. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 38 J. J. HANTEN AND S. K. PIERCE (kDa) CON CHX CAP 126- 90. Discussion LHCI, a family of plastid polypeptides essential for pho- tosynthesis, is synthesized while Vaucheria litorea chloro- plasts reside within the cells of the digestive diverticula of Elysia chlorotica. In addition, our data indicate the LHCI polypeptides are probably the products of genes located in the host-cell nuclear genome because their synthesis is inhibited by the cytosolic ribosome inhibitor, CHX, but not by the presence of the plastid ribosome
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 38 J. J. HANTEN AND S. K. PIERCE (kDa) CON CHX CAP 126- 90. Discussion LHCI, a family of plastid polypeptides essential for pho- tosynthesis, is synthesized while Vaucheria litorea chloro- plasts reside within the cells of the digestive diverticula of Elysia chlorotica. In addition, our data indicate the LHCI polypeptides are probably the products of genes located in the host-cell nuclear genome because their synthesis is inhibited by the cytosolic ribosome inhibitor, CHX, but not by the presence of the plastid ribosome inhibitor, CAP. This remarkable result would not be surprising in a plant or algal species since the LHCI polypeptide family's genes, Lhcal- Lhca6, reside in the nuclear DNA of all plants and algae examined to date (Jansson, 1994; Green and Durnford, (kDa) 126_ 90 B —. Figure 2. Autoradiograph of plastid proteins separated by SDS-PAGE gel run under the same conditions as those depicted in Figure 2. The plastid proteins incorporating [35S]-methionine label differ following treatment with CHX or CAP. The control (CON) represents chloroplast proteins isolated from slugs without inhibitor treatment. Arrows identify the ap- proximate positions of cyt/ (large arrow) and the LHCI (small arrows) proteins. CHX, CAP). As expected, the six polypeptide bands bound by the anti-LHCI in V. litomi and E. chlorotica plastids have a slightly greater size range—18 to 32 kDa—than those identified in P. cnicntiiin. These same antibody-la- beled bands from E. chlorotica plastid proteins incorporate radioactive label in the presence of CAP. but incorporation is blocked by the presence of CHX (Fig. 6). The amount of radiolabel precipitated by anti-LHCI from the slug plastid extracts following CHX treatment is only 2% of the control level, indicating a reduction in LHCI synthesis (Fig. 7). In contrast, the LHCI proteins in CAP- treated slugs incorporated [35S]-methionine at 92% of
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