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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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Loss of hypodermal nuclei with age from the tails of N2 and daf-2 nematodes. (a) Tails of N2 nematodes, stained with DAPI. Worms were picked from a synchronized population initiated with a timed lay. The date of the lay is counted as day 0. Images were examined and scored as to how many nuclei were visible in the tail. In the majority of aged nematodes, the nuclei corresponding to hypodermal nuclei H9 and H10 are lost [(arrowheads, quantified in (b) and (c)]. Although not quantified, we noted the appearance of nuclei with a fragmented or condensed appearance with age (arrows, bottom panel) (top: 4 days old, middle: 14 days old, bottom: 19 days old). (b) Count of nuclei visible in the tails of individual N2 nematodes. (c) Count of nuclei visible in the tails of individual daf-2(e1368) nematodes. Ten individuals were counted per group, except 19-day-old N2 for which nine were counted.
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fig01: Loss of hypodermal nuclei with age from the tails of N2 and daf-2 nematodes. (a) Tails of N2 nematodes, stained with DAPI. Worms were picked from a synchronized population initiated with a timed lay. The date of the lay is counted as day 0. Images were examined and scored as to how many nuclei were visible in the tail. In the majority of aged nematodes, the nuclei corresponding to hypodermal nuclei H9 and H10 are lost [(arrowheads, quantified in (b) and (c)]. Although not quantified, we noted the appearance of nuclei with a fragmented or condensed appearance with age (arrows, bottom panel) (top: 4 days old, middle: 14 days old, bottom: 19 days old). (b) Count of nuclei visible in the tails of individual N2 nematodes. (c) Count of nuclei visible in the tails of individual daf-2(e1368) nematodes. Ten individuals were counted per group, except 19-day-old N2 for which nine were counted.

Mentions: We observed nuclei in aging C. elegans by staining with the DNA-binding dye DAPI. The nematode's optical transparency allows the visualization of every nuclei in the intact worm. Two dramatic age-related phenomena were revealed by DAPI staining. First, DAPI staining of three nuclei in the tail is lost with age (Fig. 1a,b). These likely are the nuclei of the H9 and H10 hypodermal cells (H10 being binucleate), based on comparison to published maps of hypodermal nuclei (Altun & Hall, 2005). These nuclei may be lost, or alternatively, the nuclear DNA may be degraded or damaged to such an extent that DAPI staining is lost. This nuclear loss also occurred in long-lived daf-2(e1368) and daf-2(e1370) nematodes, but was delayed relative to the occurrence in N2 (Fig. 1c and data not shown).


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)

Loss of hypodermal nuclei with age from the tails of N2 and daf-2 nematodes. (a) Tails of N2 nematodes, stained with DAPI. Worms were picked from a synchronized population initiated with a timed lay. The date of the lay is counted as day 0. Images were examined and scored as to how many nuclei were visible in the tail. In the majority of aged nematodes, the nuclei corresponding to hypodermal nuclei H9 and H10 are lost [(arrowheads, quantified in (b) and (c)]. Although not quantified, we noted the appearance of nuclei with a fragmented or condensed appearance with age (arrows, bottom panel) (top: 4 days old, middle: 14 days old, bottom: 19 days old). (b) Count of nuclei visible in the tails of individual N2 nematodes. (c) Count of nuclei visible in the tails of individual daf-2(e1368) nematodes. Ten individuals were counted per group, except 19-day-old N2 for which nine were counted.
© Copyright Policy
Related In: Results  -  Collection

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fig01: Loss of hypodermal nuclei with age from the tails of N2 and daf-2 nematodes. (a) Tails of N2 nematodes, stained with DAPI. Worms were picked from a synchronized population initiated with a timed lay. The date of the lay is counted as day 0. Images were examined and scored as to how many nuclei were visible in the tail. In the majority of aged nematodes, the nuclei corresponding to hypodermal nuclei H9 and H10 are lost [(arrowheads, quantified in (b) and (c)]. Although not quantified, we noted the appearance of nuclei with a fragmented or condensed appearance with age (arrows, bottom panel) (top: 4 days old, middle: 14 days old, bottom: 19 days old). (b) Count of nuclei visible in the tails of individual N2 nematodes. (c) Count of nuclei visible in the tails of individual daf-2(e1368) nematodes. Ten individuals were counted per group, except 19-day-old N2 for which nine were counted.
Mentions: We observed nuclei in aging C. elegans by staining with the DNA-binding dye DAPI. The nematode's optical transparency allows the visualization of every nuclei in the intact worm. Two dramatic age-related phenomena were revealed by DAPI staining. First, DAPI staining of three nuclei in the tail is lost with age (Fig. 1a,b). These likely are the nuclei of the H9 and H10 hypodermal cells (H10 being binucleate), based on comparison to published maps of hypodermal nuclei (Altun & Hall, 2005). These nuclei may be lost, or alternatively, the nuclear DNA may be degraded or damaged to such an extent that DAPI staining is lost. This nuclear loss also occurred in long-lived daf-2(e1368) and daf-2(e1370) nematodes, but was delayed relative to the occurrence in N2 (Fig. 1c and data not shown).

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