In the present work, we investigated the response to Cd in Leptodictyum riparium, a cosmopolitan moss (Bryophyta) that can accumulate higher amounts of metals than other plants, even angiosperms, with absence or slight apparent damage. High-performance liquid chromatography followed by electrospray ionization tandem mass spectrometry of extracts from L. riparium gametophytes, exposed to 0, 36 and 360 µM Cd for 7 days, revealed the presence of γ-glutamylcysteine (γ-EC), reduced glutathione (GSH), and traces of phytochelatins. The increase in Cd concentrations progressively augmented reactive oxygen species levels, with activation of both antioxidant (catalase and superoxide dismutase) and detoxifying (glutathione-S-transferase) enzymes. After Cd treatment, cytosolic and vacuolar localization of thiol peptides was performed by means of the fluorescent dye monochlorobimane and subsequent observation with confocal laser scanning microscopy. The cytosolic fluorescence observed with the highest Cd concentrations was also consistent with the formation of γ-EC-bimane in the cytosol, possibly catalyzed by the peptidase activity of the L. riparium phytochelatin synthase. On the whole, activation of phytochelatin synthase and glutathione-S-transferase, but minimally phytochelatin synthesis, play a role to counteract Cd toxicity in L. riparium, in this manner minimizing the cellular damage caused by the metal. This study strengthens previous investigations on the L. riparium ability to efficiently hinder metal pollution, hinting at a potential use for biomonitoring and phytoremediation purposes.

Background. A novel branch of thyroid hormone (TH) signaling is represented by 3iodothyronamine (T 1 AM), an endogenous TH derivative that interacts with specific molecular targets, including trace amine associated receptor-1 (TAAR 1 ), and induces pro-learning and antiamnestic effects in mice. Dysregulation of TH signaling has long been hypothesized to play a role in Alzheimer's disease (AD). In the present investigation, we explored the neuroprotective role of T 1 AM in beta amyloid (Aβ)-induced synaptic and behavioral impairment, focusing our study on the entorhinal cortex (EC), an area which is early affected by AD pathology.Methods. Field potentials were evoked in EC layer II and long-term potentiation (LTP) was elicited by high frequency stimulation (HFS). T 1 AM (5 µM) and/or Aβ 142 (200 nM), were administered for 10 minutes, starting 5 minutes before HFS. Selective TAAR 1 agonist RO5166017 (250 nM) and TAAR 1 antagonist EPPTB (5 nM) were also used. The electrophysiological experiments were repeated in EC-slices taken from a mouse model of AD (mhAPP, J20 line). We also assessed the in vivo effects of T 1 AM on EC-dependent associative memory deficits, that were detected in mhAPP mice by behavioral evaluations based on the novel-object recognition paradigm. TAAR 1 expression was determined by Western blot, while T 1 AM and its metabolite 3-iodothyroacetic acid (TA 1

3,5-diiodo-L-thyronine (3,5-T2) is an endogenous derivative of thyroid hormone with potential metabolic effects. It has been detected in human blood by immunological methods, but a reliable assay based on mass spectrometry (MS), which is now regarded as the gold standard in clinical chemistry, is not available yet. Therefore, we aimed at developing a novel ad-hoc optimized method to quantitate 3,5-T2 and its isomers by MS in human serum. Serum samples were obtained from 28 healthy subjects. Two ml of serum were deproteinized with acetonitrile and then subjected to an optimized solid phase extraction-based procedure. To lower background noise, the samples were furtherly cleaned by hexane washing and acetonitrile precipitation of residual proteins. 3,5-T2 and its isomers 3,3′-T2 and 3′,5′-T2 were then analyzed by HPLC coupled to tandem MS. Accuracy and precision for T2 assay were 88–104% and 95–97%, respectively. Recovery and matrix effect averaged 78% and +8%, respectively. 3,5-T2 was detected in all samples and its concentration averaged (mean ± SEM) 41 ± 5 pg/ml, i.e., 78 ± 9 pmol/l. In the same samples the concentration of 3,3′-T2 averaged 133±15 pg/ml, i.e., 253±29 pmol/l, while 3′,5′-T2 was not detected. 3,5-T2 concentration was significantly related to 3,3′-T2 concentration ( r = 0.540, P < 0.01), while no significant correlation was observed with either T3 or T4 in a subset of patients in which these hormones were assayed. In conclusion, our method is able to quantify 3,5-T2 and 3,3′-T2 in human serum. Their concentrations lie in the subnanomolar range, and a significant correlation was detected between these two metabolites in healthy individuals.

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This paper reports functional studies on the enzyme phytochelatin synthase in the liverwort Marchantia polymorpha and the cyanobacterium Geitlerinema sp. strain PCC 7407. In vitro activity assays in control samples (cadmium-untreated) showed that phytochelatin synthase was constitutively expressed in both organisms. In the presence of 100 µM cadmium, in both the liverwort and the cyanobacterium, the enzyme was promptly activated in vitro, and produced phytochelatins up to the oligomer PC4. Likewise, in vivo exposure to 10–36 µM cadmium for 6-120 h induced in both organisms phytochelatin synthesis up to PC4. Furthermore, the glutathione (GSH) levels in M. polymorpha were constitutively low (compared with the average content in higher plants), but increased considerably under cadmium stress. Conversely, the GSH levels in Geitlerinema sp. PCC 7407 were constitutively high, but were halved under metal treatments. At odds with former papers, our results demonstrate that, as in M. polymorpha and other plants, the cyanobacterial phytochelatin synthase exposed to cadmium possesses manifest transpeptidasic activity, being able to synthesize phytochelatins with a degree of oligomerization higher than PC2. Therefore, prokaryotic and eukaryotic phytochelatin synthases differ less in functional terms than previously thought.

The importance of thyroid hormones in the regulation of development, growth, and energy metabolism is well known. Over the last decades, mass spectrometry has been extensively used to investigate thyroid hormone metabolism and to discover and characterize new molecules involved in thyroid hormones production, such as thyrotropin-releasing hormone. In the earlier period, the quantification methods, usually based on gas chromatography-mass spectrometry, were complicated and time consuming. They were mainly focused on basic research, and were not suitable for clinical diagnostics on a routine basis. The development of the modern mass spectrometers, mainly coupled to liquid chromatography, enabled simpler sample preparation procedures, and the accurate quantification of thyroid hormones, of their precursors, and of their metabolites in biological fluids, tissues, and cells became feasible. Nowadays, molecules of physiological and pathological interest can be assayed also for diagnostic purposes on a routine basis, and mass spectrometry is slowly entering the clinical laboratory. This review takes stock of the advancements in the field of thyroid metabolism that were carried out with mass spectrometry, with special focus on the use of this technique for the quantification of molecules involved in thyroid diseases. | INTRODUCTIONThyroid hormones (TH), namely triiodothyronine (3,5, 3′-triiodothyronine, T 3 ) and thyroxine (3,5,3′,5′-tetraiodothyronine, T 4 ), regulate development, energy metabolism, and growth, and their blood levels are controlled by complex central and peripheral signals mainly mediated by hypothalamic thyrotropin-releasing hormone (TRH) and pituitary thyrotropin (thyroid-stimulating hormone, TSH). The hypothalamic-pituitary-thyroid axis determines the set

Recent reports highlighted the significant neuroprotective effects of thyronamines (TAMs), a class of endogenous thyroid hormone derivatives. In particular, 3-iodothyronamine (T1AM) has been shown to play a pleiotropic role in neurodegeneration by modulating energy metabolism and neurological functions in mice. However, the pharmacological response to T1AM might be influenced by tissue metabolism, which is known to convert T1AM into its catabolite 3-iodothyroacetic acid (TA1). Currently, several research groups are investigating the pharmacological effects of T1AM systemic administration in the search of novel therapeutic approaches for the treatment of interlinked pathologies, such as metabolic and neurodegenerative diseases (NDDs). A critical aspect in the development of new drugs for NDDs is to know their distribution in the brain, which is fundamentally related to their ability to cross the blood–brain barrier (BBB). To this end, in the present study we used the immortalized mouse brain endothelial cell line bEnd.3 to develop an in vitro model of BBB and evaluate T1AM and TA1 permeability. Both drugs, administered at 1 µM dose, were assayed by high-performance liquid chromatography coupled to mass spectrometry. Our results indicate that T1AM is able to efficiently cross the BBB, whereas TA1 is almost completely devoid of this property.

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