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Life Sciences Commons

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2018

The University of Maine

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Articles 1 - 30 of 123

Full-Text Articles in Life Sciences

Eavesdropping On Gulf Of Maine Cetaceans In The Vicinity Of Mount Desert Rock, Christopher James Tremblay Dec 2018

Eavesdropping On Gulf Of Maine Cetaceans In The Vicinity Of Mount Desert Rock, Christopher James Tremblay

Electronic Theses and Dissertations

Passive acoustic monitoring, the recording and analysis of biological sound, is a standard method of research into the distribution and behavior of cetaceans worldwide. Acoustic monitoring is reliant upon a thorough reference catalog of species vocalizations and an understanding of the temporal and geographic parameters in which vocalizations occur. This study combined a standard cetacean passive acoustic monitoring survey with a concurrent visual survey at a known baleen whale summer feeding ground to determine the annual species and vocal composition, compare species detection rates using each method, and identify and attribute novel vocalizations to species. The survey took place at …


Assessing The Upper Critical Limit Of The Thermoneutral Zone In Laboratory Mice, Teumbo Ngunte Dec 2018

Assessing The Upper Critical Limit Of The Thermoneutral Zone In Laboratory Mice, Teumbo Ngunte

Electronic Theses and Dissertations

Endothermic organisms such as mammals and birds rely on high energy budgets to regulate body temperature. Many studies have previously investigated the thermo-regulation of mammals under the lower critical temperature of the thermoneutral zone, yet our knowledge in determining the upper critical limits is still scarce. As an endotherm, lab mice (Mus musculus) are perfect models to determine the cost to maintain constant body temperature as ambient temperature increases. The upper critical temperature of the thermoneutral zone of this species has been estimated to be above 32°C and below 34°C. By utilizing different genetic backgrounds of lab mice in this …


Characterization And Functional Rescue Of Congenital Muscular Dystrophy With Megaconial Myopathy In A Mouse Model Of The Disease, Ambreen A. Sayed Dec 2018

Characterization And Functional Rescue Of Congenital Muscular Dystrophy With Megaconial Myopathy In A Mouse Model Of The Disease, Ambreen A. Sayed

Electronic Theses and Dissertations

Congenital muscular dystrophy with megaconial myopathy (MDCMC) is an autosomal recessive disorder characterized by progressive muscle weakness and wasting. Megamitochondria in skeletal muscle biopsies and cognitive impairments in MDCMC patients are observations exclusive to this type of muscular dystrophy. The disease is caused by loss of function mutations in the choline kinase beta (CHKB) gene which results in dysfunction of the Kennedy pathway for the synthesis of phosphatidylcholine (PC). A rostro-caudal muscular dystrophy (rmd) mouse with a deletion in the Chkb gene resulting in MDCMC-like symptoms has been reported by our lab. In order to test if the rmd mice …


The Infection Dynamics Of Sea Lice On Atlantic Salmon (Salmo Salar) In Cobscook Bay, Maine, Usa, Catherine Anne Frederick Dec 2018

The Infection Dynamics Of Sea Lice On Atlantic Salmon (Salmo Salar) In Cobscook Bay, Maine, Usa, Catherine Anne Frederick

Electronic Theses and Dissertations

Sea lice (Lepeophtheirus and Caligus spp) are parasitic copepods that infect the external surfaces of fish hosts. Salmon lice (L. salmonis) outbreaks are commonly reported by operations in Canada, Norway, Scotland, Ireland, and the United States and are a primary concern in aquaculture because of their fish health and economic impacts. When farmed fish mortalities and treatments are accounted for, annual losses from sea louse infestations exceed $300,000,000 (Costello 2009). Farms experiencing sea lice infections risk on-site re-infection and transmission to wild populations and other farms that are hydrographically connected. In Maine, Atlantic salmon farms are located in the northeast, …


Effects Of Increasing Temperature And Acidification On The Growth And Competitive Success Of Alexandrium Catenella From The Gulf Of Maine, Drajad Seto Dec 2018

Effects Of Increasing Temperature And Acidification On The Growth And Competitive Success Of Alexandrium Catenella From The Gulf Of Maine, Drajad Seto

Electronic Theses and Dissertations

The increases in ocean temperature and pCO2 due to climate change are projected to affect the growth and future prevalence of Harmful Algal Blooms (HABs) in nearshore waters, but systematic studies on the effects these climate drivers have on harmful algal species are lacking. In particular, little is known about how future climate scenarios will affect the growth of the toxic dinoflagellate Alexandrium catenella, which produces the toxins responsible for paralytic shellfish poisoning (PSP) that threaten the health and economy of coastal communities in the Gulf of Maine. I examined growth responses of A. catenella and two other naturally co-occurring …


Developing Animal Feed Preservatives From Paper Mill Byproducts, Diana Carolina Reyes Gomez Dec 2018

Developing Animal Feed Preservatives From Paper Mill Byproducts, Diana Carolina Reyes Gomez

Electronic Theses and Dissertations

Our objectives were to evaluate the antifungal properties of technical lignins against 3 molds and 1 yeast causing hay spoilage, and for their ability to preserve alfalfa hay nutritive value. In experiment 1, 8 technical lignins and propionic acid (PRP; positive control) were tested at a dose of 40 mg/mL. The experiment had a randomized complete block design (RCBD, 4 runs) and a factorial arrangement of 3 molds × 10 additives (ADV). The effects of ADV on the yeast were also evaluated with a RCBD. Across fungi, sodium lignosulfonate (NaL) and PRP were the only treatments with a 100 ± …


Providing Experimental Evidence For Mouse Telomerase Reverse Transcriptase As A Novel And Unique Adult Neural Stem Cell Marker, Caroline Dean Curtis Dec 2018

Providing Experimental Evidence For Mouse Telomerase Reverse Transcriptase As A Novel And Unique Adult Neural Stem Cell Marker, Caroline Dean Curtis

Electronic Theses and Dissertations

With the prevalence of neurodegenerative pathologies in our society today it is imperative that we begin to look at novel approaches to the underlying problem of dying neurons that are not replaced. Adult neural stem cells exist naturally and could potentially be manipulated into targeted repair of damaged brains, given substantial research. The first step in this process is to find a way to specifically mark the earliest subset of these cells, the quiescent adult neural stem cells. Here we provide evidence for the existence of a novel and unique qANSC marker in mouse telomerase reverse transcriptase (mTERT). mTERT has …


Modeling Human Cancer Therapy Response In Patient Derived Xenografts, Joan Malcolm Dec 2018

Modeling Human Cancer Therapy Response In Patient Derived Xenografts, Joan Malcolm

Electronic Theses and Dissertations

Patient‐derived xenografts (PDXs) generated by implanting human tumor tissue into a transplant compliant mouse host have been of increasingly importance to preclinical development and have been demonstrated to have advantages compared to cancer cell lines and cell‐line xenografts (CLX) for modeling therapeutic responses in cancer. Nevertheless, many open questions remain regarding the relationship between study design factors and classification of treatment response and the molecular fidelity of tumors passaged in PDXs relative to the original patient tumor(s). The research described in this dissertation addresses both of these significant issues related to the use of PDXs as a tool for modeling …


Associations Between Avian Spruce-Fir Species, Harvest Treatments, Vegetation, And Edges, Brian W. Rolek Dec 2018

Associations Between Avian Spruce-Fir Species, Harvest Treatments, Vegetation, And Edges, Brian W. Rolek

Electronic Theses and Dissertations

Habitat loss is the primary cause of species loss and declines of global biodiversity. Several birds associated with the spruce-fir forest type (hereafter spruce-fir birds) have declining populations across the continent in the Atlantic Northern Forest, and the extent of coniferous forest has declined in some areas. This region is extensively and intensively managed for timber products.

To investigate the influence from harvest treatments on the spruce-fir bird assemblage during the breeding and post-breeding period in lowland conifer and mixed-wood forests, we used avian point count detection data to test for associations between avian assemblages and seven common harvest treatments. …


Ecological Consequences Of Personality In A Guild Of Terrestrial Small Mammals: From Trappability To Seed Dispersal, Allison M. Brehm Dec 2018

Ecological Consequences Of Personality In A Guild Of Terrestrial Small Mammals: From Trappability To Seed Dispersal, Allison M. Brehm

Electronic Theses and Dissertations

Individual animals exhibit consistent behavioral tendencies over time and across contexts that have been termed personalities. Personality encapsulates an individual’s unique way of behaving and responding to life’s challenges, and since individuals vary in both personality type and their ability to exhibit behavioural plasticity, there are important links between an individual’s personality and its response to a changing environment; resulting in the study of animal personalities becoming increasingly popular in recent years. Previous research suggests that personality traits measured through standardized behavioural tests predict trappability (i.e. ‘trap happiness’ versus ‘trap shyness’). This relationship has been explored only within single …


Multi-Tactic Ecological Weed Management In A Changing Climate, Sonja K. Birthisel Dec 2018

Multi-Tactic Ecological Weed Management In A Changing Climate, Sonja K. Birthisel

Electronic Theses and Dissertations

Climate change is expected to impact weed communities in Maine, and the efficacy of tools and tactics farmers use to manage them. Through seedbank sampling and surveys of Maine organic farms, we identified currently rare weeds that are known to be especially abundant or problematic in warmer areas of the USA and might therefore represent an emerging agronomic risk. Many ecological weed management strategies that focus on depleting the weed seedbank are expected to remain effective in a changing climate, and become increasingly important as efficacy of cultivation and some herbicide applications diminish or become more variable. Through field experiments, …


Climatic Range Filling Of North American Trees, Benjamin Seliger Dec 2018

Climatic Range Filling Of North American Trees, Benjamin Seliger

Electronic Theses and Dissertations

Understanding the degree to which species distributions are controlled by climate is crucial for forecasting biodiversity responses to climate change. Climatic equilibrium, when species are found in all places which are climatically suitable, is a fundamental assumption of species distribution models, but there is evidence in support of climate disequilibria in species ranges. Long-lived, sessile organisms such as trees may be especially vulnerable to being outpaced by climate change, and thus prone to disequilibrium. In this dissertation, I tested the degree to which North American trees are in equilibrium with their potential climatic ranges using the ‘range filling’ metric, which …


Black Soldier Fly Larvae As Value-Added Feed For Aquaculture In Maine, Joshua Villazana Dec 2018

Black Soldier Fly Larvae As Value-Added Feed For Aquaculture In Maine, Joshua Villazana

Electronic Theses and Dissertations

Black soldier flies (BSF), Hermetia illucens (Linnaeus) (Diptera: Stratiomyidae) consume decaying organic waste as larvae (BSFL) and can be used for recycling a variety of biogenic wastes. BSFL can also be processed into value-added animal feeds, including those used in aquaculture. An overarching goal of this project was to obtain additional insights into BSF biology to improve their rearing and handling in future mass-production facilities serving Maine aquaculture.

We tested BSFL growth in the laboratory on seven seafood wastes from Maine fish processing facilities. Substrates potentially suitable for BSFL rearing included finfish trimmings, wet sea cucumber, dry quahog, and sea …


Minerva 2018, The Honors College Dec 2018

Minerva 2018, The Honors College

Minerva

This issue of Minerva includes an article on the Honors Endeavor by recently retired faculty member, David Gross; an adaptation of Isaac Record's 2018 Distinguished Honors Graduate lecture; an article on 2018 Honors Read Just Mercy; and a wonderful farewell to beloved Honors College Administrative Specialist, Deb Small. Other highlights include a reflection by CLAS-Honors preceptor of philosophy, Hao Hong; and a look into 2018-2019 student thesis research.


Landings, Vol. 26, No. 12, Maine Lobstermen’S Community Alliance Dec 2018

Landings, Vol. 26, No. 12, Maine Lobstermen’S Community Alliance

Landings: News & Views from Maine's Lobstering Community

Landings content emphasizes science, history, resource sustainability, economic development, and human interest stories related to

Maine’s lobster industry. The newsletter emphasizes lobstering as a traditional, majority-European American lifeway with an economic and social heritage unique to the coast of Maine. The publication focuses how ongoing research to engage in sustainable, non-harmful, and non-wasteful commercial fishing practices benefit both the fishery and Maine's coastal legacy.

Maine Lobstermen’s Community Alliance (MLCA) started publication of Landings, a 24-page newsletter in January 2013 as the successor of the Maine Lobstermen’s Association (MLA) Newsletter. As of 2022, the MLCA published over 6,500 copies of …


The Effects Of Seasonal Variations In Chemistry And Hydrology On The Microbial Community And Its Sulfide Oxidation Potential In A Naturally Acidic Maine Stream, Raymond C. Kahler Iii Dec 2018

The Effects Of Seasonal Variations In Chemistry And Hydrology On The Microbial Community And Its Sulfide Oxidation Potential In A Naturally Acidic Maine Stream, Raymond C. Kahler Iii

Electronic Theses and Dissertations

Sulfide minerals oxidize through interaction with water and oxygen, releasing hydrogen ions. The process often occurs naturally near metal sulfide deposits, and can be accelerated through mining. Microorganisms accelerate the rate of sulfide oxidation. Acidified streams typically contain high metal concentrations (e.g. aluminum) and microbes in these systems may develop resistances to metal toxicity. Stream flow can affect sulfide oxidation and microbial community structure. Baseflow can influence stream chemistry from interactions with the surrounding bedrock, while stormflow affects stream chemistry and the local microbial community through dilution and addition of microbes transported by runoff. Microbial community composition is affected by …


Host Mediated Mechanisms Of Fungal Cell Spread In A Transparent Zebrafish Infection Model, Allison Scherer Dec 2018

Host Mediated Mechanisms Of Fungal Cell Spread In A Transparent Zebrafish Infection Model, Allison Scherer

Electronic Theses and Dissertations

Innate immunity has developed elegant processes for the detection and clearance of invasive fungal pathogens. Disseminated candidiasis is of significant concern for those with suppressed immune systems or indwelling medical equipment, and mortality in these groups approaches 70%. Poor patient outcomes have spurred the need to understand how this non-motile pathogen spreads in the host. Technical limitations have previously hindered our ability to visualize the role of innate immunity and host tissue barriers in the spread of C. albicans in vivo. Using the zebrafish model to overcome these limitations, we have examined three potential host-mediated mechanisms of dissemination: movement …


Lead Poisoning In Maine's Common Loons: Examining Biological And Social Dimensions, Brooke S. Macdonald Dec 2018

Lead Poisoning In Maine's Common Loons: Examining Biological And Social Dimensions, Brooke S. Macdonald

Electronic Theses and Dissertations

Lead poisoning from ingested fishing tackle is a well-documented conservation concern for adult common loons in the Northeastern United States. To mitigate this issue, the state of Maine began implementing restrictions on lead tackle use in 2002, with new legislation added in 2016 and 2017. In addition to legislative action there have been various non-regulatory strategies employed in Maine to help raise awareness, such as the Fish Lead Free campaign. Human behavior is the root cause of lead fishing tackle in aquatic environments, and also can determine the success of legislative and educational efforts. Measuring underlying factors that influence behaviors, …


Thermal And Microbial Effects On Brown Macroalgae: Heat Acclimation And The Biodiversity Of The Microbiome, Charlotte Tc Quigley Nov 2018

Thermal And Microbial Effects On Brown Macroalgae: Heat Acclimation And The Biodiversity Of The Microbiome, Charlotte Tc Quigley

Electronic Theses and Dissertations

This dissertation examines effects of stress on brown algal biology from a macroscopic scale by examining the whole aquaculture crops, and at a microscopic level by examining the macroalgal microbiome, across the vertical stress gradient of the intertidal zone and across the latitudes of their biogeographic ranges. Thermal stress negatively affected seedstock gametophytes of the kelp Alaria esculenta isolated from northern and southern locations in Maine. However, previous thermal stress had a positive effect on growth of the next-generation sporophytes. Alaria esculenta has potential as a kelp crop in Maine’s sea vegetable aquaculture sector and implementing this protocol may allow …


Landings, Vol. 26, No. 11, Maine Lobstermen’S Community Alliance Nov 2018

Landings, Vol. 26, No. 11, Maine Lobstermen’S Community Alliance

Landings: News & Views from Maine's Lobstering Community

Landings content emphasizes science, history, resource sustainability, economic development, and human interest stories related to

Maine’s lobster industry. The newsletter emphasizes lobstering as a traditional, majority-European American lifeway with an economic and social heritage unique to the coast of Maine. The publication focuses how ongoing research to engage in sustainable, non-harmful, and non-wasteful commercial fishing practices benefit both the fishery and Maine's coastal legacy.

Maine Lobstermen’s Community Alliance (MLCA) started publication of Landings, a 24-page newsletter in January 2013 as the successor of the Maine Lobstermen’s Association (MLA) Newsletter. As of 2022, the MLCA published over 6,500 copies of …


Emergent Sustainability In Open Property Regimes, Mark Moritz, Roy Behnke, Christine M. Beitl, Rebecca Bliege Bird, Rafael Chiaravalloti, Julia Clark, Stefani Crabtree, Sean S. Downy, Ian M. Hamilton, Sui Chian Phang, Paul Scholte, Jim Wilson Nov 2018

Emergent Sustainability In Open Property Regimes, Mark Moritz, Roy Behnke, Christine M. Beitl, Rebecca Bliege Bird, Rafael Chiaravalloti, Julia Clark, Stefani Crabtree, Sean S. Downy, Ian M. Hamilton, Sui Chian Phang, Paul Scholte, Jim Wilson

Anthropology Faculty Scholarship

Current theoretical models of the commons assert that common-pool resources can only be managed sustainably with clearly defined boundaries around both communities and the resources that they use. In these theoretical models, open access inevitably leads to a tragedy of the commons. However, in many open-access systems, use of common-pool resources seems to be sustainable over the long term (i.e., current resource use does not threaten use of common-pool resources for future generations). Here, we outline the conditions that support sustainable resource use in open property regimes. We use the conceptual framework of complex adaptive systems to explain how processes …


Dorothy J. Jackson Fres Fls, Scottish Entomologist: A Bibliography, Jack R. Mclachlan Oct 2018

Dorothy J. Jackson Fres Fls, Scottish Entomologist: A Bibliography, Jack R. Mclachlan

Biology and Ecology Faculty Scholarship

Dorothy Jean Jackson FRES FLS (1892-1973) should be familiar to anyone interested in water beetles. She published prolifically on the ecology, distribution, flight capacity, and parasites of water beetles, and made especially important contributions to our knowledge of dytiscids. Here I provide a more extensive bibliography of her work that is almost certainly incomplete, but I think includes most of her scientific output between 1907 and 1973. Her first paper was published when she was 14 years old, and her last was completed by Jack Balfour-Browne and published posthumously.


Landings, Vol. 26, No. 10, Maine Lobstermen’S Community Alliance Oct 2018

Landings, Vol. 26, No. 10, Maine Lobstermen’S Community Alliance

Landings: News & Views from Maine's Lobstering Community

Landings content emphasizes science, history, resource sustainability, economic development, and human interest stories related to

Maine’s lobster industry. The newsletter emphasizes lobstering as a traditional, majority-European American lifeway with an economic and social heritage unique to the coast of Maine. The publication focuses how ongoing research to engage in sustainable, non-harmful, and non-wasteful commercial fishing practices benefit both the fishery and Maine's coastal legacy.

Maine Lobstermen’s Community Alliance (MLCA) started publication of Landings, a 24-page newsletter in January 2013 as the successor of the Maine Lobstermen’s Association (MLA) Newsletter. As of 2022, the MLCA published over 6,500 copies of …


The Dandy Scroll, Fall 2018, University Of Maine Pulp And Paper Foundation Oct 2018

The Dandy Scroll, Fall 2018, University Of Maine Pulp And Paper Foundation

General University of Maine Publications

The Fall 2018 issue of The Dandy Scroll newsletter produced by the University of Maine Pulp and Paper Foundation.


The Effect Of Wild Blueberry Bioactives On Endothelial Cell Migration And Angiogenesis: An In Vitro Mechanistic, Genomic And Proteomic Approach, Panagiotis Tsakiroglou Sep 2018

The Effect Of Wild Blueberry Bioactives On Endothelial Cell Migration And Angiogenesis: An In Vitro Mechanistic, Genomic And Proteomic Approach, Panagiotis Tsakiroglou

Electronic Theses and Dissertations

The goal of this study is to investigate the effects of wild blueberry fractions (Anthocyanins and Phenolic acids) on vascular function and physiology. More specifically the potential effects of the above fractions and their combination in physiological concentrations on endothelial cell migration, angiogenesis, gene expression and proteins synthesis of markers related to the above processes. The objectives are to study whether anthocyanins, phenolic acids and their combinations (ACNs:PAs) affect: a) cell proliferation, b) speed of endothelial cell migration, c) angiogenesis, d) gene expression of genes critical for cell migration and angiogenesis such as RAC1, RHOA, AKT1, eNOS and VEGF and …


Landings, Vol. 26, No. 9, Maine Lobstermen’S Community Alliance Sep 2018

Landings, Vol. 26, No. 9, Maine Lobstermen’S Community Alliance

Landings: News & Views from Maine's Lobstering Community

Landings content emphasizes science, history, resource sustainability, economic development, and human interest stories related to

Maine’s lobster industry. The newsletter emphasizes lobstering as a traditional, majority-European American lifeway with an economic and social heritage unique to the coast of Maine. The publication focuses how ongoing research to engage in sustainable, non-harmful, and non-wasteful commercial fishing practices benefit both the fishery and Maine's coastal legacy.

Maine Lobstermen’s Community Alliance (MLCA) started publication of Landings, a 24-page newsletter in January 2013 as the successor of the Maine Lobstermen’s Association (MLA) Newsletter. As of 2022, the MLCA published over 6,500 copies of …


Periodic Evaluation Of Northeastern Spruce And Balsam Fir Lumber Properties, Ben L. Farber Aug 2018

Periodic Evaluation Of Northeastern Spruce And Balsam Fir Lumber Properties, Ben L. Farber

Electronic Theses and Dissertations

PERIODIC EVALUATION OF NORTHEASTERN SPRUCE AND BALSAM FIR LUMBER PROPERTIES

By Benjamin Farber

Advisors: Dr. Douglas Gardner

An Abstract of the Thesis Presented

In Partial Fulfilment of the Requirements for the

Degree of Master of Science

(In Forest Resources)

August 2018

In the past two decades, proportions of juvenile wood have increased in lumber cut from intensively managed Southern yellow pine (Pinus spp.) plantation-based forests. Knowing that a decrease in rotation age can increase proportions of juvenile wood, which in turn negatively affects mechanical properties in lumber, the SYP grouping was evaluated to determine if the published design values …


Characterization Of Phosphorylated G Protein Function And Membrane Culstering By Super Resolution Imaging, Sarah A. Alamer Aug 2018

Characterization Of Phosphorylated G Protein Function And Membrane Culstering By Super Resolution Imaging, Sarah A. Alamer

Electronic Theses and Dissertations

Heterotrimeric G proteins play crucial roles in various signal transduction pathways, where they act as molecular switches in transducing a signal from G protein coupled receptors (GPCRs) at the plasma membrane to downstream effectors. Although their mechanism of action is mostly concentrated at the plasma membrane, their dynamic membrane organization and how it is regulated are not understood. Due to the diffraction limited resolution of fluorescence microscopy, studying the precise organization of membrane proteins can be challenging. In this study, we took advantage of super-resolution fluorescence photoactivation localization microscopy (FPALM) to overcome this challenge. Dictyostelium discoideum was used as a …


Drivers Of Tree Growth And Mortality In An Uneven-Aged, Mixed-Species Conifer Forest Of Northeastern United States, Erin Fien Aug 2018

Drivers Of Tree Growth And Mortality In An Uneven-Aged, Mixed-Species Conifer Forest Of Northeastern United States, Erin Fien

Electronic Theses and Dissertations

Individual tree growth and mortality drive forest stand dynamics and are important, universal metrics of tree success. Studying the factors that affect growth and mortality is particularly challenging in mixed-species, uneven-aged systems due to their defining heterogeneity and strong temporal and spatial variability. However a better understanding of the factors driving growth and mortality in mixed-species, uneven-aged forest is crucial to managing and maintaining these valuable systems for the future.

The goal of this study was to determine the relative importance of individual tree attributes (e.g., species, size, neighborhood crowding, crown position) and environmental characteristics (e.g., soil moisture) in driving …


Molecular Mechanisms Underlying Toxicant Effects On Mast Cell Signaling And Mitochondria, Juyoung Katherine Shim Aug 2018

Molecular Mechanisms Underlying Toxicant Effects On Mast Cell Signaling And Mitochondria, Juyoung Katherine Shim

Electronic Theses and Dissertations

Mast cells contribute to numerous physiological processes and diseases including immunological and neurological roles. Mast cells degranulate, releasing potent mediators, following signaling transduction initiated by receptor crosslinking. Previously, we showed that the environmental toxicant arsenic and the antibacterial agent triclosan inhibit mast cell degranulation; thus, we have investigated the mechanisms underlying their inhibitory action. We have discovered that arsenic targets early steps in the mast cell signaling pathway: it inhibits phosphorylation of early tyrosine kinase Syk and of Syk’s direct substrate PI3K. Arsenic’s tyrosine phosphorylation inhibition causes inhibition of calcium influx into the cytosol, a key event necessary for degranulation. …