Characterisation of MHC class II DRB genes in the northern tree shrew (Tupaia belangeri)

Genes of the major histocompatibility complex (MHC) mainly code for proteins of the immune system of jawed vertebrates. In particular, MHC class I and II cell surface proteins are crucial for the self/non-self discrimination of the adaptive immune system and are the most polymorphic genes in vertebrates. Positive selection, gene duplications and pseudogenes shape the face of the MHC and reflect a highly dynamic evolution. Here, we present for the first time data of the highly polymorphic MHC class II DRB exon 2 of a representative of the mammalian order scandentia, the northern tree shrew Tupaia belangeri. We found up to eight different alleles per individual and determined haplotype constitution by intensively studying their inheritance. The alleles were assigned to four putative loci, all of which were polymorphic. Only the most polymorphic locus was subject to positive selection within the antigen binding sites and only alleles of this locus were transcribed.     

Rheological properties of cross-linked hyaluronan-gelatin hydrogels for tissue engineering

Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component.     

Effects on product formation in Lactococcus lactis 65.1 in continuous culture with complete cell recycling

Lactococcus lactis 65.1 was cultivated in a batch culture, which underwent starvation for 3 days, continuous culture and continuous culture with complete cell recycling. The objective was to study the product formation and intracellular protein pattern. Changes from homofermentative to heterofermentative metabolism were observed in continuous culture at the lower dilution rates as well as continuous cultures with complete cell recycling at a fixed dilution rate (D=0.4 h^–1). Changes in intracellular protein pattern were observed when starving the cells in a batch culture and also when recycling the cells in a continuous culture. Some changes were the same in these two cases. The data collected from these experiments show how the fermentation technique can affect the products of the microorganism being cultured and gives some interesting information on the complete cell recycling technique, which is of great interest in fermentation processes.