Systems biological responses to chronic perfluorododecanoic acid exposure by integrated metabonomic and transcriptomic studies

The metabolomic window into hepatobiliary disease

The emergent discipline of metabolomics has attracted considerable research effort in hepatology. Here we review the metabolomic data for non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), cirrhosis, hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), alcoholic liver disease (ALD), hepatitis B and C, cholecystitis, cholestasis, liver transplantation, and acute hepatotoxicity in animal models. A metabolomic window has permitted a view into the changing biochemistry occurring in the transitional phases between a healthy liver and hepatocellular carcinoma or cholangiocarcinoma. Whether provoked by obesity and diabetes, alcohol use or oncogenic viruses, the liver develops a core metabolomic phenotype (CMP) that involves dysregulation of bile acid and phospholipid homeostasis. The CMP commences at the transition between the healthy liver (Phase 0) and NAFLD/NASH, ALD or viral hepatitis (Phase 1). This CMP is maintained in the presence or absence of cirrhosis (Phase 2) and whether or not either HCC or CCA (Phase 3) develops. Inflammatory signalling in the liver triggers the appearance of the CMP. Many other metabolomic markers distinguish between Phases 0, 1, 2 and 3. A metabolic remodelling in HCC has been described but metabolomic data from all four Phases demonstrate that the Warburg shift from mitochondrial respiration to cytosolic glycolysis foreshadows HCC and may occur as early as Phase 1. The metabolic remodelling also involves an upregulation of fatty acid β-oxidation, also beginning in Phase 1. The storage of triglycerides in fatty liver provides high energy-yielding substrates for Phases 2 and 3 of liver pathology. The metabolomic window into hepatobiliary disease sheds new light on the systems pathology of the liver.

Metabolic phenotypes associated with high-temperature tolerance of Porphyra haitanensis strains

Colored mutants of Porphyra haitanensis have superior production and quality characteristics, with two mutants, Shengfu 1 (SF-1) and Shengfu 2 (SF-2), having good high-temperature tolerances. To understand the molecular aspects of high-temperature tolerance, this study comprehensively investigated the metabolic differences between the high-temperature tolerant strains and wild type. Nuclear magnetic resonance (NMR) methods identified 35 algal metabolites, including sugars, amino acids, carboxylic acids, aldehydes, amines, and nucleotides. The results indicated that the high-temperature tolerant strains had significantly different metabolic phenotypes from the wild type. The high-temperature tolerant mutants had significantly higher levels in a set of osmolytes consisting of betaine, taurine, laminitol, and isofloridoside than the wild type, indicating the particular importance of efficient osmoregulation for high-temperature resistance. These findings provided essential metabolic information about high-temperature adaptation for P. haitanensis and demonstrated NMR-based metabolomics as a useful tool for understanding the metabolic features related to resistance to stressors.

High-fat diet induces dynamic metabolic alterations in multiple biological matrices of rats

Obesity is a condition resulting from the interactions of individual biology and environmental factors causing multiple complications. To understand the system's metabolic changes associated with the obesity development and progression, we systematically analyzed the dynamic metabonomic changes induced by a high-fat diet (HFD) in multiple biological matrices of rats using NMR and GC-FID/MS techniques. Clinical chemistry and histopathological data were obtained as complementary information. We found that HFD intakes caused systematic metabolic changes in blood plasma, liver, and urine samples involving multiple metabolic pathways including glycolysis, TCA cycle, and gut microbiota functions together with the metabolisms of fatty acids, amino acids, choline, B-vitamins, purines, and pyrimidines. The HFD-induced metabolic variations were detectable in rat urine a week after HFD intake and showed clear dependence on the intake duration. B-vitamins and gut microbiota played important roles in the obesity development and progression together with changes in TCA cycle intermediates (citrate, α-ketoglutarate, succinate, and fumarate). 83-day HFD intakes caused significant metabolic alterations in rat liver highlighted with the enhancements in lipogenesis, lipid accumulation and lipid oxidation, suppression of glycolysis, up-regulation of gluconeogenesis and glycogenesis together with altered metabolisms of choline, amino acids and nucleotides. HFD intakes reduced the PUFA-to-MUFA ratio in both plasma and liver, indicating the HFD-induced oxidative stress. These findings provided essential biochemistry information about the dynamic metabolic responses to the development and progression of HFD-induced obesity. This study also demonstrated the combined metabonomic analysis of multiple biological matrices as a powerful approach for understanding the molecular basis of pathogenesis and disease progression.

¹H NMR and multivariate data analysis of the relationship between the age and quality of duck meat

To contribute to a better understanding of the factors affecting meat quality, we investigated the influence of age on the chemical composition of duck meat. Aging probably affects the quality of meat through changes in metabolism. Therefore, we studied the metabolic composition of duck meat using (1)H nuclear magnetic resonance (NMR) spectroscopy. Comprehensive multivariate data analysis showed significant differences between extracts from ducks that had been aged for four different time periods. Although lactate and anserine increased with age, fumarate, betaine, taurine, inosine and alkyl-substituted free amino acids decreased. These results contribute to a better understanding of changes in duck meat metabolism as meat ages, which could be used to help assess the quality of duck meat as a food.

Metabolic influence of acute cyadox exposure on Kunming mice

Cyadox is an antibiotic drug and has the potential to be used as a feedstuff additive in promoting the growth of animals. However, the toxicity of cyadox should be fully assessed before application, and this has prompted the current investigation on the metabolic responses of mice to cyadox exposure, using a metabonomic technique. Three groups of Kunming mice were respectively given a single dose of cyadox at three different concentrations (100, 650, and 4000 mg/kg body weight) via gavage. We present here the metabolic alterations of urine, plasma, liver, and renal medulla extracts induced by cyadox exposure. The metabolic alterations induced by cyadox exposure are dose-dependent, and metabolic recovery is achieved only for low and moderate levels of cyadox exposure during the experimental period. Cyadox exposure resulted in a disturbance of gut microbiota, which is manifested in depleted levels of urinary hippurate, trimethylamine-N-oxide (TMAO), dimethylamine (DMA), and trimethylamine (TMA). In addition, mice exposed to cyadox at high levels caused accumulations of amino acids and depletions of nucleotides in the liver. Furthermore, marked elevations of nucleotides and a range of organic osmolytes, such as myo-inositol, choline, and glycerophosphocholine (GPC), and decreased levels of amino acids are observed in the renal medulla of cyadox-exposed mice. These results suggest that cyadox exposure causes inhibition of amino acid metabolism in the liver and disturbance of gut microbiota community, influencing osmolytic homeostasis and nucleic acids synthesis in both the liver and the kidney. Our work provides a comprehensive view of the toxicological effects of cyadox, which is important in animal and human food safety.

Responses of mouse liver to dechlorane plus exposure by integrative transcriptomic and metabonomic studies

Dechlorane plus (DP), a chlorinated flame retardant, has been widely detected in different environmental matrices and biota. However, toxicity data for DP have seldom been reported. In the present study, we investigated hepatic oxidative stress, DNA damage, and transcriptomic and metabonomic responses of male mice administered 500 mg/kg, 2000 mg/kg, and 5000 mg/kg of DP by gavage for 10 days. The results showed that DP exposure increased the level of superoxide dismutase (SOD) and 8-hydroxy-2-deoxyguanosine (8-OHdG). The microarray-based transcriptomic results demonstrated that DP exposure led to significant alteration of gene expression involved in carbohydrate, lipid, nucleotide, and energy metabolism, as well as signal transduction processes. The NMR-based metabonomic analyses corroborated these results showing changes of metabolites associated with the above altered mechanisms. Our results demonstrate that an oral exposure to DP can induce hepatic oxidative damage and perturbations of metabolism and signal transduction. These observations provide novel insight into toxicological effects and mechanisms of action of DP at the transcriptomic and metabonomic levels.

Systems responses of rats to mequindox revealed by metabolic and transcriptomic profiling

Mequindox is used as an antibiotic drug in livestock; however, its toxicity remains largely unclear. Previously, we investigated metabolic responses of mice to mequindox exposure. In order to evaluate dependences of animal species in response to mequindox insult, we present the metabolic consequences of mequindox exposure in a rat model, by employing the combination of metabonomics and transcriptomics. Metabolic profiling of urine revealed that metabolic recovery is achieved for rats exposed to a low or moderate dose of mequindox, whereas high levels of mequindox exposure trigger liver dysfunction, causing no such recovery. We found that mequindox exposure causes suppression of the tricarboxylic acid cycle and stimulation of glycolysis, which is in contrast to a mouse model previously investigated. In addition, mequindox dosage induces promotion of β-oxidation of fatty acids, which was confirmed by elevated expressions of acox1, hsd17b2, and cpt1a in liver. Furthermore, altered levels of N-methylnicotinate, 1-methylnicotinamide, and glutathione disulfide highlighted the promotion of vitamin B3 antioxidative cycle in rats exposed to mequindox. Moreover, mequindox exposure altered levels of gut microbiotal related co-metabolites, suggesting a perturbation of the gut microflora of the host. Our work provides a comprehensive view of the toxicological effects of mequindox, which is important in the usage of mequindox in animal and human food safety.

Eliminating the dication-induced intersample chemical-shift variations for NMR-based biofluid metabonomic analysis

NMR-based urinary metabonomic analysis is an essential aspect of systems biology for understanding mammalian physiology and pathophysiology though intersample chemical-shift variations can cause serious problems. Here, we report two optimized and validated methods to eliminate such variations resulting from intersample differences in pH and dication concentration. We found that the Ca(2+) concentration was 7.41 ± 3.48, 1.03 ± 0.34 and 0.87 ± 0.52 mM whereas the Mg(2+) concentration was 3.02 ± 1.41, 2.65 ± 1.20 and 0.80 ± 0.59 mM in rat, mouse and human urine samples, respectively; urinary Ca-EDTA, Mg-EDTA and free EDTA had spin-lattice relaxation time values (600.13 MHz) of 0.38, 0.41 and 0.55 s, respectively. We also found that the combined treatments with potassium fluoride, phosphate buffer and a small amount of K(3)EDTA eliminated intersample chemical-shift variations for all metabolites. EDTA treatment followed with phosphate buffer also achieved similar results although resonances from EDTA and its complexes obscured some metabolite signals. We systematically optimized the amount of additives for rat, mouse and human urine samples taking into consideration the pH control, signal-to-noise ratio and intersample uniformity for metabolite chemical-shifts. Based on thorough validation, we established some optimized procedures for rat, mouse and human urine, respectively. By eliminating both pH and dication effects, these methods enable the reduction of intersample chemical-shift variations to 1.5 Hz for all metabolites. The methods will offer ensured data quality for high-throughput, especially robotic urinary metabonomics studies with no need for peak alignments or corrections.

Unraveling the concentration-dependent metabolic response of Pseudomonas sp. HF-1 to nicotine stress by ¹H NMR-based metabolomics

Nicotine can cause oxidative damage to organisms; however, some bacteria, for example Pseudomonas sp. HF-1, are resistant to such oxidative stress. In the present study, we analyzed the concentration-dependent metabolic response of Pseudomonas sp. HF-1 to nicotine stress using ¹H NMR spectroscopy coupled with multivariate data analysis. We found that the dominant metabolites in Pseudomonas sp. HF-1 were eight aliphatic organic acids, six amino acids, three sugars and 11 nucleotides. After 18 h of cultivation, 1 g/L nicotine caused significant elevation of sugar (glucose, trehalose and maltose), succinate and nucleic acid metabolites (cytidine, 5'-CMP, guanine 2',3'-cyclic phosphate and adenosine 2',3'-cyclic phosphate), but decrease of glutamate, putrescine, pyrimidine, 2-propanol, diethyl ether and acetamide levels. Similar metabolomic changes were induced by 2 g/L nicotine, except that no significant change in trehalose, 5'-UMP levels and diethyl ether were found. However, 3 g/L nicotine led to a significant elevation in the two sugars (trehalose and maltose) levels and decrease in the levels of glutamate, putrescine, pyrimidine and 2-propanol. Our findings indicated that nicotine resulted in the enhanced nucleotide biosynthesis, decreased glucose catabolism, elevated succinate accumulation, severe disturbance in osmoregulation and complex antioxidant strategy. And a further increase of nicotine level was a critical threshold value that triggered the change of metabolic flow in Pseudomonas sp. HF-1. These findings revealed the comprehensive insights into the metabolic response of nicotine-degrading bacteria to nicotine-induced oxidative toxicity.

Potential role of metabolomic approaches for Chinese medicine syndromes and herbal medicine

Systems biology has significantly increased in recent years. Its method and design resemble those of traditional Chinese medicine (TCM), which is a unique medical system that assisted the ancient Chinese in dealing with disease. The technology platforms of systems biology, especially metabolomics, could provide more rapid, direct, concise and effective methods for disease research. In particular, metabolomics could provide useful tools for exploring the essence of Chinese medicine syndromes (CMS) disease, facilitating personalized TCM. Moreover, metabolomics has the potential to enable mapping of early biochemical changes in disease and hence provide an opportunity to develop predictive biomarkers that can trigger earlier interventions. A future hope for the metabonomic approach is the identification of biomarkers that are able to highlight individuals likely to suffer from disease and enable early diagnosis of the disease or the identification of those at risk, and it will help to understand CMS and modernize TCM. In this review, we focus on the key role of robust metabolomic approaches as an aid for traditional herbal medicine; particular attention will be paid to the past successes in applications of metabonomics to contribute to low-molecular-weight metabolites (biomarkers) discovery in TCM research.

Evaluating the transcriptomic and metabolic profile of mice exposed to source drinking water

Transcriptomic and metabonomic methods were used to investigate mice's responses to drinking source water (DSW) exposure. After mice were fed with DSW for 90 days, hepatic transcriptome was characterized by microarray and serum metabonome were determined by (1)H nuclear magnetic resonance (NMR) spectroscopy. A total of 243 differentially expressed genes (DEGs) were identified, among which 141 genes were up-regulated and 102 genes were down-regulated. Metabonomics revealed significant changes in concentrations of creatine, pyruvate, glutamine, lysine, choline, acetate, lipids, taurine, and trimethylamine oxide. Four biological pathways were identified by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis where both gene expression and metabolite concentrations were altered in response to DSW exposure. These results highlight the significance of combined use of transcriptomic and metabonomic approaches in evaluating potential health risk induced by DSW contaminated with various hazardous materials.

A metabonomic analysis on health effects of drinking water on male mice (Mus musculus)

Health effects of drinking water on the male mice (Mus musculus) were investigated by metabonomics after exposure to the Taihu drinking water for 90 days. Metabonomics data combined with the results of conventional serum biochemistry tests and hepatic histopathology showed that the drinking water induced adverse health effects on the male mice. It was found that the serum levels of pyruvate, glutamine, arginine, lysine, N-acetyl glycoproteins, choline and citrate were significantly decreased in the treatment group. These results indicated that Taihu drinking water may induce damages on mice liver via perturbations of energy metabolism, amino acid metabolism and apoptosis. These observations yielded novel insights regarding the environmental health risk of Taihu drinking water.

Biological responses to perfluorododecanoic acid exposure in rat kidneys as determined by integrated proteomic and metabonomic studies

Background

Perfluorododecanoic acid (PFDoA) is a perfluorinated carboxylic chemical (PFC) that has broad applications and distribution in the environment. While many studies have focused on hepatotoxicity, immunotoxicity, and reproductive toxicity of PFCAs, few have investigated renal toxicity.

Methodology/Principal Findings

Here, we used comparative proteomic and metabonomic technologies to provide a global perspective on renal response to PFDoA. Male rats were exposed to 0, 0.05, 0.2, and 0.5 mg/kg/day of PFDoA for 110 days. After 2-D DIGE and MALDI TOF/TOF analysis, 79 differentially expressed proteins between the control and the PFDoA treated rats (0.2 and 0.5 mg-dosed groups) were successfully identified. These proteins were mainly involved in amino acid metabolism, the tricarboxylic acid cycle, gluconeogenesis, glycolysis, electron transport, and stress response. Nuclear magnetic resonance-based metabonomic analysis showed an increase in pyruvate, lactate, acetate, choline, and a variety of amino acids in the highest dose group. Furthermore, the profiles of free amino acids in the PFDoA treated groups were investigated quantitatively by high-coverage quantitative iTRAQ-LC MS/MS, which showed levels of sarcosine, asparagine, histidine, 1-methylhistidine, Ile, Leu, Val, Trp, Tyr, Phe, Cys, and Met increased markedly in the 0.5 mg dosed group, while homocitrulline, α-aminoadipic acid, β-alanine, and cystathionine decreased.

Conclusion/Significance

These observations provide evidence that disorders in glucose and amino acid metabolism may contribute to PFDoA nephrotoxicity. Additionally, α_2u globulin may play an important role in protecting the kidneys from PFDoA toxicity.

Comparison of serum metabolite compositions between obese and lean growing pigs using an NMR-based metabonomic approach

Childhood obesity has become a prevalent risk to health of children and teenagers. To develop biomarkers in serum for altered lipid metabolism, genetically obese (Ningxiang strain) and lean (Duroc×Landrace×Large Yorkshire strain) growing pigs were used as models to identify potential differences in the serum metabonome between the two strains of pigs after consuming the same diet for 46 days. At the end of the study, pigs were euthanized for analysis of the serum metabonome and determination of body composition. Obese pigs had higher fat mass (42.3±8.8% vs. 21.9±4.5%) and lower muscle mass (35.4±4.5% vs. 58.9±2.5%) than lean pigs (P<.01). Serum concentrations of insulin and glucagon were higher (P<.02) in obese than in lean pigs. With the use of an NMR-based metabonomic technology, orthogonal projection to latent structure with discriminant analysis showed that serum HDL, VLDL, lipids, unsaturated lipids, glycoprotein, myo-inositol, pyruvate, threonine, tyrosine and creatine were higher in obese than in lean pigs (P<.05), while serum glucose and urea were lower in obese pigs (P<.05). In addition, changes in gut microbiota-related metabolites, including trimethylamine-N-oxide and choline, were observed in sera of obese pigs relatively to lean pigs (P<.05). These novel findings indicate that obese pigs have distinct metabolism, including lipogenesis, lipid oxidation, energy utilization and partition, protein and amino acid metabolism, and fermentation of gastrointestinal microbes, compared with lean pigs. The obese Ningxiang pig may be a useful model for childhood obesity research.

Metabolic profiles in serum of mouse after chronic exposure to drinking water

The toxicity of Nanjing drinking water on mouse (Mus musculus) was detected by 1H nuclear magnetic resonance (NMR)-based metabonomic method. Three groups of mice were fed with drinking water (produced by Nanjing BHK Water Plant), 3.8 μg/L benzo(a)pyrene as contrast, and clean water as control, respectively, for 90 days. It was observed that the levels of lactate, alanine, and creatinine in the mice fed with drinking water were increased and that of valine was decreased. The mice of drinking water group were successfully separated from control. The total concentrations of polycyclic aromatic hydrocarbons (PAHs), phthalates (PAEs), and other organic pollutants in the drinking water were 0.23 μg/L, 4.57 μg/L, and 0.34 μg/L, respectively. In this study, Nanjing drinking water was found to induce distinct perturbations of metabolic profiles on mouse including disorders of glucose-alanine cycle, branched-chain amino acid and energy metabolism, and dysfunction of kidney. This study suggests that metabonomic method is feasible and sensitive to evaluate potential toxic effects of drinking water.

Systems responses of rats to aflatoxin B1 exposure revealed with metabonomic changes in multiple biological matrices

Exposure to aflatoxins causes liver fibrosis and hepatocellular carcinoma posing a significant health risk for human populations and livestock. To understand the mammalian systems responses to aflatoxin-B1 (AFB1) exposure, we analyzed the AFB1-induced metabonomic changes in multiple biological matrices (plasma, urine, and liver) of rats using (1)H NMR spectroscopy together with clinical biochemistry and histopathologic assessments. We found that AFB1 exposure caused significant elevation of glucose, amino acids, and choline metabolites (choline, phosphocholine, and glycerophosphocholine) in plasma but reduction of plasma lipids. AFB1 also induced elevation of liver lipids, amino acids (tyrosine, histidine, phenylalanine, leucine, isoleucine, and valine), choline, and nucleic acid metabolites (inosine, adenosine, and uridine) together with reduction of hepatic glycogen and glucose. AFB1 further caused decreases in urinary TCA cycle intermediates (2-oxoglutarate and citrate) and elevation of gut microbiota cometabolites (phenylacetylglycine and hippurate). These indicated that AFB1 exposure caused hepatic steatosis accompanied with widespread metabolic changes including lipid and cell membrane metabolisms, protein biosynthesis, glycolysis, TCA cycle, and gut microbiota functions. This implied that AFB1 exposure probably caused oxidative-stress-mediated impairments of mitochondria functions. These findings provide an overview of biochemical consequences of AFB1 exposure and comprehensive insights into the metabolic aspects of AFB1-induced hepatotoxicity in rats.

Tributyltin toxicity in abalone (Haliotis diversicolor supertexta) assessed by antioxidant enzyme activity, metabolic response, and histopathology

A toxicity test was performed to investigate the possible harmful effects of tributyltin (TBT) on abalone (Haliotis diversicolor supertexta). Animals were exposed to TBT in a range of environmentally relevant concentrations (2, 10 and 50 ng/L) for 30 days under laboratory conditions. TBT-free conditions were used as control treatments. The activity of antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD), and malondialdehyde (MDA), along with levels of haemolymph metabolites, and hepatopancreas histopathology were analyzed. The results showed that TBT decreased SOD activity, and increased POD level and MDA production in a dose-dependent way, indicating that oxidative injury was induced by TBT. Haemolymph metabolite measurements showed that TBT increased alanine and glutamate levels, and decreased glucose content, which suggested perturbation of energy metabolism. Elevated levels of acetate and pyruvate in the haemolymph indicated partial alteration of lipid metabolism. A decrease in lactate and an increase in succinate, an intermediate of the tricarboxylic acid (TCA) cycle, indicated disturbance of amino acid metabolism. Hepatopancreas tissues also exhibited inflammatory responses characterized by histopathological changes such as cell swelling, granular degeneration, and inflammation. Taken together, these results demonstrated that TBT was a potential toxin with a variety of deleterious effects on abalone.

Revealing different systems responses to brown planthopper infestation for pest susceptible and resistant rice plants with the combined metabonomic and gene-expression analysis

Brown planthopper (BPH) is a notorious pest of rice plants attacking leaf sheaths and seriously affecting global rice production. However, how rice plants respond against BPH remains to be fully understood. To understand systems metabolic responses of rice plants to BPH infestation, we analyzed BPH-induced metabolic changes in leaf sheaths of both BPH-susceptible and resistant rice varieties using NMR-based metabonomics and measured expression changes of 10 relevant genes using quantitative real-time PCR. Our results showed that rice metabonome was dominated by more than 30 metabolites including sugars, organic acids, amino acids, and choline metabolites. BPH infestation caused profound metabolic changes for both BPH-susceptible and resistant rice plants involving transamination, GABA shunt, TCA cycle, gluconeogenesis/glycolysis, pentose phosphate pathway, and secondary metabolisms. BPH infestation caused more drastic overall metabolic changes for BPH-susceptible variety and more marked up-regulations for key genes regulating GABA shunt and biosynthesis of secondary metabolites for BPH-resistant variety. Such observations indicated that activation of GABA shunt and shikimate-mediated secondary metabolisms was vital for rice plants to resist BPH infestation. These findings filled the gap of our understandings in the mechanistic aspects of BPH resistance for rice plants and demonstrated the combined metabonomic and qRT-PCR analysis as an effective approach for understanding plant-herbivore interactions.

Metabolic changes reveal the development of schistosomiasis in mice

Schistosomiasis is a parasitic zoonosis caused by small trematode worms called schistosomes, amongst which Schistosoma japonicum (S. japonicum) is endemic in Asia. In order to understand the schistosome-induced changes in the host metabolism so as to facilitate early diagnosis of schistosomiasis, we systematically investigated the dynamic metabolic responses of mice biofluids and liver tissues to S. japonicum infection for five weeks using ¹H NMR spectroscopy in conjunction with multivariate data analysis. We were able to detect schistosomiasis at the third week post-infection, which was one week earlier than “gold standard” methods. We found that S. japonicum infection caused significant elevation of urinary 3-ureidopropionate, a uracil catabolic product, and disturbance of lipid metabolism, stimulation of glycolysis, depression of tricarboxylic acid cycle and disruption of gut microbiota regulations. We further found that the changes of 3-ureidopropionate and overall metabolic changes in both urinary and plasma samples were closely correlated with the time-course of disease progression. Furthermore, such changes together with liver tissue metabonome were clearly associated with the worm-burdens. These findings provided more insightful understandings of host biological responses to the infection and demonstrated that metabonomic analysis is potentially useful for early detection of schistosomiasis and comprehension of the mechanistic aspects of disease progression.

Schistosomiasis is an infectious disease resulting from the infection of parasitic trematode worms called schistosomes. About 600 million people are currently exposed to schistosomiasis and 200 million people are infected in about 76 countries. Current diagnostic methods are unable to detect schistosomiasis at its early stages and thus are incapable of preventing disease causing further complications. In order to understand the effects of schistosome infection on hosts' biochemistry associated with disease progression in a holistic fashion and detect the infection at the early stage, we systematically investigated the metabolite composition (metabonome) changes in mice biofluids and liver tissues induced by Schistosoma japonicum using NMR spectroscopy. We detected infection-induced mice metabonomic alterations at three weeks post-infection, a week earlier than traditional methods. We found that the infection-caused elevation of urinary 3-ureidopropionate was not only associated with disease progression but also worm burden. We further found that overall metabonomic changes were also closely associated with disease progression, and our methods were capable of distinguishing different levels of worm burden at week five post-infection. Our findings provided further understandings in host responses to the infection and demonstrated metabonomics as a potentially useful tool for early diagnosis of S. japonicum infections.

An optimised sample preparation method for NMR-based faecal metabonomic analysis

Faecal metabonomic NMR analysis plays an essential role in investigating the interactions between mammalian metabolism and symbiotic gut microbiota. However, the faecal metabolite extraction method remains to be optimised and standardised to take into consideration signal-to-noise ratios, pH and chemical shift consistency. In the current investigation, we compared extraction consistency of three homogenisation methods including manual ultrasonication, automatic homogenization with tissuelyser and their combination, and systematically optimised faecal metabolite extraction parameters, including the faeces-to-buffer ratio (W(f) : V(b)), extraction repetition times and duration. We found that automatic homogenisation with tissuelyser was the choice of extraction method owning to its good metabolite extraction consistency and high throughput. We also recommend W(f) : V(b) of 1 : 10 (mg microl(-1)) and use of the combined first two extracts as the resultant samples to represent faecal metabolite composition. Such recommendation is based on considerations of maximisation of the spectral signal-to-noise ratio, pH and chemical shift consistency, completeness of metabolite extraction and sample preparation throughput so that the method is suitable for analysing a large number of samples especially in human population studies.

The identification of apolipoprotein genes in rare minnow (Gobiocypris rarus) and their expression following perfluorooctanoic acid exposure

Apolipoproteins play important roles in lipid transport and uptake in vertebrates, and they are associated with pathogenesis of many cardiovascular diseases. However, the diverse apolipoproteins in individual fish species have not been extensively characterized. Partial cDNA sequences encoding ApoA-IV, ApoE, ApoM, ApoL, and ApoO, and full-length cDNA sequences encoding ApoA-I were cloned from rare minnow (Gobiocypris rarus). Sequence analysis showed that these genes, as well as fragments of other known apolipoprotein genes (ApoC-I, ApoC-II, ApoB) of rare minnow had a high similarity (91-96%) to their orthologues in the spotted barbel Hemibarbus mylodon (Teleostei:Cypriniformes). The expression of these nine genes and their possible upstream genes, PPARalpha, PPARgamma, and HNF4alpha, were investigated in rare minnow after subacute exposure to perfluorooctanoic acid (PFOA) for 14days. Results showed that the expression of mRNA for ApoA-I, ApoC-II, and ApoM was significantly downregulated in all PFOA-treated animals. Only fish receiving the highest dose of PFOA showed downregulation of the expression of ApoA-IV and ApoC-I, while fish treated with 10mg PFOA/L showed upregulation of expression of ApoE. Expression of ApoB, ApoO, and ApoL was unchanged between control and treated groups. In addition, the expression of PPARalpha was increased in all dosed fish, while the mRNAs for PPARgamma and HNF4alpha were significantly altered with 30 and 3mg PFOA/L doses, respectively. Therefore, subacute exposure to PFOA resulted in alteration of expression of apolipoproteins and related genes. These changes in gene expression may further influence lipid metabolism or other physiological functions in fish.