| For millennia,spiders have used their silk and venom to obtain their food,and the properties of silk and venom have continuously improved.Spider silk has good strength and toughness,and it is always the first choice of researchers who study the structure and properties of natural protein fiber materials.There is a wide variety of spiders,but most current studies focus on the structure and properties of the major ampullate silk of orb-web-building spiders such as Araneidae and Nephilidae.Research on the silk of funnel web spiders is rarely reported,and the major ampullate silk of Tetragnathidae and Psechridae has not been fully studied.Therefore,it is of great significance to analyse the relationship between the mechanical properties and structure of the funnel web silks and major ampullate silks of various web-building spiders.Spider venom is often used in scientific research as an effective pesticide and drug lead molecule.The current methods for studying the structure of spider venom usually require the separation and purification of the venom before the toxin is analysed with tools such as mass spectrometry and chromatography,but this process is complex and time-consuming.It is valuable to explore a method for fast and direct analysis of the structure of spider venom.Therefore,based on the species diversity of spiders in Yunnan province,this paper discusses the structure and mechanical properties of different spider silks and the structure of spider venom glands.The results are as follows.(1)The funnel web silks of Hippasa lycosina(H.lycosina,belonging to the family Lycosidae)and Macrothele bannaensis(M.bannaensis,belonging to the family Macrothelidae)were first investigated by tensile testing,Raman spectroscopy and X-ray diffraction(XRD).The results showed that in a nonstandard tensile performance test,the mechanical properties of H.lycosina silk were superior to those of M.bannaensis silk.XRD patterns showed that H.lycosina silk was more crystalline than M.bannaensis silk,which was consistent with their relative breaking forces.This was consistent with the theory that the higher crystallinity of the major ampullate silk could lead to better strength of the silk.The two kinds of spider silk were oriented materials similar to the major ampullate silk of orb-web-building spiders,and the locations of their characteristic peaks were similar,indicating that the secondary structures of the protein were similar despite the different methods of spider web making.(2)The protein conformation and mechanical properties of the web frame silks from spiders of seven different species were analysed.The web frame silk in one of the major ampullate silks,and research on silk from Araneidae was rich.To make the results more comparable,the web frame silk of Araneidae was selected as the representative material,and the web frame silks of other families were grouped and compared with the silk of Araneidae.For the most of studied silks,the most of secondary structures from each silk fiber were all coaxially parallel to the fiber axis,the content of hydrogen-bonded Tyr,β-sheets and the crystallinity were higher,and correspondingly,the silks had a better strength;the degree of orientation of theβ-sheets wass higher,and correspondingly,the silks had a worse flexibility.But the results for Cyclosa nigra(C.nigra,belonging to the family Araneidae)silk and Achaearanea celsabdomina(A.celsabdomina,belonging to the family Theridiidae)silk were subtly different.Their β-sheets were oriented parallel to the fiber axis,and the degree of orientation in the β-sheets of A.celsabdomina silk was greater than that of C.nigra silk,but most of the other secondary structures in the A.celsabdomina silk were oriented perpendicular to the fiber axis.As a result,A.celsabdomina silk exhibited a higher ultimate strain(42.18 ± 11.84%)than C.nigra silk(23.85 ± 5.18%).Thus,the extensibility of spider silk was related to the orientations of all secondary structures,which include β-sheets.(3)In the study and classification of the structure of the web frame silks from six Araneidae spiders and two Tetragnathidae spiders,the Raman spectra of the silks of the Araneidae spiders(Gasteracantha diadesmia,Gasteracantha kuhli,Macracantha arcuata;and P.dehaani,A.gratiolus and C.nigra,which were studied above)and Tetragnathidae spiders(Leucauge tessellata and H.ornatissima,which was studied above)showed that the slight spectral differences might enable preliminary identification and classification of spiders.(4)In situ Raman microspectroscopy was first used to determine the secondary structure of the proteins,which were the active ingredients in venom glands,and venom glands were obtained from eight spiders: H.lycosina,Lycosa grahami,Lycosa wangi,Lycosa yunnanensis,Heteropoda venatoria,P.ghecuanus,Macrothele yani and Macrothele yunnanica.Their strongest peaks of Raman spectra were similar to those reported in the literature for purified spider venom,and the results indicated that part of the principal components of venom glands and venom were consistent.At the same time,the components of all eight spider venom glands contained carotenoids,and the glands had similar strongest Raman peaks,showing that the studied spider venom glands had similar secondary protein structures.However,there were some differences in the weaker peaks and relative intensity ratios,and the differences provided preliminary classification of the eight spiders.Finally,in situ Raman spectroscopy was an effective method with good repeatability and stability for the study of spider venom glands.In this paper,the mechanical properties and structures of different kinds of spider silk are investigated,and the structures of active protein components of spider venom glands are analysed quickly and directly.The research results enrich the scope of research on the properties and structures of spider silks,provide a new method to study the structure of spider venom,and provide a theoretical basis for the development and utilization of spider silk and spider venom. |
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