Cell and Developmental Biology Commons^™

Behavioral Plasticity Of Audiovisual Perception: Rapid Recalibration Of Temporal Sensitivity But Not Perceptual Binding Following Adult-Onset Hearing Loss, Ashley L. Schormans, Brian L. Allaman

Anatomy and Cell Biology Publications

The ability to accurately integrate or bind stimuli from more than one sensory modality is highly dependent on the features of the stimuli, such as their intensity and relative timing. Previous studies have demonstrated that the ability to perceptually bind stimuli is impaired in various clinical conditions such as autism, dyslexia, schizophrenia, as well as aging. However, it remains unknown if adult-onset hearing loss, separate from aging, influences audiovisual temporal acuity. In the present study, rats were trained using appetitive operant conditioning to perform an audiovisual temporal order judgment (TOJ) task or synchrony judgment (SJ) task in order to investigate …

Implementing The Proclamation Of Stroke And Potentially Preventable Dementias, Vladimir Hachinski, Detlev Ganten, Daniel Lackland, Reinhold Kreutz, Konstantinos Tsioufis, Werner Hacke

Anatomy and Cell Biology Publications

Brain health plays a central role in wellbeing and in the management of chronic diseases. Stroke and dementia pose the two greatest threats to brain health, but recent developments suggest the possibility that preventing stroke may also prevent some dementias: 1. A large population study showed a 32% decrease in the incidence of stroke and a concomitant 7% reduction in the incidence of dementia; 2. Treatment of atrial fibrillation resulted not only in stroke reduction, but a 48% decrease in dementia; 3. A hypothesis free analyses has shown that the first phase of Alzheimer disease involves vascular dysregulation, opening the …

Altered Auditory Processing, Filtering, And Reactivity N The Cntnap2 Knock-Out Rat Model For Neurodevelopmental Disorders, Kaela E. Scott, Ashley L. Schormans, Katharine Y. Pacoli, Cleusa De Oliveria, Brian L. Allman, Susanne Schmid

Anatomy and Cell Biology Publications

Sensory processing, and auditory processing in particular, is altered in individuals with neurodevelopmental disorders such as autism spectrum disorders (ASDs). The typical maturation of the auditory system is perturbed in these individuals during early development, which may underlie altered auditory reactivity that persists in later life. Of the many genes that regulate the auditory system development, loss-of-function mutations in the CNTNAP2 gene are strongly associated with language processing deficits and ASD. Therefore, using a novel Cntnap2 knock-out rat model, we tested the impact of Cntnap2 loss on auditory processing, filtering, and reactivity throughout development and young adulthood in male and …

The Role Of Cholinergic Midbrain Neurons In Startle And Prepulse Inhibition, Erin Azzopardi, Andrea G. Louttit, Cleusa Deoliveira, Steven R, Laviolette, Susanne Schmid

Anatomy and Cell Biology Publications

One of the two major cholinergic centers of the mammalian brain is located in the midbrain, i.e., the pedunculopontine tegmentum (PPTg) and the adjacent laterodorsal tegmentum. These cholinergic neurons have been shown to be important for e.g., arousal, reward associations, and sleep. They also have been suggested to mediate sensorimotor gating, measured as prepulse inhibition of startle (PPI). PPI disruptions are a hallmark of schizophrenia and are observed in various other psychiatric disorders, where they are associated with, and often predictive of, other cognitive symptoms. PPI has been proposed to be mediated by a short midbrain circuitry including inhibitory cholinergic …

Everolimus In Advanced Breast Cancer: A Systematic Review And Meta-Analysis, J Raphael, C Lefebvre, A Allan, J Helou, G Boldt, T Vandenberg

Anatomy and Cell Biology Publications

No abstract provided.

Air Pollution: A Silent Common Killer For Stroke And Dementia, Mahmoud R. Azarpazhooh, Vladimir Hachinski

Anatomy and Cell Biology Publications

No abstract provided.

Immune Checkpoints In Cancer Treatment, Matthew A. Cherubino

Student Publications

Despite the human immune system, cancer thrives in an extremely hostile environment. Cancer is the second most common cause of death in the U.S. with about 600,000 deaths every year, and cancer is expected to surpass heart disease as the most common cause of death in the U.S. Immune checkpoint inhibitors are a novel and promising therapeutic for treating cancer in its late stages.

Membrane Associated Collagen Xiii Promotes Cancer Metastasis And Enhances Anoikis Resistance, Hui Zhang, Tricia Fredericks, Gaofeng Xiong, Yifei Qi, Piotr G. Rychahou, Jia-Da Li, Taina Pihlajaniemi, Wei Xu, Ren Xu

Markey Cancer Center Faculty Publications

Background: Increased collagen expression and deposition are associated with cancer progression and poor prognosis in breast cancer patients. However, function and regulation of membrane-associated collagen in breast cancer have not been determined. Collagen XIII is a type II transmembrane protein within the collagen superfamily. Experiments in tissue culture and knockout mouse models show that collagen XIII is involved in cell adhesion and differentiation of certain cell types. In the present study, we determined roles of collagen XIII in breast cancer progression and metastasis.

Methods: We analyzed the association of collagen XIII expression with breast cancer development and metastasis using published …

Comprehensive Evaluation Of Treatment And Outcomes Of Low-Grade Diffuse Gliomas, Catherine R. Garcia, Stacey A. Slone, Thomas A. Pittman, William H. St. Clair, Donita D. Lightner, John L. Villano

Markey Cancer Center Faculty Publications

Background

Low-grade gliomas affect younger adults and carry a favorable prognosis. They include a variety of biological features affecting clinical behavior and treatment. Having no guidelines on treatment established, we aim to describe clinical and treatment patterns of low-grade gliomas across the largest cancer database in the United States.

Methods

We analyzed the National Cancer Database from 2004 to 2015, for adult patients with a diagnosis of World Health Organization grade II diffuse glioma.

Results

We analyzed 13,621 cases with median age of 41 years. Over 56% were male, 88.4% were white, 6.1% were black, and 7.6% Hispanic. The most …

Iron-Dependent Cleavage Of Ribosomal Rna During Oxidative Stress In The Yeast Saccharomyces Cerevisiae, Jessica A Zinskie, Arnab Ghosh, Brandon M Trainor, Daniel Shedlovskiy, Dimitri G Pestov, Natalia Shcherbik

Rowan-Virtua School of Osteopathic Medicine Departmental Research

Stress-induced strand breaks in rRNA have been observed in many organisms, but the mechanisms by which they originate are not well-understood. Here we show that a chemical rather than an enzymatic mechanism initiates rRNA cleavages during oxidative stress in yeast (Saccharomyces cerevisiae). We used cells lacking the mitochondrial glutaredoxin Grx5 to demonstrate that oxidant-induced cleavage formation in 25S rRNA correlates with intracellular iron levels. Sequestering free iron by chemical or genetic means decreased the extent of rRNA degradation and relieved the hypersensitivity of grx5Δ cells to the oxidants. Importantly, subjecting purified ribosomes to an in vitro iron/ascorbate …

Glutathione De Novo Synthesis But Not Recycling Process Coordinates With Glutamine Catabolism To Control Redox Homeostasis And Directs Murine T Cell Differentiation, Gaojian Lian, J. N. Rashida Gnanaprakasam, Tingting Wang, Ruohan Wu, Xuyong Chen, Lingling Liu, Yuqing Shen, Mao Yang, Jun Yang, Ying Chen, Vasilis Vasiliou, Teresa A. Cassel, Douglas R. Green, Yusen Liu, Teresa W. -M. Fan, Ruoning Wang

Toxicology and Cancer Biology Faculty Publications

Upon antigen stimulation, T lymphocytes undergo dramatic changes in metabolism to fulfill the bioenergetic, biosynthetic and redox demands of proliferation and differentiation. Glutathione (GSH) plays an essential role in controlling redox balance and cell fate. While GSH can be recycled from Glutathione disulfide (GSSG), the inhibition of this recycling pathway does not impact GSH content and murine T cell fate. By contrast, the inhibition of the de novo synthesis of GSH, by deleting either the catalytic (Gclc) or the modifier (Gclm) subunit of glutamate–cysteine ligase (Gcl), dampens intracellular GSH, increases ROS, and impact T cell differentiation. Moreover, the inhibition of …

Susceptibility Genes To Plant Viruses, Hernan Garcia-Ruiz

Nebraska Center for Virology: Faculty Publications

Plant viruses use cellular factors and resources to replicate and move. Plants respond to viral infection by several mechanisms, including innate immunity, autophagy, and gene silencing, that viruses must evade or suppress. Thus, the establishment of infection is genetically determined by the availability of host factors necessary for virus replication and movement and by the balance between plant defense and viral suppression of defense responses. Host factors may have antiviral or proviral activities. Proviral factors condition susceptibility to viruses by participating in processes essential to the virus. Here, we review current advances in the identification and characterization of host factors …

Escherichia Coli Itat Is A Type Ii Toxin That Inhibits Translation By Acetylating Isoleucyl-Trnaile, Brendan Wilcox, Ilya Osterman, Marina Serebryakova, Dmitry Lukyanov, Ekaterina Komarova, Bridget Gollan, Natalia Morozova, Yuri I Wolf, Kira S Makarova, Sophie Helaine, Petr Sergiev, Svetlana Dubiley, Sergei Borukhov, Konstantin Severinov

Rowan-Virtua School of Osteopathic Medicine Departmental Research

Prokaryotic toxin-antitoxin (TA) modules are highly abundant and are involved in stress response and drug tolerance. The most common type II TA modules consist of two interacting proteins. The type II toxins are diverse enzymes targeting various essential intracellular targets. The antitoxin binds to cognate toxin and inhibits its function. Recently, TA modules whose toxins are GNAT-family acetyltransferases were described. For two such systems, the target of acetylation was shown to be aminoacyl-tRNA: the TacT toxin targets aminoacylated elongator tRNAs, while AtaT targets the amino acid moiety of initiating tRNAMet. We show that the itaRT gene pair from Escherichia coli …

Comparative Proteomic Analyses Of Human Adipose Extracellular Matrices Decellularized Using Alternative Procedures, Caasy Porch-Thomas, Jie Li, Fabiana Zanata, Elizabeth C. Martin, Nicholas Pashos, Kaylynn Genemaras, Nicholas J. Poche, Nicholas P. Totaro, Melyssa R. Bratton, Dina Gaupp, Trivia Frazier, Xiying Wu, Lydia Masako Ferreira, Weidong Tian, Guangdi Wang, Bruce A. Bunnell, Lauren Flynn, Daniel Hayes, Jeffrey M. Gimble

Anatomy and Cell Biology Publications

Decellularized human adipose tissue has potential clinical utility as a processed biological scaffold for soft tissue cosmesis, grafting, and reconstruction. Adipose tissue decellularization has been accomplished using enzymatic-, detergent-, and/or solvent-based methods. To examine the hypothesis that distinct decellularization processes may yield scaffolds with differing compositions, the current study employed mass spectrometry to compare the proteomes of human adipose-derived matrices generated through three independent methods combining enzymatic-, detergent-, and/or solvent-based steps. In addition to protein content, bioscaffolds were evaluated for deoxyribose nucleic acid depletion, extracellular matrix composition, and physical structure using optical density, histochemical staining, and scanning electron microscopy. Mass …

Mechanisms Adopted By Dengue-2 Viruses To Induce Autophagy In Mammalian Cells, Sounak Ghosh Roy

Dissertations, Theses, and Capstone Projects

Dengue, the most rapidly spreading flavivirus, threatens to affect almost half of the human global population. We previously showed that dengue-2 protects canine kidney cells (MDCK) from cytotoxic chemicals. We showed, independently, that cell protection, as well as viral replication and maturation, are positively regulated by PI3K-dependent autophagy. However, we had not identified the specific pathway that induces autophagy in infected cells. The current study explores the role of a specific branch of the endoplasmic reticulum (ER) stress-mediated Unfolded Protein Response (UPR), the PERK/eIF2α/ATF4 pathway in the induction of autophagy by …

Strategies Involving The Food-Derived Agent Curcumin To Eliminate Brain Cancer, Sumit Mukherjee

Dissertations, Theses, and Capstone Projects

Glioblastoma (GBM) is one of the most deadly forms of cancer with a mean 5-year survival rate of ≤5%. We have used the non-invasive strategy of long-term intranasal (IN) delivery of a glioblastoma-directed adduct of curcumin (CC), CC-CD68Ab, into the brain of murine GBM cell line GL261-implanted mice to study the therapeutic effect of CC on GBM remission. The treatment caused GBM tumor remission in 50% of GL261-implanted GBM mice. A similar rescue rate (60%) was also achieved through long-term intraperitoneal (i.p) infusion of a highly bioavailable phosphotidylcholine (PC)-encapsulated formulation of CC, Curcumin Phytosome Meriva (CCP), into the GL261-implanted GBM …

Recombinant Human Proteoglycan-4 Reduces Phagocytosis Of Urate Crystals And Downstream Nuclear Factor Kappa B And Inflammasome Activation And Production Of Cytokines And Chemokines In Human And Murine Macrophages, Marwa Qadri, Gregory D. Jay, Ling X. Zhang, Wendy Wong, Anthony M. Reginato, Changqi Sun, Tannin A. Schmidt

Pharmacy Faculty Articles and Research

Microbial biofilms are organized communities of cells that are associated with a wide spectrum of resistant and chronic infections that lead to the treatment failure. Accordingly, there is an urgent demand to create novel effective therapeutic drugs that can inhibit biofilm formation with new mechanisms of action to surmount the current escalating resistance. In this study, in silico hybrid model was utilized to develop three novel short linear peptides (4, 5, and 6) with potential biofilm inhibiting activities (scores > 1.0). The peptides were composed of cationic and hydrophobic residues. They were synthesized using solid-phase strategy. Synthesized peptides were purified and …

App21 Transgenic Rats Develop Age-Dependent Cognitive Impairment And Microglia Accumulation Within White Matter Tracts, Nina Weishaupt, Qingfan Liu, Sheojung Shin, Ramandeep Singh, Yuksel Agca, Cansu Agca, Vladimir Hachinski, Shawn Narain Whitehead

Anatomy and Cell Biology Publications

Background: Most of the animal models commonly used for preclinical research into Alzheimer's disease (AD) largely fail to address the pathophysiology, including the impact of known risk factors, of the widely diagnosed sporadic form of the disease. Here, we use a transgenic rat (APP21) that does not develop AD-like pathology spontaneously with age, but does develop pathology following vascular stress. To further the potential of this novel rat model as a much-needed pre-clinical animal model of sporadic AD, we characterize APP21 transgenic rats behaviorally and histologically up to 19 months of age. Methods: The open field test was used as …

Ubiquitin Regulation: The Histone Modifying Enzyme's Story, Jianlin Wang, Zhaoping Qiu, Yadi Wu

Pharmacology and Nutritional Sciences Faculty Publications

Histone post-translational modifications influence many fundamental cellular events by regulating chromatin structure and gene transcriptional activity. These modifications are highly dynamic and tightly controlled, with many enzymes devoted to the addition and removal of these modifications. Interestingly, these modifying enzymes are themselves fine-tuned and precisely regulated at the level of protein turnover by ubiquitin-proteasomal processing. Here, we focus on recent progress centered on the mechanisms regulating ubiquitination of histone modifying enzymes, including ubiquitin proteasomal degradation and the reverse process of deubiquitination. We will also discuss the potential pathophysiological significance of these processes.

N-Terminal Domain Of Human Uracil Dna Glycosylase (Hung2) Promotes Targeting To Uracil Sites Adjacent To Ssdna-Dsdna Junctions, Brian P Weiser, Gaddiel Rodriguez, Philip A Cole, James T Stivers

Rowan-Virtua School of Osteopathic Medicine Departmental Research

The N-terminal domain (NTD) of nuclear human uracil DNA glycosylase (hUNG2) assists in targeting hUNG2 to replication forks through specific interactions with replication protein A (RPA). Here, we explored hUNG2 activity in the presence and absence of RPA using substrates with ssDNA-dsDNA junctions that mimic structural features of the replication fork and transcriptional R-loops. We find that when RPA is tightly bound to the ssDNA overhang of junction DNA substrates, base excision by hUNG2 is strongly biased toward uracils located 21 bp or less from the ssDNA-dsDNA junction. In the absence of RPA, hUNG2 still showed an 8-fold excision bias …

Direct Quantification Of Deubiquitinating Enzyme Activity In Single Intact Cells, Nora Safabakhsh

LSU Doctoral Dissertations

Challenges in drug efficacy occur during the treatment of most types of cancer due to the heterogeneity of the tumor microenvironment. This has led to the development of personalized medicine. Due to the clinical success of the proteasome inhibitors Bortezomib and Carfilzomib in treatment of multiple myeloma, interest has shifted towards molecularly-targeted chemotherapeutics for ubiquitin-proteasome system (UPS). Deubiquitinating enzymes (DUBs) are an essential part of this pathway which have been found to promote Bortezomib resistance in multiple myeloma patients. Unfortunately, there is a lack of specific, high throughput biochemical assays to characterize DUB activity in patient samples before and after …

Uplc-Ms/Ms Analysis Of Dextromethorphan-O-Demethylation Kinetics In Rat Brain Microsomes, Barent N. Dubois, Reza Mehvar

Pharmacy Faculty Articles and Research

Formation of dextrorphan (DXT) from dextromethorphan (DXM) has been widely used to assess cytochrome P450 2D (CYP2D) activity. Additionally, the kinetics of CYP2D activity have been well characterized in the liver microsomes. However, studies in brain microsomes are limited due to the lower microsomal content and abundance of CYP2D in the brain relative to the liver. In the present study, we developed a micro-scale enzymatic incubation method, coupled with a sensitive UPLC-MS/MS assay for the quantitation of the rate of DXT formation from DXM in brain microsomes. Rat brain microsomes were incubated with different concentrations of DXM for various times. …

Na/K-Atpase Y260 Phosphorylation-Mediated Src Regulation In Control Of Aerobic Glycolysis And Tumor Growth, Moumita Banerjee, Xiaoyu Cui, Zhichuan Li, Hui Yu, Liquan Cai, Xuelian Jia, Daheng He, Chi Wang, Tianyan Gao, Zijian Xie

Markey Cancer Center Faculty Publications

We report here the identification of α1 Na/K-ATPase as a major regulator of the proto-oncogene Src kinase and the role of this regulation in control of Warburg effect and tumor growth. Specifically, we discovered Y260 in α1 Na/K-ATPase as a Src-specific phosphorylation and binding site and that Y260 phosphorylation is required for Src-mediated signal transduction in response to a number of stimuli including EGF. As such, it enables a dynamic control of aerobic glycolysis. However, such regulation appears to be lost or attenuated in human cancers as the expression of Na/K-ATPase α1 was significantly decreased in prostate, breast and kidney …

Astromimetics: The Dawn Of A New Era For (Bio)Materials Science?, Vuk Uskoković, Victoria M. Wu

Pharmacy Faculty Articles and Research

Composite, multifunctional fine particles are likely to be at the frontier of materials science in the foreseeable future. Here we present a submicron composite particle that mimics the stratified structure of the Earth by having a zero-valent iron core, a silicate/silicide mantle, and a thin carbonaceous crust resembling the biosphere and its biotic deposits. Particles were formulated in a stable colloidal form and made to interact with various types of healthy and cancer cells in vitro. A selective anticancer activity was observed, promising from the point of view of the intended use of the particles for tumor targeting across the …

Identification Of Susceptibility Pathways For The Role Of Chromosome 15q25.1 In Modifying Lung Cancer Risk, Xuemei Ji, Yohan Bossé, Maria Teresa Landi, Jiang Gui, Xiangjun Xiao, David Qian, Philippe Joubert Joubert, Maxime Lamontagne, Yafang Li, Ivan Gorlov, Mariella De Biasi, Younghun Han, Olga Gorlova, Rayjean J. Hung, Xifeng Wu, James Mckay, Xuchen Zong, Robert Carreras-Torres, David C. Christiani, Neil Caporaso, Mattias Johansson, Geoffrey Liu, Stig E. Bojesen, Loic Le Marchand, Demetrios Albanes, Heike Bickeböller, Melinda C. Aldrich, William S. Bush, Adonina Tardon, Gad Rennert, Susanne M. Arnold

Markey Cancer Center Faculty Publications

Genome-wide association studies (GWAS) identified the chromosome 15q25.1 locus as a leading susceptibility region for lung cancer. However, the pathogenic pathways, through which susceptibility SNPs within chromosome 15q25.1 affects lung cancer risk, have not been explored. We analyzed three cohorts with GWAS data consisting 42,901 individuals and lung expression quantitative trait loci (eQTL) data on 409 individuals to identify and validate the underlying pathways and to investigate the combined effect of genes from the identified susceptibility pathways. The KEGG neuroactive ligand receptor interaction pathway, two Reactome pathways, and 22 Gene Ontology terms were identified and replicated to be significantly associated …

Aged Murine Hematopoietic Stem Cells Drive Aging-Associate Immune Remodeling, Hanna Leins, Medhanie Mulaw, Karina Eiwen, Vadim Sakk, Ying Liang, Michael Denkinger, Hartmut Geiger, Reinhold Schirmbeck

Toxicology and Cancer Biology Faculty Publications

Aging-associated remodeling of the immune system impairs its functional integrity and contributes to increased morbidity and mortality in the elderly. Aging of hematopoietic stem cells (HSCs), from which all cells of the adaptive immune system ultimately originate, might play a crucial role in the remodeling of the aged immune system. We recently reported that aging of HSCs is, in part, driven by elevated activity of the small RhoGTPase Cdc42 and that aged HSCs can be rejuvenated in vitro by inhibition of the elevated Cdc42 activity in aged HSCs with the pharmacological compound CASIN. To study the quality of immune systems …

An Expanded Toolkit For Gene Tagging Based On Mimic And Scarless Crispr Tagging In, David Li-Kroeger, Oguz Kanca, Pei-Tseng Lee, Sierra Cowan, Michael T Lee, Manish Jaiswal, Jose Luis Salazar, Yuchun He, Zhongyuan Zuo, Hugo J Bellen

Faculty, Staff and Students Publications

We generated two new genetic tools to efficiently tag genes in Drosophila. The first, Double Header (DH) utilizes intronic MiMIC/CRIMIC insertions to generate artificial exons for GFP mediated protein trapping or T2A-GAL4 gene trapping in vivo based on Cre recombinase to avoid embryo injections. DH significantly increases integration efficiency compared to previous strategies and faithfully reports the expression pattern of genes and proteins. The second technique targets genes lacking coding introns using a two-step cassette exchange. First, we replace the endogenous gene with an excisable compact dominant marker using CRISPR making a null allele. Second, the insertion is replaced …

Green Tea Polyphenol Epigallocatechin-3-Gallate-Stearate Inhibits The Growth Of Streptococcus Mutans: A Promising New Approach In Caries Prevention, Amy Lynn Melok, Lee Lee, Siti Ayuni Mohamed Yussof, Tinchun Chu

Department of Biology Faculty Scholarship and Creative Works

Streptococcus mutans (S. mutans) is the main etiological bacteria present in the oral cavity that leads to dental caries. All of the S. mutans in the oral cavity form biofilms that adhere to the surfaces of teeth. Dental caries are infections facilitated by the development of biofilm. An esterified derivative of epigallocatechin-3-gallate (EGCG), epigallocatechin-3-gallate-stearate (EGCG-S), was used in this study to assess its ability to inhibit the growth and biofilm formation of S. mutans. The effect of EGCG-S on bacterial growth was evaluated with colony forming units (CFU) and log reduction; biofilm formation was qualitatively determined by Congo red assay, …

Targeting Pro-Inflammatory Function Of Microglia Using Small Molecules To Combat Neurodegeneration, Gabrielle C. Williams, Priya Prakash, Gaurav Chopra

The Summer Undergraduate Research Fellowship (SURF) Symposium

Microglia are the brain’s resident immune cells that are responsible for maintaining homeostasis in healthy conditions. During injury or infection, resting microglia get activated and produce pro-inflammatory cytokines such as IL-1b, IL-1a, IL-6, etc. along with reactive oxygen species like nitric oxide (NO) to combat neuroinflammatory diseases such as Alzheimer’s disease (AD). Inflammation is characterized by the activation of resident-immune cells in the brain called microglia that respond to the eat-me signals released by the toxic amyloid beta peptides as well as the dying neurons in the microenvironment. Recent studies have shown that activated microglia induce neuronal death by secreting …

The Role Of Developmental Timing Regulators In Progenitor Proliferation And Cell Fate Specification During Mammalian Neurogenesis, Jennifer S. Romer-Seibert

Graduate School of Biomedical Sciences Theses and Dissertations

Developmental timing is a key aspect of tissue and organ formation in which distinct cell types are generated through a series of steps from common progenitors. These progenitors undergo specific changes in gene expression that signifies both a distinct progenitor type and developmental time point that thereby specifies a particular cell fate at that stage of development. The nervous system is an important setting for understanding developmental timing because different cell types are produced in a certain order and the switch from stem cells to progenitors requires precise timing and regulation. Notable examples of such regulatory molecules include the RNA-binding …