Studies on picophytoplankton in the southern Gulf of Mexico: recognition of picoprokaryotes and abundances of picophytoplankton during "dry season"

The abundance and distribution of total autotrophic picophytoplankton (PFP), temperature, salinity, PAR, and chlorophyll a were determined in two presumably contrasting environments: (1) two coastal areas (close to the mouths of three rivers), and (2) one oceanic area (Campeche Canyon), of the southern Gulf of Mexico, during the "dry season" (June-July, 2004). The picoprokaryotes Prochlorococcus and Synechococcus were identified by TEM, whereas Synechococcus and picoeukaryotes populations were also recognized by flow cytometry. The highest PFP abundance (1.67×105 cells ml-1) was found in shallow waters (~10 m depth) around the Grijalva-Usumacinta river mouth, followed by that found at a station close to the Coatzacoalcos River (1.19×105 cells ml-1); PFP abundances in the Campeche Canyon were usually lower (maximum 1.53×104 cells ml-1). Greater variability in PFP abundances was found in coastal stations than in oceanic waters, and weak relationships appeared between the patterns of chlorophyll a and PFP abundance. Peaks of PFP were detected in both coastal and more oceanic areas, but in the Campeche Canyon they were located deeper (60 m), relatively closer to the deep maximum of chlorophyll (located at about 75 m). Results suggest that PFP populations include a substantial photosynthetic component in both coastal and oceanic waters of the southern Gulf of Mexico.Abundância e distribuição do picofitoplâncton autotrófico total (PFP), temperatura, salinidade, PAR e clorofila-a, foram determinados em dois ambientes presumivelmente diferentes: (1) duas áreas costeiras (perto da foz de três rios) e (2) uma área oceânica (Campeche Canyon), ambas situadas ao sul do Golfo do México, durante a "estação seca" (Junho-Julho, 2004). Os picoprocariontes Prochlorococcus e Synechococcus foram identificados por TEM, e as populações de Synechococcus e de picoeucariontes também foram reconhecidas por citometria de fluxo. A maior abundância de PFP (1,67 × 105 células ml-1) foi encontrada em águas rasas (~ 10 m de profundidade) em torno dos rios Grijalva Usumacinta, seguida de uma estação perto do Rio Coatzacoalcos (1,19 × 105 células ml-1). As abundâncias de PFP em Campeche Canyon foram geralmente menores (máximo 1,53 × 104 células ml-1). A maior variabilidade em abundâncias de PFP foi encontrada em estações costeiras quando comparado às águas oceânicas, e quase não houve correlação entre os padrões de clorofila-a e abundância de PFP. Picos de PFP foram detectados nas áreas costeiras e oceânicas, mas em Campeche Canyon localizaram-se em maior profundidade (60 m), relativamente mais perto do local onde se registrou o máximo de clorofila (cerca de 75 m). Os resultados sugerem que as populações de PFP englobam um componente fotossintético substancial em ambas as águas costeiras e oceânicas do sul do Golfo do México

Identification and characterization of mechanistically distinct inducers of gamma-globin transcription

Inhibition of HbS polymerization is a major target for therapeutic approaches in sickle cell anemia. Toward this goal, initial efforts at pharmacological elevation of fetal hemoglobin (HbF) has sh

Apport du scanner osseux fœtal et de l'échographie dans le bilan étiologique d'un fémur court diagnostiqué in utéro

Introduction : en période anténatale, la détection d’un fémur court peut-être l’expression précoce et isolée d’une Maladie Osseuse Constitutionnelle (MOC). Les données actuelles de la littérature considèrent l’échographie et la tomodensitométrie comme complémentaires pour le diagnostic d’une MOC, mais de faible niveau de preuve. Les objectifs de notre étude étaient d’évaluer la performance de ces deux examens en anténatal pour le diagnostic d’une MOC en cas de fémur court in utéro, de déterminer les seuils de longueur fémorale échographique pertinents pour le diagnostic d’une dysplasie osseuse et pour la détection d’une anomalie génétique à l’amniocentèse, et de décrire le devenir des enfants.Matériels et méthodes : une étude rétrospective multicentrique a été menée au sein de deux Centres Pluridisciplinaires de Diagnostic Prénatal (CPDPN) dans un même Centre Hospitalier Universitaire (CHU) sur une période de 7 ans, du 01/01/2011 au 31/12/2017. Les critères d’inclusion étaient les patientes ayant bénéficié d’une tomodensitométrie du squelette fœtal pour fémur inférieur au 5e percentile après expertise par un échographe référent au CPDPN et dont le diagnostic fœtal ou néonatal était avéré. Résultats : parmi les 184 patientes ayant eu une tomodensitométrie du squelette fœtal, cent-treize ont été incluses. L’échographie et la tomodensitométrie présentaient respectivement une sensibilité de 76.1% (Intervalle de Confiance [IC] 95%, 63.8-88.4%) et 95.7% (IC 95%, 89.8-101.5), et une spécificité de 91.0% (IC 95%, 84.2-97.9) et 94.0% (IC 95%, 88.4-99.7) pour le diagnostic d’une MOC. Un seuil de -3.83 pour le Z-score fémoral et un seuil de 4.14 semaines d’aménorrhée de décalage sur la longueur fémorale échographique étaient retenus comme des seuils pertinents dans la détection d’une MOC, avec des aires sous la courbe, respectives de 0.84 (0.76-0.92) pour le Z-score et 0,70 (0.60-0.80) pour les semaines d’aménorrhée. Un seuil de 3.90 pour le Z-score fémoral était calculé comme déterminant pour la détection d’une anomalie génétique à l’amniocentèse avec une aire sous la courbe de 0.70 (0.52-0.88). Un suivi moyen à 57,6 mois (± 26,5) était disponible pour 81 enfants.Conclusion : l’échographie et la tomodensitométrie anténatales sont des examens performants dans le diagnostic d’une MOC après détection d’un fémur inférieur au 5e percentile. Les seuils échographiques de longueur fémorale calculés dans notre analyse pourraient présenter une aide à l’indication de la tomodensitométrie et de l’amniocentèse

Noncovalent Inhibitors of Sickle Hemoglobin Gelation: Effects of Aryl-Substituted Alanines

The effects of 42 β-aryl-substituted alanines on the inhibition of gelation of sickle hemoglobin (Hb S) were evaluated. These included 18 derivatives of phenylalanine, 16 derivatives of tryptophan, and 4 analogues of each of these aromatic amino acids. Among the para-halogen-substituted phenylalanine derivatives, the order of molar effectiveness in increasing the solubility of deoxy-Hb S was I ∼ Br \u3e CI \u3e F; substituents at the equivalent 5 position of the indole ring of tryptophan gave the order Br \u3e 0CH3 ∼ OH \u3e CH3 \u3e F. For three phenylalanine derivatives substituted on the alanyl side chain by a methyl group, the order was N-CH3 \u3e α-CH3 ≫ β-CH3. A similar situation prevailed for the N-CH3 and α-CH3 derivatives of tryptophan. For two other para-substituted phenylalanines the nitro derivative was more effective than the amino derivative by nearly 3-fold. For the analogues of phenylalanine, β-(1-naphthyl)alanine was 2.5 times more effective than β-(2-naphthyl)alanine, while β-(2-thienyl)alanine and β-(3-thienyl)alanine were equipotent and somewhat less effective than phenylalanine. All three analogues of tryptophan were more potent than the parent compound and showed the following order of effectiveness: 7-azaindol-3-yl \u3e 3-benzothienyl \u3e 3-benzofuranyl. From the overall results obtained, the following generalizations can be made regarding the efficacy of β-aryl-substituted alanines as noncovalent inhibitors of gelation: (1) bicyclic aromatic nuclei are considerably more potent than monocyclic ones and (2) the nature of the substituent at a fixed position on a particular aromatic ring exerts a profound effect on the expression of antigelling activity. The best gelation inhibitor to emerge from this comprehensive survey was 5-bromotryptophan, which was 5 times more effective than phenylalanine. By suitable manipulation of either the aromatic nucleus or the alanyl side chain, it should be possible to increase antigelling activity to a level potent enough to be useful in a therapy for sickle cell anemia. © 1982, American Chemical Society. All rights reserved