Explicit nomenclature and classification in Pliny’s Natural History XXXII

Pliny’s Natural History has been traditionally considered as the unoriginal work of an uncritical compiler. This has also been held to be true of the “biological” books, especially when one compares them with the works of Aristotle, one of Pliny’s main authorities in this domain. Aristotle’s achievements would be remarkable, especially in the field of classification, of which the philosopher is traditionally celebrated as the scientific father. However, by carefully reading HN XXXII it is possible to find a certain “taxonomic” awareness—as, for instance, the need for a more accurate nomenclature in order to distinguish some aquatic animals beyond the proliferation of different vernacular terms—which is not to be found in the works of Aristotle. This, in a rather positivist way, may seem to anticipate Renaissance naturalists, but is in fact the consequence of both Pliny’s encyclopedic project and contingent ethnobiological, linguistic and social factors.     

Interleukin-2 gene variation impairs regulatory T cell function and causes autoimmunity

Autoimmune diseases are thought to result from imbalances in normal immune physiology and regulation. Here, we show that autoimmune disease susceptibility and resistance alleles on mouse chromosome 3 (Idd3) correlate with differential expression of the key immunoregulatory cytokine interleukin-2 (IL-2). In order to test directly that an approximately twofold reduction in IL-2 underpins the Idd3-linked destabilization of immune homeostasis, we show that engineered haplodeficiency of Il2 gene expression not only reduces T cell IL-2 production by twofold but also mimics the autoimmune dysregulatory effects of the naturally occurring susceptibility alleles of Il2. Reduced IL-2 production achieved by either genetic mechanism correlates with reduced function of CD4(+) CD25(+) regulatory T cells, which are critical for maintaining immune homeostasis.     

Landscape of transcription in human cells

Eukaryotic cells make many types of primary and processed RNAs that are found either in specific subcellular compartments or throughout the cells. A complete catalogue of these RNAs is not yet available and their characteristic subcellular localizations are also poorly understood. Because RNA represents the direct output of the genetic information encoded by genomes and a significant proportion of a cell's regulatory capabilities are focused on its synthesis, processing, transport, modification and translation, the generation of such a catalogue is crucial for understanding genome function. Here we report evidence that three-quarters of the human genome is capable of being transcribed, as well as observations about the range and levels of expression, localization, processing fates, regulatory regions and modifications of almost all currently annotated and thousands of previously unannotated RNAs. These observations, taken together, prompt a redefinition of the concept of a gene.     

Sex-specific volatile compounds influence microarthropod-mediated fertilization of moss

Sexual reproduction in non-vascular plants requires unicellular free-motile sperm to travel from male to female reproductive structures across the terrestrial landscape. Recent data suggest that microarthropods can disperse sperm in mosses. However, little is known about the chemical communication, if any, that is involved in this interaction or the relative importance of microarthropod dispersal compared to abiotic dispersal agents in mosses. Here we show that tissues of the cosmopolitan moss Ceratodon purpureus emit complex volatile scents, similar in chemical diversity to those described in pollination mutualisms between flowering plants and insects, that the chemical composition of C. purpureus volatiles are sex-specific, and that moss-dwelling microarthropods are differentially attracted to these sex-specific moss volatile cues. Furthermore, using experimental microcosms, we show that microarthropods significantly increase moss fertilization rates, even in the presence of water spray, highlighting the important role of microarthropod dispersal in contributing to moss mating success. Taken together, our results indicate the presence of a scent-based 'plant-pollinator-like' relationship that has evolved between two of Earth's most ancient terrestrial lineages, mosses and microarthropods.     

The early proofs of the theorem of Campbell, Baker, Hausdorff, and Dynkin

The aim of this paper is to provide a comprehensive exposition of the early contributions to the so-called Campbell, Baker, Hausdorff, Dynkin Theorem during the years 1890–1950. Related works by Schur, Poincaré, Pascal, Campbell, Baker, Hausdorff, and Dynkin will be investigated and compared. For a full recovery of the original sources, many mathematical details will also be furnished. In particular, we rediscover and comment on a series of five notable papers by Pascal (Lomb Ist Rend, 1901–1902), which nowadays are almost forgotten.