44 research outputs found
Overexpression of the Aspergillus niger GatA transporter leads to preferential use of D-galacturonic acid over D-xylose
No full textPectin is a structural heteropolysaccharide of the primary cell walls of plants and as such is a significant fraction of agricultural waste residues that is currently insufficiently used. Its main component, D-galacturonic acid, is an attractive substrate for bioconversion. The complete metabolic pathway is present in the genome of Aspergillus niger, that is used in this study. The objective was to identify the D-galacturonic acid transporter in A. niger and to use this transporter to study D-galacturonic acid metabolism. We have functionally characterized the gene An14g04280 that encodes the D-galacturonic acid transporter in A. niger. In a mixed sugar fermentation it was found that the An14g04280 overexpression strain, in contrast to the parent control strain, has a preference for D-galacturonic acid over D-xylose as substrate. Overexpression of this transporter in A. niger resulted in a strong increase of D-galacturonic acid uptake and induction of the D-galacturonic acid reductase activity, suggesting a metabolite controlled regulation of the endogenous D-galacturonic acid catabolic pathway
Overexpression of the Aspergillus niger GatA transporter leads to preferential use of D-galacturonic acid over D-xylose
No full textPectin is a structural heteropolysaccharide of the primary cell walls of plants and as such is a significant fraction of agricultural waste residues that is currently insufficiently used. Its main component, D-galacturonic acid, is an attractive substrate for bioconversion. The complete metabolic pathway is present in the genome of Aspergillus niger, that is used in this study. The objective was to identify the D-galacturonic acid transporter in A. niger and to use this transporter to study D-galacturonic acid metabolism. We have functionally characterized the gene An14g04280 that encodes the D-galacturonic acid transporter in A. niger. In a mixed sugar fermentation it was found that the An14g04280 overexpression strain, in contrast to the parent control strain, has a preference for D-galacturonic acid over D-xylose as substrate. Overexpression of this transporter in A. niger resulted in a strong increase of D-galacturonic acid uptake and induction of the D-galacturonic acid reductase activity, suggesting a metabolite controlled regulation of the endogenous D-galacturonic acid catabolic pathway
EBY.VW4000 <i>rhaA</i><sup>+</sup> and CEN.PK2-1C <i>rhaA</i><sup>+</sup> growth inhibition assays.
No full texta) Growth of yeast strains CEN.PK2-1C and EBY.VW4000 expressing the rhtA gene on minimal medium with maltose (M; 29 mM), D-fructose (F; 28 mM) or D-fructose (F; 28 mM) supplemented with L-rhamnose (R; 0.06 mM); b) Growth of EBY.VW4000 rhaA+ on minimal medium containing D-fructose (F; 28 mM) or D-fructose (F; 28 mM) supplemented with L-fucose (Fc; 6.1 mM) or 2-deoxy-D-ribose (Dr; 6.1 mM).</p
RhtA functional analysis in yeast.
No full textGrowth of strain EBY.VW4000 expressing the rhtA gene (rhtA+) or harbouring the empty expression vector p426HXT7-6His (EV) in minimal medium agar plates containing maltose (M; 29 mM), D-glucose (G; 56 mM), D-fructose (F; 56 mM) or D-mannose (Mn; 56 mM) as sole carbon sources. Agar plates were incubated at 30°C for 96 h. Transformants expressing RhtA showed the same growth pattern; the figure depicts only one representative transformant.</p
EBY.VW4000 <i>rhaA</i><sup>+</sup> growth inhibition assays.
No full texta) Growth of yeast strain EBY.VW4000 expressing the rhtA gene on minimal medium with maltose (M; 29 mM), D-fructose (F; 28 mM), and D-fructose (F; 28 mM) supplemented with the potentially competing carbon sources: D-glucose (G; 56 mM and 5.6 mM), D-xylose (X; 66 mM and 6.6 mM), L-arabinose (A; 66 mM and 6.6 mM), D-sorbitol (S; 55 mM and 5.5 mM) or L-rhamnose (R; 61 mM and 6.1 mM); b) growth of yeast strain EBY.VW4000 expressing the rhtA gene on minimal medium with D-fructose (F; 28 mM), and D-fructose (F; 28 mM) supplemented with a range of L-rhamnose concentrations (0.0006 mM to 6.1 mM).</p
Functional characterization of <i>A</i>. <i>niger</i> RhtA sugar transporter.
No full textUptake at high cell density of radiolabeled substrates by S. cerevisiae EBY.VW4000 expressing the Aspergillus niger L-rhamnose transporter gene rhtA (black bars) or D-xylose transporter gene xltB (open bars). Radiolabeled L-rhamnose, D-xylose or D-fructose were added at a final concentration of 20 μM.</p
Transcriptional analysis of <i>rhtA</i>.
No full textRelative transcription levels were measured by RT-qPCR, in A. niger N400 sampled 2 hours after mycelium transfer to minimal medium with 100 mM D-sorbitol (reference), 5 mM L-rhamnose or 5 mM D-fructose. Transcript levels are relative to reference sample (D-sorbitol 100 mM), indicated with an asterisk. Results are given as relative transcript ratios in logarithmic scale (lg(10)). The values provided in the figures correspond to two biological replicates per culture condition. Error bars are means of three technical replicates.</p
Perineal hernia repair after abdominoperineal resection: a pooled analysis
No full textAim The purpose of this study was to determine treatment characteristics and clinical outcome for patients with perineal hernia after abdominoperineal excision (APE). Method A systematic search of the literature revealed 40 individually documented patients, published between 1944 and 2010. Three additional patients treated at our centre were added. Patient characteristics, type of repair and outcome were entered into a database and a pooled analysis of these 43 patients was performed. Results The pooled analysis revealed a median time interval of 8 months between APE and surgical repair of perineal hernia. The surgical approaches were perineal in 22 patients, open abdominal in 11, open abdominoperineal in three, laparoscopic in five and laparoscopic-perineal in two patients. A primary recurrence was documented in 13 patients and a second recurrence in three. The recurrence rate was 5/25 for synthetic or biological mesh, 6/12 for primary closure and 2/6 for the remaining techniques. Recurrent perineal hernia was repaired using a synthetic or biological mesh (n = 6), primary closure (n = 5) or a muscle flap (gluteus or gracilis; n = 4). Conclusion From these limited and biased data based on published case descriptions, it appears that the recurrence rate of primary perineal hernia repair after APE is lower with the use of a mesh or other assisted closure than with primary suture repai
Treatment of chronic presacral sinus after low anterior resection
No full textThe aim of this retrospective study was to determine patient and treatment characteristics with corresponding clinical outcome of symptomatic chronic presacral sinus after low anterior resection. Twenty-two patients were treated for a presacral sinus persisting for at least 12 months after low anterior resection for rectal carcinoma between January 2005 and March 2012. Patient charts were reviewed and analysed using descriptive statistics. Fistula formation was the most frequently observed secondary complication in 55% of patients. A median of 6 (1-44) surgical, endoscopic or radiological interventions related to the presacral sinus were performed. Overall, the chronic presacral sinus healed after multimodality treatment in nine (41%) patients at a median interval from primary surgery of 45 (24-93) months. If basic treatment principles were followed (anastomotic reconstruction or completion proctectomy with filling of the cavity), healing rate of the sinus was higher than where these principles were not adhered to (62% vs 11%). Successful treatment of a chronic presacral sinus after low anterior resection appears to be achieved by salvage surgery with anastomotic reconstruction in highly selected patients or intersphincteric completion proctectomy and omentoplast
