Distribution, habitat preferences and population sizes of two threatened tree ferns, Cyathea cunninghamii and Cyathea x marcescens, in south-eastern Australia

The distribution, population sizes and habitat preferences of the rare tree ferns Cyathea cunninghamii Hook.f. (Slender Tree Fern) and F1 hybrid Cyathea x marcescens N.A.Wakef. (Skirted Tree Fern) in south-eastern Australia are described, together with the extension of the known distribution range of Cyathea cunninghamii from eastern Victoria into south-eastern New South Wales. Floristic and ecological data, encompassing most of the known habitat types, vegetation associations and population sizes, were collected across 120 locations. Additional information was sought from literature reviews, herbarium collections and field surveys of extant populations. Cyathea cunninghamii is widespread, with the majority of populations occurring in Tasmania and Victoria, one population in south-eastern NSW and a disjunct population in south-eastern Queensland; Cyathea x marcescens is confined to south and eastern Victoria and south and north eastern Tasmania. Both taxa occur on King Island in Bass Strait. Both taxa have a near coastal distribution with most populations occurring in sub-coastal hinterland and escarpment forests with a median altitude of 288 m. Hierarchical cluster analysis of floristic data across the species’ geographic range identified six vegetation communities ranging from rainforest to damp sclerophyll forest. Their micro-habitat preferences were consistently identified as steeply incised gullies of minor headwater streams of coastal and sub-coastal ranges with a plentiful moisture regime and geomorphic protection from extreme stream flow events, flooding and bank scouring. Sporophyte recruitment was associated with exposed soil of stream banks and edges of constructed walking tracks. Population sizes of both taxa are small with the majority of populations consisting of less than five adult individuals, with total populations of Cyathea cunninghamii and Cyathea x marcescens estimated at 919 and 221 mature individuals respectively. Population extinctions in Victoria and Tasmania have primarily been associated with outlier populations in regions subject to agricultural land clearance, habitat modification and changes to fire regimes in crown forests. Nonanthropogenic mortality was associated with land slips, tree falls and stream bank scouring by flood water. Conservation of the hybrid Cyathea x marcescens necessitates the preservation of habitats where both Cyathea cunninghamii and Cyathea australis occur in close proximity to substrates suitable for spore germination. In future, molecular techniques may prove useful for field identification of juvenile stages, facilitating selection of progeny of Cyathea cunninghamii and Cyathea x marcescens for cultivation and re-introduction to sites of previous or possible future extinctions

The Dynamical Implications of Multiple Stellar Formation Events in Galactic Globular Clusters

Various galactic globular clusters display abundance anomalies that affect the morphology of their colour-magnitude diagrams. In this paper we consider the possibility of helium enhancement in the anomalous horizontal branch of NGC 2808. We examine the dynamics of a self-enrichment scenario in which an initial generation of stars with a top-heavy initial mass function enriches the interstellar medium with helium via the low-velocity ejecta of its asymptotic giant branch stars. This enriched medium then produces a second generation of stars which are themselves helium-enriched. We use a direct N-body approach to perform five simulations and conclude that such two-generation clusters are both possible and would not differ significantly from their single-generation counterparts on the basis of dynamics. We find, however, that the stellar populations of such clusters would differ from single-generation clusters with a standard initial mass function and in particular would be enhanced in white dwarf stars. We conclude, at least from the standpoint of dynamics, that two-generation globular clusters are feasible.Comment: 24 pages, 7 figures, 3 tables. Accepted for publication in Ap

Development of a single nucleotide polymorphism array for population genomic studies in four European pine species

Pines are some of the most ecologically and economically important tree species in the world, and many have enormous natural distributions or have been extensively planted. However, a lack of rapid genotyping capability is hampering progress in understanding the molecular basis of genetic variation in these species. Here, we deliver an efficient tool for genotyping thousands of single nucleotide polymorphism (SNP) markers across the genome that can be applied to genetic studies in pines. Polymorphisms from resequenced candidate genes and transcriptome sequences of P. sylvestris, P. mugo, P. uncinata, P. uliginosa and P. radiata were used to design a 49,829 SNP array (Axiom_PineGAP, Thermo Fisher). Over a third (34.68%) of the unigenes identified from the P. sylvestris transcriptome were represented on the array, which was used to screen samples of four pine species. The conversion rate for the array on all samples was 42% (N = 20,795 SNPs) and was similar for SNPs sourced from resequenced candidate gene and transcriptome sequences. The broad representation of gene ontology terms by unigenes containing converted SNPs reflected their coverage across the full transcriptome. Over a quarter of successfully converted SNPs were polymorphic among all species, and the data were successful in discriminating among the species and some individual populations. The SNP array provides a valuable new tool to advance genetic studies in these species and demonstrates the effectiveness of the technology for rapid genotyping in species with large and complex genomes

Additional notes, corrections and sporophyte descriptions for Mesochaete (Bryopsida: Aulacomniaceae) in Australia.

The genus Mesochaete Lindb. is known from tropical to temperate regions of the east coast of mainland Australia and Lord Howe Island. It includes two species, M. undulata Lindb. and M. taxiforme (Hampe) Watts & Whitel. Leaf size, leaf cell dimensions and aspects of leaf cross-sectional anatomy appear to be the most reliable morphological features to distinguish the species and new information is given in support of their retention as separate species. Incorrect statements in the Flora of Australia and other Australian treatments are rectified. As there are no previous illustrations of the sporophyte of M. taxiforme, or descriptions of the peristome and spores of either taxon, complete illustrations of the two Mesochaete species are presented with a supplementary description of the sporophyte and, where available, SEMs of peristomes and spores. One of the taxa, M. taxiforme, was represented by very little fruiting material. Consequently, only one sporophyte was sacrificed for the SEM work. Morphologically, peristomes and spores of both taxa appear almost identical

SDF-1 chemokine signalling modulates the apoptotic responses to iron deprivation of clathrin-depleted DT40 cells.

We have previously deleted both endogenous copies of the clathrin heavy-chain gene in the chicken pre B-cell-line DT40 and replaced them with clathrin under the control of a tetracycline-regulatable promoter (Tet-Off). The originally derived cell-line DKO-S underwent apoptosis when clathrin expression was repressed. We have also described a cell-line DKO-R derived from DKO-S cells that was less sensitive to clathrin-depletion. Here we show that the restriction of transferrin uptake, resulting in iron deprivation, is responsible for the lethal consequence of clathrin-depletion. We further show that the DKO-R cells have up-regulated an anti-apoptotic survival pathway based on the chemokine SDF-1 and its receptor CXCR4. Our work clarifies several puzzling features of clathrin-depleted DT40 cells and reveals an example of how SDF-1/CXCR4 signalling can abrogate pro-apoptotic pathways and increase cell survival. We propose that the phenomenon described here has implications for the therapeutic approach to a variety of cancers.The work was supported by the following: Department of Biochemistry, University of Cambridge, BBSRC, and Marie Curie Fellowship (FRMW). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.This is the final version of the article. It was first available from PLOS via http://dx.doi.org/10.1371/journal.pone.010627

Trematodon (Bryopsida: Bruchiaceae) in Australia: unravelling the conundrum

Following a critical re-examination and evaluation of Australian taxa of the genus Trematodon, three species formerly considered endemic, T. baileyi Broth., T. brachyphyllus Müll. Hal., and T. longescens Müll. Hal., together with the New Caledonian endemic T. longifolius Broth. & Paris in Broth., are illustrated for the first time and reduced to synonyms of T. longicollis Michx

Macrophage transcriptional responses following in vitro infection with a highly virulent African swine fever virus isolate

We used a porcine microarray containing 2,880 cDNAs to investigate the response of macrophages to infection by a virulent African swine fever virus (ASFV) isolate, Malawi LIL20/1. One hundred twenty-five targets were found to be significantly altered at either or both 4 h and 16 h postinfection compared with targets after mock infection. These targets were assigned into three groups according to their temporal expression profiles. Eighty-six targets showed increased expression levels at 4 h postinfection but returned to expression levels similar to those in mock-infected cells at 16 h postinfection. These encoded several proinflammatory cytokines and chemokines, surface proteins, and proteins involved in cell signaling and trafficking pathways. Thirty-four targets showed increased expression levels at 16 h postinfection compared to levels at 4 h postinfection and in mock-infected cells. One host gene showed increased expression levels at both 4 and 16 h postinfection compared to levels in mock-infected cells. The microarray results were validated for 12 selected genes by quantitative real-time PCR. Levels of protein expression and secretion were measured for two proinflammatory cytokines, interleukin 1β and tumor necrosis factor alpha, during a time course of infection with either the virulent Malawi LIL20/1 isolate or the OUR T88/3 nonpathogenic isolate. The results revealed differences between these two ASFV isolates in the amounts of these cytokines secreted from infected cells

The unusual occurrence of green algal balls of <i>Chaetomorpha linum</i> on a beach in Sydney, Australia.

In spring 2014, thousands of green algal balls were washed up at Dee Why Beach, Sydney, New South Wales, Australia. Reports of algal balls are uncommon in marine systems, and mass strandings on beaches are even more rare, sparking both public and scientific interest. We identified the algal masses as Chaetomorpha linum by using light microscopy and DNA sequencing. We characterize the size and composition of the balls from Dee Why Beach and compare them to previous records of marine algal balls. We describe the environmental conditions that could explain their appearance, given the ecophysiology of C. linum

Multiple Populations in Globular Clusters: The Possible Contributions of Stellar Collisions

Globular clusters were thought to be simple stellar populations, but recent photometric and spectroscopic evidence suggests that the clusters' early formation history was more complicated. In particular, clusters show star-to-star abundance variations, and multiple sequences in their colour-magnitude diagrams. These effects seem to be restricted to globular clusters, and are not found in open clusters or the field. In this paper, we combine the two competing models for these multiple populations and include a consideration of the effects of stellar collisions. Collisions are one of the few phenomena which occur solely in dense stellar environments like (proto-)globular clusters. We find that runaway collisions between massive stars can produce material which has abundances comparable to the observed second generations, but that very little total mass is produced by this channel. We then add the contributions of rapidly-rotating massive stars (under the assumption that massive stars are spun up by collisions and interactions), and the contribution of asymptotic giant branch stars. We find that collisions can help produce the extreme abundances which are seen in some clusters. However, the total amount of material produced in these generations is still too small (by at least a factor of 10) to match the observations. We conclude with a discussion of the additional effects which probably need to be considered to solve this particular problem.Comment: 9 pages, 3 figures. Accepted by MNRA

The early phase transcriptome of bovine monocyte-derived macrophages infected with Staphylococcus aureus in vitro

BACKGROUND: In the mammary gland, local recruitment and action of macrophages is a key immunological defence mechanism against infection. Macrophages are members of the innate immune system, serve as the first line of the defence against invading pathogens and are critical effectors and regulators of inflammation. We have examined the early phase response of bovine macrophages to infection with live Staphylococcus aureus. Genome-wide transcript profiling of blood monocyte-derived macrophages from six Norwegian Red heifers infected with live S. aureus for 2 and 6 hours in vitro was performed. RESULTS: About 420 of the 17 000 genes on the ARK-Genomics bovine cDNA array were differentially regulated at 6 hours post infection. Approximately 70% of the responding genes had a known identity (Entrez Gene ID) and were used in the identification of overrepresented pathways and biological functions in the dataset. Analysis of a subset of differentially regulated genes (List eQG) obtained by comparison with data from genome-wide association mapping in Norwegian Red cattle identified anti-inflammatory cytokines interleukin 4 and interleukin 13 as putative expression quantitative trait loci, suggesting that S. aureus infection triggers alternative activation of macrophages. Moreover, several classical activation pathways were found, mainly cellular immune response and cytokine signaling pathways, i.e. triggering receptor expressed on myeloid cells 1 (TREM1) and nucleotide-binding and oligomerization domain-like receptor (NLR) pathways. Tumor necrosis factor receptor superfamily member 5 (CD40 ligand) was identified as an upstream regulator which points toward CD40 likely acting as a co-stimulatory receptor during Toll-like receptor 2(TLR2)-mediated inflammatory response of bovine macrophages to S. aureus infection. Furthermore, peptidoglycan was identified as an upstream regulator in the List eQG, which indicates that this bacterial cell-wall component might be pivotal in macrophage intracellular bacterial recognition during early inflammation. CONCLUSIONS: Here we have shown that in vitro infection of bovine macrophages with live S. aureus induced both alternative and classical activation pathways. Alternative activation of macrophages may be a mechanism contributing to intracellular persistence of S. aureus in the course of inflammation such as during mastitis in dairy cattle