Taxon interactions control the distributions of cryoconite bacteria colonizing a High Arctic ice cap

Microbial colonization of glacial ice surfaces incurs feedbacks which affect the melting rate of the ice surface. Ecosystems formed as microbe-mineral aggregates termed cryoconite locally reduce ice surface albedo and represent foci of biodiversity and biogeochemical cycling. Consequently, greater understanding the ecological processes in the formation of functional cryoconite ecosystems upon glacier surfaces is sought. Here we present the first bacterial biogeography of an ice cap, evaluating the respective roles of dispersal, environmental and biotic filtration occurring at local scales in the assembly of cryoconite microbiota. 16S rRNA gene amplicon semiconductor sequencing of cryoconite colonizing a Svalbard ice cap coupled with digital elevation modelling of physical parameters reveals the bacterial community is dominated by a ubiquitous core of generalist taxa, with evidence for a moderate pairwise distance-decay relationship. While geographic position and melt season duration are prominent among environmental predictors of community structure, the core population of taxa appears highly influential in structuring the bacterial community. Taxon co-occurrence network analysis reveals a highly modular community structured by positive interactions with bottleneck taxa, predominantly Actinobacteria affiliated to isolates from soil humus. In contrast, the filamentous cyanobacterial taxon (assigned to Leptolyngbya) which dominates the community and bind together granular cryoconite are poorly connected to other taxa. While our study targeted one ice cap, the prominent role of generalist core taxa with close environmental relatives across the global cryosphere indicate discrete roles for cosmopolitan Actinobacteria and Cyanobacteria as respective keystone taxa and ecosystem engineers of cryoconite ecosystems colonizing ice caps. This article is protected by copyright. All rights reserved

Infectious Fear: The Rhetoric of Pestilence in Middle English Didactic Texts on Death

This article examines literary references to bubonic plague in a sample of late fourteenth- and fifteenth-century English texts that are didactic in tone and address the theme of death, including Geoffrey Chaucer’s “The Pardoner’s Tale”, John Lydgate’s “Danse Macabre” and the anonymous The Castle of Perseverance and “A Disputation between the Body and Worms”. Although there have been broad surveys of bubonic plague in Middle English literature, as well as studies of isolated texts, this article is the first to examine the role of pestilence in a group of texts linked by theme and authorial intention. It contributes to current understanding of the disease in late medieval literature and culture, showing how authors utilised the idea of pestilence as a frightening cause of sudden death and as a form of rhetoric serving to encourage readers to reflect on mortality, the spiritual health of the soul and the prospect of salvation. Whereas previous research has shown that doctors, priests and writers interpreted the pestilence as a divine punishment for sin, this study demonstrates how that belief could be exploited for rhetorical purposes. The rhetoric of pestilence emerges as a powerful contemplative tool urging readers to practise self-examination, penitence and a more active, strategic approach to death

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead