Hemolytic disorders are characterized by hemolysis and are prone to thrombosis. Previously, it has been shown that the RNA released from damaged blood cells activates clotting. However, the nature of RNA released from hemolysis is still elusive. We found that after hemolysis, the red blood cells from both zebrafish and humans release 5.8S rRNA. This RNA activated coagulation in zebrafish and human plasmas. Using both natural and synthetic 5.8S rRNA and its synthetic truncated fragments, we found that the 3'-end 26 nucleotide-long RNA (3'-26 RNA) and its stem-loop secondary structure were necessary and sufficient for clotting activity. Corn trypsin inhibitor (CTI), a coagulation factor XII (FXII) inhibitor blocked 3'-26 RNA-mediated coagulation activation of both zebrafish and human plasma. CTI also inhibited zebrafish coagulation in vivo. 5.8S rRNA monoclonal antibody inhibited both 5.8S rRNA- and 3'-26 RNA-mediated zebrafish coagulation activity. Both 5.8S rRNA and 3'-26 RNA activates normal human plasma but did not activate FXII-deficient human plasma. Taken together, these results suggested that the activation of zebrafish plasma is via FXII-like protein. Since zebrafish has no FXII and hepatocyte growth factor activator (Hgfac) has sequence similarities to FXII, we knocked down the hgfac in adult zebrafish. We found that plasma from …

Plant yield is an agronomic trait dependent on the transport of photosynthate from mature source leaves to sink tissues. Manipulating phloem transport may lead to increased yield, however in a previous study, Arabidopsis thaliana overexpressing sucrose transporter AtSUC2 in the phloem resulted in stunted growth and an apparent P-deficiency. In the course of further characterizing the phenotype and identifying the causative mutation, this research included 1) reverse genetics to test genes hypothesized to modulate carbon-phosphate interactions; 2) whole genome sequencing to identify all T-DNA insertions in plants displaying the phenotype; 3) genetic crosses and segregation analysis to isolate the causative mutation; and 4) transcriptomics to capture gene-expression profiles in plants displaying the phenotype. These phenotypes were traced to a T-DNA insertion located on chromosome 4. Transcriptomics by RNA-Seq and data analysis through bioinformatics pipelines suggest disruptions in metabolic and transport pathways that include phosphate, but do not support a direct role of well-established phosphate acquisition mechanisms. Gene At1G78690 is immediately downstream of the T-DNA insertion site and shows modestly increased expression relative to wild type plants. At1G78690 encodes O-acyl transferase, which is involved in processing N-acylphosphotidyl ethanolamine (NAPE) to N-acyl ethanolamine (NAE). Exogenous NAE application causes stunted growth in specific …

Synthetic biology is a rapidly growing field that aims to treat cellular biological networks in an analogous way to electrical circuits. However, the field of plant synthetic biology has not grown at the same pace as bacterial and yeast synthetic biology, leaving a dearth of characterized tools for the community. Due to the need for tools for the synthetic plant biologist, I have endeavored to create a library of well-characterized TATA box variants in the cauliflower mosaic virus (CaMV) 35S promoter using the standardized assembly method Golden Braid 2.0. I introduced single nucleotide changes in the TATA box of the CaMV 35S promoter, a genetic part widely used in plant gene expression studies and agricultural biotechnology. Using a dual-luciferase reporter system, I quantified the transcriptional strength of the altered TATA box sequences and compared to the wild-type sequence, both in transient protoplast assays and stable transgenic Arabidopsis thaliana plants. The library of TATA-box modified CaMV 35S promoters with varying transcriptional strengths created here can provide the plant synthetic biology community with a series of modular Golden Braid-adapted genetic parts that can be used dependably and reproducibly by researchers to fine-tune gene expression levels in complex, yet predictable, synthetic genetic circuits.

Reptiles can often experience perturbations that greatly influence their metabolic status (e.g., temperature, exercise, digestion, and ontogeny). The most common cause of fluctuations in metabolic status in post-embryonic reptiles is arguably digestion and physical activity (which will be further referred to as exercise). The objective of this thesis is to determine the mechanisms involved in CO2 transport during digestion, determine the mechanisms that allow for the maintenance of acid-base homeostasis during digestion, and observing the effect of an understudied form of exercise in semi-aquatic reptiles on the regulation of metabolic acidosis and base deficit. This dissertation provided evidence for potentially novel and under investigated mechanisms for acid-base homeostasis (e.g., small intestine and tissue buffering capacity; Chapters 3 & 4), while also debunking a proposed hypothesis for the function of an anatomical feature that still remains a mystery to comparative physiologist (Chapter 2). This thesis is far from systematic and exhaustive in its approach, however, the work accomplished in this dissertation has become the foundation for multiple distinct paths for ecologically relevant investigations of the regulation of metabolic acidosis/alkalosis in reptiles.

Peregrine falcon subspecies taxonomy is widely debated due to uncertainty in their evolutionary history and unresolved phylogenetic reconstruction using both morphological and molecular data. Previous genetic work has shown limited support for subspecies taxonomy largely as a result of molecular markers used, potential contemporary gene flow, incomplete lineage sorting, and ancestral polymorphisms. With the advent of next-generation sequencing, the cost of generating large amounts of sequence data has dropped significantly, making whole genome re-sequencing (WGR) studies of non-model organisms more tangible. In this study, WGR methods have been utilized to investigate the phylogenetic relationships among all 20 currently recognized peregrine falcon subspecies. By generating whole-genome data for all 20 subspecies, subspecies specific diagnostic SNPs have been identified to aid in subspecies delimitation. Results of this study broadly support current subspecies, however, reveal that further study is needed to investigate regional relationships among subspecies in Asia, Australia, and western North America. With these results, conservation efforts can be further supported by allowing for accurate delimitation of local subspecies and subspecies boundaries.

Alteration in diet and knockdown of detoxification genes impacts the response of C. elegans to oxygen deprivation stress. I hypothesized that feeding worms a vitamin D3-supplementation diet would result in differential oxygen deprivation stress response. We used a combination of wet lab and transcriptomics approach to investigate the effect of a vitamin-D3 supplemented diet on the global gene expression changes and the anoxia response phenotype of C. elegans (Chapter 2). C. elegans genome consists of 143 detoxification genes (cyp and ugt). The presence of a significant number of genes in these detoxification families was a challenge with identifying and selecting specific cyp and ugt genes for detailed analysis. Our goal was to understand the evolution, phylogenetic, and expression of the detoxification enzymes CYPs and UGTs in C. elegans (Chapter 3). We undertook a phylogenetic and bioinformatics approach to analyze the C. elegans, detoxification family. Phylogenetic analysis provided insight into the association of the human and C. elegans xenobiotic/endobiotic detoxification system. Protein coding genes in C. elegans have been predicted to be human orthologs. The results of this work demonstrate the role of C. elegans in the identification and characterization of vitamin D3 induced alterations in gene expression profile and anoxia …

There is increasing evidence indicating that exposure to air pollutants may be associated with the onset of several respiratory diseases such as allergic airway disease and chronic obstructive pulmonary disorder (COPD). Many lung diseases demonstrate an outgrowth of pathogenic bacteria belonging to the Proteobacteria phylum, and the incidence of occurrence of these diseases is higher in heavily polluted regions. Within the human body, the lungs are among the first to be exposed to the harmful effects of inhaled pollutants and microbes. Research in the past few decades have expounded on the air-pollution-induced local and systemic inflammatory responses, but the involvement of the lung microbial communities has not yet been well-characterized. Lungs were historically considered to be sterile, but recent advances have demonstrated that the lower respiratory tract is replete with a wide variety of microorganisms - both in health and disease. Recent studies show that these lung microbes may play a significant role in modulating the immune environment by inducing IgA and mucus production. Air pollutants have previously been shown to alter intestinal bacterial populations that increase susceptibility to inflammatory diseases; however, to date, the effects of traffic-generated air pollutants on the resident microbial communities on the lungs have not …

Recent epidemiological studies have demonstrated a correlation between the manifestation of non-alcoholic fatty liver disease (NAFLD) and ambient air pollution levels, which is exacerbated by the presence of other risk factors, such as diabetes, dyslipidemia, obesity, and hypertension. We investigated the hypothesis that exposure to a mixture of gasoline and diesel engine emissions (MVE) coupled with the concurrent consumption of a high-fat (HF) diet promotes the development of a NAFLD phenotype within the liver. Three-month-old male C57Bl/6 mice were placed on either a low fat or HF diet and exposed via whole-body inhalation to either filtered (FA) air or MVE (30 µg PM/m3 gasoline engine emissions + 70 µg PM/m3 diesel engine emissions) 6 hr/day for 30 days. Histology revealed mild microvesicular steatosis and hepatocyte hypertrophy in response to MVE exposure alone, compared to FA controls, yielding a classification of "borderline NASH" under the criteria of the modified NAFLD active score (NAS) system. As anticipated, animals on a HF diet exhibited moderate steatosis; however, we also observed inflammatory infiltrates, hepatocyte hypertrophy, and increased lipid accumulation, with the combined effect of HF diet and MVE exposure. Immunofluorescence staining and RT-qPCR of the liver revealed the presence of lipid peroxidation, altered expression …

With effective engineering using synthetic biology approaches, plant-based platforms could conceivably be designed to minimize the production costs and wastes of high-value products such as medicines, biofuels, and chemical feedstocks that would otherwise be uneconomical. Additionally, modern agricultural crops could be engineered to be more productive, resilient, or restorative in different or rapidly changing environments and climates. To achieve these complex goals, information-processing genetic devices and circuits containing multiple interacting parts that behave predictably must be developed. A genetic Boolean AND logic gate is a device that computes the presence or absence of two inputs (signals, stimuli) and produces an output (response) only if both inputs are present. Here, we optimized individual genetic components and used synthetic protein heterodimerizing domains to rationally assemble genetic AND logic gates that integrate two hormonal inputs in whole plants. These AND gates produce an output only in the presence of both abscisic acid and auxin, but not when either or neither hormone is present. Furthermore, we demonstrate the AND gate can also integrate two plant stresses, cold temperature and bacterial infection, to produce a specific response. The design principles used here are generalizable, and therefore multiple orthogonal AND gates could be assembled and rationally …

Flavonoids are polyphenolics compounds that constitute a major group of plant specialized metabolites, biosynthesized via the phenylpropanoid/polymalonate pathways. The resulting specialized metabolites can be due to decoration of flavonoid compounds with sugars, usually glucose, by the action of regiospecific UDP-glycosyltransferase (UGT) enzymes. In some cases, glycosylation can involve enzymatic attachment of other sugar moieties, such as glucuronic acid, galactose, rhamnose or arabinose. These modifications facilitate or impact the bioactivity, stability, solubility, bioavailability and taste of the resulting flavonoid metabolites. The present work shows the limitations of utilizing mammalian UDP-glucuronosyltransferases (UGATs) for flavonoid glucuronidation, and then proceeds to investigate plant UG(A)T candidates from the model legume Medicago truncatula for glucuronidating brain-targeted flavonoid metabolites that have shown potential in neurological protection. We identified and characterized several UG(A)T candidates from M. truncatula which efficiently glycosylate various flavonoids compounds with different/multiple regiospecificities. Biochemical characterization identified one enzyme, UGT84F9, that efficiently glucuronidates a range of flavonoid compounds in vitro. In addition, examination of the ugt84f9 gene knock-out mutation in M. truncatula indicates that UGT84F9 is the major UG(A)T enzyme that is necessary and sufficient for attaching glucuronic acid to flavonoid aglycones, particularly flavones, in this species. Finally, the identified UG(A)T candidates were analyzed via homology …

Microalgae being photosynthetic and having quick growth cycles can prove to be excellent candidates as biofactories for the production of aromatic compounds like para-hydroxybenzoic acid (pHBA) that act as a monomer in liquid crystal polymers. We developed transgenic lines of the model alga Chlamydomonas reinhardtii by performing nuclear transformation using electroporation. The transgenic cell lines expressed the ubiC gene that utilized chorismate from the shikimate pathway as a substrate to produce pHBA. The maximum yield of pHBA measured in these lines was 80 mg/L. Accruing pHBA can be toxic to the cells and the mechanism by which C. reinhardtii could detoxify pHBA is not known. C. reinhardtii genome was thus scanned for sequences similar to UDP-glucosyltransferase (UGT) that can transfer the glucose moiety to pHBA, rendering it non-toxic to the cell lines. Our analysis suggested the absence of any potential UGTs that could glycosylate pHBA and detoxify it. We further performed feeding experiments to test the ability of wt-type C. reinhardtii cells to detoxify pHBA and understand its fate. C. reinhardtii cells were fed with varying concentrations of pHBA and harvested at different time intervals. The HPLC chromatograms indicated a majority of the pHBA was catabolized. Based on these results, …

Box turtle (Terrapene carolina) populations are steadily declining due their unique natural history, effects of climate change, and anthropogenic land use change. There is a need for updated information on box turtle space and micro and macro-habitat use to inform conservation efforts. This study used VHF radiotelemetry and GPS data loggers to examine box turtle space and habitat use in North Texas. Box turtle home range sizes averaged 6.6ha (range = 0.79 - 18.08, n = 23), and males (n = 9) had larger home ranges than females (n = 14; W = 31.5, P = 0.05). Home range size was best explained by a combination of variables including sex and body size, but overall, home ranges that consisted of higher percentages of suitable box turtle habitat were smaller. Box turtles used deciduous forest more than expected and wetlands less than expected by chance (Fisher's exact test, P < 0.0001). The most informative variable for box turtle macrohabitat selection was NDVI. Box turtles selected microhabitats with a higher percent litter (t = -2.16, P < 0.05) and understory cover (t = -5.03, P < 0.05). The results of CART analysis showed the nested importance of macro- and microhabitat and identified …

The American Kestrel (Falco sparverius) is the smallest and most abundant falcon in North America with a wide geographic range. Unfortunately, surveys have suggested that some kestrel populations have been in decline since the 1950s, though the nominal causes of this decline are unknown. Migratory movement patterns and connectivity have yet to be established for any population of migratory kestrels. In Chapter 2, I investigated methods for attaching migration trackers to kestrels. Specifically, I showed that leg-loop style harnesses may have negatively affected return rates whereas backpack harnesses did not. Based on these results, I recommend that backpack-style Teflon harnesses is the safest and most effective method for attaching tracking devices to small raptors. In Chapter 3, I quantified survivorship for kestrels wintering in north Texas to identify the timing of kestrel mortality. Notably, I found that juvenile kestrels had similar annual survival rates as adults (81.6% versus 79.5%). High overwintering survival in north Texas indicated that once kestrels arrived on their wintering grounds, they were highly likely to survive to spring migration. In Chapter 4, I investigated pairing behaviors previously undocumented in wintering kestrels. I found that winter pairing was relatively common, but more prevalent in urban environments than …

There has been a rapid surge toward "organic" products devoid of GMOs, MSGs, and other common compounds found in processed foods that continue to indicate an association with an increased risk for disease. These consumers seek nutrients and vitamins that are lacking in their diet and lifestyle in the form of nutraceuticals for disease prevention and treatment as well as overall lifestyle enhancement. However, these products generally lack clinical evidence as well as legal definition. Due to this ambiguity, nutraceuticals are neither considered a food product nor a pharmaceutical product. Furthermore, due to their alleged natural properties allowing for safe, therapeutic effects, nutraceuticals are being eagerly sought after by consumers in the place of pharmaceuticals. Additionally, since nutraceutical substances are "naturally" derived, there is a general lack of regulation regarding the manufacturing and distribution process. This mismanagement leads to lack of quality assurance (QA) and quality control (QC) protocols strictly implemented to define appropriate production and storage parameters. Without these critical measures, consumers are subjected to contamination of their products resulting from improper storage conditions and unmanaged production. These contaminants often include heavy metal impurities, pesticides, bacterial activity, and may also be adulterated with illicit drugs, all leading to detrimental …

Light microscopy is inherently limited in resolution by properties of light such as diffraction and interference to 170-250 nm. Expansion microscopy is a quickly-developing method which achieves super-resolution by using a swellable hydrogel to physically expand biological samples themselves, rather than depending on the properties of fluorophores. This thesis demonstrates that expansion microscopy is a feasible means for achieving super-resolution in transmitted light microscopy modes. Though it has only been used for fluorescence imaging in the past, here I show that samples prepared for expansion microscopy—including liver tissue slices and myofibrillar bundles—are observable using transmitted light. While the majority of the original sample material is removed in the expansion process, the hydrogel retains visible evidence of these samples. These demonstrate increased detail under brightfield microscopy that is useful for characterization. Sarcomeric regions are identifiable by this method and are confirmed by fluorescence imaging. Thus, expansion microscopy is a means to bring super-resolution to transmitted light imaging and is entirely compatible with fluorescence for the localization of proteins of interest.

In Medicago truncatula, the MtNPF1.7 transporter has been shown to be essential for root morphology and nodulation development. The allelic MtNPF1.7 mutants, Mtnip-1 (A497V), Mtnip-3 (E171K), and Mtlatd (W341STOP), show altered lateral root growth and compromised legume-rhizobium symbiosis. To assess the role of a series of distinct amino acids in the transporter's function, in silico structural predictions were combined with in planta complementation of the severely defective Mtnip-1 mutant plants. The findings support hypotheses about the functional importance of the ExxE(R/K) motif including an essential role for the first glutamic acid of the motif in proton(s) and possibly substrate transport. The results also question the existence of a putative TMH4-TMH10 salt bridge, which may not form in MtNPF1.7. Results reveal that a motif conserved among MFS proteins, Motif A, is essential for function. Hypothetically, the Motif A participates in intradomain packing of transmembrane helices and stabilizing one conformation during transport. The mutated valine (A497V) in Mtnip-1 may interfere with the lateral helix. Mutating a residue (L253) on the lateral helix with reduced side chain restored Mtnip-1 function. The predicted residue (Q351) for substrate binding is not essential for protein function. To probe the possibility that MtNPF1.7 transports auxin, two heterologous …

Research into the mechanism of symbiotic nitrogen fixation between legumes and rhizobia involves a complex interaction between the organisms, and many genes involved in this remain either uncharacterized or undiscovered. Using forward genetics, mutant plant lines are screened to find new genes without reliance on software-based gene prediction. A large population of Tnt1-mutagenized Medicago truncatula lines is used for this purpose. Herein, the aid of tools like whole genome sequencing (WGS) in this process is explored so that new methods and tools are elucidated. The use of WGS data allows for rapid prediction of all insertions in the genome and has been shown to predict insertion locations that were missed by the TAIL-PCR-based Tnt1 mutant database already in existence. This WGS strategy has been successfully used to find the causal mutations in multiple plant lines. Two WGS strategies are used to analyze insertions in nine sequenced lines and compared with each other and the existing Tnt1 mutant database. It appears that using either WGS method will yield similar results, but the TAIL-PCR-based predictions have much less overlap. The use of the latest R108 genome appears to decrease the degree of disagreement between the methods, while the correlation in the A17 …

The process of symbiotic nitrogen fixation (SNF) in legume root nodules requires the channeling and exchange of nutrients within and between the host plant cells and between the plant cells and their resident rhizobia. Using a forward genetics approach in the Medicago truncatula Tnt1 mutant population followed by whole genome sequencing, two putative sulfate transporter genes, MtSULTR3;5 and MtSULTR3;4b, were identified. To support the hypothesis that the defective putative sulfate transporter genes were the causative mutation for the mutants' phenotypes, the M. truncatula Tnt1 population was successfully reverse screened to find other mutant alleles of the genes. The F2 progeny of mutants backcrossed with wildtype R108 demonstrated co-segregation of mutant phenotypes with the mutant alleles confirming that the mutated mtsultr3;5 and mtsultr3;4b genes were the cause of defective SNF in the mutant lines mutated in the respective genes. This finding was further established for mtsultr3;4b by successful functional complementation of a mutant line defective in the gene with the wildtype copy of MtSULTR3;4b. A MtSULTR3;4b promoter-GUS expression experiment indicated MtSULTR3;4b expression in the vasculature and infected and uninfected plant cells of root nodules. MtSULTR3;4b was found to localize to the autophagosome membrane when expressed in Nicotiana benthamiana. A transcriptomics study …

This work explores potential distortions created by race and ethnicity on the visualization, interpretation, and understanding of the spatial distribution of suicide in the United States. Due to radically different suicide rates among racial/ethnic groups, traditional crude or age-adjusted rates may introduce statistical confounding in both linear and spatial models. Using correlation, choropleth mapping, hot spot analysis, and location-allocation modeling, this work shows how traditional methods of health system planning may unintentionally overlook elevated risk in minority-dominated areas like inner cities, the Texas/Mexico border region, and the Deep South. The final chapter introduces a simulation protocol for examining potential distortions in datasets to identify spatial and non-spatial distortions created by the underlying population composition. Methodologically, this dissertation contributes to the discourse on place context versus population composition. More generally, this research points to potential hazards to creating a more inclusive and equitable healthcare system.

In this study, we have developed a novel way of generating and exposing biological organisms (both prokaryotic and eukaryotic) to silver nanoparticles (AgNPs) and studying the biochemical changes induced by these particles. We analyzed the various organs of Wistar rats for localization and quantification of these particles using mass spectrometric and molecular biological techniques. Highest levels of AgNP was found in the lung tissue in addition to being present in the liver and kidneys. Analysis of the of the blood plasma from AgNP exposed rats revealed elevated levels of glutathione-disulfide, which is indicative of reactive oxygen species (ROS) generation, which was further validated using ROS specific immunofluorescence staining of liver tissue. Quantification of blood lactate levels of the AgNP exposed rats showed increased lactate levels, which is indicative of anaerobic respiration and may result from AgNP-induced oxidative stress. Further analysis of bone marrow cells from AgNP exposed rats showed a higher number of micronuclei formation in developing erythrocytes and bone marrow cytotoxicity. Finally, analysis of the genes involved in the renin-angiotensin system (RAS) and inflammatory response revealed upregulation in transcript levels of many of these important genes in the liver tissue. Taken together, our study provides an initial road map …

Trait-based approaches are useful in ecological research because of their potential ability to predict species responses from patterns present in the community and to infer mechanisms driving community assembly. Current approaches for fishes are lacking traits across all five fundamental niche dimensions (i.e. habitat, life history, trophic, metabolic and defense). This study quantified a broad range of fish functional traits across all five niche dimensions (commonly used traits and novel traits), quantified intra- and interspecific variation for each trait, tested for relationships among traits within and among niche dimensions, tested for phylogenetic conservatism of traits and assessed trait-environment relationships for a subset of these traits under two different contexts. Approximately one third of the quantified traits exhibited greater intraspecific variation than interspecific variation and were not included in subsequent analyses. There were similarities between phylogeny and trait dendrograms for all traits, and habitat, metabolic and defense traits. The traits identified in chapter 2 were able to explain species responses during different flow periods in two intermittent streams as well as species-specific differences in host microbiome at the onset of drought in one intermittent stream. The novel traits identified in chapter 2 did contribute to our understanding of the community assembly …

Environmental air pollution is one risk factor associated with the onset and progression of multiple sclerosis (MS). In this project, we investigated the effects of ubiquitous traffic-generated pollutants, namely a mixture of gasoline and diesel vehicle exhaust (MVE), on signaling pathways associated with the pathophysiology of MS in the central nervous system (CNS) of either ovary intact (ov+) or ovariectomized (ov-) female Apolipoprotein (Apo) E-/-. Specifically, we investigated whether a subchronic inhalation exposure to MVE (200 PM μg/m3; 6 hr/d, 7d/wk, 30d) vs. filtered air (FA) controls altered myelination, T cell infiltration, blood-brain barrier (BBB) integrity, or production of reactive oxygen species (ROS) and expression of neuroinflammation markers in the CNS ov+ and ov- Apo E-/- mice. Our results revealed that inhalation exposure to MVE resulted in increased demyelination and CD4+ and CD8+ T cell infiltration, associated with alterations in BBB integrity. Disruption of the BBB was evidenced by decreased tight junction (TJ) protein expression, increased matrix metalloproteinase (MMPs) activity, and increased permeability of immunoglobin (Ig) G, which were more pronounced in the MVE ov- group. Moreover, MVE-exposure also promoted ROS and neuroinflammatory signaling in the CNS of ov+ and ov- mice, compared to FA groups. To analyze mechanisms that …

In this study, I examined the use of mouse (Mus musculus) Fat Specific Protein 27 (FSP27) ectopically expressed in Arabidopsis thaliana and Nicotiana benthamiana as a means to increase lipid droplet (LD) presence in plant tissues. In mammalian cells, this protein induces cytoplasmic LD clustering and fusion and helps prevent breakdown of LDs contributing to the large, single LD that dominates adipocytes. When expressed in Arabidopsis thaliana and Nicotiana benthamiana, FSP27 retained its functionality and supported the accumulation of numerous and large cytoplasmic LDs, although it failed to produce the large, single LD that typifies adipose cells. FSP27 has no obvious homologs in plants, but a search for possible distant homologs in Arabidopsis returned a Tudor/PWWP/MBT protein coded for by the gene AT1G80810 which for the purposes of this study, we have called LIPID REGULATORY TUDOR DOMAIN CONTAINING GENE 1 (LRT1). As a possible homolog of FSP27, LRT1 was expected to have a positive regulatory effect on LDs in cells. Instead, a negative regulatory effect was observed in which disruption of the gene induced an accumulation of cytoplasmic LDs in non-seed tissue. A study of lrt1 mutants demonstrated that disruption this gene is the causal factor of the cytoplasmic LD …

The purpose of this study was to investigate the effects of Pb and hypoxia co-exposure on Pb toxicity and Ca homeostasis in early life stage (ELS) zebrafish (Danio rerio). Previous evidence indicates that exposure of ELS zebrafish to hypoxia (~20% air saturation) reduces Ca uptake, likely through down-regulation of the apical epithelial Ca channel (ECaC). Considering that Pb and Ca are known antagonists and compete for uptake pathways, it was hypothesized that co-exposure of Pb with hypoxia would decrease Pb toxicity by reducing Pb uptake (likely mediated through a reduced number of ECaCs). However, it was shown that at 96 hpf, whole body accumulation of both Pb and Ca was lower at 40% air saturation compared to 100% and 20% air saturation. This result closely aligned with the 96h LC50 results which showed the highest mortality of zebrafish at 40% compared to the other air saturation levels. This suggests that toxicity is likely the result of exacerbated hypocalcemia at 40% air saturation due to both Pb competition for Ca binding to Ca uptake channels/transporters, such as ECaC, and potentially reduced expression of such channels/transporters in response to this level of hypoxia. Overall, it appears that ELS zebrafish respond differentially to …