Design features of the orb web of the spider, Araneus diadematus

Analysis of orb webs of the garden cross spider (Araneus diadematus) showed that these vertical webs have a significant up/down asymmetry. Experiments demonstrated that the spider runs down faster than up, and thus confers a relatively higher foraging value to sections below the hub. Simulations suggested that the density of capture spiral spacing, prey size, and the density of prey should all affect the capture efficiency of a web. Webs lose effective capture area because of overlap of the capture zone around each thread; the smaller the prey, the finer the mesh can be without losing effective area. Lower sectors of the web have a particular mesh size (height and length of capture spiral segments) throughout, whereas in the upper sectors the mesh size changes, widening from the hub towards the peripher

The complexity of silk under the spotlight of synthetic biology

Abstract For centuries silkworm filaments have been the focus of R&D innovation centred on textile manufacture with high added value. Most recently, silk research has focused on more fundamental issues concerning bio-polymer structure-property-function relationships. This essay outlines the complexity and fundamentals of silk spinning, and presents arguments for establishing this substance as an interesting and important subject at the interface of systems biology (discovery) and synthetic biology (translation). It is argued that silk is a generic class of materials where each type of silk presents a different embodiment of emergent properties that combine genetically determined (anticipatory) and environmentally responsive components. In spiders' webs the various silks have evolved to form the interactive components of an intricate fabric that provides an extended phenotype to the spider's body morphology

Demineralization enables reeling of wild Silkmoth cocoons

Wild Silkmoth cocoons are difficult or impossible to reel under conditions that work well for cocoons of the Mulberry silkmoth, Bombyx mori. Here we report evidence that this is caused by mineral reinforcement of Wild Silkmoth cocoons and that washing these minerals out allows for the reeling of commercial lengths of good quality fibers with implications for the development of the “Wild Silk” industry. We show that in the Lasiocampid silkmoth Gonometa postica, the mineral is whewellite (calcium oxalate monohydrate). Evidence is presented that its selective removal by ethylenediaminetetraacetic acid (EDTA) leaves the gum substantially intact, preventing collapse and entanglement of the network of fibroin brins, enabling wet reeling. Therefore, this method clearly differs from the standard “degumming” and should be referred to as “demineralizing”. Mechanical testing shows that such preparation results in reeled silks with markedly improved breaking load and extension to break by avoiding the damage produced by the rather harsh degumming, carding, or dry reeling methods currently in use, what may be important for the development of the silk industries not only in Asia but also in Africa and South America

Bee Threat Elicits Alarm Call in African Elephants

Unlike the smaller and more vulnerable mammals, African elephants have relatively few predators that threaten their survival. The sound of disturbed African honeybees Apis meliffera scutellata causes African elephants Loxodonta africana to retreat and produce warning vocalizations that lead other elephants to join the flight. In our first experiment, audio playbacks of bee sounds induced elephants to retreat and elicited more head-shaking and dusting, reactive behaviors that may prevent bee stings, compared to white noise control playbacks. Most importantly, elephants produced distinctive “rumble” vocalizations in response to bee sounds. These rumbles exhibited an upward shift in the second formant location, which implies active vocal tract modulation, compared to rumbles made in response to white noise playbacks. In a second experiment, audio playbacks of these rumbles produced in response to bees elicited increased headshaking, and further and faster retreat behavior in other elephants, compared to control rumble playbacks with lower second formant frequencies. These responses to the bee rumble stimuli occurred in the absence of any bees or bee sounds. This suggests that these elephant rumbles may function as referential signals, in which a formant frequency shift alerts nearby elephants about an external threat, in this case, the threat of bees

Thermal stress, p53 structures and learning from elephants

As species adapt to climatic changes, temperature-dependent functions of p53 in development, metabolism and cancer will adapt as well. Structural analyses of p53 epitopes interacting in response to environmental stressors, such as heat, may uncover physiologically relevant functions of p53 in cell regulation and genomic adaptations. Here we explore the multiple p53 elephant paradigm with an experimentally validated in silico model showing that under heat stress some p53 copies escape negative regulation by the MDM2 E3 ubiquitin ligase. Multiple p53 isoforms have evolved naturally in the elephant thus presenting a unique experimental system to study the scope of p53 functions and the contribution of environmental stressors to DNA damage. We assert that fundamental insights derived from studies of a historically heat-challenged mammal will provide important insights directly relevant to human biology in the light of climate change when ‘heat’ may introduce novel challenges to our bodies and health

From spider webs to a fibre-optic chemical sensor

From the spider’s perspective, silk is not only a building material but also a safety net, a weapon and a sensory organ to detect the presence of prey on its web. For scientists, dragline silk - directly extracted from spiders - is a tough, biodegradable and biocompatible optical fibre. These protein optical threads are made up of millions of repetitive protein sequences and domains that, unlike its silica counterpart, can interact with a multitude of chemical species. In this communication, we will explore the potential of using spider silk as a new type of fibre-optic chemical sensor

Dry-Spun Silk Produces Native-Like Fibroin Solutions

Silk's outstanding mechanical properties and energy efficient solidification mechanisms provide inspiration for biomaterial self-assembly as well as offering a diverse platform of materials suitable for many biotechnology applications. Experiments now reveal that the mulberry silkworm Bombyx mori secretes its silk in a practically "unspun" state that retains much of the solvent water and exhibits a surprisingly low degree of molecular order (β-sheet crystallinity) compared to the state found in a fully formed and matured fiber. These new observations challenge the general understanding of silk spinning and in particular the role of the spinning duct for structure development. Building on this discovery we report that silk spun in low humidity appears to arrest a molecular annealing process crucial for β-sheet formation. This, in turn, has significant positive implications, enabling the production of a high fidelity reconstituted silk fibroin with properties akin to the gold standard of unspun native silk

Accelerometers in collars identify behavioral states in captive African elephants Loxodonta africana

Accelerometers are motion-detection devices that, when attached to animals, are capable of detecting body orientation, overall activity levels, and specific behavior patterns. We deployed accelerometers in order to study the hypothesis that accelerometer output would allow us to distinguish between 4 behavior patterns in 3 adult female African elephants Loxodonta africana at Disney’s Animal Kingdom®, Florida, USA. Tri-axial accelerometer data loggers were attached to the tops of collars worn around the elephants’ necks. Behavior was documented on video while the accelerometer output was stored on the data logger. Feeding, bathing, and walking behaviors were recorded in all 3 subjects, while swaying behavior could be recorded in only 1 subject. Data in the 3 physical dimensions (sway, surge, and heave) were analyzed in terms of overall magnitude of movement (dynamic acceleration) and in terms of the periodicity of movement. When classifying accelerometer data of unlabeled origin to the correct behavioral state, overall success ranged from 70 to 91%. Bathing was sometimes confused with feeding and walking, but feeding, walking, and swaying were easily distinguished from each other. These results show that data from accelerometers can distinguish an elephant’s behavioral states, and thus may be used to monitor elephant behavior remotely. Such devices could be deployed for a variety of purposes, ranging from monitoring elephant activity in zoos to an early-warning system that could alert the authorities when wild elephants are being illegally hunted

Spider silk thread as a fiber optic chemical sensor

Monitoring the properties of light transmitted through a thread of spider silk enables detection of trace amounts of chemical compounds