Structure/functional properties of the yeast dual regulator protein NGG1 that are required for glucose repression.

NGG1p/ADA3p is a yeast dual function regulator required for the complete glucose repression of GAL4p-activated genes (Brandl, C. J., Furlanetto, A. M., Martens, J. A., and Hamilton, K. S. (1993) EMBO J. 12, 5255-5265). Evidence for a direct role for NGG1p in regulating activator function is supported by the finding that NGG1p is also required for transcriptional activation by GAL4p-VPl6 and LexA-GCN4p (Pina, B., Berger, S. L., Marcus, G. A., Silverman, N., Agapite, J., and Guarente, L. (1993) Mol. Cell. Biol. 13, 5981-5989). By analyzing deletion derivatives of the 702-amino acid protein, we identified a region essential for glucose repression within residues 274-373. Essential sequences were further localized to a segment rich in Phe residues that is predicted to be an amphipathic alpha helix. As well as finding mutations within this region that reduced glucose repression, we identified mutations that made NGG1p a better repressor. In addition, NGG1p probably represses GAL4p activity as part of a complex containing ADA2p because single and double disruptions of ngg1 and ada2 had comparable effects on glucose repression. We also localized a transcriptional activation domain within the amino-terminal amino acids of NGG1p that is proximal or overlapping the region required for glucose repression. Activation by GAL4p-NGG1p(1-373) requires ADA2p; however, activation by GAL4p-NGG1p(1-308), is ADA2p-independent. This suggests that a site required for ADA2p interaction lies between amino acids 308 and 373 and that ADA2p has a regulatory role in activation by GAL4p-NGG1p(1-373).

The LonStenn-a new cervical sampling device.

A new cervical sampling device, the 'LonStenn' was evaluated against devices in common use: the Cervex Brush, and the CytoBrush plus Ayres Spatula, by comparing the number of cells removed from the cervix and the number released from the device onto a glass slide. One hundred and eighty patients were studied. Ninety patients had Papanicolaou (Pap) smears, and at the same examination, colposcopy and biopsies, with 30 patients being allocated to each of the three sampling methods. After the plating of the Pap smear, the 'head' of the device was cut off and placed in a vial of Tyrode saline solution and vortexed. The residual cells remaining in the saline solution were counted in a Kova Slide Chamber. This allowed assessment of one possible cause of false negatives (ie, cell entrapment). A control group of 90 patients, with 30 allocated to each device, had Pap smears taken which were not plated out: the head of the device was removed and again placed in Tyrode saline solution. The cells harvested from the cervix were counted by the same method as before. The subtraction of the cells from the plated-out group from the control (nonplated out) group gave an indication of the number of cells delivered to the slide for cytological evaluation. The LonStenn is shown to be more efficient in its quantitative delivery of representative harvested cells from the cervix to a glass slide for cytological analysis. Qualitative assessment of smears prepared from this device suggested an improvement, as indicated by less blood staining. This should also ultimately be reflected by a decrease in false negatives in the laboratory.