ISSN:
1550-7408
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
SYNOPSIS. Studies were carried out on the introduction of labeled precursors into the DNA of Paramecium aurelia (syngen 4, stock 51) by way of the bacteria that are used for food. A thymine-requiring strain of Escherichia coli (15 T−) was labeled by growth in either H3-methyl thymidine or 2-C14 bromouracil, washed free of the exogenous label, and fed to the paramecia. The tritium label from the bacteria was incorporated almost exclusively into the DNA of the paramecia, whereas it was much less specifically incorporated when introduced directly from the medium. The Cu label from bromouracil was also incorporated mainly into the DNA of the paramecia although a small amount appeared in RNA. The formation of labeled food vacuoles was followed. Food vacuoles were formed at a nearly constant rate, with the total number of vacuoles increasing throughout the cycle. The lifetime of the vacuoles was about 2.5 hours. Incorporation of the label into the DXA of the paramecia begins within a few minutes of the formation of the first labeled vacuole. DNA synthesis begins about 1.5 hr after the previous fission (total cell cycle about 5.8 hr) and progresses at a nearly constant rate throughout the remainder of the cycle.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1550-7408.1964.tb01794.x
