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Economical Means (economical + mean)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

De novo synthesis and assembly of multiplex riboswitches in vitro

BIOTECHNOLOGY PROGRESS, Issue 5 2009
Hao-Hua Sun
Abstract Pools of short synthetic oligonucleotides (oligos) are required in the multiplex and parallel DNA construction. Microarray technology provides a fast and economical mean for massive parallel synthesis of oligos. The method of oligo synthesis with the programmable microfluidic PicoArray could simultaneously synthesize the designed oligos for multiple riboswitch genes. The synthetic oligos were recovered and purified as a pool of oligo mixture (OligoMix). Three temperature steps were employed to denature, anneal and extend the designed OligoMix until, after multiple rounds of thermocycling, the riboswitches with the desired length are obtained. The OligoMix was amplified using this PCR-based technique and the flanking adapter segments were cleaved for following assembly. Based on these oligos derived from 197 riboswitch sequences, the method of simultaneous assembling multiplex riboswitches (SAMRs) showed high fidelity by sequence identification. The resultant error rate was determined to be 2.78,. With the templates from SAMRs, in vitro transcription was applied to produce milligram amounts of biologically active riboswitches. With the verification of biological activity based on the high specificity of recognizing small-molecule metabolites as well as the DNA sequence redivivus by RT-PCR, the assembled riboswitches can be used for further gene operation and biological application. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source]

Instrument-independent specification of the diffraction geometry and polarization state of the incident X-ray beam

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2009
Marc Schiltz
This work augments the proposal of Schwarzenbach & Flack [J. Appl. Cryst. (1989), 22, 601,605], who have advocated the use of a diffractometer-independent definition of the azimuthal angle , to specify the diffraction geometry of a Bragg reflection. It is here proposed that one additional angle ,, which is also based on a diffractometer-independent definition, is needed to encode the direction of linear polarization for those experiments where this quantity is of importance. This definition is then extended to the cases of partially and/or elliptically polarized X-ray beams, and the use of three normalized Stokes parameters, P1, P2 and P3, together with ,, is advocated in order to characterize exhaustively the polarization state of the incident beam. The conventions proposed here present a general, unambiguous and economical means of encoding the information about the diffraction geometry, without the need to record any further information about the instrument, crystal orientation matrix and goniometer angles. Data-processing software using these definitions to analyse polarization-dependent phenomena becomes instrument-independent and completely general. These methods have been implemented in the macromolecular phasing program SHARP for exploiting the polarization anisotropy of anomalous scattering in protein crystals. [source]

Biomethane production from starch and lignocellulosic crops: a comparative review

BIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 4 2010
Jean-Claude Frigon
Abstract The methane produced from the anaerobic digestion of organic wastes and energy crops represents an elegant and economical means of generating renewable biofuel. Anaerobic digestion is a mature technology and is already used for the conversion of the organic fraction of municipal solid wastes and excess primary and secondary sludge from waste-water treatment plants. High methane yield up to 0.45 m3 STP CH4/kg volatile solids (VS) or 12 390 m3 STP CH4/ ha can be achieved with sugar and starch crops, although these cultures are competing with food and feed crops for high-quality land. The cultivation of lignocellulosic crops on marginal and set-aside lands is a more environmentally sound and sustainable option for renewable energy production. The methane yield obtained from these crops is lower, 0.17,0.39 m3 STP CH4/kg VS or 5400 m3 STP CH4/ha, as its conversion into methane is facing the same initial barrier as for the production of ethanol, for example, hydrolysis of the crops. Intensive research and development on efficient pre-treatments is ongoing to optimize the net energy production, which is potentially greater than for liquid biofuels, since the whole substrate excepted lignin is convertible into methane. Copyright © 2010 Crown in the right of Canada [source]

Osmoprotective Effect of Glycine Betaine on Thrombopoietin Production in Hyperosmotic Chinese Hamster Ovary Cell Culture: Clonal Variations

BIOTECHNOLOGY PROGRESS, Issue 5 2000
Tae Kyung Kim
When 23 recombinant Chinese hamster ovary (rCHO) cell clones were cultivated in hyperosmolar medium resulting from NaCl addition (533 mOsm/kg), their specific thrombopoietin (TPO) productivity (qTPO) was increased. However, due to depressed cell growth at elevated osmolality, no enhancement in the maximum TPO titer was made in batch cultures of all 23 clones. To test the feasibility of using glycine betaine, known as a strong osmoprotective compound, for improved TPO production in hyperosmotic rCHO cell cultures, hyperosmotic batch cultures of 23 clones were performed in the presence of 15 mM glycine betaine. Glycine betaine was found to have a strong osmoprotective effect on all 23 clones. Inclusion of 15 mM glycine betaine in hyperosmolar medium enabled 22 clones to grow at 542 mOsm/kg, where most clones could not grow in the absence of glycine betaine, but at a cost of reduced qTPO. However, the relative decrease in qTPO varied significantly among clones. Thus, efficacy of the simultaneous use of hyperosmotic pressure and glycine betaine as a means to improve foreign protein production was variable among clones. Six out of 23 clones displayed more than a 40% increase in the maximum TPO titer in the hyperosmolar medium containing glycine betaine, compared with that in the standard medium with a physiological osmolality. Taken together, the results obtained here emphasize the importance of selection of clones for the successful use of hyperosmotic pressure and glycine betaine as an economical means to improve TPO production. [source]