Production of prostaglandins and leukotrienes by Paracoccidioides brasiliensis

Paracoccidioides brasiliensis is the causative agent of paracoccidioidomycosis, the most prevalent deep mycosis in Latin America. Production of eicosanoids, including prostaglandins and leukotrienes, during fungal infections is theorized to play a critical role on fungal survival and/or growth as well as on host immune response modulation. Host cells are one source of these mediators; however another potential source may be the fungus itself. The purpose of our study was to assess whether P. brasiliensis strains with different degree of virulence (Pb18, Pb265, PbBT79, Pb192) produce both, prostaglandin E(2) (PGE(2)) and leukotriene B(4) (LTB(4)). Moreover, we asked if P. brasiliensis can use exogenous sources of arachidonic acid (AA), as well as metabolic pathways dependent on cyclooxygenase (COX) and lipoxygenase (5-LO) enzymes, for PGE(2) and LTB(4) production, respectively. Finally, a possible association between these eicosanoids and fungus viability was assessed. We demonstrated, using ELISA assays, that all P. brasiliensis strains, independently of their virulence, produce high PGE(2) and LTB(4) levels after a 4-hour culture, which were reduced after 8 hours. However, in both culture times, higher eicosanoids levels were detected when culture medium was supplemented with exogenous AA. Differently, treatment with indomethacin, a COX inhibitor, or MK886, a 5-LO inhibitor, induces a reduction on PGE(2) and LTB(4) levels, respectively, as well as in fungus viability. The data provide evidence that P. brasiliensis is able to metabolize either endogenous or exogenous AA by pathways that depend on COX and 5-LO enzymes for producing, respectively, PGE(2) and LTB(4) that are critical for its viability

\u201cDNA Barcoding come strumento a supporto della tassonomia zoologica per pesci ossei e crostacei del Canale di Sicilia e dell\u2019identificazione univoca di specie eduli marine di interesse commerciale\u201d

La metodica molecolare del DNA Barcoding consente l'identificazione a livello di specie su scala globale utilizzando un approccio basato sul DNA standardizzato e autenticato. Le biblioteche di riferimento che contengono i Barcode validati (COI) costituiscono robusti set di dati per la verifica delle sequenze di query, fornendo notevole utilit\ue0 per identificare i pesci marini, crostacei e altri organismi. In questo studio \ue8 stata analizzata la possibilit\ue0 di utilizzare il DNA Barcode per assegnare ai campioni analizzati le specie di provenienza, pesci e crostacei, raccolti nel mar Mediterraneo centrale ed \ue8 stata sequenziata per la prima volta la regione COI nelle specie di crostacei Alphaeus glaber e Pisa nodipes e nelle specie di pesci ossei Benthocometes robustus e Parophidion vassali. E\u2019 importante sottolineare che le altre specie di crostacei, appartenenti all\u2019ordine Decapoda, Euphausiacea, Calanoida e Stomatopoda analizzate nello studio, fin ora erano presenti nel database GenBank\uae solo per individui di provenienza atlantica e del Mare del Nord. Come per i crostacei analizzati in questo studio, anche per gli individui di pesci ossei, \ue8 stato importantissimo risalire alle sequenze nucleotidiche relative alla regione COI per alcune specie mediterranee, in quanto per la maggioranza delle specie trattate, queste non erano presenti. La procedura di estrazione del DNA totale (come lisato grezzo), testata in questo studio \ue8 rapida, economica, semplice e affidabile ed \ue8 molto efficace nelle analisi dei campioni, indipendentemente dalle condizioni di conservazione (congelamento, affumicatura, fissazione 6 fisica o chimica), dal tipo di tessuto. Inoltre coniugando la procedura di estrazione del DNA totale (come lisato grezzo) con lo strumento DNA Barcode e l\u2019utilizzo di primer specie-specifici, \ue8 stato realizzato un kit per l\u2019identificazione rapida di 10 specie di pregio commerciale selezionate (Xiphias gladius, Sardina pilchardus, Scombers scombrus, Sparus aurata, Dicentrarchus labrax, Sepia officinalis, Loligo vulgaris, Todarodes sagittatus, Palinurus elephas e Aristaeomorpha foliacea). Tale kit rappresenta un punto di partenza cruciale nella certificazione del prodotto ittico su scala economico-commerciale

Moment tensor inversion of perforation shots using distributed acoustic sensing

Distributed acoustic sensing (DAS) fibers have enabled various geophysical applications in unconventional reservoirs. Combined with perforation shots, a DAS fiber can record valuable guided waves that propagate in the reservoir formation and carry information about its properties. However, the representation of perforation shots as seismic sources, needed to conduct quantitative analysis, remains unknown. We model such sources using a superposition of three mechanisms for which we derive the moment tensor representation. Using field DAS data recorded in the same well where the perforations are located, we establish a workflow to invert the resolvable components of the total moment tensor for 100 different perforation shots. By scrutinizing the inversion results, we conjecture that the moment tensor can indicate how effectively a perforation shot creates micro-cracks in the surrounding rock. Furthermore, our inverted moment tensors form the basis for a subsequent elastic full-waveform inversion.Comment: This work has been submitted for publication in Geophysics under the reference GEO-2023-004

Carbon fluxes in coral reefs. II. Eulerian study of inorganic carbon dynamics and measurement of air-sea CO₂ exchanges

Air-sea CO2 exchanges and the partial pressure of CO2 were measured in surface water overlying 2 coral reefs: Moorea (French Polynesia, austral winter, August 1992), where coral diversity and surface cover are low, and Yonge Reef (Great Barrier Reef, austral summer, December 1993), where coral diversity and cover are comparatively higher. A procedure is proposed to estimate the potential CO2 exchange with the atmosphere by taking into account both the saturation level of oceanic seawater and the equilibration process occurring after water leaves the reef. It is shown that both sites were net sources of CO2 to the atmosphere as a result of the effect of calcification on the dynamics of the inorganic carbon system. The potential global CO2 evasion from the ocean to the atmosphere is about 4 times higher at Yonge Reef than at Moorea. It is also demonstrated that, at both sites, the major exchange of CO2 from sea to air occurs as seawater returns to chemical equilibrium after it has crossed and left the reef. The dynamics of inorganic carbon were studied using the so-called homogeneous buffer factor [beta = dln(pCO(2))/dln(DIC)] (where pCO(2) is the CO2 partial pressure in surface water and DIC is dissolved inorganic carbon), which gave estimates that approximately 80% of the change in inorganic carbon was related to photosynthesis and respiration. This approach showed that the calcification rate was proportional to the net organic production during the day and to the respiration rate at night

2 years-long monitoring of <i>Codium elisabethae</i> population dynamics in the Azorian reef ecosystem (Faial Island) with seabed imagery

In the Site of Community Interest (Natura, 2000) of Monte-da-Guia (Faial, Azores), two sites were delimited in order to investigate particularly the links between habitat characteristics, population structure, distribution and dynamics of the green alga Codium elisabethae. The first site is a large protected rocky seafloor of an ancient volcano crater (20m deep) and classified as no-go reserve. It shows very high density stands of Codium elisabethae (up to 105 ind.m-2), representing the main vegetal biomass. At similar depth but distant of about two kilometers, the second site is in a more exposed area, where a sparse population (about 13 ind.m-2) occupies rocky tables and boulders emerging from shallow sandy deposits. These contrasting densities reflect different population dynamic equilibrium resulting from the particular environmental pressures of each site. A two year population survey started in August 2003, aiming principally at building submarine image mosaics of each site on a seasonal basis. Further, a computer assisted detection is run on the images to derive valuable information about the studied macroalgae. This technique allows to study a comparatively large zone regarding to the diving time invested so as to integrate spatial patchiness and to focus on the temporal evolution of well identified individuals. The imagery methodology was validated with in situ measurements, confirming the adequacy of the 1cm precision size histograms produced, when considering individuals larger than 5cm diameter. Seasonal fluctuations of growth rate (from 0.5 to 3cm.month-1) and primary production (from 1 to 15kg.m-².month-1) could be described. For both sites studied, density, biomass and cover rate seemed affected by a seasonal variation with reduction starting in end summer early autumn. In both sites, the reduction was sharp in the fall 2003 and population density didn’t recover completely in spring and summer 2004. During the following year, population of the protected site could maintain density and biomass, while population of the exposed site dropped continuously all year. Last processing step will search to relate statistically these different population evolutions to the benthic environmental constraints measured in both sites during the year 2004-2005 (temperature, currents, turbidity, photosynthetic active radiation, nutrients). Differences in hydrodynamic exposure of both sites could be part of the answer, but observed differences in the reproduction intensity of these two populations is an important factor, and remains unexplained