Matching Items (43)
Description
Cuticular hydrocarbons (CHCs) play a crucial role in social insect recognition systems. In this study we investigated mate choice in the red harvester ant, Pogonomyrmex barbatus. In Phoenix, this species has two lineages, J1 and J2, which look identical, but are genetically isolated. In the genetic caste determination (GCD) system workers and queens are determined by their genotype (i.e., workers develop from interlineage crosses, queens from intralineage crosses). As such, J1 and J2 lineages are dependent on each other in order for colonies to produce both workers and reproductive queens. Given their genetic isolation and interdependence, we hypothesized that the CHCs of alate males and queens are affected by lineage, and that differences in the CHC profile are used for mate recognition. We tested these hypotheses by analyzing the lineage distributions of actively mating pairs (n=65), and compared them with the overall distribution of male and female sexuals (n=180). We additionally analyzed the five most abundant CHC compounds for 20 of the actively mating P. barbatus alate male and queen pairs to determine how variable the two lineages are between each sex. We found that mating pair distributions did not significantly differ from those expected under a random mating system (�2= 1.4349, P= 0.6973), however, CHC profiles did differ between J1 and J2 lineages and sexes for the five most abundant CHC compounds. Our results show that random mating is taking place in this population, however given the differences observed in CHC profiles, mate recognition could be taking place.
ContributorsTula Del Moral Testai, Pedro Rafael (Co-author) / Cash, Elizabeth (Co-author) / Gadau, Juergen (Thesis director) / Liebig, Juergen (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / School of Life Sciences (Contributor)
Created2014-05
Description
I tested the hypothesis that in mature colonies of the seed harvester Pogonomyrmex californicus ant species, paired pleometrotic queens would produce workers more efficiently after a massive removal of their work force than haplometrotic queens, paired pleometrotic with haplometrotic queens, and single pleometrotic queens. I suggested that the paired pleometrotic queens would have an advantage of cooperating together in reproducing more workers quicker than the other conditions to make up for the lost workers. This would demonstrate a benefit that pleometrosis has over haplometrosis for mature colonies, which would explain why pleometrosis continues for P.californicus after colony foundation. After removing all but twenty workers for every colony, I took pictures and counted the emerging brood for 52 days. Analyses showed that the paired pleometrotic queens and the haplometrotic queens both grew at an equally efficient rate and the paired pleometrotic and haplometrotic queens growing the least efficiently. However, the results were not significant and did not support the hypothesis that paired pleometrotic queens recover from worker loss more proficiently than other social systems.
ContributorsFernandez, Marisa Raquel (Author) / Fewell, Jennifer (Thesis director) / Gadau, Juergen (Committee member) / Haney, Brian (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / Department of Psychology (Contributor)
Created2014-05
Description
It is important to consider factors that contribute to successful fertilization and the development of viable offspring. Better understanding the factors that contribute to infertility can be used to assist in the development of viable offspring, especially for human beings looking to successfully reproduce. Identifying paternal effect genes, genes that come from the father, introduces more targets that can be manipulated to produce specific reproductive effects. Use of Drosophila melanogaster as a model to study reproduction has increased, in part, due to the use of the GAL4 system. In this system, the GAL4 gene encodes an 881 amino acid protein that binds to the 4-site Upstream Activating Sequence (UAS) to induce transcription of the gene of interest. These sequences constitute the two components of the system: the driver (GAL4) and the responder (gene of interest) \u2014 each of which is maintained as a separate parental line. Effects of the GAL4 driver line "driving" transcription of the responder can be assessed by examining the offspring. One of the more common uses of the GAL4 system involves analyzing phenotypic effects of reducing or eliminating expression of a target gene through the induction of RNAi transcription, which often results in toxicity, lethality, or reduced viability. Utilizing these principles, we strove to demonstrate the effect of knocking down the expression of testis-specific sperm-leucyl-aminopeptidases gene CG13340 on progeny by inducing expression of RNAi with two distinct GAL4 driver lines - one with a nonspecific actin-binding activation sequence and the other with a testis-specific activation sequence. Comparison of both GAL4 driver lines to crosses using N01 wild type ("wt") flies verify that inducing RNAi transcription using the GAL4 system results in reduction of proper offspring development. Further studies using D. melanogaster and the GAL4 system can improve knowledge of factors contributing to male fertility and also be applied to better understand mammalian, specifically human, fertility.
ContributorsEvans, Donna Marie (Author) / Karr, Timothy L. (Thesis director) / Roland, Kenneth (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / Department of English (Contributor)
Created2014-05
Description
Wolbachia is a genus of obligately intracellular bacterial endosymbionts of arthropods and nematodes, infecting up to 66% of all such species. In order to ensure its transmission, it may modify host reproduction by inducing one of four phenotypes: cytoplasmic incompatibility, feminization of genetic males, killing of male embryos, and induction of thelytokous parthenogenesis. This investigation was a characterization of the so-far unexamined Wolbachia infection of Pogonomyrmex ants. Five main questions were addressed: whether Wolbachia infection rates vary between North and South America, whether infection rates are dependent on host range, whether Wolbachia affects the caste determination of P. barbatus, whether infection rates in Pogonomyrmex are similar to those of other ants, and whether Wolbachia phylogeny parallels the phylogeny of its Pogonomyrmex hosts. Using PCR amplification of the wsp, ftsZ, and gatB loci, Wolbachia infections were detected in four of fifteen Pogonomyrmex species (26.7%), providing the first known evidence of Wolbachia infection in this genus. All infected species were from South America, specifically Argentina. Therefore, Wolbachia has no role in the caste determination of the North American species P. barbatus. Additionally, while it appears that the incidence of Wolbachia in Pogonomyrmex may be limited to South America, host range did not correlate with infection status. The incidence of Wolbachia in Pogonomyrmex as a whole was similar to that of invasive Solenopsis and Linepithema species, but not to Wasmannia auropunctata or Anoplolepis gracilipes, which retain Wolbachia infection in non-native locations. This suggests that there may be a parallel in Wolbachia infection spread in certain short-term models of species colonization and long-term models of genus radiation. Finally, there was no congruity between host and parasite phylogeny according to maximum likelihood analyses, necessarily due to horizontal transfer of Wolbachia between hosts and lateral gene transfer between Wolbachia strains within hosts.
ContributorsHarris, Alexandre Marm (Author) / Gadau, Juergen (Thesis director) / Martin, Thomas (Committee member) / Helmkampf, Martin Erik (Committee member) / Barrett, The Honors College (Contributor) / Computer Science and Engineering Program (Contributor) / School of Life Sciences (Contributor)
Created2014-05
Description
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, is the 10th leading cause of death, worldwide. The prevalence of drug-resistant clinical isolates and the paucity of newly-approved antituberculosis drugs impedes the successful eradication of Mtb. Bacteria commonly use two-component systems (TCS) to sense their environment and genetically modulate adaptive responses. The prrAB TCS is essential in Mtb, thus representing an auspicious drug target; however, the inability to generate an Mtb ΔprrAB mutant complicates investigating how this TCS contributes to pathogenesis. Mycobacterium smegmatis, a commonly used M. tuberculosis genetic surrogate was used here. This work shows that prrAB is not essential in M. smegmatis. During ammonium stress, the ΔprrAB mutant excessively accumulates triacylglycerol lipids, a phenotype associated with M. tuberculosis dormancy and chronic infection. Additionally, triacylglycerol biosynthetic genes were induced in the ΔprrAB mutant relative to the wild-type and complementation strains during ammonium stress. Next, RNA-seq was used to define the M. smegmatis PrrAB regulon. PrrAB regulates genes participating in respiration, metabolism, redox balance, and oxidative phosphorylation. The M. smegmatis ΔprrAB mutant is compromised for growth under hypoxia, is hypersensitive to cyanide, and fails to induce high-affinity respiratory genes during hypoxia. Furthermore, PrrAB positively regulates the hypoxia-responsive dosR TCS response regulator, potentially explaining the hypoxia-mediated growth defects in the ΔprrAB mutant. Despite inducing genes encoding the F1F0 ATP synthase, the ΔprrAB mutant accumulates significantly less ATP during aerobic, exponential growth compared to the wild-type and complementation strains. Finally, the M. smegmatis ΔprrAB mutant exhibited growth impairment in media containing gluconeogenic carbon sources. M. tuberculosis mutants unable to utilize these substrates fail to establish chronic infection, suggesting that PrrAB may regulate Mtb central carbon metabolism in response to chronic infection. In conclusion, 1) prrAB is not universally essential in mycobacteria; 2) M. smegmatis PrrAB regulates genetic responsiveness to nutrient and oxygen stress; and 3) PrrAB may provide feed-forward control of the DosRS TCS and dormancy phenotypes. The data generated in these studies provide insight into the mycobacterial PrrAB TCS transcriptional regulon, PrrAB essentiality in Mtb, and how PrrAB may mediate stresses encountered by Mtb during the transition to chronic infection.
ContributorsMaarsingh, Jason (Author) / Haydel, Shelley E (Thesis advisor) / Roland, Kenneth (Committee member) / Sandrin, Todd (Committee member) / Bean, Heather (Committee member) / Arizona State University (Publisher)
Created2019
Description
The ability to tolerate bouts of oxygen deprivation varies tremendously across the animal kingdom. Adult humans from different regions show large variation in tolerance to hypoxia; additionally, it is widely known that neonatal mammals are much more tolerant to anoxia than their adult counterparts, including in humans. Drosophila melanogaster are very anoxia-tolerant relative to mammals, with adults able to survive 12 h of anoxia, and represent a well-suited model for studying anoxia tolerance. Drosophila live in rotting, fermenting media and a result are more likely to experience environmental hypoxia; therefore, they could be expected to be more tolerant of anoxia than adults. However, adults have the capacity to survive anoxic exposure times ~8 times longer than larvae. This dissertation focuses on understanding the mechanisms responsible for variation in survival from anoxic exposure in the genetic model organism, Drosophila melanogaster, focused in particular on effects of developmental stage (larval vs. adults) and within-population variation among individuals.
Vertebrate studies suggest that surviving anoxia requires the maintenance of ATP despite the loss of aerobic metabolism in a manner that prevents a disruption of ionic homeostasis. Instead, the abilities to maintain a hypometabolic state with low ATP and tolerate large disturbances in ionic status appear to contribute to the higher anoxia tolerance of adults. Furthermore, metabolomics experiments support this notion by showing that larvae had higher metabolic rates during the initial 30 min of anoxia and that protective metabolites were upregulated in adults but not larvae. Lastly, I investigated the genetic variation in anoxia tolerance using a genome wide association study (GWAS) to identify target genes associated with anoxia tolerance. Results from the GWAS also suggest mechanisms related to protection from ionic and oxidative stress, in addition to a protective role for immune function.
Vertebrate studies suggest that surviving anoxia requires the maintenance of ATP despite the loss of aerobic metabolism in a manner that prevents a disruption of ionic homeostasis. Instead, the abilities to maintain a hypometabolic state with low ATP and tolerate large disturbances in ionic status appear to contribute to the higher anoxia tolerance of adults. Furthermore, metabolomics experiments support this notion by showing that larvae had higher metabolic rates during the initial 30 min of anoxia and that protective metabolites were upregulated in adults but not larvae. Lastly, I investigated the genetic variation in anoxia tolerance using a genome wide association study (GWAS) to identify target genes associated with anoxia tolerance. Results from the GWAS also suggest mechanisms related to protection from ionic and oxidative stress, in addition to a protective role for immune function.
ContributorsCampbell, Jacob B (Author) / Harrison, Jon F. (Thesis advisor) / Gadau, Juergen (Committee member) / Call, Gerald B (Committee member) / Sweazea, Karen L (Committee member) / Rosenberg, Michael S. (Committee member) / Arizona State University (Publisher)
Created2018
Description
Amongst the most studied of the social insects, the honey bee has a prominent place due to its economic importance and influence on human societies. Honey bee colonies can have over 50,000 individuals, whose activities are coordinated by chemical signals called pheromones. Because these pheromones are secreted from various exocrine glands, the proper development and function of these glands are vital to colony dynamics. In this thesis, I present a study of the developmental ontogeny of the exocrine glands found in the head of the honey bee. In Chapter 2, I elucidate how the larval salivary gland transitions to an adult salivary gland through apoptosis and cell growth, differentiation and migration. I also explain the development of the hypopharyngeal and the mandibular gland using apoptotic markers and cytoskeletal markers like tubulin and actin. I explain the fundamental developmental plan for the formation of the glands and show that apoptosis plays an important role in the transformation toward an adult gland.
ContributorsNath, Rachna (Author) / Gadau, Juergen (Thesis advisor) / Rawls, Alan (Committee member) / Harrison, Jon (Committee member) / Arizona State University (Publisher)
Created2018
Description
The emergence of invasive non-Typhoidal Salmonella (iNTS) infections belonging to sequence type (ST) 313 are associated with severe bacteremia and high mortality in sub-Saharan Africa. Distinct features of ST313 strains include resistance to multiple antibiotics, extensive genomic degradation, and atypical clinical diagnosis including bloodstream infections, respiratory symptoms, and fever. Herein, I report the use of dynamic bioreactor technology to profile the impact of physiological fluid shear levels on the pathogenesis-related responses of ST313 pathovar, 5579. I show that culture of 5579 under these conditions induces profoundly different pathogenesis-related phenotypes than those normally observed when cultures are grown conventionally. Surprisingly, in response to physiological fluid shear, 5579 exhibited positive swimming motility, which was unexpected, since this strain was initially thought to be non-motile. Moreover, fluid shear altered the resistance of 5579 to acid, oxidative and bile stress, as well as its ability to colonize human colonic epithelial cells. This work leverages from and advances studies over the past 16 years in the Nickerson lab, which are at the forefront of bacterial mechanosensation and further demonstrates that bacterial pathogens are “hardwired” to respond to the force of fluid shear in ways that are not observed during conventional culture, and stresses the importance of mimicking the dynamic physical force microenvironment when studying host-pathogen interactions. The results from this study lay the foundation for future work to determine the underlying mechanisms operative in 5579 that are responsible for these phenotypic observations.
ContributorsCastro, Christian (Author) / Nickerson, Cheryl A. (Thesis advisor) / Ott, C. Mark (Committee member) / Roland, Kenneth (Committee member) / Barrila, Jennifer (Committee member) / Arizona State University (Publisher)
Created2016
Description
Invasive salmonellosis caused by Salmonella enterica serovar Typhimurium ST313 is a major health crisis in sub-Saharan Africa, with multidrug resistance and atypical clinical presentation challenging current treatment regimens and resulting in high mortality. Moreover, the increased risk of spreading ST313 pathovars worldwide is of major concern, given global public transportation networks and increased populations of immunocompromised individuals (as a result of HIV infection, drug use, cancer therapy, aging, etc). While it is unclear as to how Salmonella ST313 strains cause invasive disease in humans, it is intriguing that the genomic profile of some of these pathovars indicates key differences between classic Typhimurium (broad host range), but similarities to human-specific typhoidal Salmonella Typhi and Paratyphi. In an effort to advance fundamental understanding of the pathogenesis mechanisms of ST313 in humans, I report characterization of the molecular genetic, phenotypic and virulence profiles of D23580 (a representative ST313 strain). Preliminary studies to characterize D23580 virulence, baseline stress responses, and biochemical profiles, and in vitro infection profiles in human surrogate 3-D tissue culture models were done using conventional bacterial culture conditions; while subsequent studies integrated a range of incrementally increasing fluid shear levels relevant to those naturally encountered by D23580 in the infected host to understand the impact of biomechanical forces in altering these characteristics. In response to culture of D23580 under these conditions, distinct differences in transcriptional biosignatures, pathogenesis-related stress responses, in vitro infection profiles and in vivo virulence in mice were observed as compared to those of classic Salmonella pathovars tested.
Collectively, this work represents the first characterization of in vivo virulence and in vitro pathogenesis properties of D23580, the latter using advanced human surrogate models that mimic key aspects of the parental tissue. Results from these studies highlight the importance of studying infectious diseases using an integrated approach that combines actions of biological and physical networks that mimic the host-pathogen microenvironment and regulate pathogen responses.
Collectively, this work represents the first characterization of in vivo virulence and in vitro pathogenesis properties of D23580, the latter using advanced human surrogate models that mimic key aspects of the parental tissue. Results from these studies highlight the importance of studying infectious diseases using an integrated approach that combines actions of biological and physical networks that mimic the host-pathogen microenvironment and regulate pathogen responses.
ContributorsYang, Jiseon (Author) / Nickerson, Cheryl A. (Thesis advisor) / Chang, Yung (Committee member) / Stout, Valerie (Committee member) / Ott, C Mark (Committee member) / Roland, Kenneth (Committee member) / Barrila, Jennifer (Committee member) / Arizona State University (Publisher)
Created2015
Description
During the 1960s, the long-standing idea that traits or behaviors could be
explained by natural selection acting on traits that persisted "for the good of the group" prompted a series of debates about group-level selection and the effectiveness with which natural selection could act at or across multiple levels of biological organization. For some this topic remains contentious, while others consider the debate settled, even while disagreeing about when and how resolution occurred, raising the question: "Why have these debates continued?"
Here I explore the biology, history, and philosophy of the possibility of natural selection operating at levels of biological organization other than the organism by focusing on debates about group-level selection that have occurred since the 1960s. In particular, I use experimental, historical, and synthetic methods to review how the debates have changed, and whether different uses of the same words and concepts can lead to different interpretations of the same experimental data.
I begin with the results of a group-selection experiment I conducted using the parasitoid wasp Nasonia, and discuss how the interpretation depends on how one conceives of and defines a "group." Then I review the history of the group selection controversy and argue that this history is best interpreted as multiple, interrelated debates rather than a single continuous debate. Furthermore, I show how the aspects of these debates that have changed the most are related to theoretical content and empirical data, while disputes related to methods remain largely unchanged. Synthesizing this material, I distinguish four different "approaches" to the study of multilevel selection based on the questions and methods used by researchers, and I use the results of the Nasonia experiment to discuss how each approach can lead to different interpretations of the same experimental data. I argue that this realization can help to explain why debates about group and multilevel selection have persisted for nearly sixty years. Finally, the conclusions of this dissertation apply beyond evolutionary biology by providing an illustration of how key concepts can change over time, and how failing to appreciate this fact can lead to ongoing controversy within a scientific field.
explained by natural selection acting on traits that persisted "for the good of the group" prompted a series of debates about group-level selection and the effectiveness with which natural selection could act at or across multiple levels of biological organization. For some this topic remains contentious, while others consider the debate settled, even while disagreeing about when and how resolution occurred, raising the question: "Why have these debates continued?"
Here I explore the biology, history, and philosophy of the possibility of natural selection operating at levels of biological organization other than the organism by focusing on debates about group-level selection that have occurred since the 1960s. In particular, I use experimental, historical, and synthetic methods to review how the debates have changed, and whether different uses of the same words and concepts can lead to different interpretations of the same experimental data.
I begin with the results of a group-selection experiment I conducted using the parasitoid wasp Nasonia, and discuss how the interpretation depends on how one conceives of and defines a "group." Then I review the history of the group selection controversy and argue that this history is best interpreted as multiple, interrelated debates rather than a single continuous debate. Furthermore, I show how the aspects of these debates that have changed the most are related to theoretical content and empirical data, while disputes related to methods remain largely unchanged. Synthesizing this material, I distinguish four different "approaches" to the study of multilevel selection based on the questions and methods used by researchers, and I use the results of the Nasonia experiment to discuss how each approach can lead to different interpretations of the same experimental data. I argue that this realization can help to explain why debates about group and multilevel selection have persisted for nearly sixty years. Finally, the conclusions of this dissertation apply beyond evolutionary biology by providing an illustration of how key concepts can change over time, and how failing to appreciate this fact can lead to ongoing controversy within a scientific field.
ContributorsDimond, Christopher C (Author) / Collins, James P. (Thesis advisor) / Gadau, Juergen (Committee member) / Laubichler, Manfred (Committee member) / Armendt, Brad (Committee member) / Lynch, John (Committee member) / Arizona State University (Publisher)
Created2014