Biomedical subjects
Publications and source records attributed to S Denslow.
The gene encoding the Vibrio proteolyticus aminopeptidase was cloned and sequenced and its amino acid sequence was deduced. The gene encodes a 54 kDa protein, larger than the previously reported size of 30 kDa for the purified aminopeptidase. Sequence alignments revealed a 43-45% homology with two other Vibrio sp. extracellular proteinases.
We have surveyed the amount and types of collagen synthesized in two regions of the chick heart during embryonic development. Cardiac tissues from successive periods of development were labeled with 3H-proline in short-term organ culture. The fraction of incorporated label present as collagen was estimated by comparison of TCA-soluble radioactivity before and after digestion with purified bacterial collagenase. This measure of collagen synthesis varied only slightly with the length of the labeling period and agreed with values obtained by labeling in ovo. In the developing outflow tract, the fraction of label present as collagen increased sharply during the period of truncal septation (5-9 days), rising from initial values of 6% at 3 days of incubation to a plateau of about 25% (10-19 days). In ventricular myocardium, this fraction rose gradually from 3 to 20% between 3 and 19 days of incubation. The types of collagen synthesized in developing heart were analyzed by limited pepsin digestion and acrylamide gel electrophoresis, using collagens synthesized in tendon, cartilage, skin, and lens capsule for comparison. The types of collagen synthesized in both cardiac regions changed in similar manner during development. During the first week of cardiac function, a substantial but progressively smaller fraction of total collagen synthesized was identified as Type IV. Synthesis of Type I collagen increased sharply during this period and predominated during the second half of development. Type III collagen was synthesized in trace amounts by the middle of development and constituted approximately one-sixth of total collagen synthesis just before hatching. Minor amounts of collagen identified as Type B collagen were synthesized throughout the latter two-thirds of development.
When tubulins obtained from particular microtubules of the sea urchin (ciliary doublet A tubules, flagellar doublet microtubules, and mitotic microtubules) are analyzed by electrophoresis in a polyacrylamide gel system containing sodium dodecyl sulfate and urea, heterogeneity of the alpha subunit, and differences between the tubulins are revealed. The alpha subunit of tubulin from mitotic apparatus and from A microtubules of ciliary doublets is resolved into two bands, while the alpha subunit of flagellar doublet tubulin gives a single band. The mitotic and ciliary tubulins differ in the mobilities of their two alpha species, or in the relative amounts present, or both. The existence of differences between the tubulins has been confirmed by a preliminary analysis of their cyanogen bromide peptides.