ABSTRACT
Materials made of recombinant spider silk proteins are promising candidates for cardiac tissue engineering, and their suitability has so far been investigated utilizing primary rat cardiomyocytes. Herein, we expanded the tool box of available spider silk variants and demonstrated for the first time that human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes attach, contract, and respond to pharmacological treatment using phenylephrine and verapamil on explicit spider silk films. The hiPSC-cardiomyocytes contracted for at least 14 days on films made of positively charged engineered Araneus diadematus fibroin 4 (eADF4(κ16)) and three different arginyl-glycyl-aspartic acid (RGD)-tagged spider silk variants (positively or negatively charged and uncharged). Notably, hiPSC-cardiomyocytes exhibited different morphologies depending on the spider silk variant used, with less spreading and being smaller on films made of eADF4(κ16) than on RGD-tagged spider silk films. These results indicate that spider silk engineering is a powerful tool to provide new materials suitable for hiPSC-based cardiac tissue engineering.
ABSTRACT
Many laboratory experiments demonstrate how orb-web spiders change the architecture of their webs in response to prey, surroundings and wind loading. The overall shape of the web and a range of other web parameters are determined by frame and anchor threads. In the wild, unlike the lab, the anchor threads are attached to branches and leaves that are not stationary but move, which affects the thread tension field. Here we experimentally test the effect of a moving support structure on the construction behaviour and web-parameters of the garden cross spider Araneus diadematus. We found no significant differences in building behaviour between rigid and moving anchors in total time spent and total distance covered nor in the percentage of the total time spent and distance covered to build the three major web components: radials, auxiliary and capture spirals. Moreover, measured key parameters of web-geometry were equally unaffected. These results call for re-evaluation of common understanding of spider webs as thread tensions are often considered to be a major factor guiding the spider during construction and web-operation.
Subject(s)
Behavior, Animal/physiology , Environment , Spiders/physiology , AnimalsABSTRACT
Web spiders rely on vibrations propagated via their web to identify, locate and capture entangled prey. Here, we experimentally tested the robustness of the orb weaver's predation strategy when webs are severely distorted and silk tensions are drastically altered throughout the web, a common occurrence in the wild. We assessed prey identification efficiency by comparing the spider's initial reaction times towards a fruit fly trapped in the web, we measured location efficiency by comparing times and number of tugging bouts performed, and we determined capture efficiency by comparing capture times. It emerged that spiders are capable of identifying, locating and capturing prey in distorted webs, albeit taking somewhat longer to do so.
Subject(s)
Spiders , Animals , Predatory Behavior , Silk , VibrationABSTRACT
A spider's web is a multifunctional structure that captures prey and provides an information platform that transmits vibrational information. Many physical factors interact to influence web vibration and information content, from vibration source properties and input location, to web physical properties and geometry. The aim of the study was to test whether orb web vibration contains information about the location of the source of vibration. We used finite-element analysis model webs to control and vary major physical factors, investigating webs where spiders use a direct or remote monitoring strategy. When monitoring with eight sensors (legs) at the web centre, a comparison of longitudinal and transverse wave amplitude between the sensors gave sufficient information to determine source direction and distance, respectively. These localization cues were robust to changes in source amplitude, input angle and location, with increased accuracy at lower source amplitudes. When remotely monitoring the web using a single thread connected to the web's hub (a signal thread), we found that locational information was not available when the angle of the source input was unknown. Furthermore, a free sector and a stiff hub were physical mechanisms to aid information transfer, which provides insights for bioinspired fibre networks for sensing technologies.
Subject(s)
Predatory Behavior , Spiders/physiology , Vibration , AnimalsABSTRACT
Spider orb webs are multifunctional, acting to absorb prey impact energy and transmit vibratory information to the spider. This paper explores the links between silk material properties, propagation of vibrations within webs and the ability of the spider to control and balance web function. Combining experimental and modelling approaches, we contrast transverse and longitudinal wave propagation in the web. It emerged that both transverse and longitudinal wave amplitude in the web can be adjusted through changes in web tension and dragline silk stiffness, i.e. properties that can be controlled by the spider. In particular, we propose that dragline silk supercontraction may have evolved as a control mechanism for these multifunctional fibres. The various degrees of active influence on web engineering reveals the extraordinary ability of spiders to shape the physical properties of their self-made materials and architectures to affect biological functionality, balancing trade-offs between structural and sensory functions.
Subject(s)
Silk , Spiders , Stress, Mechanical , Vibration , AnimalsABSTRACT
Prior to make a new cobweb, the Araneus diadematus Clerck cross spider eats its old web regulary everyday. In this paper we issue a quantitative and qualitative analysis of pollen grains and fungal spores present in the cob web, which might contribute to the diet of this arachnide. Cob webs were collected at the Natural Park of Ticino (Pavia, northern Italy). Fungal spores and pollen grains were taxonomically counted and identified for each sample. Quantitative analysis showed that both spores and pollen present in the cob webs exhibited some seasonal variation as regards quantity, whereas the qualitative analysis revealed that spores and pollen grains belong to 14 and 7 taxa, respectively. Alternaria, Cladosporium, Fusarum were the most frequent fungal taxa while Urticaceae, Betulaceae and Poaceae became the most representative plant families. About 5700 fungal spores and 2000 pollen grains were found to be present in the cob web of this spider everyday. Based on this information, it is possible to think that the aeroplancton stuck to the cob web can become a nutritional additive for the diet of this arachnide.
Antes de fabricar su telaraña, la araña del jardín Araneus diadematus Clerck, regularmente, cada día se come la antigua. En este estudio aportamos un análisis cuantitativo y cualitativo de los granos de polen y Esporas fúngicas retenidas en la telaraña, los cuales podrían contribuir a la dieta de este arácnido. Las telarañas fueron colectadas en el Parque Natural del Ticino (Pavia, N. Italia). Para cada muestra, las esporas fúngicas y los granos de polen fueron contabilizados e identificados taxonómicamente. El análisis cuantitativo mostró que las esporas y el polen retenidos en las telarañas presentaron variación estacional en cantidad, mientras con el análisis cualitativo se determinó que las esporas y los granos de polen pertenecen a 14 y 7 taxa respectivamente. Alternaria, Cladosporium, Fusarium fueron los taxa fúngicos más frecuentes, mientras Urticaceae, Betulaceae y Poaceae fueron las familias de plantas más representadas. Se determinó que aproximadamente unas 5700 esporas fúngicas y 2000 granos de polen fueron retenidos en la tela de esta araña cada día. Con estos antecedentes, se puede pensar que el aeroplanctón adherido a la telaraña puede constituir una aporte nutritivo en la dieta de este arácnido.
