Browsing by Author "Sarmah, Swapnalee"

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    Another Swim in the Extensive Pool of Zebrafish Research
    (MDPI, 2024-02-29) Marrs, James A.; Sarmah, Swapnalee; Biology, School of Science
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    Effect of Curcuminoids in Turmeric on Developing Zebrafish Treated with Ethanol
    (Office of the Vice Chancellor for Research, 2016-04-08) Connors, Craig; Mohammed, Arooj; Muralidharan, Pooja; Sarmah, Swapnalee; Marrs, James; Marrs, Kathleen A.; Chism, Grady
    This experiment was designed with the intention of determining whether turmeric could act as a rescue agent to prevent or mitigate the extent of Fetal Alcohol Spectrum Disorder (FASD) caused by early ethanol exposure using zebrafish as a model system. A range of turmeric concentrations were made from a stock solution of turmeric dissolved in ethanol (1mg turmeric in 5mL ethanol). The active agents in turmeric are the curcuminoids: Curcumin, Desmethoxycurcumin, and Bisdemethoxycurcumin. The curcuminoids concentration was estimated using liquid chromatography. These agents were present in the turmeric stock solution at the following concentrations: Bisdemethoxycurcumin: 36.6 +/- 0.1 ug/mL, Desmethoxycurcumin: 43.4 +/- 0.1 ug/mL, and Curcumin: 124.1 +/- 0.2 ug/mL. Untreated zebrafish embryos were placed in embryo medium, ethanol treated embryos in 100mM ethanol containing embryo medium, and turmeric co-supplemented medium with differing concentrations of turmeric. Since the turmeric stock solution was dissolved in ethanol, the concentration of ethanol was kept at a constant 100mM ethanol and the amount of turmeric solution added. The concentrations of the test plates were then based on this solution and made to be 100 mM ethanol and 1.16 uM curcuminoids, 100 mM ethanol and 1.74 uM curcuminoids, and 100 mM ethanol and 2.32 uM curcuminoids. The developing embryos were treated with the turmeric solution and/or ethanol during 2-24 hours post fertilization (hpf). These embryos were imaged at 72 hpf and their body length and eye diameter were measured. The embryos supplemented with curcuminoids showed a significant rescue effect on the body length and eye diameter compared to ethanol treated embryos. This indicates that the curcuminoids acted as a rescue agent to reduce the effects that are typical of FASD in developing zebrafish.
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    Effects of GSK3-β Inhibitors on Wnt Signaling in Zebrafish Fin Regeneration: Chemical Biology
    (2014-04-11) Brannick, Angelica; Mahin, Jennifer L.; Farrel, Mark; Curtis, Courtney; Sarmah, Swapnalee; Collins, Kayla; Chu, Shaoyou; Sato, Mas; Sanchez-Felix, Manuel
    In order to develop beneficial drugs for osteoporosis it is important to understand the molecular mechanisms of bone regeneration and define specific regulatory factors. Zebrafish can regenerate damaged tissues, and they prove to be a good model to study bone growth and repair. Previous research showed that GSK3β inhibitor compound at various concentrations and for different treatment periods effectively stimulated fin regeneration. Conducted experiments identified temporal and spatial fluctuations on individual gene markers after GSK3β inhibitor treatment at various concentrations. Recent analyzed data uses the Lilly Research Labs experimental compound LSN 2105786 at 3 nM and 5 nM to stimulate tissue regeneration to determine whether activating Wnt signaling produces cell proliferation and β-catenin translocation to the nucleus for zebrafish bone regeneration. This research has potential to identify mechanism of bone growth and repair, leading to more suitable drugs for patients suffering with osteoporosis.
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    Elf3 deficiency during zebrafish development alters extracellular matrix organization and disrupts tissue morphogenesis
    (PLOS, 2022-11-16) Sarmah, Swapnalee; Hawkins, Matthew R.; Manikandan, Priyadharshini; Farrell, Mark; Marrs , James A.; Biology, School of Science
    E26 transformation specific (ETS) family transcription factors are expressed during embryogenesis and are involved in various cellular processes such as proliferation, migration, differentiation, angiogenesis, apoptosis, and survival of cellular lineages to ensure appropriate development. Dysregulated expression of many of the ETS family members is detected in different cancers. The human ELF3, a member of the ETS family of transcription factors, plays a role in the induction and progression of human cancers is well studied. However, little is known about the role of ELF3 in early development. Here, the zebrafish elf3 was cloned, and its expression was analyzed during zebrafish development. Zebrafish elf3 is maternally deposited. At different developmental stages, elf3 expression was detected in different tissue, mainly neural tissues, endoderm-derived tissues, cartilage, heart, pronephric duct, blood vessels, and notochord. The expression levels were high at the tissue boundaries. Elf3 loss-of-function consequences were examined by using translation blocking antisense morpholino oligonucleotides, and effects were validated using CRISPR/Cas9 knockdown. Elf3-knockdown produced short and bent larvae with notochord, craniofacial cartilage, and fin defects. The extracellular matrix (ECM) in the fin and notochord was disorganized. Neural defects were also observed. Optic nerve fasciculation (bundling) and arborization in the optic tectum were defective in Elf3-morphants, and fragmentation of spinal motor neurons were evident. Dysregulation of genes encoding ECM proteins and matrix metalloprotease (MMP) and disorganization of ECM may play a role in the observed defects in Elf3 morphants. We conclude that zebrafish Elf3 is required for epidermal, mesenchymal, and neural tissue development.
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    Embryonic Ethanol Exposure Affects Early- and Late-Added Cardiac Precursors and Produces Long-Lasting Heart Chamber Defects in Zebrafish
    (MDPI, 2017-12-01) Sarmah, Swapnalee; Marrs, James A.; Biology, School of Science
    Drinking mothers expose their fetuses to ethanol, which produces birth defects: craniofacial defects, cognitive impairment, sensorimotor disabilities and organ deformities, collectively termed as fetal alcohol spectrum disorder (FASD). Various congenital heart defects (CHDs) are present in FASD patients, but the mechanisms of alcohol-induced cardiogenesis defects are not completely understood. This study utilized zebrafish embryos and older larvae to understand FASD-associated CHDs. Ethanol-induced cardiac chamber defects initiated during embryonic cardiogenesis persisted in later zebrafish life. In addition, myocardial damage was recognizable in the ventricle of the larvae that were exposed to ethanol during embryogenesis. Our studies of the pathogenesis revealed that ethanol exposure delayed differentiation of first and second heart fields and reduced the number of early- and late-added cardiomyocytes in the heart. Ethanol exposure also reduced the number of endocardial cells. Together, this study showed that ethanol-induced heart defects were present in late-stage zebrafish larvae. Reduced numbers of cardiomyocytes partly accounts for the ethanol-induced zebrafish heart defects.
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    Embryonic ethanol exposure alters expression of sox2 and other early transcripts in zebrafish, producing gastrulation defects
    (Springer Nature, 2020-03-03) Sarmah, Swapnalee; Srivastava, Rajneesh; McClintick, Jeanette N.; Janga, Sarath C.; Edenberg, Howard J.; Marrs, James A.; Biology, School of Science
    Ethanol exposure during prenatal development causes fetal alcohol spectrum disorder (FASD), the most frequent preventable birth defect and neurodevelopmental disability syndrome. The molecular targets of ethanol toxicity during development are poorly understood. Developmental stages surrounding gastrulation are very sensitive to ethanol exposure. To understand the effects of ethanol on early transcripts during embryogenesis, we treated zebrafish embryos with ethanol during pre-gastrulation period and examined the transcripts by Affymetrix GeneChip microarray before gastrulation. We identified 521 significantly dysregulated genes, including 61 transcription factors in ethanol-exposed embryos. Sox2, the key regulator of pluripotency and early development was significantly reduced. Functional annotation analysis showed enrichment in transcription regulation, embryonic axes patterning, and signaling pathways, including Wnt, Notch and retinoic acid. We identified all potential genomic targets of 25 dysregulated transcription factors and compared their interactions with the ethanol-dysregulated genes. This analysis predicted that Sox2 targeted a large number of ethanol-dysregulated genes. A gene regulatory network analysis showed that many of the dysregulated genes are targeted by multiple transcription factors. Injection of sox2 mRNA partially rescued ethanol-induced gene expression, epiboly and gastrulation defects. Additional studies of this ethanol dysregulated network may identify therapeutic targets that coordinately regulate early development.
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    Embryonic Ethanol Exposure Dysregulates BMP and Notch Signaling, Leading to Persistent Atrio-Ventricular Valve Defects in Zebrafish
    (Plos, 2016-08-24) Sarmah, Swapnalee; Muralidharan, Pooja; Marrs, James A.; Department of Biology, School of Science
    Fetal alcohol spectrum disorder (FASD), birth defects associated with ethanol exposure in utero, includes a wide spectrum of congenital heart defects (CHDs), the most prevalent of which are septal and conotruncal defects. Zebrafish FASD model was used to dissect the mechanisms underlying FASD-associated CHDs. Embryonic ethanol exposure (3–24 hours post fertilization) led to defects in atrio-ventricular (AV) valvulogenesis beginning around 37 hpf, a morphogenetic event that arises long after ethanol withdrawal. Valve leaflets of the control embryos comprised two layers of cells confined at the compact atrio-ventricular canal (AVC). Ethanol treated embryos had extended AVC and valve forming cells were found either as rows of cells spanning the AVC or as unorganized clusters near the AV boundary. Ethanol exposure reduced valve precursors at the AVC, but some ventricular cells in ethanol treated embryos exhibited few characteristics of valve precursors. Late staged larvae and juvenile fish exposed to ethanol during embryonic development had faulty AV valves. Examination of AVC morphogenesis regulatory networks revealed that early ethanol exposure disrupted the Bmp signaling gradient in the heart during valve formation. Bmp signaling was prominent at the AVC in controls, but ethanol-exposed embryos displayed active Bmp signaling throughout the ventricle. Ethanol exposure also led to mislocalization of Notch signaling cells in endocardium during AV valve formation. Normally, highly active Notch signaling cells were organized at the AVC. In ethanol-exposed embryos, highly active Notch signaling cells were dispersed throughout the ventricle. At later stages, ethanol-exposed embryos exhibited reduced Wnt/β-catenin activity at the AVC. We conclude that early embryonic ethanol exposure alters Bmp, Notch and other signaling activities during AVC differentiation leading to faulty valve morphogenesis and valve defects persist in juvenile fish.
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    Ethanol Effects on Early Developmental Stages Studied Using the Zebrafish
    (MDPI, 2022-10-13) Manikandan, Priyadharshini; Sarmah, Swapnalee; Marrs, James A.; Biology, School of Science
    Fetal alcohol spectrum disorder (FASD) results from prenatal ethanol exposure. The zebrafish (Danio rerio) is an outstanding in vivo FASD model. Early development produced the three germ layers and embryonic axes patterning. A critical pluripotency transcriptional gene circuit of sox2, pou5f1 (oct4; recently renamed pou5f3), and nanog maintain potency and self-renewal. Ethanol affects sox2 expression, which functions with pou5f1 to control target gene transcription. Various genes, like elf3, may interact and regulate sox2, and elf3 knockdown affects early development. Downstream of the pluripotency transcriptional circuit, developmental signaling activities regulate morphogenetic cell movements and lineage specification. These activities are also affected by ethanol exposure. Hedgehog signaling is a critical developmental signaling pathway that controls numerous developmental events, including neural axis specification. Sonic hedgehog activities are affected by embryonic ethanol exposure. Activation of sonic hedgehog expression is controlled by TGF-ß family members, Nodal and Bmp, during dorsoventral (DV) embryonic axis establishment. Ethanol may perturb TGF-ß family receptors and signaling activities, including the sonic hedgehog pathway. Significantly, experiments show that activation of sonic hedgehog signaling rescues some embryonic ethanol exposure effects. More research is needed to understand how ethanol affects early developmental signaling and morphogenesis.
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    Ethanol-induced Retinal Defects are Rescued by Retinoic Acid Supplement in Developing Zebrafish Embryos
    (Office of the Vice Chancellor for Research, 2013-04-05) Muralidharan, Pooja; Sarmah, Swapnalee; Marrs, James A.
    Fetal Alcohol Spectrum Disorder (FASD) is caused by prenatal alcohol exposure, producing a spectrum of defects including facial abnormalities, sensory (visual and auditory) deficits, impaired fine motor skills and learning deficits including mental retardation. Our laboratory has used a zebrafish model for FASD that exposes embryos to ethanol during early development (midblastula transition through somitogenesis). Children diagnosed with FASD frequently show severe eye defects ranging from small eyes, underdeveloped optic nerve, and cataract. Zebrafish embryos exposed to ethanol showed defects similar to human eye birth defects. Presence of ethanol affected the differentiation of many retinal cell types including, retinal ganglion cells and photoreceptors. We hypothesize that ethanol may affect retinal patterning by competing with Retinaldehyde dehydrogenase (Raldh), reducing retinoic acid (RA) synthesis and signaling. Co-treatment of embryos with ethanol and 10-9 M RA could rescue the photoreceptor and retinal ganglion cell differentiation defects in the retina. RA plays a crucial role in the dorso-ventral patterning of the retina, and the enzymes involved in RA biosynthesis are expressed in the ventral retina during mid-somitogenesis stage. Our experiments showed that ethanol exposure during that critical time window when Raldh is expressed in the ventral retina causes severe defects in retinal cell specification. No defects were induced by ethanol exposure at the earlier stages. Presence of RA during photoreceptor differentiation could rescue ethanol-induced photoreceptor differentiation defects. Future work will dissect molecular mechanisms underlying ethanol defects, including retinoic acid-mediated eye development mechanisms. Determining the effects of ethanol exposure on retinal morphogenesis and differentiation will help identify potential therapeutic targets for ocular defects in this regrettably frequent birth defect syndrome.
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    Fetal Alcohol Spectrum Disorder (FASD) Associated Neural Defects: Complex Mechanisms and Potential Therapeutic Targets
    (MDPI, 2013-06-19) Muralidharan, Pooja; Sarmah, Swapnalee; Zhou, Feng C.; Marrs, James A.; Biology, School of Science
    Fetal alcohol spectrum disorder (FASD), caused by prenatal alcohol exposure, can result in craniofacial dysmorphism, cognitive impairment, sensory and motor disabilities among other defects. FASD incidences are as high as 2% to 5 % children born in the US, and prevalence is higher in low socioeconomic populations. Despite various mechanisms being proposed to explain the etiology of FASD, the molecular targets of ethanol toxicity during development are unknown. Proposed mechanisms include cell death, cell signaling defects and gene expression changes. More recently, the involvement of several other molecular pathways was explored, including non-coding RNA, epigenetic changes and specific vitamin deficiencies. These various pathways may interact, producing a wide spectrum of consequences. Detailed understanding of these various pathways and their interactions will facilitate the therapeutic target identification, leading to new clinical intervention, which may reduce the incidence and severity of these highly prevalent preventable birth defects. This review discusses manifestations of alcohol exposure on the developing central nervous system, including the neural crest cells and sensory neural placodes, focusing on molecular neurodevelopmental pathways as possible therapeutic targets for prevention or protection.