Identification of a transcriptional enhancer upstream from the bovine thyroglobulin gene.

The DNA sequences corresponding to a DNaseI-hypersensitive region identified previously in bovine thyroglobulin gene chromatin (Hansen et al. (1988) Eur. J. Biochem. 178, 387-393) exhibited the properties of a transcriptional enhancer in a transient assay in primary cultured dog thyrocytes, but did not so in transfected HeLa cells. By contrast to the thyroglobulin proximal promoter, the enhancer element did not require cyclic AMP stimulation of the thyrocytes to be active. Using a bi-directional deletion approach, the minimal region displaying enhancer activity has been localized between positions -1906 and -1744 relative to the thyroglobulin gene transcription start. DNA-footprinting experiments revealed the presence of several binding sites for the thyroid-specific transcription factor TTF-1 within the enhancer sequence.

Growth of macrophages obtained from various sources.

Techniques to obtain macrophages from various sources of the mouse were reported. The following sources were included: peritoneal exudate, alveolar lavage, blood leucocytes, bone marrow, spleen, liver, lungs, lymph nodes, thymus, thyroid, heart muscle, kidney, and subcutaneous cover glass implants. Human blood macrophages were also included. Long-term cinemicrographic studies revealed sustained good growth of these macrophages. Cell multiplication was detected in all of these cultures except those obtained from the peritoneal exudate. Pure cultures of macrophages were obtained from blood of the mouse and human. Macrophages obtained from other sources were accompanied by some growth of fibroblasts. Methods to eliminate the fibroblasts in cultures were discussed.