title: Upgraded expression of 5S rRNA preludes the production of fibroin by spider glands.
abstract: We have developed the large ampullate glands of the orb-web spider Nephila clavipes as a model system in which to study the production of a tissue-specific secretory protein. Through simple manipulations, the glands' fibroin production can be practically abolished and subsequently elicited into high levels of synthesis through a mechanical stimulus applied to the organism. The tissue specific responses evoked by the stimulus can be monitored through time-course studies. The latter have revealed an orchestrated series of tissue and time specific macromolecular syntheses, which optimize the glandular tissues with components of the protein synthesis machinery. This work shows the upgraded accumulation of 5S rRNA in the glands as response to the stimulus within the earliest of the prelude events. Further enquiries on this accumulation must be conducted at the level of differential gene expressions, a chore we have initiated. A DNA fragment containing a single copy 5S rRNA gene has been isolated, cloned, sequenced, and transcribed in a cell-free system. We enclose a discussion on the similarity between the genomic organization of this gene to that of a 5S rRNA gene of Bombyx mori. Our studies have revealed a considerable number of similarities in the silk production strategies of Nephila clavipes and the silkworm Bombyx mori, some of them rather unusual.
authors.affiliation: University of Puerto Rico, San Juan, Puerto Rico 00931.
authors.forename: Edwin
authors.initials: E
authors.lastname: Vázquez
authors.forename: Gerado
authors.initials: G
authors.lastname: Arroyo
authors.forename: Iván J
authors.initials: IJ
authors.lastname: Cajigas
authors.forename: Graciela C
authors.initials: GC
authors.lastname: Candelas
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D005088:Exocrine Glands / Q000378:metabolism*; D005260:Female; D005349:Fibroins / Q000096:biosynthesis* / Q000378:metabolism; D005786:Gene Expression Regulation; D019476:Insect Proteins / Q000096:biosynthesis* / Q000378:metabolism; D012341:RNA, Ribosomal, 5S / Q000235:genetics* / Q000378:metabolism; D013112:Spiders / Q000235:genetics*
chemical_list: D019476:Insect Proteins; D012341:RNA, Ribosomal, 5S; D005349:Fibroins