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.

Immunoglobulin G Subclass-Specific Responses against Plasmodium falciparum Merozoite Antigens Are Associated with Control of Parasitemia and Protection from Symptomatic Illness

Abstract: Substantial evidence indicates that antibodies to Plasmodium falciparum merozoite antigens play a role in protection from malaria, although the precise targets and mechanisms mediating immunity remain unclear. Different malaria antigens induce distinct immunoglobulin G (IgG) subclass responses, but the importance of different responses in protective immunity from malaria is not known and the factors determining subclass responses in vivo are poorly understood. We examined IgG and IgG subclass responses to the merozoite antigens MSP1-19 (the 19-kDa C-terminal region of merozoite surface protein 1), MSP2 (merozoite surface protein 2), and AMA-1 (apical membrane antigen 1), including different polymorphic variants of these antigens, in a longitudinal cohort of children in Papua New Guinea. IgG1 and IgG3 were the predominant subclasses of antibodies to each antigen, and all antibody responses increased in association with age and exposure without evidence of increasing polarization toward one subclass. The profiles of IgG subclasses differed somewhat for different alleles of MSP2 but not for different variants of AMA-1. Individuals did not appear to have a propensity to make a specific subclass response irrespective of the antigen. Instead, data suggest that subclass responses to each antigen are generated independently among individuals and that antigen properties, rather than host factors, are the major determinants of IgG subclass responses. High levels of AMA-1-specific IgG3 and MSP1-19-specific IgG1 were strongly predictive of a reduced risk of symptomatic malaria and high-density P. falciparum infections. However, no antibody response was significantly associated with protection from parasitization per se. Our findings have major implications for understanding human immunity and for malaria vaccine development and evaluation.

Fission-track ages of stone tools and fossils on the east Indonesian island of Flores

Abstract: The islands of Wallacea, located between the Southeast Asian (Sunda) and Australian (Sahul) continental areas, offer unique potential for the study of evolution and cultural change. Located east of Java and Bali, which were periodically connected to the Asian mainland, the Wallacean islands could only be reached by sea crossings. Consequently, before human intervention all these islands had impoverished faunas comprising only species that were capable of crossing water by swimming, rafting on flotsam, or by flying in sufficient numbers to establish biologically viable populations1. Here we report zircon fission-track dates from two fossil sites on the Wallacean island of Flores. Tangi Talo, which has an endemic fauna, dates to 0.90 ± 0.07 Myr bp, whereas Mata Menge, where stone tools are found with elements of continental Southeast Asian fauna, dates to between 0.88 ± 0.07 and 0.80 ± 0.07 Myr bp. Even at times when the sea level was lowest, water crossings were necessary to reach Flores from Southeast Asia. We conclude that Homo erectus in this region was capable of repeated water crossings using watercraft.

Optical dating of single and multiple grains of quartz from jinmium rock shelter, northern australia: part ii, results and implications*

Abstract: Quartz sediments from the floor deposit at Jinmium Rock Shelter have been investigated using the multiple-grain and single-grain optical dating methods described by Galbraith et al. (1999, this volume). Here we present the results of this dating programme and argue that the artefact-bearing sediments were deposited within the last 10 000 years. This time interval is consistent with the radiocarbon chronology but is much younger than previous claims for initial human occupation during the Pleistocene. Analysis of individual grains revealed also that the characteristic saturation doses of some grains are unusually high, which may permit dating of deposits older than a few hundred thousand years. Such grain-to-grain differences raise doubts, however, about the validity of using multiple-grain samples to investigate the phenomenology of quartz luminescence.

Climatic drivers of hemispheric asymmetry in global patterns of ant species richness

Abstract: Although many taxa show a latitudinal gradient in richness, the relationship between latitude and species richness is often asymmetrical between the northern and southern hemispheres. Here we examine the latitudinal pattern of species richness across 1003 local ant assemblages. We find latitudinal asymmetry, with southern hemisphere sites being more diverse than northern hemisphere sites. Most of this asymmetry could be explained statistically by differences in contemporary climate. Local ant species richness was positively associated with temperature, but negatively (although weakly) associated with temperature range and precipitation. After contemporary climate was accounted for, a modest difference in diversity between hemispheres persisted, suggesting that factors other than contemporary climate contributed to the hemispherical asymmetry. The most parsimonious explanation for this remaining asymmetry is that greater climate change since the Eocene in the northern than in the southern hemisphere has led to more extinctions in the northern hemisphere with consequent effects on local ant species richness.