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Dramatic age-related changes in nuclear and genome copy number in the nematode Caenorhabditis elegans.

Golden TR, Beckman KB, Lee AH, Dudek N, Hubbard A, Samper E, Melov S - Aging Cell (2007)

Bottom Line: We report both systematic loss of nuclei or nuclear DNA, as well as dramatic age-related changes in nuclear genome copy number.These changes are delayed or attenuated in long-lived daf-2 mutants.We propose that these changes are important pathobiological characteristics of aging nematodes.

View Article: PubMed Central - PubMed

Affiliation: Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945, USA.

ABSTRACT
The nematode Caenorhabditis elegans has become one of the most widely used model systems for the study of aging, yet very little is known about how C. elegans age. The development of the worm, from egg to young adult has been completely mapped at the cellular level, but such detailed studies have not been extended throughout the adult lifespan. Numerous single gene mutations, drug treatments and environmental manipulations have been found to extend worm lifespan. To interpret the mechanism of action of such aging interventions, studies to characterize normal worm aging, similar to those used to study worm development are necessary. We have used 4',6'-diamidino-2-phenylindole hydrochloride staining and quantitative polymerase chain reaction to investigate the integrity of nuclei and quantify the nuclear genome copy number of C. elegans with age. We report both systematic loss of nuclei or nuclear DNA, as well as dramatic age-related changes in nuclear genome copy number. These changes are delayed or attenuated in long-lived daf-2 mutants. We propose that these changes are important pathobiological characteristics of aging nematodes.

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Accumulation of masses of nucleic acid in aged, wild-type N2 nematodes. (a) 4 days old. (b) 14 days old. (c) 19 days old. Worms were fixed and stained with DAPI to detect DNA. Note the mitotic nuclei at the distal tips of the gonad at each age (arrows). In the 4-day-old individual, nuclei of the developing embryos are visible. In the 14- and 19-day-old individuals, no embryos are present, and the space is filled with amorphous, tumor-like masses (arrowheads). Masses are defined as brightly staining structures not attributable to nuclei of the adult or embryos. These individuals are representative of 10 individuals of each age studied.
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fig02: Accumulation of masses of nucleic acid in aged, wild-type N2 nematodes. (a) 4 days old. (b) 14 days old. (c) 19 days old. Worms were fixed and stained with DAPI to detect DNA. Note the mitotic nuclei at the distal tips of the gonad at each age (arrows). In the 4-day-old individual, nuclei of the developing embryos are visible. In the 14- and 19-day-old individuals, no embryos are present, and the space is filled with amorphous, tumor-like masses (arrowheads). Masses are defined as brightly staining structures not attributable to nuclei of the adult or embryos. These individuals are representative of 10 individuals of each age studied.

Mentions: The second age-related phenomenon detected via DAPI staining is a massive accumulation of DAPI-stained material in the mid-section of wild-type nematodes of middle age (Fig. 2). These masses of DNA grew to essentially fill the body cavity of the nematode (Fig. 2 and Supplemental movie). Long-lived daf-2(e1368) nematodes (Supplementary Fig. S1) did accumulate DAPI-reactive masses, but to a lesser extent than N2 and much delayed when compared to N2. The long-lived strain daf-2(e1370) (Fig. 3) rarely accumulated masses. BrdU was incorporated into the region of the masses in 11-day-old N2 nematodes, but not 9-day-old N2 nematodes (Fig. 4), indicating that their generation requires active DNA synthesis that begins after 9 days of age. The acid treatment necessary for immunostaining with the anti-BrdU antibody interfered with DAPI staining of DNA, preventing costaining of the masses for BrdU and with DAPI.


Dramatic age-related changes in nuclear and genome copy number in the nematode Caenorhabditis elegans.

Golden TR, Beckman KB, Lee AH, Dudek N, Hubbard A, Samper E, Melov S - Aging Cell (2007)

Accumulation of masses of nucleic acid in aged, wild-type N2 nematodes. (a) 4 days old. (b) 14 days old. (c) 19 days old. Worms were fixed and stained with DAPI to detect DNA. Note the mitotic nuclei at the distal tips of the gonad at each age (arrows). In the 4-day-old individual, nuclei of the developing embryos are visible. In the 14- and 19-day-old individuals, no embryos are present, and the space is filled with amorphous, tumor-like masses (arrowheads). Masses are defined as brightly staining structures not attributable to nuclei of the adult or embryos. These individuals are representative of 10 individuals of each age studied.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2049047&req=5

fig02: Accumulation of masses of nucleic acid in aged, wild-type N2 nematodes. (a) 4 days old. (b) 14 days old. (c) 19 days old. Worms were fixed and stained with DAPI to detect DNA. Note the mitotic nuclei at the distal tips of the gonad at each age (arrows). In the 4-day-old individual, nuclei of the developing embryos are visible. In the 14- and 19-day-old individuals, no embryos are present, and the space is filled with amorphous, tumor-like masses (arrowheads). Masses are defined as brightly staining structures not attributable to nuclei of the adult or embryos. These individuals are representative of 10 individuals of each age studied.
Mentions: The second age-related phenomenon detected via DAPI staining is a massive accumulation of DAPI-stained material in the mid-section of wild-type nematodes of middle age (Fig. 2). These masses of DNA grew to essentially fill the body cavity of the nematode (Fig. 2 and Supplemental movie). Long-lived daf-2(e1368) nematodes (Supplementary Fig. S1) did accumulate DAPI-reactive masses, but to a lesser extent than N2 and much delayed when compared to N2. The long-lived strain daf-2(e1370) (Fig. 3) rarely accumulated masses. BrdU was incorporated into the region of the masses in 11-day-old N2 nematodes, but not 9-day-old N2 nematodes (Fig. 4), indicating that their generation requires active DNA synthesis that begins after 9 days of age. The acid treatment necessary for immunostaining with the anti-BrdU antibody interfered with DAPI staining of DNA, preventing costaining of the masses for BrdU and with DAPI.

Bottom Line: We report both systematic loss of nuclei or nuclear DNA, as well as dramatic age-related changes in nuclear genome copy number.These changes are delayed or attenuated in long-lived daf-2 mutants.We propose that these changes are important pathobiological characteristics of aging nematodes.

View Article: PubMed Central - PubMed

Affiliation: Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945, USA.

ABSTRACT
The nematode Caenorhabditis elegans has become one of the most widely used model systems for the study of aging, yet very little is known about how C. elegans age. The development of the worm, from egg to young adult has been completely mapped at the cellular level, but such detailed studies have not been extended throughout the adult lifespan. Numerous single gene mutations, drug treatments and environmental manipulations have been found to extend worm lifespan. To interpret the mechanism of action of such aging interventions, studies to characterize normal worm aging, similar to those used to study worm development are necessary. We have used 4',6'-diamidino-2-phenylindole hydrochloride staining and quantitative polymerase chain reaction to investigate the integrity of nuclei and quantify the nuclear genome copy number of C. elegans with age. We report both systematic loss of nuclei or nuclear DNA, as well as dramatic age-related changes in nuclear genome copy number. These changes are delayed or attenuated in long-lived daf-2 mutants. We propose that these changes are important pathobiological characteristics of aging nematodes.

Show MeSH