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Gene expression disruptions of organism versus organ in Drosophila species hybrids.

Catron DJ, Noor MA - PLoS ONE (2008)

Bottom Line: However, these studies often examined whole bodies rather than testes or had limited replication using less-sensitive but global techniques.Here, we use a new RNA isolation technique to re-examine hybrid gene expression disruptions in both testes and whole bodies from single Drosophila males by real-time quantitative RT-PCR.Although the number of transcripts surveyed is limited, these results provide some support for a previous hypothesis that the spermatogenesis pathway in these sterile hybrids may be disrupted sometime after the expression of the early meiotic arrest genes.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Duke University, Durham, North Carolina, United States of America.

ABSTRACT
Hybrid dysfunctions, such as sterility, may result in part from disruptions in the regulation of gene expression. Studies of hybrids within the Drosophila simulans clade have reported genes expressed above or below the expression observed in their parent species, and such misexpression is associated with male sterility in multigenerational backcross hybrids. However, these studies often examined whole bodies rather than testes or had limited replication using less-sensitive but global techniques. Here, we use a new RNA isolation technique to re-examine hybrid gene expression disruptions in both testes and whole bodies from single Drosophila males by real-time quantitative RT-PCR. We find two early-spermatogenesis transcripts are underexpressed in hybrid whole-bodies but not in assays of testes alone, while two late-spermatogenesis transcripts seem to be underexpressed in both whole-bodies and testes alone. Although the number of transcripts surveyed is limited, these results provide some support for a previous hypothesis that the spermatogenesis pathway in these sterile hybrids may be disrupted sometime after the expression of the early meiotic arrest genes.

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Drosophila spermatogenesis regulatory pathway [adapted from 17], [18].
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pone-0003009-g001: Drosophila spermatogenesis regulatory pathway [adapted from 17], [18].

Mentions: Disruptions in gene expression have been examined extensively in hybrids of the genus Drosophila [e.g.9], [10], and particularly within the D. simulans clade (D. simulans, D. mauritiana, D. sechellia). Recent studies have used microarrays to examine disruptions in gene expression in male hybrids of D. simulans clade species [11]–[13]. All three studies found many genes severely underexpressed in the hybrids relative to the pure species, and these genes were disproportionately associated with spermatogenesis or other male-specific phenotypes. Michalak and Noor [14] further found that sterility and underexpression of five transcripts were strongly correlated in fifth generation backcross hybrids of D. simulans and D. mauritiana, and a recent study found that one of these transcripts appears to be directly involved in incompatibilities leading to hybrid sterility [15]. Thus, it is possible that misexpression of male-fertility-essential genes involved in spermatogenesis caused sterility in these hybrids. Underexpressed genes also appear to be more rapidly evolving than genes expressed normally in hybrids [16]. Finally, Moehring et al. [13] overlaid their misexpression results onto part of a known spermatogenesis pathway for D. melanogaster [see Figure 1, adapted from 17,18] and found many late-stage downstream loci exhibiting misexpression (e.g., don juan, gonadal, Mst84D, Mst98Ca, Mst98Cb, Mst87D), whereas relatively few early-stage loci were misexpressed. This finding may suggest that the spermatogenesis regulatory pathway could be disrupted at a particular stage.


Gene expression disruptions of organism versus organ in Drosophila species hybrids.

Catron DJ, Noor MA - PLoS ONE (2008)

Drosophila spermatogenesis regulatory pathway [adapted from 17], [18].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2500191&req=5

pone-0003009-g001: Drosophila spermatogenesis regulatory pathway [adapted from 17], [18].
Mentions: Disruptions in gene expression have been examined extensively in hybrids of the genus Drosophila [e.g.9], [10], and particularly within the D. simulans clade (D. simulans, D. mauritiana, D. sechellia). Recent studies have used microarrays to examine disruptions in gene expression in male hybrids of D. simulans clade species [11]–[13]. All three studies found many genes severely underexpressed in the hybrids relative to the pure species, and these genes were disproportionately associated with spermatogenesis or other male-specific phenotypes. Michalak and Noor [14] further found that sterility and underexpression of five transcripts were strongly correlated in fifth generation backcross hybrids of D. simulans and D. mauritiana, and a recent study found that one of these transcripts appears to be directly involved in incompatibilities leading to hybrid sterility [15]. Thus, it is possible that misexpression of male-fertility-essential genes involved in spermatogenesis caused sterility in these hybrids. Underexpressed genes also appear to be more rapidly evolving than genes expressed normally in hybrids [16]. Finally, Moehring et al. [13] overlaid their misexpression results onto part of a known spermatogenesis pathway for D. melanogaster [see Figure 1, adapted from 17,18] and found many late-stage downstream loci exhibiting misexpression (e.g., don juan, gonadal, Mst84D, Mst98Ca, Mst98Cb, Mst87D), whereas relatively few early-stage loci were misexpressed. This finding may suggest that the spermatogenesis regulatory pathway could be disrupted at a particular stage.

Bottom Line: However, these studies often examined whole bodies rather than testes or had limited replication using less-sensitive but global techniques.Here, we use a new RNA isolation technique to re-examine hybrid gene expression disruptions in both testes and whole bodies from single Drosophila males by real-time quantitative RT-PCR.Although the number of transcripts surveyed is limited, these results provide some support for a previous hypothesis that the spermatogenesis pathway in these sterile hybrids may be disrupted sometime after the expression of the early meiotic arrest genes.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Duke University, Durham, North Carolina, United States of America.

ABSTRACT
Hybrid dysfunctions, such as sterility, may result in part from disruptions in the regulation of gene expression. Studies of hybrids within the Drosophila simulans clade have reported genes expressed above or below the expression observed in their parent species, and such misexpression is associated with male sterility in multigenerational backcross hybrids. However, these studies often examined whole bodies rather than testes or had limited replication using less-sensitive but global techniques. Here, we use a new RNA isolation technique to re-examine hybrid gene expression disruptions in both testes and whole bodies from single Drosophila males by real-time quantitative RT-PCR. We find two early-spermatogenesis transcripts are underexpressed in hybrid whole-bodies but not in assays of testes alone, while two late-spermatogenesis transcripts seem to be underexpressed in both whole-bodies and testes alone. Although the number of transcripts surveyed is limited, these results provide some support for a previous hypothesis that the spermatogenesis pathway in these sterile hybrids may be disrupted sometime after the expression of the early meiotic arrest genes.

Show MeSH
Related in: MedlinePlus