Lagunage naturel de lixiviat de décharge

Dans le cadre d'un traitement par lagunage naturel des lixiviats d'une décharge d'ordures ménagères broyées, nous avons procédé au cours d'un cycle annuel (mai 1998 à mai 1999) à des analyses biologiques et physicochimiques des eaux à l'entrée (lixiviat brut), dans les quatre bassins successifs et à la sortie du dispositif (lixiviat traité) avant son rejet dans le milieu récepteur (ruisseau Mont Bonnet). L'évolution spatiotemporelle de la qualité des lixiviats a été approchée par le suivi des fluctuations saisonnières de divers paramètres (température, conductivité électrique, pH, oxygène dissous, potentiel redox, chlorures, fer, manganèse, nickel, zinc, azote total, phosphore total, ammonium, DBO, DCO et chlorophylle a). Les résultats montrent deux périodes de dysfonctionnement de la station durant l'année. Un dysfonctionnement estival marqué par une chute du rendement épuratoire du fer, du manganèse et de la DBO, sous l'effet d'une diminution du potentiel redox et du surplus de matières organiques autochtones. Le deuxième dysfonctionnement, observé en hiver et au début du printemps, est caractérisé par une chute des rendements épuratoires pour l'ensemble des éléments chimiques suivis. Cette chute des rendements épuratoires est vraisemblablement liée à la diminution importante des valeurs de pH durant cette période.The Etueffont municipal landfill waste (Northeast of Belfort, France) possesses a mode of exploitation by grinding wastes without compaction, to facilitate the aerobic degradation. This technique leads to a leachate production. The leachate was treated by natural lagoons consisting of 4 decantation basins then released in the brook (of Mont Bonnet). Efficiency of the epuration was estimated by calculation the net budget of elements (=Input-Output). The results showed that lagoons eliminated the quasi-totality of organic matters (about 80% of BOD) and dissolved substances (about 50 to 90%). Nevertheless, a decrease of epuration efficiency that has been observed in winter of all elements (temperature, electric conductivity, pH, dissolved oxygen, redox potential, chloride, iron, manganese, nickel, zink, total nitrogen, total phosphorus, ammonia, BOD, COD), was due to the decrease of pH (pH=4,5). However, in the begining of summer only Cu2+ and Fe2+ decreased. The collapse of BOD removel (- 8% observed in September 1998) was linked to the excedentary stock of organic matter products in the basins during the summer. The analysis of the monthly evolution of the efficiency epuration of NH4+, total nitrogen (TN) and total phosphorus (TP) indicate similary features. The net budget fluctuates between 50% in winter and 70% in summer. The weak values are noted in January 1999 (19% for NH4+ , 13% for TN and 14% for TP). This work showed that the natural lagooning is weakly efficient for this kind of landfill leachates

Carcinome muco-épidermoide chez une jeune fille de 21 ans

Les carcinomes muco-épidermoïdes font partie d’un groupe rare de tumeurs pulmonaires malignes. Ces tumeurs sont le plus souvent retrouvées chez lessujets jeunes. La croissance de la tumeur est en général endo-bronchique et concerne les bronches de grande taille. L’aspect histo-pathologique révèle des cellules produisant du mucus, des cellules épithéliales et des cellules mixtes. Dans cet article nous rapportons l’observation d’une jeune fille de 21 ans avec une tumeur de la bronche souche droite, qui après résection endo-bronchique s’est avéré être un carcinome muco-épidermoïde pulmonaire. La patiente a subi une pneumonectomie droite élargie à la carène avec un curage ganglionnaire médiastinale. Elle est actuellement en rémission après un suivi de 7 mois. Aucun traitement standard n’est défini pour ces tumeurs. Le pronostic dépend du grade histologique, et peut, notamment chez les sujets âgés, être très péjoratif

Characterization of an extracellular lipase and its chaperone from Ralstonia eutropha H16

Lipase enzymes catalyze the reversible hydrolysis of triacylglycerol to fatty acids and glycerol at the lipid–water interface. The metabolically versatile Ralstonia eutropha strain H16 is capable of utilizing various molecules containing long carbon chains such as plant oil, organic acids, or Tween as its sole carbon source for growth. Global gene expression analysis revealed an upregulation of two putative lipase genes during growth on trioleate. Through analysis of growth and activity using strains with gene deletions and complementations, the extracellular lipase (encoded by the lipA gene, locus tag H16_A1322) and lipase-specific chaperone (encoded by the lipB gene, locus tag H16_A1323) produced by R. eutropha H16 was identified. Increase in gene dosage of lipA not only resulted in an increase of the extracellular lipase activity, but also reduced the lag phase during growth on palm oil. LipA is a non-specific lipase that can completely hydrolyze triacylglycerol into its corresponding free fatty acids and glycerol. Although LipA is active over a temperature range from 10 °C to 70 °C, it exhibited optimal activity at 50 °C. While R. eutropha H16 prefers a growth pH of 6.8, its extracellular lipase LipA is most active between pH 7 and 8. Cofactors are not required for lipase activity; however, EDTA and EGTA inhibited LipA activity by 83 %. Metal ions Mg[superscript 2+], Ca[superscript 2+], and Mn[superscript 2+] were found to stimulate LipA activity and relieve chelator inhibition. Certain detergents are found to improve solubility of the lipid substrate or increase lipase-lipid aggregation, as a result SDS and Triton X-100 were able to increase lipase activity by 20 % to 500 %. R. eutropha extracellular LipA activity can be hyper-increased, making the overexpression strain a potential candidate for commercial lipase production or in fermentations using plant oils as the sole carbon source.Malaysia-MIT Biotechnology Partnership Programm

Intrauterine Growth Retarded Progeny of Pregnant Sows Fed High Protein:Low Carbohydrate Diet Is Related to Metabolic Energy Deficit

High and low protein diets fed to pregnant adolescent sows led to intrauterine growth retardation (IUGR). To explore underlying mechanisms, sow plasma metabolite and hormone concentrations were analyzed during different pregnancy stages and correlated with litter weight (LW) at birth, sow body weight and back fat thickness. Sows were fed diets with low (6.5%, LP), adequate (12.1%, AP), and high (30%, HP) protein levels, made isoenergetic by adjusted carbohydrate content. At −5, 24, 66, and 108 days post coitum (dpc) fasted blood was collected. At 92 dpc, diurnal metabolic profiles were determined. Fasted serum urea and plasma glucagon were higher due to the HP diet. High density lipoprotein cholesterol (HDLC), %HDLC and cortisol were reduced in HP compared with AP sows. Lowest concentrations were observed for serum urea and protein, plasma insulin-like growth factor-I, low density lipoprotein cholesterol, and progesterone in LP compared with AP and HP sows. Fasted plasma glucose, insulin and leptin concentrations were unchanged. Diurnal metabolic profiles showed lower glucose in HP sows whereas non-esterified fatty acids (NEFA) concentrations were higher in HP compared with AP and LP sows. In HP and LP sows, urea concentrations were 300% and 60% of AP sows, respectively. Plasma total cholesterol was higher in LP than in AP and HP sows. In AP sows, LW correlated positively with insulin and insulin/glucose and negatively with glucagon/insulin at 66 dpc, whereas in HP sows LW associated positively with NEFA. In conclusion, IUGR in sows fed high protein∶low carbohydrate diet was probably due to glucose and energy deficit whereas in sows with low protein∶high carbohydrate diet it was possibly a response to a deficit of indispensable amino acids which impaired lipoprotein metabolism and favored maternal lipid disposal

Properties, production, and applications of camelid single-domain antibody fragments

Camelids produce functional antibodies devoid of light chains of which the single N-terminal domain is fully capable of antigen binding. These single-domain antibody fragments (VHHs or Nanobodies®) have several advantages for biotechnological applications. They are well expressed in microorganisms and have a high stability and solubility. Furthermore, they are well suited for construction of larger molecules and selection systems such as phage, yeast, or ribosome display. This minireview offers an overview of (1) their properties as compared to conventional antibodies, (2) their production in microorganisms, with a focus on yeasts, and (3) their therapeutic applications