ORCID Profile
0000-0002-7220-6062
Current Organisations
AgResearch Ltd
,
Plant and Food Research Lincoln
,
University of Canterbury
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Publisher: Wiley
Date: 18-10-2007
DOI: 10.1111/J.1751-1097.2007.00210.X
Abstract: The application of fluorescent whitening agents (FWAs) significantly accelerates the photoyellowing of wool and silk under exposure to the ultraviolet and visible components of sunlight <500 nm. The photochemistry involved in this process is poorly understood, particularly the role of photoproducts derived directly from the FWA itself. Hydroxylation was identified as the key initial mechanism of photodegradation leading to coloration of the solution in the irradiation of the stilbene-derived FWA 4,4'-bis(2-sulfostyryl)biphenyl (DSBP) in the presence of hydrogen peroxide (H2O2). Polyhydroxylated DSBP derivatives were implicated as critical intermediates in the formation of yellow photoproducts under these conditions. The formation of trace quantities of DSBP quinone derivatives subsequent to hydroxylation was identified as the key cause of DSBP photoyellowing. These results are the first successful characterization of yellow photoproducts resulting directly from irradiation of a stilbene-based FWA. Formation of these yellow stilbene-based FWA-derived photoproducts may occur on the surface of FWA-treated wool exposed to simulated sunlight, as previous work has shown that H2O2 is photogenerated when wet FWA-treated wool is exposed to light. These results therefore suggest that yellow FWA-derived photoproducts contribute to the accelerated photoyellowing of FWA-treated wool.
Publisher: American Chemical Society (ACS)
Date: 17-07-2013
DOI: 10.1021/JF401464R
Abstract: Low-molecular-weight organic molecules, such as coumarins and stilbenes, are used commercially as fluorescent whitening agents (FWAs) to mask photoyellowing and to brighten colors in fabrics. FWAs achieve this by radiating extra blue light, thus changing the hue and also adding to the brightness. However, organic FWAs can rapidly photodegrade in the presence of ultraviolet (UV) radiation, exacerbating the yellowing process through a reaction involving singlet oxygen species. Inorganic nanoparticles, on the other hand, can provide a similar brightening effect with the added advantage of photostability. We report a targeted approach in designing new inorganic silicon- and germanium-based nanoparticles, functionalized with hydrophilic (amine) surface terminations as novel inorganic FWAs. When applied on wool, by incorporation in a sol-gel Si matrix, the inorganic FWAs improved brightness properties, demonstrated enhanced photostability toward UV radiation, especially the germanium nanoparticles, and also generated considerably lower levels of reactive oxygen species compared to a commercial stilbene-based organic FWA, Uvitex NFW.
Publisher: Elsevier BV
Date: 11-2012
Abstract: The gastrointestinal microbiota plays an important role in maintaining host health by preventing the colonization of pathogens, fermenting dietary compounds, and maintaining normal mucosal immunity. Particularly in early life, the composition of the microbiota profoundly influences the development and maturation of the gastrointestinal tract (GIT) mucosa, which may affect health in later life. Therefore, strategies to manipulate the microbiota during infancy may prevent the development of some diseases later in adult life. Earlier research suggested that term fetuses are sterile and that the initial bacterial colonization of the newborn GIT occurs only after the baby transits through the birth canal. However, recent studies have demonstrated that the colonization and/or contact of the fetus with the maternal GIT microbiota may start in utero. After vaginal birth, the colonization of the neonate GIT continues through contact with maternal feces and vaginal bacteria, leading to a relatively simple microbial community that is influenced by feeding type (breast vs. formula feeding). Maternal GIT microbiota, vaginal microbiota, and breast milk composition are influenced by maternal diet. Alterations of the maternal GIT microbiota composition via supplementation with probiotics and prebiotics have been shown however, transfer of these benefits to the offspring remains to be demonstrated. This review focuses on the influence of maternal GIT microbiota during the pre- and postpartum periods on the colonization of the infant GIT. In particular, it examines the manipulation of the maternal GIT microbiota composition through the use of probiotics and/or prebiotics and subsequent consequences for the health of the offspring.
Publisher: Elsevier BV
Date: 02-2010
DOI: 10.1016/J.JPHOTOBIOL.2009.11.008
Abstract: Photo-oxidation of proteinaceous fibres correlates directly to lowered appearance retention and performance, with particular commercial significance for wool and human hair. We here outline the first detailed proteomic evaluation of differential photo-oxidation occurring in the cuticle and cortex of wool fibres. After exposure of whole wool to UVB irradiation, physical disruption techniques designed to minimise further oxidative modification were utilised to prepare enriched cuticle and cortex fractions. This was followed by comprehensive redox proteomic analyses of photo-oxidation via the location within the fibre components of modifications to aromatic residues. An oxidative classification system was developed and applied to provide further insight into differential photo-oxidation. These results were compared with coloration changes observed within the cuticular and cortical components of the fibre. In this study, although the cuticle was observed to have a higher level of baseline oxidation, the cortex exhibited significantly higher levels of photo-oxidation under UVB irradiation. These proteomic results were supported by the observation of significantly higher photoyellowing within the cortex than within the cuticle. It has been assumed that fibre photo-oxidation was predominantly confined to the wool cuticle, and that changes within the cuticle had the greatest effect on appearance retention. These results provide new insight into the contribution of the cortex to photo-induced discoloration of proteinaceous animal fibres.
Publisher: Springer Science and Business Media LLC
Date: 07-2006
DOI: 10.1039/B603030K
Abstract: Understanding the photodegradation of complex protein systems represents a significant goal in protein science. The photo-oxidation and resultant photoyellowing of wool in sunlight is a severe impediment to its marketability. However, although some photomodifications have been found in irradiated model amino acid systems, direct identification of the chromophoric photoproducts responsible for photoyellowing in irradiated wool itself has proved elusive. We here describe the direct characterisation and location of yellow chromophores and related photomodifications within the proteins of photoyellowed wool fabric, utilising a quasi-proteomic approach. In total, eight distinct photoproducts were characterised. Of these, five were derived from tryptophan namely hydroxytryptophan, N-formylkynurenine, kynurenine, residues consistent with the dehydration of kynurenine, and hydroxykynurenine, while three were derived from tyrosine namely dihydroxyphenylalanine, dityrosine, and a cross-linked residue consistent with a hydroxylated dityrosine residue. Fourteen modified peptide sequences were identified and the positions of modification for thirteen of these were located within the primary structure of known wool proteins. The nature of the photoproducts characterised offer valuable insight into the reaction pathways followed in the UV-induced photoyellowing of wool proteins.
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 04-2017
DOI: 10.1016/J.FOODCHEM.2016.10.041
Abstract: It has long been recognised that there are differences between human milk and infant formulas which lead to differences in health and nutrition for the neonate. In this study we examine and compare the peptide profile of human milk and an exemplar infant formula. The study identifies both similarities and differences in the endogenous and postdigestion peptide profiles of human milk and infant formula. This includes differences in the protein source of these peptides but also with the region within the protein producing the dominant proteins. Clustering of similar peptides around regions of high sequence identity and known bioactivity was also observed. Together the data may explain some of the functional differences between human milk and infant formula, while identifying some aspects of conserved function between bovine and human milks which contribute to the effectiveness of modern infant formula as a substitute for human milk.
Publisher: Wiley
Date: 20-11-2013
DOI: 10.1002/IJC.28393
Abstract: Patients with high-grade, serous epithelial ovarian carcinoma (HGSOC) are generally diagnosed with extensive peritoneal metastases, and exhibit 5-year survival rates <30%. A subset of these tumours, defined as "immunoreactive," overexpress mRNA encoding the T-cell-recruiting chemokine CXCL10 (10-kDa interferon gamma-induced protein C-X-C motif chemokine 10). Tumour-infiltrating CD4(+) CD8(+) T-cells are a well-documented, positive prognostic indicator for HGSOC patients paradoxically, however, patients diagnosed with HGSOC (overexpressing CXCL10 and therefore theorised to recruit T-cells) typically exhibit poor survival. Recently, an "antagonistic" CXCL10 variant was identified that inhibited leucocyte recruitment to inflamed liver in vivo (Casrouge et al., J Clin Invest 2011 :308-17). We hypothesised that "immunoreactive" HGSOC might also express antagonistic CXCL10, interfering with leucocyte recruitment and contributing to poor patient prognosis. CXCL10 expression was analysed in HGSOC tissues grouped according to pathology, grade and FIGO stage at diagnosis, and its localisation and association with T-cells established by immunohistochemical staining in tissue microarrays. CXCL10 expression was increased in a subset of serous epithelial tumour s les however, it did not correlate well with CD45-positive tumour infiltrate. Immunoprecipitation and de novo sequence analysis of CXCL10 identified the N-terminally cleaved, "antagonistic" variant of CXCL10 specifically in malignant tumours, and not in benign ovarian disease. The data demonstrate the presence of the antagonistic form of CXCL10 in HGSOC for the first time, and provide a partial explanation for reduced leucocyte infiltration observed in these tumours. We suggest that CXCL10 cleavage and subsequent antagonism of immune cell recruitment may be a feature of the "immunoreactive" HGSOC subtype, leading to early impairment of the immune response and subsequently worsening patient prognosis.
Publisher: SAGE Publications
Date: 04-2006
Abstract: This paper describes the identification of the yellow chromophore-containing residue kynurenine within photoyellowed wool. Photoyellowed Merino wool fabric was tryptically digested and the resultant peptides were separated by high-performance liquid chromatography. Peaks with absorbance at 400 nm were collected and analyzed by tandem quadrupole time-of-flight mass spec-trometry. Kynurenine was identified as a yellow chromophore in two peptide sequences characteristic of Type 1 intermediate filament and high glycine-tyrosine wool proteins. To our knowledge this is the first conclusive evidence confirming the identity of photoyellowed products and their location within the primary structure of wool proteins. A number of non-yellow modifications were identified in the course of this study and taken together with the identification of kynurenine modifications, these results support the current mechanistic theory of the radical oxidative process occurring during photoyellowing.
Publisher: Wiley
Date: 12-01-2007
Publisher: Wiley
Date: 17-06-2013
DOI: 10.1111/COTE.12039
Publisher: Wiley
Date: 03-2006
Publisher: Wiley
Date: 22-10-2009
DOI: 10.1111/J.1751-1097.2009.00614.X
Abstract: Fibrous proteins discolor on exposure to the UV component of sunlight. This effect is exacerbated in the presence of fluorescent whitening agents (FWAs), which are often applied to textiles to improve product brightness. Tryptophan photoproducts have been identified as significant contributors to protein photoyellowing however, the role of non-tryptophan-derived chromophores is less clear. In this study bovine collagen, containing no tryptophan residues, was irradiated in the presence and absence of the stilbene-derived FWA, 4,4'-bis(2-sulfostyryl)biphenyl (DSBP) and photoproducts were identified using mass spectrometry. Photoyellowing was found to be dependent on the presence of the FWA, attributed to lified generation of reactive oxygen species (ROS), particularly hydroxyl radicals and peroxynitrite. Four key proteinaceous photomodifications contributing directly to photoyellowing were located in irradiated collagen pretreated with DSBP, namely dopa, nitrophenylalanine, nitrotyrosine and nitrohistidine. This represents the first direct characterization of the three nitrated residues in the photoyellowing of an isolated fibrous protein, and implicates the ROS, peroxynitrite, as a key contributor to protein photoyellowing. Direct oxidative modification of the FWA itself was also observed. This study demonstrates that, even in the absence of tryptophan residues, significant photomodification of protein residues leading to chromophore formation occurs in the presence of an FWA.
Publisher: Wiley
Date: 09-10-2007
DOI: 10.1111/J.1600-0625.2007.00610.X
Abstract: The outermost protein layer of wool cuticle cells is known as the exocuticle a-layer. This layer is a resistant barrier to the degradation of the fibre and, as a result, little is known of its proteinaceous composition. Merino wool fibres were subjected to both proteolytic and chemical digestion and the resulting material was found by transmission electron microscopy to be highly enriched in a-layer. Amino acid analysis revealed a high cysteine and glycine content, with a close, but not exact, match to the Allwörden membrane. Subsequent digestion of the a-layer preparation by 2-nitro-5-thiocyano-benzoic acid produced a large number of short peptides, and analysis by mass spectrometry revealed peptides with strong homologies to cuticular ultra-high sulphur proteins of sheep wool and cuticular ultra-high and high-sulphur proteins of human hair, thus supporting other evidence for the presence of these sulphur-rich proteins in the a-layer.
No related grants have been discovered for Jolon Dyer.