Life Sciences Commons^™

Actaea Racemosa: The Slender Wands Of Flowering Common Black Cohosh Beckon Us To Explore Woodlands, W. John Hayden

Biology Faculty Publications

Common Black Cohosh is a perennial rhizomatous forest herb. Its horizontal rhizomes bear numerous adventitious roots on the underside and aerial stems of annual duration on the upper side, along with knobby scars left from aerial stems of previous years. Leaves are alternate, twice or thrice compound in ternate or pinnate patterns, and large—up to 1 m long. Individual leaflet size and shape vary with position in the large compound leaves, with position of a leaf on the stem, and from population to population. Most often leaflets are coarsely serrate, lobed to deeply incised, with a truncate to cuneate base …

Stretch Activated Channels In Proprioceptive Organs Of Crab And Crayfish Are Sensitive To Gadolinium But Not Amiloride, Ruthenium Red Or Low Ph, Viresh Dayaram, Cole A. Malloy, Sarah Martha, Brenda Alvarez, Ikenna Chukwudolue, Nadera Dabbain, Dlovan D.Mahmood, Slavina Goleva, Tori Hickey, Angel Ho, Molly King, Paige Kington, Matthew Mattingly, Samuel Potter, Landon Simpson, Amanda Spence, Henry Uradu, Jacob Van Doorn, Robin L. Cooper

Biology Faculty Publications

The type of stretch activated receptors (SARs) in the chordotonal organs in the crab walking leg and of the muscle receptor organ (MRO) in the crayfish abdomen have not yet been classified as to their molecular or pharmacological profile. The purpose of this study is to examine the pharmacological profile of SARs in the proprioceptive neurons in the crab and crayfish models. Since many SARs share the pharmacological profile of displaying low pH or being proton sensitive (i.e. being more active) or blocked by the diuretic amiloride or ruthenium red as well as being blocked by the broad stretch activated …

Detection Of Intestinal Pathogens In River, Shore, And Drinking Water In Lima, Peru, David Grothen, Sydney J. Zach, Paul H. Davis

Biology Faculty Publications

Water quality management is an ongoing struggle for many locations worldwide. Current testing of water supplies can be time-consuming, expensive, and lack sensitivity. This study describes an alternative, easy-to-use, and inexpensive method to water sampling and testing at remote locations. This method was employed to detect a number of intestinal pathogens in various locations of Lima, Peru. A total of 34 PCR primer pairs were tested for specificity and high-yield amplification for 12 different pathogens using known DNA templates. Select primers for each pathogen were then tested for minimum detection limits of DNA. Water samples were collected from 22 locations. …

Predicting Hiv Pre-Exposure Prophylaxis Efficacy For Women Using A Preclinical Pharmacokinetic-Pharmacodynamic In Vivo Model, Angela Wahl, Phong T. Ho, Paul W. Denton, Katy L. Garrett, Michael G. Hudgens, Glenn Swartz, Cynthia O'Neill, Fulvia Veronese, Angela D. Kashuba, J. Victor Garcia

Biology Faculty Publications

The efficacy of HIV pre-exposure prophylaxis (PrEP) relies on adherence and may also depend on the route of HIV acquisition. Clinical studies of systemic tenofovir disoproxil fumarate (TDF) PrEP revealed reduced efficacy in women compared to men with similar degrees of adherence. To select the most effective PrEP strategies, preclinical studies are critically needed to establish correlations between drug concentrations (pharmacokinetics [PK]) and protective efficacy (pharmacodynamics [PD]). We utilized an in vivo preclinical model to perform a PK-PD analysis of systemic TDF PrEP for vaginal HIV acquisition. TDF PrEP prevented vaginal HIV acquisition in a dose-dependent manner. PK-PD modeling of …

Planaria: An Animal Model That Integrates Development, Regeneration And Pharmacology, Oné R. Pagán

Biology Faculty Publications

Although planarians are established model organisms in developmental biology and regeneration studies, in the last forty years or so, they have caught the attention of pharmacologists, especially to study the pharmacology of drugs of abuse. This review covers the following topics: some fundamentals of the history of animal models and planarians in biomedical research; an abbreviated story of systematic pharmacology research using planarians as a model organism; an example of how planarians are contributing to the search for compounds against acute cocaine toxicity; an analysis of the number of papers on planarians and pharmacological topics from 1900- 2016; some perspectives …

How Do Former Undergraduate Mentors Evaluate Their Mentoring Experience 3-Years Post-Mentoring: A Phenomenological Study, Kari L. Nelson, Christine E. Cutucache

Biology Faculty Publications

This phenomenological study involves a unique, longitudinal assessment of the lived experiences of former undergraduate mentors (n=7) in light of their current experiences (i.e., career or advanced schooling). The objective of a phenomenological study is to engage in in-depth probing of a representative number of participants. Specifically, we followed up with graduates of the Nebraska STEM 4U (NE STEM 4U) intervention 3 years post-program, with the overall goal of describing the mentors’ experiences using the lens of their current experiences. This type of longitudinal perspective of mentoring is greatly lacking in the current literature. At the time of the interviews, …

Complete Genome Sequences Of Cluster A Mycobacteriophages Bobswaget, Fred313, Kady, Lokk, Myradee, Stagni, And Stepmih, Kristen A. Butela, Susan M. R. Gurney, Heather L. Hendrickson, Janine M. Leblanc-Straceski, Anastasia M. Zimmerman, Stephanie B. Conant, Nikki E. Freed, Olin K. Silander, Joshua J. Thomson, Charlotte A. Berkes, Cristina Bertolez, Courtney G. Davies, Amber Elinsky, Alison J. Hanlon, Juliette Nersesyan, Payal Patel, John Sherwood, Tiffany Tieu Ngo, Kathryn A. Wisniewski, Kathrine Yacoo, Paul M. Arendse, Nathan W. Bowlen, Jasmina Cunmulaj, Julie L. Downs, Charlee A. Ferrenberg, Alexandra E. Gassman, Cody E. R. Gilligan, Emily Gorkiewicz, Christopher Harness, Anthony Huffman, Christina Jones, Anna Julien, Alexis E. Kupic, Sayonara F. Latu, Thomas J. Manning, Danielle Maxwell, Merrimack College Sea-Phages Annotators 2016, Catherine E. Meyer, Madeleine Reardon, Matthew Slaughter, Royce Swasey, Rebecca I. Tennent, Victoria Torres, Tamia Waller, Rachel M. Worcester, Brooke L. Yost, Steven G. Cresawn, Rebecca A. Garlena, Deborah Jacobs-Sera, Welkin H. Pope, Daniel A. Russell, Graham F. Hatfull, Jacob D. Kagey

Biology Faculty Publications

Seven mycobacteriophages from distinct geographical locations were isolated, using Mycobacterium smegmatis mc2155 as the host, and then purified and sequenced. All of the genomes are related to cluster A mycobacteriophages, BobSwaget and Lokk in subcluster A2; Fred313, KADY, Stagni, and StepMih in subcluster A3; and MyraDee in subcluster A18, the first phage to be assigned to that subcluster.

An Undergraduate Cell Biology Lab: Western Blotting To Detect Proteins From Drosophila Eye, Neha Gogia, Ankita Sarkar, Amit Singh

Biology Faculty Publications

We have developed an undergraduate laboratory to allow detection and localization of proteins in the compound eye of Drosophila melanogaster, a.k.a fruit fly. This lab was a part of the undergraduate curriculum of the cell biology laboratory course aimed to demonstrate the use of Western Blotting technique to study protein localization in the adult eye of Drosophila. Western blotting, a two-day laboratory exercise, can be used to detect the presence of proteins of interests from total protein isolated from a tissue. The first day involves isolation of proteins from the tissue and SDS-PAGE (sodium dodecyl sulfate-polyacrylamide) gel …

Real-Time Quantitative Pcr To Demonstrate Gene Expression In An Undergraduate Lab, Abijeet Singh Mehta, Amit Singh

Biology Faculty Publications

The objective of this teaching note is to develop a laboratory exercise, which allows students to get a hands-on experience of a molecular biology technique to analyze gene expression. The short duration of the biology laboratory for an undergraduate curriculum is the biggest challenge with the development of new labs. An important part of cell biology or molecular biology undergraduate curriculum is to study gene expression. There are many labs to study gene expression in qualitative manner. The commonly used reporter gene expression studies are primarily qualitative. However, there is no hands-on experience exercise to quantitatively determine gene expression. Therefore, …

Increased Bufflehead (Bucephala Albeola) Breeding Activity In Minnesota, Susan N. Ellis-Felege, Cassandra G. Skaggs, Gregory A. Knutsen

Biology Faculty Publications

Buffleheads (Bucephala albeola) predominantly nest in the boreal forests and aspen parklands of Canada and Alaska. Historically, Buffleheads were common migrants but not summer residents in Minnesota. However, recent observations in Minnesota and surrounding states suggest increased breeding activity in the region. In 1978, the first Bufflehead brood in Minnesota was recorded at East Park Wildlife Management Area. Annually, Agassiz National Wildlife Refuge (NWR) has conducted pair and brood surveys, with species-specific records available from 1990 to 2014. We report an increase in numbers of Bufflehead breeding pairs and broods at Agassiz NWR and new pair observations in …

Landscape Features Affecting Northern Bobwhite Predator-Specific Nest Failures In Southeastern Usa, Susan N. Ellis-Felege, Shannon E. Albeke, Nathan P. Nibbelink, Michael J. Conroy, Clay Sisson, William E. Palmer, John P. Carroll

Biology Faculty Publications

Nest predation is a critical component in avian productivity and typically is the leading cause of nest failure for most birds. Several landscape features are thought to drive the behavioral interaction between northern bobwhite (Colinus virginianus; e.g., nest placement) and their predators (e.g., search methods for food acquisition). In order to understand habitat characteristics influencing predation, we studied bobwhite nests using 24-hour near-infrared video cameras. We monitored 675 bobwhite nests with cameras on 3 properties in northern Florida and southern Georgia, USA, during 2000–2006. To test the association between nest failures and specific failure causes with landscape structure, we calculated …

Identification Of Rifampicin Resistance Mutations In Escherichia Coli, Including An Unusual Deletion Mutation, Eugene Y. Wu, Angela K. Hilliker

Biology Faculty Publications

Rifampicin is an effective antibiotic against mycobacterial and other bacterial infections, but resistance readily emerges in laboratory and clinical settings. We screened Escherichia coli for rifampicin resistance and identified numerous mutations to the gene encoding the β chain of RNA polymerase (rpoB), including an unusual nine nucleotide deletion mutation. Structural modeling of the deletion mutant indicates locations of potential steric clashes with rifampicin. Sequence conservation in the region near the deletion mutation suggests a similar mutation may also confer resistance during the treatment of tuberculosis.

A Computational Study Of Vegf Production By Patterned Retinal Epithelial Cell Colonies As A Model For Neovascular Macular Degeneration, Qanita Bani Baker, Gregory J. Podgorski, Elizabeth Vargis, Nicholas Flann

Biology Faculty Publications

Background: The configuration of necrotic areas within the retinal pigmented epithelium is an important element in the progression of age-related macular degeneration (AMD). In the exudative (wet) and non-exudative (dry) forms of the disease, retinal pigment epithelial (RPE) cells respond to adjacent atrophied regions by secreting vascular endothelial growth factor (VEGF) that in turn recruits new blood vessels which lead to a further reduction in retinal function and vision. In vitro models exist for studying VEGF expression in wet AMD (Vargis et al., Biomaterials 35(13):3999–4004, 2014), but are limited in the patterns of necrotic and intact RPE epithelium they can …

Human Cytomegalovirus Interleukin-10 Enhances Matrigel Invasion Of Mda-Mb-231 Breast Cancer Cells, Cendy Valle Oseguera, Juliet Spencer

Biology Faculty Publications

Background: While some risk factors for breast cancer are well-known, the influence of other factors, particularly virus infection, remains unclear. Human cytomegalovirus (HCMV) is widespread in the general population, and both molecular and epidemiological evidence has indicated links between HCMV and breast cancer. The HCMV protein cmvIL-10 is a potent suppressor of immune function that has also been shown to promote proliferation and migration of breast cancer cells. In this study, the impact of cmvIL-10 on tumor cell invasion through a simulated basement membrane was investigated.

Results: MDA-MB-231 breast cancer cells exhibited invasion through a matrigel layer that was significantly …

Dynamic Acquisition And Loss Of Dual-Obligate Symbionts In The Plant-Sap-Feeding Adelgidae (Hemiptera: Sternorrhyncha: Aphidoidea), Carol D. Von Dohlen, Usha Spaulding, Kistie B. Patch, Ethan P. White, Robert G. Foottit, Nathan P. Havill, Gaelen R. Burke

Biology Faculty Publications

Sap-sucking insects typically engage in obligate relationships with symbiotic bacteria that play nutritional roles in synthesizing nutrients unavailable or in scarce supply from the plant-sap diets of their hosts. Adelgids are sap-sucking insects with complex life cycles that involve alternation between conifer tree species. While all adelgid species feed on spruce during the sexual phase of their life cycle, each adelgid species belongs to a major lineage that feeds on a distinct genus of conifers as their alternate host. Previous work on adelgid symbionts had discovered pairs of symbionts within each host species, and unusual diversity across the insect family, …

Cullin-4 Regulates Wingless And Jnk Signaling-Mediated Cell Death In The Drosophila Eye., Meghana Tare, Ankita Sarkar, Shimpi Bedi, Madhuri Kango-Singh, Amit Singh

Biology Faculty Publications

In all multicellular organisms, the fundamental processes of cell proliferation and cell death are crucial for growth regulation during organogenesis. Strict regulation of cell death is important to maintain tissue homeostasis by affecting processes like regulation of cell number, and elimination of unwanted/unfit cells. The developing Drosophila eye is a versatile model to study patterning and growth, where complex signaling pathways regulate growth and cell survival. However, the molecular mechanisms underlying regulation of these processes is not fully understood. In a gain-of-function screen, we found that misexpression of cullin-4 (cul-4), an ubiquitin ligase, can rescue reduced eye mutant phenotypes. Previously, …

Murine Models Of Splenic Marginal Zone Lymphoma: A Role For Cav1?, Chelsey L. Patten, Christine E. Cutucache

Biology Faculty Publications

Dozens of murine models of indolent and aggressive B-cell lymphomas have been generated to-date. These include those manifesting chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL) as well as xenografts of mantle cell lymphoma (MCL). These models have led to an improved understanding of disease etiology, B-cell biology, immunomodulation, and the importance of the tumor microenvironment. Despite these efforts in CLL, DLBCL, and MCL, considerably little progress toward a model of splenic marginal zone lymphoma (SMZL) has been accomplished. Herein, we describe the similarities and differences between CLL, MCL, and SMZL, and highlight effective murine models that mimic disease …

Animating And Exploring Phylogenies With Fibre Plots, William D. Pearse

Biology Faculty Publications

Despite the progress that has been made in many other aspects of data visualisation, phylogenies are still represented in much the same way as they first were by Darwin. In this brief essay, I give a short review of what I consider to be some recent major advances, and outline a new kind of phylogenetic visualisation. This new graphic, the fibre plot, uses the metaphor of sections through a tree to describe change in a phylogeny. I suggest it is a useful tool in gaining an rapid overview of the timing and scale of diversification in large phylogenies.

Photography-Based Taxonomy Is Inadequate, Unnecessary, And Potentially Harmful For Biological Sciences, Luis M P Ceríaco, Eliécer E. Gutiérrez, Alain Dubois, Hendrik Freitag, 537 Co-Authors

Biology Faculty Publications

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per …

Importance Of Heat And Pressure For Solubilization Of Recombinant Spider Silk Proteins In Aqueous Solution, Justin A. Jones, Thomas I. Harris, Paula F. Oliveira, Brianne E. Bell, Abdulrahman Alhabib, Randolph V. Lewis

Biology Faculty Publications

The production of recombinant spider silk proteins continues to be a key area of interest for a number of research groups. Several key obstacles exist in their production as well as in their formulation into useable products. The original reported method to solubilize recombinant spider silk proteins (rSSp) in an aqueous solution involved using microwaves to quickly generate heat and pressure inside of a sealed vial containing rSSp and water. Fibers produced from this system are remarkable in their mechanical ability and demonstrate the ability to be stretched and recover 100 times. The microwave method dissolves the rSSPs with dissolution …

Photography-Based Taxonomy Is Inadequate, Unnecessary, And Potentially Harmful For Biological Sciences, Luis M. P. Ceríaco, Eliécer E. Gutiérrez, Alain Dubois, Rafael O. De Sá, Et Al.

Biology Faculty Publications

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per …

Assessment Of Olfactory Function In Maptassociated Neurodegenerative Disease Reveals Odor-Identification Irreproducibility As A Non-Disease-Specific, General Characteristic Of Olfactory Dysfunction, Katerina Markopoulou, Bruce A. Chase, Piotr Robowski, Audrey Strongosky, Ewa Narożańska, Emilia J. Sitek, Mariusz Berdynski, Maria Barcikowska, Matt C. Baker, Jarosøaw Søawek, Christine Klein, Katja Hückelheim, Meike Kasten, Zbigniew K. Wszolek

Biology Faculty Publications

Olfactory dysfunction is associated with normal aging, multiple neurodegenerative disorders, including Parkinson’s disease, Lewy body disease and Alzheimer’s disease, and other diseases such as diabetes, sleep apnea and the autoimmune disease myasthenia gravis. The wide spectrum of neurodegenerative disorders associated with olfactory dysfunction suggests different, potentially overlapping, underlying pathophysiologies. Studying olfactory dysfunction in presymptomatic carriers of mutations known to cause familial parkinsonism provides unique opportunities to understand the role of genetic factors, delineate the salient characteristics of the onset of olfactory dysfunction, and understand when it starts relative to motor and cognitive symptoms. We evaluated olfactory dysfunction in 28 carriers …

Hydrodynamic Properties Of Fin Whale Flippers Predict Maximum Rolling Performance, Paolo S. Segre, David E. Cade, Frank E. Fish, Jean Potvin, Ann N. Allen, John Calambokidis, Ari S. Friedlaender, Jeremy A. Goldbogen

Biology Faculty Publications

Maneuverability is one of the most important and least understood aspects of animal locomotion. The hydrofoil-like flippers of cetaceans are thought to function as control surfaces that effect maneuvers, but quantitative tests of this hypothesis have been lacking. Here, we constructed a simple hydrodynamic model to predict the longitudinal-axis roll performance of fin whales, and we tested its predictions against kinematic data recorded by on-board movement sensors from 27 free-swimming fin whales. We found that for a given swimming speed and roll excursion, the roll velocity of fin whales calculated from our field data agrees well with that predicted by …

Transcriptomic Comparison Of Invasive Bigheaded Carps (Hypophthalmichthys Nobilis And Hypophthalmichthys Molitrix) And Their Hybrids, Jun Wang, James T. Lamer, Sarah Gaughan, Michael Wachholtz, Chenghui Wang, Guoquing Lu

Biology Faculty Publications

Bighead carp (Hypophthalmichthys nobilis) and silver carp (Hypophthalmichthys molitrix), collectively called bigheaded carps, are invasive species in the Mississippi River Basin (MRB). Interspecific hybridization between bigheaded carps has been considered rare within their native rivers in China; however, it is prevalent in the MRB. We conducted de novo transcriptome analysis of pure and hybrid bigheaded carps and obtained 40,759 to 51,706 transcripts for pure, F1 hybrid, and backcross bigheaded carps. The search against protein databases resulted in 20,336–28,133 annotated transcripts (over 50% of the transcriptome) with over 13,000 transcripts mapped to 23 Gene Ontology biological processes and 127 KEGG metabolic …

Better Late Than Never: Effective Air-Borne Hearing Of Toads Delayed By Late Maturation Of The Tympanic Middle Ear Structures, Molly C. Womack, Jakob Christensen-Dalsgaard, Kim L. Hoke

Biology Faculty Publications

Most vertebrates have evolved a tympanic middle ear that enables effective hearing of airborne sound on land. Although inner ears develop during the tadpole stages of toads, tympanic middle ear structures are not complete until months after metamorphosis, potentially limiting the sensitivity of post-metamorphic juveniles to sounds in their environment. We tested the hearing of five species of toads to determine how delayed ear development impairs airborne auditory sensitivity. We performed auditory brainstem recordings to test the hearing of the toads and used micro-computed tomography and histology to relate the development of ear structures to hearing ability. We found a …

Cotinine Antagonizes The Behavioral Effects Of Nicotine Exposure In The Planarian Girardia Tigrina, Daniel J. Bach, Matthew Tenaglia, Debra L. Baker, Sean Deats, Erica Montgomery, Oné R. Pagán

Biology Faculty Publications

Nicotine is one of the most addictive drugs abused by humans. Our laboratory and others have demonstrated that nicotine decreases motility and induces seizure-like behavior in planarians (pSLM, which are vigorous writhing and bending of the body) in a concentration-dependent manner. Nicotine also induces withdrawal-like behaviors in these worms. Cotinine is the major nicotine metabolite in humans, although it is not the final product of nicotine metabolism. Cotinine is mostly inactive in vertebrate nervous systems and is currently being explored as a molecule which possess most of nicotine’s beneficial effects and few of its undesirable ones. It is not known …

Beryllium Nitrate Inhibits Fibroblast Migration To Disrupt Epimorphic Regeneration, Adam B. Cook, Ashley W. Seifert

Biology Faculty Publications

Epimorphic regeneration proceeds with or without formation of a blastema, as observed for the limb and skin, respectively. Inhibition of epimorphic regeneration provides a means to interrogate the cellular and molecular mechanisms that regulate it. In this study, we show that exposing amputated limbs to beryllium nitrate disrupts blastema formation and causes severe patterning defects in limb regeneration. In contrast, exposing full-thickness skin wounds to beryllium only causes a delay in skin regeneration. By transplanting full-thickness skin from ubiquitous GFP-expressing axolotls to wild-type hosts, we demonstrate that beryllium inhibits fibroblast migration during limb and skin regeneration in vivo. Moreover, …

Correlation Analysis Of Enzyme Activities And Deconstruction Of Ammonia-Pretreated Switchgrass By Bacterial-Fungal Communities, Abhiney Jain, H. Sandra Pelle, J. Michael Henson

Biology Faculty Publications

The mixed microbial communities that occur naturally on lignocellulosic feedstocks can provide feedstock-specific enzyme mixtures to saccharify lignocelluloses. Bacterial-fungal communities were enriched from switchgrass bales to deconstruct ammonia-pretreated switchgrass (DSG). Correlation analysis was carried out to elucidate the relationship between microbial decomposition of DSG by these communities, enzymatic activities produced and enzymatic saccharification of DSG using these enzyme mixtures. Results of the analysis showed that β glucosidase activities and xylosidase activities limited the extent of microbial deconstruction and enzymatic saccharification of DSG. The results also underlined the importance of ligninase activity for the enzymatic saccharification of pretreated lignocellulosic feedstock. The …

Secondary Structure Adopted By The Gly-Gly-X Repetitive Regions Of Dragline Spider Silk, Geoffrey M. Gray, Arjan Van Der Vaart, Chengchen Guo, Justin A. Jones, David Onofrei, Brian R. Cherry, Randolph V. Lewis, Jeffery L. Yarger, Gregory P. Holland

Biology Faculty Publications

Solid-state NMR and molecular dynamics (MD) simulations are presented to help elucidate the molecular secondary structure of poly(Gly-Gly-X), which is one of the most common structural repetitive motifs found in orb-weaving dragline spider silk proteins. The combination of NMR and computational experiments provides insight into the molecular secondary structure of poly(Gly-Gly-X) segments and provides further support that these regions are disordered and primarily non-β-sheet. Furthermore, the combination of NMR and MD simulations illustrate the possibility for several secondary structural elements in the poly(Gly-Gly-X) regions of dragline silks, including β-turns, 310-helicies, and coil structures with a negligible population of α-helix observed.

Convergence In Nitrogen Deposition And Cryptic Isotopic Variation Across Urban And Agricultural Valleys In Northern Utah, Steven J. Hall, E. M. Ogata, Samantha R. Weintraub, Michelle A. Baker, James R. Ehleringer, C I. Czimczik, David R. Bowling

Biology Faculty Publications

The extent to which atmospheric nitrogen (N) deposition reflects land use differences and biogenic versus fossil fuel reactive N sources remains unclear yet represents a critical uncertainty in ecosystem N budgets. We compared N concentrations and isotopes in precipitation-event bulk (wet + dry) deposition across nearby valleys in northern Utah with contrasting land use (highly urban versus intensive agriculture/low-density urban). We predicted greater nitrate (NO3−) versus ammonium (NH4+) and higher δ15N of NO3− and NH4+ in urban valley sites. Contrary to expectations, annual N deposition (3.5–5.1 kg N ha−1 yr−1) and inorganic N concentrations were similar within and between valleys. …