J Exp Biol Advance Online Articles. First posted online on 27 February 2014 as doi:10.1242/jeb.101725 Access the most recent version at http://jeb.biologists.org/lookup/doi/10.1242/jeb.101725
1 2 3
Gut microbiota dictates the metabolic response of Drosophila to diet
The Journal of Experimental Biology – ACCEPTED AUTHOR MANUSCRIPT
4 5
Adam C-N. Wong1,3*#, Adam J. Dobson1,4* and Angela E. Douglas1,2
6
1
7
University, Ithaca, NY14853, USA
Department of Entomology, 2Department of Molecular Biology and Genetics, Cornell
8 9 10 11 12 13 14
Present addresses: 3
Present address of A.C-N.W: School of Biological Sciences, University of Sydney, Australia
NSW 2006. 4
Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University
College London, Darwin Building, Gower Street, London WC1E 6BT, UK.
15 16 17 18
* co-first authors
19
#Author for correspondence: School of Biological Sciences, University of Sydney, Australia
20
NSW 2006. email [email protected]
21 22 23
Short title: Drosophila-microbiota interactions
24 25 26
Key words: Bvitamins; Drosophila; gut microbiota; hyperlipidemia; protein nutrition; symbiosis
27
1
© 2013. Published by The Company of Biologists Ltd
The Journal of Experimental Biology – ACCEPTED AUTHOR MANUSCRIPT
28
SUMMARY
29
Animal nutrition is profoundly influenced by the gut microbiota, but knowledge of the scope
30
and underlying mechanisms of the underlying animal-microbial interactions is fragmentary.
31
To investigate the nutritional traits shaped by the gut microbiota of Drosophila, we
32
determined the microbiota-dependent response of multiple metabolic and performance
33
indices to systematically-varied diet composition. Diet-dependent differences between
34
Drosophila bearing its unmanipulated microbiota (conventional flies) and experimentally
35
deprived of its microbiota (axenic flies) revealed evidence for: microbial sparing of dietary B
36
vitamins, especially riboflavin, on low-yeast diets; microbial promotion of protein nutrition,
37
particularly in females; and microbiota-mediated suppression of lipid/carbohydrate storage,
38
especially on high sugar diets. The microbiota also set the relationship between energy
39
storage and body weight, indicative of microbial modulation of the host signaling networks
40
that coordinate metabolism with body size. This analysis identifies the multiple impacts of
41
the microbiota on the metabolism of Drosophila, and demonstrates that the significance of
42
these different interactions varies with diet composition and host sex.
43
2
The Journal of Experimental Biology – ACCEPTED AUTHOR MANUSCRIPT
44
INTRODUCTION
45
The resident gut microbiota plays a pivotal role in animal nutrition (Flint et al., 2012; Karasov
46
and Douglas, 2013). These microorganisms engage with animal acquisition and allocation of
47
nutrients, the two key processes that shape the nutrition of an animal, in multiple ways. They
48
can consume ingested nutrients or provide supplementary nutrients to the host; they can alter
49
the feeding and nutrient assimilation rates; and they can modify nutrient allocation patterns of the
50
host by modulating the nutrient sensing and signaling pathways of the animal host (Backhed et
51
al., 2004; Caricilli and Saad, 2013; Goodman et al., 2009; Vijay-Kumar et al., 2010). Multiple
52
studies indicate that the resident microorganisms generally promote animal nutrition, although
53
the nutritional benefit can vary with diet, composition of the microbiota and animal genotype
54
(Benson et al., 2010; Kau et al., 2011; Parks et al., 2013; Smith et al., 2013). Mismatch between
55
the microbiota and animal results in poor host health, a condition known as dysbiosis (Nicholson
56
et al., 2012; Stecher et al., 2013).
57
Much of current understanding of the nutritional significance of the microbiota in animals
58
comes from comparisons between untreated animals bearing the microbiota (conventional
59
animals) and animals deprived of their microbiota (germ-free/axenic animals) (Gordon and Pesti,
60
1971; Smith et al., 2007; Yi and Li, 2012). Most of these studies are conducted on a single diet,
61
or a few diets in which either a single nutritional component or total nutrient concentration is
62
altered. However, inclusive information on the nutritional significance of microorganisms to
63
their animal host can only be obtained from comparative analyses using diets of systematically
64
varied composition. For example, disproportionately low performance of axenic animals,
65
relative to conventional animals, on certain diets can be attributed to microbial production of
66
nutrients that are deficient in the diet and/or microbial consumption of dietary nutrients in
67
excess; and the performance of axenic animals can be superior to conventional animals where the
68
microbiota depresses host access to nutrients in short dietary supply. Parallel analysis of the host
69
metabolic composition, especially major classes of macronutrients (protein, lipid etc.), provides
70
additional insight into the impact of the microbiota on the nutrient allocation patterns of the host.
71
This study on the microbiota-dependent response of animals to diet was conducted on
72
Drosophila melanogaster, which is well-suited to large experimental designs involving extensive
73
dietary manipulations. The gut microbiota which is dominated by members of the
74
Acetobacteraceae and Lactobacillales (Chandler et al., 2011; Wong et al., 2011 & 2013) has 3
The Journal of Experimental Biology – ACCEPTED AUTHOR MANUSCRIPT
75
substantive effects on Drosophila (Broderick and Lemaitre, 2012; Erkosar et al., 2013). Axenic
76
Drosophila display extended larval development time and, in some studies, depressed adult
77
weight and total lifespan (Bakula, 1969; Brummel et al., 2004; Ren et al., 2007; Ridley et al.,
78
2012; Shin et al., 2011; Storelli et al., 2011). Elimination or perturbation of the microbiota can
79
also result in altered metabolic indices, including elevated lipid and carbohydrate levels, together
80
with reduced basal metabolic rates (Ridley et al., 2012; Shin et al., 2011). Furthermore, there is
81
evidence that the Drosophila nutrient signaling pathways, especially insulin/TOR signaling, are
82
sensitive to the microbiota, but the mechanistic detail is uncertain (Shin et al., 2011; Storelli et
83
al., 2011).
84
The specific aim of this study was to determine the complement of nutritional interactions
85
between Drosophila melanogaster and its microbiota by comparing the performance and
86
metabolic indices of conventional and axenic flies on diets of systematically varied composition.
87
Our analysis reveals that the microbiota enables Drosophila to utilize low-nutrient/unbalanced
88
diets by sparing the requirement for dietary B vitamins, promotes protein nutrition, and
89
suppresses energy (lipid/carbohydrate) storage, especially on high sugar diets.
90 91 92
RESULTS
93
Drosophila performance
94
The first experiments quantified the survival and development time to adulthood of axenic and
95
conventional Drosophila on 16 diets containing glucose and yeast, both at concentrations
96
systematically varied over an eight-fold range (25-200 g l-1). Pre-adult mortality of conventional
97
Drosophila was p>0.01,
532
**0.01>p>0.001, ****p
1 2 3
Gut microbiota dictates the metabolic response of Drosophila to diet
The Journal of Experimental Biology – ACCEPTED AUTHOR MANUSCRIPT
4 5
Adam C-N. Wong1,3*#, Adam J. Dobson1,4* and Angela E. Douglas1,2
6
1
7
University, Ithaca, NY14853, USA
Department of Entomology, 2Department of Molecular Biology and Genetics, Cornell
8 9 10 11 12 13 14
Present addresses: 3
Present address of A.C-N.W: School of Biological Sciences, University of Sydney, Australia
NSW 2006. 4
Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University
College London, Darwin Building, Gower Street, London WC1E 6BT, UK.
15 16 17 18
* co-first authors
19
#Author for correspondence: School of Biological Sciences, University of Sydney, Australia
20
NSW 2006. email [email protected]
21 22 23
Short title: Drosophila-microbiota interactions
24 25 26
Key words: Bvitamins; Drosophila; gut microbiota; hyperlipidemia; protein nutrition; symbiosis
27
1
© 2013. Published by The Company of Biologists Ltd
The Journal of Experimental Biology – ACCEPTED AUTHOR MANUSCRIPT
28
SUMMARY
29
Animal nutrition is profoundly influenced by the gut microbiota, but knowledge of the scope
30
and underlying mechanisms of the underlying animal-microbial interactions is fragmentary.
31
To investigate the nutritional traits shaped by the gut microbiota of Drosophila, we
32
determined the microbiota-dependent response of multiple metabolic and performance
33
indices to systematically-varied diet composition. Diet-dependent differences between
34
Drosophila bearing its unmanipulated microbiota (conventional flies) and experimentally
35
deprived of its microbiota (axenic flies) revealed evidence for: microbial sparing of dietary B
36
vitamins, especially riboflavin, on low-yeast diets; microbial promotion of protein nutrition,
37
particularly in females; and microbiota-mediated suppression of lipid/carbohydrate storage,
38
especially on high sugar diets. The microbiota also set the relationship between energy
39
storage and body weight, indicative of microbial modulation of the host signaling networks
40
that coordinate metabolism with body size. This analysis identifies the multiple impacts of
41
the microbiota on the metabolism of Drosophila, and demonstrates that the significance of
42
these different interactions varies with diet composition and host sex.
43
2
The Journal of Experimental Biology – ACCEPTED AUTHOR MANUSCRIPT
44
INTRODUCTION
45
The resident gut microbiota plays a pivotal role in animal nutrition (Flint et al., 2012; Karasov
46
and Douglas, 2013). These microorganisms engage with animal acquisition and allocation of
47
nutrients, the two key processes that shape the nutrition of an animal, in multiple ways. They
48
can consume ingested nutrients or provide supplementary nutrients to the host; they can alter
49
the feeding and nutrient assimilation rates; and they can modify nutrient allocation patterns of the
50
host by modulating the nutrient sensing and signaling pathways of the animal host (Backhed et
51
al., 2004; Caricilli and Saad, 2013; Goodman et al., 2009; Vijay-Kumar et al., 2010). Multiple
52
studies indicate that the resident microorganisms generally promote animal nutrition, although
53
the nutritional benefit can vary with diet, composition of the microbiota and animal genotype
54
(Benson et al., 2010; Kau et al., 2011; Parks et al., 2013; Smith et al., 2013). Mismatch between
55
the microbiota and animal results in poor host health, a condition known as dysbiosis (Nicholson
56
et al., 2012; Stecher et al., 2013).
57
Much of current understanding of the nutritional significance of the microbiota in animals
58
comes from comparisons between untreated animals bearing the microbiota (conventional
59
animals) and animals deprived of their microbiota (germ-free/axenic animals) (Gordon and Pesti,
60
1971; Smith et al., 2007; Yi and Li, 2012). Most of these studies are conducted on a single diet,
61
or a few diets in which either a single nutritional component or total nutrient concentration is
62
altered. However, inclusive information on the nutritional significance of microorganisms to
63
their animal host can only be obtained from comparative analyses using diets of systematically
64
varied composition. For example, disproportionately low performance of axenic animals,
65
relative to conventional animals, on certain diets can be attributed to microbial production of
66
nutrients that are deficient in the diet and/or microbial consumption of dietary nutrients in
67
excess; and the performance of axenic animals can be superior to conventional animals where the
68
microbiota depresses host access to nutrients in short dietary supply. Parallel analysis of the host
69
metabolic composition, especially major classes of macronutrients (protein, lipid etc.), provides
70
additional insight into the impact of the microbiota on the nutrient allocation patterns of the host.
71
This study on the microbiota-dependent response of animals to diet was conducted on
72
Drosophila melanogaster, which is well-suited to large experimental designs involving extensive
73
dietary manipulations. The gut microbiota which is dominated by members of the
74
Acetobacteraceae and Lactobacillales (Chandler et al., 2011; Wong et al., 2011 & 2013) has 3
The Journal of Experimental Biology – ACCEPTED AUTHOR MANUSCRIPT
75
substantive effects on Drosophila (Broderick and Lemaitre, 2012; Erkosar et al., 2013). Axenic
76
Drosophila display extended larval development time and, in some studies, depressed adult
77
weight and total lifespan (Bakula, 1969; Brummel et al., 2004; Ren et al., 2007; Ridley et al.,
78
2012; Shin et al., 2011; Storelli et al., 2011). Elimination or perturbation of the microbiota can
79
also result in altered metabolic indices, including elevated lipid and carbohydrate levels, together
80
with reduced basal metabolic rates (Ridley et al., 2012; Shin et al., 2011). Furthermore, there is
81
evidence that the Drosophila nutrient signaling pathways, especially insulin/TOR signaling, are
82
sensitive to the microbiota, but the mechanistic detail is uncertain (Shin et al., 2011; Storelli et
83
al., 2011).
84
The specific aim of this study was to determine the complement of nutritional interactions
85
between Drosophila melanogaster and its microbiota by comparing the performance and
86
metabolic indices of conventional and axenic flies on diets of systematically varied composition.
87
Our analysis reveals that the microbiota enables Drosophila to utilize low-nutrient/unbalanced
88
diets by sparing the requirement for dietary B vitamins, promotes protein nutrition, and
89
suppresses energy (lipid/carbohydrate) storage, especially on high sugar diets.
90 91 92
RESULTS
93
Drosophila performance
94
The first experiments quantified the survival and development time to adulthood of axenic and
95
conventional Drosophila on 16 diets containing glucose and yeast, both at concentrations
96
systematically varied over an eight-fold range (25-200 g l-1). Pre-adult mortality of conventional
97
Drosophila was p>0.01,
532
**0.01>p>0.001, ****p
