N-Methyl-d-aspartate Receptor Stimulation Activates Tyrosinase and Promotes Melanin Synthesis in the Ink Gland of the Cuttlefish Sepia officinalis through the Nitric Oxide/cGMP Signal Transduction Pathway: A NOVEL POSSIBLE ROLE FOR GLUTAMATE AS PHYSIOLOGIC ACTIVATOR OF MELANOGENESIS *

Abstract The tyrosinase-catalyzed conversion of l-tyrosine to melanin represents the most distinctive biochemical pathway in the ink gland of the cuttlefishSepia officinalis; however, the molecular mechanisms underlying its activation have remained so far largely uncharted. In this paper we demonstrate for the first time thatl-glutamate can stimulate tyrosinase activity and promote melanin synthesis in Sepia ink gland via theN-methyl-d-aspartate (NMDA) receptor/NO/cGMP signal transduction pathway. Incubation of intact ink glands with either l-glutamate or NMDA resulted in an up to 18-fold increase of tyrosinase activity and a more than 6-fold elevation of cGMP levels. Comparable stimulation of tyrosinase was induced by an NO donor and by 8-bromo-cGMP. An NMDA receptor antagonist, NO synthase (NOS) inhibitors, and a guanylate cyclase blocker suppressed NMDA-induced effects. Immunohistochemical evidence indicated that enhanced cGMP production was localized largely in the mature part of the ink gland. Increased de novo synthesis of melanin was demonstrated in NMDA- and NO-stimulated ink glands by a combined microanalytical approach based on spectrophotometric determination of pigment levels and high performance liquid chromatography quantitation of pyrrole-2,3,5-tricarboxylic acid, a specific melanin marker, in melanosome-containing fractions. These results fill a longstanding gap in the understanding of the complex biochemical mechanisms underlying activation of melanogenesis in the mature ink gland cells of S. officinalis and disclose a novel physiologic role of the excitatory neurotransmitter glutamate mediated by the NMDA receptor/NO/cGMP signaling pathway

Migrant Labour in the Agri-Food System in Europe: Unpacking the Social and Legal Factors of Exploitation

The aim of this Special Issue is to critically explore the complex links between labour migration and the agri-food sector in Europe, drawing attention to the variety of legal and social vectors and issues at stake in the contemporary forms of exploitation underpinning the agri-food system. Our intention is to contribute to scholarly discussion on the protection of the rights of migrant workers in the agri-food system by providing an in-depth analysis of the interplay of legal, social, economic and cultural factors that foster the recourse to a low-wage and exploitable labour force in the agri-food sector, and that produce the conditions of vulnerability experienced by migrant workers in Europe. We therefore seek to provide a critical overview of the diverse drivers and processes contributing to a system that fosters workers’ dependency on employers, confines a migrant labour force to specific sectors, and, simultaneously, facilitates their continuous replacement, profiting from specific situations of social, legal and economic vulnerability

Toxic Tau Oligomers Modulated by Novel Curcumin Derivatives

The pathological aggregation and accumulation of tau, a microtubule-associated protein, is a common feature amongst more than 18 different neurodegenerative diseases that are collectively known as tauopathies. Recently, it has been demonstrated that the soluble and hydrophobic tau oligomers are highly toxic in vitro due to their capacity towards seeding tau misfolding, thereby propagating the tau pathology seen across different neurodegenerative diseases. Modulating the aggregation state of tau oligomers through the use of small molecules could be a useful therapeutic strategy to target their toxicity, regardless of other factors involved in their formation. In this study, we screened and tested a small library of newly synthesized curcumin derivatives against preformed recombinant tau oligomers. Our results show that the curcumin derivatives affect and modulate the tau oligomer aggregation pathways, converting to a more aggregated non-toxic state as assessed in the human neuroblastoma SH-SY5Y cell line and primary cortical neuron cultures. These results provide insight into tau aggregation and may become a basis for the discovery of new therapeutic agents, as well as advance the diagnostic field for the detection of toxic tau oligomers

Teaching Gender Differences at Medical School Could Improve the Safety and Efficacy of Personalized Physical Activity Prescription

..

Nitric Oxide Mediates the Stress Response Induced by Diatom Aldehydes in the Sea Urchin Paracentrotus lividus

Diatoms are ubiquitous and abundant primary producers that have been traditionally considered as a beneficial food source for grazers and for the transfer of carbon through marine food webs. However, many diatom species produce polyunsaturated aldehydes that disrupt development in the offspring of grazers that feed on these unicellular algae. Here we provide evidence that production of the physiological messenger nitric oxide increases after treatment with the polyunsaturated aldehyde decadienal in embryos of the sea urchin Paracentrotus lividus. At high decadienal concentrations, nitric oxide mediates initial apoptotic events leading to loss of mitochondrial functionality through the generation of peroxynitrite. At low decadienal concentrations, nitric oxide contributes to the activation of hsp70 gene expression thereby protecting embryos against the toxic effects of this aldehyde. When nitric oxide levels were lowered by inhibiting nitric oxide synthase activity, the expression of hsp70 in swimming blastula decreased and the proportion of abnormal plutei increased. However, in later pluteus stages nitric oxide was no longer able to exert this protective function: hsp70 and nitric oxide synthase expression decreased with a consequent increase in the expression of caspase-8. Our findings that nitric oxide production increases rapidly in response to a toxic exogenous stimulus opens new perspectives on the possible role of this gas as an important messenger to environmental stress in sea urchins and for understanding the cellular mechanisms underlying toxicity during diatom blooms

“NOI ITALIANI SIAMO COSÌ”: REALIZZARE L’IDENTITÀ IN UNA CONVERSAZIONE DI EMIGRATI ITALIANI

Una delle questioni principali nel campo della linguistica migrazionale è senza dubbio la costruzione dell’identità intesa come la costruzione linguistica dell’appartenenza ad uno o più gruppi sociali o categorie, costruita attraverso determinate pratiche linguistiche. La nozione d’identità è considerata un costrutto flessibile: la stessa persona può mettere in scena identità multiple in dipendenza dai diversi contesti d’interazione. La presente ricerca si concentra sul modo in cui le identità sono costruite e in particolare sulle strategie usate dai parlanti per rappresentare le proprie identità. I dati sono tratti dalle conversazioni di sette emigranti calabresi e mostrano come gli informanti indessicalizzano la loro identità come appartenente alla propria cultura o alla cultura del paese d’arrivo.   “Noi italiani siamo così”: realising identity in Italian migrants’ conversations  One of the main issues in the field of migration linguistics is the construction of identity within discursive practices where speakers call their identities into question starting from the language.  Indeed, identity is intended as the linguistic construction of the membership to one or more social groups or categories that are constructed through the use of communicative practices. We assume the notion of identity as a flexible construct: the same person can enact multiple identities depending on the different contexts of interaction. Our study focuses on the way identities are built and used in an encounter and, in particular, on the following research questions: Which strategies do speakers use to represent their identity? Which kind of identity do they perform? Data are taken from the conversations of seven Calabrian emigrants. Our data show that informants alternatively classify themselves as part of their own culture or the culture of the host country, through the stories they tell, showing a plurality of emerging and conflictual identities

Is Italian Agriculture "Pull Factor" for Irregular Migration -- And, If So, Why?

In discussions on irregular migration in Europe, undeclared work is generally viewed as a "pull factor"—positive aspects of a destination-country that attract an individual or group to leave their home—for both employers as well as prospective migrants, and especially in sectors such as agriculture. A closer examination of the agricultural model, however, reveals that structural forces are driving demand for work and incentivizing exploitation. This is particularly evident in Southern Italy, a region famous for its produce, where both civil society organizations and the media have documented exploitation of migrant workers. A closer examination of EU and member states efforts to avoid exploitation is needed.In Is Italian Agriculture a 'Pull Factor' for Irregular Migration—and, If So, Why?, a new study, authors from the Open Society Foundations' European Policy Institute and the European University Institute look at how Europe's Common Agricultural Policy, the practices of supermarket chains, organized crime, and gang-master recruitment practices contribute to migrant exploitation. The study further recommends a closer examination of EU member state efforts to counter exploitation and offers an overview of private sector practice's intended to combat exploitation—such as the provision of information on workers' rights, adequate housing and transport, and EU-wide labeling schemes, among others