S. Weisman, H. E. Trueman, S. T. Mudie, J. S. Church, T. D. Sutherland, V. S. Haritos

Spiders routinely produce multiple types of silk; however, common wisdom has held that insect species produce one type of silk each. This work reports that the green lacewing (Mallada signata, Neuroptera) produces two distinct classes of silk. We identified and sequenced the gene that encodes the major protein component of the larval lacewing cocoon silk and demonstrated that it is unrelated to the adult lacewing egg-stalk silk. The cocoon silk protein is 49 kDa in size and is alanine rich (>40%), and it contains an R-helical secondary structure. The final instar lacewing larvae spin protein fibers of ∼2 μm diameter to construct a loosely woven cocoon. In a second stage of cocoon construction, the insects lay down an inner wall of lipids that uses the fibers as a scaffold. We propose that the silk protein fibers provide the mechanical strength of the composite lacewing cocoon whereas the lipid layer provides a barrier to water loss during pupation.

M. Huson, D. Evans, J. Church, S. Hutchinson, J. Maxwell, G. Corino

Wool fibres have been treated to remove the covalently bound lipid and characterised using lipid analysis, wettability and scanning probe microscopy. A model substrate consisting of alternating stripes of hydrophobic (predominantly CH₃ terminated molecules) and hydrophilic (COOH terminated molecules) surfaces, micro-printed onto a gold-coated mica surface was assessed using the SPM techniques of adhesion, friction and phase imaging and showed that SPM can easily distinguish these surfaces. When KOH/methanol treated wool fibres were examined, SPM showed an increase in coefficient of friction and a decrease in adhesion as the lipid is removed. The increased friction is consistent with studies on the model surface and confirms the hypothesis that the lipid layer decreases the surface friction of fibres. The decreased adhesion is consistent with results in the literature on hair, but is at odds with the results on the model surface. The strong contrast shown between the methyl and carboxylic acid surfaces in the friction image of the micro-patterned surface, and the complete absence of any such contrast developing with time of treatment of the wool fibres strongly suggests that the surface lipid is not present as a discrete outer layer on the fibre. A new model is proposed in which the lipid is intimately associated with the surface proteins and allows for changes in lipid concentration at the surface in response to changes in environmental conditions.

J. S. Church, D. J. Evans

A spectroscopic investigation into the reaction of sodium tetrathionate with cysteine at pH 5 both at the boil and at room temperature has been carried out. The Raman and infrared spectra of the model compounds cysteine, cysteine-S-sulfonate, cysteine-S-thiosulfonate, sodium thiosulfate and sodium sulfite were also obtained and vibrations involving the sulfur atoms were analyzed in detail. These results were utilized in the interpretation of the spectra obtained from tetrathionate–cysteine reaction mixtures. The reaction supernatants were analyzed by high performance thin layer chromatography while the precipitates were analyzed gravimetrically. It was found that during the reaction, the thiol groups of cysteine are oxidised to give predominantly cysteine-S-sulfonate. Cystine was also detected but was determined gravimetrically to be a minor reaction product. No significant amounts of cysteine-S-thiosulfonate were detected. The reaction is accompanied by the formation of elemental sulfur and a small amount of sulfite. Major Reaction pathways are put forth that are consistent with the experimental data.

J. Y. Cai, D. J. Evans, J. S. Church

This paper reports a new application for amineboranes in the bleaching of wool, a typical example of keratin fibre. It has been found in this investigation that amineboranes are unique reductive bleaching agents that do not attack cystine disulphide bonds in wool keratin and do not impart permanent set to the fibre during bleaching. Selected amineborane compounds can be used in conjunction with oxidative agents such as hydrogen peroxide in aqueous media to further enhance the whitening effect and prevent disulphide bond disruption in keratins. The results of this study have suggested that the researched technology outperforms existing bleaching methods on a number of levels and may be an important step towards a new commercial bleaching technology.

S. B. Pyecroft, A-M. Pearse, R. Loh, K. Swift, K. Belov, N. Fox, E. Noonan, A. D. Hyatt, L. F. Wang, D. B. Boyle, J.S. Church, D. Middleton, R. J. Moore

In the mid 1990s an emerging disease characterised by the development of proliferative lesions around the face of Tasmanian devils (Sarcophilus harrisii) was observed. A multi-disciplinary approach was adopted to define the condition. Histopathological and transmission electron microscopic examination combined with immunohistochemistry help define Devil Facial Tumour Disease (DFTD) as a neoplastic condition of cells of neuroendocrine origin. Cytogenetic analysis of neoplastic tissue revealed it to be markedly different from normal devil tissue and having a consistent karyotype across all tumours examined. Combined with evidence for Major histocompatability (MHC) gene analysis there is significant evidence to confirm the tumour is a transmissible neoplasm.

J. S. Church, A. L. Woodhead

An investigation into the spectroscopic analysis of cotton waxes on Australian cottons was undertaken. The chemical composition of cotton wax is complex and contains a number of lipid classes. Infrared transmission spectroscopy coupled with principal component analysis was found to be capable of discriminating between solvent-extracted cotton waxes with differences in their alkyl functionality. Based on high-performance thin-layer chromatography (HPTLC) results, these differences were associated with an increase in levels of the alkane wax component. On the basis of these results, a photo-acoustic spectroscopic method was developed that could be used to distinguish raw cottons on the basis of these differences. This method was utilized to screen cottons from the Cotton Seed Distributors 2001 seed trial. A preliminary assessment of the scouring and dyeing properties of the various cottons, identified using the photo-acoustic method, was carried out. The results tended to confirm that cottons with increased alkyl functionality, most likely associated with alkane wax, were more difficult to remove and residual wax on the fiber acted as a barrier to dyestuff penetration, thus lowering color yield.

Y. S. Li, Y. Wang, J. S. Church, F. Garzena, Z. Zhang, D. An

Raman, and infrared spectra of mesna and dimesna have been collected in the present spectroscopic studies. Based on the group frequencies, relative intensities and Raman depolarization measurements, some vibrational assignments have been suggested. For both mesna and dimesna, at least two rotational conformers have been identified. Adsorption behavior was investigated from the recorded surface-enhanced Raman scattering (SERS) spectra. It was found that both mesna and dimesna adsorbed as thiolate on silver sol particles with the cleavage of the S-H bond in mesna and the S-S bond in dimesna. For the adsorbed thiolate, two conformers existed in the adsorption state.

F. Carrillo, X. Colom, J. Valldepras, D. Evans, M. Huson, J. S. Church

The mechanical, structural, and dyeing properties of solvent-spun lyocell fibers in a plain weave fabric are studied before and after industrial treatments of mechanical fibrillation and enzymatic defibrillation. Stress-strain relationships, surface morphology, crystallinity, and dye uptake are assessed for each of the samples and compared. Both treatments significantly decrease the tensile failure properties of the yarns. There are no appreciable changes in the Young's modulus, nor are there significant differences in yarn linear density or fiber diameter. Fourier transform infrared spectroscopy and x-ray diffraction results identify the crystalline morphology of the lyocell fibers as cellulose II. Spectroscopy results indicate that a small decrease in crystallinity takes place with industrial processing. The rate of decreased fiber crystallinity during ball milling is facilitated by the fibrillation and enzymatic treatments. Compared to the untreated fabric, both treated fabrics exhibit increased dye uptake rates, which appear to be greatest after fibrillation.