The Self Model and the Conception of Biological Identity in Immunology

The self/non-self model, first proposed by F.M. Burnet, has dominated immunology for sixty years now. According to this model, any foreign element will trigger an immune reaction in an organism, whereas endogenous elements will not, in normal circumstances, induce an immune reaction. In this paper we show that the self/non-self model is no longer an appropriate explanation of experimental data in immunology, and that this inadequacy may be rooted in an excessively strong metaphysical conception of biological identity. We suggest that another hypothesis, one based on the notion of continuity, gives a better account of immune phenomena. Finally, we underscore the mapping between this metaphysical deflation from self to continuity in immunology and the philosophical debate between substantialism and empiricism about identity

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

A 3,4-dimethoxy-1,8-naphthalimide for lipid droplet imaging in live and fixed cells

Lipid droplets (LDs) are found in most eukaryotic cells and in addition to serving as lipid reservoirs, these highly dynamic organelles play fundamental roles in cell metabolism and growth. The study of LDs and their in- teractions with other cellular compartments provides new insights into normal cell biology and disease processes such as virus packaging, metabolic disorders, and cancer progression. Here we report the synthesis and comprehensive evaluation of two readily prepared, low molecular weight 3,4-dimethoxy-1,8-naphthalimides, as selective LD stains. The newly synthesised 1,8-naphthalimide derivative (DMN-LD), demonstrated impressive versatility compared to currently available options, by staining LDs in both live and fixed cells, as well as a three- dimensional spheroid, using both single and two-photon excitation. This new imaging agent has the potential to further unravel the complex biology of LDs, which are essential to cell survival, and when altered, underpin many disease states.Ian R.D. Johnson, Elley E. Rudebeck, Martin J. Sweetman, Alexandra Sorvina, Trent D. Ashton, Frederick M. Pfeffer, Douglas A. Brooks, Shane M. Hicke