Loss of Phosphate Determines the Versatility of a Spider Orb-web Glue Ball

Abstract

Spiders capture their prey by weaving an "invisible" orb-web that has both adhesive and fixed properties. Different types of silk in the orb-web have different functions, wherein the key to capturing a prey is the ball-like glue (glue ball), which coats the silk strands. This glue ball has highly versatile properties, but the mechanisms leading to its versatility remain unclear. The salts found in the web have been previously suggested to play an important role in terms of viscosity, not water. However, the distribution of salt and water in the glue ball has not yet been directly observed. Here, we mapped the salts in different states using a homemade time-of-flight secondary ion mass spectrometer (TOF-SIMS) with a high lateral resolution. To our surprise, the glue ball was found to contain little water. The functional transformation of the glue ball from a viscous glycoprotein (capturing prey) to a hardened protein (retaining prey) relies solely on the stimulation of mechanical forces. The phosphate is a key factor for its versatility.

Changes of Calcium Distribution in Glue Ball of Spider's Orb-web under Low-temperature Stress

“…The denaturation of glycoproteins after salt loss has been confirmed [2,13,15], suggesting that the salt may play an important role in the versatility of this substance. The distribution of salt in glue ball occurred significant changes after subjecting to various mechanical stimuli [2]. The occurrence of phase separation when glue ball was subjected to mechanical stimulation, especially after coming into contact with an object [2].…”

“…This sticky substance then transforms into a solidified substance that prevents the prey from breaking free [1]. This process relies solely on mechanical stimulation [2].…”

“…Based on the currently available information, we know that the main components of this viscous substance are glycoproteins [3][4][5] and salts [6][7][8][9][10][11][12][13][14]. The denaturation of glycoproteins after salt loss has been confirmed [2,13,15], suggesting that the salt may play an important role in the versatility of this substance. The distribution of salt in glue ball occurred significant changes after subjecting to various mechanical stimuli [2].…”

“…The distribution of salt in glue ball occurred significant changes after subjecting to various mechanical stimuli [2]. The occurrence of phase separation when glue ball was subjected to mechanical stimulation, especially after coming into contact with an object [2].…”

“…After an impact, induced phase separation leads to the loss of salt, which in turn leads to protein denaturation [2]. This suggests that the main function of salt in the web is to change the substance from a viscous material to one that fixes the prey to the web.…”