Mass Mortality of Adult Male Subantarctic Fur Seals: Are Alien Mice the Culprits?

Background: Mass mortalities of marine mammals due to infectious agents are increasingly reported. However, in contrast to previous die-offs, which were indiscriminate with respect to sex and age, here we report a land-based mass mortality of Subantarctic fur seals with apparent exclusivity to adult males. An infectious agent with a male-predilection is the most plausible explanation for this die-off. Although pathogens with gender-biased transmission and pathologies are unusual, rodents are known sources of male-biased infectious agents and the invasive Mus musculus house mouse, occurs in seal rookeries. Methodology / Principal Findings: Molecular screening for male-biased pathogens in this potential rodent reservoir host revealed the absence of Cardiovirus and Leptospirosis genomes in heart and kidney samples, respectively, but identified a novel Streptococcus species with 30 % prevalence in mouse kidneys. Conclusions / Significance: Inter-species transmission through environmental contamination with this novel bacterium, whose congenerics display male-bias and have links to infirmity in seals and terrestrial mammals (including humans)

Impact of glucocorticoid receptor density on ligand-independent dimerization, cooperative ligand-binding and basal priming of transactivation: a cell culture model

Glucocorticoid receptor (GR) levels vary between tissues and individuals and are altered by physiological and pharmacological effectors. However, the effects and implications of differences in GR concentration have not been fully elucidated. Using three statistically different GR concentrations in transiently transfected COS-1 cells, we demonstrate, using co-immunoprecipitation (CoIP) and fluorescent resonance energy transfer (FRET), that high levels of wild type GR (wtGR), but not of dimerization deficient GR (GRdim), display ligand-independent dimerization. Whole-cell saturation ligand-binding experiments furthermore establish that positive cooperative ligand-binding, with a concomitant increased ligand-binding affinity, is facilitated by ligand-independent dimerization at high concentrations of wtGR, but not GRdim. The down-stream consequences of ligand-independent dimerization at high concentrations of wtGR, but not GRdim, are shown to include basal priming of the system as witnessed by ligand-independent transactivation of both a GRE-containing promoter-reporter and the endogenous glucocorticoid (GC)-responsive gene, GILZ, as well as ligand-independent loading of GR onto the GILZ promoter. Pursuant to the basal priming of the system, addition of ligand results in a significantly greater modulation of transactivation potency than would be expected solely from the increase in ligand-binding affinity. Thus ligand-independent dimerization of the GR at high concentrations primes the system, through ligand-independent DNA loading and transactivation, which together with positive cooperative ligand-binding increases the potency of GR agonists and shifts the bio-character of partial GR agonists. Clearly GR-levels are a major factor in determining the sensitivity to GCs and a critical factor regulating transcriptional programs

The bii4africa dataset of faunal and floral population intactness estimates across Africa’s major land uses

Sub-Saharan Africa is under-represented in global biodiversity datasets, particularly regarding the impact of land use on species’ population abundances. Drawing on recent advances in expert elicitation to ensure data consistency, 200 experts were convened using a modified-Delphi process to estimate ‘intactness scores’: the remaining proportion of an ‘intact’ reference population of a species group in a particular land use, on a scale from 0 (no remaining individuals) to 1 (same abundance as the reference) and, in rare cases, to 2 (populations that thrive in human-modified landscapes). The resulting bii4africa dataset contains intactness scores representing terrestrial vertebrates (tetrapods: ±5,400 amphibians, reptiles, birds, mammals) and vascular plants (±45,000 forbs, graminoids, trees, shrubs) in sub-Saharan Africa across the region’s major land uses (urban, cropland, rangeland, plantation, protected, etc.) and intensities (e.g., large-scale vs smallholder cropland). This dataset was co-produced as part of the Biodiversity Intactness Index for Africa Project. Additional uses include assessing ecosystem condition; rectifying geographic/ taxonomic biases in global biodiversity indicators and maps; and informing the Red List of Ecosystems

The histopathology of Enterogyrus coronatus Pariselle, Lambert & Euzet, 1991 (Monogenoidea) in the stomach of the southern mouthbrooder Pseudocrenilabrus philander (Weber, 1897) (Cichlidae)

The aim of this study was to describe the histopathology of the stomach of the southern mouthbrooder Pseudocrenilabrus philander (Weber, 1897) naturally infected with an endoparasitic monogenoid, Enterogyrus coronatus Pariselle, Lambert and Euzet, 1991. A total of 16 host specimens were collected in February 2014 from Padda Dam (Gauteng province, Johannesburg, 26°17′ S, 27°99′ E). This monogenoid occurred at a prevalence of 56.3%, mean abundance of 2.6 and mean intensity of 4.2. Pieces of stomach tissue with parasites in situ were fixed and processed for routine histological investigations. The anchors and marginal hooks played important roles in the attachment of the parasite to the host. The parasites inserted the sharp curved terminal ends of their anchors into epithelial tissue, while the hooks penetrated superficially and lifted the epithelial tissue. This resulted in a secure attachment and, in most cases, parasites could only be dislodged from the host tissue with some difficulty by using a needle. The histopathological changes caused by the monogenoid on these wild fish were mild and restricted to the vicinity of haptoral attachment. Pleomorphism and mild metaplasia, vacuolation, and mild epithelial hyperplasia occurred in the vicinity of haptoral attachment.Keywords: cichlid, histopathology, Padda Dam, South Africa, southern mouthbroode

Innovative fluorescence detection technique for metals in cestode egg-shells

Recent work in the field of parasitology has drawn attention to the application of  parasites as pollution-accumulation indicators, particularly cestodes. A  discrepancy in metal concentrations within cestode posterior and anterior tissue has led researchers to attribute this phenomenon to metals binding to the shells of their eggs. Thus, the objective of this study was to demonstrate metal presence through the implementation of fluorochromy. Tissue forms of a known metal accumulator, Bothriocephalus  acheilognathi, were exposed to a Phen Green FL fluorescent probe specific for metal ions and examined with a fluorescence microscope. The results have shown that metal ions bind to the egg-shells of B. acheilognathi and that fluorescence microscopy can be employed successfully to demonstrate metal accumulation in tapeworms.Key words: Bothriocephalus acheilognathi, fluorochromy, metal accumulation, immunofluorescence, Phen Green FL