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Rec-8 dimorphism affects longevity, stress resistance and X-chromosome nondisjunction in C. elegans, and replicative lifespan in S. cerevisiae.

Ayyadevara S, Tazearslan C, Alla R, Jiang JC, Jazwinski SM, Shmookler Reis RJ - Front Genet (2014)

Bottom Line: A single gene in this interval is now shown to modulate all lsq4-associated traits.Full-genome analysis of transcript levels indicates that lsq4 contains a dimorphic gene governing the expression of many sperm-specific genes, suggesting an effect on spermatogenesis.Fourteen "dual-candidate" genes, implicated by both position and expression, were tested for RNA-interference effects on QTL-linked traits.

View Article: PubMed Central - PubMed

Affiliation: Central Arkansas Veterans Healthcare System, VA Medical Center Little Rock, AR, USA ; Department of Geriatrics, University of Arkansas for Medical Sciences Little Rock, AR, USA.

ABSTRACT
A quantitative trait locus (QTL) in the nematode C. elegans, "lsq4," was recently implicated by mapping longevity genes. QTLs for lifespan and three stress-resistance traits coincided within a span of <300 kbp, later narrowed to <200 kbp. A single gene in this interval is now shown to modulate all lsq4-associated traits. Full-genome analysis of transcript levels indicates that lsq4 contains a dimorphic gene governing the expression of many sperm-specific genes, suggesting an effect on spermatogenesis. Quantitative analysis of allele-specific transcripts encoded within the lsq4 interval revealed significant, 2- to 15-fold expression differences for 10 of 33 genes. Fourteen "dual-candidate" genes, implicated by both position and expression, were tested for RNA-interference effects on QTL-linked traits. In a strain carrying the shorter-lived allele, knockdown of rec-8 (encoding a meiotic cohesin) reduced its transcripts 4-fold, to a level similar to the longer-lived strain, while extending lifespan 25-26%, whether begun before fertilization or at maturity. The short-lived lsq4 allele also conferred sensitivity to oxidative and thermal stresses, and lower male frequency (reflecting X-chromosome non-disjunction), traits reversed uniquely by rec-8 knockdown. A strain bearing the longer-lived lsq4 allele, differing from the short-lived strain at <0.3% of its genome, derived no lifespan or stress-survival benefit from rec-8 knockdown. We consider two possible explanations: high rec-8 expression may include increased "leaky" expression in mitotic cells, leading to deleterious destabilization of somatic genomes; or REC-8 may act entirely in germ-line meiotic cells to reduce aberrations such as non-disjunction, thereby blunting a stress-resistance response mediated by innate immunity. Replicative lifespan was extended 20% in haploid S. cerevisiae (BY4741) by deletion of REC8, orthologous to nematode rec-8, implying that REC8 disruption of mitotic-cell survival is widespread, exemplifying antagonistic pleiotropy (opposing effects on lifespan vs. reproduction), and/or balancing selection wherein genomic disruption increases genetic variation under harsh conditions.

No MeSH data available.


Related in: MedlinePlus

Deletion of REC8 increases replicative lifespan in a long-lived yeast strain that limits transcripts of this gene. (A) Replicative lifespan was measured for the BY4741.ch strain and 5 independent deletion mutations, all assessed as haploids, in two experiments. In the first experiment, strain YPK9 and two REC8 deletion mutants were also assessed. Means lifespans (in generations) are shown, with the significance of differences from the parental control strain indicated by asterisks. Four of the five BY4741 deletion clones were significantly longer lived than the within-experiment control, by P < 0.05; the combined significance of the 5 clonal life extensions was 4 × 10−8. (B) The group means and standard deviations are shown for the two genotype groups, treating each mean lifespan of a control or rec8Δ clone as a single point. Even by this conservative approach, the 5 rec8Δ clones differed from the two control assays at P = 0.001. (C) Transcript levels were assessed by quantitative real-time polymerase chain reaction (RT-PCR) for REC8 relative to ACT1 (actin), as described in Materials and Methods. Results are shown for triplicate cultures of the wild-type strains, with error bars indicating standard deviations. *P < 0.05; **P < 0.01; ***P = 0.001.
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Figure 4: Deletion of REC8 increases replicative lifespan in a long-lived yeast strain that limits transcripts of this gene. (A) Replicative lifespan was measured for the BY4741.ch strain and 5 independent deletion mutations, all assessed as haploids, in two experiments. In the first experiment, strain YPK9 and two REC8 deletion mutants were also assessed. Means lifespans (in generations) are shown, with the significance of differences from the parental control strain indicated by asterisks. Four of the five BY4741 deletion clones were significantly longer lived than the within-experiment control, by P < 0.05; the combined significance of the 5 clonal life extensions was 4 × 10−8. (B) The group means and standard deviations are shown for the two genotype groups, treating each mean lifespan of a control or rec8Δ clone as a single point. Even by this conservative approach, the 5 rec8Δ clones differed from the two control assays at P = 0.001. (C) Transcript levels were assessed by quantitative real-time polymerase chain reaction (RT-PCR) for REC8 relative to ACT1 (actin), as described in Materials and Methods. Results are shown for triplicate cultures of the wild-type strains, with error bars indicating standard deviations. *P < 0.05; **P < 0.01; ***P = 0.001.

Mentions: The Rec8p cohesin-complex proteins of fission and budding yeast are functionally analogous to the nematode REC-8 protein, and are considered to be its orthologs (http://www.wormbase.org/, Pasierbek et al., 2001). We tested the effect of REC8 deletion on the number of mitotic progeny produced per mother cell, in the budding yeast Saccharomyces cerevisiae. This assay, performed as described previously (Jiang et al., 2000), was initially conducted for both the long-lived strain BY4741 (mean lifespan 29–30 bud generations) and a short-lived strain, YPK9 (20–21 bud generations). As summarized in Figure 4, replicative lifespan increased significantly in 4 of 5 of BY4741 rec8Δ clones, whereas it declined slightly but insignificantly in two YPK9 rec8Δ clones. The BY4741 rec8Δ clones increased in mean number of progeny, relative to their within-experiment controls, from 30.2 to 36.6 (21%, P < 0.03) and 34.4 (14%, not significant) in the first experiment. In a second experiment, 3 BY4741 rec8Δ clones gained 20, 20, and 25% in replicative potential (P < 0.05, 0.03, and 0.01 respectively). Combining the data for all five clones relative to their respective controls, the longevity extension upon deleting the REC8 gene was 20 ± 4% (SD) with an overall significance of P < 5 × 10−8. We also calculated the significance (Figure 4B) by a simple t-test comparison treating each mean value as a single data point, which resulted in a more conservative P-value of 0.001. Because strain YPK9 differed markedly from BY4741, we inquired whether this might relate to the relative abundance of REC8 transcripts in the two haploid strains (which undergo mitosis but not meiosis). REC8 expression was 20-fold greater in YPK9 (Figure 4C), suggesting that this strain must not be under strong selection against harmful effects of inappropriate Rec8p expression in mitotic cells.


Rec-8 dimorphism affects longevity, stress resistance and X-chromosome nondisjunction in C. elegans, and replicative lifespan in S. cerevisiae.

Ayyadevara S, Tazearslan C, Alla R, Jiang JC, Jazwinski SM, Shmookler Reis RJ - Front Genet (2014)

Deletion of REC8 increases replicative lifespan in a long-lived yeast strain that limits transcripts of this gene. (A) Replicative lifespan was measured for the BY4741.ch strain and 5 independent deletion mutations, all assessed as haploids, in two experiments. In the first experiment, strain YPK9 and two REC8 deletion mutants were also assessed. Means lifespans (in generations) are shown, with the significance of differences from the parental control strain indicated by asterisks. Four of the five BY4741 deletion clones were significantly longer lived than the within-experiment control, by P < 0.05; the combined significance of the 5 clonal life extensions was 4 × 10−8. (B) The group means and standard deviations are shown for the two genotype groups, treating each mean lifespan of a control or rec8Δ clone as a single point. Even by this conservative approach, the 5 rec8Δ clones differed from the two control assays at P = 0.001. (C) Transcript levels were assessed by quantitative real-time polymerase chain reaction (RT-PCR) for REC8 relative to ACT1 (actin), as described in Materials and Methods. Results are shown for triplicate cultures of the wild-type strains, with error bars indicating standard deviations. *P < 0.05; **P < 0.01; ***P = 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4120681&req=5

Figure 4: Deletion of REC8 increases replicative lifespan in a long-lived yeast strain that limits transcripts of this gene. (A) Replicative lifespan was measured for the BY4741.ch strain and 5 independent deletion mutations, all assessed as haploids, in two experiments. In the first experiment, strain YPK9 and two REC8 deletion mutants were also assessed. Means lifespans (in generations) are shown, with the significance of differences from the parental control strain indicated by asterisks. Four of the five BY4741 deletion clones were significantly longer lived than the within-experiment control, by P < 0.05; the combined significance of the 5 clonal life extensions was 4 × 10−8. (B) The group means and standard deviations are shown for the two genotype groups, treating each mean lifespan of a control or rec8Δ clone as a single point. Even by this conservative approach, the 5 rec8Δ clones differed from the two control assays at P = 0.001. (C) Transcript levels were assessed by quantitative real-time polymerase chain reaction (RT-PCR) for REC8 relative to ACT1 (actin), as described in Materials and Methods. Results are shown for triplicate cultures of the wild-type strains, with error bars indicating standard deviations. *P < 0.05; **P < 0.01; ***P = 0.001.
Mentions: The Rec8p cohesin-complex proteins of fission and budding yeast are functionally analogous to the nematode REC-8 protein, and are considered to be its orthologs (http://www.wormbase.org/, Pasierbek et al., 2001). We tested the effect of REC8 deletion on the number of mitotic progeny produced per mother cell, in the budding yeast Saccharomyces cerevisiae. This assay, performed as described previously (Jiang et al., 2000), was initially conducted for both the long-lived strain BY4741 (mean lifespan 29–30 bud generations) and a short-lived strain, YPK9 (20–21 bud generations). As summarized in Figure 4, replicative lifespan increased significantly in 4 of 5 of BY4741 rec8Δ clones, whereas it declined slightly but insignificantly in two YPK9 rec8Δ clones. The BY4741 rec8Δ clones increased in mean number of progeny, relative to their within-experiment controls, from 30.2 to 36.6 (21%, P < 0.03) and 34.4 (14%, not significant) in the first experiment. In a second experiment, 3 BY4741 rec8Δ clones gained 20, 20, and 25% in replicative potential (P < 0.05, 0.03, and 0.01 respectively). Combining the data for all five clones relative to their respective controls, the longevity extension upon deleting the REC8 gene was 20 ± 4% (SD) with an overall significance of P < 5 × 10−8. We also calculated the significance (Figure 4B) by a simple t-test comparison treating each mean value as a single data point, which resulted in a more conservative P-value of 0.001. Because strain YPK9 differed markedly from BY4741, we inquired whether this might relate to the relative abundance of REC8 transcripts in the two haploid strains (which undergo mitosis but not meiosis). REC8 expression was 20-fold greater in YPK9 (Figure 4C), suggesting that this strain must not be under strong selection against harmful effects of inappropriate Rec8p expression in mitotic cells.

Bottom Line: A single gene in this interval is now shown to modulate all lsq4-associated traits.Full-genome analysis of transcript levels indicates that lsq4 contains a dimorphic gene governing the expression of many sperm-specific genes, suggesting an effect on spermatogenesis.Fourteen "dual-candidate" genes, implicated by both position and expression, were tested for RNA-interference effects on QTL-linked traits.

View Article: PubMed Central - PubMed

Affiliation: Central Arkansas Veterans Healthcare System, VA Medical Center Little Rock, AR, USA ; Department of Geriatrics, University of Arkansas for Medical Sciences Little Rock, AR, USA.

ABSTRACT
A quantitative trait locus (QTL) in the nematode C. elegans, "lsq4," was recently implicated by mapping longevity genes. QTLs for lifespan and three stress-resistance traits coincided within a span of <300 kbp, later narrowed to <200 kbp. A single gene in this interval is now shown to modulate all lsq4-associated traits. Full-genome analysis of transcript levels indicates that lsq4 contains a dimorphic gene governing the expression of many sperm-specific genes, suggesting an effect on spermatogenesis. Quantitative analysis of allele-specific transcripts encoded within the lsq4 interval revealed significant, 2- to 15-fold expression differences for 10 of 33 genes. Fourteen "dual-candidate" genes, implicated by both position and expression, were tested for RNA-interference effects on QTL-linked traits. In a strain carrying the shorter-lived allele, knockdown of rec-8 (encoding a meiotic cohesin) reduced its transcripts 4-fold, to a level similar to the longer-lived strain, while extending lifespan 25-26%, whether begun before fertilization or at maturity. The short-lived lsq4 allele also conferred sensitivity to oxidative and thermal stresses, and lower male frequency (reflecting X-chromosome non-disjunction), traits reversed uniquely by rec-8 knockdown. A strain bearing the longer-lived lsq4 allele, differing from the short-lived strain at <0.3% of its genome, derived no lifespan or stress-survival benefit from rec-8 knockdown. We consider two possible explanations: high rec-8 expression may include increased "leaky" expression in mitotic cells, leading to deleterious destabilization of somatic genomes; or REC-8 may act entirely in germ-line meiotic cells to reduce aberrations such as non-disjunction, thereby blunting a stress-resistance response mediated by innate immunity. Replicative lifespan was extended 20% in haploid S. cerevisiae (BY4741) by deletion of REC8, orthologous to nematode rec-8, implying that REC8 disruption of mitotic-cell survival is widespread, exemplifying antagonistic pleiotropy (opposing effects on lifespan vs. reproduction), and/or balancing selection wherein genomic disruption increases genetic variation under harsh conditions.

No MeSH data available.


Related in: MedlinePlus