Impact environnemental et évaluation de la qualité des eaux par des méthodes chimiques et biologiques « Diatomées »

Le but de cette étude est de surveiller la qualité des eaux de la Merja Fouarat par l’utilisation des diatomées benthiques comme bio-indicateurs et des variables chimiques telles que DBO5, ammoniums, nitrites et phosphates. L’évolution spatio-temporelle des valeurs de l’Indice de pollution organique (IPO) et de l’indice diatomique Leclercq (IDL), montrent que l’eau de la Merja Fouarat est fortement polluée à cause des rejets non traités des eaux usées domestiques et industrielles. L’IDL et L’IPO se classent dans le même niveau de pollution avec un écart faible (0,27-0,3-0,5-0,2-0,3), témoin que les diatomées intègrent les variations des facteurs polluants. Par ailleurs, les espèces rencontrées possèdent un caractère alcaliphyle prononcé avec uneabondance des espèces résistantes à la pollution organique.Mots clés : Diatomées, qualité de l’eau, bio-indicateur, IDL, IPO, Merja Fouarat

Nicotine up-regulates α4β2 nicotinic receptors and ER exit sites via stoichiometry-dependent chaperoning

The up-regulation of α4β2* nicotinic acetylcholine receptors (nAChRs) by chronic nicotine is a cell-delimited process and may be necessary and sufficient for the initial events of nicotine dependence. Clinical literature documents an inverse relationship between a person’s history of tobacco use and his or her susceptibility to Parkinson’s disease; this may also result from up-regulation. This study visualizes and quantifies the subcellular mechanisms involved in nicotine-induced nAChR up-regulation by using transfected fluorescent protein (FP)-tagged α4 nAChR subunits and an FP-tagged Sec24D endoplasmic reticulum (ER) exit site marker. Total internal reflection fluorescence microscopy shows that nicotine (0.1 µM for 48 h) up-regulates α4β2 nAChRs at the plasma membrane (PM), despite increasing the fraction of α4β2 nAChRs that remain in near-PM ER. Pixel-resolved normalized Förster resonance energy transfer microscopy between α4-FP subunits shows that nicotine stabilizes the (α4)2(β2)3 stoichiometry before the nAChRs reach the trans-Golgi apparatus. Nicotine also induces the formation of additional ER exit sites (ERES). To aid in the mechanistic analysis of these phenomena, we generated a β2enhanced-ER-export mutant subunit that mimics two regions of the β4 subunit sequence: the presence of an ER export motif and the absence of an ER retention/retrieval motif. The α4β2enhanced-ER-export nAChR resembles nicotine-exposed nAChRs with regard to stoichiometry, intracellular mobility, ERES enhancement, and PM localization. Nicotine produces only small additional PM up-regulation of α4β2enhanced-ER-export receptors. The experimental data are simulated with a model incorporating two mechanisms: (1) nicotine acts as a stabilizing pharmacological chaperone for nascent α4β2 nAChRs in the ER, eventually increasing PM receptors despite a bottleneck(s) in ER export; and (2) removal of the bottleneck (e.g., by expression of the β2enhanced-ER-export subunit) is sufficient to increase PM nAChR numbers, even without nicotine. The data also suggest that pharmacological chaperoning of nAChRs by nicotine can alter the physiology of ER processes

Y Chromosome Lineages in Men of West African Descent

The early African experience in the Americas is marked by the transatlantic slave trade from ∼1619 to 1850 and the rise of the plantation system. The origins of enslaved Africans were largely dependent on European preferences as well as the availability of potential laborers within Africa. Rice production was a key industry of many colonial South Carolina low country plantations. Accordingly, rice plantations owners within South Carolina often requested enslaved Africans from the so-called “Grain Coast” of western Africa (Senegal to Sierra Leone). Studies on the African origins of the enslaved within other regions of the Americas have been limited. To address the issue of origins of people of African descent within the Americas and understand more about the genetic heterogeneity present within Africa and the African Diaspora, we typed Y chromosome specific markers in 1,319 men consisting of 508 west and central Africans (from 12 populations), 188 Caribbeans (from 2 islands), 532 African Americans (AAs from Washington, DC and Columbia, SC), and 91 European Americans. Principal component and admixture analyses provide support for significant Grain Coast ancestry among African American men in South Carolina. AA men from DC and the Caribbean showed a closer affinity to populations from the Bight of Biafra. Furthermore, 30–40% of the paternal lineages in African descent populations in the Americas are of European ancestry. Diverse west African ancestries and sex-biased gene flow from EAs has contributed greatly to the genetic heterogeneity of African populations throughout the Americas and has significant implications for gene mapping efforts in these populations

Age-dependent effects of protein restriction on dopamine release

FUNDING AND DISCLOSURE This work was supported by the Biotechnology and Biological Sciences Research Council [grant # BB/M007391/1 to J.E.M.], the European Commission [grant # GA 631404 to J.E.M.], The Leverhulme Trust [grant # RPG-2017-417 to J.E.M.] and the Tromsø Research Foundation [grant # 19-SG-JMcC to J. E. M.). The authors declare no conflict of interest. ACKNOWLEDGEMENTS The authors would like to acknowledge the help and support from the staff of the Division of Biomedical Services, Preclinical Research Facility, University of Leicester, for technical support and the care of experimental animals.Peer reviewedPublisher PD

Étude de quelques champignons coprinoïdes de la forêt domaniale du site minier Jerada (Nord-Est du Maroc) dont Coprinellus bipellis et Coprinopsis strossmayeri sont nouvelles pour la flore fongique du Maroc

Objectif : Le travail présenté ici a pour objectif d’étudier la flore fongique de la forêt domaniale de Beni Yaala du site minier de Jerada (Nord-est du Maroc).Méthodologie et résultats : Des prospections effectuées dans la région de l’étude ont permis de noter des renseignements sur les espèces fongiques rencontrées. Au laboratoire, les critères macroscopiques et microscopiques d’identification de ces espèces ont été déterminés. Six espèces de Basidiomycètes Macromycètes ont été étudiées et décrites dans le site minier de Jerada : Coprinellus bipellis, C. xanthotrix, C. radians, Parasola plicatilis, Coprinopsis strossmayeri (Psathyrellaceae), C. comatus, (Agaricaceae). C. bipellis et C. strossmayeri sont nouvelles pour la flore fongique du Maroc. La position systématique, l’importance écologique, gastronomique et les conditions de la culture de ces espèces ont été discutées dans ce travail.Conclusion et application de la recherche : Les résultats obtenus s’intègrent dans la contribution à la détermination de la diversité fongique du Maroc, qui demeure jusqu’à présent incomplète.Mots clés : Maroc, Jerada, Basidiomycètes, Psathyrellaceae, Agaricaceae, diversité fongique.Study of some coprinoid fungi in the domanial forest of the Jerada mine site (Northeast of Morocco) whose Coprinellus bipellis and Coprinopsis strossmayeri are new to the fungal flora of MoroccoObjective: The present work aims to study the fungal flora of the forest of Beni Yaala mine site Jerada (northeastern Morocco).Methodology and results: The surveys conducted in the study area were used to record information on fungal species encountered. In the laboratory, macroscopic and microscopic criteria for identifying these species were determined. Six species of Basidiomycetes macromycetes were studied and described in the mining site Jerada: Coprinellus bipellis, C. xanthotrix, C. radians, Parasola plicatilis, Coprinopsis strossmayeri (Psathyrellaceae), C. comatus (Agaricaceae). C. bipellis  and C. strossmayeri are new to the fungal flora of Morocco. The systematic position, the ecological, gastronomical and conditions of cultivation of these species have been discussed in this work.Conclusion and application of research: The results are part of the contribution to the determination of the fungal diversity of Morocco, which remains incomplete until nowKeywords: Morocco, Jerada, Basidiomycetes, Psathyrellaceae, Agaricaceae, fungal diversity

Y Chromosome Lineages in Men of West African Descent

The early African experience in the Americas is marked by the transatlantic slave trade from ~1619 to 1850 and the rise of the plantation system. The origins of enslaved Africans were largely dependent on European preferences as well as the availability of potential laborers within Africa. Rice production was a key industry of many colonial South Carolina low country plantations. Accordingly, rice plantations owners within South Carolina often requested enslaved Africans from the so-called ‘‘Grain Coast’’ of western Africa (Senegal to Sierra Leone). Studies on the African origins of the enslaved within other regions of the Americas have been limited. To address the issue of origins of people of African descent within the Americas and understand more about the genetic heterogeneity present within Africa and the African Diaspora, we typed Y chromosome specific markers in 1,319 men consisting of 508 west and central Africans (from 12 populations), 188 Caribbeans (from 2 islands), 532 African Americans (AAs from Washington, DC and Columbia, SC), and 91 European Americans. Principal component and admixture analyses provide support for significant Grain Coast ancestry among African American men in South Carolina. AA men fromDC and the Caribbean showed a closer affinity to populations from the Bight of Biafra. Furthermore, 30–40% of the paternal lineages in African descent populations in the Americas are of European ancestry. Diverse west African ancestries and sexbiased gene flow from EAs has contributed greatly to the genetic heterogeneity of African populations throughout the Americas and has significant implications for gene mapping efforts in these populations

Partitions of Y chromosome molecular variance.

<p> <b>Φ_ST = Within populations; Φ_CT = Among groups; Φ_SC = Among populations within groups; %V = Percent of the variance.</b></p

Expansion Times of West African Y Chromosome Groups.

<p>Expansion Times of West African Y Chromosome Groups.</p

Estimates of European paternal ancestry (%) in African descent populations in the Americas.

<p>Estimates of European paternal ancestry (%) in African descent populations in the Americas.</p

Plot of the first two principal components of a Y chromosome genetic distance matrix estimated for 17 populations.

<p>Plot of the first two principal components of a Y chromosome genetic distance matrix estimated for 17 populations.</p