Characterization of the large diameter fibers in egg case silk : identification of a core fibroin, TuSp1, and localization of fibroin-like molecules, ECPs, from the black widow spider, latrodectus hesperus

<p>Araneoid spiders use specialized sets of abdominal silk glands to produce up to seven different types of silks, each with diverse functional properties. At the time of these studies, fibroin eDNA sequences that encode egg case silk had not been reported in the literature. This study used conventional nucleic acid-nucleic acid screening of a eDNA library to isolate a novel gene, named tubuliform spidroin 1 , from the black widow spider Latrodectus hesperus. TuSp 1 was demonstrated to be selectively expressed in the tubuliform gland (the gland suspected for egg case silk production), and examination of the amino acid sequence revealed highly homogeneous repeats (184 amino acid ensemble repeats), a characteristic feature of fibroin sequences. Analyses of the ensemble repeats within the amino acid sequence of TuSp 1 revealed the lack of long stretches of polyalanine and glycine-alanine sub-repeats, which are commonly found in minor ampullate and major ampullate silks. Polyserine blocks and short polyalanine stretches were highly represented in the TuSp 1 amino acid sequence. Our data support the assertion that TuSp 1 represents the main constituent within egg case silk. This supposition is supported by the observation that the amino acid composition of raw egg case silk was strikingly similar to the amino acid composition predicted from the translated TuSp1 eDNA. Two additional constituents identified in black widow egg case, egg case protein 1 (ECP-1) and egg case protein 2 (ECP-2), were also partially characterized in this study. Using immunohistochemical approaches, we demonstrate that ECPs predominantly localize to the exterior of the large diameter fibers of egg cases. Additionally, these studies revealed smaller amounts of ECPs localized to the interior portion of the fibers. Collectively, these results support TuSp1 as the predominant fibroin within egg sacs as well as reveal a structural role for the ECPs, providing clues regarding the supramolecular structure of egg case fibers.</p>

Name thesis:degree_name

Master of Science (M.S.)

Level thesis:degree_level

Thesis - Pacific Access Restricted

Discipline thesis:degree_discipline

Biological Sciences

Year dc:date.available

2008

Author dc:creator

• McMullen, Erin

Contributors dc:contributor

• Craig Vierra

• Black widow spider Genetics
• Spider webs
• Silk Composition Genetic aspects
• Genetic transcription
• Proteins Analysis
• Biology
• Life Sciences

Licence

• http://rightsstatements.org/vocab/InC/1.0/

Repository record dc:identifier

https://scholarlycommons.pacific.edu/uop_etds/704

OAI identifier oai:identifier

oai:scholarlycommons.pacific.edu:uop_etds-1703