Bryozoa

The bryostatins are a family of macrolide lactones isolated from the
marine bryozoan Bugu/a neritina. Since its detection in 1968, bryostatin 1
has demonstrated remarkable anticancer, immunopotentiating,
biomodulatory and radioprotective effects which result mainly from its
ability to activate protein kinase C, a family of isozymes involved in cellular
signal transduction. It is currently being tested in several phase I and phase
II clinical trials as a potential anticancer drug for leukemia, melanoma and
nephrotoma. A series of experiments was undertaken to elucidate the
biosynthetic origins of bryostatin, using a fortified crude cell-free enzyme
preparation and radiolabelled precursors. A regional characterization of
Bugula neritina from Sicily, Italy and Daytona Beach, Florida is also
described.

The fatty acid synthetase (FAS) from the marine invertebrate Bugula neritina was isolated using cold ethanol precipitation followed by the sequence of G-100 and G-200 size exclusion columns. Native gel analysis indicates the isolation of the FAS and the elution volume from the G-100 column suggests the FAS to be ~282kd. One band with a molecular weight of 66 kDa appeared on the SDS gel of the G-200 sample (F17-30) that eluted at 52.5 mL. The G-200 sample that eluted at 19.2 mL (F1-6) displayed two predominant bands on the SDS gel corresponding to molecular weights 66 kDa and 97 kDa. Both F1-6 and F17-30 showed FAS activity displaying de novo production of myristic and palmitic acids. From the sequence of purification starting from the cell-free extract (CFE) to the F17-30 sample, a 240 fold increase in specific activity was observed. The Type II FAS experiments showed no substantial evidence of activity, namely of the beta-Hydroxybutyryl acyl-dehydrase and the enoyl reductase enzymes.

Bryostatin 1 is a macrocyclic lactone isolated from the marine bryozoan Bugula neritina. It is currently in clinical trials at the National Cancer Institute as a promising new antileukemic agent. Bryostatin 1 is found in Bugula neritina in poor yields (10^-4% dry weight). The focus of this research was to develop the biochemical and biosynthetic techniques that could be utilized to optimize the production of bryostatin 1 in Bugula neritina through aquaculture. To that end, the basic biosynthetic pathway to bryostatin 1 in the marine bryozoan was evaluated by using radiolabeled precursors. Techniques for the incorporation of these precursors were also developed. Other experiments involved an analysis of the composition of a specific population of Bugula neritina in terms of its bryostatin and lipid content. A determination of which lipids are produced de novo and which are exogenous was also undertaken.