7 research outputs found
Multiscale mechanisms of nutritionally induced property variation in spider silks
<div><p>Variability in spider major ampullate (MA) silk properties at different scales has proven difficult to determine and remains an obstacle to the development of synthetic fibers mimicking MA silk performance. A multitude of techniques may be used to measure multiscale aspects of silk properties. Here we fed five species of Araneoid spider solutions that either contained protein or were protein deprived and performed silk tensile tests, small and wide-angle X-ray scattering (SAXS/WAXS), amino acid composition analyses, and silk gene expression analyses, to resolve persistent questions about how nutrient deprivation induces variations in MA silk mechanical properties across scales. Our analyses found that the properties of each spider’s silk varied differently in response to variations in their protein intake. We found changes in the crystalline and non-crystalline nanostructures to play specific roles in inducing the property variations we found. Across treatment <i>MaSp</i> expression patterns differed in each of the five species. We found that in most species <i>MaSp</i> expression and amino acid composition variations did not conform with our predictions based on a traditional <i>MaSp</i> expression model. In general, changes to the silk’s alanine and proline compositions influenced the alignment of the proteins within the silk’s amorphous region, which influenced silk extensibility and toughness. Variations in structural alignment in the crystalline and non-crystalline regions influenced ultimate strength independent of genetic expression. Our study provides the deepest insights thus far into the mechanisms of how MA silk properties vary from gene expression to nanostructure formations to fiber mechanics. Such knowledge is imperative for promoting the production of synthetic silk fibers.</p></div
Comparisons of the expressions of the MaSp1 genes previously isolated from the <i>Argiope trifasciata</i> (MaSp1a) and <i>Latrodectus hesperus</i> (MaSp1b), and the MaSp2 genes from <i>Argiope trifasciata</i> (MaSp2a) and <i>Latrodectus hesperus</i> (MaSp2b), across treatments for each of the five spiders.
<p>Where P = protein fed and N = protein deprived treatments, <i>Ak</i> = Argiope <i>keyserlingi</i>, <i>Et</i> = <i>Eriophora transmarina</i>, <i>Lh</i> = <i>Latrodectus hasselti Np</i> = <i>Nephila plumipes</i>, <i>Pg</i> = <i>Phonognatha graeffei</i>.</p
Flow diagram of the methods implemented to examine the consequences of protein deprivation on MA silk gene expression, protein nanostructures, and mechanical properties for five species of spiders.
<p>Flow diagram of the methods implemented to examine the consequences of protein deprivation on MA silk gene expression, protein nanostructures, and mechanical properties for five species of spiders.</p
SAXS derived intensity <i>vs</i> waveband parameter (<i>q</i>) plots for the MA silks each of the 5 species’ MA silk.
<p>Where P = protein fed and N = protein deprived treatments, <i>Ak</i> = Argiope <i>keyserlingi</i>, <i>Et</i> = <i>Eriophora transmarina</i>, <i>Lh</i> = <i>Latrodectus hasselti Np</i> = <i>Nephila plumipes</i>, <i>Pg</i> = <i>Phonognatha graeffei</i>.</p
WAXS derived intensity <i>vs</i> 2<i>θ</i> plots for MA silks of each species.
<p>Where P = protein fed and N = protein deprived treatments, <i>Ak</i> = Argiope <i>keyserlingi</i>, <i>Et</i> = <i>Eriophora transmarina</i>, <i>Lh</i> = <i>Latrodectus hasselti Np</i> = <i>Nephila plumipes</i>, <i>Pg</i> = <i>Phonognatha graeffei</i>.</p
WAXS images derived for MA silks of each species of spider.
<p>Where P = protein fed and N = protein deprived treatments, <i>Ak</i> = Argiope <i>keyserlingi</i>, <i>Et</i> = <i>Eriophora transmarina</i>, <i>Lh</i> = <i>Latrodectus hasselti Np</i> = <i>Nephila plumipes</i>, <i>Pg</i> = <i>Phonognatha graeffei</i>.</p
Summary of the consequences of protein deprivation on silk properties for the five species examined.
<p>Summary of the consequences of protein deprivation on silk properties for the five species examined.</p