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

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

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

Anterior knee pain from the evolutionary perspective

Background This paper describes the evolutionary changes in morphology and orientation of the PFJ using species present through our ancestry over 340 million years. Methods 37 specimens from the Devonian period to modern day were scanned using a 64-slice CT scanner. 3D geometries were created following routine segmentation and anatomical measurements taken from standardised bony landmarks. Results Findings are described according to gait strategy and age. The adoption of an upright bi-pedal stance caused a dramatic change in the loading of the PFJ which has subsequently led to changes in the arrangement of the PFJ. From Devonian to Miocene periods, our sprawling and climbing ancestors possessed a broad knee with a shallow, centrally located trochlea. A more rounded knee was present from the Paleolithic period onwards in erect and bipedal gait types (aspect ratio 0.93 vs 1.2 in late Devonian), with the PFJ being placed lateral to the midline compared to the medial position in quadrapeds. The depth of the trochlea groove was maximal in the Miocene period of the African ground apes with associated acute sulcus angles in Gorilla (117°) becoming more flattened towards the modern human (138°). Conclusions The evolving bipedal gait lead to anteriorisation of the patellofemoral joint, flattening of the trochlea sulcus, in a more lateral, dislocation prone arrangement. Ancestral developments might help explain the variety of presentations of anterior knee pain and patellofemoral instability

The Elephant Evolved p53 Isoforms that Escape MDM2-Mediated Repression and Cancer

The p53 tumor suppressor is a transcription factor with roles in cell development, apoptosis, oncogenesis, aging, and homeostasis in response to stresses and infections. p53 is tightly regulated by the MDM2 E3 ubiquitin ligase. The p53-MDM2 pathway has coevolved, with MDM2 remaining largely conserved, whereas the TP53 gene morphed into various isoforms. Studies on prevertebrate ancestral homologs revealed the transition from an environmentally induced mechanism activating p53 to a tightly regulated system involving cell signaling. The evolution of this mechanism depends on structural changes in the interacting protein motifs. Elephants such as Loxodonta africana constitute ideal models to investigate this coevolution as they are large and long-living as well as having 20 copies of TP53 isoformic sequences expressing a variety of BOX-I MDM2-binding motifs. Collectively, these isoforms would enhance sensitivity to cellular stresses, such as DNA damage, presumably accounting for strong cancer defenses and other adaptations favoring healthy aging. Here we investigate the molecular evolution of the p53-MDM2 system by combining in silico modeling and in vitro assays to explore structural and functional aspects of p53 isoforms retaining the MDM2 interaction, whereas forming distinct pools of cell signaling. The methodology used demonstrates, for the first time that in silico docking simulations can be used to explore functional aspects of elephant p53 isoforms. Our observations elucidate structural and mechanistic aspects of p53 regulation, facilitate understanding of complex cell signaling, and suggest testable hypotheses of p53 evolution referencing Peto's Paradox