GRK2 kinases in the primary cilium initiate SMOOTHENED-PKA signaling in the Hedgehog cascade.

During Hedgehog (Hh) signal transduction in development and disease, the atypical G protein-coupled receptor (GPCR) SMOOTHENED (SMO) communicates with GLI transcription factors by binding the protein kinase A catalytic subunit (PKA-C) and physically blocking its enzymatic activity. Here, we show that GPCR kinase 2 (GRK2) orchestrates this process during endogenous mouse and zebrafish Hh pathway activation in the primary cilium. Upon SMO activation, GRK2 rapidly relocalizes from the ciliary base to the shaft, triggering SMO phosphorylation and PKA-C interaction. Reconstitution studies reveal that GRK2 phosphorylation enables active SMO to bind PKA-C directly. Lastly, the SMO-GRK2-PKA pathway underlies Hh signal transduction in a range of cellular and in vivo models. Thus, GRK2 phosphorylation of ciliary SMO and the ensuing PKA-C binding and inactivation are critical initiating events for the intracellular steps in Hh signaling. More broadly, our study suggests an expanded role for GRKs in enabling direct GPCR interactions with diverse intracellular effectors.

Effects of wind-driven current and thermal dynamics in a temperate monomictic reservoir: Implications for manganese transport and treatment in water supply systems.

Increasing manganese (Mn) concentrations in source water contribute to aesthetic and health-related concerns in drinking water. The challenges with Mn in drinking water primarily arise from elevated Mn concentrations in the water supply reservoir, with the inefficacy of Mn treatment largely attributed to fluctuating Mn levels in the water source. A three-dimensional Mn cycle model in a temperate monomictic reservoir, Tarago Reservoir, and a decision support system reflecting Mn variations in the local water treatment plant have been established in previous research. This study aimed to examine Mn variations from the reservoir to raw water and treated water under the influence of wind conditions during different stages of thermal structure, and discover valuable recommendations for Mn treatment in the local water supply system. We crafted 12 scenarios to scrutinize the impact of varying intensities of offshore and onshore winds on hydrodynamic processes and Mn transport during strong thermal stratification, weak thermal stratification, and turnover. The scenario analysis revealed that, during the gradual weakening of thermal stratification, offshore wind induced a substantial amount of Mn to the upper layers near the water intake point. Conversely, onshore wind hindered the upward transport of Mn. The simulated Mn in the raw water under the 12 scenarios indicated that the timing of turnover in the Tarago Reservoir is the primary concern for Mn treatment in the water treatment plant. Additionally, close attention should be given to the frequency and intensity of offshore winds during the weakening of thermal stratification.

A novel mathematical template for developing fDOM probe fluorescence signal correction models for freshwaters.

The reliable application of field deployable fluorescent dissolved organic matter (fDOM) probes is hindered by several influencing factors which need to be compensated. This manuscript describes the corrections of temperature, pH, turbidity and inner filter effect on fluorescence signal of a commercial fDOM probe (fDOMs). For this, Australian waters with wide ranging qualities were selected, e.g. dissolved organic carbon (DOC) ranging from ∼1 to ∼30 mg/L, specific UV absorbance at 254 nm from ∼1 to ∼6 L/m/mg and turbidity from ∼1 to ∼ 350 FNU. Laboratory-based model calibration experiments (MCEs) were performed. A model template was developed and used for the development of the correction models. For each factor, data generated through MCEs were used to determine model coefficient (α) values by fitting the generated model to the experimental data. Four discrete factor models were generated by determination of a factor-specific α value. The α values derived for each water of the MCEs subset were consistent for each factor model. This indicated generic nature of the four α values across wide-ranging water qualities. High correlation between fDOMs and DOC were achieved after applying the four-factor compensation models to new data (r, 0.96, p < 0.05). Also, average biases (and %) between DOC predicted through fDOMs and actual DOC were decreased by applying the four-factor compensation model (from 3.54 (60.9%) to 1.28 (16.7%) mg/L DOC). These correction models were incorporated into a Microsoft EXCEL-based software termed EXOf-Correct for ready-to-use applications.

Catching nano: Evaluating the fate and behaviour of nano-TiO2 in swimming pools through dynamic simulation modelling.

Engineered titanium dioxide nanoparticles (nano-TiO2) in consumer products such as sunscreens widely used by swimmers in aquatic settings have raised concerns about their potential adverse impact on ecosystems and human health due to their small size and unique physicochemical properties. Therefore, this research paper aims to investigate the fate and behaviour of nano-TiO2 from sunscreens in swimming pools using System Dynamics Modelling. The study developed a dynamic simulation model that considers various factors, including weather conditions, sunscreen and pool usage behaviour, filtration efficacy, pool maintenance, water chemistry, pool chemicals, and TiO2 concentration levels, which can affect exposure levels for different scenarios. The study considered non-linear interdependent relationships, feedback structures, and temporal changes and dealt with parameter uncertainties through Monte Carlo analyses. The results reveal that the regular use of sunscreen leads to nano-TiO2 concentrations ranging from 0.001 to 0.05 mg/L within a year, reflecting seasonal and pool usage variations. The study also found that changes in the weight percentage of TiO2 in the sunscreen formulation and the filtration duration per day are the most sensitive factors affecting TiO2 concentrations. Scenario analyses exploring different nano-TiO2 removal strategies suggested that one daily turnover is necessary for sufficient removal. Regular manual pool maintenance and monthly use of a pool clarifier are recommended for enhanced and accelerated removal without substantial additional costs. The study is novel in its integrated approach, combining empirical work with dynamic simulations, resulting in a novel approach to model the environmental fate and behaviour of nano-TiO2. The study makes important methodological contributions to the field and has initiated an interdisciplinary collaboration to create more accurate models. This study is of great significance as it presents a pioneering analysis of the impact of sunscreen properties, user behaviour, and environmental stressors on the fate and behaviour of nano-TiO2 in swimming pools.

Application of Eye Tracking Technology in Aviation, Maritime, and Construction Industries: A Systematic Review.

Most accidents in the aviation, maritime, and construction industries are caused by human error, which can be traced back to impaired mental performance and attention failure. In 1596, Du Laurens, a French anatomist and medical scientist, said that the eyes are the windows of the mind. Eye tracking research dates back almost 150 years and it has been widely used in different fields for several purposes. Overall, eye tracking technologies provide the means to capture in real time a variety of eye movements that reflect different human cognitive, emotional, and physiological states, which can be used to gain a wider understanding of the human mind in different scenarios. This systematic literature review explored the different applications of eye tracking research in three high-risk industries, namely aviation, maritime, and construction. The results of this research uncovered the demographic distribution and applications of eye tracking research, as well as the different technologies that have been integrated to study the visual, cognitive, and attentional aspects of human mental performance. Moreover, different research gaps and potential future research directions were highlighted in relation to the usage of additional technologies to support, validate, and enhance eye tracking research to better understand human mental performance.

Taxonomy and model for valuing the contribution of digital water meters to sustainability objectives.

Water security is an issue across the world as communities face ageing infrastructure, population increases and climate change. The application of digital water metering (DWM) to properties has had a demonstrable impact on water savings at the property and network levels, on efficiencies within water utilities, as well as on improvements to customer satisfaction scores. Gathering and processing near-real-time water usage data is very important for both end-users and utilities, as well as demand and supply management planning. The potential contribution of DWM to the three pillars of water sustainability (environmental, economic development and social equity) is often overlooked. In Australia and other jurisdictions water utilities are facing up to the challenge of climate change. However, business cases promoting DWM are often unsuccessful because the benefit side falls short of the cost side. This study sought to identify possible DWM benefits not previously considered through an extensive review of academic and industry literature, and then to view those benefits through the lens of sustainability. The 77 identified benefits of DWM were catalogued and a taxonomy was created. The study elicited the opinions of experts, before quantifying them, thus identifying two distinct contexts of benefit value; subsequently, it surveyed the views of customers and developed a stochastic model of benefit value. The model, named DWM360, was applied to the project data of a large metropolitan water utility in Australia to model their DWM proposal for cost savings, contribution to sustainability and uplift in customer satisfaction. This paper presents a novel focus on how the benefits of DWM assist water sustainability. It considers differing social norms that impact consumer acceptance of changes in metering and water charges. The study will be of interest to researchers as well as practitioners looking to identify sustainability aspects of DWM.

Evaluating coral reef ecosystem services outcomes from climate change adaptation strategies using integrative system dynamics.

Coral reef ecosystems provide a broad spectrum of essential ecological, economic and cultural services for Small Island Developing State (SIDS) communities. However, coral reef communities are increasingly threatened by the adverse impacts of human activities at both global and local scales. This study aims to develop an integrated dynamic assessment framework to evaluate coral reef conditions under different adaptation and climate change scenarios, and their consequential economic impacts in the small island community of Port Resolution on Tanna Island in Vanuatu. Our assessment framework follows a sequential multilayered modelling approach that uses System Dynamics (SD) coupled with Bayesian Network (BN) modelling to deal with the complexity and dynamicity of socioeconomic and environmental systems, and impacts from trans-discipline variables. The BN incorporated existing data and expert knowledge to project the future conditions of coral reefs under different scenario settings, and to parametrise and quantify the SD model where the existing data and information was insufficient. The SD was then used to simulate the dynamic relationship between coral reef condition and the economic benefits derived from its ecosystem services under different climate change (i.e. RCPs) and management scenarios through to 2070. Our findings show that sustainable community-based conservation management strategies are key to preserving the flow of coral reef ecosystem services under RCP 2.6 and 6.0. Importantly, we demonstrate that the implementation of an integrated portfolio of management strategies better protects ecosystem services provided by coral reefs and maximises the total economic benefits achieved over the long-term despite a temporary and short-term economic loss due to high initial capital investments and income reduction due to fishing and tourism restrictions.

Advanced household profiling using digital water meters.

Advanced householder profiling using digital water metering data analytics has been acknowledged as a core strategy for promoting water conservation because of its ability to provide near real-time feedback to customers and instil long-term conservation behaviours. Customer profiling based on household water consumption data collected through digital water meters helps to identify the water consumption patterns and habits of customers. This study employed advanced customer profiling techniques adapted from the machine learning research domain to analyse high-resolution data collected from residential digital water meters. Data analytics techniques were applied on already disaggregated end-use water consumption data (e.g., shower and taps) for creating in-depth customer profiling at various intervals (e.g., 15, 30, and 60 min). The developed user profiling approach has some learning functionality as it can ascertain and accommodate changing behaviours of residential customers. The developed advanced user profiling technique was shown to be beneficial since it identified residential customer behaviours that were previously unseen. Furthermore, the technique can identify and address novel changes in behaviours, which is an important feature for promoting and sustaining long-term water conservation behaviours. The research has implications for researchers in data analytics and water demand management, and also for practitioners and government policy advisors seeking to conserve valuable potable-water resources.

Spatial Bayesian Network for predicting sea level rise induced coastal erosion in a small Pacific Island.

An integrated approach combining Bayesian Network with GIS was developed for making a probabilistic prediction of sea level rise induced coastal erosion and assessing the implications of adaptation measures. The Bayesian Network integrates extensive qualitative and quantitative information into a single probabilistic model while GIS explicitly deals with spatial data for inputting, storing, analysing and mapping. The integration of the Bayesian Network with GIS using a cell-by-cell comparison technique (aka map algebra) provides a new tool to perform the probabilistic spatial analysis. The spatial Bayesian Network was utilised for predicting coastal erosion scenarios at the case study location of Tanna Island, Vanuatu in the South Pacific. Based on the Bayesian Network model, a rate of the island shoreline change was predicted probabilistically for each shoreline segment, which was transferred into GIS for visualisation purposes. The spatial distribution of shoreline change prediction results for various sea level rise scenarios was mapped. The outcomes of this work support risk-based adaptation planning and will be further developed to enable the incorporation of high resolution coastal process models, thereby supporting localised land use planning decisions.

Zebrafish as a model to study neuroblastoma development.

Neuroblastoma is a pediatric solid tumor arising from embryonic neural crest progenitor cells that normally generate the peripheral sympathetic nervous system. As such, the location of neuroblastoma tumors is correlated with the distribution of major post-ganglionic clusters throughout the sympathetic chain, with the highest incidence in the adrenal medulla or lumbar sympathetic ganglia (~65%). Neuroblastoma is an enigmatic tumor that can spontaneously regress with minimal treatment or become highly metastatic and develop resistance to aggressive treatments, including radiation and high-dose chemotherapy. Age of diagnosis, stage of disease and cellular and genetic features often predict whether the tumor will regress or advance to metastatic disease. Recent efforts using molecular and genomic technologies have allowed more accurate stratification of patients into low-, intermediate- and high-risk categories, thereby allowing for minimal intervention in low-risk patients and providing potential new therapeutic targets, such as the ALK receptor tyrosine kinase, for high-risk or relapsed patients. Despite these advances, the overall survival of high-risk neuroblastoma patients is still less than 50%. Furthermore, next-generation sequencing has revealed that almost two-thirds of neuroblastoma tumors do not contain obvious pathogenic mutations, suggesting that epigenetic mechanisms and/or a perturbed cellular microenvironment may heavily influence neuroblastoma development. Understanding the mechanisms that drive neuroblastoma, therefore, will likely require a combination of genomic, developmental and cancer biology approaches in whole animal systems. In this review, we discuss the contributions of zebrafish research to our understanding of neuroblastoma pathogenesis as well as the potential for this model system to accelerate the identification of more effective therapies for high-risk neuroblastoma patients in the future.

Fascin1-dependent Filopodia are required for directional migration of a subset of neural crest cells.

Directional migration of neural crest (NC) cells is essential for patterning the vertebrate embryo, including the craniofacial skeleton. Extensive filopodial protrusions in NC cells are thought to sense chemo-attractive/repulsive signals that provide directionality. To test this hypothesis, we generated null mutations in zebrafish fascin1a (fscn1a), which encodes an actin-bundling protein required for filopodia formation. Homozygous fscn1a zygotic null mutants have normal NC filopodia due to unexpected stability of maternal Fscn1a protein throughout NC development and into juvenile stages. In contrast, maternal/zygotic fscn1a null mutant embryos (fscn1a MZ) have severe loss of NC filopodia. However, only a subset of NC streams display migration defects, associated with selective loss of craniofacial elements and peripheral neurons. We also show that fscn1a-dependent NC migration functions through cxcr4a/cxcl12b chemokine signaling to ensure the fidelity of directional cell migration. These data show that fscn1a-dependent filopodia are required in a subset of NC cells to promote cell migration and NC derivative formation, and that perdurance of long-lived maternal proteins can mask essential zygotic gene functions during NC development.

Evaluating a novel tiered scarcity adjusted water budget and pricing structure using a holistic systems modelling approach.

Population growth, coupled with declining water availability and changes in climatic conditions underline the need for sustainable and responsive water management instruments. Supply augmentation and demand management are the two main strategies used by water utilities. Water demand management has long been acknowledged as a least-cost strategy to maintain water security. This can be achieved in a variety of ways, including: i) educating consumers to limit their water use; ii) imposing restrictions/penalties; iii) using smart and/or efficient technologies; and iv) pricing mechanisms. Changing water consumption behaviours through pricing or restrictions is challenging as it introduces more social and political issues into the already complex water resources management process. This paper employs a participatory systems modelling approach for: (1) evaluating various forms of a proposed tiered scarcity adjusted water budget and pricing structure, and (2) comparing scenario outcomes against the traditional restriction policy regime. System dynamics modelling was applied since it can explicitly account for the feedbacks, interdependencies, and non-linear relations that inherently characterise the water tariff (price)-demand-revenue system. A combination of empirical water use data, billing data and customer feedback on future projected water bills facilitated the assessment of the suitability and likelihood of the adoption of scarcity-driven tariff options for a medium-sized city within Queensland, Australia. Results showed that the tiered scarcity adjusted water budget and pricing structure presented was preferable to restrictions since it could maintain water security more equitably with the lowest overall long-run marginal cost.

Distinct neuroblastoma-associated alterations of PHOX2B impair sympathetic neuronal differentiation in zebrafish models.

Heterozygous germline mutations and deletions in PHOX2B, a key regulator of autonomic neuron development, predispose to neuroblastoma, a tumor of the peripheral sympathetic nervous system. To gain insight into the oncogenic mechanisms engaged by these changes, we used zebrafish models to study the functional consequences of aberrant PHOX2B expression in the cells of the developing sympathetic nervous system. Allelic deficiency, modeled by phox2b morpholino knockdown, led to a decrease in the terminal differentiation markers th and dbh in sympathetic ganglion cells. The same effect was seen on overexpression of two distinct neuroblastoma-associated frameshift mutations, 676delG and K155X - but not the R100L missense mutation - in the presence of endogenous Phox2b, pointing to their dominant-negative effects. We demonstrate that Phox2b is capable of regulating itself as well as ascl1, and that phox2b deficiency uncouples this autoregulatory mechanism, leading to inhibition of sympathetic neuron differentiation. This effect on terminal differentiation is associated with an increased number of phox2b(+), ascl1(+), elavl3(-) cells that respond poorly to retinoic acid. These findings suggest that a reduced dosage of PHOX2B during development, through either a heterozygous deletion or dominant-negative mutation, imposes a block in the differentiation of sympathetic neuronal precursors, resulting in a cell population that is likely to be susceptible to secondary transforming events.

Ccdc94 protects cells from ionizing radiation by inhibiting the expression of p53.

DNA double-strand breaks (DSBs) represent one of the most deleterious forms of DNA damage to a cell. In cancer therapy, induction of cell death by DNA DSBs by ionizing radiation (IR) and certain chemotherapies is thought to mediate the successful elimination of cancer cells. However, cancer cells often evolve to evade the cytotoxicity induced by DNA DSBs, thereby forming the basis for treatment resistance. As such, a better understanding of the DSB DNA damage response (DSB-DDR) pathway will facilitate the design of more effective strategies to overcome chemo- and radioresistance. To identify novel mechanisms that protect cells from the cytotoxic effects of DNA DSBs, we performed a forward genetic screen in zebrafish for recessive mutations that enhance the IR-induced apoptotic response. Here, we describe radiosensitizing mutation 7 (rs7), which causes a severe sensitivity of zebrafish embryonic neurons to IR-induced apoptosis and is required for the proper development of the central nervous system. The rs7 mutation disrupts the coding sequence of ccdc94, a highly conserved gene that has no previous links to the DSB-DDR pathway. We demonstrate that Ccdc94 is a functional member of the Prp19 complex and that genetic knockdown of core members of this complex causes increased sensitivity to IR-induced apoptosis. We further show that Ccdc94 and the Prp19 complex protect cells from IR-induced apoptosis by repressing the expression of p53 mRNA. In summary, we have identified a new gene regulating a dosage-sensitive response to DNA DSBs during embryonic development. Future studies in human cancer cells will determine whether pharmacological inactivation of CCDC94 reduces the threshold of the cancer cell apoptotic response.

A simple and scalable zebrafish model of Sonic hedgehog medulloblastoma.

Medulloblastoma (MB) is the most common malignant brain tumor in children and is stratified into three major subgroups. The Sonic hedgehog (SHH) subgroup represents ∼30% of all MB cases and has significant survival disparity depending upon TP53 status. Here, we describe a zebrafish model of SHH MB using CRISPR to create mutant ptch1, the primary genetic driver of human SHH MB. In these animals, tumors rapidly arise in the cerebellum and resemble human SHH MB by histology and comparative onco-genomics. Similar to human patients, MB tumors with loss of both ptch1 and tp53 have aggressive tumor histology and significantly worse survival outcomes. The simplicity and scalability of the ptch1-crispant MB model makes it highly amenable to CRISPR-based genome-editing screens to identify genes required for SHH MB tumor formation in vivo, and here we identify the gene encoding Grk3 kinase as one such target.

A Simple and Scalable Zebrafish Model of Sonic Hedgehog Medulloblastoma.

Medulloblastoma (MB) is the most common malignant brain tumor in children and is stratified into three major subgroups. The Sonic hedgehog (SHH) subgroup represents ~30% of all MB cases and has significant survival disparity depending upon TP53 status. Here, we describe the first zebrafish model of SHH MB using CRISPR to mutate ptch1, the primary genetic driver in human SHH MB. These tumors rapidly arise adjacent to the valvula cerebelli and resemble human SHH MB by histology and comparative genomics. In addition, ptch1-deficient MB tumors with loss of tp53 have aggressive tumor histology and significantly worse survival outcomes, comparable to human patients. The simplicity and scalability of the ptch1 MB model makes it highly amenable to CRISPR-based genome editing screens to identify genes required for SHH MB tumor formation in vivo, and here we identify the grk3 kinase as one such target.

cpsf1 is required for definitive HSC survival in zebrafish.

A comprehensive understanding of the genes and pathways regulating hematopoiesis is needed to identify genes causally related to bone marrow failure syndromes, myelodysplastic syndromes, and hematopoietic neoplasms. To identify novel genes involved in hematopoiesis, we performed an ethyl-nitrosourea mutagenesis screen in zebrafish (Danio rerio) to search for mutants with defective definitive hematopoiesis. We report the recovery and analysis of the grechetto mutant, which harbors an inactivating mutation in cleavage and polyadenylation specificity factor 1 (cpsf1), a gene ubiquitously expressed and required for 3' untranslated region processing of a subset of pre-mRNAs. grechetto mutants undergo normal primitive hematopoiesis and specify appropriate numbers of definitive HSCs at 36 hours postfertilization. However, when HSCs migrate to the caudal hematopoietic tissue at 3 days postfertilization, their numbers start decreasing as a result of apoptotic cell death. Consistent with Cpsf1 function, c-myb:EGFP(+) cells in grechetto mutants also show defective polyadenylation of snrnp70, a gene required for HSC development. By 5 days postfertilization, definitive hematopoiesis is compromised and severely decreased blood cell numbers are observed across the myeloid, erythroid, and lymphoid cell lineages. These studies show that cpsf1 is essential for HSC survival and differentiation in caudal hematopoietic tissue.

An experimental test of voluntary strategies to promote urban water demand management.

In light of the current and future threats to global water security the current research focuses on trialing interventions to promote urban water conservation. We report an experimental study designed to test the long-term impact of three different interventions on household water consumption in South East Queensland. Participants from 221 households were recruited and completed an initial survey, and their houses were fitted with smart water meters which measured total water usage at 5 s intervals. Households were allocated into one of four conditions: a control group and three interventions groups (water saving information alone, information plus a descriptive norm manipulation, and information plus tailored end-user feedback). The study is the first to use smart water metering technology as a tool for behaviour change as well as a way to test the effectiveness of demand management interventions. Growth curve modelling revealed that compared to the control, the three intervention groups all showed reduced levels of household consumption (an average reduction of 11.3 L per person per day) over the course of the interventions, and for some months afterwards. All interventions led to significant water savings, but long-term household usage data showed that in all cases, the reduction in water use resulting from the interventions eventually dissipated, with water consumption returning to pre-intervention levels after approximately 12 months. Implications for water demand management programs are discussed.

Towards nutrient neutrality: A review of agricultural runoff mitigation strategies and the development of a decision-making framework.

Nutrient runoff from agriculture practices poses a significant risk to waterway health and can have long-lasting and complex implications for the environment, ecosystems, and the human population. Consequently, a systematic quantitative literature review (SQLR) was conducted to identify different nutrient runoff mitigation strategies (NRMS) that are currently used globally to prevent or remediate environmental damage from excessive agricultural fertilisation. Empirical data on the outcomes from various NRMS from the reviewed studies were used to evaluate the strategies based on environmental benefit, implementation cost, and practicality perspectives. An overall assessment of the feasibility of NRMS was determined, and a macro-level assessment of the reported barriers preventing the widespread implementation of NRMS was provided. Identified research gaps and issues included a dearth of literature covering nutrient runoff mitigation, scepticism from agricultural landowners to voluntarily adopt policy without substantial incentives, and a general lack of cost/benefit analyses, including an understanding of the uncertainty associated with NRMS that can inform decision-makers about effective and efficient strategies for different site situations. Synthesis of SQLR data facilitated the development of a comprehensive nutrient runoff decision-making framework which addresses present limitations and provides site-specific NRMS recommendations for policymakers to implement.

The scaffolding function of LSD1/KDM1A reinforces a negative feedback loop to repress stem cell gene expression during primitive hematopoiesis.

Lsd1/Kdm1a functions both as a histone demethylase enzyme and as a scaffold for assembling chromatin modifier and transcription factor complexes to regulate gene expression. The relative contributions of Lsd1's demethylase and scaffolding functions during embryogenesis are not known. Here, we analyze two independent zebrafish lsd1/kdm1a mutant lines and show Lsd1 is required to repress primitive hematopoietic stem cell gene expression. Lsd1 rescue constructs containing point mutations that selectively abrogate its demethylase or scaffolding capacity demonstrate the scaffolding function of Lsd1, not its demethylase activity, is required for repression of gene expression in vivo. Lsd1's SNAG-binding domain mediates its scaffolding function and reinforces a negative feedback loop to repress the expression of SNAG-domain-containing genes during embryogenesis, including gfi1 and snai1/2. Our findings reveal a model in which the SNAG-binding and scaffolding function of Lsd1, and its associated negative feedback loop, provide transient and reversible regulation of gene expression during hematopoietic development.