Peet Jansen van Rensburg

Earthworm (Eisenia Fetida) bioassay to assess the possible effects of platinum tailings disposal facilities on the environment along a gradient

Platinum mines produce large amounts of inorganic tailings containing high levels of metals which are disposed of on tailings disposal facilities (TDFs) and there is no information available on their possible effects on the surrounding terrestrial environment. The aim of this study was to do an earthworm bioassay of soils along a gradient from a TDF over a period of 28 days in terms of growth, reproduction and metal accumulation. After 28 days the earthworms in the soil collected up to 1 km away from the TDF showed a significant (P < 0.05) decrease in bodyweight and in the soil 2−5 km away showed no effect. The earthworms in the soil collected 15 km away from the TDF showed a significant (P < 0.05) increase in bodyweight. The mean hatching success of cocoons was significantly (P < 0.05) higher in the soils further away from the TDF viz. 15 km > 3−5 km > 2−0 km. Cr, Cu, Ni and Zn concentrations in the soils collected in the soils on the platinum TDF (TDF − 15 km in the case of Zn) were higher, while Cd, Co and Pb were lower when compared to screening benchmarks proposed by the U.S. Dept. of Energy. The presence of these metals in a mixture, however, makes it extremely difficult to assess their effects. All of the metals had low bioconcentration factors (BCFs) viz. < 0.01 (CR, Ni and Pb), 0.01 (Co), 0.33−0.5 (Cd), 0.01−0.08 (Cu) and 0.18−0.29 (Zn). It can be concluded that platinum mining, with TDFs as source of contamination, has negative effects on the environment but further studies are needed to assess the exact extent of these effects.

Untargeted urine metabolomics reveals a biosignature for muscle respiratory chain deficiencies

Mitochondrial diseases are a heterogeneous group of disorders characterised by impaired mitochondrial oxidative phosphorylation system. Most often for mitochondrial disease, where no metabolic diagnostic biomarkers exist, a deficiency is diagnosed after analysing the respiratory chain enzymes (complexes I-IV) in affected tissues or by identifying one of an ever expanding number of DNA mutations. This presents a great challenge to identify cases to undergo the invasive diagnostic procedures required. An untargeted liquid chromatography mass spectrometry metabolomics approach was used to search for a metabolic biosignature that can distinguish respiratory chain deficient (RCD) patients from clinical controls (CC). A cohort of 37 ethnically diverse cases was used. Sample preparation, liquid chromatography time-of-flight mass spectrometry methods and data processing methods were standardised. Furthermore the developed methodology used reverse phase chromatography in conjunction with positive electrospray ionisation and hydrophilic interaction chromatography with negative electrospray ionisation. Urine samples of 37 patients representing two different experimental groups were analysed. The two experimental groups comprised of patients with confirmed RCDs and CC. After a variety of data mining steps and statistical analyses a list of 12 features were compiled with the ability to distinguish between patients with RCDs and CC. Although the features of the biosignature needs to be identified and the biosignature validated, this study demonstrates the value of untargeted metabolomics to identify a metabolic biosignature to possibly be applied in the selection criteria for RCDs.

Increased Excretion of C4-Carnitine Species after a Therapeutic Acetylsalicylic Acid Dose: Evidence for an Inhibitory Effect on Short-Chain Fatty Acid Metabolism

Acetylsalicylic acid and/or its metabolites are implicated to have various effects on metabolism and, especially, on mitochondrial function. These effects include both inhibitory and stimulatory effects. We investigated the effect of both combined and separate oral acetylsalicylic acid and acetaminophen administration at therapeutic doses on the urinary metabolite profile of human subjects. In this paper, we provided in vivo evidence, in human subjects, of a statistically significant increase in isobutyrylcarnitine after the administration of a therapeutic dose of acetylsalicylic acid. We, therefore, propose an inhibitory effect of acetylsalicylic acid on the short-chain fatty acid metabolism, possibly at the level of isobutyryl-CoA dehydrogenase.

From untargeted LC-QTOF analysis to characterisation of opines in abalone adductor muscle: theory meets practice

Abalone 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 levels.

Foraging at wastewater treatment works affects brown adipose tissue fatty acid profiles in banana bats

ABSTRACT In this study we tested the hypothesis that the decrease in habitat quality at wastewater treatment works (WWTW), such as limited prey diversity and exposure to the toxic cocktail of pollutants, affect fatty acid profiles of interscapular brown adipose tissue (iBrAT) in bats. Further, the antioxidant capacity of oxidative tissues such as pectoral and cardiac muscle may not be adequate to protect those tissues against reactive molecules resulting from polyunsaturated fatty acid auto-oxidation in the WWTW bats. Bats were sampled at two urban WWTW, and two unpolluted reference sites in KwaZulu-Natal, South Africa. Brown adipose tissue (BrAT) mass was lower in WWTW bats than in reference site bats. We found lower levels of saturated phospholipid fatty acids and higher levels of mono- and polyunsaturated fatty acids in WWTW bats than in reference site bats, while C18 desaturation and n-6 to n-3 ratios were higher in the WWTW bats. This was not associated with high lipid peroxidation levels in pectoral and cardiac muscle. Combined, these results indicate that WWTW bats rely on iBrAT as an energy source, and opportunistic foraging on abundant, pollutant-tolerant prey may change fatty acid profiles in their tissue, with possible effects on mitochondrial functioning, torpor and energy usage. Summary: Brown adipose tissue of banana bats foraging at wastewater treatment works contained lower saturated and higher mono- and polyunsaturated phospholipid fatty acids than that of bats foraging at reference sites.

The cross-tissue metabolic response of abalone (Haliotis midae) to functional hypoxia

ABSTRACT Functional hypoxia is a stress condition caused by the abalone itself as a result of increased muscle activity, which generally necessitates the employment of anaerobic metabolism if the activity is sustained for prolonged periods. With that being said, abalone are highly reliant on anaerobic metabolism to provide partial compensation for energy production during oxygen-deprived episodes. However, current knowledge on the holistic metabolic response for energy metabolism during functional hypoxia, and the contribution of different metabolic pathways and various abalone tissues towards the overall accumulation of anaerobic end-products in abalone are scarce. Metabolomics analysis of adductor muscle, foot muscle, left gill, right gill, haemolymph and epipodial tissue samples indicated that South African abalone (Haliotis midae) subjected to functional hypoxia utilises predominantly anaerobic metabolism, and depends on all of the main metabolite classes (proteins, carbohydrates and lipids) for energy supply. Functional hypoxia caused increased levels of anaerobic end-products: lactate, alanopine, tauropine, succinate and alanine. Also, elevation in arginine levels was detected, confirming that abalone use phosphoarginine to generate energy during functional hypoxia. Different tissues showed varied metabolic responses to hypoxia, with functional hypoxia showing excessive changes in the adductor muscle and gills. From this metabolomics investigation, it becomes evident that abalone are metabolically able to produce sufficient amounts of energy when functional hypoxia is experienced. Also, tissue interplay enables the adjustment of H. midae energy requirements as their metabolism shifts from aerobic to anaerobic respiration during functional hypoxia. This article has an associated First Person interview with the first author of the paper. Summary: We report, for the first time, a metabolic map of abalone metabolism in response to functional hypoxia, compiled from results obtained by metabolomics analysis.

Gill damage, metallothionein gene expression and metal accumulation in Tilapia sparrmanii from selected field sites at Rustenburg and Potchefstroom, South Africa

Fish were collected from field sites in the mining and agricultural areas of Potchefstroom and Rustenburg, North-West Province, South Africa. Water and sediment samples from each site, together with fish muscle and gills, were analysed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for Li, Na, Mg, Al, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Hg, Pb and U. All metal levels were within the levels set by the South African Department of Water Affairs and Forestry, except for copper, which was still within the levels set by other guidelines. Water hardness, pH, dissolved oxygen concentration and conductivity were measured at each site. Fish gills were analysed morphometrically for arithmetic mean epithelial thickness (Har) and with Reverse Transcriptase PCR for metallothionein (MT) gene expression levels. Fish liver was also analysed for MT expression. Har was found to increase with changing copper levels in gills of fish, while gill and liver MT levels corresponded to changes in sediment and gill cadmium levels, respectively. There were highly significant differences in Har between different sampling sites, while no significant differences in gill and liver MT expression were found.

Uncovering the metabolic response of abalone (Haliotis midae) to environmental hypoxia through metabolomics

IntroductionOxygen is essential for metabolic processes and in the absence thereof alternative metabolic pathways are required for energy production, as seen in marine invertebrates like abalone. Even though hypoxia has been responsible for significant losses to the aquaculture industry, the overall metabolic adaptations of abalone in response to environmental hypoxia are as yet, not fully elucidated.ObjectiveTo use a multiplatform metabolomics approach to characterize the metabolic changes associated with energy production in abalone (Haliotis midae) when exposed to environmental hypoxia.MethodsMetabolomics analysis of abalone adductor and foot muscle, left and right gill, hemolymph, and epipodial tissue samples were conducted using a multiplatform approach, which included untargeted NMR spectroscopy, untargeted and targeted LC–MS spectrometry, and untargeted and semi-targeted GC-MS spectrometric analyses.ResultsIncreased levels of anaerobic end-products specific to marine animals were found which include alanopine, strombine, tauropine and octopine. These were accompanied by elevated lactate, succinate and arginine, of which the latter is a product of phosphoarginine breakdown in abalone. Primarily amino acid metabolism was affected, with carbohydrate and lipid metabolism assisting with anaerobic energy production to a lesser extent. Different tissues showed varied metabolic responses to hypoxia, with the largest metabolic changes in the adductor muscle.ConclusionsFrom this investigation, it becomes evident that abalone have well-developed (yet understudied) metabolic mechanisms for surviving hypoxic periods. Furthermore, metabolomics serves as a powerful tool for investigating the altered metabolic processes in abalone.

Bacillus-based bionematicides: development, modes of action and commercialisation

ABSTRACT Agricultural crops are severely damaged by root-knot nematodes causing extensive financial losses globally. Historically, agrochemicals have been the preferred method to combat these pests; however, threats to humans and the environment posed by these agrochemicals led to the need for developing new biocontrol agents. Importantly, the latter should adhere to biosafety regulations while being highly effective. Root-knot nematodes live in soil and thus the use of rhizobacteria such as Bacillus for biocontrol development have shown potential. Although various Bacillus species have been tested in this capacity, little is known about their secondary metabolites and the mechanisms of action responsible for their nematicidal activity. If these secondary metabolites can be qualitatively and quantitatively characterised, metabolic features could be synthetically engineered and used to combat root-knot nematodes. Although there is great potential for bionematicides, the commercialisation and development of such products can be difficult. This review summarises the importance of Bacillus species as natural antagonists of root-knot nematodes through the production of secondary metabolites. It provides an overview of the significance of root-knot nematodes in agriculture and the advances of chemical nematicides in recent years. The potential of Bacillus species as biocontrol agents, the known mechanisms of action responsible for the nematicidal activity demonstrated by Bacillus species, non-target effects of biocontrol agents and the commercialisation of Bacillus-based bionematicides are discussed.

Molecular Similarity between Gibberellic Acid and Gliotoxin: Unravelling the Mechanism of Action for Plant Growth Promotion by Trichoderma harzianum

Besides control of the fungal plant pathogens, another interesting aspect observed when plants are treated with Trichoderma harzianum include effects such as complete and even stand of plants, improved seed germination, increases in plant height and overall enhanced plant growth. No research has yet been conducted to elucidate the mechanism by which these effects occur. Improved seed germination, in particular, suggest that Trichoderma harzianum produces a metabolite that may mimic the plant growth hormone gibberellic acid. The metabolite gliotoxin, produced by Trichoderma harzianum appear to be structurally most similar to gibberellic acid. In this study, common pharmacophore generation and molecular ligand docking simulations were used to evaluate the molecular similarity between gibberellic acid, specifically GA3, and gliotoxin. For the common pharmacophore evaluation, the structure of various gibberellic acids were used to construct a pharmacophore space to which gliotoxin was aligned, and during the molecular docking simulations the gibberellic acid receptor, GID1, served as ligand target for GA3 and gliotoxin. During the common pharmacophore evaluation, gliotoxin was successfully aligned to the common pharmacophore model constructed from various gibberellic acids. Furthermore, molecular docking simulations of gliotoxin and GA3 into the gibberellic acid receptor (GID1) yielded docking scores of -10.78 kcal/mol for the GA3 molecule from Corina and a docking score of -10.17 kcal/mol for gliotoxin. The docking scores suggest that gliotoxin may be able to competitively occupy the receptor space for gibberellic acid, and as such elicit the similar physiological responses observed in literature.