Cloning of FITM2 gene and investigating its expression levels in Banna miniature inbred pig (Sus scrofa) tissues.

Fat storage-inducing transmembrane protein 2 (FITM2) plays an important role in regulating lipid storage and could be regarded as a candidate gene for intramuscular fat deposition in pigs. The aim of this study was to clone the coding domain sequence (CDS) of FITM2 gene, to compare the nucleotide acid and deduced amino acid sequences between breeds and species, to analyze the structure and characteristics of protein and to detect the expression profile of gene. The results exhibited that the CDS of FITM2 gene was 789 bp in length. The mutation of nucleotide acids led to the mutation of deduced amino acids between Banna miniature inbred pigs and other two breeds (Yorkshire × Landrace pigs and Duroc × (Landrace × Yorkshire) pigs). It was indicated that high identities of nucleotide acid and deduced amino acid sequences between Banna miniature inbred pigs and other species. The deduced amino acids were composed of loops and alpha helices in the structure. FITM2 protein may be a 30 kDa hydrophobic protein with 26 phosphorylation sites and one potential N-glycosylated site. FITM2 gene was widely expressed in various tissues, and the highest expression level was in adipose tissue.

Application of Caenorhabditis elegans in Lipid Metabolism Research.

Over the last decade, the development and prevalence of obesity have posed a serious public health risk, which has prompted studies on the regulation of adiposity. With the ease of genetic manipulation, the diversity of the methods for characterizing body fat levels, and the observability of feeding behavior, Caenorhabditis elegans (C. elegans) is considered an excellent model for exploring energy homeostasis and the regulation of the cellular fat storage. In addition, the homology with mammals in the genes related to the lipid metabolism allows many aspects of lipid modulation by the regulators of the central nervous system to be conserved in this ideal model organism. In recent years, as the complex network of genes that maintain an energy balance has been gradually expanded and refined, the regulatory mechanisms of lipid storage have become clearer. Furthermore, the development of methods and devices to assess the lipid levels has become a powerful tool for studies in lipid droplet biology and the regulation of the nematode lipid metabolism. Herein, based on the rapid progress of C. elegans lipid metabolism-related studies, this review outlined the lipid metabolic processes, the major signaling pathways of fat storage regulation, and the primary experimental methods to assess the lipid content in nematodes. Therefore, this model system holds great promise for facilitating the understanding, management, and therapies of human obesity and other metabolism-related diseases.

Fat storage-inducing transmembrane proteins: beyond mediating lipid droplet formation.

Fat storage-inducing transmembrane proteins (FITMs) were initially identified in 2007 as members of a conserved endoplasmic reticulum (ER) resident transmembrane protein gene family, and were found to be involved in lipid droplet (LD) formation. Recently, several studies have further demonstrated that the ability of FITMs to directly bind to triglyceride and diacylglycerol, and the diphosphatase activity of hydrolyzing fatty acyl-CoA, might enable FITMs to maintain the formation of lipid droplets, engage in lipid metabolism, and protect against cellular stress. Based on the distribution of FITMs in tissues and their important roles in lipid droplet biology and lipid metabolism, it was discovered that FITMs were closely related to muscle development, adipocyte differentiation, and energy metabolism. Accordingly, the abnormal expression of FITMs was not only associated with type 2 diabetes and lipodystrophy, but also with cardiac disease and several types of cancer. This study reviews the structure, distribution, expression regulation, and functionality of FITMs and their potential relationships with various metabolic diseases, hoping to provide inspiration for fruitful research directions and applications of FITM proteins. Moreover, this review will provide an important theoretical basis for the application of FITMs in the diagnosis and treatment of related diseases.

Spatiotemporal variation in the fecal microbiota of mule deer is associated with proximate and future measures of host health.

BACKGROUND: Mule deer rely on fat and protein stored prior to the winter season as an energy source during the winter months when other food sources are sparse. Since associated microorganisms ('microbiota') play a significant role in nutrient metabolism of their hosts, we predicted that variation in the microbiota might be associated with nutrient storage and overwintering in mule deer populations. To test this hypothesis we performed a 16S rRNA marker gene survey of fecal samples from two deer populations in the western United States before and after onset of winter. RESULTS: PERMANOVA analysis revealed the deer microbiota varied interactively with geography and season. Further, using metadata collected at the time of sampling, we were able to identify different fecal bacterial taxa that could potentially act as bioindicators of mule deer health outcomes. First, we identified the abundance of Collinsella (family: Coriobacteriaceae) reads as a possible predictor of poor overwintering outcomes for deer herds in multiple locations. Second, we showed that reads assigned to the Bacteroides and Mollicutes Order RF39 were both positively correlated with deer protein levels, leading to the idea that these sequences might be useful in predicting mule deer protein storage. CONCLUSIONS: These analyses confirm that variation in the microbiota is associated with season-dependent health outcomes in mule deer, which may have useful implications for herd management strategies.

Negative hepatic computed tomographic attenuation pattern in a dog with vacuolar hepatopathy and hepatic fat accumulation secondary to cushing's syndrome.

This report describes an unusual computed tomographic (CT) hepatic pattern, characterized by negative attenuation values (from -19.59 to -28.85 Hounsfield Units, HU) in a canine patient with severe Cushing's syndrome. Attenuation values of the splenic parenchyma (63.26 HU) and abdominal fat (-118.34 HU) were within normal limits. The negative hepatic attenuation values allowed a CT diagnosis of severe hepatic fatty infiltration that was subsequently confirmed by tissue-core biopsy and histopathological examination.

Fructose-containing caloric sweeteners as a cause of obesity and metabolic disorders.

Compared with other carbohydrates, fructose-containing caloric sweeteners (sucrose, high-fructose corn syrup, pure fructose and fructose-glucose mixtures) are characterized by: a sweet taste generally associated with a positive hedonic tone; specific intestinal fructose transporters, i.e. GLUT5; a two-step fructose metabolism, consisting of the conversion of fructose carbones into ubiquitous energy substrates in splanchnic organs where fructolytic enzymes are expressed, and secondary delivery of these substrates to extrasplanchnic tissues. Fructose is a dispensable nutrient, yet its energy can be stored very efficiently owing to a rapid induction of intestinal fructose transporters and of splanchnic fructolytic and lipogenic enzymes by dietary fructose-containing caloric sweeteners. In addition, compared with fat or other dietary carbohydrates, fructose may be favored as an energy store because it uses different intestinal absorption mechanisms and different inter-organ trafficking pathways. These specific features make fructose an advantageous energy substrate in wild animals, mainly when consumed before periods of scarcity or high energy turnover such as migrations. These properties of fructose storage are also advantageous to humans who are involved in strenuous sport activities. In subjects with low physical activity, however, these same features of fructose metabolism may have the harmful effect of favoring energy overconsumption. Furthermore, a continuous exposure to high fructose intake associated with a low energy turnover leads to a chronic overproduction of intrahepatic trioses-phosphate production, which is secondarily responsible for the development of hepatic insulin resistance, intrahepatic fat accumulation, and increased blood triglyceride concentrations. In the long term, these effects may contribute to the development of metabolic and cardiovascular diseases.

Mouse fat storage-inducing transmembrane protein 2 (FIT2) promotes lipid droplet accumulation in plants.

Fat storage-inducing transmembrane protein 2 (FIT2) is an endoplasmic reticulum (ER)-localized protein that plays an important role in lipid droplet (LD) formation in animal cells. However, no obvious homologue of FIT2 is found in plants. Here, we tested the function of FIT2 in plant cells by ectopically expressing mouse (Mus musculus) FIT2 in Nicotiana tabacum suspension-cultured cells, Nicotiana benthamiana leaves and Arabidopsis thaliana plants. Confocal microscopy indicated that the expression of FIT2 dramatically increased the number and size of LDs in leaves of N. benthamiana and Arabidopsis, and lipidomics analysis and mass spectrometry imaging confirmed the accumulation of neutral lipids in leaves. FIT2 also increased seed oil content by ~13% in some stable, overexpressing lines of Arabidopsis. When expressed transiently in leaves of N. benthamiana or suspension cells of N. tabacum, FIT2 localized specifically to the ER and was often concentrated at certain regions of the ER that resembled ER-LD junction sites. FIT2 also colocalized at the ER with other proteins known to be involved in triacylglycerol biosynthesis or LD formation in plants, but not with ER resident proteins involved in electron transfer or ER-vesicle exit sites. Collectively, these results demonstrate that mouse FIT2 promotes LD accumulation in plants, a surprising functional conservation in the context of a plant cell given the apparent lack of FIT2 homologues in higher plants. These results suggest also that FIT2 expression represents an effective synthetic biology strategy for elaborating neutral lipid compartments in plant tissues for potential biofuel or bioproduct purposes.

High peripheral temperatures in king penguins while resting at sea: thermoregulation versus fat deposition.

Marine endotherms living in cold water face an energetically challenging situation. Unless properly insulated, these animals will lose heat rapidly. The field metabolic rate of king penguins at sea is about twice that on land. However, when at sea, their metabolic rate is higher during extended resting periods at the surface than during foraging, when birds descend to great depth in pursuit of their prey. This is most likely explained by differences in thermal status. During foraging, peripheral vasoconstriction leads to a hypothermic shell, which is rewarmed during extended resting bouts at the surface. Maintaining peripheral perfusion during rest in cold water, however, will greatly increase heat loss and, therefore, thermoregulatory costs. Two hypotheses have been proposed to explain the maintenance of a normothermic shell during surface rest: (1) to help the unloading of N2 accumulated during diving; and (2) to allow the storage of fat in subcutaneous tissue, following the digestion of food. We tested the latter hypothesis by maintaining king penguins within a shallow seawater tank, while we recorded tissue temperature at four distinct sites. When king penguins were released into the tank during the day, their body temperature immediately declined. However, during the night, periodic rewarming of abdominal and peripheral tissues occurred, mimicking temperature patterns observed in the wild. Body temperatures, particularly in the flank, also depended on body condition and were higher in 'lean' birds (after 10 days of fasting) than in 'fat' birds. While not explicitly tested, our observation that nocturnal rewarming persists in the absence of diving activity during the day does not support the N2 unloading hypothesis. Rather, differences in temperature changes throughout the day and night, and the effect of body condition/mass supports the hypothesis that tissue perfusion during rest is required for nutritional needs.

WAT apoC-I secretion: role in delayed chylomicron clearance in vivo and ex vivo in WAT in obese subjects.

Reduced white adipose tissue (WAT) LPL activity delays plasma clearance of TG-rich lipoproteins (TRLs). We reported the secretion of apoC-I, an LPL inhibitor, from WAT ex vivo in women. Therefore we hypothesized that WAT-secreted apoC-I associates with reduced WAT LPL activity and TRL clearance. WAT apoC-I secretion averaged 86.9 ± 31.4 pmol/g/4 h and 74.1 ± 36.6 pmol/g/4 h in 28 women and 11 men with BMI ≥27 kg/m(2), respectively, with no sex differences. Following the ingestion of a (13)C-triolein-labeled high-fat meal, subjects with high WAT apoC-I secretion (above median) had delayed postprandial plasma clearance of dietary TRLs, assessed from plasma (13)C-triolein-labeled TGs and apoB48. They also had reduced hydrolysis and storage of synthetic (3)H-triolein-labeled ((3)H)-TRLs in WAT ex vivo (i.e., in situ LPL activity). Adjusting for WAT in situ LPL activity eliminated group differences in chylomicron clearance; while adjusting for plasma apoC-I, (3)H-NEFA uptake by WAT, or body composition did not. apoC-I inhibited in situ LPL activity in adipocytes in both a concentration- and time-dependent manner. There was no change in postprandial WAT apoC-I secretion. WAT apoC-I secretion may inhibit WAT LPL activity and promote delayed chylomicron clearance in overweight and obese subjects. We propose that reducing WAT apoC-I secretion ameliorates postprandial TRL clearance in humans.

Quantum dots increased fat storage in intestine of Caenorhabditis elegans by influencing molecular basis for fatty acid metabolism.

Caenorhabditis elegans is a useful model animal for fat storage study. In nematodes, CdTe quantum dots (QDs) induced an increase in fat storage in intestine that is partially due to prolonged defecation cycle length, and not attributed to altered feeding or cadmium ion released from CdTe QDs. Moreover, CdTe QDs altered the molecular basis of both synthesis and degradation of fatty acid; however, CdTe QDs did not influence that of degradation of phospholipids. CdTe QDs increased expression of fasn-1 and pod-2 genes encoding enzymes required for fatty acid synthesis, and decreased expression of acs-2 and ech-1 genes encoding enzymes required for fatty acid ß-oxidation. The altered molecular basis of fatty acid synthesis or degradation by CdTe QDs acted in intestine to regulate fat storage. Our study highlights the potential of CdTe QDs in influencing lipid metabolism in certain organs or tissues in animals.

The control of lipid metabolism by mRNA splicing in Drosophila.

The storage of lipids is an evolutionarily conserved process that is important for the survival of organisms during shifts in nutrient availability. Triglycerides are stored in lipid droplets, but the mechanisms of how lipids are stored in these structures are poorly understood. Previous in vitro RNAi screens have implicated several components of the spliceosome in controlling lipid droplet formation and storage, but the in vivo relevance of these phenotypes is unclear. In this study, we identify specific members of the splicing machinery that are necessary for normal triglyceride storage in the Drosophila fat body. Decreasing the expression of the splicing factors U1-70K, U2AF38, U2AF50 in the fat body resulted in decreased triglyceride levels. Interestingly, while decreasing the SR protein 9G8 in the larval fat body yielded a similar triglyceride phenotype, its knockdown in the adult fat body resulted in a substantial increase in lipid stores. This increase in fat storage is due in part to altered splicing of the gene for the ß-oxidation enzyme CPT1, producing an isoform with less enzymatic activity. Together, these data indicate a role for mRNA splicing in regulating lipid storage in Drosophila and provide a link between the regulation of gene expression and lipid homeostasis.

Effect of repeatedly applied cold water immersion on subclinical atherosclerosis, inflammation, fat accumulation and lipid profile parameters of volunteers.

Significant acute cardiovascular, metabolic, and endocrine changes have been traced to short-lasting cold water immersion (CWI); however, the long-term impact of recurrent CWI on atherogenesis, lipid parameters, and fat distribution has not yet been studied. The goal of this study was to investigate the alleged protective effect. A total of 35 healthy volunteers were monitored for a period of 5 months during which the CWI was performed under standardized conditions (three times per week for 7-10 min, without neoprene equipment). Volunteers with measured weight or muscle mass increases of more than 5% were ineligible. An analogous control group (N = 30) was included. At the onset and completion of the study, blood samples were obtained, and clinical assessments took place. PCSK9 and hsCRP levels were measured together with other lipid-related and non-lipid-related indicators. Carotid intima-media thickness test (cIMT) and echo-tracking for the identification of arterial stiffness (PWV, AI, and ß) were used to identify early vascular alterations. Hepatorenal index (HRI) calculations served to quantify liver steatosis, while changes in subcutaneous and visceral fat thickness were used to quantify fat distribution. The given protocol was successfully completed by 28 volunteers. Long-term repeated CWI resulted in a significant decline in cIMT (p = 0.0001), AI (p = 0.0002), Beta (p = 0.0001), and PWV (p = 0.0001). PCSK9 (p = 0.01) and hsCRP (p = 0.01) showed a significant decrease when compared to initial values. In comparison to the starting values, liver fat accumulation decreased by 11% on average (HRI p = 0.001). LDL, TC, TG, and VLDL levels all significantly decreased as well. We suggest that repeated CWI may have beneficial impact on lipid, non-lipid, and lipid-related indices, as well as atherogenesis and liver fat storage.

Molecular dynamics simulations of intracellular lipid droplets: a new tool in the toolbox.

Lipid droplets (LDs) are ubiquitous intracellular organelles with a central role in multiple lipid metabolic pathways. However, identifying correlations between their structural properties and their biological activity has proved challenging, owing to their unique physicochemical properties as compared with other cellular membranes. In recent years, molecular dynamics (MD) simulations, a computational methodology allowing the accurate description of molecular assemblies down to their individual components, have been demonstrated to be a useful and powerful approach for studying LD structural and dynamical properties. In this short review, we attempt to highlight, as comprehensively as possible, how MD simulations have contributed to our current understanding of multiple molecular mechanisms involved in LD biology.

Shifts in energy allocation and reproduction in response to temperature in a small precocial mammal.

BACKGROUND: Species adjust to changes in temperature and the accompanying reduction in resource availability during the annual cycle by shifts in energy allocation. As it gets colder, the priority of energy allocation to maintenance increases and reproduction is reduced or abandoned. RESULTS: We studied whether and how young female guinea pigs (Cavia porcellus) adjust even under ad libitum food conditions growth, storage of fat reserves and reproduction when kept at 5 °C versus 15 °C, and how offspring born into these conditions compensate during development to independence. Reproducing females grew less in the cold. Their lower weight resulted largely from less fat storage whereas growth in fat free mass was about the same for both groups. The increased need for thermoregulation diminished fat storage most likely due to the development of more brown fat tissue. Reproductive activity did not differ between groups in terms of litter frequency, mass and size. However, females in 5 °C weaned pups later (around day 25) than females in 15 °C (around day 21). Later weaning did not make up for the higher energy expenditure of pups in cold conditions leading to slower growth and less fat storage. Female pups born into the cold matured later than those born in 15 °C. Investment in reproduction continued but allocation to individual pups declined. CONCLUSIONS: In more thermally demanding conditions female guinea pigs - even under ad libitum food abundance - transfer the higher costs of maintenance and reproduction largely to offspring.

Concept of lipid droplet biogenesis.

Lipid droplets (LD) are functionally conserved fat storage organelles found in all cell types. LDs have a unique structure comprising of a hydrophobic core of neutral lipids (fat), triacylglycerol (TAG) and cholesterol esters (CE) surrounded by a phospholipid monolayer. LD surface is decorated by a multitude of proteins and enzymes rendering this compartment functional. Accumulating evidence suggests that LDs originate from discrete ER-subdomains, demarcated by the lipodystrophy protein seipin, however, the mechanisms of which are not well understood. LD biogenesis factors together with biophysical properties of the ER membrane orchestrate spatiotemporal regulation of LD nucleation and growth at specific ER subdomains in response to metabolic cues. Defects in LD formation manifests in several human pathologies, including obesity, lipodystrophy, ectopic fat accumulation, and insulin resistance. Here, we review recent advances in understanding the molecular events during initial stages of eukaryotic LD assembly and discuss the critical role of factors that ensure fidelity of this process.

Fatty acid metabolization and insulin regulation prevent liver injury from lipid accumulation in Himalayan marmots.

Fat storage and weight gain are dominant traits for hibernating mammals. However, excessive fat accumulation may cause liver damage. Here, we explore the lipid accumulation and metabolic processes of the Himalayan marmot (Marmota himalayana), a hibernating rodent species. We find that the unsaturated fatty acid (UFA) content in food was consistent with a large increase in the body mass of Himalayan marmots. Metagenomic analysis shows that Firmicutes Bacterium CAG:110 plays a synergistic role by synthesizing UFAs, which is demonstrated by fecal transplantation experiments, indicating that the gut microbiome promotes fat storage in Himalayan marmots for hibernation. Microscopic examination results indicate that the risk of fatty liver appears at maximum weight; however, liver function is not affected. Upregulations of UFA catabolism and insulin-like growth factor binding protein genes provide an entry point for avoiding liver injury.

Moderate intensity of static magnetic fields can alter the avoidance behavior and fat storage of Caenorhabditis elegans via serotonin.

Man-made static magnetic fields (SMFs) widely exist in human life as a physical environmental factor. However, the biological responses to moderate SMFs exposure and their underlying mechanisms are largely unknown. The present study was focused on exploring the nervous responses to moderate-intensity SMFs at 0.5 T and 1 T in Caenorhabditis elegans (C. elegans). We found that SMFs at either 0.5 T or 1 T had no statistically significant effects on the locomotor behaviors, while the 1 T magnetic field increased pharyngeal pumping. The avoidance behavior of the pathogenic Pseudomonas aeruginosa was greatly decreased in either 0.5 T or 1 T SMFs exposed nematodes, and the learning index was reducede from 0.52 ± 0.11 to 0.23 ± 0.17 and 0.16 ± 0.11, respectively. The total serotonin level was increased by 17.08% and 16.45% with the treatment of 0.5 T and 1 T SMF, compared to the control group; however, there were minimal effects of SMFs on other three neurotransmitters including choline, γ-aminobutyric acid (GABA), dopamine. RT-qPCR was used to further investigate the expression of serotonin-related genes, including rate-limiting enzymes, transcription factors and transport receptors. The expression levels of tph-1 and unc-86 genes were increased by SMF exposure, while those of ocr-2, osm-9, ser-1 and mod-1 genes were decreased. With the staining of lipid in either wild-type N2 or tph-1 mutants, we found that 0.5 T and 1 T SMFs decreased fat storage in C. elegans via serotonin pathway. Our study demonstrated that moderate-intensity SMFs induced neurobehavioral disorder and the reduction of fat storage by disturbing the secretion of serotonin in C. elegans, which provided new insights into elucidating nervous responses of C. elegans to moderate-intensity SMFs.

Enhanced lipogenesis through Pparγ helps cavefish adapt to food scarcity.

Nutrient availability varies seasonally and spatially in the wild. While many animals, such as hibernating animals or migrating birds, evolved strategies to overcome periods of nutrient scarcity,1,2 the cellular mechanisms of these strategies are poorly understood. Cave environments represent an example of nutrient-deprived environments, since the lack of sunlight and therefore primary energy production drastically diminishes the nutrient availability.3 Here, we used Astyanax mexicanus, which includes river-dwelling surface fish and cave-adapted cavefish populations, to study the genetic adaptation to nutrient limitations.4-9 We show that cavefish populations store large amounts of fat in different body regions when fed ad libitum in the lab. We found higher expression of lipogenesis genes in cavefish livers when fed the same amount of food as surface fish, suggesting an improved ability of cavefish to use lipogenesis to convert available energy into triglycerides for storage into adipose tissue.10-12 Moreover, the lipid metabolism regulator, peroxisome proliferator-activated receptor γ (Pparγ), is upregulated at both transcript and protein levels in cavefish livers. Chromatin immunoprecipitation sequencing (ChIP-seq) showed that Pparγ binds cavefish promoter regions of genes to a higher extent than surface fish and inhibiting Pparγ in vivo decreases fat accumulation in A. mexicanus. Finally, we identified nonsense mutations in per2, a known repressor of Pparγ, providing a possible regulatory mechanism of Pparγ in cavefish. Taken together, our study reveals that upregulated Pparγ promotes higher levels of lipogenesis in the liver and contributes to higher body fat accumulation in cavefish populations, an important adaptation to nutrient-limited environments.

Krüppel homolog 1 regulates photoperiodic reproductive plasticity in the cabbage beetle Colaphellus bowringi.

Many insects exhibit reproductive plasticity where the photoperiod determines whether the insect becomes reproductively active or enters diapause. Adult reproductive diapause is a strategy that allows insects to survive harsh environmental conditions. A deficiency in juvenile hormone (JH) leads to reproductive diapause. However, little is known about the molecular mechanisms by which JH signaling regulates reproductive diapause. In this study, we used the cabbage beetle Colaphellus bowringi, a serious pest, to investigate the role of Krüppel homolog 1 (Kr-h1) in controlling photoperiodic plasticity of female reproduction. We focused on Kr-h1, since it acts as a key mediator of JH signaling. We show here that JH-Methoprene-tolerant signaling upregulated the expression of Kr-h1 in reproductively active C. bowringi females when reared under short day conditions. In the long day-treated diapausing females, Kr-h1 transcripts decreased dramatically. Interfering with Kr-h1 function repressed reproductive development by blocking vitellogenesis and ovarian growth. Further, Kr-h1 depletion induced other diapause-like traits, including elevated lipid accumulation and high expression of diapause-related genes. RNA-Seq showed that Kr-h1 played both activating and repressive roles, depending on whether downstream genes were acting in reproduction- or diapause pathways, respectively. Finally, we identified the DNA replication gene mini-chromosome maintenance 4 and two triacylglycerol lipase genes as critical downstream factors of Kr-h1 that are critical for reproductive plasticity in C. bowringi. These results reveal that Kr-h1 is a key component of the regulatory pathway that coordinates reproduction and diapause in insects in response to photoperiodic input.

Fatter or stronger: Resource allocation strategy and the underlying metabolic mechanisms in amphibian tadpoles.

The allocation of resources between storage and somatic growth is an essential physiological phenomenon in animals. Allocation mechanisms have broad theoretical and applied implications. The real-time resource allocation patterns in animals remain to be elucidated, and there is limited understanding of the metabolic mechanisms. We investigated the resource allocation strategy of Rana omeimontis tadpoles. Their ontogenetic fat accumulation began when body weight increased to 30-50 mg, at which time storage had a high priority in resource allocation. Beyond this weight range, somatic growth accelerated but storage investment was maintained, resulting in a positive correlation between body fat index and body weight at the population level. This pattern could be explained by assuming a positive relationship between storage abundance and growth investment, and this was supported by the prioritized increment of body fat to body weight when tadpoles were provided with increased food. At the metabolic level, hepatic fat accumulation was accompanied by upregulated utilization of fat storage, and the tadpoles presented lipid-based energy metabolism. Activating the mobilization of hepatic fat storage promoted somatic growth. In short, the liver is like a reservoir with valves that regulate energy flow for downstream developmental processes. These results provide novel mechanistic insights into resource allocation.