BEGIN:VCALENDAR
VERSION:2.0
PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:Atsushi Mochizuki (Kyoto University)
DTSTART:20241121T160000Z
DTEND:20241121T163000Z
DTSTAMP:20260421T124012Z
UID:MoRN/105
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/MoRN/105/">B
 iological functions and functional modules originated in structure of chem
 ical reaction network</a>\nby Atsushi Mochizuki (Kyoto University) as part
  of Seminar on the Mathematics of Reaction Networks\n\n\nAbstract\nIn livi
 ng cells\, chemical reactions are connected by sharing their products and 
 substrates\, and form a complex network system. Biological functions arise
  from the dynamics of chemical reaction networks\, and are regulated by ch
 anges in the amount/activity of enzymes that catalyze reactions in the sys
 tem. In this talk\, I will introduce our recent theoretical approach to de
 termine the behaviors of chemical reaction systems caused by changes in th
 e amount/activity of enzymes\, based solely on network topology. (1) We fo
 und that the qualitative response of chemical concentrations (and reaction
  fluxes) to changes in enzyme amount/activity can be determined from the n
 etwork structure alone. (2) Non-zero responses are localized to finite ran
 ges in a network\, and each range is determined by a subnetwork called a 
 “buffering structure”. The buffering structure is defined by the follo
 wing equation from local topology of a network 𝜒≔−(# of chemicals)+
 (# of reactions)−(# of cycles)+(# of conserved quantities)=0 where the i
 ndex 𝜒 is analogous to the Euler characteristic. We proved that any per
 turbation of a reaction parameter inside a buffering structure only affect
 s the concentrations and fluxes inside the buffering structure\, and does 
 not affect the concentrations and fluxes outside. Finally\, (3) buffering 
 structures govern the bifurcation of the steady state of a reaction networ
 k. The bifurcation behaviors are localized to finite regions within a netw
 ork\, and these regions are again determined by buffering structures. Thes
 e results imply that the buffering structures may be the origin of the mod
 ularity of biological functions derived from reaction networks. We applied
  this method to the cell cycle system and demonstrated that the regulation
  of different checkpoints is achieved by buffering structures.\n\nReferenc
 es\n\nMochizuki A. & Fiedler B. (2015) J. Theor. Biol. 367\, 189-202.\n\nO
 kada T. & Mochizuki A. (2016) Phys. Rev. Lett. 117\, 048101\n\nOkada T. & 
 Mochizuki A. (2017) Phys. Rev. E 96\, 022322\n\nYamauchi\, Hishida\, Okada
 \, Mochizuki (2024) Phys. Rev. Research 6\, 023150\n\nYamauchi\, et al. (I
 n preparation)\n
LOCATION:https://researchseminars.org/talk/MoRN/105/
END:VEVENT
END:VCALENDAR