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Intranasal Vaccination With Streptococcal Fibronectin Binding Protein Sfb1 Fails To Prevent Growth And Dissemination Of Streptococcus Pyogenes In A Murine Skin Infection Model, Jason D. Mcarthur, E. Medina, J. Chin, B. J. Currie, K. S. Sriprakash, S. R. Talay, G. S. Chhatwal, Mark J. Walker Dec 2004

Intranasal Vaccination With Streptococcal Fibronectin Binding Protein Sfb1 Fails To Prevent Growth And Dissemination Of Streptococcus Pyogenes In A Murine Skin Infection Model, Jason D. Mcarthur, E. Medina, J. Chin, B. J. Currie, K. S. Sriprakash, S. R. Talay, G. S. Chhatwal, Mark J. Walker

Faculty of Science - Papers (Archive)

Fibronectin binding protein F1 (Sfb1) of Streptococcus pyogenes (group A streptococcus [GAS]) is a well-characterized adhesin that has been shown to induce protection in mice against a lethal intranasal GAS challenge after intranasal immunization with cholera toxin B subunit (CTB) as adjuvant. With a murine skin infection model, we have shown that Sfb1/CTB vaccination neither elicits opsonizing antibodies nor prevents systemic bacterial growth and dissemination to internal organs after a subcutaneous GAS challenge. These results indicate that an Sfb1-based vaccine should be complemented with additional protective antigens in order to be used in areas such as the tropical north ...


Two Distinct Genotypes Of Prtf2, Encoding A Fibronectin Binding Protein, And The Evolution Of The Gene Family In Streptococcus Pyogenes, V. Ramachandran, Jason D. Mcarthur, C. E. Behm, C. Gutzeit, M. Dowton, P. K. Fagan, R. Towers, B. J. Currie, K. S. Sriprakash, Mark J. Walker Nov 2004

Two Distinct Genotypes Of Prtf2, Encoding A Fibronectin Binding Protein, And The Evolution Of The Gene Family In Streptococcus Pyogenes, V. Ramachandran, Jason D. Mcarthur, C. E. Behm, C. Gutzeit, M. Dowton, P. K. Fagan, R. Towers, B. J. Currie, K. S. Sriprakash, Mark J. Walker

Faculty of Science - Papers (Archive)

The group A Streptococcus (GAS) is an important pathogen responsible for a wide range of human diseases. Fibronectin binding proteins (FBPs) play important role in promoting GAS adherence and invasion of host cells. The gene prtF2 encodes a FBP and is contained in approximately 60% of GAS strains. In the present study we have examined 51 prtF2-positive GAS strains isolated from the Northern Territory of Australia and describe two genotypes of prtF2, which are mutually exclusive. Both genotypes have been previously identified in the literature as pfbp and fbaB. We show these genotypes map to the same chromosomal location within ...


Austrochlamys Heardensis (Fleming, 1957) (Bivalvia: Pectinidae) From Central Kerguelen Plateau, Indian Ocean: Palaeontology And Possible Tectonic Significance, P. G. Quilty, C. V. Murray-Wallace, J. M. Whitehead Sep 2004

Austrochlamys Heardensis (Fleming, 1957) (Bivalvia: Pectinidae) From Central Kerguelen Plateau, Indian Ocean: Palaeontology And Possible Tectonic Significance, P. G. Quilty, C. V. Murray-Wallace, J. M. Whitehead

Faculty of Science - Papers (Archive)

Austrochlamys heardensis (Fleming) is recorded from a boulder of Late Pliocene (3.62–2.5 Ma) volcaniclastic sandstone dredged 70 km east-north-east of Heard Island, the third record of the species. The collection is much larger than the original described by Fleming and includes left valves which are described for the first time. The species is compared with A. anderssoni (Hennig) from Cockburn Island and ‘Chlamys’ mawsoni Fletcher from Îles Kerguelen. The source rock accumulated in fully marine, highly current-affected conditions. The collection is dominated by right valves, possibly because left valves are more susceptible to breakage and the effects ...


Australian Backyard Gardens And The Journey Of Migration, Lesley M. Head, Pat Muir, E. Hampel Jul 2004

Australian Backyard Gardens And The Journey Of Migration, Lesley M. Head, Pat Muir, E. Hampel

Faculty of Science - Papers (Archive)

Gardens have been an important site of environmental engagement in Australia since the British colonization. They are places where immigrant people and plants carry on traditions from their homelands, and work out an accommodation with new social and biophysical environments. We examine the backyard gardens of three contemporary migrant groups in suburban Australia, Macedonian, Vietnamese and British-born, and a fourth group of first generation Australians with both parents born overseas. There is strong emphasis on the production of vegetables in Macedonian backyards, and herbs and fruit in Vietnamese backyards. British backyards were more diverse, some focusing on non-native ornamental flowers ...


Comparison Of Solvent Regimes For The Extraction Of Photosynthetic Pigments From Leaves Of Higher Plants, J. L. Dunn, J. D. Turnbull, Sharon A. Robinson Apr 2004

Comparison Of Solvent Regimes For The Extraction Of Photosynthetic Pigments From Leaves Of Higher Plants, J. L. Dunn, J. D. Turnbull, Sharon A. Robinson

Faculty of Science - Papers (Archive)

The relative efficiency of methanol- and acetone-based solvents for the extraction of pigments from photosynthetic tissues of plant was compared, together with the advantages of multiple versus single extractions. The two commonly employed triple acetone extractions (100:80:80% and 85:100:100%) performed comparably for most pigments and for all plant species tested. Single extractions with either 96% methanol or 85% acetone failed to extract the more hydrophobic pigments, especially ?-carotene. We conclude that multiple extractions that combine pure and aqueous (80–85%) acetone are preferable for extraction of the full range of pigments. These results suggest that previous ...


Nativeness, Invasiveness And Nation In Australian Plants, Lesley M. Head, Pat Muir Apr 2004

Nativeness, Invasiveness And Nation In Australian Plants, Lesley M. Head, Pat Muir

Faculty of Science - Papers (Archive)

The conceptualization of alien invasive species conflates two axes of variability that have become unhelpfully blurred. The nativeness/alienness axis refers to the presumed belonging of a species in ecological or social space. Invasiveness refers to the behavior of the species in question, particularly in relation to other species. The overlay of nation introduces further variability. Teasing these axes apart is important for more effective environmental management. We examine these concepts using two influential forms of ecological knowledge: the biogeographical and ecological literature and the vernacular experiences of suburban backyarders. Three case studes, the invasive native Pittosporum undulatum and two ...


National Inquiry On Bushfire Mitigation And Management, S. Ellis, P. Kanowski, R. J. Whelan Mar 2004

National Inquiry On Bushfire Mitigation And Management, S. Ellis, P. Kanowski, R. J. Whelan

Faculty of Science - Papers (Archive)

Bushfires are an inherent part of the Australian environment. We cannot prevent them, but we can minimise the risks they pose to life, property and infrastructure, production systems, and the environment. Australia has a large and very capable force of volunteer and career firefighters, advanced firefighting technologies, and significant firefighting resources. But the geographical scale of our country, the large and expanding rural–urban interface, and the potential for rapid bushfire development and spread under adverse weather conditions mean that individual Australians cannot rely solely on fire agencies to protect their lives and property from bushfires. Bushfires have a fundamental ...


Trace Gas Emissions From Biomass Burning Inferred From Aerosol Optical Depth, Clare Paton-Walsh, N. B. Jones, Stephen R. Wilson, A. Meier, N. Deutscher, D. W. Griffith, R. Mitchell, S. Campbell Mar 2004

Trace Gas Emissions From Biomass Burning Inferred From Aerosol Optical Depth, Clare Paton-Walsh, N. B. Jones, Stephen R. Wilson, A. Meier, N. Deutscher, D. W. Griffith, R. Mitchell, S. Campbell

Faculty of Science - Papers (Archive)

We have observed strong correlations between simultaneous and co-located measurements of aerosol optical depth and column amounts of carbon monoxide, hydrogen cyanide, formaldehyde and ammonia in bushfire smoke plumes over SE Australia during the Austral summers of 2001/2002 and 2002/2003. We show how satellite-derived aerosol optical depth maps may be used in conjunction with these correlations to determine the total amounts of these gases present in a fire-affected region. This provides the basis of a method for estimating total emissions of trace gases from biomass burning episodes using visible radiances measured by satellite.


Protecting Group Effects On The Efficiency Of The Ruthenium-Catalyzed Alder-Ene Reaction, Joseph Hartley, Stephen G. Pyne Jan 2004

Protecting Group Effects On The Efficiency Of The Ruthenium-Catalyzed Alder-Ene Reaction, Joseph Hartley, Stephen G. Pyne

Faculty of Science - Papers (Archive)

The efficiency of the ruthenium-catalysed Alder-ene reaction of hydroxy alkenes depends heavily on the nature of the O-protecting groups employed as well as the length of the carbon spacer between the hydroxy and alkene group.


Negotiating Nature: Collaboration And Conflict Between Aboriginal And Conservation Interests In New South Wales, Australia, Michael Adams Jan 2004

Negotiating Nature: Collaboration And Conflict Between Aboriginal And Conservation Interests In New South Wales, Australia, Michael Adams

Faculty of Science - Papers (Archive)

Faced with the paradox of a large global increase in conservation reserves and a simultaneous global decrease in actual effective protection for biodiversity, conservation scientists and policymakers are questioning established conservation theory and practice. I argue that the fundamental premises, the foundational myths, for Western-style conservation also need to be questioned. The statistics on Indigenous land claims, and conservation reserves, in Australia and more specifically the state of New South Wales (NSW), reveal a landscape of policy failure in both arenas. Focusing on Australia, I use spatial analysis and policy histories to demonstrate converging trajectories of land use priorities for ...


Molecular Dynamics Simulations Of Peptides Containing An Unnatural Amino Acid: Dimerization, Folding, And Protein Binding, Haibo Yu, Xavier Daura, Wilfred Van Gunsteren Jan 2004

Molecular Dynamics Simulations Of Peptides Containing An Unnatural Amino Acid: Dimerization, Folding, And Protein Binding, Haibo Yu, Xavier Daura, Wilfred Van Gunsteren

Faculty of Science - Papers (Archive)

We have performed molecular dynamics (MD) simulations to study the dimerization, folding, and binding to a protein of peptides containing an unnatural amino acid. NMR studies have shown that the substitution of one residue in a tripeptide β-strand by the unnatural amino acid Hao (5-HO2CCONH-2-MeO-C6H3-CO-NHNH2) modifies the conformational flexibility of the β-strand and the hydrogen-bonding properties of its two edges: The number of hydrogen-bond donors and acceptors increases at one edge, whereas at the other, they are sterically hindered. In simulations in chloroform, the Hao-containing peptide 9 (i-PrCO-Phe-Hao-Val-NHBu) forms a β-sheet–like hydrogen-bonded dimer, in good agreement with the available ...


On The Transferability Of The Spcal Water Model To Biomolecular Simulation, Alice Glaettli, Chris Oostenbrink, Xavier Daura, Daan Geerke, Haibo Yu, Wilfred Van Gunsteren Jan 2004

On The Transferability Of The Spcal Water Model To Biomolecular Simulation, Alice Glaettli, Chris Oostenbrink, Xavier Daura, Daan Geerke, Haibo Yu, Wilfred Van Gunsteren

Faculty of Science - Papers (Archive)

We investigated the performance of the recently developed SPC/L model for liquid water, as a pure liquid, in binary mixtures with DMSO, and as a solvent model in a peptide folding simulation. Additionally, in order to test the compatibility with the GROMOS biomolecular force field, free energies of hydration of a set of representative compounds were computed. The results are compared to those for the well established SPC water model, which is generally used as a solvent model in conjunction with the GROMOS force field already for more than two decades. It turns out that as a pure liquid ...


Photosynthesis In Silico. Overcoming The Challenges Of Photosynthesis Education Using A Multimedia Cd-Rom, A. W. Russell, G. M.A. Netherwood, Sharon A. Robinson Jan 2004

Photosynthesis In Silico. Overcoming The Challenges Of Photosynthesis Education Using A Multimedia Cd-Rom, A. W. Russell, G. M.A. Netherwood, Sharon A. Robinson

Faculty of Science - Papers (Archive)

Photosynthesis is a central topic in biology education. It remains one of the most challenging, largely because of a) its conceptual difficulty, leading to lack of interest and misconceptions among students; b) the difficulties students have in visualising the process, or relating it to things they can see, especially when the topic is presented purely as a molecular process; and c) limitations to the practical demonstration of photosynthesis because equipment is either cheap, unreliable and antiquated or prohibitively expensive. In response, we have combined expertise in photosynthesis research and education, and in graphic design, to produce an interactive, multimedia package ...


Landscape Management: Is It The Future?, R. J. Whelan Jan 2004

Landscape Management: Is It The Future?, R. J. Whelan

Faculty of Science - Papers (Archive)

As a Keynote Address at the 2004 Nature Conservation Council Conference, Bushfire in a Changing Environment - New Directions in Management, this paper argues that the landscape is a template with biodiversity assets, and human assets and bushfires overlaid. Two case studies, the Greater Glider and Eastern Bristlebird, are used to illustrate how the impact of bushfire on a species is contingent on it is distributed in the landscape, relative to the locations of its remnant habitat. Mitigation of bushfire effects, using fuel-reduction programs, is a process that also needs to be considered at a landscape scale, and has the potential ...


Processes Controlling Metal Transport And Retention As Metal-Contaminated Groundwaters Efflux Through Estuarine Sediments, Stuart L. Simpson, Edward J. Maher, Dianne F. Jolley Jan 2004

Processes Controlling Metal Transport And Retention As Metal-Contaminated Groundwaters Efflux Through Estuarine Sediments, Stuart L. Simpson, Edward J. Maher, Dianne F. Jolley

Faculty of Science - Papers (Archive)

Factors affecting the transport and retention of Cd, Cr, Cu, Ni, Pb and Zn in acidic groundwaters as they pass through estuarine sediments were investigated using column experiments. Acidic groundwaters caused the rapid dissolution of iron sulfide (AVS) and other iron and manganese phases from sediments that are important for metal binding and buffering. Metal breakthrough to overlying water occurred in the order of Ni>Zn>Cd>>Cu>>Cr/Pb. Metal transport increased as the sediment permeability increased, reflecting the low resistance to flow caused by larger sand-sized particles and the decreased abundance of metal adsorption sites on these materials ...


Synthesis Of (+)-(1r,2s,9s,9ar)-Octahydro-1h-Pyrrolo-[1,2-A]Azepine-1,2,9-Triol: A Potential Glycosidase Inhibitor, Karl B. Lindsay, Stephen G. Pyne Jan 2004

Synthesis Of (+)-(1r,2s,9s,9ar)-Octahydro-1h-Pyrrolo-[1,2-A]Azepine-1,2,9-Triol: A Potential Glycosidase Inhibitor, Karl B. Lindsay, Stephen G. Pyne

Faculty of Science - Papers (Archive)

The title compound was prepared as a potential glycosidase inhibitor. Key steps in the synthesis are vinyl epoxide aminolysis, ring-closing metathesis, cis-dihydroxylation and then ring closure.


Phytochemical And Larvicidal Studies On Stemona Curtisii: Structure Of A New Pyriodo[1,2-A]Azepine Stemona Alkaloid, Pitchaya Mungkornasawakul, Stephen G. Pyne, Araya Jatisatienr, Damrat Supyen, Chaiwat Jatisatienr, Wilford Lie, Alison T. Ung, Brian W. Skelton, Allan H. White Jan 2004

Phytochemical And Larvicidal Studies On Stemona Curtisii: Structure Of A New Pyriodo[1,2-A]Azepine Stemona Alkaloid, Pitchaya Mungkornasawakul, Stephen G. Pyne, Araya Jatisatienr, Damrat Supyen, Chaiwat Jatisatienr, Wilford Lie, Alison T. Ung, Brian W. Skelton, Allan H. White

Faculty of Science - Papers (Archive)

A new pentacyclic Stemona alkaloid, stemocurtisinol (3), with a pyrido[1,2-a]azepine A,B-ring system, and the known pyrrolo[1,2-a]azepine alkaloid oxyprotostemonine (4) have been isolated from a root extract of S. curtisii. The structure and relative stereochemistry of stemocurtisinol was determined by spectral data interpretation and X-ray crystallography. This compound is a diastereoisomer of oxystemokerrin and has the opposite configuration at C-4 and C-19. The individual alkaloid components showed significant larvicidal activity (IC50 4−39 ppm) on mosquito larvae (Anopheles minimus HO).


Asymmetric Synthesis Of (+)-1-Epiaustraline And Attempted Synthesis Of Australine, Minyan Tang, Stephen G. Pyne Jan 2004

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

Faculty of Science - Papers (Archive)

A diastereoselective synthesis of the pyrrolizidine alkaloid, (+)-1-epiaustraline has been achieved via a diastereoselective syn-dihydroxylation of a pyrrolo[1,2-c]oxazol-3-one precursor that was readily prepared by a RCM reaction. Attempts to extend this methodology to the synthesis of australine were not successful since the final pyrrolidine ring closure to produce the desired pyrrolizidine of the target molecule was not productive.


Asymmetric Synthesis Of (-)-Swainsonine, Karl Lindsay, Stephen G. Pyne Jan 2004

Asymmetric Synthesis Of (-)-Swainsonine, Karl Lindsay, Stephen G. Pyne

Faculty of Science - Papers (Archive)

This paper describes a new synthesis of (-)-swainsonine via the ring-closing metathesis reaction of a substituted 3-allyl-4-vinyl-2-oxazolindinone and subsequent diastereoselective syn-dihydroxylation of the resulting pyrrolo[1,2-c]oxazol-3-one.


Studies On The Synthesis Of Croomine: Synthesis Of The Tricyclic B,C,D-Ring Core Structure, Karl B. Lindsay, Stephen G. Pyne Jan 2004

Studies On The Synthesis Of Croomine: Synthesis Of The Tricyclic B,C,D-Ring Core Structure, Karl B. Lindsay, Stephen G. Pyne

Faculty of Science - Papers (Archive)

A convergent and asymmetric synthesis of the tricyclic B,C,D-ring core structure of croomine has been achieved, using aminolysis reactions of chiral vinyl epoxides and the RCM reaction.


Phytochemical Studies On Stemona Burkillii Prain: Two New Dihydrostemofoline Alkaloids, Pitchaya Mungkornasawakul, Stephen G. Pyne, Araya Jatisatienr, Wilford Lie, Alison T. Ung, Kritchaya Issakul, Auntika Sawatwanich, Damrat Supyen, Chaiwat Jatisatienr Jan 2004

Phytochemical Studies On Stemona Burkillii Prain: Two New Dihydrostemofoline Alkaloids, Pitchaya Mungkornasawakul, Stephen G. Pyne, Araya Jatisatienr, Wilford Lie, Alison T. Ung, Kritchaya Issakul, Auntika Sawatwanich, Damrat Supyen, Chaiwat Jatisatienr

Faculty of Science - Papers (Archive)

Two new dihydrostemofoline alkaloids, 11(S),12(R)-dihydrostemofoline (3) and stemoburkilline (4), along with stemofoline (1) and 2’-hydroxystemofoline (2) have been isolated from a root extract of Stemona burkillii Prain. The structure and relative configuration of (3) have been determined via spectroscopic data and from comparison with synthetic 11(S),12(S)-dihydrostemofoline (5). The configuration of the exo-cyclic alkene group in (4) is tentively assigned as (E) based upon mechanistic considerations.


Asymmetric Synthesis Of Polyfunctionalized Pyrrolidines And Related Alkaloids, Stephen G. Pyne, Andrew S. Davis, Nicole Gates, Joseph Hartley, Karl Lindsay, Theeraphan Machan, Minyan Tang Jan 2004

Asymmetric Synthesis Of Polyfunctionalized Pyrrolidines And Related Alkaloids, Stephen G. Pyne, Andrew S. Davis, Nicole Gates, Joseph Hartley, Karl Lindsay, Theeraphan Machan, Minyan Tang

Faculty of Science - Papers (Archive)

This account describes our recent studies on the development of a general method of preparing polyfunctionalized pyrrolidine, indolizidine, pyrrolizidine and pyrrolo[1,2-a]azepines and their related alkaloids.


The Ad 1607 Coastal Flood In The Bristol Channel And Severn Estuary: Historical Records From Devon And Cornwall (Uk), S. K. Haslett, Edward A. Bryant Jan 2004

The Ad 1607 Coastal Flood In The Bristol Channel And Severn Estuary: Historical Records From Devon And Cornwall (Uk), S. K. Haslett, Edward A. Bryant

Faculty of Science - Papers (Archive)

The 1607 coastal flood was a high magnitude event that may have been the result of either a storm surge or a tsunami wave(s). Contemporary accounts describe the impacts of the surge/wave at Appledore and Barnstaple in North Devon, and a 19'x' century comment exists for Hayle in. Cornwall. An examination restricted to these local accounts reveals that the surge altitude or tsunami run-up at Appledore, at the estuary mouth, exceeded 8.5 in OD (a surge/wave height in excess of 3.28 in, possibly lip to c. 7-8 in), and at Barnstaple, about 12 km ...


Plasminogen Binding By Group A Streptococcal Isolates From A Tropical Region With Hyperendemic Streptococcal Skin Infection And A High Incidence Of Invasive Infection, F. C. Mckay, Jason D. Mcarthur, Martina L. Sanderson-Smith, S. Gardam, B. J. Currie, K. S. Sriprakash, P. K. Fagan, R. J. Towers, M. R. Batzloff, G. S. Chhatwal, Marie Ranson, Mark J. Walker Jan 2004

Plasminogen Binding By Group A Streptococcal Isolates From A Tropical Region With Hyperendemic Streptococcal Skin Infection And A High Incidence Of Invasive Infection, F. C. Mckay, Jason D. Mcarthur, Martina L. Sanderson-Smith, S. Gardam, B. J. Currie, K. S. Sriprakash, P. K. Fagan, R. J. Towers, M. R. Batzloff, G. S. Chhatwal, Marie Ranson, Mark J. Walker

Faculty of Science - Papers (Archive)

Reports of resurgence in invasive group A streptococcal (GAS) infections come mainly from affluent populations with infrequent exposure to GAS. In the tropical Northern Territory (NT) of Australia, high incidence of invasive GAS disease is secondary to endemic skin infection; serotype M1 clones are rare in invasive infection; the diversity and level of exposure to GAS strains is high and no particular strains dominate. Expression of a plasminogen-binding group A streptococcal M-like protein (PAM) has been associated with skin infection in isolates elsewhere (Bessen, D., C.M. Sotir, T.M. Readdy, and S.K. Hollingshead.1996. J. Infect. Dis. 173 ...


Quantitative Force Measurements In Liquid Using Frequency Modulation Atomic Force Microscopy, Suzi P. Jarvis, S. Akita, Takayuki Uchihashi, John E. Sader, Y. Nakayama, Michael J. Higgins, S Yasuda Jan 2004

Quantitative Force Measurements In Liquid Using Frequency Modulation Atomic Force Microscopy, Suzi P. Jarvis, S. Akita, Takayuki Uchihashi, John E. Sader, Y. Nakayama, Michael J. Higgins, S Yasuda

Faculty of Science - Papers (Archive)

The measurement of short-range forces with the atomic force microscope (AFM) typically requires implementation of dynamic techniques to maintain sensitivity and stability. While frequency modulation atomic force microscopy (FM-AFM) is used widely for high-resolution imaging and quantitative force measurements in vacuum, quantitative force measurements using FM-AFM in liquids have proven elusive. Here we demonstrate that the formalism derived for operation in vacuum can also be used in liquids, provided certain modifications are implemented. To facilitate comparison with previous measurements taken using surface forces apparatus, we choose a model system (octamethylcyclotetrasiloxane) that is known to exhibit short-ranged structural ordering when confined ...


Land-Based Activities And Impacts On Coral Reefs And The Marine Environment Of The Pacific Islands, Robert John Morrison, N. S. Tuivavalagi Jan 2004

Land-Based Activities And Impacts On Coral Reefs And The Marine Environment Of The Pacific Islands, Robert John Morrison, N. S. Tuivavalagi

Faculty of Science - Papers (Archive)

This paper recognizes the fact some of the problems encountered in the coral reefs and marine environment of the Pacific are actually due to land-based activities. This message needs to be clearly brought to the attention of farmers and others who work the land - as well as to fishermen and others whose activities focus on coral reefs and the marine environment.

The paper discusses the Pacific environment and some relevant key issues. The paper goes on to discuss land-based activities that harm the coral reef environment - with some emphasis on agricultural activities and soil erosion; however, the impacts of other ...


Charge-On-Spring Polarizable Water Models Revisited: From Water Clusters To Liquid Water To Ice, Haibo Yu, Wilfred Van Gunsteren Jan 2004

Charge-On-Spring Polarizable Water Models Revisited: From Water Clusters To Liquid Water To Ice, Haibo Yu, Wilfred Van Gunsteren

Faculty of Science - Papers (Archive)

The properties of two improved versions of charge-on-spring �COS� polarizable water models (COS/G2 and COS/G3) that explicitly include nonadditive polarization effects are reported. In COS models, the polarization is represented via a self-consistently induced dipole moment consisting of a pair of separated charges. A previous polarizable water model (COS/B2), upon which the improved versions are based, was developed by Yu, Hansson, and van Gunsteren �J. Chem. Phys. 118, 221 �2003��. To improve the COS/B2 model, which overestimated the dielectric permittivity, one additional virtual atomic site was used to reproduce the water monomer quadrupole moments besides the ...


The Development Of Signal Transduction Pathways During Epididymal Maturation Is Calcium Dependent, Heath W. Ecroyd, Kelly Asquith, Russell C. Jones, Robert J. Aitken Jan 2004

The Development Of Signal Transduction Pathways During Epididymal Maturation Is Calcium Dependent, Heath W. Ecroyd, Kelly Asquith, Russell C. Jones, Robert J. Aitken

Faculty of Science - Papers (Archive)

Capacitation has been correlated with the activation of a cAMP-PKA-dependent signaling pathway leading to protein tyrosine phosphorylation. The ability to exhibit this response to cAMP matures during epididymal maturation in concert with the ability of the sperrnatozoa to capacitate. In this study, we have addressed the mechanisms by which spermatozoa gain the potential to activate this signaling pathway during epididymal maturation. In a modified Tyrode's medium containing 1.7 mM calcium, caput spermatozoa had significantly higher [Ca2+](i) than caudal cells and could not tyrosine phosphorylate in response to cAMP. However, in calcium-depleted medium both caput and caudal cells ...


Analysis Of The Mechanism By Which Calcium Negatively Regulates The Tyrosine Phosphorylation Cascade Associated With Sperm Capacitation, Mark Baker, Louise Hethrington, Heath W. Ecroyd, Shaun D. Roman, Robert J. Aitken Jan 2004

Analysis Of The Mechanism By Which Calcium Negatively Regulates The Tyrosine Phosphorylation Cascade Associated With Sperm Capacitation, Mark Baker, Louise Hethrington, Heath W. Ecroyd, Shaun D. Roman, Robert J. Aitken

Faculty of Science - Papers (Archive)

The capacitation of mammalian spermatozoa involves the activation of a cAMP-mediated signal transduction pathway that drives tyrosine phosphorylation via mechanisms that are unique to this cell type. Controversy surrounds the impact of extracellular calcium on this process, with positive and negative effects being recorded in independent publications. We clearly demonstrate that the presence of calcium in the external medium decreases tyrosine phosphorylation in both human and mouse spermatozoa. Under these conditions, a rise in intracellular pH was recorded, however, this event was not responsible for the observed changes in phosphotyrosine expression. Rather, the impact of calcium on tyrosine phosphorylation in ...


Compartmentalization Of Prion Isoforms Within The Reproductive Tract Of The Ram, Heath W. Ecroyd, Pierre Sarradin, Jean-Louis Dacheux, Jean-Luc Gatti Jan 2004

Compartmentalization Of Prion Isoforms Within The Reproductive Tract Of The Ram, Heath W. Ecroyd, Pierre Sarradin, Jean-Louis Dacheux, Jean-Luc Gatti

Faculty of Science - Papers (Archive)

Cellular prion protein (Prp(C)) is a glycoprotein usually associated with membranes via its glycosylphosphatidylinositol (GPI) anchor. The trans-conformational form of this protein (Prp(SC)) is the suggested agent responsible for transmissible neurodegenerative spongiform encephalopathies. This protein has been shown on sperm and in the reproductive fluids of males. Antibodies directed against the C-terminal sequence near the GPI-anchor site, an N-terminal sequence, and against the whole protein showed that the Prp isoforms were compartmentalized within the reproductive tract of the ram. Immunoblotting with the three antibodies showed that the complete protein and both N- and C-terminally truncated and glycosylated isoforms ...