James Cook University

About: James Cook University is a education organization based out in Townsville, Queensland, Australia. It is known for research contribution in the topics: Population & Coral reef. The organization has 9101 authors who have published 27750 publications receiving 1032608 citations. The organization is also known as: JCU.

Quantifying the Spatial Dimension of Dengue Virus Epidemic Spread within a Tropical Urban Environment

Abstract: Background Dengue infection spread in naive populations occurs in an explosive and widespread fashion primarily due to the absence of population herd immunity, the population dynamics and dispersal of Ae. aegypti, and the movement of individuals within the urban space. Knowledge on the relative contribution of such factors to the spatial dimension of dengue virus spread has been limited. In the present study we analyzed the spatio-temporal pattern of a large dengue virus-2 (DENV-2) outbreak that affected the Australian city of Cairns (north Queensland) in 2003, quantified the relationship between dengue transmission and distance to the epidemic's index case (IC), evaluated the effects of indoor residual spraying (IRS) on the odds of dengue infection, and generated recommendations for city-wide dengue surveillance and control.

Microplastic ingestion ubiquitous in marine turtles

Abstract: Despite concerns regarding the environmental impacts of microplastics, knowledge of the incidence and levels of synthetic particles in large marine vertebrates is lacking. Here, we utilize an optimized enzymatic digestion methodology, previously developed for zooplankton, to explore whether synthetic particles could be isolated from marine turtle ingesta. We report the presence of synthetic particles in every turtle subjected to investigation (n = 102) which included individuals from all seven species of marine turtle, sampled from three ocean basins (Atlantic [ATL]: n = 30, four species; Mediterranean (MED): n = 56, two species; Pacific (PAC): n = 16, five species). Most particles (n = 811) were fibres (ATL: 77.1% MED: 85.3% PAC: 64.8%) with blue and black being the dominant colours. In lesser quantities were fragments (ATL: 22.9%: MED: 14.7% PAC: 20.2%) and microbeads (4.8%; PAC only; to our knowledge the first isolation of microbeads from marine megavertebrates). Fourier transform infrared spectroscopy (FT‐IR) of a subsample of particles (n = 169) showed a range of synthetic materials such as elastomers (MED: 61.2%; PAC: 3.4%), thermoplastics (ATL: 36.8%: MED: 20.7% PAC: 27.7%) and synthetic regenerated cellulosic fibres (SRCF; ATL: 63.2%: MED: 5.8% PAC: 68.9%). Synthetic particles being isolated from species occupying different trophic levels suggest the possibility of multiple ingestion pathways. These include exposure from polluted seawater and sediments and/or additional trophic transfer from contaminated prey/forage items. We assess the likelihood that microplastic ingestion presents a significant conservation problem at current levels compared to other anthropogenic threats.

Cryptopatches and isolated lymphoid follicles: dynamic lymphoid tissues dispensable for the generation of intraepithelial lymphocytes

Abstract: In comparison to secondary lymphoid organs, gut-associated lymphoid tissues such as isolated lymphoid follicles (ILF) and cryptopatches (CP) have been less intensively studied. To gain a better insight into processes regulating organization and function of these structures, which are believed to participate in immune responses and extrathymic T cell development, we characterized the lymphoid structures of the murine small intestine in more detail. The size and cellular composition of small intestinal lymphoid aggregations were analyzed in C57BL/6 and BALB/c wild-type and lymphotoxin (LT)-deficient mice, by flow cytometry, histology and automated multi-color immunofluorescence microscopy evaluating large coherent areas of the intestine. These evaluations demonstrate that aggregated lymphoid structures in the small intestine vary in size and cellular composition, with a majority of structures not matching the current definitions of CP or ILF. Accordingly, significant variations depending on species, age and mouse strain were observed. Furthermore, small bowel transplantation revealed a rapid exchange of B but not T cells between host and grafted tissue. Moreover, LT-deficient animals lack any intestinal lymphoid aggregations yet possess the complete panel of intraepithelial lymphocytes (IEL). In summary, our observations disclose intestinal lymphoid aggregations as dynamic structures with a great deal of inborn plasticity and demonstrate their dispensability for the generation of IEL.

Experimental hybridization and breeding incompatibilities within the mating systems of mass spawning reef corals

Abstract: Synchronous spawning of many coral species that co-occur on Indo-Pacific reefs raises the possibility that hybridization plays a role in their evolution. Here we use experimental crosses to examine mating compatibilities and breeding barriers in a group of sessile animals whose mating systems are primarily governed by interactions among free-spawned gametes. We found hybridization occurs readily in more than one-third of 42 species pairs from the common genera Acropora, Montipora and Platygyra. Mean fertilization success ranged from 1% to 50% in species crosses, but standard deviations about these means were large and in some cases, fertilization success in individual colony matings was greater than 95%. Cases of high fertility in individual, interspecific matings were found in all three genera. Hybridization occurred most readily between species that were morphologically similar, identifying areas where current taxonomic judgements may require further testing. However, cases of significant hybridization also occurred between species that are morphologically distinct. Evidence of in vitro hybridization combined with the lack of either temporal or spatial barriers to interbreeding among field populations of these species, indicates that natural hybridization may occur commonly between congeneric corals that are currently recognized as distinct species. We also detected mating incompatibilities between some colonies within some species. In some cases, incompatible colonies corresponded to distinct morphotypes, but not in others. Thus some breeding groups in scleractinian corals are potentially larger, but others are smaller, than would be predicted using morphological criteria. Gamete incompatibilities within a morphospecies that readily hybridizes with other species may be the result of a mating system that is governed by gamete-level interactions. Imprecision in the alignment of morphological and breeding boundaries suggests a single species concept may not apply to scleractinian corals and challenges the tacit assumption that currently defined coral species encompass biological, evolutionary and phylogenetic species. Hybridization between supposedly isolated species introduces a reticulate nature to the evolution of corals and has profound implications for present understanding of the population genetics, phylogenetics, and evolutionary biology of scleractinian corals.