Small ampullate glands of Nephila clavipes

The small ampullate glands of the orb-web spider, Nephila clavipes, have be en studied and compared to other of the silk producing glands from this org anism. They exhibit the same gross morphological features of the other glan ds. Electrophoretic analyses show that the gland's luminal contents migrate as a single band, while the contents of the secretory epithelium reveal a step-ladder array of peptides in addition to the full size product. Previou s studies from our laboratory identified these peptides as products generat ed by translational pauses. This alternate mode of translation is typical o f fibroin synthesis in all the spider glands thus far studied as well as in those of the silkworm. The correlation of the peptides to the process of f ibroin synthesis is shown through experimental evidence in this paper. The gradual ultrastructural changes in Golgi vesicles elicited by the fibroin s ynthesis stimulus can be seen in this paper. The response to stimulation is of a higher magnitude in these glands than in any of those previously anal yzed. These studies show the small ampullate glands are a promising and cer tainly exploitable model system for studies on the synthesis of tissue-spec ific protein product and its control. (C) 2000 Wiley-Liss, Inc.