Revealing nucleoplasm mechanics by optical trapping and Brownian motion of nucleolus within mouse GV-oocytes in vivo

• Published in: Journal of physics. Conference series 2020-12, Vol.1695 (1), p.12052
• Main Authors: Syrchina, M S, Shakhov, A M, Aybush, A V, Zalessky, A D, Nadtochenko, V A
• Format: Article
• Language: English
• Subjects: Brownian motion; Gametocytes; In vivo methods and tests; Mouse devices; Optical trapping; Optical traps; Physics; Rheological properties; Rheology; Stress relaxation; Stress relaxation tests
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1695/1/012052

Optical trapping of nucleoli within nucleoplasm of living oocytes as unique model system provides non-invasive technique for investigation of nuclear environment. We employed methods of active and passive rheology to characterize rheological properties of the nucleoplasm of GV-oocytes (germinal vesicle stage) with main types of chromatin distribution in the nucleus (NSN, SN). By using of single beam optical trap, formed by a tightly focused laser radiation at 790 nm wavelength, we performed subsequent stress-relaxation tests series of nucleoli in various directions and with different amplitudes. Nucleolus of the oocyte was employed as a microprobe due to its large size and spherical shape. The characteristic nucleolus relaxation times were obtained for two types of chromatin distribution, which can subsequently be used to evaluate the viscoelastic properties of the nuclear material within oocytes with different physiological states. Motion activity of nucleoli was also extracted to evaluate local forces, acting within nucleolar environment and facilitating chromatin redistribution.