Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 39

Full-Text Articles in Entire DC Network

Living On The Edge-Plants And Global Change In Continental And Maritime Antarctica, Sharon A. Robinson, J. Wasley, A. K. Tobin Dec 2003

Living On The Edge-Plants And Global Change In Continental And Maritime Antarctica, Sharon A. Robinson, J. Wasley, A. K. Tobin

Faculty of Science - Papers (Archive)

Antarctic terrestrial ecosystems experience some of the most extreme growth conditions on Earth and are characterised by extreme aridity and sub-zero temperatures. Antarctic vegetation is therefore at the physiological limits of survival and, as a consequence, even slight changes to growth conditions are likely to have a large impact, rendering Antarctic terrestrial communities sensitive to climate change. Climate change is predicted to affect the high latitude regions first and most severely. In recent decades, the Antarctic has undergone significant environmental change, including the largest increases in ultraviolet B (UV-B; 290-320nm) radiation levels in the world and, in the maritime region …


Extreme Marine Inundations (Tsunamis?) Of Coastal Western Australia, J. Nott, Edward A. Bryant Nov 2003

Extreme Marine Inundations (Tsunamis?) Of Coastal Western Australia, J. Nott, Edward A. Bryant

Faculty of Science - Papers (Archive)

Along 2500 km of the Western Australian coast, prehistoric ephemeral marine inundations (storm surges or tsunamis) were much larger than those that occurred since European settlement. The evidence is in the form of shell and coral deposits atop 30-m-high headlands, sand deposits containing large boulders, shell and coral several kilometers inland, and fields of large imbricated boulders across shore platforms. The size of transported boulders and the altitude of these deposits suggest that tsunamis were responsible, not large storm waves. The orientation of boulders reveals paleowave directions. Radiocarbon dating of the deposits suggest three very large tsunamis along this coast …


Poly(2-Alkylacrylic Acid) Polymers Deliver Molecules To The Cytosol By Ph-Sensitive Disruption Of Endosomal Vesicles, Rachel A. Jones, C. Y. Cheung, F. E. Black, J. K. Zia, P. S. Stayton, A. S. Hoffman, Mark R. Wilson May 2003

Poly(2-Alkylacrylic Acid) Polymers Deliver Molecules To The Cytosol By Ph-Sensitive Disruption Of Endosomal Vesicles, Rachel A. Jones, C. Y. Cheung, F. E. Black, J. K. Zia, P. S. Stayton, A. S. Hoffman, Mark R. Wilson

Faculty of Science - Papers (Archive)

The permeability barrier posed by cell membranes represents a challenge for the delivery of hydrophilic molecules into cells. We previously proposed that poly(2- alkylacrylic acid)s are endocytosed by cells into acidified vesicles and are there triggered by low pH to disrupt membranes and release the contents of endosomes/lysosomes to the cytosol. If this hypothesis is correct, these polymers could be valuable in drug delivery applications. This report provides functional comparisons of a family of three poly(2-alkylacrylic acid)s. Poly(2-propylacrylic acid) (PPAA), poly(2-ethylacrylic acid) (PEAA), and poly(2-methylacrylic acid) (PMAA) were compared in red blood cell haemolysis assays and in a lipoplex gene …


Novel Pharmacophore Based Methods Reveal Gossypol As A Reverse Transcriptase Inhibitor, Paul A. Keller, C. Birch, S. P. Leach, D. Tyssen, R. Griffith Mar 2003

Novel Pharmacophore Based Methods Reveal Gossypol As A Reverse Transcriptase Inhibitor, Paul A. Keller, C. Birch, S. P. Leach, D. Tyssen, R. Griffith

Faculty of Science - Papers (Archive)

In a program to identify new structural entities for the inhibition of the HIV-1 reverse transcriptase (RT) enzyme via database searching, a series of RT pharmacophores were developed. By utilising a novel filtering technique, the National Cancer Institute database of compounds was scanned producing 15 compounds to be screened for activity. A notable inclusion was a series of gossypol derivatives. The testing of a series of compounds revealed the parent compound gossypol to be an HIV-1 reverse transcriptase inhibitor. These results suggest that at least part of its anti-HIV activity is due to gossypol targeting the non-nucleoside inhibitor binding pocket …


A Case Study Of Sodium Reduction In Breakfast Cereals And The Impact Of The Pick The Tick Food Information Program In Australia, P. G. Williams, A. Mcmahon, R. Boustead Mar 2003

A Case Study Of Sodium Reduction In Breakfast Cereals And The Impact Of The Pick The Tick Food Information Program In Australia, P. G. Williams, A. Mcmahon, R. Boustead

Faculty of Health and Behavioural Sciences - Papers (Archive)

In 1997 one of Australia’s largest food companies undertook a program of salt reduction in 12 breakfast cereals. The National Heart Foundation’s Pick the Tick program criterion (<400mg>sodium/100g) was used as a target value where possible. Twelve products were reformulated, with reductions ranging from 85-469mg sodium per 100g and an average reduction of 40% (12-88%). As a result, 235 tonnes of salt were removed annually from the Australian food supply and five more products were able to carry the Tick logo. The impact of the Pick the Tick program in changing the food supply extends beyond those products that …


Trend To Better Nutrition On Australian Hospital Menus 1986-2001 And The Impact Of Cook-Chill Food Service Systems, A. Mcclelland, P. G. Williams Jan 2003

Trend To Better Nutrition On Australian Hospital Menus 1986-2001 And The Impact Of Cook-Chill Food Service Systems, A. Mcclelland, P. G. Williams

Faculty of Health and Behavioural Sciences - Papers (Archive)

Objective To assess trends in the nutritional quality of hospital menus and examine differences between menus used in hospitals with cook-chill or cook-fresh food services.

Design Standard patient menus were analysed against 28 criteria to assess nutritional standards and compared to results from similar studies in 1986 and 1993.

Setting Menus were collected from 80 hospitals in New South Wales, Australia, including 36 using cook-chill food service systems.

Statistical Analysis Chi-squared analysis was used to assess differences between the proportions of hospitals meeting the criteria in 2001 and 1993 and between different types of hospitals.

Results In 2001 compared to …


Evaluation Of A Tool For Rating Popular Diet Books, L. Williams, P. G. Williams Jan 2003

Evaluation Of A Tool For Rating Popular Diet Books, L. Williams, P. G. Williams

Faculty of Health and Behavioural Sciences - Papers (Archive)

Objective The aim of this study was to develop a questionnaire for use by nutrition professionals to enable evaluation of popular diet books.

Design A questionnaire was developed incorporating quantified criteria based on current authoritative nutrition guidelines. Twenty two questions were included, relating to nutritional adequacy, daily energy allowance, recommended rate of weight loss, flexibility and sustainability, physical activity advice, use of supplements, claims, author’s credentials, and scientific evidence. The questionnaire was used to rate 35 diets in 20 popular diet books sold in Australia in 2001, in order to test its practicality, validity and sensitivity. A computerised dietary analysis …


Nutrition And Related Claims Used On Packaged Australian Foods - Implications For Regulation, P. G. Williams, H. Yeatman, S. Zakrzewski, B. Aboozaid, S. Henshaw, K. Ingram, A. Rankine, S. Walcott, F. Ghani Jan 2003

Nutrition And Related Claims Used On Packaged Australian Foods - Implications For Regulation, P. G. Williams, H. Yeatman, S. Zakrzewski, B. Aboozaid, S. Henshaw, K. Ingram, A. Rankine, S. Walcott, F. Ghani

Faculty of Health and Behavioural Sciences - Papers (Archive)

The aim of this study was to describe the use of nutrition and related claims on packaged food for sale in Australia and measure the compliance of such claims with regulations governing their use. A survey was conducted of the labelling of 6662 products in 40 different food categories on sale in New South Wales in 2001. Levels of compliance were assessed by comparing the claims on the label and data in the nutrition information panel with requirements of the Foods Standards Code and the Code of Practice on Nutrient Claims. Half of the products (51.3%) carried some type of …


Sexism Is In The Eye Of The Beholder: Does The Advertising Standards Board Reflect "Community Standards"?, Sandra C. Jones Jan 2003

Sexism Is In The Eye Of The Beholder: Does The Advertising Standards Board Reflect "Community Standards"?, Sandra C. Jones

Faculty of Health and Behavioural Sciences - Papers (Archive)

This study examines the Advertising Standards Board’s response to complaints lodged against advertisements between 1999 and 2001 under sub-section 2.3 of the AANA Code (portrayal of sex/sexuality/nudity). Between 1999 and 2001, the ASB considered 419 complaints lodged by members of the general public under this subsection of the Code, of which only three were upheld. The decisions reported in the ASB’s Case Reports for these three years are examined by assessing three advertisements from each of these years (including the only one in each year against which a complaint was upheld). Inconsistencies in the application of this sub-section of the …


Are Current Social Marketing Campaigns Getting Through To Undergraduate University Students?, Sandra C. Jones Jan 2003

Are Current Social Marketing Campaigns Getting Through To Undergraduate University Students?, Sandra C. Jones

Faculty of Health and Behavioural Sciences - Papers (Archive)

In this study, we conduct a survey of health behaviours among undergraduate university students. The health behaviours include weight control, exercise, smoking, alcohol consumption, use of illicit drugs, and safe-sex practices. By comparing the results with national survey results, we test the hypothesis that university students – who have completed high school, with better than average grades – are more likely to exhibit healthy behaviours and avoid unhealthy or unsafe behaviours than the general population. Detailed information on the health behaviours of university students is not currently available (see Australia’s Health 2000, in which there are no reports of health …


Consumer Confusion: Parents Nutritional Perceptions Of Food Advertisements, Christina Hoang, Sandra C. Jones, Jennifer Thornton Jan 2003

Consumer Confusion: Parents Nutritional Perceptions Of Food Advertisements, Christina Hoang, Sandra C. Jones, Jennifer Thornton

Faculty of Health and Behavioural Sciences - Papers (Archive)

Due to the increasing prevalence of childhood obesity in society, this study was undertaken to determine if advertisers could potentially be misleading parents through the nutritional claims made in advertisements for popular children’s food products. Research was conducted to determine the sorts of nutritional messages parents received from four food advertisements. In total, 41 parents from an Australian university childcare centre participated in the study. The results revealed several major discrepancies whereby parents’ perceived unhealthy products to be healthy – indicating a degree of consumer confusion among parents.


Believability And Effectiveness Of Young Adult Safe-Drinking Messages, N. Breen, Sandra C. Jones Jan 2003

Believability And Effectiveness Of Young Adult Safe-Drinking Messages, N. Breen, Sandra C. Jones

Faculty of Health and Behavioural Sciences - Papers (Archive)

This study investigates eight safe-drinking messages, using appeals to the ‘self’ versus appeals about ‘others’, in combination with either a low or high physical threat, or a low or high social threat. The participants were18-25 year old second-year university marketing students. An experimental design was used for data collection, which involved 196 participants, with the groups comprised of participants with homogenous demographic characteristics and drinking behaviour. Analysis of variance (ANOVA) was used to test the believability and effectiveness of the messages. It was determined that messages about ‘others’ were perceived as more believable and effective than the corresponding appeals used …


Cooking Attenuates The Ability Of High-Amylose Meals To Reduce Plasma Insulin Concentrations In Rats, Marc A. Brown, Leonard H. Storlien, Ian L. Brown, J Higgins Jan 2003

Cooking Attenuates The Ability Of High-Amylose Meals To Reduce Plasma Insulin Concentrations In Rats, Marc A. Brown, Leonard H. Storlien, Ian L. Brown, J Higgins

Faculty of Health and Behavioural Sciences - Papers (Archive)

No abstract provided.


Recognising Facial Expression From Spatially And Temporally Modified Movements, Frank E. Pollick, Harold C. Hill, Andrew Calder, Helena Paterson Jan 2003

Recognising Facial Expression From Spatially And Temporally Modified Movements, Frank E. Pollick, Harold C. Hill, Andrew Calder, Helena Paterson

Faculty of Health and Behavioural Sciences - Papers (Archive)

We examined how the recognition of facial emotion was influenced by manipulation of both spatial and temporal properties of 3-D point-light displays of facial motion. We started with the measurement of 3-D position of multiple locations on the face during posed expressions of anger, happiness, sadness, and surprise, and then manipulated the spatial and temporal properties of the measurements to obtain new versions of the movements. In two experiments, we examined recognition of these original and modified facial expressions: in experiment 1, we manipulated the spatial properties of the facial movement, and in experiment 2 we manipulated the temporal properties. …


Linking The Structure And Perception Of 3-D Faces: Gender, Ethnicity And Expressive Posture, Guillaume Vignali, Harold C. Hill, Eric Vatikiotis-Bateson Jan 2003

Linking The Structure And Perception Of 3-D Faces: Gender, Ethnicity And Expressive Posture, Guillaume Vignali, Harold C. Hill, Eric Vatikiotis-Bateson

Faculty of Health and Behavioural Sciences - Papers (Archive)

A statistical study of human face shape is reported whose overall goal was to identify and characterise salient components of facial structure for human perception and communicative behaviour. A large database of 3-D faces has been constructed and analysed for differences in ethnicity, sex, and posture. For each of more than 300 faces varying in race/ethnicity (Japanese versus Caucasian) and sex, nine postures (smiling, producing vowels, etc) were recorded. Principal components analysis (PCA) and linear discriminant analysis (LDA) were used to reduce the dimensionality of the data and to provide simple, yet reliable reconstruction of any face from components corresponding …


The Influence Of Red Meat Intake Upon The Response To A Resistance Exercise-Training Program In Older Australians, Peter L. Mclennan, Linda C. Tapsell, Alice Owen, Irene Gutteridge Jan 2003

The Influence Of Red Meat Intake Upon The Response To A Resistance Exercise-Training Program In Older Australians, Peter L. Mclennan, Linda C. Tapsell, Alice Owen, Irene Gutteridge

Faculty of Health and Behavioural Sciences - Papers (Archive)

No abstract provided.


Psychology And The Enhancement Of Medication Adherence, Mitchell K. Byrne, Frank P. Deane Jan 2003

Psychology And The Enhancement Of Medication Adherence, Mitchell K. Byrne, Frank P. Deane

Faculty of Health and Behavioural Sciences - Papers (Archive)

This paper reports on a new approach to the enhancement of medication adherence - Medication Alliance. Medication Alliance was developed and piloted by a project team that includes Mitch Byrne as project leader, Frank Deane as research supervisor, and two consultants, Tim Coombs and Gordon Lambert. Because Medication Alliance borrows heavily from psychological principles such as functional analysis and cognitive therapy, this presentation is entitled 'Psychology and the Enhancement of Medication Adherence '. However, Medication Alliance is a non-discipline specific therapy approach that fits well within the purview of any clinician delivering psychosocial interventions. The theoretical underpinnings of the various …


Coherent Perspective Jitter Induces Visual Illusions Of Self-Motion, Stephen A. Palmisano, Darren Burke, Robert S Allison Jan 2003

Coherent Perspective Jitter Induces Visual Illusions Of Self-Motion, Stephen A. Palmisano, Darren Burke, Robert S Allison

Faculty of Health and Behavioural Sciences - Papers (Archive)

Previous research by Palmisano, Gillam and Blackburn (2000) found that adding coherent perspective jitter to constant velocity radial flow improved visually induced illusions of self-motion (known as vection). This was a surprising finding, because unlike pure radial flow, this jittering radial flow should have generated sustained visual-vestibular conflicts - previously thought to always reduce/impair vection. The current experiments attempted to ascertain the essential stimulus features for this jitter advantage for vection by examining three novel types of jitter display. While adding incoherent jitter to radial flow was found to impair vection, adding coherent non-perspective jitter had little effect on this …


Probing Dna Selectivity Of Ruthenium Metallointercalators Using Esi Mass Spectrometry, Jennifer L. Beck, Rajesh Gupta, Thitima Urathamakul, Nyree L. Williamson, Margaret Sheil, Janice Aldrich-Wright, Stephen F. Ralph Jan 2003

Probing Dna Selectivity Of Ruthenium Metallointercalators Using Esi Mass Spectrometry, Jennifer L. Beck, Rajesh Gupta, Thitima Urathamakul, Nyree L. Williamson, Margaret Sheil, Janice Aldrich-Wright, Stephen F. Ralph

Faculty of Science - Papers (Archive)

ESI mass spectra show that up to five ruthenium molecules can bind non-covalently to double stranded 16mer DNA, and provide information on the relative affinity and DNA sequence selectivity of different ruthenium complexes.


Evolution Of Chemical Contaminant And Toxicology Studies, Part 2- Case Studies Of Selenium And Arsenic, Glennys O'Brien, Dianne Jolley, Robert John Morrison Jan 2003

Evolution Of Chemical Contaminant And Toxicology Studies, Part 2- Case Studies Of Selenium And Arsenic, Glennys O'Brien, Dianne Jolley, Robert John Morrison

Faculty of Science - Papers (Archive)

As the second of a two part series discussing the evolution of the field of environmental toxicology, this paper presents two case studies: selenium and arsenic. Developments over several decades in the understanding of the behaviour of arsenic and selenium in different chemical forms in various compartments of the environment are discussed. Selenium was initially thought to be toxic, but later investigations showed it to be an essential micronutrient with a variety of biochemical functions, and, importantly, that there is a very narrow gap between the essential and the toxic body burden. Arsenic, on the other hand, has not yet …


Application Of Rusle For Erosion Management In A Coastal Catchment, Southern Nsw, A. D. Simms, C. D. Woodroffe, B. G. Jones Jan 2003

Application Of Rusle For Erosion Management In A Coastal Catchment, Southern Nsw, A. D. Simms, C. D. Woodroffe, B. G. Jones

Faculty of Science - Papers (Archive)

River catchments are dynamic and vulnerable systems that can change markedly when exposed to human impact. Changes induced since European settlement in Australia are of particular interest because impacts can be almost impossible to reverse. A measure of catchment degradation may be determined using accumulation in lakes. Along the east coast of New South Wales, both the rate of sediment infill and the stage of infill reached differ between coastal lagoons as a function of physical characteristics within their catchments, including the erosive power of rainfall, the intrinsic susceptibility of the soils to erosion, as well as the combined effect …


Asymmetric Synthesis Of (-)-7-Epiaustraline And (+)-1,7-Diepiaustraline, Minyan Tang, Stephen G. Pyne Jan 2003

Asymmetric Synthesis Of (-)-7-Epiaustraline And (+)-1,7-Diepiaustraline, Minyan Tang, Stephen G. Pyne

Faculty of Science - Papers (Archive)

A diastereoselective and modular approach to the synthesis of the 3-hydroxymethyl-2,3,5,6,7,7a-hexahydro-1H-pyrrolizine-1,2,7-triol structure, characteristic of several natural pyrrolizidine natural products has been developed. This approach culminated in the synthesis of (-)-7-epiaustraline and (+)-1,7-diepiaustraline. The oxazolidinone group has been found to be a useful protecting group in the RCM reaction and, as part of a pyrrolo[1,2-c]oxazol-3-one ring system, has functioned as a stereo- and regio-directing group, in a key diastereoselective cis-dihydroxylation reaction and a regioselective nucleophilic ring-opening of a S,S-dioxo-dioxathiole.


Chemo-Enzymatic Synthesis Of (-)-Epipentenomycin I, Tawesin Klomklao, Stephen G. Pyne, Apiwat Baramee, Brian W. Skelton, Allan H. White Jan 2003

Chemo-Enzymatic Synthesis Of (-)-Epipentenomycin I, Tawesin Klomklao, Stephen G. Pyne, Apiwat Baramee, Brian W. Skelton, Allan H. White

Faculty of Science - Papers (Archive)

A chemo-enzymatic synthesis of (−)-epipentenomycin I is reported using a lipase-catalysed kinetic resolution of the racemic pentacyclic alcohol 8. Flash vacuum pyroloysis of (−)-8 so obtained gave (−)-(4R)-4-hydroxy-5-methylene-2-cyclopentenone. Epoxidation of this compound with dimethyldioxirane followed by hydrolytic ring-opening of the resulting epoxide gave (−)-epipentenomycin I.


Photosynthesis In Silico: A Multimedia Cd-Rom Combining Animations, Simulations And Self-Paced Modules For Photosynthesis Education At All Tertiary Levels, Sharon A. Robinson, W. A. Russell, G. M.A. Netherwood Jan 2003

Photosynthesis In Silico: A Multimedia Cd-Rom Combining Animations, Simulations And Self-Paced Modules For Photosynthesis Education At All Tertiary Levels, Sharon A. Robinson, W. A. Russell, G. M.A. Netherwood

Faculty of Science - Papers (Archive)

Photosynthesis is a vital component of any undergraduate biology course. Despite its central importance in providing biochemical energy, fixed carbon and oxygen for all life on Earth, it remains an area which students find uninteresting and difficult to comprehend. This difficulty is compounded by problems with laboratory equipment for practical classes, which tends to be either expensive and complex, or simple and unreliable, making it extremely difficult to provide effective, hands-on teaching of photosynthesis to the large class sizes in undergraduate biology courses. A set of interactive, multimedia modules have been combined on a CD-ROM, which provides a new approach …


The Prevention Of Preterm Labour – Corticotropin Releasing Hormone Type 1 Receptors As A Target For Drug Design And Development, Paul A. Keller, K. Kirkwood, J. Morgan, S. Westcott, A. Mccluskey Jan 2003

The Prevention Of Preterm Labour – Corticotropin Releasing Hormone Type 1 Receptors As A Target For Drug Design And Development, Paul A. Keller, K. Kirkwood, J. Morgan, S. Westcott, A. Mccluskey

Faculty of Science - Papers (Archive)

The role of the corticotropin releasing hormone in the onset of labour and the subsequent medicinal chemistry implications of CRH antagonists for the prevention of premature birth, and identification of the CRH type 1 receptor as the target for this drug design, are reviewed here.


Modelling Tropical Cyclone Disturbance Of The Great Barrier Reef Using Gis, Marji Puotinen Jan 2003

Modelling Tropical Cyclone Disturbance Of The Great Barrier Reef Using Gis, Marji Puotinen

Faculty of Science - Papers (Archive)

Tropical cyclones periodically cross the Great Barrier Reef (GBR). Physical damage from the large waves they generate can significantly alter coral reef community structure over time. Yet cyclone disturbance of the GBR has not yet been examined for more than a few events and for only part of the region. Meteorological models can be used to hindcast the likely magnitude and distribution of cyclone energy from the Australian Bureau of Meteorology's tropical cyclone database. This hindcast energy, along with measures of the spatial patterning of reefs, can be linked statistically to field observations of reef impact to predict the distribution …


Changing Ecological Concerns In Rock-Art Subject Matter Of North Australia's Keep River Region, Paul Tacon, Ken Mulvaney, Sven Ouzman, Richard L. Fullagar, Lesley M. Head, Paddy Carlton Jan 2003

Changing Ecological Concerns In Rock-Art Subject Matter Of North Australia's Keep River Region, Paul Tacon, Ken Mulvaney, Sven Ouzman, Richard L. Fullagar, Lesley M. Head, Paddy Carlton

Faculty of Science - Papers (Archive)

The Keep River region has a complex body of engraved and painted rock-art, distinct from but with links to regions to the east, west and south. At least four major periods of figurative rock-art have been identified with differing subject matters and ages. Significant changes in depictions of human figures and animals are evident, reflecting shifts in emphasis associated with ecological concerns and environmental change. We flesh out the relative rock-art chronology by highlighting these changes, from worlds dominated by humans to those dominated by mammals and birds, and finally to a recent world of reptiles and humans. Symbolic aspects …


Development Of A Simple, Self-Consistent Polarizable Model For Liquid Water, Haibo Yu, Tomas Hansson, Wilfred Van Gunsteren Jan 2003

Development Of A Simple, Self-Consistent Polarizable Model For Liquid Water, Haibo Yu, Tomas Hansson, Wilfred Van Gunsteren

Faculty of Science - Papers (Archive)

The charge-on-spring method is used to develop a rigid, three-site, polarizable water model, a noniterative and a self-consistent version. In this method, the polarizability is taken into account by a variable separation of charges on selected polarizable centers. One of the pair of polarization charges resides on a polarizable center, while the other one is treated as an additional particle attached to the polarizable center by a parabolic restraint potential. The separation is calculated in response to the instantaneous electric field. We parametrized two models which are based on noniterative and self-consistent versions of the method, respectively. We computed several …


Tyrosine Phosphorylation Of Hsp-90 During Mammalian Sperm Capacitation, Heath W. Ecroyd, Russell C. Jones, Robert J. Aitken Jan 2003

Tyrosine Phosphorylation Of Hsp-90 During Mammalian Sperm Capacitation, Heath W. Ecroyd, Russell C. Jones, Robert J. Aitken

Faculty of Science - Papers (Archive)

The process of sperm capacitation is correlated with activation of a signal transduction pathway leading to protein tyrosine phosphorylation. Whereas phosphotyrosine expression is an essential prerequisite for fertilization, the proteins that are phosphorylated during capacitation have not yet been identified. In the present study, we observed that a major target of this signaling pathway is the molecular chaperone protein, heat shock protein (HSP)-86, a member of the HSP-90 family of HSPs. We used cross-immunoprecipitation experiments to confirm the tyrosine phosphorylation of HSP-86, a process that is not inhibited by the ansamycin antibiotic, geldanamycin. The general significance of these findings was …


Endogenous Redox Activity In Mouse Spermatozoa And Its Role In Regulating The Tyrosine Phosphorylation Events Associated With Sperm Capacitation, Heath W. Ecroyd, Russell C. Jones, Robert J. Aitken Jan 2003

Endogenous Redox Activity In Mouse Spermatozoa And Its Role In Regulating The Tyrosine Phosphorylation Events Associated With Sperm Capacitation, Heath W. Ecroyd, Russell C. Jones, Robert J. Aitken

Faculty of Science - Papers (Archive)

We investigated the role of endogenous redox activity in regulating the signal transduction pathway leading to tyrosine phosphorylation in mouse spermatozoa. Endogenous redox activity was monitored using a luminol-peroxidase chemiluminescent probe. Chemiluminescence increased in spermatozoa that were actively undergoing cAMP-mediated tyrosine phosphorylation events associated with capacitation and was inhibited in a dose-dependent manner by addition of catalase or diphenylene iodonium, both of which also inhibited tyrosine phosphorylation within the cell at points downstream of cAMP. Excluding bicarbonate from the incubation medium reduced the redox activity of sperm by 80-90% and dramatically reduced tyrosine phosphorylation. This study provides the first evidence …