20th International Congress of Arachnology

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DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
individuals is also commonly used as a visual signal
in intraspecific communications in many species, but
evidence of whether it could be an appropriate proxy
of RHP is scarce. Here, we staged contests between
age- and size-matched male Siler semiglaucus, a
widely distributed Southeast Asian jumping spider, to
tackle this question in terms of its effect on both contest
outcome and strategy. Meanwhile, we investigated if
contest intensity (escalation) could also serve as a
measure of contest cost, compare with contest duration
in male-male contest.
Keywords: male-male contest, assessment strategy,
coloration, jumping spider, Siler semiglaucus
Oral presentation
Spider silk does not support the growth of
bacteria
Shichang Zhang, Yi-Ru Lee, Pi-Han Wang, Chen-Pan
Liao, I-Min Tso
Department of Life Science, Tunghai University,
Taichung 40704, Taiwan;
Spider silks are fascinating biopolymers, the strength of
which can be comparable to that of the synthetic super
fiber Kevlar. Their mechanical properties have been
intensively investigated, however, their chemical prop-
erties have received less attention. Though spider silks
are made from proteins, in nature they were seldom
observed to be decomposed by bacteria or fungi. To
reveal why microbes can not grow well on spider silk,
we tested silks of three spider species building three web
types: orb web builder Nephila pilipes (Nephilidae), the
funnel web builder Hippasa holmerae (Lycosidae), and
the tent web builder Cyrtophora moluccensis (Aranei-
dae). We used Bacillus subtilis, Escherichia coli, and
two strains of bacteria isolated from silk decoration of
Cyclosa mulmeinensis (Araneidae). We examined the
antimicrobial effect of spider silks by cross-streaking
assays and the results showed that there was no inhibi-
tion zone in the vicinity of spider silks. In addition, we
also used spider web silks to culture the bacteria using
three different media: LB (containing all nutrients),
NFG (nitrogen-free glucose) and PBS (no nutrient
buffer). Results showed that the number of bacteria in
LB medium was significantly higher than those in NFG
and PBS media. However, the number of bacteria cul-
tured in NFG and PBS media did not differ significantly.
These results suggest that the reason bacteria can not
easily consume spider silk is that the nutrients in spider
silk can not support the growth of bacteria, rather than
the silk containing antimicrobial chemicals to inhibit
the growth of bacteria.
Keywords: spider silk, bacterial growth, Nephila pilipes,
Hippasa holmerae, Cyrtophora moluccensis
Oral presentation
If they could only bite you: venom com-
position and potency of daddy long-leg
spider venom
Pamela A. Zobel-Thropp1, Jennifer Mullins 1, Charles
Kristensen2, Cynthia L. David3, Linda A. Breci3, Greta
Binford1
1Department of Biology, Lewis & Clark College,
Portland, OR 97219, USA; 2Spider Pharm, Yarnell,
AZ 86362, USA; 3Arizona Proteomics Consortium,
University of Arizona, Tucson, AZ 85721, USA
Pholcid or “daddy long-legs” spiders are notorious for
their toxic venom, even though its potency has never
formally been studied. Urban myths surrounding the
venom of these common spiders have survived years of
curiosity and rumor with no supporting scientific evi-
dence. We have identified the venome - transcriptomic
and proteomic venom components - of the North Ameri-
can species Physocyclus mexicanus and analyzed its
potency on natural prey. The result is a comprehensive
collection of data from Sanger sequencing, Illumina
3000 sequencing, and mass spectrometry (LC-MS/MS).
We found that the majority of the venom proteome are
toxic elements including digestive enzymes (astacin
metalloproteases, serine proteases and metalloendo-
peptidases) and venom peptide neurotoxins. We have
identified several new groups of venom peptides, all of
which are homologous with toxins from other haplogy-
nes (e<10-5), except one. Finally, bioassays on crickets
20th International Congress of Arachnology