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Impact of gut microbiota on the fly's germ line.

Elgart M, Stern S, Salton O, Gnainsky Y, Heifetz Y, Soen Y - Nat Commun (2016)

Bottom Line: Unlike vertically transmitted endosymbionts, which have broad effects on their host's germ line, the extracellular gut microbiota is transmitted horizontally and is not known to influence the germ line.We further show that the main impact on oogenesis is linked to the lack of gut Acetobacter species, and we identify the Drosophila Aldehyde dehydrogenase (Aldh) gene as an apparent mediator of repressed oogenesis in Acetobacter-depleted flies.The finding of interactions between the gut microbiota and the germ line has implications for reproduction, developmental robustness and adaptation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.

ABSTRACT
Unlike vertically transmitted endosymbionts, which have broad effects on their host's germ line, the extracellular gut microbiota is transmitted horizontally and is not known to influence the germ line. Here we provide evidence supporting the influence of these gut bacteria on the germ line of Drosophila melanogaster. Removal of the gut bacteria represses oogenesis, expedites maternal-to-zygotic-transition in the offspring and unmasks hidden phenotypic variation in mutants. We further show that the main impact on oogenesis is linked to the lack of gut Acetobacter species, and we identify the Drosophila Aldehyde dehydrogenase (Aldh) gene as an apparent mediator of repressed oogenesis in Acetobacter-depleted flies. The finding of interactions between the gut microbiota and the germ line has implications for reproduction, developmental robustness and adaptation.

No MeSH data available.


Related in: MedlinePlus

Lack of Acetobacter appears to suppress oogenesis by repression of Aldh in the ovary.(a) Removal of gut bacteria by dechorionation leads to tissue specific changes of Aldh expression in the larval gut (F1 3rd instar) and in the next generation of embryos (F2, 2 h AED). Mean fold-change (qPCR-based)±s.e. n=3, *** P<0.001 (Student's t-test). (b) RNA-seq measurements of changes in representative genes within the Aldh network (left), compiled using the STRING protein–protein interaction database. Blue labels designate genes that are downregulated in 2 h AED embryos of bacterial-depleted flies versus control. Mean fold-change±s.e. based on duplicates for three lines (six samples per condition). **P<0.01, ***P<0.001 (Wald Statistics, DESeq package). (c) qPCR-based changes in the levels of Aldh network genes in 40 min and 2 h AED embryos of bacterial-depleted flies relative to embryos of untreated flies at the respective time. Mean fold-change±s.e. n=3, *P<0.05, ** P<0.01 (Student's t-test). (d) Enzymatic activity of Aldh in the gut of 3rd instar larvae and ovary of 6-day-old adult females. Shown are data for intact females ('Control') and females that were developed from dechorionated eggs ('Dechor.'), with and without prior re-introduction of Actetobacter or Lactobacillus species. Mean fold-change versus control±s.e., n≥3, *P<0.05, **P<0.01 (Student's t-test). (e) qPCR-based changes in the levels of Aldh network genes in 2 h AED (F2) embryos of bacterial-depleted (F1) flies, with and without re-introduction of Actetobacter species in F1. Mean fold-change versus control±s.e., n≥3, *P<0.05, **P<0.01 (Student's t-test). (f) Representative images of DAPI-stained ovaries at day 6 after eclosion of untreated females ('Control') and females developed from dechorionated eggs (Dechor.), Aldh  egg ('Aldh24K ()') and wild type females in which Aldh has been inhibited by exposure to cyanamide throughout the larval and adult stage ('Cynamide'). Note the similar impact of bacterial removal and Aldh loss (or inhibition) on ovary size and the number of mature oocytes. (g) Number of oocytes per ovary and percentages of oocytes in stages 8–10 and 11–14. Data corresponds to the cases in f and to wild-type and Aldh24K  females developed after dechorionation and re-introduction of defined Acetobacter spp. (‘Dechor.+Aceto' and ‘Aldh24K+Aceto', respectively). Mean±s.e. based on three replicated experiments, each with >20 ovaries. **P<0.01 (Student's t-test). (h) Relative egg deposition by 6-day-old Aldh  females, wild type females and females that were developed from Dechorionated eggs. Mean fold-change compared to control±s.e. based on four replicated experiments, each with five vials. **P<0.01 (Student's t-test).
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f3: Lack of Acetobacter appears to suppress oogenesis by repression of Aldh in the ovary.(a) Removal of gut bacteria by dechorionation leads to tissue specific changes of Aldh expression in the larval gut (F1 3rd instar) and in the next generation of embryos (F2, 2 h AED). Mean fold-change (qPCR-based)±s.e. n=3, *** P<0.001 (Student's t-test). (b) RNA-seq measurements of changes in representative genes within the Aldh network (left), compiled using the STRING protein–protein interaction database. Blue labels designate genes that are downregulated in 2 h AED embryos of bacterial-depleted flies versus control. Mean fold-change±s.e. based on duplicates for three lines (six samples per condition). **P<0.01, ***P<0.001 (Wald Statistics, DESeq package). (c) qPCR-based changes in the levels of Aldh network genes in 40 min and 2 h AED embryos of bacterial-depleted flies relative to embryos of untreated flies at the respective time. Mean fold-change±s.e. n=3, *P<0.05, ** P<0.01 (Student's t-test). (d) Enzymatic activity of Aldh in the gut of 3rd instar larvae and ovary of 6-day-old adult females. Shown are data for intact females ('Control') and females that were developed from dechorionated eggs ('Dechor.'), with and without prior re-introduction of Actetobacter or Lactobacillus species. Mean fold-change versus control±s.e., n≥3, *P<0.05, **P<0.01 (Student's t-test). (e) qPCR-based changes in the levels of Aldh network genes in 2 h AED (F2) embryos of bacterial-depleted (F1) flies, with and without re-introduction of Actetobacter species in F1. Mean fold-change versus control±s.e., n≥3, *P<0.05, **P<0.01 (Student's t-test). (f) Representative images of DAPI-stained ovaries at day 6 after eclosion of untreated females ('Control') and females developed from dechorionated eggs (Dechor.), Aldh egg ('Aldh24K ()') and wild type females in which Aldh has been inhibited by exposure to cyanamide throughout the larval and adult stage ('Cynamide'). Note the similar impact of bacterial removal and Aldh loss (or inhibition) on ovary size and the number of mature oocytes. (g) Number of oocytes per ovary and percentages of oocytes in stages 8–10 and 11–14. Data corresponds to the cases in f and to wild-type and Aldh24K females developed after dechorionation and re-introduction of defined Acetobacter spp. (‘Dechor.+Aceto' and ‘Aldh24K+Aceto', respectively). Mean±s.e. based on three replicated experiments, each with >20 ovaries. **P<0.01 (Student's t-test). (h) Relative egg deposition by 6-day-old Aldh females, wild type females and females that were developed from Dechorionated eggs. Mean fold-change compared to control±s.e. based on four replicated experiments, each with five vials. **P<0.01 (Student's t-test).

Mentions: We have previously found that larval exposure to the aminoglycoside antibiotic, G418, leads to selective depletion of gut Acetobacter, which persists in the non-exposed offspring28. In addition to this heritable change in microbiome composition, exposure to G418 led to heritable induction of Drosophila Aldh in the larval foregut43. Since antibiotics also have bacterial-independent effects on the host tissue2728, we tested if the change in Aldh is indeed caused by Acetobacter depletion. Analysis of Aldh expression after removal of gut bacteria by egg dechorionation revealed tissue-specific effects which partly (but not fully) overlap with the effects of G418. Similarly to G418 treatment, dechorionation upregulated Aldh in the gut of 3rd-instar larvae (Fig. 3a, left). However, unlike G418, dechorionation led to downregulation of Aldh in the following generation of embryos (Fig. 3a, right). This reduction of Aldh mRNA in the embryos was accompanied by downregulation of almost all the closely related (‘Aldh network') genes that we compiled using the STRING database44 (Fig. 3b; Supplementary Fig. 4A). A smaller reduction in Aldh mRNA was also observed at 40 min AED (Fig. 3c), suggesting that this reduction is independent of the general decrease of maternal transcripts. This suggestion was further confirmed by analysis of Aldh enzymatic activity which revealed substantial reduction of Aldh activity already in the ovary of bacterial-depleted females (Fig. 3d). The reduction in Aldh activity and the subsequent downregulation of Aldh mRNA in the embryos were both abolished by re-introduction of Acetobacter species (Fig. 3d,e). These findings indicate that depletion of gut Acetobacter affects Aldh expression in a stage- and tissue-specific manner: it upregulates Aldh in the larval gut but represses Aldh in the ovary and in the early embryos of these Acetobacter-free flies.


Impact of gut microbiota on the fly's germ line.

Elgart M, Stern S, Salton O, Gnainsky Y, Heifetz Y, Soen Y - Nat Commun (2016)

Lack of Acetobacter appears to suppress oogenesis by repression of Aldh in the ovary.(a) Removal of gut bacteria by dechorionation leads to tissue specific changes of Aldh expression in the larval gut (F1 3rd instar) and in the next generation of embryos (F2, 2 h AED). Mean fold-change (qPCR-based)±s.e. n=3, *** P<0.001 (Student's t-test). (b) RNA-seq measurements of changes in representative genes within the Aldh network (left), compiled using the STRING protein–protein interaction database. Blue labels designate genes that are downregulated in 2 h AED embryos of bacterial-depleted flies versus control. Mean fold-change±s.e. based on duplicates for three lines (six samples per condition). **P<0.01, ***P<0.001 (Wald Statistics, DESeq package). (c) qPCR-based changes in the levels of Aldh network genes in 40 min and 2 h AED embryos of bacterial-depleted flies relative to embryos of untreated flies at the respective time. Mean fold-change±s.e. n=3, *P<0.05, ** P<0.01 (Student's t-test). (d) Enzymatic activity of Aldh in the gut of 3rd instar larvae and ovary of 6-day-old adult females. Shown are data for intact females ('Control') and females that were developed from dechorionated eggs ('Dechor.'), with and without prior re-introduction of Actetobacter or Lactobacillus species. Mean fold-change versus control±s.e., n≥3, *P<0.05, **P<0.01 (Student's t-test). (e) qPCR-based changes in the levels of Aldh network genes in 2 h AED (F2) embryos of bacterial-depleted (F1) flies, with and without re-introduction of Actetobacter species in F1. Mean fold-change versus control±s.e., n≥3, *P<0.05, **P<0.01 (Student's t-test). (f) Representative images of DAPI-stained ovaries at day 6 after eclosion of untreated females ('Control') and females developed from dechorionated eggs (Dechor.), Aldh  egg ('Aldh24K ()') and wild type females in which Aldh has been inhibited by exposure to cyanamide throughout the larval and adult stage ('Cynamide'). Note the similar impact of bacterial removal and Aldh loss (or inhibition) on ovary size and the number of mature oocytes. (g) Number of oocytes per ovary and percentages of oocytes in stages 8–10 and 11–14. Data corresponds to the cases in f and to wild-type and Aldh24K  females developed after dechorionation and re-introduction of defined Acetobacter spp. (‘Dechor.+Aceto' and ‘Aldh24K+Aceto', respectively). Mean±s.e. based on three replicated experiments, each with >20 ovaries. **P<0.01 (Student's t-test). (h) Relative egg deposition by 6-day-old Aldh  females, wild type females and females that were developed from Dechorionated eggs. Mean fold-change compared to control±s.e. based on four replicated experiments, each with five vials. **P<0.01 (Student's t-test).
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f3: Lack of Acetobacter appears to suppress oogenesis by repression of Aldh in the ovary.(a) Removal of gut bacteria by dechorionation leads to tissue specific changes of Aldh expression in the larval gut (F1 3rd instar) and in the next generation of embryos (F2, 2 h AED). Mean fold-change (qPCR-based)±s.e. n=3, *** P<0.001 (Student's t-test). (b) RNA-seq measurements of changes in representative genes within the Aldh network (left), compiled using the STRING protein–protein interaction database. Blue labels designate genes that are downregulated in 2 h AED embryos of bacterial-depleted flies versus control. Mean fold-change±s.e. based on duplicates for three lines (six samples per condition). **P<0.01, ***P<0.001 (Wald Statistics, DESeq package). (c) qPCR-based changes in the levels of Aldh network genes in 40 min and 2 h AED embryos of bacterial-depleted flies relative to embryos of untreated flies at the respective time. Mean fold-change±s.e. n=3, *P<0.05, ** P<0.01 (Student's t-test). (d) Enzymatic activity of Aldh in the gut of 3rd instar larvae and ovary of 6-day-old adult females. Shown are data for intact females ('Control') and females that were developed from dechorionated eggs ('Dechor.'), with and without prior re-introduction of Actetobacter or Lactobacillus species. Mean fold-change versus control±s.e., n≥3, *P<0.05, **P<0.01 (Student's t-test). (e) qPCR-based changes in the levels of Aldh network genes in 2 h AED (F2) embryos of bacterial-depleted (F1) flies, with and without re-introduction of Actetobacter species in F1. Mean fold-change versus control±s.e., n≥3, *P<0.05, **P<0.01 (Student's t-test). (f) Representative images of DAPI-stained ovaries at day 6 after eclosion of untreated females ('Control') and females developed from dechorionated eggs (Dechor.), Aldh egg ('Aldh24K ()') and wild type females in which Aldh has been inhibited by exposure to cyanamide throughout the larval and adult stage ('Cynamide'). Note the similar impact of bacterial removal and Aldh loss (or inhibition) on ovary size and the number of mature oocytes. (g) Number of oocytes per ovary and percentages of oocytes in stages 8–10 and 11–14. Data corresponds to the cases in f and to wild-type and Aldh24K females developed after dechorionation and re-introduction of defined Acetobacter spp. (‘Dechor.+Aceto' and ‘Aldh24K+Aceto', respectively). Mean±s.e. based on three replicated experiments, each with >20 ovaries. **P<0.01 (Student's t-test). (h) Relative egg deposition by 6-day-old Aldh females, wild type females and females that were developed from Dechorionated eggs. Mean fold-change compared to control±s.e. based on four replicated experiments, each with five vials. **P<0.01 (Student's t-test).
Mentions: We have previously found that larval exposure to the aminoglycoside antibiotic, G418, leads to selective depletion of gut Acetobacter, which persists in the non-exposed offspring28. In addition to this heritable change in microbiome composition, exposure to G418 led to heritable induction of Drosophila Aldh in the larval foregut43. Since antibiotics also have bacterial-independent effects on the host tissue2728, we tested if the change in Aldh is indeed caused by Acetobacter depletion. Analysis of Aldh expression after removal of gut bacteria by egg dechorionation revealed tissue-specific effects which partly (but not fully) overlap with the effects of G418. Similarly to G418 treatment, dechorionation upregulated Aldh in the gut of 3rd-instar larvae (Fig. 3a, left). However, unlike G418, dechorionation led to downregulation of Aldh in the following generation of embryos (Fig. 3a, right). This reduction of Aldh mRNA in the embryos was accompanied by downregulation of almost all the closely related (‘Aldh network') genes that we compiled using the STRING database44 (Fig. 3b; Supplementary Fig. 4A). A smaller reduction in Aldh mRNA was also observed at 40 min AED (Fig. 3c), suggesting that this reduction is independent of the general decrease of maternal transcripts. This suggestion was further confirmed by analysis of Aldh enzymatic activity which revealed substantial reduction of Aldh activity already in the ovary of bacterial-depleted females (Fig. 3d). The reduction in Aldh activity and the subsequent downregulation of Aldh mRNA in the embryos were both abolished by re-introduction of Acetobacter species (Fig. 3d,e). These findings indicate that depletion of gut Acetobacter affects Aldh expression in a stage- and tissue-specific manner: it upregulates Aldh in the larval gut but represses Aldh in the ovary and in the early embryos of these Acetobacter-free flies.

Bottom Line: Unlike vertically transmitted endosymbionts, which have broad effects on their host's germ line, the extracellular gut microbiota is transmitted horizontally and is not known to influence the germ line.We further show that the main impact on oogenesis is linked to the lack of gut Acetobacter species, and we identify the Drosophila Aldehyde dehydrogenase (Aldh) gene as an apparent mediator of repressed oogenesis in Acetobacter-depleted flies.The finding of interactions between the gut microbiota and the germ line has implications for reproduction, developmental robustness and adaptation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.

ABSTRACT
Unlike vertically transmitted endosymbionts, which have broad effects on their host's germ line, the extracellular gut microbiota is transmitted horizontally and is not known to influence the germ line. Here we provide evidence supporting the influence of these gut bacteria on the germ line of Drosophila melanogaster. Removal of the gut bacteria represses oogenesis, expedites maternal-to-zygotic-transition in the offspring and unmasks hidden phenotypic variation in mutants. We further show that the main impact on oogenesis is linked to the lack of gut Acetobacter species, and we identify the Drosophila Aldehyde dehydrogenase (Aldh) gene as an apparent mediator of repressed oogenesis in Acetobacter-depleted flies. The finding of interactions between the gut microbiota and the germ line has implications for reproduction, developmental robustness and adaptation.

No MeSH data available.


Related in: MedlinePlus