La Trobe University

About: La Trobe University is a education organization based out in Melbourne, Victoria, Australia. It is known for research contribution in the topics: Population & Health care. The organization has 13370 authors who have published 41291 publications receiving 1138269 citations. The organization is also known as: LaTrobe University & LTU.

Effects of creatine phosphate and P(i) on Ca2+ movements and tension development in rat skinned skeletal muscle fibres.

Abstract: 1. Mechanically skinned fast-twitch (FT) and slow-twitch (ST) muscle fibres of the rat were used to investigate the effects of fatigue-like changes in creatine phosphate (CP) and inorganic phosphate (P(i)) concentration on Ca(2+)-activation properties of the myofilaments as well as Ca2+ movements into and out of the sarcoplasmic reticulum (SR). 2. Decreasing CP from 50 mM to zero in FT fibres increased maximum Ca(2+)-activated tension (Tmax) by 16 +/- 2% and shifted the mid-point of the tension-pCa relation (pCa50) to the left by 0.28 +/- 0.03 pCa units. In ST fibres, a decrease of CP from 25 mM to zero increased Tmax by 9 +/- 1% and increased the pCa50 by 0.16 +/- 0.01 pCa units. The effect of CP on Tmax was suppressed in both fibre types by prior treatment with 0.3 mM FDNB (1-fluoro-2,4-dinitrobenzene), suggesting that these effects may occur via changes in creatine kinase activity. 3. Increases of P(i) in the range 0-50 mM reduced the pCa50 and Tmax in both fibre types. These effects were more pronounced in ST fibres than in FT fibres in absolute terms. However, normalization of the results to resting P(i) levels appropriate to both fibre types (1 mM for FT and 5 mM for ST fibres) revealed similar decreases in Tmax (approximately 39% at 25 mM P(i) and approximately 48% at 50 mM P(i)) and pCa50 (0.25 pCa units at 25-50 mM P(i)). The depressant action of P(i) on both parameters was considerably reduced when the rise in P(i) was accompanied by an equivalent reduction in [CP]. 4. Tension development in the presence of complex, fatigue-like milieu changes (40 mM P(i) for FT; 20 mM P(i) for ST) was decreased by 35-40% at a constant myoplasmic [Ca2+] of 6 microM in both fibre types. 5. SR Ca2+ loading at a myoplasmic [Ca2+] of 100 nM was found to increase abruptly when the [P(i)] during loading was increased to near 9 mM. At a myoplasmic [Ca2+] of 300 nM, the threshold P(i) for this effect dropped to approximately 3 mM. 6. Tension responses evoked by caffeine in the absence of P(i) were smaller and slower to peak if fibres were exposed to P(i) in a restricted myoplasmic Ca2+ pool after SR Ca2+ loading. This indicated that myoplasmic P(i) can decrease and prolong the rate of Ca2+ release from the SR.(ABSTRACT TRUNCATED AT 400 WORDS)

Relative importance of plastic vs genetic factors in adaptive differentiation: geographical variation for stress resistance in Drosophila melanogaster from eastern Australia

Abstract: Summary 1 Heritable clinal patterns for stress resistance traits have been described in a number of invertebrate species but patterns are usually characterized on populations reared under constant conditions. Here we examined the impact of simulated seasonal variation in temperature/photoperiod as well as constant conditions on stress resistance in eight Drosophila melanogaster populations from eastern Australia across a latitude range of 27 degrees. 2 Desiccation resistance was relatively higher under summer compared with winter/constant conditions, but this trait and starvation resistance did not exhibit clinal variation. Winter conditions increased cold resistance as measured by chill coma recovery time, and decreased heat resistance as measured by time to knock down in a vial. 3 Clinal patterns were evident for the thermal resistance traits regardless of conditions, and involved increased heat resistance and decreased cold resistance in tropical populations. Latitudinal patterns were steeper for cold resistance than for heat resistance. 4 To compare the relative impact of plastic vs genetic changes along the cline, differences in trait means were expressed relative to differences between populations from cline ends. For cold and heat resistance, differences between environmental conditions were approximately 1·5× greater than the heritable differences.

The growing applications of SuFEx click chemistry

Abstract: SuFEx (Sulfur Fluoride Exchange) is a modular, next generation family of click reactions, geared towards the rapid and reliable assembly of functional molecules. This review discusses the growing number of applications of SuFEx, which can be found in nearly all areas of modern chemistry; from drug discovery to materials science.

Technology-Facilitated Sexual Violence: A Literature Review of Empirical Research.

Abstract: Technology-facilitated sexual violence (TFSV) refers to a range of behaviors where digital technologies are used to facilitate both virtual and face-to-face sexually based harms. Such behaviors include online sexual harassment, gender- and sexuality-based harassment, cyberstalking, image-based sexual exploitation, and the use of a carriage service to coerce a victim into an unwanted sexual act. This article reviews the current state of knowledge on these different dimensions, drawing on existing empirical studies. While there is a growing body of research into technology-facilitated harms perpetrated against children and adolescents, there is a dearth of qualitative and quantitative research on TFSV against adults. Moreover, few of the existing studies provide reliable data on the nature, scope, and impacts of TFSV. Preliminary studies, however, indicate that some harms, much like sexual violence more broadly, may be predominantly gender-, sexuality-, and age-based, with young women being overrepresented as victims in some categories. This review collects the empirical evidence to date regarding the prevalence and gender-based nature of TFSV against adults and discusses the implications for policy and programs, as well as suggestions for future research.