國立虎尾科技大學 |

Regulation of Cell Cycle Events in a Temperature Sensitive Chinese Hamster Cell Cycle Mutant.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Regulation of Cell Cycle Events in a Temperature Sensitive Chinese Hamster Cell Cycle Mutant./
Author:	Otsuka, Fyllis Susan Landy.
Description:	1 online resource (201 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 41-07, Section: B.
Contained By:	Dissertations Abstracts International41-07B.
Subject:	Biology. -
Online resource:	click for full text (PQDT)
ISBN:	9798661474407

Regulation of Cell Cycle Events in a Temperature Sensitive Chinese Hamster Cell Cycle Mutant.
Otsuka, Fyllis Susan Landy.

Regulation of Cell Cycle Events in a Temperature Sensitive Chinese Hamster Cell Cycle Mutant. - 1 online resource (201 pages)

Source: Dissertations Abstracts International, Volume: 41-07, Section: B.

Thesis (Ph.D.)--University of California, San Diego, 1980.

Includes bibliographical references

The regulation of cell cycle events has been investigated in a temperature-sensitive Chinese hamster cell cycle mutant. The mutant arrests in the G(,1) period of the cell cycle when placed at the nonpermissive temperature of 40.8(DEGREES)C. The onset of DNA synthesis is inhibited under these conditions, however, RNA and protein synthesis, in general, are not affected. Two-dimensional gel electrophoresis has confirmed that protein synthesis, per se, is normal at 40.8(DEGREES)C when compared to that seen at the permissive temperature of 34(DEGREES)C. There are, however, several differences between the electrophoretic profiles of proteins from mutant and wild-type cells. The biochemical characterization was extended to examine the induction of three specific cell cycle proteins, ornithine decarboxylase, S-adenosyl methionine decarboxylase, and thymidine kinase. The levels of activity of all three enzymes appear to be normal in mutant cells grown at 34(DEGREES)C when compared to the levels seen in the wild-type cells. At 40.8(DEGREES)C, however, there is a substantial reduction in the amount of ornithine decarboxylase activity and the amount of thymidine kinase activity is almost negligible. S-adenosyl methionine activity appears to be unaffected by the high temperature. Messenger RNA synthesis is necessary for the observed increase in ornithine decarboxylase and S-adenosyl methionine decarboxylase activities and this transcription occurs at both temperatures early in G(,1). The synthesis of thymidine kinase messenger RNA is also required before induction of this enzyme can occur. At 34(DEGREES)C, the production of this messenger RNA occurs immediately before the enzyme is induced while at 40.8(DEGREES)C, no thymidine kinase messenger RNA is made. The decrease in ornithine decarboxylase activity, therefore, appears to be due to some alteration at the posttranscriptional level, while the block of thymidine kinase induction appears to be at the level of transcription. The G(,1) arrest at 40.8(DEGREES)C is not the result of the decreased ornithine decarboxylase levels. The low levels of enzyme appear to produce enough putrescine such that the rest of the polyamine pathway can operate normally. Furthermore, addition of exogenous polyamines to the growth medium does not alleviate the cell cycle arrest seen at this temperature. The final section of this thesis describes attempts that were made to purify ornithine decarboxylase from the cultured cells. The enzyme is quite unstable after the final step of the purification, for unless a carrier protein is added to the collected fractions it loses activity within 24 hours. Presently, this system is not feasible for use in purifying large quantities of purified enzyme since the yield from each experiment is quite low. Further work, aimed at improving the yield of ornithine decarboxylase, is currently an ongoing project in this laboratory.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798661474407Subjects--Topical Terms:

599573
Biology.
Index Terms--Genre/Form:

554714
Electronic books.

Regulation of Cell Cycle Events in a Temperature Sensitive Chinese Hamster Cell Cycle Mutant.
LDR:04133ntm a22003137 4500 001 1142284
005 20240416125345.5
006 m o d
007 cr mn ---uuuuu
008 250605s1980 xx obm 000 0 eng d
020 $a 9798661474407
035 $a (MiAaPQ)AAI8018793
035 $a AAI8018793
040 $a MiAaPQ $b eng $c MiAaPQ $d NTU
100 1 $a Otsuka, Fyllis Susan Landy. $3 1466565
245 1 0 $a Regulation of Cell Cycle Events in a Temperature Sensitive Chinese Hamster Cell Cycle Mutant.
264 0 $c 1980
300 $a 1 online resource (201 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Dissertations Abstracts International, Volume: 41-07, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
502 $a Thesis (Ph.D.)--University of California, San Diego, 1980.
504 $a Includes bibliographical references
520 $a The regulation of cell cycle events has been investigated in a temperature-sensitive Chinese hamster cell cycle mutant. The mutant arrests in the G(,1) period of the cell cycle when placed at the nonpermissive temperature of 40.8(DEGREES)C. The onset of DNA synthesis is inhibited under these conditions, however, RNA and protein synthesis, in general, are not affected. Two-dimensional gel electrophoresis has confirmed that protein synthesis, per se, is normal at 40.8(DEGREES)C when compared to that seen at the permissive temperature of 34(DEGREES)C. There are, however, several differences between the electrophoretic profiles of proteins from mutant and wild-type cells. The biochemical characterization was extended to examine the induction of three specific cell cycle proteins, ornithine decarboxylase, S-adenosyl methionine decarboxylase, and thymidine kinase. The levels of activity of all three enzymes appear to be normal in mutant cells grown at 34(DEGREES)C when compared to the levels seen in the wild-type cells. At 40.8(DEGREES)C, however, there is a substantial reduction in the amount of ornithine decarboxylase activity and the amount of thymidine kinase activity is almost negligible. S-adenosyl methionine activity appears to be unaffected by the high temperature. Messenger RNA synthesis is necessary for the observed increase in ornithine decarboxylase and S-adenosyl methionine decarboxylase activities and this transcription occurs at both temperatures early in G(,1). The synthesis of thymidine kinase messenger RNA is also required before induction of this enzyme can occur. At 34(DEGREES)C, the production of this messenger RNA occurs immediately before the enzyme is induced while at 40.8(DEGREES)C, no thymidine kinase messenger RNA is made. The decrease in ornithine decarboxylase activity, therefore, appears to be due to some alteration at the posttranscriptional level, while the block of thymidine kinase induction appears to be at the level of transcription. The G(,1) arrest at 40.8(DEGREES)C is not the result of the decreased ornithine decarboxylase levels. The low levels of enzyme appear to produce enough putrescine such that the rest of the polyamine pathway can operate normally. Furthermore, addition of exogenous polyamines to the growth medium does not alleviate the cell cycle arrest seen at this temperature. The final section of this thesis describes attempts that were made to purify ornithine decarboxylase from the cultured cells. The enzyme is quite unstable after the final step of the purification, for unless a carrier protein is added to the collected fractions it loses activity within 24 hours. Presently, this system is not feasible for use in purifying large quantities of purified enzyme since the yield from each experiment is quite low. Further work, aimed at improving the yield of ornithine decarboxylase, is currently an ongoing project in this laboratory.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Biology. $3 599573
655 7 $a Electronic books. $2 local $3 554714
690 $a 0306
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a University of California, San Diego. $3 1187935
773 0 $t Dissertations Abstracts International $g 41-07B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8018793 $z click for full text (PQDT)