Characterization of the molecular mechanisms of silicon uptake in coccolithophores.

Coccolithophores are an important group of calcifying marine phytoplankton. Although coccolithophores are not silicified, some species exhibit a requirement for Si in the calcification process. These species also possess a novel protein (SITL) that resembles the SIT family of Si transporters found in diatoms. However, the nature of Si transport in coccolithophores is not yet known, making it difficult to determine the wider role of Si in coccolithophore biology. Here, we show that coccolithophore SITLs act as Na+ -coupled Si transporters when expressed in heterologous systems and exhibit similar characteristics to diatom SITs. We find that CbSITL from Coccolithus braarudii is transcriptionally regulated by Si availability and is expressed in environmental coccolithophore populations. However, the Si requirement of C. braarudii and other coccolithophores is very low, with transport rates of exogenous Si below the level of detection in sensitive assays of Si transport. As coccoliths contain only low levels of Si, we propose that Si acts to support the calcification process, rather than forming a structural component of the coccolith itself. Si is therefore acting as a micronutrient in coccolithophores and natural populations are only likely to experience Si limitation in circumstances where dissolved silicon (DSi) is depleted to extreme levels.

Global variability in seawater Mg:Ca and Sr:Ca ratios in the modern ocean.

Seawater Mg:Ca and Sr:Ca ratios are biogeochemical parameters reflecting the Earth-ocean-atmosphere dynamic exchange of elements. The ratios' dependence on the environment and organisms' biology facilitates their application in marine sciences. Here, we present a measured single-laboratory dataset, combined with previous data, to test the assumption of limited seawater Mg:Ca and Sr:Ca variability across marine environments globally. High variability was found in open-ocean upwelling and polar regions, shelves/neritic and river-influenced areas, where seawater Mg:Ca and Sr:Ca ratios range from ∼4.40 to 6.40 mmol:mol and ∼6.95 to 9.80 mmol:mol, respectively. Open-ocean seawater Mg:Ca is semiconservative (∼4.90 to 5.30 mol:mol), while Sr:Ca is more variable and nonconservative (∼7.70 to 8.80 mmol:mol); both ratios are nonconservative in coastal seas. Further, the Ca, Mg, and Sr elemental fluxes are connected to large total alkalinity deviations from International Association for the Physical Sciences of the Oceans (IAPSO) standard values. Because there is significant modern seawater Mg:Ca and Sr:Ca ratios variability across marine environments we cannot absolutely assume that fossil archives using taxa-specific proxies reflect true global seawater chemistry but rather taxa- and process-specific ecosystem variations, reflecting regional conditions. This variability could reconcile secular seawater Mg:Ca and Sr:Ca ratio reconstructions using different taxa and techniques by assuming an error of 1 to 1.50 mol:mol, and 1 to 1.90 mmol:mol, respectively. The modern ratios' variability is similar to the reconstructed rise over 20 Ma (Neogene Period), nurturing the question of seminonconservative behavior of Ca, Mg, and Sr over modern Earth geological history with an overlooked environmental effect.

TGF-ß pro-oligodendrogenic effects on adult SVZ progenitor cultures and its interaction with the Notch signaling pathway.

Adult neural progenitor cells (NPCs) are capable of differentiating into neurons, astrocytes, and oligodendrocytes throughout life. Notch and transforming growth factor ß1 (TGF-ß) signaling pathways play critical roles in controlling these cell fate decisions. TGF-ß has been previously shown to exert pro-neurogenic effects on hippocampal and subventricular zone (SVZ) NPCs in vitro and to interact with Notch in different cellular types. Therefore, the aim of our work was to study the effect of TGF-ß on adult rat brain SVZ NPC glial commitment and its interaction with Notch signaling. Initial cell characterization revealed a large proportion of Olig2+, Nestin+, and glial fibrillary acidic protein (GFAP+) cells, a low percentage of platelet-derived growth factor receptor α (PDGFRα+) or NG2+ cells, and <1% Tuj1+ cells. Immunocytochemical analyses showed a significant increase in the percentage of PDGFRα+, NG2+, and GFAP+ cells upon four-day TGF-ß treatment, which demonstrates the pro-gliogenic effect of this growth factor on adult brain SVZ NPCs. Real-time polymerase chain reaction analyses showed that TGF-ß induced the expression of Notch ligand Jagged1 and downstream gene Hes1. Notch signaling inhibition in cultures treated with TGF-ß produced a decrease in the proportion of PDGFRα+ cells, while TGF-ß receptor II (TßRII) inhibition also rendered a decrease in the proportion of PDGFRα+ cells, concomitantly with a decrease in Jagged1 levels. These findings demonstrate the participation of Notch signaling in TGF-ß effects and illustrate the impact of TGF-ß on glial cell fate decisions of adult brain SVZ NPCs, as well as on oligodendroglial progenitor cell proliferation and maturation.

Addressing the information gap: developing and implementing a cervical cancer prevention education campaign grounded in principles of community-based participatory action.

Despite significant advances in prevention, Mexican American women continue to experience disparities related to cervical cancer and access to current and relevant health information. To address this disparity a community-campus partnership initiated an outreach program to Latinas in Arizona as one part of an integrated approach. Promotoras (community health workers) provided the leadership in the development of a curriculum to (a) train promotoras on cervical cancer, (b) meet informational needs of community members, (c) address relevant social determinants of heath, and (d) promote access to health care. The purpose of this article is to describe the community-based participatory approach used in the development of the curriculum. Specifically, the article describes the leadership of promotoras, the curriculum development, and the use of continual feedback to inform the quality control. To address cervical cancer disparities for Mexican American women, the Pima County Cervical Cancer Prevention Partnership used principles of community-based participatory action.

Can participatory processes lead to changes in the configuration of local mental health networks? A social network analysis.

Systems modeling offers a valuable tool to support strategic decision-making for complex problems because it considers the causal inter-relationships that drive population health outcomes. This tool can be used to simulate policies and initiatives to determine which combinations are likely to deliver the greatest impacts and returns on investment. Systems modeling benefits from participatory approaches where a multidisciplinary stakeholder group actively engages in mapping and contextualizing causal mechanisms driving complex system behaviors. Such approaches can have significant advantages, including that they may improve connection and coordination of the network of stakeholders operating across the system; however, these are often observed in practice as colloquial anecdotes and seldom formally assessed. We used a basic social network analysis to explore the impact on the configuration of the network of mental health providers, decision-makers, and other stakeholders in Bogota, Colombia active in a series of three workshops throughout 2021 and 2022. Overall, our analysis suggests that the participatory process of the systems dynamics exercise impacts the social network's structure, relationships, and dynamics.

Diagnostic Usefulness of Flexible Fibroscopy Biopsy in Suspected Lesions of the Otolaryngological Area.

The efficiency in the management of patients with suspected malignant lesions represents the main objective of the oncology of head and neck. Flexible nasopahyngolaryngoscopy with working channel allows to quickly and safely assess and obtain histological samples of this type of lesion. Our objective is to describe the usefulness of this technique in lesions suggestive of malignancy in terms of efficiency, sensitivity and specificity. A retrospective study was carried out over a period of time from December 2014 to December 2019, including patients biopsied with flexible fibroscopy of lesions of debut suspected of malignancy. Here we assess the location of the lesion, the histological results, the diagnostic time and the epidemiological variables. 104 patients were included in the study. More than half of the lesions, 55.2% (57), were located in the larynx; 57.7% (60) resulted positive for malignancy in the flexible fiberscope biopsy; 19.2% (20) were taken to the operating room to get biopsied under general anesthesia resulting in 7.4% (14) positive for malignancy, which shows a sensitivity of the test of 81%. In our sample, a diagnostic time of 15 days was obtained. Considering our results, the few complications and the revised literature, flexible fiberscope biopsy with working channel is an efficient procedure for the management of oncological patients of head and neck.

Demyelination-remyelination in the Central Nervous System: Ligand-dependent Participation of the Notch Signaling Pathway.

Multiple sclerosis (MS) is an immune-mediated central nervous system disease mostly affecting young people. Multiple sclerosis and other neurodegenerative and white matter disorders involve oligodendrocyte (OL) damage and demyelination. Therefore, elucidating the signaling pathways involved in the remyelination process through the maturation of OL progenitor cells (OPCs) may contribute to the development of new therapeutic approaches. In this context, this paper further characterizes toxic cuprizone (CPZ)-induced demyelination and spontaneous remyelination in rats and investigates the role of ligand-dependent Notch signaling activation along demyelination/remyelination both in vivo and in vitro. Toxic treatment generated an inflammatory response characterized by both microgliosis and astrogliosis. Interestingly, early demyelination revealed an increase in the proportion of Jagged1+/GFAP+ cells, which correlated with an increase in Jagged1 transcript and concomitant Jagged1-driven Notch signaling activation, particularly in NG2+ OPCs, in both the corpus callosum (CC) and subventricular zone (SVZ). The onset of remyelination then exhibited an increase in the proportion of F3/contactin+/NG2+ cells, which correlated with an increase in F3/contactin transcript during ongoing remyelination in the CC. Moreover, neurosphere cultures revealed that neural progenitor cells present in the brain SVZ of CPZ-treated rats recapitulate in vitro the mechanisms underlying the response to toxic injury observed in vivo, compensating for mature OL loss. Altogether, the present results offer strong evidence of cell-type and ligand-specific Notch signaling activation and its time- and area-dependent participation in toxic demyelination and spontaneous remyelination.

Phenotypic Variability in the Coccolithophore Emiliania huxleyi.

Coccolithophores are a vital part of oceanic phytoplankton assemblages that produce organic matter and calcium carbonate (CaCO3) containing traces of other elements (i.e. Sr and Mg). Their associated carbon export from the euphotic zone to the oceans' interior plays a crucial role in CO2 feedback mechanisms and biogeochemical cycles. The coccolithophore Emiliania huxleyi has been widely studied as a model organism to understand physiological, biogeochemical, and ecological processes in marine sciences. Here, we show the inter-strain variability in physiological and biogeochemical traits in 13 strains of E. huxleyi from various biogeographical provinces obtained from culture collections commonly used in the literature. Our results demonstrate that inter-strain genetic variability has greater potential to induce larger phenotypic differences than the phenotypic plasticity of single strains cultured under a broad range of variable environmental conditions. The range of variation found in physiological parameters and calcite Sr:Ca highlights the need to reconsider phenotypic variability in paleoproxy calibrations and model parameterizations to adequately translate findings from single strain laboratory experiments to the real ocean.

Understanding Bioluminescence in Dinoflagellates-How Far Have We Come?

Some dinoflagellates possess the remarkable genetic, biochemical, and cellular machinery to produce bioluminescence. Bioluminescent species appear to be ubiquitous in surface waters globally and include numerous cosmopolitan and harmful taxa. Nevertheless, bioluminescence remains an enigmatic topic in biology, particularly with regard to the organisms' lifestyle. In this paper, we review the literature on the cellular mechanisms, molecular evolution, diversity, and ecology of bioluminescence in dinoflagellates, highlighting significant discoveries of the last quarter of a century. We identify significant gaps in our knowledge and conflicting information and propose some important research questions that need to be addressed to advance this research field.