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Carvalhal A.V.,Institute Of Biologia Experimental E Tecnologica | Carvalhal A.V.,University of Lisbon | Santos S.S.,Institute Of Biologia Experimental E Tecnologica | Carrondo M.J.T.,Instituto Of Biologia Experimental E Tecnologica | Carrondo M.J.T.,New University of Lisbon
Biotechnology Progress | Year: 2011

The presence of purines and pyrimidines bases, nucleosides, and nucleotides in the culture medium has shown to differently affect the growth of a Chinese hamster ovary (CHO) cell line producing the secreted form of the human placental alkaline phosphatase enzyme (SEAP; Carvalhal et al., Biotech Prog. 2003;19:69-83). CHO, BHK, as well as Sf9 cell growth was clearly reduced in the presence of purines but was not affected by pyrimidines at the concentrations tested. The knowledge about the mechanisms by which nucleotides exert their effect when present outside the cells remains very incomplete. The catabolism of both extracellular purines and pyrimidines was followed during the culture of CHO cells. Purines/pyrimidines nucleotides added at a concentration of 1 mM to the culture medium decreased to negligible concentrations in the first 2 days. Purine and pyrimidine catabolism originated only purinic and pyrimidic end-products, respectively. The comparison between AMP catabolism in serum-free cultures (CHO cells expressing Factor VII and Sf9 cells) and in cultures containing serum (CHO cells expressing SEAP and BHK cells expressing Factor VII) showed that AMP extracellular catabolism is mediated by both cells and enzymes present in the serum. This work shows that the quantification of purines and pyrimidines in the culture medium is essential in animal cell culture optimization. When using AMP addition as a chemical cell growth strategy for recombinant protein production improvement, AMP extracellular concentration monitoring allows the optimization of the multiple AMP addition strategy for a prolonged cell culture duration with high specific productivity. © 2011 American Institute of Chemical Engineers (AIChE). Source


Santos R.D.,New University of Lisbon | Rocha A.,IBB Institute for Biotechnology And Bioengineering | Matias A.,Instituto Of Biologia Experimental E Tecnologica | Duarte C.,Instituto Of Biologia Experimental E Tecnologica | And 4 more authors.
RSC Advances | Year: 2013

We report a method to obtain electrospun fibers based on ionic liquids and gelatin, exhibiting antimicrobial properties. © 2013 The Royal Society of Chemistry. Source


Pereira A.L.,University of Porto | Pereira A.L.,University of Lisbon | Martins M.,Institute Medicina Molecular | Martins M.,Instituto Of Biologia Experimental E Tecnologica | And 3 more authors.
Plant Systematics and Evolution | Year: 2011

Family Azollaceae has seven species with a controversial taxonomy. The identification of species without reproductive structures relies on vegetative characters but some are variable, leading to misinterpretations. The molecular methods may be helpful, but until now, they did not provide a conclusive Azolla taxonomy. Therefore, we studied the family Azollaceae at vegetative and molecular levels. Analysis of vegetative, random amplified polymorphic DNA (RAPD) and combined data showed a comparable grouping of the Azolla species in two main clusters: cluster I, referred to as section Rhizosperma (A. pinnata and A. nilotica) and cluster II, referred to as section Azolla (A. filiculoides, A. microphylla, A. caroliniana and A. mexicana), with the exception of A. rubra, which clustered differently depending on the method. All the Azolla species were distinguished by the 13 polymorphic vegetative characters, the 211 RAPD markers or the combined data, with the latest showing the highest discrimination. The Shannon Index diversity was greater with RAPD (2.276) than with vegetative characters (0.054), highlighting the higher discriminating power of the molecular data. The partitioning of diversity was, as expected, high among species for all the types of data and low within species, with the lowest diversity obtained for morphological data. Both data sets (vegetative and RAPD) allowed the distinction of all the species and their clustering into sections Rhizosperma and Azolla, suggesting this as the most correct for this family. The dendrogram from the combined data was the most accurate, highlighting the benefit of integrating different types of data to study the family Azollaceae. © 2011 Springer-Verlag. Source

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