Yeast cells must grow to a critical size before committing to division. It is unknown how size is measured. We find that as cells grow, mRNAs for some cell-cycle activators scale faster than size, increasing in concentration, while mRNAs for some inhibitors scale slower than size, decreasing in concentration. Size-scaled gene expression could cause an increasing ratio of activators to inhibitors with size, triggering cell-cycle entry. Consistent with this, expression of the CLN2 activator from the promoter of the WHI5 inhibitor, or vice versa, interfered with cell size homeostasis, yielding a broader distribution of cell sizes. We suggest that size homeostasis comes from differential scaling of gene expression with size. Differential regulation of gene expression as a function of cell size could affect many cellular processes.

• Klíčová slova
• Cln3, cell cycle, cell cycle control, cell cycle regulation, cell size control, growth Whi5, growth control of division, size homeostasis, start, yeast cell cycle,
• MeSH
• buněčné dělení genetika   MeSH
• buněčný cyklus genetika   MeSH
• cykliny genetika   MeSH
• G1 fáze genetika   MeSH
• regulace genové exprese u hub genetika   MeSH
• Saccharomyces cerevisiae - proteiny genetika   MeSH
• Saccharomyces cerevisiae genetika   růst a vývoj   MeSH
• velikost buňky * MeSH
• vývojová regulace genové exprese genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• CLN2 protein, S cerevisiae MeSH Prohlížeč
• cykliny MeSH
• Saccharomyces cerevisiae - proteiny MeSH

Differentiation of Trypanosoma brucei, a flagellated protozoan parasite, between life cycle stages typically occurs through an asymmetric cell division process, producing two morphologically distinct daughter cells. Conversely, proliferative cell divisions produce two daughter cells, which look similar but are not identical. To examine in detail differences between the daughter cells of a proliferative division of procyclic T. brucei we used the recently identified constituents of the flagella connector. These segregate asymmetrically during cytokinesis allowing the new-flagellum and the old-flagellum daughters to be distinguished. We discovered that there are distinct morphological differences between the two daughters, with the new-flagellum daughter in particular re-modelling rapidly and extensively in early G1. This re-modelling process involves an increase in cell body, flagellum and flagellum attachment zone length and is accompanied by architectural changes to the anterior cell end. The old-flagellum daughter undergoes a different G1 re-modelling, however, despite this there was no difference in G1 duration of their respective cell cycles. This work demonstrates that the two daughters of a proliferative division of T. brucei are non-equivalent and enables more refined morphological analysis of mutant phenotypes. We suggest all proliferative divisions in T. brucei and related organisms will involve non-equivalence.

• MeSH
• buněčné dělení MeSH
• cytokineze MeSH
• flagella genetika   metabolismus   MeSH
• proliferace buněk MeSH
• protozoální proteiny genetika   metabolismus   MeSH
• stadia vývoje MeSH
• Trypanosoma brucei brucei cytologie   genetika   růst a vývoj   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• protozoální proteiny MeSH

Individual cells in chemostat cultures of Candida utilis (D = 0.05, 0.1, 0.2, 0.25, 0.3 and 35/h) were analyzed according to the number of bud scars and according to their position in the cell cycle. The distribution in the cell cycle phases depends both on the genealogical age and the specific rate of growth.

• MeSH
• buněčný cyklus MeSH
• Candida cytologie   růst a vývoj   MeSH
• časové faktory MeSH
• mykologie metody   MeSH
• Publikační typ
• časopisecké články MeSH