The long range aim of the project is to analyze the synthesis of a tissue- specific product using a suitable and fruitful model system. The immediate aim of this proposal is to investigate the timely tissue-specific accumulation of U1 small nuclear RNA (U1 snRNA) elicited by the stimulation into protein synthesis of fibroin producing glands (the model system). U1 snRNA plays a vital role in protein synthesis in the maturating messenger RNA. The reasons for these studies arises from evidence accrued thus far on the macromolecular syntheses which precede that of the secretory protein itself. Within these events, increased U1 snRNA accumulation occurs prior to the synthesis of mRNA. This accumulation, basis for the proposed project, is the result of an increase in the expression of the gene coding for U1 snRNA. Thus the study will be directed at the gene and its transcriptional activity. Isolation, cloning and characterization of the genes will lead to studies on transcription under cell-free conditions. Once the cell-free system is optimized, the testing of both cls and trans acting can be properly questioned, studies that will contribute towards the elucidation of the mechanism(s) underlying the event under analysis. The timeliness of this event is the fact that its production precedes that of its target, mRNA. U1 snRNA is a highly conserved molecule, thus information from our studies may be applicable to other forms of life, including humans. The relevance of the work lies in the conserved nature of U1 snRNA, the ubiquitousness of protein synthesis, and the role of U1 in the maturation of mRNA. Conservation is a high point of these molecules and its associated proteins (RNPs). Fungal snRNAs are bound specifically by Xenopus snRNP proteins. Epitopes recognized by several of the autoimmune antisera from lupus erythematosus patients have been conserved on snRNP proteins from humans to fungus.