Developmental Biology Commons^™

Anillin And Dunk: The Conserved And Non-Conserved Players Regulating Myosin Dynamics In Drosophila Cleavage, Jiayang Chen

Dartmouth College Ph.D Dissertations

Cleavage is a common process during early embryogenesis. Similar to conventional cytokinesis, Drosophila cellularization, a unique form of cleavage, requires precise regulation of non-muscle myosin II ("myosin") at cleavage furrows, where myosin forms an interconnected basal array before reorganizing into individual cytokinetic rings. However, how myosin is regulated through both conserved and cellularization-specific mechanisms during this special form of cytokinesis remains unclear.

In my first project, I investigated the molecular mechanisms by which the cellularization-specific zygotic gene dunk regulates myosin at the basal array. I identified anillin (Scraps in Drosophila), a conserved scaffolding protein in cytokinesis, as the primary …

Evaluation Of Nutrient Digestibility Of Weaned Calves From Early And Late Shedding Dams, Jennifer Keele

Theses and Dissertations

Researchers have investigated several factors that could alter fetal growth, including nutrient restriction (Valiente et al., 2021), hair shedding (Gray et al., 2011), and extreme hot and cold temperatures (Davidson et al., 2022). Hot temperatures and increased humidity percentages in the southeast United States caused researchers to investigate the hair coats of Angus cattle in the commercial production setting. An improvement in fiber digestibility and calf birth and weaning weights has been observed in Angus dams that shed 50% of the winter hair coat by May (Gray et al., 2011; Burnett et al., 2021). Our objective of this experiment was …

Microglia Refine Early Multisensory Circuits In The Lateral Cortex Of The Inferior Colliculus In A Complement-Dependent Manner, Shaida Hamidi

Masters Theses, 2020-current

Microglia cells (MGCs), the resident macrophage of the brain, play a pivotal role in synaptic pruning of newly established circuits during early critical periods. Classical complement cascade signaling enables MGCs to identify unnecessary or underutilized contacts and specifically target them for removal and subsequent degradation. Such recognition and engulfment behaviors require receptor-ligand interactions, whereby “eat me” tags (complement component 3, C3) bind their cognate receptor (complement receptor 3, CR3) expressed on MGCs. Compromised complement signaling in certain systems results in under-pruning or unrefined map configurations, and is thought perhaps to underlie certain autism-related behavioral phenotypes (e.g. sensory hypersensitivities, decreased social …

Understanding The Regulatory Context And Mechanism Of Hlh-25 Mediated Transcriptional Repression, Dagmawi Mamo

Masters Theses, 2020-current

The HES family of transcription factors are primarily repressors of transcription that play critical roles in mammalian embryogenesis by regulating cell differentiation and proliferation. Proper functioning of HES proteins is crucial in humans, as mutations or misexpression of HES1 is associated with lung, pancreas, colon, and other cancers. HES1 may mediate short-range or long-range repression through DNA-binding and or protein-protein interactions with other factors. However, prior genetic studies have not fully elucidated how the context-specific binding of HES1, or its C. elegans ortholog HLH-25, promotes the repression of transcription. Characterization of the cis-regulatory context and mechanism of HLH-25 mediated repression …

Growth Plate Cartilage: Understanding The Contribution Of Adhesion To Column Formation And Matrix Structure, Sydney E. Greer

Theses & Dissertations

Throughout fetal and adolescent development, bone growth is regulated by fine-tuned and controlled maturation of chondrocytes through a cartilaginous template called the growth plate. Bone growth rate is controlled through cell enlargement and extracellular matrix deposition, while the polarized arrangement of proliferative chondrocytes into columns aligned with the long axis of the bone potentiate growth. Chondrocytes are surrounded by a complex three-dimensional arrangement of matrix molecules, all of which are secreted by chondrocytes and assembled/remodeled to support the biological functions of the cell. Adhesion receptors found on the cell membrane of chondrocytes are crucial to the organization of matrix proteins …

Measuring Energy Demands Of Dynamic Remodeling Events During Embryogenesis In Live Drosophila Embryos, Grayson Young

Biological Sciences Undergraduate Honors Theses

Embryonic development is a complex process requiring dynamic cell movements to create complex tissue structures. We assume that these embryonic dynamic remodeling events are highly energy intensive and that this energy expenditure is mediated by mitochondria. However, this has been difficult to demonstrate in live embryos. Convergent extension of the Drosophila neuroectoderm is a promising system to study the bioenergetics of tissue remodeling because it changes from a static to a dynamically remodeling tissue with temporal precision. We hypothesize that the switch from static to dynamic development at the onset of convergent extension will be accompanied by an increase in …

Mitochondrial Roles In Developmentally Programmed Heart Disease, Eli John Louwagie

Dissertations and Theses

Offspring of diabetic and obese mothers (ODOM) have greater risks of heart disease at birth and later in life. However, prevention is hindered because underlying mechanisms are poorly understood. Mounting studies in the Developmental Origins of Health and Disease field suggest that mitochondria play key roles in developmentally programmed heart disease similar to the roles they play in cardiomyopathy in adults with diabetes and obesity. However, whether mitochondria are responsible for the short[1]and long-term cardiac disease seen in ODOM remains unknown. Here, we sought to delineate the roles of mitochondria in the hearts of ODOM, determine whether mitochondria are playing …

Examining Transcriptional Regulators During Muscle Development In Drosophila Melanogaster, Chaamy Yapa

Student Theses and Dissertations

In Drosophila melanogaster embryos, a distinct approach to study the transcriptional regulation is to examine the larval somatic muscle development. Transcription factors are essential regulatory proteins that help to control gene expression and respond to signaling pathways and various cues. Today, there are at least twenty transcription factors that have been discovered to contribute to the development of the 30 distinct larval somatic muscles in each abdominal hemisegment of Drosophila melanogaster. Several studies have already been conducted on muscle regulatory transcription factors including midline and apterous. These transcription factors were shown to control the development of muscles through mutant …

The Effects Of Glycolytic Mutations In Drosophila Melanogaster Muscle Development, Coco Lim

Student Theses and Dissertations

Muscle atrophy, or muscle wasting, is caused due to lack of physical activity for an extended period of time, due to muscle diseases (such as muscle dystrophies), cancer chemotherapies, and aging. It is also extensively found on astronauts after spaceflight, particularly missions of long durations. Muscle cells are dependent on different metabolic pathways to optimize Adenosine triphosphate (ATP) production to compensate for muscle exertion. Glycolysis converts glucose into ATP producing pyruvate, which can be sent into the citric acid cycle or converted to lactate (lactic acid). Muscles preferentially use lactate production, despite the fact that fewer molecules of ATP are …

Transcriptional Regulation Of Stem Cell Function In The Drosophila Central Nervous System, Amalia S. Parra

Biology ETDs

Development of multicellular organisms depends on coordination of various molecular mechanisms to ensure proper tissue size and structure. This is accomplished through intrinsic and extrinsic cues that regulate cell growth and proliferation both spatially and temporally. These well-coordinated signals are present from early developmental stages and remain active throughout development to ensure tissue structure is appropriate for function. This is particularly important in early cell types that form specialized lineages such as stem cells or those found throughout the body such as epithelia. While much progress has been made in understanding growth regulatory mechanisms, several fundamental aspects remain unknown. This …

Investigation The Plugging Behavior Of Virus Filters, Iman Abdulqader Saab

Graduate Theses and Dissertations

A virus filtration step is integral to the manufacturing of biopharmaceuticals to ensure viral safety. A virus filter is a single-use device that uses a size-based separation process and has a unique structure with minimal defects, so that contaminating virus particles cannot pass through the membrane pores, while therapeutic molecules can. The development of novel antibodies (Abs), including significant increases in product titers, is frequently challenged by virus filter fouling, making a better understanding of the underlying mechanisms essential. This thesis focused investigating of the effect of prefilter types, buffer type and salt content on virus filtration performance. The impact …

Functional Analysis Of Daxx In Tumorigenesis Of Pancreatic Neuroendocrine Tumors And Embryonic Development, Chang Sun

Dissertations and Theses (Open Access)

Death domain-associated protein 6 (Daxx) is a histone chaperone specific to Histone 3.3 (H3.3). DAXX interacts with ATRX forming a chromatin remodeling complex, which deposits H3.3 into telomeric and pericentric region of the genome. The importance of Daxx was manifested in embryonic development. The loss of Daxx leads to early lethality in mouse embryos around E6.5. Moreover, sequencing studies have revealed the importance of DAXX in human tumors. Mutually exclusive mutations in DAXX and ATRX occur in about 30% of pancreatic neuroendocrine tumors (PanNETs). Although lots of progress has been made in studying functions of DAXX, we still do not …

Adipocytes And Innate Immunity In Systemic Sclerosis, Nancy Wareing

Dissertations and Theses (Open Access)

Systemic sclerosis (SSc; scleroderma) is a chronic systemic autoimmune and connective tissue disorder characterized by vasculopathy, autoimmune phenomena, and widespread fibrosis. Skin thickening and tightening is the cardinal feature of SSc and is responsible, in part, for the considerable morbidity of this disease. There are currently no targeted treatments for skin manifestations in SSc, primarily due to our fragmented understanding of its pathophysiologic mechanisms. In PART I, we report a previously unappreciated link between aberrant expression of the developmental gene sine oculis homeobox homolog 1 (SIX1) in skin-associated adipocytes in SSc skin and the early loss of dermal white adipose …

Genetic Regulation Of Müllerian Duct Regression, Malcolm Moses

Dissertations and Theses (Open Access)

Mammals, including humans, develop progenitor tissues for both male and female reproductive tract organs before they fully differentiate into a male or female tract. The progenitor tissue for the male reproductive tract is known as the Wolffian duct (WD), and the progenitor tissue for the female reproductive tract is the Müllerian duct (MD). The WD further differentiates into the vas deferens, epididymis, and seminal vesicle, while the MD differentiates into the oviduct, uterus and upper vagina. An essential step in sex differentiation for males is the regression of the MD. This regression initiates with anti-Müllerian hormone (Amh) transcription …

Gonads Without Glp-1: Silencing Glp-1 In The Male Somatic Gonad In Caenorhabditis Elegans, Matthew Titus

Undergraduate Theses

In C. elegans, the gene glp-1 encodes for a Notch receptor called GLP-1, one of two found in C. elegans’ genome. The gene has been previously implicated in the development of the hermaphroditic germline as well as playing a role in the mitosis/meiosis decision. Genetic screening has further identified it as potentially playing a role in the development of the male somatic gonad, making it an ideal candidate for a reverse genetic. We did this by silencing glp-1 and observing if any alterations to the gonad’s phenotype occur.

Normally this could be done by performing a gene knockout. …

Understanding The Expression And Role Of Pros-1 In The Male Gonad Of C. Elegans, Jack Bozik

Undergraduate Theses

The gene pros-1 is a transcription factor that is highly expressed within neuronal sheath cells, glial cells, and excretory canal cells. pros-1 plays a role in cell determination of those cell types in the nematode C. elegans, which promotes organismal development. But the degree to which pros-1 presence is important is still not fully understood, because there are many genes involved in development that when mutated or damaged can result in unexpected phenotypes or even total loss of function to a certain developmental mechanism. What makes pros-1 valuable to research is that it is a functional homologue to a …

Does Oxybenzone Affect The Development Of Sea Urchins Up To The Gastrula Stage, And What Do We Do About It?, Claire Crozier

Honors Projects

Understanding the effects of anthropogenic factors, such as oxybenzone, on sea urchins is extremely important to protect the growth of coral reefs- the ocean’s hotspot for biodiversity. Spawning of sea urchins, Lytechinus variegatus, was induced and eggs were fertilized in different concentrations of oxybenzone contaminated water. 48 hours later, data was collected underneath a light microscope. Observations of the data indicate that oxybenzone negatively affects sea urchin development up until the gastrula stage. Using both my data and knowledge from standing literature, I decided to write a policy analysis paper to answer the question “what should we do regarding sunscreen …

Consciousness, Evolution, And The Self-Organizing Brain, Karen Seymour

Journal of Conscious Evolution

While evolution is guided by natural selection, it is internally driven by self-organizing processes. The brain encompasses these complementary forces and dynamics of evolution in both its structure and dynamics by embodying a historical record of the factors that have shaped it throughout its evolutionary past, as well as by being shaped by selective parameters in real time. Self-organization is evident in not only the brain’s structure and form, but also in the processes that support consciousness. From the convergence of complex structure and the novelty-generating dynamics of chaos that both characterize the brain arises the experience of explicit consciousness, …

Effects Of Withania Somnifera On Zebrafish, Diyari Bekhtyar

Student Works

Withania somnifera (commonly known as Ashwagandha), is a plant in which its root powder is sold as a dietary supplement. It is being commonly used as an anti-anxiety supplement to combat stress. While the sale of Withania somnifera is widely accessible and available throughout the U.S., it is concerning that a number of teens and young adults are taking this supplement without consulting a physician. Previous studies and claims conclude that Withania somnifera has both neuroprotective and antiinflammatory properties in human neuronal cells. We have chosen to test Withania somnifera’s effects on early embryonic development using Danio rerio, zebrafish, as …

Examining The Reproductive Ecology Of Terrapene Ornata In Western Nebraska, Katie Brighton, Keetan Munsell

2023 Midwest Ecology & Evolution Conference

Understanding the reproductive ecology of any species is vital for determining intraspecific variation in individual fitness, modeling population growth or persistence potential, and developing effective conservation strategies. The reproductive ecology of many species has been extensively studied (particularly in mammals); however, other taxonomic groups including many ectotherms has not been well documented. One such ectotherm is the ornate box turtle (Terrapene ornata), which, to our knowledge, has never had its reproductive ecology extensively examined, especially in the field. In this study, we examined the reproductive ecology of ornate box turtles over a six-week period in a mixed shortgrass prairie in …