microbeMASST: a taxonomically informed mass spectrometry search tool for microbial metabolomics data

microbeMASST, a taxonomically informed mass spectrometry (MS) search tool, tackles limited microbial metabolite annotation in untargeted metabolomics experiments. Leveraging a curated database of >60,000 microbial monocultures, users can search known and unknown MS/MS spectra and link them to their respective microbial producers via MS/MS fragmentation patterns. Identification of microbe-derived metabolites and relative producers without a priori knowledge will vastly enhance the understanding of microorganisms' role in ecology and human health.

A Taxonomically-informed Mass Spectrometry Search Tool for Microbial Metabolomics Data

MicrobeMASST, a taxonomically-informed mass spectrometry (MS) search tool, tackles limited microbial metabolite annotation in untargeted metabolomics experiments. Leveraging a curated database of >60,000 microbial monocultures, users can search known and unknown MS/MS spectra and link them to their respective microbial producers via MS/MS fragmentation patterns. Identification of microbial-derived metabolites and relative producers, without a priori knowledge, will vastly enhance the understanding of microorganisms' role in ecology and human health.

Effect of gastrin-releasing peptide on rat hippocampal extracellular GABA levels and seizures in the audiogenic seizure-prone DBA/2 mouse

Gastrin-releasing peptide (GRP), a selective agonist for the BB(2) subtype of bombesin receptor, is reported to depolarise GABAergic interneurons in the stratum oriens layer of the hippocampus. Such an action might lead to increased extracellular levels of GABA in the hippocampus, and result in an anti-convulsant effect with this peptide. We have tested this hypothesis by determining the effect of GRP on extracellular levels of GABA in the ventral hippocampus of the freely moving rat using in vivo microdialysis, and by intracerebroventricular (i.c.v.) administration of GRP to audiogenic seizure-prone DBA/2 mice prior to exposure to the noise of an electric bell. Following local perfusion in the ventral hippocampus by reverse dialysis GRP (10 microM) significantly raised levels of GABA in the recovered dialysates by approximately 40%. In the seizure studies, GRP (30-300 ng) increased the latency to tonic seizure, the number of mice convulsing and reduced the incidence of lethality. In both dialysis and seizure studies, the effects of GRP were blocked by the selective BB(2) receptor antagonist, [D-Phe(6), Leu-NHEt(13)]bombesin (6-13). These experiments provide further functional evidence that activation of the BB(2) receptor may modulate neurotransmission in the hippocampus, and that this action may confer anti-convulsant properties on agonists acting at the BB(2) receptor in the brain.

Bombesin-like peptides depolarize rat hippocampal interneurones through interaction with subtype 2 bombesin receptors

1. Whole-cell patch-clamp recordings were made from visually identified hippocampal interneurones in slices of rat brain tissue in vitro. Bath application of the bombesin-like neuropeptides gastrin-releasing peptide (GRP) or neuromedin B (NMB) produced a large membrane depolarization that was blocked by pre-incubation with the subtype 2 bombesin (BB2) receptor antagonist [D-Phe6, Des-Met14]bombesin-(6-14)ethyl amide. 2. The inward current elicited by NMB or GRP was unaffected by K+ channel blockade with external Ba2+ or by replacement of potassium gluconate in the electrode solution with caesium acetate. 3. Replacement of external NaCl with Tris-HCl significantly reduced the magnitude of the GRP-induced current at -60 mV. In contrast, replacement of external NaCl with LiCl had no effect on the magnitude of this current. 4. Photorelease of caged GTPgammaS inside neurones irreversibly potentiated the GRP-induced current at -60 mV. Similarly, bath application of the phospholipase C (PLC) inhibitor U-73122 significantly reduced the size of the inward current induced by GRP. 5. Reverse transcription followed by the polymerase chain reaction using cytoplasm from single hippocampal interneurones demonstrated the expression of BB2 receptor mRNA together with glutamate decarboxylase (GAD67). 6. Although bath application of GRP or NMB had little or no effect on the resting membrane properties of CA1 pyramidal cells per se, these neuropeptides produced a dramatic increase in the number and amplitude of miniature inhibitory postsynaptic currents in these cells in a TTX-sensitive manner.

Anticonvulsant agents, dizocilpine maleate, enadoline and HA 966 have different effects on N-methyl-DL-aspartate-induced immediate early gene induction in mice

Administration of N-methyl-DL-aspartate (85 mg/ml) was given by infusion (0.14 ml/min) until a clonic seizure was elicited. In situ hybridization was used to assess regional levels of four immediate early gene messenger RNA levels (c-fos, c-jun, junB, and a nerve growth factor induced gene, NGFI-A). Messenger RNA levels were highest at 25 min following infusion of N-methyl-DL-aspartate. c-jun messenger RNA levels remained elevated for over 2 h; however, c-fos, junB and, NGFI-A messenger RNA levels had returned to control levels by this time. Expression was detected in the hippocampus, hypothalamus and piriform cortex. Pre-treatment (30 min prior to N-methyl-DL-aspartate) with the anticonvulsant drugs dizocilpine maleate (1 mg/kg) and HA 966 (200 micrograms, i.c.v.) resulted in significantly reduced immediate early gene messenger RNA levels in the hypothalamus and piriform cortex, and attenuated levels in the hippocampus. Pre-treatment with the anticonvulsant agent enadoline (3 mg/kg), given at an anticonvulsant dose, did not result in reduced immediate early gene messenger RNA levels. These results suggest that monitoring immediate early gene expression may lead to advances in the understanding of the mechanism of action of many pharmacological agents, such as the kappa-opioid agonist enadoline.