Life Sciences Commons^™

Effect Of Intracellular Expression Of Antimicrobial Peptide Ll-37 On Growth Of Escherichia Coli Strain Top10 Under Aerobic And Anaerobic Conditions, Wei Liu, Shi Dong, Fei Xu, Xue Wang, T. Withers, Hongwei Yu, Xin Wang

Hongwei Yu

Antimicrobial peptides (AMPs) can cause lysis of target bacteria by directly inserting themselves into the lipid bilayer. This killing mechanism confounds the identification of the intracellular targets of AMPs. To circumvent this, we used a shuttle vector containing the inducible expression of a human cathelicidin-related AMP, LL-37, to examine its effect on Escherichia coli TOP10 under aerobic and anaerobic growth conditions. Induction of LL-37 caused growth inhibition and alteration in cell morphology to a filamentous phenotype. Further examination of the E. coli cell division protein FtsZ revealed that LL-37 did not interact with FtsZ. Moreover, intracellular expression of LL-37 results …

Synchronous Opening And Closing Motions Are Essential For Camp-Dependent Protein Kinase A Signaling, Atul K. Srivastava, Leanna R. Mcdonald, Alessandro Cembran, Jonggul Kim, Larry R. Masterson, Christopher L. Mcclendon, Susan S. Taylor, Gianluigi Veglia

Larry Masterson

Xk Aprosencephaly And Anencephaly In Sibs, Phillip Townes, Karen Reuter, E. Rosquete, B. Magee

B. Dale Magee

Recent studies have suggested a causal and pathogenetic relationship between holoprosencephaly and anencephaly. In support of the proposed relationship we report a sibship that includes anencephalic male twins and a female infant with a severe form of alobar holoprosencephaly, radial aplasia, and oligodactyly. The upper limb and brain malformations are considered to represent aprosencephaly syndrome. The coexistence of anencephaly and aprosencephaly within a sibship suggests that XK aprosencephaly syndrome may be an autosomal recessive disorder.

Plant Oil Based Soap, Laura Thompson

Laura K Thompson Dr

This laboratory is one in a series that I use in Biology 401: Applied Plant Science. This course is designed for students who have had at least one introductory Biology course, either for a major or a non-major. The goal in the course is to give the student an appreciation for the importance of plants to human society. Each laboratory session is designed to give the student an appreciation for how plants contribute to society and an experience in original processing of plants for their use. This laboratory session complements our lectures on the plant oil industry. Students work in …

A Multicentre Year-Long Randomised Controlled Trial Of Exercise Training Targeting Physical Functioning In Men With Prostate Cancer Previously Treated With Androgen Suppression And Radiation From Trog 03.04 Radar, Daniel Galvao, Nigel Spry, James Denham, Dennis Taaffe, Prue Cormie, David Joseph, David Lamb, Suzanne Chambers, Robert Newton

Prue Cormie

Background: Long-term prostate cancer (PCa) survivors are at increased risk for comorbidities and physical deconditioning. Objective: To determine the effectiveness of a year-long randomised controlled trial of exercise training in PCa survivors >5 yr postdiagnosis on physical functioning. Design, setting, and participants: Between 2010 and 2011, 100 long-term PCa survivors from Trans-Tasman Radiation Oncology Group 03.04 Randomised Androgen Deprivation and Radiotherapy previously treated with androgen-deprivation therapy and radiation therapy were randomly assigned to 6 mo of supervised exercise followed by 6 mo of a home-based maintenance programme (n = 50) or printed educational material about physical activity (n = 50) …

Exercise Maintains Sexual Activity In Men Undergoing Androgen Suppression For Prostate Cancer: A Randomized Controlled Trial, Prue Cormie, Robert Newton, Dennis Taaffe, Nigel Spry, David Joseph, M Akhlil Hamid, Daniel Galvao

Prue Cormie

Background:Previous research has shown exercise to be an effective method to mitigate many adverse treatment-related effects of androgen suppression therapy (AST) but the potential impact of exercise on sexual activity remains unknown. The purpose of this investigation was to report the effect of a 12-week exercise program on sexual activity in prostate cancer patients undergoing AST.Methods:Fifty-seven prostate cancer patients undergoing AST were randomly assigned to an exercise program (resistance and aerobic modes; n=29) or usual care control (n=28). Sexual activity was assessed by the European Organization for Research and Treatment of Cancer prostate cancer-specific quality of life questionnaire (QLQ-PR25).Results:QLQ-PR25 data …

Knee Angle-Specific Emg Normalization: The Use Of Polynomial Based Emg-Angle Relationships, J Earp, R Newton, Prue Cormie, A Blazevich

Prue Cormie

The normalization of EMG signals to those recorded during a maximal voluntary contraction provides a valid construct for comparisons of relative muscle activity. However, the length dependence of muscle activation and purported, substantial, muscle translocation and changes in muscle architecture during dynamic movements presents a need for joint angle-dependent normalization processes. The purposes of the present study were to: (1) quantify variations in muscle activity across a large ROM, (2) determine the accuracy with which fitted EMG-joint angle curves accurately characterized these variations, and (3) compare peak (EMG-P) and average (EMG-A) EMG amplitudes obtained during a countermovement leg extension when …

The Capacity To Vote Of Persons With Alzheimer's Disease, Paul Appelbaum, Richard Bonnie, Jason Karlawish

Jason Karlawish

OBJECTIVE: The right to vote can be abrogated when persons become incompetent to cast a ballot. This applies particularly to people with Alzheimer's disease, who at some point will lose capacity. A 2001 federal court decision offered the first clear criteria ("Doe voting capacity standard") for determining voting competence, focused on understanding the nature and effect of voting and on the ability to choose. This article explores how persons with Alzheimer's disease perform on these criteria. METHOD: The Doe standard was operationalized in a brief questionnaire, along with measures of appreciation and reasoning about voting choices. Performance was assessed in …

Beneath The Surface: Discovering The Unvoiced Concerns Of Older Adults With Type 2 Diabetes Mellitus, Jennifer Tjia, Jane Givens, Jason Karlawish, A. Okoli-Umeweni, Frances Barg

Jason Karlawish

Emerging clinical guidelines recommend shared decision making to individualize drug regimens for older adults with Type 2 diabetes mellitus. While the current health education campaign for diabetes in the United States recommends physician-initiated medication-related discussions about adherence and side effects, little emphasis is placed on soliciting patient concerns. This study's aim was to explore the concerns of older adults with diabetes about the complexity of their drug regimens and to determine whether they discussed medication-related concerns with their physician. Twenty-two patients with Type 2 diabetes age 65 years and older who used five or more medications were selected from an …

Differential Muscle Hypertrophy Is Associated With Satellite Cell Numbers And Akt Pathway Activation Following Activin Type Iib Receptor Inhibition In Mtm1 P.R69c Mice, Michael Lawlor, Marissa Viola, Hui Meng, Rachel Edelstein, Fujun Liu, Ke Yan, Elizabeth Luna, Alexandra Lerch-Gaggl, Raymond Hoffmann, Christopher Pierson, Anna Buj-Bello, Jennifer Lachey, Scott Pearsall, Lin Yang, Cecilia Hillard, Alan Beggs

Elizabeth J. Luna

X-linked myotubular myopathy is a congenital myopathy caused by deficiency of myotubularin. Patients often present with severe perinatal weakness, requiring mechanical ventilation to prevent death from respiratory failure. We recently reported that an activin receptor type IIB inhibitor produced hypertrophy of type 2b myofibers and modest increases of strength and life span in the severely myopathic Mtm1δ4 mouse model of X-linked myotubular myopathy. We have now performed a similar study in the less severely symptomatic Mtm1 p.R69C mouse in hopes of finding greater treatment efficacy. Activin receptor type IIB inhibitor treatment of Mtm1 p.R69C animals produced behavioral and histological evidence …

Darwin's Bark Spider: Giant Prey In Giant Orb Webs (Araneidae: Caerostris Darwini), Todd Blackledge, Matjaz Gregoric, Ingi Agnarsson, Matjaz Kuntner

Todd A. Blackledge

Although the diversity of spider orb web architectures is impressive, few lineages have evolved orb webs larger than lm in diameter. Until recently, such web gigantism was reported only in a few nephilids and araneids. However, new studies on bark spiders (Caerostris) of Madagascar report a unique case of web gigantism: Darwin's bark spider (C. darwini) casts its webs over substantial water bodies, and these webs are made from silk whose toughness outperforms all other known spider silks. Here we investigate C darwini web architecture and provide data to begin to answer two intriguing questions to explain these extraordinary web …

Conflicts Around A Study Of Mexican Crops., Todd Blackledge

Todd A. Blackledge

No abstract provided.

High-Performance Spider Webs: Integrating Biomechanics, Ecology And Behaviour, Todd Blackledge, Aaron Harmer, Joshua Madin, Marie Herberstein

Todd A. Blackledge

Spider silks exhibit remarkable properties, surpassing most natural and synthetic materials in both strength and toughness. Orb-web spider dragline silk is the focus of intense research by material scientists attempting to mimic these naturally produced fibres. However, biomechanical research on spider silks is often removed from the context of web ecology and spider foraging behaviour. Similarly, evolutionary and ecological research on spiders rarely considers the significance of silk properties. Here, we highlight the critical need to integrate biomechanical and ecological perspectives on spider silks to generate a better understanding of (i) how silk biomechanics and web architectures interacted to influence …

Darwin's Bark Spider: Giant Prey In Giant Orb Webs (Caerostris Darwini, Araneae: Araneidae), Todd Blackledge, Matjaz Gregoric, Ingi Agnarsson, Matjaz Kuntner

Todd A. Blackledge

Although the diversity of spider orb web architectures is impressive, few lineages have evolved orb webs larger than 1m in diameter. Until recently, such web gigantism was reported only in a few nephilids and araneids. However, new studies on bark spiders (Caerostris) of Madagascar report a unique case of web gigantism: Darwin’s bark spider (C. darwini) casts its webs over substantial water bodies, and these webs are made from silk whose toughness outperforms all other known spider silks. Here we investigate C. darwini web architecture and provide data to begin to answer two intriguing questions to explain these extraordinary web …

Spider Dragline Silk: Correlated And Mosaic Evolution In High-Performance Biological Materials, Todd Blackledge, Brook Swanson, Cheryl Hayashi, Adam Summers

Todd A. Blackledge

The evolution of biological materials is a critical, yet poorly understood, component in the generation of biodiversity. For example, the diversification of spiders is correlated with evolutionary changes in the way they use silk, and the material properties of these fibers, such as strength, toughness, extensibility, and stiffness, have profound effects on ecological function. Here, we examine the evolution of the material properties of dragline silk across a phylogenetically diverse sample of species in the Araneomorphae (true spiders). The silks we studied are generally stronger than other biological materials and tougher than most biological or man-made fibers, but their material …

Changes In The Adhesive Properties Of Spider Aggregate Glue During The Evolution Of Cobwebs, Todd Blackledge, Ali Dhinojwala, Vasav Sahni

Todd A. Blackledge

We compare the prey capture glues produced by orb-weaving spiders (viscid glue) and their evolutionary descendents, the cobweb-weaving spiders (gumfoot glue). These glues are produced in homologous glands but exhibit contrasting structure, properties and response to changing humidity. Individual glue droplet stretching measurements indicate that the gumfoot glue behaves like a viscoelastic liquid in contrast to the viscid glue, which behaves like a viscoelastic solid. Moreover, the gumfoot glue is largely humidity-resistant – elasticity and adhesion are constant across variation in humidity and there is weak volume-dependence. Viscid glue, however, is highly humidity-sensitive. The glue expands an order of magnitude …

The Evolution Of Cryptic Spider Silk: A Behavioral Test, Todd Blackledge, John Wenzel

Todd A. Blackledge

Phylogenetic patterns of change in spider silk coloration provide insight into the selective pressures directing evolution of silks. Trends toward evolution of silks with low reflectance of ultraviolet (UV) light suggest that reduced UV reflectance may be an adaptation to reduce visibility of webs to insect prey. However, a test of the visibility of primitive and derived spider silks is lacking. Several genera of orb-weaving spiders include conspicuous designs of silk, called “stabilimenta,” at the center of their webs. Due to their large size, stabilimenta present signals that insects can use to avoid webs. Unlike other silks in the orb …

Spider Capture Silk: Performance Implications Of Variation In An Exceptional Biomaterial, Todd Blackledge, Brook Swanson, Cheryl Hayashi

Todd A. Blackledge

Spiders and their silk are an excellent system for connecting the properties of biological materials to organismal ecology. Orb-weaving spiders spin sticky capture threads that are moderately strong but exceptionally extensible, resulting in fibers that can absorb remarkable amounts of energy. These tough fibers are thought to be adapted for arresting flying insects. Using tensile testing, we ask whether patterns can be discerned in the evolution of silk material properties and the ecological uses of spider capture fibers. Here, we present a large comparative data set that allows examination of capture silk properties across orb-weaving spider species. We find that …

Functionally Independent Components Of Prey Capture Are Architecturally Constrained In Spider Orb Webs, Todd Blackledge, Chad Eliason

Todd A. Blackledge

Evolutionary conflict in trait performance under different ecological contexts is common, but may also arise from functional coupling between traits operating within the same context. Orb webs first intercept and then retain insects long enough to be attacked by spiders. Improving either function increases prey capture and they are largely determined by different aspects of web architecture. We manipulated the mesh width of orbs to investigate its effect, along with web size, on prey capture by spiders and found that they functioned independently. Probability of prey capture increased with web size but was not affected by mesh width. Conversely, spiders …

Humidity Responsive Materials And Systems And Methods Using Humidity Responsive Materials, Todd Blackledge, Ali Dhinojwala, Ingi Agnarsson

Todd A. Blackledge

The invention relates to silk or other materials formed to have predetermined contraction/relaxation characteristics, wherein the contraction/relaxation characteristics are initiated by exposure thereof to predetermined humidity characteristics in the adjacent atmosphere. The materials may comprise a single silk fiber, a bundle of fibers of a predetermined size or diameter, a meshwork of fibers forming a predetermined configuration such as one or more sheets, bundles or other bodies. In this manner, the material can be scaled across a size range of any desired magnitude to produce predetermined force and/or displacement characteristics in association therewith.

How Super Is Supercontraction? Persistent Versus Cyclic Response To Humidity In Spider Dragline Silk, Todd Blackledge, Cecilia Boutry, Shing-Chung Wong, Avinash Baji

Todd A. Blackledge

Spider dragline silk has enormous potential for the development of biomimetic fibers that combine strength and elasticity in low density polymers. These applications necessitate understanding how silk reacts to different environmental conditions. For instance, spider dragline silk `supercontracts' in high humidity. During supercontraction, unrestrained dragline silk contracts up to 50% of its original length and restrained fibers generate substantial stress. Here we characterize the response of dragline silk to changes in humidity before, during and after supercontraction. Our findings demonstrate that dragline silk exhibits two qualitatively different responses to humidity. First, silk undergoes a previously unknown cyclic relaxation–contraction response to …

Fine Dining Or Fortress? Functional Shifts In Spider Web Architecture By The Western Black Widow Latrodectus Hesperus, Todd Blackledge, Jacquelyn Zevenbergen, Nicole Schneider

Todd A. Blackledge

Spiders alter web architecture in response to many environmental factors. Yet, the functional implications of this behavioural plasticity are poorly understood, especially for spiders that spin long-lasting webs such as cobwebs. The western black widow spins a three-dimensional web that captures terrestrial prey and can persist for many days. However, the shape of the cobweb depends upon changes in the spider's body condition. Starved spiders invest more silk in sticky gumfooted threads, whereas sated spiders invest more silk in supporting threads. We tested the hypothesis that the increased investment in sticky gumfooted threads by starved spiders functions to improve the …

Gumfooted Lines In Black Widow Cobwebs And The Mechanical Properties Of Spider Capture Silk, Todd Blackledge, Adam Summers, Cheryl Hayashi

Todd A. Blackledge

Orb-weaving spiders produce webs using two types of silk that have radically different mechanical properties. The dragline silk used to construct the supporting frame and radii of the web is stiff and as strong as steel, while the capture spiral is much weaker but more than ten times as extensible. This remarkable divergence in mechanical properties has been attributed to the aqueous glue that coats the capture spiral, which is thought to decrease capture spiral stiffness and increase its extensibility. However, discerning the effect of the aqueous glue on fiber performance is complicated because dragline silk and the capture spiral …

Bioprospecting Finds The Toughest Biological Material: Extraordinary Silk From A Giant Riverine Orb Spider, Todd Blackledge, Matjaz Kuntner, Ingi Agnarsson

Todd A. Blackledge

Background: Combining high strength and elasticity, spider silks are exceptionally tough, i.e., able to absorb massive kinetic energy before breaking. Spider silk is therefore a model polymer for development of high performance biomimetic fibers. There are over 41.000 described species of spiders, most spinning multiple types of silk. Thus we have available some 200.000+ unique silks that may cover an amazing breadth of material properties. To date, however, silks from only a few tens of species have been characterized, most chosen haphazardly as model organisms (Nephila) or simply from researchers' backyards. Are we limited to ‘blindly fishing’ in efforts to …

Evolution Of Supercontraction In Spider Silk: Structure-Function Relationship From Tarantulas To Orb-Weavers, Todd Blackledge, Cecilia Boutry

Todd A. Blackledge

Spider silk is a promising biomaterial with impressive performance. However, some spider silks also 'supercontract' when exposed to water, shrinking by up to ∼50% in length. Supercontraction may provide a critical mechanism to tailor silk properties, both for future synthetic silk production and by the spiders themselves. Several hypotheses are proposed for the mechanism and function of supercontraction, but they remain largely untested. In particular, supercontraction may result from a rearrangement of the GPGXX motif within the silk proteins, where G represents glycine, P proline and X is one of a small subset of amino acids. Supercontraction may prevent sagging …

Supercontraction Forces In Spider Dragline Silk Depend On Hydration Rate, Todd Blackledge, Cecilia Boutry, Ingi Agnarsson, Shing-Chung Wong

Todd A. Blackledge

Spider dragline silk is a model biological polymer for biomimetic research due to its many desirable and unusual properties. 'Supercontraction' describes the dramatic shrinking of dragline silk fibers when wetted. In restrained silk fibers, supercontraction generates substantial stresses of 40-50 MPa above a critical humidity of approximately 70% relative humidity (RH). This stress may maintain tension in webs under the weight of rain or dew and could be used in industry for robotics, sensor technology, and other applications. Our own findings indicate that supercontraction can generate stress over a much broader range than previously reported, from 10 to 140 MPa. …

Spider Silk: A Brief Review And Prospectus On Research Linking Biomechanics And Ecology In Draglines And Orb Webs, Todd Blackledge

Todd A. Blackledge

Spiders construct a wide variety of silk structures, ranging from draglines to prey capture webs. Spider silks rank among the toughest materials known to science, and these material properties are critical for understanding how silk structures, such as webs, function. However, the mechanics of spider silk are often ignored in the study of webs. This review aims to show how the material properties of silk proteins, the structural properties of silk threads, and the architectures of webs ultimately interact to determine the function of orb webs during prey capture. I first provide a brief introduction into spider silk and how …

Condition-Dependent Spider Web Architecture In The Western Black Widow, Latrodectus Hesperus, Todd Blackledge, Jacquelyn Zevenbergen

Todd A. Blackledge

Animals use behavioural plasticity to cope with conflicting selective pressures. We investigated how prey availability affects the spinning of cobwebs, whose architecture influences both prey capture and defence. Fed western black widows spun cobwebs containing more silk than did fasted spiders. However, fed spiders invested relatively less silk in the sheets and sticky gumfooted threads of webs and relatively more silk in supporting threads than did fasted spiders. The material properties of silk spun by fed and fasted spiders were relatively similar, but silk threads spun by fed spiders were twice as thick as those of fasted spiders, increasing web …

Signal Conflict In Spider Webs Driven By Predators And Prey, Todd Blackledge

Todd A. Blackledge

Variation in the sensory physiologies of organisms can bias the receptions of signals, driving the direction of signal evolution. Sensory drive in the evolution of signals may be particularly important for organisms that confront trade-offs in signal design between the need for conspicuousness to allow effective transfer of information and the need for crypsis of the signal to unintended receivers. Several genera of orb-weaving spiders include conspicuous silk designs, stabilimenta, in the centre of their webs. Stabilimenta can be highly visible signals to predators, warning them of the presence of a noxious, sticky silk web. However, stabilimenta can also be …

Spider Silk As A Novel High Performance Muscle Driven By Humidity, Todd Blackledge, Ali Dhinojwala, Ingi Agnarsson, Vasav Sahni

Todd A. Blackledge

The abrupt halt of a bumble bee's flight when it impacts the almost invisible threads of an orb web provides an elegant example of the amazing strength and toughness of spider silk. Spiders depend upon these properties for survival, yet the impressive performance of silk is not limited solely to tensile mechanics. Here, we show that silk also exhibits powerful cyclic contractions, allowing it to act as a high performance mimic of biological muscles. These contractions are actuated by changes in humidity alone and repeatedly generate work 50 times greater than the equivalent mass of human muscle. Although we demonstrate …