Contrasting patterns of climatic niche divergence in Trebouxia—A alade of lichen-forming algae.

Lichen associations are overwhelmingly supported by carbon produced by photosynthetic algal symbionts. These algae have diversified to occupy nearly all climates and continents; however, we have a limited understanding of how their climatic niches have evolved through time. Here we extend previous work and ask whether phylogenetic signal in, and the evolution of, climatic niche, varies across climatic variables, phylogenetic scales, and among algal lineages in Trebouxia—the most common genus of lichen-forming algae. Our analyses reveal heterogeneous levels of phylogenetic signal across variables, and that contrasting models of evolution underlie the evolution of climatic niche divergence. Together these analyses demonstrate the variable processes responsible for shaping climatic tolerance in Trebouxia, and provide a framework within which to better understand potential responses to climate change associated perturbations. Such predictions reveal a disturbing trend in which the pace at which modern climate change is proceeding will vastly exceed the rate at which Trebouxia climatic niches have previously evolved

Emergence of Fatal PRRSV Variants: Unparalleled Outbreaks of Atypical PRRS in China and Molecular Dissection of the Unique Hallmark

Porcine reproductive and respiratory syndrome (PRRS) is a severe viral disease in pigs, causing great economic losses worldwide each year. The causative agent of the disease, PRRS virus (PRRSV), is a member of the family Arteriviridae. Here we report our investigation of the unparalleled large-scale outbreaks of an originally unknown, but so-called “high fever” disease in China in 2006 with the essence of PRRS, which spread to more than 10 provinces (autonomous cities or regions) and affected over 2,000,000 pigs with about 400,000 fatal cases. Different from the typical PRRS, numerous adult sows were also infected by the “high fever” disease. This atypical PRRS pandemic was initially identified as a hog cholera-like disease manifesting neurological symptoms (e.g., shivering), high fever (40–42°C), erythematous blanching rash, etc. Autopsies combined with immunological analyses clearly showed that multiple organs were infected by highly pathogenic PRRSVs with severe pathological changes observed. Whole-genome analysis of the isolated viruses revealed that these PRRSV isolates are grouped into Type II and are highly homologous to HB-1, a Chinese strain of PRRSV (96.5% nucleotide identity). More importantly, we observed a unique molecular hallmark in these viral isolates, namely a discontinuous deletion of 30 amino acids in nonstructural protein 2 (NSP2). Taken together, this is the first comprehensive report documenting the 2006 epidemic of atypical PRRS outbreak in China and identifying the 30 amino-acid deletion in NSP2, a novel determining factor for virulence which may be implicated in the high pathogenicity of PRRSV, and will stimulate further study by using the infectious cDNA clone technique

The Lichen Connections of Black Fungi

Many black meristematic fungi persist on rock surfaces\u2014hostile and exposed habitats where high doses of radiation and periods of desiccation alternate with rain and temperature extremes. To cope with these extremes, rock-inhabiting black fungi show phenotypic plasticity and produce melanin as cell wall pigments. The rather slow growth rate seems to be an additional prerequisite to oligotrophic conditions. At least some of these fungi can undergo facultative, lichen-like associations with photoautotrophs. Certain genera presenting different lifestyles are phylogenetic related among the superclass Dothideomyceta. In this paper, we focus on the genus Lichenothelia, which includes border-line lichens, that is, associations of melanised fungi with algae without forming proper lichen thalli. We provide a first phylogenetic hypothesis to show that Lichenothelia belongs to the superclass Dothideomyceta. Further, culture experiments revealed the presence of co-occurring fungi in Lichenothelia thalli. These fungi are related to plant pathogenic fungi (Mycosphaerellaceae) and to other rock-inhabiting lineages (Teratosphaeriaceae). The Lichenothelia thallus-forming fungi represent therefore consortia of different black fungal strains. Our results suggest a common link between rock-inhabiting meristematic and lichen-forming lifestyles of ascomycetous fungi