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DNA replication during sporulation in Myxococcus xanthus fruiting bodies.

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Title: DNA replication during sporulation in Myxococcus xanthus fruiting bodies.
Authors: Linfong Tzeng1, Singer, Mitchell1 mhsinger@ucdavis.edu
Source: Proceedings of the National Academy of Sciences of the United States of America. 10/4/2005, Vol. 102 Issue 40, p14428-14433. 6p.
Subjects: DNA replication, DNA synthesis, Myxococcus xanthus, Flow cytometry, Cytological techniques, Fluorescence microscopy
Abstract: During the developmental process of the Gram-negative soil bacterium Myxococcus xanthus, vegetatively growing rod cells differentiate to ultimately become metabolically quiescent and environ- mentally resistant myxospores encased within fruiting bodies. This program, initiated by nutrient deprivation, is propagated by both cell-autonomous and cell-nonautonomous signals. Our goal was to determine whether M. xanthus, like many other developmental systems, uses cell-cycle cues to regulate and control its developmental program. To address this question, the DNA replication cycle was used as a marker to monitor progression through the cell cycle in vegetative, stationary, and developing M. xanthus populations. Using flow cytometry, quantitative fluorescence micros-copy, and FISH to establish the chromosome copy number of myxospores, it was determined that vegetatively growing cells contain one to two copies of the genome, but upon entry into stationary phase, the chromosome copy number drops to a single copy. Of particular interest, fruiting body-derived myxospores contain a specific two-chromosome DNA complement with both origin and terminus regions localized to the periphery of the myxospore. We speculate that this duplication of genetic information in the myxospore would help assure viability during germination by providing a second copy of each gene. The results of this study imply that not only is DNA replication tightly regulated during the developmental process of M. xanthus, but that there are also regulatory mechanisms to ensure that all myxospores acquire two copies of the chromosome. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:During the developmental process of the Gram-negative soil bacterium Myxococcus xanthus, vegetatively growing rod cells differentiate to ultimately become metabolically quiescent and environ- mentally resistant myxospores encased within fruiting bodies. This program, initiated by nutrient deprivation, is propagated by both cell-autonomous and cell-nonautonomous signals. Our goal was to determine whether M. xanthus, like many other developmental systems, uses cell-cycle cues to regulate and control its developmental program. To address this question, the DNA replication cycle was used as a marker to monitor progression through the cell cycle in vegetative, stationary, and developing M. xanthus populations. Using flow cytometry, quantitative fluorescence micros-copy, and FISH to establish the chromosome copy number of myxospores, it was determined that vegetatively growing cells contain one to two copies of the genome, but upon entry into stationary phase, the chromosome copy number drops to a single copy. Of particular interest, fruiting body-derived myxospores contain a specific two-chromosome DNA complement with both origin and terminus regions localized to the periphery of the myxospore. We speculate that this duplication of genetic information in the myxospore would help assure viability during germination by providing a second copy of each gene. The results of this study imply that not only is DNA replication tightly regulated during the developmental process of M. xanthus, but that there are also regulatory mechanisms to ensure that all myxospores acquire two copies of the chromosome. [ABSTRACT FROM AUTHOR]
ISSN:00278424
DOI:10.1073/pnas.0506969102