Biology Master's Theses Copyright (c) 2013 Northeastern University All rights reserved. http://iris.lib.neu.edu/biology_theses Recent documents in Biology Master's Theses en-us Sat, 18 May 2013 01:40:29 PDT 3600 Activation of phenotypic subpopulations in response to ciprofloxacin treatment in acinetobacter baumannii http://iris.lib.neu.edu/biology_theses/25 http://iris.lib.neu.edu/biology_theses/25 Thu, 16 May 2013 12:28:48 PDT The desiccation-resistant pathogen, Acinetobacter baumannii, has spread swiftly through hospitals worldwide. Favoring chromosomal insertions and rearrangements, A. baumannii isolates are quickly becoming pandrug resistant. We have recently demonstrated that A. baumannii regulates the expression of multiple copies of genes encoding error-prone DNA polymerases, which seem to be responsible for DNA damage- or desiccation-induced mutagenesis, leading to antibiotic resistance. Here, we explore expression of the DNA damage-inducible system in A. baumannii, using transcriptional reporters fused to green fluorescent protein for selected DNA damage response genes. The expression of these genes in response to treatment with the antibiotic, ciprofloxacin, was then analyzed... ]]> Ashley Erin MacGuire The role of seasonality, seaweed traits, and seaweed-herbivore interactions in nutrient cycling in the southern Gulf of Maine http://iris.lib.neu.edu/biology_theses/24 http://iris.lib.neu.edu/biology_theses/24 Tue, 14 May 2013 11:42:56 PDT Environmental fluctuations associated with both natural events and anthropogenic impacts can appreciably alter the functioning of ecosystems. For example, in the Gulf of Maine, there is substantial spatial and temporal variation in availability of nutrients that fuel primary production. Macroalgae are important primary producers in intertidal and shallow benthic habitats, and they play essential roles in absorbing nutrients (e.g., inorganic C, N, and P) and mediating their availability (e.g., as organic C, N, and P) to the communities that they support. The ability of macroalgae to take up nutrients depends on nutrient availability. However, sometimes a nutrient in short supply... ]]> Valerie Catlin Perini Parental provisioning in the face of pathogenic presssures: contributions to offspring in a social insect, the dampwood termite (Zootermopsis angusticollis) http://iris.lib.neu.edu/biology_theses/23 http://iris.lib.neu.edu/biology_theses/23 Thu, 09 May 2013 09:49:30 PDT Social insects (i.e. ants and termites) are excellent candidate species to address questions about parental provisioning in the face of pathogenic constraints. Parental investment theory holds that adults that anticipate the future needs of their offspring based on their current surroundings and conditions will allocate resources to their young accordingly. The specific focus of this research is trans-generational immunity, the phenomenon whereby parents provision their offspring with raw materials that confer their progeny protection against pathogenic microbes. Using the dampwood termite, Zootermopsis angusticollis, I tackled the question of whether parents contribute differently to offspring in the face of different pathogenic... ]]> Andrielle N. Swaby Exploring the early effects of AP endonuclease 1 knockdown in zebrafish embryogenesis http://iris.lib.neu.edu/biology_theses/22 http://iris.lib.neu.edu/biology_theses/22 Tue, 09 Apr 2013 08:12:56 PDT AP Endonuclease 1 (Apex1) is a major player in the base excision repair (BER) pathway, which accounts for the majority of oxidative DNA damage repair in eukaryotic cells. Loss of Apex1 in developing vertebrate embryos, whether by artificial knockdown or genetic knockout, is lethal and halts development near the onset of gastrulation. To date, no one has successfully cultured Apex1 -/- cells from any source, suggesting its vital role for Apex1. Our lab has recently discovered a regulatory relationship between Apex1 and the cAMP response element binding (Creb) complex in zebrafish and mice. Partial knockdown of Apex1 using morpholino oligonucleotides... ]]> Benjamin Snow Dietary contribution of polychlorinated biphenyl contaminated Ulva to Fundulus heteroclitus in the New Bedford Harbor, MA, Superfund site http://iris.lib.neu.edu/biology_theses/21 http://iris.lib.neu.edu/biology_theses/21 Wed, 06 Mar 2013 07:35:48 PST Macroalgal blooms are associated with a wide range of negative consequences impacting the growth and survival of primary producers and benthic consumers, but are generally not viewed as serious threats to higher trophic level consumers. A recently discovered polychlorinated biphenyl (PCB) contaminated Ulva bloom located in the New Bedford Harbor (NBH), MA, Superfund site challenges this idea, but its potential to increase the bioavailability of PCBs to the upper NBH food web has not previously been evaluated. In this investigation, the dietary contribution of Ulva to the common NBH mid-trophic consumer Fundulus heteroclitus was assessed between fall 2011 and fall... ]]> Elizabeth Sly Escherichia coli response to replication stress mediated by Hydroxyurea http://iris.lib.neu.edu/biology_theses/20 http://iris.lib.neu.edu/biology_theses/20 Fri, 01 Feb 2013 12:30:39 PST Error prone Y-family DNA polymerases in Escherichia coli, DNA polymerases IV and V, play a significant role in the cell's defense against exogenous and endogenous DNA damage. These polymerases are important for bypassing specific lesions present on the template DNA. We have shown (Godoy et al., 2006) that only E. coli cells expressing a carboxy-terminal truncated derivative of the catalytic subunit of DNA polymerase V, UmuC122, are resistant to the chemotherapeutic agent Hydroxyurea (HU). while umuC+ cells are highly HUS. Remarkably, umuC122::Tn5 cultures have a 100 fold elevated mutagenesis. HU inactivates class I ribonucleotide reductases (RNRs), enzymes responsible for the... ]]> Nicole Marie Connelly Influence of climate, fruit availability and nutritional content on bird selection of non-native, invasive (Frangula alnus) and native (Prunus serotina) fruit in eastern Massachusetts http://iris.lib.neu.edu/biology_theses/19 http://iris.lib.neu.edu/biology_theses/19 Wed, 12 Dec 2012 14:39:00 PST Second only to habitat destruction, the introduction of non-native, invasive species is a major threat to ecosystems and is exacerbated by global climate change resulting in a shift in plant phenology. By consuming fruit and defecating seeds, birds are a dispersal agent for many plant species, particularly non-native, invasive species. The avian use of non-native, invasive glossy buckthorn (Frangula alnus) fruit was examined and compared with use of native black cherry (Prunus serotina) fruit over a two year period in eastern Massachusetts. Using visual observations, apparent F. alnus and P. serotina fruit consumption by birds was observed and noted at... ]]> Elisabeth Jablonski Clark The nonconsumptive and consumptive effects of the invasive green crab (Carcinus maenas) on macroinfaunal diversity, abundance and ecosystem functioning in a New England salt marsh http://iris.lib.neu.edu/biology_theses/18 http://iris.lib.neu.edu/biology_theses/18 Fri, 07 Dec 2012 08:28:28 PST Traditional studies of trophic cascades have revealed how predators by limiting abundance of their prey, have positive indirect effects on basal resources. However, recent studies have shown that predators can also indirectly affect such resources without consuming their prey by way of anti-predator foraging adaptive behavior (nonconsumptive effects). For example, on rocky shores, waterborne risk cues from the predatory green crab (Carcinus maenas) cause strong trophic cascades by suppressing the grazing rate of the herbivorous snail, Littorina littorea, on algal resources. L. littorea is also an abundant herbivore in northern New England salt marshes but it is unknown whether C.... ]]> Genevieve Bernatchez Evaluation of hair follicles as a surrogate tissue for pharmacodynamics response in xenograft tumors http://iris.lib.neu.edu/biology_theses/17 http://iris.lib.neu.edu/biology_theses/17 Tue, 23 Oct 2012 10:10:29 PDT Identification of an easily accessible and pharmacodynamically robust surrogate tissue for tumor biopsies is essential for rapid drug development in oncology. Blood–borne markers are the gold standard for monitoring pharmacodynamics for many diseases, although they are not always relevant for many cancers. Plucked hair has gained attention as a surrogate tissue as it is an epithelial tissue similar to the origin of >80% of tumors, has good drug exposure and is highly proliferative as with many tumors. We have linked the pharmacodynamic response of hair follicles and tumors in vivo using a mouse xenograft model to facilitate the development of... ]]> Mary-Kamala Menon The roles of muscles in arm swing and thoracic rotation during walking http://iris.lib.neu.edu/biology_theses/16 http://iris.lib.neu.edu/biology_theses/16 Thu, 07 Jun 2012 05:17:28 PDT The functional role of arm swing during walking has been hypothesized to reduce net angular momentum and moment about the vertical axis, and to minimize metabolic costs of locomotion. Arm swing follows a specific timing pattern, with peak flexion occurring at the midpoint of stride. Recent studies have proposed that arm swing arises passively from driving forces imparted on the arm by thorax rotation and derived from energy input from the lower body. However, the passively driven hypothesis does not account for changes in arm swing timing that would occur with changes in stride frequency or inertia properties of the... ]]> Andrew K. Yegian Arm - Movements Gait in humans Zebrafish bloodthirsty: developmental expression and identification of the mammalian ortholog http://iris.lib.neu.edu/biology_theses/15 http://iris.lib.neu.edu/biology_theses/15 Tue, 06 Mar 2012 04:36:24 PST Blood disorders, such as anemias, are serious diseases in humans. Because the hematopoietic program is highly conserved among vertebrates, we are using fish models to isolate novel erythropoietic genes and to elucidate the functions of the encoded proteins. In this thesis, I describe experiments to examine the developmental expression patterns of the novel zebrafish gene, bloodthirsty (bty), and to identify its probable mammalian ortholog.

The novel gene bloodthirsty (bty) was discovered in a subtractive screen that isolated hematopoietic genes that were differentially expressed by the pronephric kidneys of the red-blood Antarctic rockcod, Notothenia coriiceps, and its white-blood relative, the icefish... ]]> Mo Hu erythropoiesis Zebra danio Characterization of the gene structure and biochemical properties of the C. elegans filamin orthologs FLN-1 and FLN-2 http://iris.lib.neu.edu/biology_theses/14 http://iris.lib.neu.edu/biology_theses/14 Tue, 22 Mar 2011 06:48:29 PDT Filamins are long, flexible, multi-domain proteins composed of an N-terminal actin-binding domain (ABD) followed by multiple immunoglobulin-like repeats (Ig-FLN). They function to anchor, organize and maintain the actin cytoskeleton, to provide scaffolds for signaling components, and to act as sensors for mechanical forces. In this study, we use a cDNA sequencing and bioinformatics approach to identify and describe the gene structure, expression patterns and phylogeny of the C. elegans filamin orthologs encoded by fln-1 and fln-2. We also used homology modeling to predict the protein structures. Our results reveal that C. elegans FLN-1 is well conserved at the sequence level... ]]> Christina DeMaso Caenorhabditis elegans - Phylogeny Genetic code Biochemical genetics Phenoloxidase activity in Isoptera: dynamics between life history traits and immunocompetence http://iris.lib.neu.edu/biology_theses/13 http://iris.lib.neu.edu/biology_theses/13 Mon, 07 Mar 2011 06:01:11 PST Insects are an evolutionarily and ecologically successful taxonomic group. To survive and be competitive, insects must have the ability to defend against the assault of pathogens and parasites. Arthropod immunity is comprised of two major components, the humoral and cellular responses. The latter is heavily dependent on the phenoloxidase cascade, although both components utilize this cascade. Phenoloxidase (PO) is a "versatile" enzyme, responsible for the process of melanization in arthropods. It plays a role in the sclerotization and tanning of newly molted exoskeleton while also being involved in several immune responses such as encapsulation, nodulation and wound healing. The quantification... ]]> Jennifer Lindsey Reichheld Termites - Ecophysiology Phylogeographic analysis reveals a deep lineage split within North Atlantic Littorina Saxatilis http://iris.lib.neu.edu/biology_theses/12 http://iris.lib.neu.edu/biology_theses/12 Fri, 04 Mar 2011 09:24:29 PST Phylogeographic studies provide critical insight into the evolutionary histories of model organisms; yet, to date, range-wide data are lacking for the rough periwinkle Littorina saxatilis, a classic example of marine sympatric speciation. I utilized mitochondrial DNA (mtDNA) sequence data to demonstrate that L. saxatilis is not monophyletic, but is comprised of two mtDNA lineages (I and II) that are shared with its sister-species L. arcana and L. compressa. Bayesian coalescent dating and phylogeographic patterns indicate that both L. saxatilis lineages (I and II) originated in the northeastern Atlantic, around the British Isles, approximately 0.64 Ma. Both lineages are now distributed... ]]> Meredith M. Doellman Littorina saxatilis--Evolution Mechanisms for maintaining stability in the helmeted guinea fowl Numida Meleagris when running on uneven terrain http://iris.lib.neu.edu/biology_theses/11 http://iris.lib.neu.edu/biology_theses/11 Wed, 22 Dec 2010 12:32:12 PST Animals must maintain stability when running over rough, uneven terrain, but the methods by which they successfully do so are largely unknown, particularly at high speeds. "Drop-down" studies are a useful way to examine how animals cope with an unexpected change in terrain height. To investigate joint function during and following a drop and make predictions about the likely preflex and reflex responses necessary to compensate for altered mechanical conditions, I ran helmeted guinea fowl Numida meleagris over a trackway with a camouflaged drop in substrate height. 2-D inverse dynamics were used to calculate the net moments, powers, and angular... ]]> Amanda Hitchcock Guineafowl--Locomotion--Case studies Predator risk cues and prey physiological state in an intertidal food web http://iris.lib.neu.edu/biology_theses/10 http://iris.lib.neu.edu/biology_theses/10 Wed, 22 Dec 2010 07:48:57 PST Non-consumptive effects exerted by predators on their prey can have far reaching implications for the structure of ecological communities and functioning of ecosystems. In addition to risk cues detected from nearby predators, physiological state of individual prey animals may influence the sign and magnitude of trait-mediated indirect interactions. Using a tri-trophic intertidal food web, I tested the influence of prey state as represented by injury history on behavior and resource allocation in an intermediate prey species, the marine snail Nucella lapillus. Despite the presence of shell injury in natural populations of this and other intertidal gastropods, injured N. lapillus showed... ]]> Timothy Robert Dwyer Ecosystem management Predatory animals--Ecology Evolution and function of the globin gene complexes of Antarctic Dragonfishes (Notothenioidei: Bathydraconidae) http://iris.lib.neu.edu/biology_theses/9 http://iris.lib.neu.edu/biology_theses/9 Tue, 16 Nov 2010 12:30:18 PST As the Southern Ocean cooled to -1.8ºC over the past 40 million years, the teleostean clade Notothenioidei became less reliant on hemoglobin and red blood cells, a trend which culminates in the white-blooded, erythrocyte-null Antarctic icefishes. The adult alpha and beta globin genes of red-blooded notothenioids are linked in 5'-to-5' orientation such that the intergenic sequences direct divergent transcription of the loci. To gain further insight into their evolution and function, we have compared the intergenic regions of the adult alpha/beta globin gene complexes from three species of Antarctic rockcods (Nototheniidae), a basal notothenioid group, and from eight species of... ]]> Joyce Yuk-Ting Lau Pterois volitans--Evolution The identification of MIG-5/dishevelled as a CACN-1 interacting protein in C. elegans, using in vivo and in vitro approaches http://iris.lib.neu.edu/biology_theses/8 http://iris.lib.neu.edu/biology_theses/8 Mon, 14 Jun 2010 09:17:12 PDT Cell migration is an important process that is essential for embryonic development and tissue and organ morphogenesis in all animals. CACN-1/Cactin is a novel and well-conserved gene that is required for distal tip cell migration and gonad morphogenesis in the C. elegans nematode worm. Previous studies have identified proteins that interact in complexes to control cell behaviors such as cell migration. In our study, we conducted a genome wide yeast two-hybrid screen to identify specific proteins that interact with CACN-1 in vivo. CACN-1 interacting proteins were first identified based on growth on auxotrophic media and were subsequently isolated, validated, and... ]]> Mouna Ibourk Cell migration--Anaylysis Symbiont-mediated protection against fungal infection in the Dampwood termite, <em>Zootermopsis Angusticollis</em> http://iris.lib.neu.edu/biology_theses/7 http://iris.lib.neu.edu/biology_theses/7 Thu, 10 Jun 2010 09:05:38 PDT Termites have a long co-evolutionary history with prokaryotic and eukaryotic gut microbes. Historically, the role of these obligate symbionts has been attributed to the nutritional welfare of the host. We hypothesize, however, that the nature of this mutualistic interaction extends beyond the nutritional benefits to the host and propose that termite gut symbionts enhance the host's defenses against pathogens. To test this hypothesis, a series of experiments were devised using the primitive dampwood termite Zootermopsis angusticollis and the entomopathogenic fungus Metarhizium anisopliae. In order to examine the role of symbionts in host protection, termites were experimentally defaunated (obligate anaerobic hindgut... ]]> Kelley Frances Schultheis Termites Entomophthoraceae Symbiosis Intrapopulational variation of Adjidaumo and Paradjidawno (Rodentia: Eomyidae) Early Oligocene, Natrona County, Wyoming http://iris.lib.neu.edu/biology_theses/6 http://iris.lib.neu.edu/biology_theses/6 Wed, 21 Apr 2010 05:24:49 PDT Intrapopulational variation was studied for 141 Adjidaumo and 33 Paradjidaumo specimens of the rodent family Eomyidae from an Early Oligocene site at the Flagstaff Rim locality, Natrona County, Wyoming. Variability of crown patterns and molar lengths and widths for each genus was examined . Results of the study revealed that mandibular and maxillary molars one and two were least variable; premolar four and molar three varied the most . Coefficients of variation for the mandibular and maxillary teeth combined ranged from 4.8 to 10 . 4 for Adjidaumo and 2.7 to 11 . 9 for Paradjidaumo. There was high degree... ]]> Deborah K. Anderson Eomyidae Rodent populations