Ammonium Removal in Aquaponics Indicates Participation of Comammox Nitrospira.

Aquaponic systems are sustainable solutions for food production combining fish growth (aquaculture) and production of vegetables (hydroponic) in one recirculating system. In aquaponics, nitrogen-enriched wastewater from fish in the aquaculture serves as fertilizer for the plants in the hydroponics, while the nitrogen-depleted and detoxified water flows back to the aquaculture. To investigate bacterial nitrogen-cycling in such an aquaponic system, measurements of nitrogen species were coupled with time-resolved 16S rRNA gene profiling and the functional capacity of organisms was studied using metagenomics. The aquaponic system was consistently removing ammonia and nitrite below 23 µM and 19 µM, and nitrate to steady-state concentrations of about 0.5 mM. 16S rRNA gene amplicon sequencing of sediments exposed in the pump sump revealed that typical signatures of canonical ammonia-oxidising microorganisms were below detection limit. However, one of the most abundant operational taxonomic units (OTU) was classified as a member of the genus Nitrospira with a relative abundance of 3.8%. For this genus, also genome scaffolds were recovered encoding the only ammonia monooxygenase genes identified in the metagenome. This study indicates that even in highly efficient aquaponic systems, comammox Nitrospira were found to participate in ammonium removal at low steady-state ammonia concentrations.

Protective Effects of Early Caffeine Administration in Hyperoxia-Induced Neurotoxicity in the Juvenile Rat.

High-risk preterm infants are affected by a higher incidence of cognitive developmental deficits due to the unavoidable risk factor of oxygen toxicity. Caffeine is known to have a protective effect in preventing bronchopulmonary dysplasia associated with improved neurologic outcomes, although very early initiation of therapy is controversial. In this study, we used newborn rats in an oxygen injury model to test the hypothesis that near-birth caffeine administration modulates neuronal maturation and differentiation in the hippocampus of the developing brain. For this purpose, newborn Wistar rats were exposed to 21% or 80% oxygen on the day of birth for 3 or 5 days and treated with vehicle or caffeine (10 mg/kg/48 h). Postnatal exposure to 80% oxygen resulted in a drastic reduction of associated neuronal mediators for radial glia, mitotic/postmitotic neurons, and impaired cell-cycle regulation, predominantly persistent even after recovery to room air until postnatal day 15. Systemic caffeine administration significantly counteracted the effects of oxygen insult on neuronal maturation in the hippocampus. Interestingly, under normoxia, caffeine inhibited the transcription of neuronal mediators of maturing and mature neurons. The early administration of caffeine modulated hyperoxia-induced decreased neurogenesis in the hippocampus and showed neuroprotective properties in the neonatal rat oxygen toxicity model.

Chemical and biological characterization of non-extractable sulfonamide residues in soil.

For sulfonamides, the formation of non-extractable residues has been identified by laboratory testing as the most relevant concentration determining process in manured soil. Therefore, the present study has been focused on the chemical and biological characterization of non-extractable residues of (14)C-labeled sulfadiazine or sulfamethoxazole. In laboratory batch experiments, the test substances were spiked via standard solution or test slurry to microbially active soil samples. After incubation periods of up to 102d, a sequential extraction technique was applied. Despite the exhaustive extraction procedure, sulfadiazine residues mainly remained non-extractable, indicating the high affinity to the soil matrix. The remobilization of non-extractable (14)C-sulfadiazine residues was monitored in the activated sludge test and the Brassica rapa test. Only small amounts (<3%) were transferred into the extractable fractions and 0.1% was taken up by the plants. In the Lumbricus terrestris test A, the release of non-extractable (14)C-sulfamethoxazole residues by the burrowing activity of the earthworms was investigated. The residues mainly remained non-extractable (96%). The L. terrestris test B was designed to study the immobilization of (14)C-sulfamethoxazole in soil directly after the test slurry application. The mean uptake by earthworms was 1%. Extractable and non-extractable residues amounted to 5% and 93%, respectively. Consequently, the results of all tests confirmed the high affinity of the non-extractable sulfonamide residues to the soil matrix.

Regulation of inflammatory pathways by an a-tocopherol long-chain metabolite and a d-tocotrienol-related natural compound.

Vitamin E is the most important lipid antioxidant which is widely used to prevent age-associated diseases. In the liver a-tocopherol (a-TOH), the most active isomer, is metabolized by side-chain truncation. Hydroxylation and oxidation steps in peroxisomes form the long-chain metabolite (LCM) a-13'-COOH, which has been recently reported by our group to occur in human serum. Only little is known about the modes of action of the LCM. We therefore investigate the influence of the physiologically relevant a-13'-COOH and the tocotrienol (T3)-related garcinoic acid (GA) on LPS-induced inflammatory response of murine macrophages (mMF). We report here that a-13'-COOH occurs in human serum and can be detected by LC/MS-QTOF which provides evidence for its systemic bioavailability. Translating these results into mechanistic studies we use semi-synthetically derived LCM starting with garcinoic acid, isolated from the bitternut Garcinia kola, because LCMs are not commercially available as pure compounds. We also report that a-13'-COOH and GA inhibit pro-inflammatory pathways in comparison to a-TOH in LPS-stimulated mMF. A screening of inflammation-related genes showed significant decreases of Il1ß by all compounds, while Il6 and Tnfa were only down-regulated by GA. However Cox2 and iNos were significantly reduced on mRNA and protein level by more than 70% and also the formation of signaling molecules, such as NO and PGE2, was significantly reduced by a-13'-COOH and GA. Key role in regulation of inflammatory response is regulated by activation of NF?B along with p65 subunit translocation. Neither expression nor translocation were regulated by a-13'-COOH and GA. The LCM and d-T3 show high activity in inhibiting pro-inflammatory pathways and associated signal transduction. We speculate that physiological a-LCM represent a new class of regulatory metabolites.