Expected future plague levels in a wildlife host under different scenarios of climate change

We predicted future plague and black-tailed prairie dog dynamics in the North American prairies under different scenarios of climate change. A climate-driven model for the joint dynamic of the host–parasite system was used. Projections for the regional climate were obtained through empirical–statistical downscaling of global climate scenarios generated by an ensemble of global climate models for the recent Fourth Assessment Report by the IPCC. The study shows the uncertainties involved in predicting future regional climate and climate-driven population dynamics, but reveals that unchanged or lower levels of plague, leading to increased black-tailed prairie dog colonies, can be expected. Less plague is particularly expected for scenarios that assume the highest emission of greenhouse gases associated with the greatest projected future warming. Moreover, under high-emission scenarios, decreased probabilities of extremely high numbers of infected colonies are expected, along with decreased probabilities of extremely low total numbers of colonies. The assumed main underlying mechanism is an inhibiting effect of high temperatures on fleas (dispersal vector) and on flea-mediated transmission of the disease-causing bacterium. Our study highlights the importance of using dynamic ecological (here host–parasite) models together with ensembles of climate projections to investigate the responses of populations and parasites to a changed climate.     

Effects of experimental warming on arctic willows (Salix spp.): a comparison of responses from the Canadian High Arctic, Alaskan Arctic, and Swedish Subarctic

Three species of dwarf, prostrate willow ( Salix arctica , S. rotundifolia and S. herbacea ) were subjected to experimental summer warming in high arctic Canada, arctic Alaska, and subarctic Sweden, respectively, as part of the International Tundra Experiment. Phenological and growth responses of these species were compared for the second season of the experiment. Stigmas became receptive and pollen dispersal occurred significantly earlier for S. rotundifolia and S. herbacea in the ITEX open-top chambers, but not for S. arctica . Warming had no effect on the timing of seed dispersal, leaf yellowing, or leaf senescence. The length and dry weight of the largest leaves were greater for warmed plants, and was significant for S. rotundifolia . The number of catkins/plot did not differ among species or treatments, but the fruit : flower ratio was reduced in the experimental plots.     

Population genetic structure of North Atlantic, Mediterranean Sea and Sea of Cortez fin whales, Balaenoptera physalus (Linnaeus 1758): analysis of mitochondrial and nuclear loci

Samples were collected from 407 fin whales, Balaenoptera physalus , at four North Atlantic and one Mediterranean Sea summer feeding area as well as the Sea of Cortez in the Pacific Ocean. For each sample, the sex, the sequence of the first 288 nucleotides of the mitochondrial (mt) control region and the genotype at six microsatellite loci were determined. A significant degree of divergence was detected at all nuclear and mt loci between North Atlantic/Mediterranean Sea and the Sea of Cortez. However, the divergence time estimated from the mt sequences was substantially lower than the time elapsed since the rise of the Panama Isthmus, suggesting occasional gene flow between the North Pacific and North Atlantic ocean after the separation of the two oceans. Within the North Atlantic and Mediterranean Sea, significant levels of heterogeneity were observed in the mtDNA between the Mediterranean Sea, the eastern (Spain) and the western (the Gulf of Maine and the Gulf of St Lawrence) North Atlantic. Samples collected off West Greenland and Iceland could not be unequivocally assigned to either of the two areas. The homogeneity tests performed using the nuclear data revealed significant levels of divergence only between the Mediterranean Sea and the Gulf of St Lawrence or West Greenland. In conclusion, our results suggest the existence of several recently diverged populations in the North Atlantic and Mediterranean Sea, possibly with some limited gene flow between adjacent populations, a population structure which is consistent with earlier population models proposed by Kellogg, Ingebrigtsen, and Sergeant.     

Fine Needle Aspiration Cytodiagnosis of Subacute (De Quervain's) Thyroiditis In an Endemic Goitre Area

Between 1977 and 1989 252 fine needle aspirates (FNAs) of the thyroid from patients with a clinical suspicion of subacute granulomatous (de Quervain's) thyroiditis were examined in the Department of Pathology of the University of Innsbruck, Austria. In the same period 31 cases with preoperative FNA were diagnosed histologically as subacute thyroiditis. Only in three of these cases were the cytological features of de Quervain's thyroiditis found in the preoperative FNA. However, in 13 of these 31 cases a cytological suspicion of malignancy was obtained. Subsequent histological examination revealed an acute phase inflammation of de Quervain's thyroiditis in most of these cases. We conclude that an accurate FNA diagnosis of de Quervain's thyroiditis, particularly in the acute stage, may cause difficulties due to a lack of typical features and the appearance of atypical thyroid follicular cells. For the cytopathologist, accurate clinical information relating to the possibility of de Quervain's thyroiditis is essential if unnecessary surgery is to be avoided.     

Very diverse CD8 T cell clonotypic responses after virus infections

We measured CD8 T cell clonotypic diversity to three epitopes recognized in C57BL/6 mice infected with mouse hepatitis virus, strain JHM, or lymphocytic choriomeningitis virus. We isolated epitope-specific T cells with an IFN-gamma capture assay or MHC class I/peptide tetramers and identified different clonotypes by Vbeta chain sequence analysis. In agreement with our previous results, the number of different clonotypes responding to all three epitopes fit a log-series distribution. From these distributions, we estimated that >1000 different clonotypes responded to each immunodominant CD8 T cell epitope; the response to a subdominant CD8 T cell epitope was modestly less diverse. These results suggest that T cell response diversity is greater by 1-2 orders of magnitude than predicted previously.     

A severe acute respiratory syndrome-associated coronavirus-specific protein enhances virulence of an attenuated murine coronavirus

Most animal species that can be infected with the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) do not reproducibly develop clinical disease, hindering studies of pathogenesis. To develop an alternative system for the study of SARS-CoV, we introduced individual SARS-CoV genes (open reading frames [ORFs]) into the genome of an attenuated murine coronavirus. One protein, the product of SARS-CoV ORF6, converted a sublethal infection to a uniformly lethal encephalitis and enhanced virus growth in tissue culture cells, indicating that SARS-CoV proteins function in the context of a heterologous coronavirus infection. Furthermore, these results suggest that the attenuated murine coronavirus lacks a virulence gene residing in SARS-CoV. Recombinant murine coronaviruses cause a reproducible and well-characterized clinical disease, offer virtually no risk to laboratory personnel, and should be useful for elucidating the role of SARS-CoV nonstructural proteins in viral replication and pathogenesis.