Space Grant Consortium - University of Wisconsin - Green Bay

Abstract
New Initiatives in the Project on Fossilization via Silicification
Vera M. Kolb 1 and Patrick J. Liesch 2
1 Department of Chemistry
University of Wisconsin-Parkside
2 Department of Entomology
University of Wisconsin Madison
In t his pa per w e r eport o n o ur n ew in itiative in th e p roject o n f ossilization v ia
silicification. We focus on fossilization of insects and the role that chitin might have in
facilitating th e s ilicification. In th e i ntroduction w e of fer r ationalization f or t he
experiments. In the experimental section we report the initial results of the silicification
of insects, which were successful.
Introduction
In th e p ast w e h ave s tudied th e in teraction o f s odium s ilicate w ith various s mall
molecules, s uch as s ugars, a mino a cids, a lcohols, a nd ot hers. O ur recent review
summarizes our work, which was continuously sponsored by the Wisconsin Space Grant
Consortium (Kolb and Liesch, 2008). We became interested in the possible silicification
of insects via chitin, which is a polysaccharide they utilize extensively. This would be the
natural extension of our work on the silicates of sugars (Kolb and Zhu, 2004; Lambert et
al. 2004). Chitin is a long-chain polymer of N-acetylglucosamine in which the units are
linked via beta-1,4-linkage (Voet et al., 2006). Chitin is a constituent of the exoskeletons
of i nvertebrates s uch a s crustaceans a nd i nsects, and i s a lso f ound i n t he c ell w alls of
most f ungi and ma ny algae. C hemically, c hitin is s imilar to c ellulose in w hich o ne
hydroxyl group on each m onomer i s r eplaced by a n aminoacetyl f unction. C hitin is
seemingly ubiquitous in nature, and is almost as abundant as cellulose (Voet et al., 2006).
Chitin is a la bile mo lecule, b ut b ecomes r esistant to d ecay w hen c omplexed w ith
proteins. Such complexation occurs in arthropod cuticles, in which chitin is cross-linked
with pr oteins. S tankiewicz a nd B riggs (1997) ha ve s hown b y t he p yrolysis-gas
chromatography-mass s pectrometry (py-GC-MS) a nalysis t hat c hitin s urvived i n 25 -
million-year old fossilized insects. They have identified pyrolytic remnants of the chitin
and the associated protein. Flannery et al. (2001) have also shown that chitin can persist
under f avorable c onditions i n f ossils, a nd ha ve a dditionally i dentified t he g lucosamine
moiety b y G C-MS s elected i on m onitoring ( GC-MS-SIM). I nfra-red ( IR) s pectroscopy
was used by various investigators to observe and assign the chitin bands (Biniaś et al.,
2007; Briggs et al., 1998; Brugnerotto et al., 2001; Gow et al., 1987). This technique is
available t o us , a nd w e have s tudied t he IR s pectra o f s ilica gels th at were formed b y
silicification of va rious organic s amples ( Kolb a nd Liesch, 2008) . Thus, i nformation
exists for the IRs of both chitin and silicates.
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