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Articles 1 - 30 of 131

Full-Text Articles in Biology

The Impacts Of Embryo Development And Asynchronous Hatching On Morphology, Growth, And Development Of Larval Burbot (Lota Lota)., Andrew J. Shapiro Nov 2023

The Impacts Of Embryo Development And Asynchronous Hatching On Morphology, Growth, And Development Of Larval Burbot (Lota Lota)., Andrew J. Shapiro

All NMU Master's Theses

Burbot (Lota lota) are native fish in Lake Superior and typically spawn during the winter under the ice or by migrating up rivers. The early life history of larval burbot, where they dispurse, how fast they develop, and what their survival rates have not been extensively studied. Asynchronous hatching is a strategy used by other cod species as a bet-hedging strategy to ensure that some larvae are hatched in more advantageous conditions in a varying environment. Asynchronous hatching has been documented in burbot, but the extent of the period and the impacts that asynchrony has on the development of …

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Phenotypic Plasticity Of Male Calls In Two Populations Of The Katydid Neoconocephalus Triops (Insecta: Tettigoniidae), Oliver M. Beckers, Teiya Kijimoto, Johannes Schul Oct 2023

Phenotypic Plasticity Of Male Calls In Two Populations Of The Katydid Neoconocephalus Triops (Insecta: Tettigoniidae), Oliver M. Beckers, Teiya Kijimoto, Johannes Schul

Faculty & Staff Research and Creative Activity

The ability to respond to environmental changes plays a crucial role for coping with environmental stressors related to climate change. Substantial changes in environmental conditions can overcome developmental homeostasis, exposing cryptic genetic variation. The katydid Neoconocephalus triops is a tropical species that extended its range to the more seasonal environment of North America where it has two reproductive generations per year. The harsher winter conditions required adults to diapause which resulted in substantially different mating calls of the diapausing winter animals compared to the non-overwintering summer animals in northern Florida. The summer call corresponds to that of tropical populations, whereas …

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Understanding The Environmental And Genetic Influence On Fluctuating Asymmetry And Developmental Instability In Primates, Ashly N. Romero Aug 2023

Understanding The Environmental And Genetic Influence On Fluctuating Asymmetry And Developmental Instability In Primates, Ashly N. Romero

Graduate Theses and Dissertations

This dissertation explored the impact of environmental factors on the development and perpetuation of fluctuating asymmetry (FA) and sought to understand the role evolution may play in the FA exhibited in two primate populations: the free-ranging Cayo Santiago rhesus macaques (Macaca mulatta) and the Southwest National Primate Research Center olive baboons (Papio hamadryas anubis). Demographic, ontogenetic, secular, external, and genetic factors were examined. Specifically, this dissertation investigated FA over all ontogenetic stages, across decades, between sexes, in association with ecological catastrophes, and with tooth pathology to try and tease apart factors that may influence FA and developmental instability. This dissertation …

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Southern Sea Otter (Enhydra Lutris Nereis) Fur Morphology, Thermal Function, And Buoyancy Across Ontogeny, Kate Riordan Jun 2023

Southern Sea Otter (Enhydra Lutris Nereis) Fur Morphology, Thermal Function, And Buoyancy Across Ontogeny, Kate Riordan

Master's Theses

Sea otters (Enhydra lutris) have the densest fur of any animal, and the hairs function to trap a layer of air that is used for insulation. When a sea otter is born, it has a natal pelage (baby fur), and sea otters eventually molt that fur and replace it with a pelt resembling the adult fur. Sea otter fur is composed of 3 types of hairs: underhairs, intermediate hairs, and guard hairs. Sea otters are more susceptible to the negative effects of oiling from oil spills compared to other marine mammal species because they solely rely on fur …

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Notes On Lung Development In South African Ghost Frogs (Anura: Heleophrynidae), Jackson R. Phillips, Jens Reissig, Gary Kyle Nicolau Apr 2023

Notes On Lung Development In South African Ghost Frogs (Anura: Heleophrynidae), Jackson R. Phillips, Jens Reissig, Gary Kyle Nicolau

Biology Student Research

Lungs are a prototypical trait of most tetrapods, but some amphibians have become secondarily lungless over evolutionary time. Anuran (frog) tadpoles offer an opportunity to examine lung loss from an evolutionary perspective, because there are many independent instances where lungs are not inflated until adulthood, and so are functionally lost. Lung loss is typically associated with living in fast-flowing streams, and so we examined larval lung development in the stream specialist family Heleophrynidae. We find that one genus, Hadromophryne Van Dijk, 2008, has large lungs as tadpole, while the other genus, Heleophryne Sclater, 1898, has much smaller, stunted lung buds. …

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The Impact Of Polychlorinated Biphenyls On The Development Of Zebrafish (Danio Rerio), Megan Moma Jan 2023

The Impact Of Polychlorinated Biphenyls On The Development Of Zebrafish (Danio Rerio), Megan Moma

WWU Graduate School Collection

Polychlorinated biphenyls (PCBs) are a group of 209 highly stable molecules that were used extensively in industry. Although their commercial use ceased in 1979, they are still present in many aquatic ecosystems due to improper disposal, oceanic currents, atmospheric deposition, and hydrophobic nature. PCBs pose a significant and ongoing threat to the development and sustainability of aquatic organisms. Our hypothesis is that PCB concentration will significantly affect development. Zebrafish (Danio rerio) were exposed to a standard PCB mixture (Aroclor 1254) for the first 5 days post fertilization, as there is a gap in knowledge during this important developmental …

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Spatiotemporal Characterization Of The Prr12 Paralogues In Zebrafish, Renee Jeannine Resendes Feb 2022

Spatiotemporal Characterization Of The Prr12 Paralogues In Zebrafish, Renee Jeannine Resendes

Electronic Thesis and Dissertation Repository

Pathogenic variants in the human PRR12 (Proline Rich 12) gene are associated with PRR12-related Neuroocular Syndrome. However, little is known about the gene/protein function. The zebrafish was utilized to address this, as its attributes place it as a premier model to study genes involved in human development and disease. In situ hybridization and RT-PCR of embryos and larvae, and qRT-PCR of adult tissues revealed the spatial and temporal distributions of the prr12 paralogues: prr12a and prr12b. Both paralogues were detected from the maternal and zygotic transcriptomes in a global and diffuse expression pattern, and there was enrichment …

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Understanding The Effects Of Embryonic Hyperglycemia On Retinal Development And Maintenance, Kayla Titialii-Torres Jan 2022

Understanding The Effects Of Embryonic Hyperglycemia On Retinal Development And Maintenance, Kayla Titialii-Torres

Theses and Dissertations--Biology

Hundreds of millions of people are affected by diabetes worldwide. Whether they are diagnosed with prediabetes or Type I or II diabetes, there are a variety of mechanisms in the pathogenesis of diabetes. Diabetes is a disease which consists of recurring states of hyperglycemia that can be difficult to manage due to either lack of insulin production or improper utilization of insulin. While these mechanisms of action differ, complications induced by diabetes occur in both poorly regulated Type I and II. Common complications of diabetes include nerve damage, kidney damage, and eye damage. Eye damage specifically is called diabetic retinopathy …

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Linking Ecomechanical Models And Functional Traits To Understand Phenotypic Diversity, T. E. Higham, L. A. Ferry, L. Schmitz, D. J. Irschick, S. Starko, P. S L Anderson, P. J. Bergmann, H. A. Jamniczky, L. R. Monteiro, D. Navon, J. Messier, E. Carrington, S. C. Farina, K. L. Feilich, L. P. Hernandez, Michele A. Johnson, S. M. Kawano, C. J. Law, S. J. Longo, C. H. Martin, P. T. Martone, A. Rico-Guevara, S. E. Santana, K. J. Niklas Sep 2021

Linking Ecomechanical Models And Functional Traits To Understand Phenotypic Diversity, T. E. Higham, L. A. Ferry, L. Schmitz, D. J. Irschick, S. Starko, P. S L Anderson, P. J. Bergmann, H. A. Jamniczky, L. R. Monteiro, D. Navon, J. Messier, E. Carrington, S. C. Farina, K. L. Feilich, L. P. Hernandez, Michele A. Johnson, S. M. Kawano, C. J. Law, S. J. Longo, C. H. Martin, P. T. Martone, A. Rico-Guevara, S. E. Santana, K. J. Niklas

Biology Faculty Research

Physical principles and laws determine the set of possible organismal phenotypes. Constraints arising from development, the environment, and evolutionary history then yield workable, integrated phenotypes. We propose a theoretical and practical framework that considers the role of changing environments. This 'ecomechanical approach' integrates functional organismal traits with the ecological variables. This approach informs our ability to predict species shifts in survival and distribution and provides critical insights into phenotypic diversity. We outline how to use the ecomechanical paradigm using drag-induced bending in trees as an example. Our approach can be incorporated into existing research and help build interdisciplinary bridges. Finally, …

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Evolution And Development Of Staminodes In Paronychia (Caryophyllaceae), Andrea D. Appleton Mar 2021

Evolution And Development Of Staminodes In Paronychia (Caryophyllaceae), Andrea D. Appleton

Honors College Theses

Staminodes are infertile stamens that have evolved numerous times in flowering plants and exhibit a vast array of forms and functions. Variation in staminodes suggests that numerous evolutionary processes underlie their origins, but to understand their how and why they evolved, comparative studies are needed in groups of closely related species. Identifying structures as staminodes is not always straightforward and sometimes requires corroborating phylogenetic and developmental evidence. Staminodial structures in Paronychia (Caryophyllaceae), for example, vary in shape and size and have been referred to as both petals and staminodes, rendering their homology uncertain. The development of staminodes was compared across …

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Mitochondrial Oma1 And Opa1 As Gatekeepers Of Organellar Structure/Function And Cellular Stress Response, Robert Gilkerson, Patrick De La Torre, Shaynah St. Vallier Mar 2021

Mitochondrial Oma1 And Opa1 As Gatekeepers Of Organellar Structure/Function And Cellular Stress Response, Robert Gilkerson, Patrick De La Torre, Shaynah St. Vallier

Biology Faculty Publications and Presentations

Mammalian mitochondria are emerging as a critical stress-responsive contributor to cellular life/death and developmental outcomes. Maintained as an organellar network distributed throughout the cell, mitochondria respond to cellular stimuli and stresses through highly sensitive structural dynamics, particularly in energetically demanding cell settings such as cardiac and muscle tissues. Fusion allows individual mitochondria to form an interconnected reticular network, while fission divides the network into a collection of vesicular organelles. Crucially, optic atrophy-1 (OPA1) directly links mitochondrial structure and bioenergetic function: when the transmembrane potential across the inner membrane (ΔΨm) is intact, long L-OPA1 isoforms carry out fusion of the mitochondrial …

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The Influence Of Autism Linked Gene Topoisomerase 3b (Top3b) On Neural Development In Zebrafish, Sydney Doolittle Mar 2021

The Influence Of Autism Linked Gene Topoisomerase 3b (Top3b) On Neural Development In Zebrafish, Sydney Doolittle

Honors College Theses

Autism Spectrum Disorder is a class of developmental disabilities characterized by a spectrum of social, communication, and behavioral impairments in affected individuals. Studies have shown these defects stem from abnormal brain development during critical periods during early development. The underlying genetic cause of these impairments is not well understood but is believed to be a combination of a complex pairing of genetic and environmental factors. One of the genetic factors that has been recognized to influence the phenotypic symptoms of ASD is the enzyme topoisomerase 3β (top3β.) Topoisomerases are responsible for the prevention of supercoiling during DNA replication. Top3β is …

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Shorebird Response To Human-Induced Changes At Three Pinellas County Beaches, Rebecca J. Ruthberg-Campagna Mar 2021

Shorebird Response To Human-Induced Changes At Three Pinellas County Beaches, Rebecca J. Ruthberg-Campagna

USF Tampa Graduate Theses and Dissertations

Worldwide, shorebird habitat is being destroyed and degraded by development and sea level rise. Shorebirds depend on availability of pristine, undisturbed coastal habitats for resting and feeding during migration as well as for reproduction. Migratory shorebirds using the East Atlantic Flyway visit the Gulf of Mexico Beaches of Pinellas County, Florida as a stopover site during Fall and Spring migration. In addition to hosting migratory species, Pinellas County beaches are home to several year-round resident species that breed during Summer. Pinellas County is the most densely populated county in Florida, and its Gulf Coast is heavily developed with commercial and …

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The First Gynandromorph Of The Neotropical Bee Megalopta Amoena (Spinola, 1853) (Halictidae) With Notes On Its Circadian Rhythm, Erin Krichilsky, Álvaro Vega-Hidalgo, Kate Hunter, Callum Kingwell, Chelsey Ritner, William Wcislo, Adam Smith Feb 2020

The First Gynandromorph Of The Neotropical Bee Megalopta Amoena (Spinola, 1853) (Halictidae) With Notes On Its Circadian Rhythm, Erin Krichilsky, Álvaro Vega-Hidalgo, Kate Hunter, Callum Kingwell, Chelsey Ritner, William Wcislo, Adam Smith

All PIRU Publications

Gynandromorphy is an anomaly that results in an organism phenotypically expressing both male and female characteristics. Here we describe the first gynandromorph of the bee species Megalopta amoena (Spinola, 1853) (Halictidae, Augochlorini) and the second record of this anomaly within the genus Megalopta. Additionally, we analyzed the bee’s circadian rhythm, which has never before been quantified for a gynandromorph. The gynandromorph showed a deviant activity pattern; it was intermediate between that of the male and female M. amoena. Our results imply that the brains of bilateral gynandromorphs may have mixed sex-specific signaling. Based on four days of recording, …

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Investigation Into The Roles Of Her9 And Capn5 During Retinal Development And Regeneration, Cagney Coomer Jan 2020

Investigation Into The Roles Of Her9 And Capn5 During Retinal Development And Regeneration, Cagney Coomer

Theses and Dissertations--Biology

The formation of a healthy and functioning eye requires coordinated interactions between numerous signaling pathways and gene regulatory networks within the developing neural retina. Tight regulation of gene expression is required for cell specification and differentiation in this multilayered, light sensitive tissue. The photoreceptors are the light detecting cells of the retina, capable of functioning in both intense sunlight and dim light at night. When pigment cells of the photoreceptor outer segment are activated by light, a complex chain of events called phototransduction leads to the electrical signal cascade that is transmitted through the retina and ultimately to the brain …

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Region-Specific Modifications Of Synaptic Proteins In Response To Early-Life Adversity In The Rat Brain, Jameel Nasser Hamdan Jan 2020

Region-Specific Modifications Of Synaptic Proteins In Response To Early-Life Adversity In The Rat Brain, Jameel Nasser Hamdan

Open Access Theses & Dissertations

Drug addiction is a serious condition affecting approximately 19.7 million people in the United States alone (SAMHSA 2018). Exposure to stress and other adverse conditions has been shown to impact drug-taking behavior and making individuals more vulnerable to addiction. In those already suffering from addiction, abstaining from drug use often gives way to relapse after a stressful event (Lu, Shepard et al. 2003; Shaham, Erb et al. 2000). The experience of adversity during early-life can cause long-lasting changes in the brain, affecting development, behavior, learning and memory, and critical thinking processes, which may persist into adulthood (Aisa, Tordera et al. …

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Prenatal Aromatase Inhibition Alters Postnatal Immunity In Domestic Chickens (Gallus Gallus), Jeff W. Simkins, Abby E. Joseph, Frances Bonier, Z. Morgan Benowitz-Fredericks Jan 2020

Prenatal Aromatase Inhibition Alters Postnatal Immunity In Domestic Chickens (Gallus Gallus), Jeff W. Simkins, Abby E. Joseph, Frances Bonier, Z. Morgan Benowitz-Fredericks

Faculty Journal Articles

In birds, exposure to exogenous testosterone during embryonic development can suppress measures of immune function; however, it is unclear whether these effects are due to direct or indirect action via aromatization. Estradiol (E2) is synthesized from testosterone by the enzyme aromatase, and this conversion is a necessary step in many signaling pathways that are ostensibly testosterone-dependent. Many lines of evidence in mammals indicate that E2 can affect immune function. We tested the hypothesis that some of the immunomodulatory effects observed in response to in ovo testosterone exposure in birds are mediated by conversion to E2 by aromatase, by using fadrozole …

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Characterizing The Requirements For The Matricellular Protein, Dccn, In Nervous System Function, Elizabeth L. Catudio Garrett Jan 2020

Characterizing The Requirements For The Matricellular Protein, Dccn, In Nervous System Function, Elizabeth L. Catudio Garrett

Graduate Student Theses, Dissertations, & Professional Papers

The brain is organized as a complex network of specialized neurons that communicate via a combination of electrical and chemical signals. Our brains function to generate movement, control organ function, or direct complex behaviors; all of which requires the ability to regulate the flow of communication between circuits and networks. Work in this thesis addresses two areas of neuron communication: first, how does the release of more than one neurotransmitter from a single neuron impact behavior, and second, are matricellular proteins (MCPs) key contributors to synaptic transmission and neuron function? The conserved CCN family of MCPs have a …

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Investigating The Effects Of Climate Co-Stressors On Surf Smelt Energy Demands, Megan Russell Jan 2020

Investigating The Effects Of Climate Co-Stressors On Surf Smelt Energy Demands, Megan Russell

WWU Graduate School Collection

Surf smelt (Hypomesus pretiosus) are ecologically and economically important to the Pacific Northwest. They play a critical role in the food web and support numerous commercially important species and are an economically important baitfish. Surf smelt interact closely with the nearshore environment, utilizing approximately 10% of Puget Sound coastlines for spawning throughout the year. Surf smelt spawn at high tide and adhere fertilized eggs to beach sediment, causing their embryos to be exposed to air and seawater throughout embryonic development. Because of this unique life history, surf smelt may be susceptible to anthropogenic stressors including coastal development and …

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The 14-3-3 (Ywha) Proteins In Signalling And Development Of The Fruit Fly, Drosophila Melanogaster, Santanu De Dec 2019

The 14-3-3 (Ywha) Proteins In Signalling And Development Of The Fruit Fly, Drosophila Melanogaster, Santanu De

Biology Faculty Articles

The 14-3-3 (YWHA or Tyrosine 3-Monooxygenase/Tryptophan 5-Monooxygenase Activation proteins) are a family of highly conserved, homologous proteins critical to diverse cellular events including cell cycle, signal transduction and embryonic development. Various species-specific isoforms of 14-3-3 exist, encoded by separate genes. They are expressed in a wide variety of organisms ranging from plants to animals, including the fruit fly or Drosophila melanogaster. Drosophila is one of the most universally accepted model systems to study complex cellular mechanisms of signalling and development. However, regulation of these processes in fruit flies by the 14-3-3 proteins have not been entirely understood. This mini …

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Modification Of Host Behavior And Transmission In The Acanthocephalan Acanthocephalus Dirus: Effects Of Development, Intraspecific Conflict, And Host Sex, Sara R. Teemer Jun 2019

Modification Of Host Behavior And Transmission In The Acanthocephalan Acanthocephalus Dirus: Effects Of Development, Intraspecific Conflict, And Host Sex, Sara R. Teemer

College of Science and Health Theses and Dissertations

Parasites are organisms that live on or in another in order to survive. In some cases, parasites require more than one host to complete their life cycle and rely on a predation event for transmission to the next host. Inside the host, the parasite must access host resources to grow and develop from the non-infective to infective stages. At the infective stage, the parasite is able to survive within the definitive host. Development to this stage has been correlated with changes in antipredatory behaviors, body size and color, and reproduction of intermediate hosts in ways that may increase predation by …

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Metabolism Underlies Physiological Homeostasis In Drosophila, Omera B. Matoo, Cole R. Julick, Kristi Montooth Jun 2019

Metabolism Underlies Physiological Homeostasis In Drosophila, Omera B. Matoo, Cole R. Julick, Kristi Montooth

School of Biological Sciences: Faculty Publications

Organismal physiology emerges from metabolic pathways and subcellular structures like the mitochondria that can vary across development and among individuals. Here, we tested whether genetic variation at one level of physiology can be buffered at higher levels of biological organization during development by the inherent capacity for homeostasis in physiological systems. We found that the fundamental scaling relationship between mass and metabolic rate, as well as the oxidative capacity per mitochondria, changed significantly across development in the fruit fly Drosophila. However, mitochondrial respiration rate was maintained at similar levels across development. Furthermore, larvae clustered into two types—those that switched to …

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Play Behavior And The Development Of Boldness And Caution In Juvenile Belding’S Ground Squirrels (Urocitellus Beldingi), Madelene Shehan May 2019

Play Behavior And The Development Of Boldness And Caution In Juvenile Belding’S Ground Squirrels (Urocitellus Beldingi), Madelene Shehan

Master's Theses

The ubiquity of play among juvenile mammals suggests it provides adaptive benefits, potentially through influences on the development of temperament in young animals. Juvenile Belding’s ground squirrels (Urocitellus beldingi) must balance competing demands for boldness and caution imposed by the fundamental trade-off between their short active season and their vulnerability to predation. In this study, I evaluated whether play helps to facilitate the development of an appropriate balance between boldness and caution in juvenile U. beldingi.I observed the play behavior of juvenile U. beldingiand conducted flight-initiation distance tests to measure boldness-caution at the beginning and toward …

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Effects Of Herbicides On Zebrafish Embryo Development And Viability, Kayla Ray King May 2019

Effects Of Herbicides On Zebrafish Embryo Development And Viability, Kayla Ray King

MSU Graduate Theses

Environmental contaminants are chemicals of anthropogenic origin that are found in water, soil, and air, and are harmful to a wide variety of organisms (ORD US EPA, 2018-a). One common group of contaminants are herbicides. Though herbicides are used to control unwanted vegetation in agriculture, aquatic organisms and humans may be exposed to these herbicides through run off into streams and rivers, by drinking contaminated water, by consuming treated crops, by direct exposure, or through bioaccumulation. Thus the effect of these herbicides on animals needs further investigation. In this study, I sought to determine whether six different herbicides, which have …

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Fate Map Of The Blastoderm To Determine Segmental Fate In Tribolium Castaneum, Latanya Coke May 2019

Fate Map Of The Blastoderm To Determine Segmental Fate In Tribolium Castaneum, Latanya Coke

Senior Theses and Projects

Segmentation in arthropods has been modeled on the well-defined segmentation patterns found in Drosophila. In Drosophila, segments form simultaneously in the blastoderm where morphogenic gradients spanning the AP axis provide patterning inputs. However, in most arthropods, segments form sequentially from a posterior growth zone. Sequential segmentation in arthropods has recently been demonstrated to use a vertebrate- like segmentation clock (Sarrazin et al. 2012). The vertebrate segmentation clock is a molecular oscillator that regulates periodic somite formation (Gibb 2010). In the red flour beetle, Tribolium castaneum, the segmentation clock is coordinated by traveling waves of expression generated by a pair-rule gene …

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Synmuv B Proteins Regulate Chromatin Compaction During Development, Meghan Elizabeth Costello Apr 2019

Synmuv B Proteins Regulate Chromatin Compaction During Development, Meghan Elizabeth Costello

Dissertations (1934 -)

Tissue-specific establishment of repressive chromatin through creation of compact chromatin domains during development is necessary to ensure proper gene expression and cell fate. C. elegans synMuv B proteins are important for the soma/germline fate decision and mutants demonstrate ectopic germline gene expression in somatic tissue, especially at high temperature. To study chromatin compaction during development we visualized chromatin using both nuclear-spot assays and FISH of native synMuv B regulated loci. We showed that C. elegans synMuv B proteins regulate developmental chromatin compaction and that timing of chromatin compaction was temperature sensitive in both wild-type and synMuv B mutants. Chromatin compaction …

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Partial Characterization Of Putative Cyp86a Genes From Soybean, Trish Tully Mar 2019

Partial Characterization Of Putative Cyp86a Genes From Soybean, Trish Tully

Electronic Thesis and Dissertation Repository

Soybean (Glycine max [L.] Merr.) is a globally cultivated crop that is important to the sustainability of many industries. However, like all plants, optimal cultivation of soybean is threatened by detrimental environmental factors. For example, high yield of soybean is threatened by soil-borne pathogens like Phytophthora sojae. Resistance against P. sojae was previously positively correlated with aliphatic suberin deposition in soybean. As such, a deeper understanding of the biosynthesis of suberin may assist in engineering a resistant form of soybean, based on enhanced suberin content. In soybean, the ω-OH fatty acid monomers are predominant and most strongly correlated …

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Examining The Effects Of Fadrozole, An Aromatase Inhibitor, On Testosterone And Estrogen Production Of Domestic Chicken Embryos (Gallus Gallus), Abby E. Joseph Jan 2019

Examining The Effects Of Fadrozole, An Aromatase Inhibitor, On Testosterone And Estrogen Production Of Domestic Chicken Embryos (Gallus Gallus), Abby E. Joseph

Honors Theses

The hypothalamic-pituitary-gonadal (HPG) axis is responsible for the production of the hormones testosterone and estradiol, and testosterone is thought to contribute to regulation of the axis through a negative feedback mechanism. Regulation by negative feedback involves the product of a pathway turning off that pathway when enough product is made. However, because the enzyme P450 aromatase converts testosterone to estradiol, estradiol may also contribute to regulation of the HPG axis and other phenomena that have been attributed to testosterone, like the inhibition of immune function. Previous studies have injected birds with an aromatase inhibitor (presumably reducing estradiol production) and shown …

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A Trio Of Sigma Factors Control Hormogonium Development In Nostoc Punctiforme, Alfonso Gonzalez Jr. Jan 2019

A Trio Of Sigma Factors Control Hormogonium Development In Nostoc Punctiforme, Alfonso Gonzalez Jr.

University of the Pacific Theses and Dissertations

Cyanobacteria are prokaryotes capable of oxygenic photosynthesis, and for many species, nitrogen fixation, giving cyanobacteria an important role in global carbon and nitrogen cycles. Furthermore, multicellular filamentous cyanobacteria are developmentally complex, capable of differentiation into different cell types, including cells capable of nitrogen fixation and cells for motility, making them an ideal platform for studying development, as well as for practical use in biotechnology. Understanding how developmental programmes are activated require an understanding of the role of alternative sigma factors, which are required for transcriptional activation in bacteria. In order to investigate the gene regulatory network and to determine the …

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Analysis Of Brevundimonas Subvibrioides Developmental Signaling Systems Reveals Unexpected Differences Between Phenotypes And C-Di-Gmp Levels, Lauryn Anne Sperling Jan 2019

Analysis Of Brevundimonas Subvibrioides Developmental Signaling Systems Reveals Unexpected Differences Between Phenotypes And C-Di-Gmp Levels, Lauryn Anne Sperling

Electronic Theses and Dissertations

The DivJ-DivK-PleC signaling system of Caulobacter crescentus is a signaling network that regulates polar development and the cell cycle. This system is conserved in closely related bacteria, including the sister genus Brevundimonas. Previous studies had shown unexpected phenotypic differences between the C. crescentus divK mutant and the analogous mutant of Brevundimonas subvibrioides, but further characterization was not performed. Here, phenotypic assays analyzing motility, adhesion, and pilus production (the latter characterized by a newly discovered bacteriophage) revealed that divJ and pleC mutants have mostly similar phenotypes as their C. crescentus homologs, but divK mutants maintain largely opposite phenotypes than …

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