ABSTRACT
Cells can sense and process various signals. Noise is inevitable in the cell signaling system. In a bacterial community, the mutual conversion between normal cells and persistent cells forms a bidirectional phenotype switching cascade, in which either one can be used as an upstream signal and the other as a downstream signal. In order to quantitatively describe the relationship between noise and signal amplification of each phenotype, the gain-fluctuation relationship is obtained by using the linear noise approximation of the master equation. Through the simulation of these theoretical formulas, it is found that the bidirectional phenotype switching can directly generate interconversion noise which is usually very small and almost negligible. In particular, the bidirectional phenotype switching can provide a global fluctuating environment, which will not only affect the values of noise and covariance, but also generate additional intrinsic noise. The additional intrinsic noise in each phenotype is the main part of the total noise and can be transmitted to the other phenotype. The transmitted noise is also a powerful supplement to the total noise. Therefore, the indirect impact of bidirectional phenotype switching is far greater than its direct impact, which may be one of the reasons why chronic infections caused by persistent cells are refractory to treat.
ABSTRACT
Like genes and proteins, cells can use biochemical networks to sense and process information. The differentiation of the cell state in colonic crypts forms a typical unidirectional phenotypic transitional cascade, in which stem cells differentiate into the transit-amplifying cells (TACs), and TACs continue to differentiate into fully differentiated cells. In order to quantitatively describe the relationship between the noise of each compartment and the amplification of signals, the gain factor is introduced, and the gain-fluctuation relation is obtained by using the linear noise approximation of the master equation. Through the simulation of these theoretical formulas, the characters of noise propagation and amplification are studied. It is found that the transmitted noise is an important part of the total noise in each downstream cell. Therefore, a small number of downstream cells can only cause its small inherent noise, but the total noise may be very large due to the transmitted noise. The influence of the transmitted noise may be the indirect cause of colon cancer. In addition, the total noise of the downstream cells always has a minimum value. As long as a reasonable value of the gain factor is selected, the number of cells in colonic crypts will be controlled within the normal range. This may be a good method to intervene the uncontrollable growth of tumor cells and effectively control the deterioration of colon cancer.
Subject(s)
Colon/cytology , Models, Biological , Phenotype , Signal TransductionABSTRACT
Smoke water and distillation liquid were used to treat the seeds of Trichosathes kirilowii and to study the effects of smoke water and distillation liquid on the seed germination and seedling growth of T. kirilowii. The results showed that germination rate, germination index and germination vigor of T. kirilowii all were significantly improved with the treatment of SW and DL treatment. The activity of α-amylase were significantly increased with the treatment of SW and DL at 1:2,000. SW and DL treatment showed no significant effects on the activity of SOD. The activity of POD were markedly enhanced under the treatment of SW (1:000) and DL (1:2,000). CAT activity were increased with the treatment of SW and DL at 1:2,000 while were inhibited by SW and DL at 1:500. Seedling height and root length were increased with the treatment of SW and DL (1:1,000, 1:2,000). SW and DL treaments improved the content of chlorophyll, and moreover with the concentration of SW and DL, the stimulatory were also increased. This work demonstrated that smoke water and diatillation liquid at 1:2,000 could stimulate the seed germination and seedling growth of T. kirilowii, and it provided the references for the study of seed germination technology.
