Recent research on the eyes and vision-guided behaviour of jumping spiders (Salticidae) is review... more Recent research on the eyes and vision-guided behaviour of jumping spiders (Salticidae) is reviewed. Special attention is given to Portia Karsch. The species in this African, Asian and Australian genus have especially complex predatory strategies. Portia's preferred prey are other spiders, which are captured through behavioural sequences based on making aggressive-mimicry web signals, problem solving and planning. Recent research has
Portia fimbriata from Queensland, Australia, is a jumping spider (Salticidae) that preys on other... more Portia fimbriata from Queensland, Australia, is a jumping spider (Salticidae) that preys on other spiders, including other salticids. Cryptic stalking (palps retracted, walking very slowly and freezing when faced) is a prey- specific tactic deployed exclusively against salticid prey. Using vision alone, P. fimbriata discriminates salticid from non-salticid prey, with the prey salticid's large anterior median (AM) eyes providing critical
Portia fimbriata from Queensland, Australia, is an araneophagic jumping spider (Salticidae) that ... more Portia fimbriata from Queensland, Australia, is an araneophagic jumping spider (Salticidae) that includes in its predatory strategy a tactic (cryptic stalking) enabling it to prey effectively on a wide range of salticids from other genera. Optical cues used by P. fimbriata to identify the salticid species on which it most commonly preys, Jacksonoides queenslandicus, were investigated experimentally in the laboratory
Thermal treatment of meat proteins induces a range of observable and molecular-level changes. In ... more Thermal treatment of meat proteins induces a range of observable and molecular-level changes. In order to understand and track these heat-induced modifications at the amino acid level, various analytical techniques were used. Changes were observed both in the soluble and in the insoluble fractions after hydrothermal treatment of minced beef samples. Redox proteomics clearly indicated increasing oxidative modification of proteins with increased heat exposure. Collagens in the soluble fraction and myosin in the insoluble fraction were found to be highly susceptible to such modifications. Maillard reaction products in the insoluble and pyrrolidone formation in the soluble fraction steadily increased with increased heat exposure. Fluorescence studies indicated a rapid increase in fluorescence with heat, suggesting the formation of advanced glycation end products. Overall these results provide a deeper understanding of the effect of cooking on meat proteins and the possible relationship to processing conditions in meat-derived food.
Portia fimbriata from Queensland, Australia, is a jumping spider (Salticidae) that preys on other... more Portia fimbriata from Queensland, Australia, is a jumping spider (Salticidae) that preys on other spiders, including other salticids. Cryptic stalking (palps retracted, walking very slowly and freezing when faced) is a prey-specific tactic deployed exclusively against salticid prey. Using vision alone, P. fimbriata discriminates salticid from non-salticid prey, with the prey salticid's large anterior median (AM) eyes providing critical cues. Here, using computer-rendered virtual three-dimensional lures, we clarify experimentally some of the specific optical cues from AM eyes that influence the behaviour of P. fimbriata. Control lures were based on Jacksonoides queenslandicus, the salticid upon which P. fimbriata most commonly preys in nature. Experimental lures were modified to isolate specific combinations of AM eye features. For presentation to P. fimbriata, lures were projected on a small screen positioned in front of a web-covered platform. Each individual P. fimbriata was t...
Seasonal weight loss is the main limitation to animal production worldwide, significantly affecti... more Seasonal weight loss is the main limitation to animal production worldwide, significantly affecting the productivity of milk, meat and wool farms, particularly in drought-prone areas of the world where most of the large-scale wool production farms are located. Although the effect of nutritional status on wool quality parameters has been extensively studied, little is known on how it affects wool protein composition. Here, a proteomic approach has been applied to study changes in fiber structure and protein composition in wool from merino sheep subjected to experimentally induced weight loss. Results indicate that there is a significant reduction in the fiber diameter of wool from the animals on a restricted diet over a 42-day period. At the same time, significant increases in the expression of the high sulfur protein KAP13.1 and proteins from the high glycine-tyrosine protein KAP6 family in the wools from the animals on the restricted diet were also detected. Such findings have strong implications for the wool industry that favors finer wool. Seasonal weight loss caused by poor pasture availability has strong effects on wool productivity parameters and quality traits. In this work we determine that experimentally induced weight loss causes a decrease in fiber diameter associated with an increase in the level of high sulfur protein KAP13.1 and proteins from the high glycine-tyrosine protein KAP6 family. The implication of this is that decreasing the fiber diameter of the wool by this process could result in a fiber reduced prickle but with reduced wearability and appearance retention.
The presence of highly cross-linked protein networks in hair and wool makes them very difficult s... more The presence of highly cross-linked protein networks in hair and wool makes them very difficult substrates for protein extraction, a prerequisite for further protein analysis and characterization. It is therefore imperative that these cross-links formed by disulfide bridges are first disrupted for the efficient extraction of proteins. Chaotropes such as urea are commonly used as efficient extractants. However, a combination of urea and thiourea not only improves recovery of proteins but also results in improved resolution of the keratins in 2DE gels. Reductants also play an important role in protein dissolution. Dithiothreitol effectively removes keratinous material from the cortex, whereas phosphines, like Tris(2-carboxyethyl)phosphine, remove material from the exocuticle. The relative extractability of the keratins and keratin-associated proteins is also dependent on the concentration of chaotropes, reductants, and pH, thus providing a means to preferentially extract these proteins. Ionic liquids such as 1-butyl-3-methylimidazolium chloride (BMIM(+)[Cl](-)) are known to solubilize wool by disrupting noncovalent interactions, specifically intermolecular hydrogen bonds. BMIM(+)[Cl](-) proved to be an effective extractant of wool proteins and complementary in nature to chaotropes such as urea and thiourea for identifying unique peptides of wool proteins using mass spectrometry (MS). Successful identification of proteins resolved by one- or two-dimensional electrophoresis and MS is highly dependent on the optimal recovery of its protease-digested peptides with an efficient removal of interfering substances. The detergent sodium deoxycholate used in conjunction with Empore™ disks improved identification of proteins by mass spectrometry leading to higher percentage sequence coverage, identification of unique peptides and higher score.
Protein oxidative degradation is implicated in a wide range of deleterious effects. For human hai... more Protein oxidative degradation is implicated in a wide range of deleterious effects. For human hair, this oxidative damage can lead to significant observable changes in fiber physical and visual properties. A redox proteomic approach was applied to map molecular modification in human hair proteins and correlate this modification with the abundance of copper (II) ions, the levels of UV exposure and the general level of hair pigmentation. An increase in oxidative modification was observed with increasing copper (II) ion levels, regardless of the pigmentation level. Significantly, increased protein oxidative modification was also observed to occur in both lightly and darkly pigmented hair tresses even in the absence of irradiation, albeit at lower relative levels. Modification levels increased with increased copper (II) ion concentration. This new finding indicates that the level of copper (II) ions in human hair plays a key role in mediating protein oxidation, with or without exposure ...
Protein oxidative degradation is implicated in a wide range of deleterious effects. For human hai... more Protein oxidative degradation is implicated in a wide range of deleterious effects. For human hair, this oxidative damage can lead to significant observable changes in fiber physical and visual properties. A redox proteomic approach was applied to map molecular modification in human hair proteins and correlate this modification with the abundance of copper (II) ions, the levels of UV exposure and the general level of hair pigmentation. An increase in oxidative modification was observed with increasing copper (II) ion levels, regardless of the pigmentation level. Significantly, increased protein oxidative modification was also observed to occur in both lightly and darkly pigmented hair tresses even in the absence of irradiation, albeit at lower relative levels. Modification levels increased with increased copper (II) ion concentration. This new finding indicates that the level of copper (II) ions in human hair plays a key role in mediating protein oxidation, with or without exposure to UV light. Overall, these results strongly suggest that minimization of the level of copper (II) ions in human hair will mitigate and/or slow protein oxidative modification and therefore lower overall hair damage.
Novel Optical Systems Design and Optimization XIV, 2011
ABSTRACT We designed an optical system for tracking the retinal movement of a jumping spider as a... more ABSTRACT We designed an optical system for tracking the retinal movement of a jumping spider as a stimulus is presented to it. The system, using all off-the-shelf optical components except for one custom aspheric plate, consists of three sub-systems that share a common path: a visible stimuli presentation sub-system, a NIR illumination sub-system, and a NIR retinal imaging sub-system. A 25 mm clearance between the last element and the spider ensures a stable positioning of the spider. The stimuli presentation system relays an image from a display to the spider eye, matching the 15 arcmin resolution of the two principal eyes and producing a virtual image at a distance of 255 mm from the spider, with a visual full field of view of 52°. When viewing a stimulus, the spider moves its retinas, which cover a full field of view of only 0.6°, and directs them to view different places in the visual field. The retinal imaging system uses a NIR camera to track changes of 0.5° in the field of view seen by the spider. By tracking retinal movement across images presented to spiders, we will learn how they search for visual cues to identify prey, rivals, and potential mates.
Protein modification and damage in human hair, resulting from environmental, cosmetic and groomin... more Protein modification and damage in human hair, resulting from environmental, cosmetic and grooming stresses, create changes to visual and tactile characteristics and correlates with consumer perception of quality. This study outlines molecular-level evaluation of modification resulting from peroxide (bleaching) and alkaline straightening (relaxing) treatments. Redox proteomic profiling of virgin, bleached and relaxed hair tresses was performed, with comprehensive qualitative characterization of modification and semi-quantitative evaluation of damage through adaptation of a new damage scoring system. Modifications were mapped to specific locations in the hair proteome and a range of potential damage marker peptides identified. Virgin hair contained a baseline level of modification, consistent with environmental oxidative insult during hair growth. Hydrogen peroxide bleaching resulted in significantly increased levels of oxidative damage observable at the molecular level. This treatme...
Recent research on the eyes and vision-guided behaviour of jumping spiders (Salticidae) is review... more Recent research on the eyes and vision-guided behaviour of jumping spiders (Salticidae) is reviewed. Special attention is given to Portia Karsch. The species in this African, Asian and Australian genus have especially complex predatory strategies. Portia's preferred prey are other spiders, which are captured through behavioural sequences based on making aggressive-mimicry web signals, problem solving and planning. Recent research has
Portia fimbriata from Queensland, Australia, is a jumping spider (Salticidae) that preys on other... more Portia fimbriata from Queensland, Australia, is a jumping spider (Salticidae) that preys on other spiders, including other salticids. Cryptic stalking (palps retracted, walking very slowly and freezing when faced) is a prey- specific tactic deployed exclusively against salticid prey. Using vision alone, P. fimbriata discriminates salticid from non-salticid prey, with the prey salticid's large anterior median (AM) eyes providing critical
Portia fimbriata from Queensland, Australia, is an araneophagic jumping spider (Salticidae) that ... more Portia fimbriata from Queensland, Australia, is an araneophagic jumping spider (Salticidae) that includes in its predatory strategy a tactic (cryptic stalking) enabling it to prey effectively on a wide range of salticids from other genera. Optical cues used by P. fimbriata to identify the salticid species on which it most commonly preys, Jacksonoides queenslandicus, were investigated experimentally in the laboratory
Thermal treatment of meat proteins induces a range of observable and molecular-level changes. In ... more Thermal treatment of meat proteins induces a range of observable and molecular-level changes. In order to understand and track these heat-induced modifications at the amino acid level, various analytical techniques were used. Changes were observed both in the soluble and in the insoluble fractions after hydrothermal treatment of minced beef samples. Redox proteomics clearly indicated increasing oxidative modification of proteins with increased heat exposure. Collagens in the soluble fraction and myosin in the insoluble fraction were found to be highly susceptible to such modifications. Maillard reaction products in the insoluble and pyrrolidone formation in the soluble fraction steadily increased with increased heat exposure. Fluorescence studies indicated a rapid increase in fluorescence with heat, suggesting the formation of advanced glycation end products. Overall these results provide a deeper understanding of the effect of cooking on meat proteins and the possible relationship to processing conditions in meat-derived food.
Portia fimbriata from Queensland, Australia, is a jumping spider (Salticidae) that preys on other... more Portia fimbriata from Queensland, Australia, is a jumping spider (Salticidae) that preys on other spiders, including other salticids. Cryptic stalking (palps retracted, walking very slowly and freezing when faced) is a prey-specific tactic deployed exclusively against salticid prey. Using vision alone, P. fimbriata discriminates salticid from non-salticid prey, with the prey salticid's large anterior median (AM) eyes providing critical cues. Here, using computer-rendered virtual three-dimensional lures, we clarify experimentally some of the specific optical cues from AM eyes that influence the behaviour of P. fimbriata. Control lures were based on Jacksonoides queenslandicus, the salticid upon which P. fimbriata most commonly preys in nature. Experimental lures were modified to isolate specific combinations of AM eye features. For presentation to P. fimbriata, lures were projected on a small screen positioned in front of a web-covered platform. Each individual P. fimbriata was t...
Seasonal weight loss is the main limitation to animal production worldwide, significantly affecti... more Seasonal weight loss is the main limitation to animal production worldwide, significantly affecting the productivity of milk, meat and wool farms, particularly in drought-prone areas of the world where most of the large-scale wool production farms are located. Although the effect of nutritional status on wool quality parameters has been extensively studied, little is known on how it affects wool protein composition. Here, a proteomic approach has been applied to study changes in fiber structure and protein composition in wool from merino sheep subjected to experimentally induced weight loss. Results indicate that there is a significant reduction in the fiber diameter of wool from the animals on a restricted diet over a 42-day period. At the same time, significant increases in the expression of the high sulfur protein KAP13.1 and proteins from the high glycine-tyrosine protein KAP6 family in the wools from the animals on the restricted diet were also detected. Such findings have strong implications for the wool industry that favors finer wool. Seasonal weight loss caused by poor pasture availability has strong effects on wool productivity parameters and quality traits. In this work we determine that experimentally induced weight loss causes a decrease in fiber diameter associated with an increase in the level of high sulfur protein KAP13.1 and proteins from the high glycine-tyrosine protein KAP6 family. The implication of this is that decreasing the fiber diameter of the wool by this process could result in a fiber reduced prickle but with reduced wearability and appearance retention.
The presence of highly cross-linked protein networks in hair and wool makes them very difficult s... more The presence of highly cross-linked protein networks in hair and wool makes them very difficult substrates for protein extraction, a prerequisite for further protein analysis and characterization. It is therefore imperative that these cross-links formed by disulfide bridges are first disrupted for the efficient extraction of proteins. Chaotropes such as urea are commonly used as efficient extractants. However, a combination of urea and thiourea not only improves recovery of proteins but also results in improved resolution of the keratins in 2DE gels. Reductants also play an important role in protein dissolution. Dithiothreitol effectively removes keratinous material from the cortex, whereas phosphines, like Tris(2-carboxyethyl)phosphine, remove material from the exocuticle. The relative extractability of the keratins and keratin-associated proteins is also dependent on the concentration of chaotropes, reductants, and pH, thus providing a means to preferentially extract these proteins. Ionic liquids such as 1-butyl-3-methylimidazolium chloride (BMIM(+)[Cl](-)) are known to solubilize wool by disrupting noncovalent interactions, specifically intermolecular hydrogen bonds. BMIM(+)[Cl](-) proved to be an effective extractant of wool proteins and complementary in nature to chaotropes such as urea and thiourea for identifying unique peptides of wool proteins using mass spectrometry (MS). Successful identification of proteins resolved by one- or two-dimensional electrophoresis and MS is highly dependent on the optimal recovery of its protease-digested peptides with an efficient removal of interfering substances. The detergent sodium deoxycholate used in conjunction with Empore™ disks improved identification of proteins by mass spectrometry leading to higher percentage sequence coverage, identification of unique peptides and higher score.
Protein oxidative degradation is implicated in a wide range of deleterious effects. For human hai... more Protein oxidative degradation is implicated in a wide range of deleterious effects. For human hair, this oxidative damage can lead to significant observable changes in fiber physical and visual properties. A redox proteomic approach was applied to map molecular modification in human hair proteins and correlate this modification with the abundance of copper (II) ions, the levels of UV exposure and the general level of hair pigmentation. An increase in oxidative modification was observed with increasing copper (II) ion levels, regardless of the pigmentation level. Significantly, increased protein oxidative modification was also observed to occur in both lightly and darkly pigmented hair tresses even in the absence of irradiation, albeit at lower relative levels. Modification levels increased with increased copper (II) ion concentration. This new finding indicates that the level of copper (II) ions in human hair plays a key role in mediating protein oxidation, with or without exposure ...
Protein oxidative degradation is implicated in a wide range of deleterious effects. For human hai... more Protein oxidative degradation is implicated in a wide range of deleterious effects. For human hair, this oxidative damage can lead to significant observable changes in fiber physical and visual properties. A redox proteomic approach was applied to map molecular modification in human hair proteins and correlate this modification with the abundance of copper (II) ions, the levels of UV exposure and the general level of hair pigmentation. An increase in oxidative modification was observed with increasing copper (II) ion levels, regardless of the pigmentation level. Significantly, increased protein oxidative modification was also observed to occur in both lightly and darkly pigmented hair tresses even in the absence of irradiation, albeit at lower relative levels. Modification levels increased with increased copper (II) ion concentration. This new finding indicates that the level of copper (II) ions in human hair plays a key role in mediating protein oxidation, with or without exposure to UV light. Overall, these results strongly suggest that minimization of the level of copper (II) ions in human hair will mitigate and/or slow protein oxidative modification and therefore lower overall hair damage.
Novel Optical Systems Design and Optimization XIV, 2011
ABSTRACT We designed an optical system for tracking the retinal movement of a jumping spider as a... more ABSTRACT We designed an optical system for tracking the retinal movement of a jumping spider as a stimulus is presented to it. The system, using all off-the-shelf optical components except for one custom aspheric plate, consists of three sub-systems that share a common path: a visible stimuli presentation sub-system, a NIR illumination sub-system, and a NIR retinal imaging sub-system. A 25 mm clearance between the last element and the spider ensures a stable positioning of the spider. The stimuli presentation system relays an image from a display to the spider eye, matching the 15 arcmin resolution of the two principal eyes and producing a virtual image at a distance of 255 mm from the spider, with a visual full field of view of 52°. When viewing a stimulus, the spider moves its retinas, which cover a full field of view of only 0.6°, and directs them to view different places in the visual field. The retinal imaging system uses a NIR camera to track changes of 0.5° in the field of view seen by the spider. By tracking retinal movement across images presented to spiders, we will learn how they search for visual cues to identify prey, rivals, and potential mates.
Protein modification and damage in human hair, resulting from environmental, cosmetic and groomin... more Protein modification and damage in human hair, resulting from environmental, cosmetic and grooming stresses, create changes to visual and tactile characteristics and correlates with consumer perception of quality. This study outlines molecular-level evaluation of modification resulting from peroxide (bleaching) and alkaline straightening (relaxing) treatments. Redox proteomic profiling of virgin, bleached and relaxed hair tresses was performed, with comprehensive qualitative characterization of modification and semi-quantitative evaluation of damage through adaptation of a new damage scoring system. Modifications were mapped to specific locations in the hair proteome and a range of potential damage marker peptides identified. Virgin hair contained a baseline level of modification, consistent with environmental oxidative insult during hair growth. Hydrogen peroxide bleaching resulted in significantly increased levels of oxidative damage observable at the molecular level. This treatme...
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