Department of Biological Sciences

Anthropogenic impacts, including urbanization and development of the Greater Everglades ecosystem, have severely reduced and fragmented populations of Bletia purpurea. Differences across populations in Florida, such as habitat preferences, blooming periods, and self-fertilization abilities have been documented. Genetic data is becoming essential for developing effective conservation strategies to prevent the disappearance of threatened orchids from the wild. Using a target capture method with the Orchidaceae963 baitset, we assessed the genetic diversity of eight wild populations and five cultivated sources of B. purpurea. Our findings reveal two areas of concern; S1 which forms a distinct genetic cluster, and E3, where inbreeding rates are notably high. Additionally, three of the five cultivated sources showed significant differentiation from the wild populations, highlighting the need for more diverse maternal lines in cultivation efforts. These results emphasize the critical role of genetic assessments in informing conservation strategies for threatened orchid populations.

Emerging research in mammals supports relationships between an animal’s health, including the stress response and cognition, and its gut microbiome. Most of what is known about this “microbiota-gut-brain-HPA axis” stems from captive mammalian research, while these relationships are largely untested in wild, non-mammalian populations. To test this in avian taxa, I conducted a series of studies with captive Zebra Finches (Taeniopygia guttata) and a wild population of Northern Cardinals (Cardinalis cardinalis). First, I quantified performance by Zebra Finches on cognitive tasks measuring learning and memory for comparison to alpha and beta diversity of the gut microbiome sampled via cloacal swab. Performance on cognitive tasks related to beta diversity but not alpha diversity, providing some of the first evidence of an avian microbiota-gut-brain axis. Next, testing for relationships between host fitness and the microbiome, I sought baseline relationships between free-living cardinals’ microbiomes and their sexual ornamentation, stress response, and body condition index. Bacterial diversity related to individual variation in body condition and several sexual ornaments, but not glucocorticoid concentrations. Finally, in an empirical test that an acute stress response can cause microbiome dysbiosis, I captured wild cardinals to sample their gut microbiome, stress response, body condition, and beak ornamentation, then recaptured and resampled individuals after ~11 days. Between captures, I administered one of two challenges to each cardinal: a temporary hold of an additional hour in a cage post-capture, repeated simulated territorial intrusions (STIs), or no challenge (as a control). Challenge type had no effect on change in alpha diversity between sample timepoints, but it had a significant impact on microbiome dissimilarity assessed by beta diversity between timepoints. Overall, the birds that showed the largest beta diversity and greatest decrease in alpha diversity between samples experienced the greatest increase in CORT scope; there were mixed results supporting a link between a reduction in beak ornamentation and microbiome dysbiosis. This is some of the first evidence of a proximate effect of a fitness challenge on the microbiome of an adult free-living songbird, with concurrent data on shifts in glucocorticoids, body condition, and ornamentation.

The goal of these studies was to quantify mechanical properties of elasmobranch (sharks and batoids) skin to understand the functional relationships between mechanics and morphology, and how these correspond to differences in swimming and ecology. I relate mechanical behaviors with morphological structures to elucidate the underlying contributions of the skin toward elasmobranch skin mechanics. I mechanically tested skin in uniaxial tension to failure to assess the tensile strain at maximum load (extensibility), ultimate tensile strength, Young’s Modulus of elasticity (stiffness), and toughness among diverse groups of elasmobranchs. Across three chapters, I compare mechanical behaviors of the skin among species of sharks and batoids (separately) among body regions, and between sexes and axes of stress (longitudinal and hoop). Among 20 shark species, I quantified mechanical properties among ecomorphotypes and ontogenetically (across three maturity stages) and found that mechanical behaviors increase ontogenetically and are governed by two different underlying trends (maturity and ecomorphology). I found that shark skin oriented in the hoop direction was stronger and stiffer compared to skin oriented longitudinally, as hoop-oriented skin maintains internal volume and hydrostatic pressure by resisting deformation. Shark skin oriented longitudinally was more extensible, allowing for increased stretchability anteroposterior as a shark’s body undulates along the longitudinal axis. Dermal denticles (placoid scales), tooth-like structures of enameloid and dentine, are rooted in the stratum compactum layer of the dermis, embedded in a collagen fiber network.

Cryptic species remain poorly studied in octopuses. Following the reinstatement of the cryptic species, Octopus americanus, suggestions that it should supplant two taxa, Octopus vulgaris types I & II, in the western central and southwestern Atlantic Ocean, respectively, had yet been investigated in southeast Florida. To delineate this species, an integrative approach including morphological assessments and phylogenetic analyses of mitochondrial (16S & COI) and nuclear (rhodopsin) genes was employed. The utility of swabbing as a minimally invasive alternative DNA sampling method to tissue was also investigated. This taxon displays similar morphological traits to O. americanus. Maximum Likelihood phylogenetic inference placed this taxon in a highly supported monophyletic group with O. americanus. Both sampling methods delineated this taxon, though tissue was more successful. These results indicate that southeast Florida’s O. vulgaris-like species represents O. americanus. Thorough species delineation approaches advance our understanding of biodiversity, evolution, and ecology, and inform management practices.

After an unexpected displacement of Atlantic spotted dolphins (Stenella frontalis) from Little Bahama Bank (LBB) to Great Bahama Bank (GBB) in 2013, the LBB immigrant and GBB resident spotted dolphins were observed socially merging and initiating courtship despite previous segregation on GBB post-displacement. This project assessed the genetic integration between them. Through microsatellite analyses and genetic differentiation, reciprocal gene flow appears to be occurring between the two communities. One male was confidently assigned paternity and six males were selected as the most likely candidate males of calves. Three mottled males were designated as the most likely candidate males of calves, indicating that younger males may be reproductively successful.

Microbial partners provide beneficial and detrimental functions to their hosts and other microbes through the exchange of metabolites and info chemicals. Developing an understanding of these micro-interactions has considerable implications for human health, agriculture, and ecosystem protection. Here, the microbial interactions of two important marine organisms: the Forcepia sp. sponge, a source of the potential anticancer compound, lasonolide A (LSA), and Pyrodinium bahamense, a dinoflagellate which produces the potent neurotoxin, saxitoxin, were investigated. Chapter 1 introduces marine microbial interactions, their importance in the function of organisms and ecosystems, and their applications in human health, agriculture and ecosystem production. Chapter 2 describes the identification and capture of the lasonolide biosynthetic pathway from a metagenomic fosmid library. This chapter also describes the assembly of the pathway into an expression vector and attempts to sustainably produce LSA through heterologous expression. Chapter 3 describes the identification and characterization of the bacterial associates of Pyrodinium bahamense, a toxin producing dinoflagellate found in the northern Indian River Lagoon. This chapter also describes potential chemical and molecular interactions occurring between P. bahamense and its associated cultivable bacteria. Chapter 4 describes the investigation into the effects microbial associates have on the physiology of P. bahamense. The completion of this work further describes microbial interactions occurring in marine environments, their influences and functions in the physiology and evolution of marine organisms, and the tools available for their investigation and utilization for human and ecosystem benefit.

Cancer is a leading cause of death in the U.S and across the world, with estimates indicating 17 million new cancer cases in 2018, 9.5 million of which resulted in death. Statistics show that in the past 20 years cancer death rates have decreased 27% due to emerging therapies. The use of chemotherapies to kill fast-growing cells in the body has become one of the most common cancer treatments in the world today. Chemotherapy-Induced Peripheral Neuropathies (CIPNs) are the most common side effects caused by chemotherapeutic agents. CIPNs have a prevalence of up to 85% in cancer patients undergoing chemotherapy. CIPNs triggered by chemotherapeutic drug use severely damage nerves branching from either the brain or spinal cord, initiating the development of acute and/or chronic symptoms. Platinum-based and taxane-based chemotherapeutics are among the most potent and versatile drugs available for combating cancer. The two of these drugs, carboplatin and docetaxel, are known to cause peripheral neuropathies and central neurotoxicity and were the focus of this project.

Endometriosis is a chronic disease that causes endometrial tissues to migrate and grow outside the uterus and is often associated with pain and infertility. The growths are estrogen-dependent but progesterone-resistant due to the lack of progesterone receptors. In the U.S., estrogen deprivation is the primary approach to treating the disease, which often leads to severe consequences such as osteoporosis and menopausal symptoms. KBU2046 is a chemical analog of genistein that has been shown to effectively inhibit the motility of prostate cancer cells with no toxicity to normal cells or estrogenic activity (Li Xu et al., 2010). This in vitro study showed that KBU2046 at 10μM significantly decreased the viability of 12Z cells to 27% and 34% at 24 hours and 48 hours posttreatment, respectively. At 48 hours post-treatment, micromolar concentrations of the combinations of KBU2046 with dienogest or calcitriol effectively decreased the viability of 12Z cells to 16% and 58.9%, respectively. KBU2046 with sodium butyrate decreased viability to 7.7%, but millimolar concentrations of the latter were required. KBU2046, in combination with calcitriol, synergistically decreased the migration and colony formation of the 12Z cells to 19.3% and 45.7%, respectively. KBU2046 and Calcitriol-treated 12Z cells are slower to the recovery of growth following treatment. KBU2046 and calcitriol decreased the secretion of PGE2 to 6.5% and 16.7%, respectively, while ethanol and the combinations of ethanol and DMSO increased the secretion of PGE2 to 83.8%, and 63.2%, respectively. In conclusion, a combination of KBU2046 and calcitriol at micromolar concentrations markedly inhibited the migration and growth of endometrial cells while decreasing the secretion of a key inflammatory molecule. In vivo studies with mouse models are needed to evaluate using a combination of KBU2046 and calcitriol for endometriosis therapy and whether millimolar plasma concentrations can be safely achieved by dietary means.

Alzheimer's disease (AD) is projected to triple by 2050, highlighting the urgent need for disease-modifying treatment strategies. Our gene therapy approach tackles three critical challenges: a) delivering drugs effectively to the brain and brain bioavailability of those delivered drugs, b) intervening early in the disease process to prevent progression into nonreversible stages, and c) managing the behavioral and psychological symptoms of dementia (BPSD) that significantly impact patients and caregivers. Our non-invasive ocular delivery system effectively delivered therapies to CNS as indicated by the localization of those transcribed genes and translated protein products in different brain regions, including the hippocampus, cortex, dorsal lateral geniculate nucleus, red nucleus, and pontine nucleus This approach could overcome the limitations of traditional drug delivery methods for neurological diseases. In a 3xTg AD mouse model of AD, we evaluated the efficacy of Choline Acetyltransferase (ChAT) gene therapy on early disease progression. A single treatment improved impaired memory functions such as cognitive flexibility, memory extinction and working memory, reduced amyloid beta oligomers and phosphorylated tau protein levels, and enhanced mitochondrial dynamics through the regulation of fusion, fission and mitophagy. Additionally, ChAT gene therapy modulated apoptosis, inflammation and the activity of microglia and astrocytes in parts through the activation of AKT. These findings suggest ChAT gene therapy's potential to slow or prevent AD
progression if administered early in the disease course.

Endometriosis is an inflammatory metastatic disease that affects the endometrium of one in ten women. Endometrial tissue grows outside the uterus causing severe discomfort and pain. This disease is estrogen dependent, driving the invasion and migration of endometrial lesions to form the ectopic uterus. Due to the hormonal imbalance of increased estrogen, there is progesterone resistance leading to a decrease in progesterone receptors. This study determined if the combination of Melatonin, a naturally occurring hormone, and Calcitriol, the active form of vitamin D, had a synergistic or additive effect on the growth and migration of endometrial cells. The experiments utilized the immortalized endometriotic epithelial (12 Z) cell lines to conduct cell viability, wound closure, and clonogenic growth and growth curves. Results revealed that a combination of Melatonin and Calcitriol had an additive effect in reducing cell viability, inhibiting migration, and decreasing proliferation.