211 research outputs found
DNA methylation associated with mitochondrial dysfunction in a south african autism spectrum disorder cohort
No full textAutism spectrum disorder (ASD) is characterized by phenotypic heterogeneity and a complex genetic architecture which includes distinctive epigenetic patterns. We report differential DNA methylation patterns associated with ASD in South African children. An exploratory whole‐epigenome methylation screen using the Illumina 450 K MethylationArray identified differentially methylated CpG sites between ASD and controls that mapped to 898 genes (P ≤ 0.05) which were enriched for nine canonical pathways converging on mitochondrial metabolism and protein ubiquitination. Targeted Next Generation Bisulfite Sequencing of 27 genes confirmed differential methylation between ASD and control in our cohort. DNA pyrosequencing of two of these genes, the mitochondrial enzyme Propionyl‐CoA Carboxylase subunit Beta (PCCB ) and Protocadherin Alpha 12 (PCDHA12 ), revealed a wide range of methylation levels (9–49% and 0–54%, respectively) in both ASD and controls. Three CpG loci were differentially methylated in PCCB (P ≤ 0.05), while PCDHA12 , previously linked to ASD, had two significantly different CpG sites (P ≤ 0.001) between ASD and control. Differentially methylated CpGs were hypomethylated in ASD. Metabolomic analysis of urinary organic acids revealed that three metabolites, 3‐hydroxy‐3‐methylglutaric acid (P = 0.008), 3‐methyglutaconic acid (P = 0.018), and ethylmalonic acid (P = 0.043) were significantly elevated in individuals with ASD. These metabolites are directly linked to mitochondrial respiratory chain disorders, with a putative link to PCCB , consistent with impaired mitochondrial function. Our data support an association between DNA methylation and mitochondrial dysfunction in the etiology of AS
Metabolomics reveals the depletion of intracellular metabolites in HepG2 cells after treatment with gold nanoparticles
No full textStudies on the safety of gold nanoparticles (GNPs) are plentiful due to their successful application in drug delivery and treatment of diseases in trials. Cytotoxicity caused by GNPs has been studied on the physiological and biochemical level; yet, the effect of GNPs (particularly gold nano-spheres) on the metabolome of living organisms remains understudied. In this investigation, metabolomics was used to comprehensively study the metabolic alterations in HepG2 cells caused by GNPs; and to investigate the role of representative GNP coatings. GNPs were synthesized, coated and characterized before use on HepG2 cell cultures. Cells were treated for 3 h with citrate-, poly-(sodiumsterene sulfunate)-, and poly-vinylpyrrolidone (PVP)-capped GNPs, respectively. The internalization of the different GNPs and their effect on mitochondrial respiration and the metabolome were studied. Results indicated that the PVP-capped GNPs internalized more and also caused a more observable effect on the metabolome. Conversely, it was the citrate- and poly-(sodiumsterene sulfunate) coated particles that influenced ATP production in addition to the metabolomic changes. A holistic depletion of intracellular metabolites was observed regardless of GNP coating, which hints to the binding of certain metabolites to the particle
Systemic and organ specific metabolic variation in metallothionein knockout mice challenged with swimming exercise
No full textMetallothioneins (MTs) are ubiquitous, multifunctional
proteins with key roles in metal homeostasis and
redox regulation. Their involvement in cellular energy
metabolism is evident from the observation that metallothionein-
knockout (MTKO) mice become moderately obese.
Transcriptomic studies have also indicated that several genes
associated with energy metabolism are differentially expressed
in these mice. Although single varying metabolites have
been reported, the roles of MTs on a global metabolic level
have not been investigated before. In this study, an untargeted,
hypothesis-generating metabolomics approach was
used to identify and report all metabolites that differ in relative
concentration between MT1?2KO, MT3KO and wildtype
(WT) mice before and after an exercise (1 h swim)
perturbation. PCA and univariate results confirmed that the
metabolism of the MTKO mice differs from the WT during
unchallenged conditions and hypothetically pointed to
increased anabolic activity which could contribute to their
previously reported tendency to become obese. Furthermore,
the metabolic differences observed in the liver after the 1 h
swim indicated that catabolic activity might be impaired in
these mice, which could be a consequence of a dysfunction of
a common catabolic signal. The MT3KO mice did not show
the same metabolic pattern as the MT1?2KO mice as most
metabolite concentrations in the brain of these mice were
lower after the 1 h swim. The reported metabolic variation
contributes to better understand the diverse functionality of
these ubiquitous proteins on a global phenotypic level
Abalone growth and associated aspects: now from a metabolic perspective
No full textWorldwide, there are approximately 100 Haliotis species, more commonly known as abalone or ‘Paua’ in New Zealand, ‘Venus's‐ears’ in Greece, ‘Awabi’ in Japan, ‘Perlemoen’ in South Africa and ‘Ormers’ in Europe. Regardless of what they are called in any part of the world, a high monetary value is coupled to this animal, because it is largely considered a seafood delicacy. Subsequently, a great deal of research primarily focused on improving the health and growth rates of abalone were carried out to maximise productivity of the commercial farming efforts in various countries. In this review, we comprehensively describe the most recent available scientific literature on abalone biology, and those aspects related to the growth of this organism; more specifically, those factors related to the uptake and breakdown of metabolic products which ensures long‐term growth. We subsequently discuss this in terms of basic animal design, farming outcomes, feeding, cellular growth mechanisms and the unique metabolic processes that exist in these species. Using this information and the knowledge of the metabolic processes in other organisms, we additionally make a number of new hypotheses regarding how these metabolic processes may function in terms of abalone growth. Based on the information presented in this review, we also identify major research opportunities and gaps in the existing knowledge of abalone metabolism, which when elucidated may not only serve the purpose of better understanding these organisms growth but also could potentially lead to increased productivity of the abalone commercial farming secto
Metabolic risks of neonates at birth following in utero exposure to HIV-ART: the amino acid profile of cord blood
No full textIntroduction
Untargeted metabolomics of cord blood indicated that antiretroviral therapy to HIV-infected mothers (HIV-ART) did not compromise the exposed neonates with regard to the stress of neonatal hypoglycaemia at birth. However, identified biomarkers reflected stress in their energy metabolism, raising concern over developmental risks in some newborns exposed to ART.
Objectives
This study addresses the concern over HIV-ART-induced metabolic perturbations by expanding the metabolomics study to the amino acid profiles in cord blood collected at birth from newborns either exposed or unexposed to HIV-ART in utero.
Methods
Amino acid profiles derived from liquid chromatographic triple quadruple spectra of cord blood from neonates exposed and unexposed to HIV-ART (cohort 1) were investigated using a metabolomics approach. Amino acid data, generated by ultra performance liquid chromatography–tandem mass spectrometry from similar cases (cohort 2), were included for comparison.
Results
Multivariate and supporting statistics indicated differentiation between the exposed and unexposed neonates in both cohorts, caused by a general decrease or downregulation of amino acid concentrations in the cord blood samples from the exposed cases. Specifically, significant upregulation of aspartic acid in both cohorts and downregulation of arginine, and of threonine, tryptophan and lysine in cohorts 1 and 2, respectively, were observed.
Conclusions
The benefits of ART for HIV-infected pregnant women are well established. However, the amino acid profile of cord blood, obtained from the two independent cohorts, adds to observed metabolic risks of in utero HIV-ART-exposed newborns. These risks could potentially have adverse consequences for the future health of some exposed infant
Untargeted metabolite profiling of abalone using gas chromatography mass spectrometry
No full textAbalone meat is a delicacy worldwide, fetching high prices and a valuable source of income for the many countries farming and exporting this commodity. The quality of abalone is based on its unique sensory properties and an analytical metabolomics method for determining the compounds related to this would serve as a valuable tool for ensuring quality and consumer satisfaction. Metabolomics is a promising “omics” tool which can be applied towards this goal; however, widely applicable parameters for the evaluation of an untargeted gas chromatography mass spectrometry (GC-MS) metabolomic approach is still lacking. GC-MS is a popular and suitable metabolomics method due to its high separation power, reproducible retention times, and selective mass detection. The aim of this study was to establish a reliable untargeted GC-MS method for analyzing firstly a standard compound mixture consisting of 10 compounds representing various compound classes and secondly applying the method in an untargeted manner to abalone muscle samples. Using a standard compound mixture with a concentration range of 1 to 100 μg/mL, the limit of detection (LOD) ranged between 0.01 and 3.30 μg/mL, the limit of quantification (LOQ) resulted in values between 0.02 and 9.49 μg/mL, the accuracy determined was <1.5 μg/mL, and the precision displayed a coefficient of variance (CV) <25 %. When evaluating the method in terms of biological samples harvested, the repeatability and intermediate precision showed CV values <50 % for most compounds measured, allowing application of this method for metabolite profiling of abalone to answer important biological question
Urinary metabolites and their link with premature arterial stiffness in black boys: the ASOS study
No full textBackground and Aims: Black boys (6–8 years of age) were shown to have higher pulse wave
velocity with potential early vascular compromise. We aimed to compare predefined urinary
metabolites in black and white boys to explore associations of pulse wave velocity with these
metabolites. Methods and Results: We included 40 white and 40 black apparently healthy
boys between the ages of 6 and 8 years. Femoral pulse wave velocity was measured along
with various metabolites using liquid chromatography tandem mass spectrometry (LC-MS/
MS) and gas chromatography-time of flight-mass spectrometry (GC-TOF-MS) methods. Pulse
wave velocity and diastolic blood pressure were higher in the black compared to the white
boys (both p ≤ 0.002). Isovalerylcarnitine was lower and 1-metylhistidine tended to be lower
(p = 0.002 and p = 0.073, respectively), whereas L-proline levels tended to be higher (p = 0.079)
in the black compared to the white boys. In single, partial, and multiple regression analyses,
pulse wave velocity correlated inversely with β-alanine (β = –0.414; p = 0.008) and 1-methylhistidine (β = –0.347; p = 0.032) and positively with L-proline (β = 0.420; p = 0.008), threonic
acid (β = 0.977; p = 0.033), and malonic acid (β = 0.348; p = 0.030) in black boys only. Conclusion: Our study is the first to discover the associations of pulse wave velocity with β-alanine,
1-methylhistidine, and L-proline in children from South Africa, which may suggest potential
early compromise in cardiac protective metabolic pathways in black boys as young as 6 years
of ag
Metabolomics of Ndufs4−/− skeletal muscle: adaptive mechanisms converge at the ubiquinone-cycle
No full textLeigh syndrome is one of the most common childhood-onset neurometabolic disorders resulting from a primary oxidative phosphorylation dysfunction and affecting mostly brain tissues. Ndufs4−/− mice have been widely used to study the neurological responses in this syndrome, however the reason why these animals do not display strong muscle involvement remains elusive. We combined biochemical strategies and multi-platform metabolomics to gain insight into the metabolism of both glycolytic (white quadriceps) and oxidative (soleus) skeletal muscles from Ndufs4−/− mice. Enzyme assays confirmed severely reduced (80%) CI activity in both Ndufs4−/− muscle types, compared to WTs. No significant alterations were evident in other respiratory chain enzyme activities; however, Ndufs4−/− solei displayed moderate decreases in citrate synthase (12%) and CIII (18%) activities. Through hypothesis-generating metabolic profiling, we provide the first evidence of adaptive responses to CI dysfunction involving non-classical pathways fueling the ubiquinone (Q) cycle. We report a respective 48 and 34 discriminatory metabolites between Ndufs4−/− and WT white quadriceps and soleus muscles, among which the most prominent alterations indicate the involvement of the glycerol-3-phosphate shuttle, electron transfer flavoprotein system, CII, and proline cycle in fueling the Q cycle. By restoring the electron flux to CIII via the Q cycle, these adaptive mechanisms could maintain adequate oxidative ATP production, despite CI deficiency. Taken together, our results shed light on the underlying pathogenic mechanisms of CI dysfunction in skeletal muscle. Upon further investigation, these pathways could provide novel targets for therapeutic intervention in CI deficiency and potentially lead to the development of new treatment strategie
A urinary biosignature for mitochondrial myopathy, encephalopathy, lactic acidosis and stroke like episodes (MELAS)
No full textWe used a comprehensive metabolomics approach to study the altered urinary metabolome of two mitochondrial myopathy, encephalopathy lactic acidosis and stroke like episodes (MELAS) cohorts carrying the m.3243A>G mutation.
The first cohort were used in an exploratory phase, identifying 36 metabolites that were significantly perturbed by the disease. During the second phase, the 36 selected metabolites were able to separate a validation cohort of MELAS patients completely from their respective control group, suggesting usefulness of these 36 markers as a diagnostic set. Many of the 36 perturbed metabolites could be linked to an altered redox state, fatty acid catabolism and one-carbon metabolism. However, our evidence indicates that, of all the metabolic perturbations caused by MELAS, stalled fatty acid oxidation prevailed as being particularly disturbed.
The strength of our study was the utilization of five different analytical platforms to generate the robust metabolomics data reported here. We show that urine may be a useful source for disease-specific metabolomics data, linking, amongst others, altered one-carbon metabolism to MELAS. The results reported here are important in our understanding of MELAS and might lead to better treatment options for the diseas
From untargeted LC-QTOF analysis to characterisation of opines in abalone adductor muscle: Theory meets practice
No full textAbalone have a unique ability to use pyruvate, various amino acids and dehydrogenases, to produce opines as means to prevent the accumulation of NADH during anaerobic conditions. In this study, the theoretical masses, formulae and fragment patterns of butylated opines were used to predict which of these compounds could be found in the abalone adductor muscle using untargeted liquid chromatography quadrupole time-of flight-mass spectrometry. These findings were validated using synthesised opine standards. In essence alanopine, lysopine, strombine and tauropine produced in abalone adductor muscle could be characterised using the highest identification confidence level
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