Tight junctions and apical/basolateral polarity

Summary Physiological studies led to devise models of epithelial cells in which the membrane does not have its molecules distributed homogeneously, but polarized towards the apical or towards the basolateral regions. For a while, it was assumed that the TJ, acting as a fence between the two regions, would be responsible for this asymmetry. However, today the information available indicates not only that polarization may proceed independently of the TJ, but that this structure itself may attain its precise location due to a polarization process. Nevertheless, TJs may play a role in restricting to the apical or to the basolateral region those molecules that are free to diffuse in the plane of the cell membrane (e.g., lipids and protein that are not attached to cytoplasmic or extracellular structures).     

Inducible Amplification of Gene Copy Number and Heterologous Protein Production in the Yeast Kluyveromyces lactis

Heterologous protein production can be doubled by increasing the copy number of the corresponding heterologous gene. We constructed a host-vector system in the yeast Kluyveromyces lactis that was able to induce copy number amplification of pKD1 plasmid-based vectors upon expression of an integrated copy of the plasmid recombinase gene. We increased the production and secretion of two heterologous proteins, glucoamylase from the yeast Arxula adeninivorans and mammalian interleukin-1β, following gene dosage amplification when the heterologous genes were carried by pKD1-based vectors. The choice of the promoters for expression of the integrated recombinase gene and of the episomal heterologous genes are critical for the mitotic stability of the host-vector system.     

The challenge of health care provision: A case study from Mexico

Lorenza Menegoni has a doctorate in Anthropology from the Graduate Faculty, The New School for Social Research, New York City. She is continuing her research in Mexico. Carmen Hendershott has a doctorate in Anthropology from the Graduate Faculty, The New School for Social Research, where she is working as a research librarian.