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Metabolomic insights into system-wide coordination of vertebrate metamorphosis.

Ichu TA, Han J, Borchers CH, Lesperance M, Helbing CC - BMC Dev. Biol. (2014)

Bottom Line: The majority of the detected metabolites (74%) showed statistically significant abundance changes (padj < 0.001) between metamorphic stages.We observed extensive remodelling of five core metabolic pathways: arginine and purine/pyrimidine, cysteine/methionine, sphingolipid, and eicosanoid metabolism and the urea cycle, and found evidence for a major role for lipids during this postembryonic process.Metabolites traditionally linked to human disease states were found to have biological linkages to the system-wide changes occuring during the events leading up to overt morphological change.

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Affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada. chelbing@uvic.ca.

ABSTRACT

Background: After completion of embryogenesis, many organisms experience an additional obligatory developmental transition to attain a substantially different juvenile or adult form. During anuran metamorphosis, the aquatic tadpole undergoes drastic morphological changes and remodelling of tissues and organs to become a froglet. Thyroid hormones are required to initiate the process, but the mechanism whereby the many requisite changes are coordinated between organs and tissues is poorly understood. Metabolites are often highly conserved biomolecules between species and are the closest reflection of phenotype. Due to the extensive distribution of blood throughout the organism, examination of the metabolites contained therein provides a system-wide overview of the coordinated changes experienced during metamorphosis. We performed an untargeted metabolomic analysis on serum samples from naturally-metamorphosing Rana catesbeiana from tadpoles to froglets using ultraperformance liquid chromatography coupled to a mass spectrometer. Total and aqueous metabolite extracts were obtained from each serum sample to select for nonpolar and polar metabolites, respectively, and selected metabolites were validated by running authentic compounds.

Results: The majority of the detected metabolites (74%) showed statistically significant abundance changes (padj < 0.001) between metamorphic stages. We observed extensive remodelling of five core metabolic pathways: arginine and purine/pyrimidine, cysteine/methionine, sphingolipid, and eicosanoid metabolism and the urea cycle, and found evidence for a major role for lipids during this postembryonic process. Metabolites traditionally linked to human disease states were found to have biological linkages to the system-wide changes occuring during the events leading up to overt morphological change.

Conclusions: To our knowledge, this is the first wide-scale metabolomic study of vertebrate metamorphosis identifying fundamental pathways involved in the coordination of this important developmental process and paves the way for metabolomic studies on other metamorphic systems including fish and insects.

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Distinct metabolite abundance patterns that were consistently observed in the datasets. After inspecting the abundance patterns of individual metabolites, a total of 13 different expression patterns were observed in the datasets consistently. The frequency of the observed patterns is tabulated in Table 3. (A) Monotonic ↑. (B) Monotonic ↓. (C) ↑ at the froglet stage (TK > XXV). (D) ↓ at the froglet stage (TK > XXV). (E) ↓ after the premetamorphic stage (TK VI–X). (F) ↑after the premetamorphic stage (TK VI–X). (G) ↑ at the metamorphic climax (TK XXI–XXII) then return to a basal level. (H) ↓ at the metamorphic climax (TK XXI–XXII) then return to a basal level. (I) ↑ at the metamorphic climax (TK XXI–XXII) followed by ↓ at the froglet stage (TK > XXV). (J) ↓ at the metamorphic climax (TK XXI–XXII) followed by ↑ at the froglet stage (TK > XXV). (K) Significant abundance change at the metamorphic climax, and the abundance remains constant at the froglet stage. (L) Step-wise ↑ or ↓. (M) Significant variation (significant unequal variance determined by the Levene’s test, padj < 0.01).
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Figure 2: Distinct metabolite abundance patterns that were consistently observed in the datasets. After inspecting the abundance patterns of individual metabolites, a total of 13 different expression patterns were observed in the datasets consistently. The frequency of the observed patterns is tabulated in Table 3. (A) Monotonic ↑. (B) Monotonic ↓. (C) ↑ at the froglet stage (TK > XXV). (D) ↓ at the froglet stage (TK > XXV). (E) ↓ after the premetamorphic stage (TK VI–X). (F) ↑after the premetamorphic stage (TK VI–X). (G) ↑ at the metamorphic climax (TK XXI–XXII) then return to a basal level. (H) ↓ at the metamorphic climax (TK XXI–XXII) then return to a basal level. (I) ↑ at the metamorphic climax (TK XXI–XXII) followed by ↓ at the froglet stage (TK > XXV). (J) ↓ at the metamorphic climax (TK XXI–XXII) followed by ↑ at the froglet stage (TK > XXV). (K) Significant abundance change at the metamorphic climax, and the abundance remains constant at the froglet stage. (L) Step-wise ↑ or ↓. (M) Significant variation (significant unequal variance determined by the Levene’s test, padj < 0.01).

Mentions: A box plot of log2 transformed peak areas versus TK stage ranges was created for each metabolite, and the abundance pattern produced was inspected. In total, 13 different metabolite abundance patterns were consistently observed in the datasets (Figure 2). These patterns show how tightly metabolites are regulated during metamorphosis. The frequency of these patterns was counted and tabulated (Table 3), and the top three most common classifiable patterns were: a significant decrease at the froglet stage (pattern = Figure 2D), a significant increase around the metamorphic climax and a return to basal level (pattern = Figure 2G), and a significant increase at metamorphic climax followed by a significant decrease at the froglet stage (pattern = Figure 2I). A significant decrease in the abundance of metabolites at the froglet stage accentuates how metabolically different the frog is compared to larvae upon completion of metamorphosis. A significant increase at the metamorphic climax correlates with the circulating level of THs [14]. These abundance patterns imply that the metamorphic climax is where a large fraction of metabolites exhibit an abundance change in anticipation of drastic morphological changes.


Metabolomic insights into system-wide coordination of vertebrate metamorphosis.

Ichu TA, Han J, Borchers CH, Lesperance M, Helbing CC - BMC Dev. Biol. (2014)

Distinct metabolite abundance patterns that were consistently observed in the datasets. After inspecting the abundance patterns of individual metabolites, a total of 13 different expression patterns were observed in the datasets consistently. The frequency of the observed patterns is tabulated in Table 3. (A) Monotonic ↑. (B) Monotonic ↓. (C) ↑ at the froglet stage (TK > XXV). (D) ↓ at the froglet stage (TK > XXV). (E) ↓ after the premetamorphic stage (TK VI–X). (F) ↑after the premetamorphic stage (TK VI–X). (G) ↑ at the metamorphic climax (TK XXI–XXII) then return to a basal level. (H) ↓ at the metamorphic climax (TK XXI–XXII) then return to a basal level. (I) ↑ at the metamorphic climax (TK XXI–XXII) followed by ↓ at the froglet stage (TK > XXV). (J) ↓ at the metamorphic climax (TK XXI–XXII) followed by ↑ at the froglet stage (TK > XXV). (K) Significant abundance change at the metamorphic climax, and the abundance remains constant at the froglet stage. (L) Step-wise ↑ or ↓. (M) Significant variation (significant unequal variance determined by the Levene’s test, padj < 0.01).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3928663&req=5

Figure 2: Distinct metabolite abundance patterns that were consistently observed in the datasets. After inspecting the abundance patterns of individual metabolites, a total of 13 different expression patterns were observed in the datasets consistently. The frequency of the observed patterns is tabulated in Table 3. (A) Monotonic ↑. (B) Monotonic ↓. (C) ↑ at the froglet stage (TK > XXV). (D) ↓ at the froglet stage (TK > XXV). (E) ↓ after the premetamorphic stage (TK VI–X). (F) ↑after the premetamorphic stage (TK VI–X). (G) ↑ at the metamorphic climax (TK XXI–XXII) then return to a basal level. (H) ↓ at the metamorphic climax (TK XXI–XXII) then return to a basal level. (I) ↑ at the metamorphic climax (TK XXI–XXII) followed by ↓ at the froglet stage (TK > XXV). (J) ↓ at the metamorphic climax (TK XXI–XXII) followed by ↑ at the froglet stage (TK > XXV). (K) Significant abundance change at the metamorphic climax, and the abundance remains constant at the froglet stage. (L) Step-wise ↑ or ↓. (M) Significant variation (significant unequal variance determined by the Levene’s test, padj < 0.01).
Mentions: A box plot of log2 transformed peak areas versus TK stage ranges was created for each metabolite, and the abundance pattern produced was inspected. In total, 13 different metabolite abundance patterns were consistently observed in the datasets (Figure 2). These patterns show how tightly metabolites are regulated during metamorphosis. The frequency of these patterns was counted and tabulated (Table 3), and the top three most common classifiable patterns were: a significant decrease at the froglet stage (pattern = Figure 2D), a significant increase around the metamorphic climax and a return to basal level (pattern = Figure 2G), and a significant increase at metamorphic climax followed by a significant decrease at the froglet stage (pattern = Figure 2I). A significant decrease in the abundance of metabolites at the froglet stage accentuates how metabolically different the frog is compared to larvae upon completion of metamorphosis. A significant increase at the metamorphic climax correlates with the circulating level of THs [14]. These abundance patterns imply that the metamorphic climax is where a large fraction of metabolites exhibit an abundance change in anticipation of drastic morphological changes.

Bottom Line: The majority of the detected metabolites (74%) showed statistically significant abundance changes (padj < 0.001) between metamorphic stages.We observed extensive remodelling of five core metabolic pathways: arginine and purine/pyrimidine, cysteine/methionine, sphingolipid, and eicosanoid metabolism and the urea cycle, and found evidence for a major role for lipids during this postembryonic process.Metabolites traditionally linked to human disease states were found to have biological linkages to the system-wide changes occuring during the events leading up to overt morphological change.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada. chelbing@uvic.ca.

ABSTRACT

Background: After completion of embryogenesis, many organisms experience an additional obligatory developmental transition to attain a substantially different juvenile or adult form. During anuran metamorphosis, the aquatic tadpole undergoes drastic morphological changes and remodelling of tissues and organs to become a froglet. Thyroid hormones are required to initiate the process, but the mechanism whereby the many requisite changes are coordinated between organs and tissues is poorly understood. Metabolites are often highly conserved biomolecules between species and are the closest reflection of phenotype. Due to the extensive distribution of blood throughout the organism, examination of the metabolites contained therein provides a system-wide overview of the coordinated changes experienced during metamorphosis. We performed an untargeted metabolomic analysis on serum samples from naturally-metamorphosing Rana catesbeiana from tadpoles to froglets using ultraperformance liquid chromatography coupled to a mass spectrometer. Total and aqueous metabolite extracts were obtained from each serum sample to select for nonpolar and polar metabolites, respectively, and selected metabolites were validated by running authentic compounds.

Results: The majority of the detected metabolites (74%) showed statistically significant abundance changes (padj < 0.001) between metamorphic stages. We observed extensive remodelling of five core metabolic pathways: arginine and purine/pyrimidine, cysteine/methionine, sphingolipid, and eicosanoid metabolism and the urea cycle, and found evidence for a major role for lipids during this postembryonic process. Metabolites traditionally linked to human disease states were found to have biological linkages to the system-wide changes occuring during the events leading up to overt morphological change.

Conclusions: To our knowledge, this is the first wide-scale metabolomic study of vertebrate metamorphosis identifying fundamental pathways involved in the coordination of this important developmental process and paves the way for metabolomic studies on other metamorphic systems including fish and insects.

Show MeSH
Related in: MedlinePlus