapters that discuss the development of transcription systems. It is noteworthy that the volume is accompanied by an online booklet that provides links to videos and excerpts from rare manuscripts (including portraits, descriptive texts, and demonstrations of instruments like the kymograph). This book will be of particular [End Page 171] interest to phoneticians and advanced students of phonetics as well as to those who study the history of linguistics. More generally, anyone who carries out computer-based analysis of speech—using software such as Praat, for example—will find useful historical nuggets that inspire an appreciation of and reflection on the origins of current notational and instrumental practices. [End Page 172] Wladyslaw Cichocki University of New Brunswick (Canada) Copyright © 2023 American Association of Teachers of French

Regulatory Role of Anti-Sigma Factor RsbW in Clostridioides difficile Stress Response, Persistence, and Infection.

The anaerobic pathogen Clostridioides difficile, which is a primary cause of antibiotic-associated diarrhea, faces a variety of stresses in the environment and in the mammalian gut. To cope with these stresses, alternative sigma factor B (σB) is employed to modulate gene transcription, and σB is regulated by an anti-sigma factor, RsbW. To understand the role of RsbW in C. difficile physiology, a rsbW mutant (ΔrsbW), in which σB is assumed to be "always on," was generated. ΔrsbW did not show fitness defects in the absence of stress but tolerated acidic environments and detoxified reactive oxygen and nitrogen species better compared to the parental strain. ΔrsbW was defective in spore and biofilm formation, but it displayed increased adhesion to human gut epithelia and was less virulent in a Galleria mellonella infection model. A transcriptomic analysis to understand the unique phenotype of ΔrsbW showed changes in expression of genes associated with stress responses, virulence, sporulation, phage, and several σB-controlled regulators, including the pleiotropic regulator sinRR'. While these profiles were distinct to ΔrsbW, changes in some σB-controlled stress-associated genes were similar to those reported in the absence of σB. Further analysis of ΔrsbW showed unexpected lower intracellular levels of σB, suggesting an additional post-translational control mechanism for σB in the absence of stress. Our study provides insight into the regulatory role of RsbW and the complexity of regulatory networks mediating stress responses in C. difficile. IMPORTANCE Pathogens like Clostridioides difficile face a range of stresses in the environment and within the host. Alternative transcriptional factors like sigma factor B (σB) enable the bacterium to respond quickly to different stresses. Anti-sigma factors like RsbW control sigma factors and therefore the activation of genes via these pathways. Some of these transcriptional control systems provide C. difficile with the ability to tolerate and detoxify harmful compounds. Here, we investigate the role of RsbW in C. difficile physiology. We demonstrate distinctive phenotypes for a rsbW mutant in growth, persistence, and virulence and suggest alternate σB control mechanisms in C. difficile. Understanding C. difficile responses to external stress is key to designing better strategies to combat this highly resilient bacterial pathogen.

A Suite of Constitutive Promoters for Tuning Gene Expression in Plants.

The need for convenient tools to express transgenes over a large dynamic range is pervasive throughout plant synthetic biology; however, current efforts are largely limited by the heavy reliance on a small set of strong promoters, precluding more nuanced and refined engineering endeavors in planta. To address this technical gap, we characterize a suite of constitutive promoters that span a wide range of transcriptional levels and develop a GoldenGate-based plasmid toolkit named PCONS, optimized for versatile cloning and rapid testing of transgene expression at varying strengths. We demonstrate how easy access to a stepwise gradient of expression levels can be used for optimizing synthetic transcriptional systems and the production of small molecules in planta. We also systematically investigate the potential of using PCONS as an internal standard in plant biology experimental design, establishing the best practices for signal normalization in experiments. Although our library has primarily been developed for optimizing expression in N. benthamiana, we demonstrate the translatability of our promoters across distantly related species using a multiplexed reporter assay with barcoded transcripts. Our findings showcase the advantages of the PCONS library as an invaluable toolkit for plant synthetic biology.

The role of replication-induced chromosomal copy numbers in spatio-temporal gene regulation and evolutionary chromosome plasticity.

For a coherent response to environmental changes, bacterial evolution has formed a complex transcriptional regulatory system comprising classical DNA binding proteins sigma factors and modulation of DNA topology. In this study, we investigate replication-induced gene copy numbers - a regulatory concept that is unlike the others not based on modulation of promoter activity but on replication dynamics. We show that a large fraction of genes are predominantly affected by transient copy numbers and identify cellular functions and central pathways governed by this mechanism in Escherichia coli. Furthermore, we show quantitatively that the previously observed spatio-temporal expression pattern between different growth phases mainly emerges from transient chromosomal copy numbers. We extend the analysis to the plant pathogen Dickeya dadantii and the biotechnologically relevant organism Vibrio natriegens. The analysis reveals a connection between growth phase dependent gene expression and evolutionary gene migration in these species. A further extension to the bacterial kingdom indicates that chromosome evolution is governed by growth rate related transient copy numbers.

ReViTA: A novel in vitro transcription system to study gene regulation

ReViTA (Reverse in VitroTranscription Assay) is a novel in vitro transcription-based method to study gene expression under the regulation of specific transcription factors. The ReViTA system uses a plasmid with a control sequence, the promoter region of the studied gene, the transcription factor of interest, and an RNA polymerase saturated with σ70. The main objective of this study was to evaluate the method; thus, as a proof of concept, two different transcription factors were used, a transcriptional inducer, AlgR, and a repressor, LexA, from Pseudomonas aeruginosa. After the promoters were incubated with the transcription factors, the plasmid was transcribed into RNA and reverse transcribed to cDNA. Gene expression was measured using qRTPCR. Using the ReViTA plasmid, transcription induction of 55% was observed when AlgR protein was added and a 27% transcription reduction with the repressor LexA, compared with the samples without transcription factors. The results demonstrated the correct functioning of ReViTA as a novel method to study transcription factors and gene expression. Thus, ReViTA could be a rapid and accessible in vitro method to evaluate genes and regulators of various species.

Developing an efficient CRISPR–dCas9–TV-derived transcriptional activation system to create three novel cotton germplasm materials

Developing an efficient CRISPR–dCas9–TV-derived transcriptional activation system to create three novel cotton germplasm materials

Research on Robust Audio-Visual Speech Recognition Algorithms

Automatic speech recognition (ASR) that relies on audio input suffers from significant degradation in noisy conditions and is particularly vulnerable to speech interference. However, video recordings of speech capture both visual and audio signals, providing a potent source of information for training speech models. Audiovisual speech recognition (AVSR) systems enhance the robustness of ASR by incorporating visual information from lip movements and associated sound production in addition to the auditory input. There are many audiovisual speech recognition models and systems for speech transcription, but most of them have been tested based in a single experimental setting and with a limited dataset. However, a good model should be applicable to any scenario. Our main contributions are: (i) Reproducing the three best-performing audiovisual speech recognition models in the current AVSR research area using the most famous audiovisual databases, LSR2 (Lip Reading Sentences 2) LSR3 (Lip Reading Sentences 3), and comparing and analyzing their performances under various noise conditions. (ii) Based on our experimental and research experiences, we analyzed the problems currently encountered in the AVSR domain, which are summarized as the feature-extraction problem and the domain-generalization problem. (iii) According to the experimental results, the Moco (momentum contrast) + word2vec (word to vector) model has the best AVSR effect on the LRS datasets regardless of whether there is noise or not. Additionally, the model also produced the best experimental results in the experiments of audio recognition and video recognition. Our research lays the foundation for further improving the performance of AVSR models.

Label-Free Detection of T4 Polynucleotide Kinase Activity and Inhibition via Malachite Green Aptamer Generated from Ligation-Triggered Transcription.

Polynucleotide kinase (PNK) is a key enzyme that is necessary for ligation-based DNA repair. The activity assay and inhibitor screening for PNK may contribute to the prediction and improvement of tumor treatment sensitivity, respectively. Herein, we developed a simple, low-background, and label-free method for both T4 PNK activity detection and inhibitor screening by combining a designed ligation-triggered T7 transcriptional amplification system and a crafty light-up malachite green aptamer. Moreover, this method successfully detected PNK activity in the complex biological matrix with satisfactory outcomes, indicating its great potential in clinical practice.

Characterization of radiation-resistance mechanism in Spirosoma montaniterrae DY10T in terms of transcriptional regulatory system

To respond to the external environmental changes for survival, bacteria regulates expression of a number of genes including transcription factors (TFs). To characterize complex biological phenomena, a biological system-level approach is necessary. Here we utilized six computational biology methods to infer regulatory network and to characterize underlying biologically mechanisms relevant to radiation-resistance. In particular, we inferred gene regulatory network (GRN) and operons of radiation-resistance bacterium Spirosoma montaniterrae DY10^T and identified the major regulators for radiation-resistance. Our results showed that DNA repair and reactive oxygen species (ROS) scavenging mechanisms are key processes and Crp/Fnr family transcriptional regulator works as a master regulatory TF in early response to radiation.

What’s in the r? A review of the usage of the r symbol in the Illustrations of the IPA

What does the symbol r mean when it is used in a transcription? Here we analyze the use of the symbols for the alveolar trills (r) and taps () among the Illustrations of the IPA since 1971. We begin by sketching the history of the various symbols and conventions used to represent the trill and the tap in two transcription traditions: the Americanist Transcription System and the International Phonetic Alphabet. From the 213 languages covered until 2021, we carefully analyze the 162 that have trills and/or taps, using the information provided in Illustrations. Our results show that r tends to be used to represent a generic ‘r-like’ sound in both transcription traditions. More precisely, by comparing the use of r in the consonant tables and in the transcriptions of their accompanying narrative texts, we show that r is not systematically associated with an alveolar trill. Furthermore, we show that phonetic trills are less frequent than phonetic taps, while phonemic trills are more frequent than phonemic taps. As a consequence, inferring the presence of trilling in a sound system from the presence of r in its transcription is not as straightforward as one might expect. These findings highlight the critical importance of being absolutely explicit about the meaning of the various symbols found in grammars and secondary databases, and of r in particular, as a preliminary step in a broad range of studies, including cross-linguistic comparisons, inferences about the past or generalizations about language acquisition and articulatory effort.

TURN-TAKING FEATURES IN TONI TALKS: A CONVERSATION ANALYSIS

This study is developed in order to determine the turn taking features in Toni talks to the use of conversation analysis. This study sought to answer two main questions: (1) What are the turn taking features that are observed in Toni talks under the life story and political theme category, (2) What are the similarities and differences of the turn taking features in the selected Toni talk’s episodes? To answer the research questions, the researchers used qualitative research design and in order for the data to be transcribed, the researchers utilized the Jefferson transcription system or the Jeffersonian transcription (2004) to yield the result of analysis. In conclusion, turn taking features such as mention, overlap, interruption, back channel, taking the floor/starting up, yielding the floor, and holding the floor was observed in this study as well as the features that was mostly utilized among the seven (7) turn taking features and how this substantiate the following Toni talks interviews. Results also explicated several key factors that motivate the utilization of the features, the similarities and differences of the chosen interviews, and the specific implications of the features in the course of the interviews.

Precise programming of multigene expression stoichiometry in mammalian cells by a modular and programmable transcriptional system

Context-dependency of mammalian transcriptional elements has hindered the quantitative investigation of multigene expression stoichiometry and its biological functions. Here, we describe a host- and local DNA context-independent transcription system to gradually fine-tune single and multiple gene expression with predictable stoichiometries. The mammalian transcription system is composed of a library of modular and programmable promoters from bacteriophage and its cognate RNA polymerase (RNAP) fused to a capping enzyme. The relative expression of single genes is quantitatively determined by the relative binding affinity of the RNAP to the promoters, while multigene expression stoichiometry is predicted by a simple biochemical model with resource competition. We use these programmable and modular promoters to predictably tune the expression of three components of an influenza A virus-like particle (VLP). Optimized stoichiometry leads to a 2-fold yield of intact VLP complexes. The host-independent orthogonal transcription system provides a platform for dose-dependent control of multiple protein expression which may be applied for advanced vaccine engineering, cell-fate programming and other therapeutic applications.

Combinatorial protein dimerization enables precise multi-input synthetic computations

Bacterial transcription factors (TFs) with helix-turn-helix (HTH) DNA-binding domains have been widely explored to build orthogonal transcriptional regulation systems in mammalian cells. Here we capitalize on the modular structure of these proteins to build a framework for multi-input logic gates relying on serial combinations of inducible protein–protein interactions. We found that for some TFs, their HTH domain alone is sufficient for DNA binding. By fusing the HTH domain to TFs, we established dimerization dependent rather than DNA-binding-dependent activation. This enabled us to convert gene switches from OFF-type into more widely applicable ON-type systems and to create mammalian gene switches responsive to new inducers. By combining both OFF and ON modes of action, we built a compact, high-performance bandpass filter. Furthermore, we were able to show cytosolic and extracellular dimerization. Cascading up to five pairwise fusion proteins yielded robust multi-input AND logic gates. Combinations of different pairwise fusion proteins afforded a variety of 4-input 1-output AND and OR logic gate configurations.

Hepatic genomic assessment of dietary ingestion of 2-aminoanthracene in Sprague Dawley rats

This research aims to investigate the effects of 2-aminoanthracene (2-AA), a polycyclic aromatic hydrocarbon (PAH), on the liver. PAH is a by-product of the incomplete combustion of fossil fuels. Specifically, the impact of 2-AA on different body tissues in animals has been reported. The liver is an organ central to the metabolism of PAHs, including 2-AA. Sprague Dawley rats ingested a well-defined dose of 2-AA in their diet (0, 50, and 100 mg/kg 2-AA) for 12 weeks. Hepatic global gene expression using Affymetrix Rat Genome 230 2.0 microarray was performed. Overall, more than 17,000 genes were expressed. Approximately 70 genes were upregulated, while 65 were downregulated when control rats were compared with low-dose animals. Similarly, 103 genes were upregulated and 49 downregulated when the high-concentration 2-AA group was compared with the control group rats. This result suggests that the magnitude of gene expression fold change depends on the dose of 2-AA ingested. Several differentially expressed genes are involved in biological processes such as gene transcription, cell cycle, and immune system function, indicating that the ingestion of 2-AA could impact these processes. The over-expression of genes related to liver inflammation, nonalcoholic liver disease, hepatic glucose processing, and PAH metabolism were noted.

Robust protein-based engineering of hepatocyte-like cells from human mesenchymal stem cells.

Cells of interest can be prepared from somatic cells by forced expression of lineage-specific transcription factors, but it is required to establish a vector-free system for their clinical use. Here, we report a protein-based artificial transcription system for engineering hepatocyte-like cells from human umbilical cord-derived mesenchymal stem cells (MSCs). MSCs were treated for 5 days with 4 artificial transcription factors (4F), which targeted hepatocyte nuclear factor (HNF)1α, HNF3γ, HNF4α, and GATA-binding protein 4 (GATA4). Then, engineered MSCs (4F-Heps) were subjected to epigenetic analysis, biochemical analysis and flow cytometry analysis with antibodies to marker proteins of mature hepatocytes and hepatic progenitors such as delta-like homolog 1 (DLK1) and trophoblast cell surface antigen 2 (TROP2). Functional properties of the cells were also examined by injecting them to mice with lethal hepatic failure. Epigenetic analysis revealed that a 5-day treatment of 4F upregulated the expression of genes involved in hepatic differentiation, and repressed genes related to pluripotency of MSCs. Flow cytometry analysis detected that 4F-Heps were composed of small numbers of mature hepatocytes (at most 1%), bile duct cells (~19%) and hepatic progenitors (~50%). Interestingly, ~20% of 4F-Heps were positive for cytochrome P450 3A4, 80% of which were DLK1-positive. Injection of 4F-Heps significantly increased survival of mice with lethal hepatic failure, and transplanted 4F-Heps expanded to more than 50-fold of human albumin-positive cells in the mouse livers, well consistent with the observation that 4F-Heps contained DLK1-positive and/or TROP2-positive cells. Taken together with observations that 4F-Heps were not tumorigenic in immunocompromised mice for at least 2 years, we propose that this artificial transcription system is a versatile tool for cell therapy for hepatic failures.

Design of an artificial transcriptional system for production of high levels of recombinant proteins in tobacco (Nicotiana benthamiana).

Plants have recently received much attention as a means of producing recombinant proteins because they are easy to grow at a low cost and at a large scale. Although many plant protein expression systems have been developed, there remains a need for improved systems that deliver high yields of recombinant proteins. Transcription of the recombinant gene is a key step in increasing the yield of recombinant proteins. However, revealed strong promoters, terminators, and transcription factors that have been identified do not necessarily lead to high level production of recombinant proteins. Thus, in this study, a robust expression system was designed to produce high levels of recombinant protein consisting of a novel hybrid promoter, FM'M-UD, coupled with an artificial terminator, 3PRt. FM'M-UD contained fragments from three viral promoters (the promoters of Mirabilis mosaic caulimovirus (MMV) full-length transcript, the MMV subgenomic transcript, and figwort mosaic virus subgenomic transcript) and two types of cis-acting elements (four GAL4 binding sites and two zinc finger binding sites). The artificial terminator, 3PRt, consisted of the PINII and 35S terminators plus RB7, a matrix attachment region. The FM'M-UD promoter increased protein levels of reporters GFP, RBD : SD1 (part of S protein from SARS-CoV-2), and human interleukin-6 (hIL6) by 4-6-fold, 2-fold, and 6-fold, respectively, relative to those of the same reporters driven by the CaMV 35S promoter. Furthermore, when the FM'M-UD/3PRt expression cassette was expressed together with GAL4/TAC3d2, an artificial transcription factor that bound the GAL4 binding sites in FM'M-UD, levels of hIL6 increased by 10.7-fold, relative to those obtained from the CaMV 35S promoter plus the RD29B terminator. Thus, this novel expression system led to the production of a large amount of recombinant protein in plants.

On the Role of TATA Boxes and TATA-Binding Protein in Arabidopsis thaliana.

For transcription initiation by RNA polymerase II (Pol II), all eukaryotes require assembly of basal transcription machinery on the core promoter, a region located approximately in the locus spanning a transcription start site (-50; +50 bp). Although Pol II is a complex multi-subunit enzyme conserved among all eukaryotes, it cannot initiate transcription without the participation of many other proteins. Transcription initiation on TATA-containing promoters requires the assembly of the preinitiation complex; this process is triggered by an interaction of TATA-binding protein (TBP, a component of the general transcription factor TFIID (transcription factor II D)) with a TATA box. The interaction of TBP with various TATA boxes in plants, in particular Arabidopsis thaliana, has hardly been investigated, except for a few early studies that addressed the role of a TATA box and substitutions in it in plant transcription systems. This is despite the fact that the interaction of TBP with TATA boxes and their variants can be used to regulate transcription. In this review, we examine the roles of some general transcription factors in the assembly of the basal transcription complex, as well as functions of TATA boxes of the model plant A. thaliana. We review examples showing not only the involvement of TATA boxes in the initiation of transcription machinery assembly but also their indirect participation in plant adaptation to environmental conditions in responses to light and other phenomena. Examples of an influence of the expression levels of A. thaliana TBP1 and TBP2 on morphological traits of the plants are also examined. We summarize available functional data on these two early players that trigger the assembly of transcription machinery. This information will deepen the understanding of the mechanisms underlying transcription by Pol II in plants and will help to utilize the functions of the interaction of TBP with TATA boxes in practice.

Live cell single molecule imaging reveals concentration dependent changes to dynamic behavior of nuclear receptors RAR and RXR.

Type 2 Nuclear Receptors (T2NRs) like Retinoic Acid Receptor (RAR) are believed to require heterodimerization with a common factor, the Retinoid X Receptor (RXR), to bind chromatin and regulate its target genes. Here, we deploy stroboscopic photo-activation SPT (spaSPT) to understand the molecular dynamics of the RAR/RXR system and infer different diffusion states acquired by RAR and RXR in the nucleoplasm. These states occupied by RAR and RXR presumably exist in dynamic equilibrium. Next, we ask in a complex heterodimer driven transcriptional regulatory system such as this, how is the dynamic equilibrium shifted when either of the heterodimeric partner is in excess. We find that in live cells, increasing the number of RAR molecules and not RXR molecules leads to altered chromatin binding of RAR. While increasing the number of molecules of RAR and RXR both alter the chromatin binding of RXR. Since pharmacological modulation of the RAR/RXR system is an important avenue for cancer treatments, this study constitutes a step toward understanding how perturbations of this system affect chromatin binding and possibly downstream transcriptional regulatory function.