Whole-Genome sequencing of the schizomid arachnid Rowlandius potiguar Santos, Ferreira and Buzzato, 2013 from the caves of the Brazilian semiarid

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  Image Credit: CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=40194191 Whole-Genome sequencing of the schizomid arachnid Rowlandius potiguar Santos, Ferreira and Buzzato, 2013 from the caves of the Brazilian semiarid Abstract Short-tailed whip scorpions (Arachnida: Schizomida) are a poorly studied group of arachnids, particularly in terms of genomic resources, despite their ecological and evolutionary relevance in subterranean environments. In this study, we present the first draft genome assembly of Rowlandius potiguar, a cave-associated species endemic to karst systems of northeastern Brazil. Genomic DNA was sequenced using Illumina paired-end technology (2 × 150 bp), and reads were assembled using a de novo assembly pipeline. The resulting genome assembly has a total length of 1.8 Gb, distributed across 1,505,104 scaffolds and 1,510,944 contigs, indicating a highly fragmented assembly. The scaffold N50 and contig N50 values were both 3.2 kb, and the GC content was ...

Tensile properties of single- and multi-type mixed fibre bundles of spider silk

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Tensile properties of single- and multi-type mixed fibre bundles of spider silk

Abstract

Spider silk is known for its outstanding toughness at low density, making it a promising model for the biomimetic design of advanced fibre materials. Spiders naturally do not spin single silk fibres but instead produce bundles, or threads, composed of two or more fibres that may originate from the same or different silk glands. Despite their ubiquity, the mechanical properties of these fibre bundles have been largely overlooked. In this study, both naturally spun and forcibly silked fibre bundles from the cosmopolitan cellar spider Pholcus phalangioides (Pholcidae) and naturally spun bundles from the comb-footed cellar spider Nesticus cellulanus (Nesticidae) were examined to test whether post-spinning combinations of different silk materials, such as stiff and soft fibres, enhance the toughness of silk bundles. Despite their compositional diversity, tensile tests showed that the performance of fibre bundles cannot be predicted solely from the properties or the number of the individual fibres. These findings reveal that silk fibre bundles exhibit more complex tensile behaviour than previously recognised and demonstrate that spiders can produce a wide range of mechanical properties through the specific post-processing and combination of silk fibres. This principle of forming heterogeneous bundles may inspire biomimetic approaches to the post-spinning processing of recombinant silks and the design of advanced fibre materials.

Promnil, S. M., Liprandi, D., Illing, T., Jani, M., Heinz, P., & Wolff, J. (2026). Tensile properties of single-and multi-type mixed fibre bundles of spider silk. Soft Matter. Advance online publication. https://doi.org/10.1039/D5SM01141H