The Functions of Auxilin and Rab11 in Drosophila Suggest That the Fundamental Role of Ligand Endocytosis in Notch Signaling Cells Is Not Recycling

Notch signaling requires ligand internalization by the signal sending cells. Two endocytic proteins, epsin and auxilin, are essential for ligand internalization and signaling. Epsin promotes clathrin-coated vesicle formation, and auxilin uncoats clathrin from newly internalized vesicles. Two hypotheses have been advanced to explain the requirement for ligand endocytosis. One idea is that after ligand/receptor binding, ligand endocytosis leads to receptor activation by pulling on the receptor, which either exposes a cleavage site on the extracellular domain, or dissociates two receptor subunits. Alternatively, ligand internalization prior to receptor binding, followed by trafficking through an endosomal pathway and recycling to the plasma membrane may enable ligand activation. Activation could mean ligand modification or ligand transcytosis to a membrane environment conducive to signaling. A key piece of evidence supporting the recycling model is the requirement in signaling cells for Rab11, which encodes a GTPase critical for endosomal recycling. Here, we use Drosophila Rab11 and auxilin mutants to test the ligand recycling hypothesis. First, we find that Rab11 is dispensable for several Notch signaling events in the eye disc. Second, we find that Drosophila female germline cells, the one cell type known to signal without clathrin, also do not require auxilin to signal. Third, we find that much of the requirement for auxilin in Notch signaling was bypassed by overexpression of both clathrin heavy chain and epsin. Thus, the main role of auxilin in Notch signaling is not to produce uncoated ligand-containing vesicles, but to maintain the pool of free clathrin. Taken together, these results argue strongly that at least in some cell types, the primary function of Notch ligand endocytosis is not for ligand recycling

Distinct intracellular motifs of Delta mediate its ubiquitylation and activation by Mindbomb1 and Neuralized

Ubiquitylation of the intracellular domain of Drosophila Delta is necessary for Notch activation

Study of strandings of the jellyfish Pelagia noctiluca in the Mediterranean coastline of Tetouan (NW of the Morocco)

Trabajo presentado en el 2nd Scientific Workshop PERSEUS, celebrado en Marrakesh del 2 al 4 de diciembre de 2014.For a decade, we noticed outbreaks of jellyfish strandings in the coastline of Tetouan especially during heat waves. To examine factors that may be responsible for the stranding of the jellyfish Pelagia noctiluca (Forsskål, 1775) in the coastline of Tetouan (occidental Mediterranean part of Morocco), a monthly monitoring was done at 2 sites (M'diq and Martil) in the years 2011 and 2012. In this study the appearance of these organisms is studied in relation with the tidal currents, wind currents (East wind), weather conditions of the area and physic-chemical parameters of seawater. The appearance of this jellyfish began in June (22.1° C) and reached the maximum of abundance or density in September (24.7° C) to disappear in October. This density fluctuation is correlated with changes in ambient temperature. Analysis of the structure of the population size (umbrella diameter) of the jellyfish shows a size range between 10 mm and 90 mm and an average of 49 mm. Other studies have also observed that the outbreak of the Medusa seems to be related to warm temperatures. Nevertheless, the different processes that are involved in the appearance of jellyfish in a specific coastal area operate at diverse time and spatial scales, which demand to take into account an wide perspective in order to analyze their population dynamics.N

A case study of aerosol trace element deposition to Moroccan coastal waters

European Aerosol Conference (EAC 2016), Tours, FRA, 04-/09/2016 - 09/09/201

International conference ICAWA 2016 : extended book of abstract : the AWA project : ecosystem approach to the management of fisheries and the marine environment in West African waters

Aerosol deposition is an important source of trace elements (TEs) to the surface ocean. Due to the proximity to the Sahara and Sahel Deserts, the North Atlantic receives some of the highest inputs of mineral dust globally (~100- 220 Tg yr-1). In terms of biological production, this significant input of TEs contributes to the greater efficiency of the Canary Current Eastern Boundary Upwelling System (CC-EBUS) relative to its Pacific counterpart; both of which support socio-economically important fisheries. However, mineral dust is just one component of atmospheric aerosols. Human activities (e.g. fossil fuel combustion, agricultural practices) also contribute to the atmospheric load, resulting in changes in the elemental ratios with respect to crustal composition. In order to investigate the TE composition of aerosols to the CC-EBUS, aerosol samples were collected from three coastal locations in Morocco (Agadir, Laayoune and Dakhla) as part of the EPURE project, over an annual cycle (March 2015-2016). Here, we present TE composition data, with a focus on cadmium (Cd); an element of concern for human health, which is toxic to phytoplankton above a certain threshold, despite being essential for carbon uptake in some genera. A poor correlation between aerosol aluminium (Al; a tracer for mineral dust inputs) and Cd (r2 = 0.31, P = 0.091) suggests that mineral dust was not the dominant source of Cd during this study. However, coincident peaks of Al and Cd did occur occasionally, suggesting that during dust events mineral dust could be an important source of Cd. In addition, despite the presence of phosphate mining activities south of Laayoune, we did not observe significantly different ratios of Cd/Al relative to the other two stations. Using aerosol samples collected during the AWA campaigns off Senegal (2013, 2014) we have estimated the solubility of TEs from West African/European aerosols to provide an estimate of the flux of potentially bioavailable TEs for marine micro-organisms

A case study of aerosol trace element deposition to Moroccan coastal waters : lessons from the AWA Project [résumé]

ICAWA : International Conference AWA, Dakar, SEN, 13-/12/2016 - 15/12/2016Aerosol deposition is an important source of trace elements (TEs) to the surface ocean. Due to the proximity to the Sahara and Sahel Deserts, the North Atlantic receives some of the highest inputs of mineral dust globally (~100- 220 Tg yr-1). In terms of biological production, this significant input of TEs contributes to the greater efficiency of the Canary Current Eastern Boundary Upwelling System (CC-EBUS) relative to its Pacific counterpart; both of which support socio-economically important fisheries. However, mineral dust is just one component of atmospheric aerosols. Human activities (e.g. fossil fuel combustion, agricultural practices) also contribute to the atmospheric load, resulting in changes in the elemental ratios with respect to crustal composition. In order to investigate the TE composition of aerosols to the CC-EBUS, aerosol samples were collected from three coastal locations in Morocco (Agadir, Laayoune and Dakhla) as part of the EPURE project, over an annual cycle (March 2015-2016). Here, we present TE composition data, with a focus on cadmium (Cd); an element of concern for human health, which is toxic to phytoplankton above a certain threshold, despite being essential for carbon uptake in some genera. A poor correlation between aerosol aluminium (Al; a tracer for mineral dust inputs) and Cd (r2 = 0.31, P = 0.091) suggests that mineral dust was not the dominant source of Cd during this study. However, coincident peaks of Al and Cd did occur occasionally, suggesting that during dust events mineral dust could be an important source of Cd. In addition, despite the presence of phosphate mining activities south of Laayoune, we did not observe significantly different ratios of Cd/Al relative to the other two stations. Using aerosol samples collected during the AWA campaigns off Senegal (2013, 2014) we have estimated the solubility of TEs from West African/European aerosols to provide an estimate of the flux of potentially bioavailable TEs for marine micro-organisms

A case study of aerosol trace element deposition to Moroccan coastal waters : lessons from the AWA Project [résumé]

ICAWA : International Conference AWA, Dakar, SEN, 13-/12/2016 - 15/12/2016Aerosol deposition is an important source of trace elements (TEs) to the surface ocean. Due to the proximity to the Sahara and Sahel Deserts, the North Atlantic receives some of the highest inputs of mineral dust globally (~100- 220 Tg yr-1). In terms of biological production, this significant input of TEs contributes to the greater efficiency of the Canary Current Eastern Boundary Upwelling System (CC-EBUS) relative to its Pacific counterpart; both of which support socio-economically important fisheries. However, mineral dust is just one component of atmospheric aerosols. Human activities (e.g. fossil fuel combustion, agricultural practices) also contribute to the atmospheric load, resulting in changes in the elemental ratios with respect to crustal composition. In order to investigate the TE composition of aerosols to the CC-EBUS, aerosol samples were collected from three coastal locations in Morocco (Agadir, Laayoune and Dakhla) as part of the EPURE project, over an annual cycle (March 2015-2016). Here, we present TE composition data, with a focus on cadmium (Cd); an element of concern for human health, which is toxic to phytoplankton above a certain threshold, despite being essential for carbon uptake in some genera. A poor correlation between aerosol aluminium (Al; a tracer for mineral dust inputs) and Cd (r2 = 0.31, P = 0.091) suggests that mineral dust was not the dominant source of Cd during this study. However, coincident peaks of Al and Cd did occur occasionally, suggesting that during dust events mineral dust could be an important source of Cd. In addition, despite the presence of phosphate mining activities south of Laayoune, we did not observe significantly different ratios of Cd/Al relative to the other two stations. Using aerosol samples collected during the AWA campaigns off Senegal (2013, 2014) we have estimated the solubility of TEs from West African/European aerosols to provide an estimate of the flux of potentially bioavailable TEs for marine micro-organisms