Corbetthesselberg0053

Marine environments have increased in temperature by an average of 1°C since pre-industrial (1850) times [1]. Given that species ranges are closely allied to physiological thermal tolerances in marine organisms [2], it may therefore be expected that ocean warming would lead to abundance increases at poleward side of ranges and abundance declines toward the equator [3]. Here, we report a global analysis of abundance trends of 304 widely distributed marine species over the last century, across a range of taxonomic groups from phytoplankton to fish and marine mammals. Specifically, using a literature database, we investigate the extent that the direction and strength of long-term species abundance changes depend on the sampled location within the latitudinal range of species. Nintedanib order Our results show that abundance increases have been most prominent where sampling has taken place at the poleward side of species ranges, and abundance declines have been most prominent where sampling has taken place at the equatorward side of species ranges. These data provide evidence of omnipresent large-scale changes in abundance of marine species consistent with warming over the last century and suggest that adaptation has not provided a buffer against the negative effects of warmer conditions at the equatorward extent of species ranges. On the basis of these results, we suggest that projected sea temperature increases of up to 1.5°C over pre-industrial levels by 2050 [4] will continue to drive latitudinal abundance shifts in marine species, including those of importance for coastal livelihoods. Investigating the evolution of plant biochemistry is challenging because few metabolites are preserved in fossils and because metabolic networks are difficult to experimentally characterize in diverse extant organisms. We report a comparative computational approach based on whole-genome metabolic pathway databases of eight species representative of major plant lineages, combined with homologous relationships among genes of 72 species from streptophyte algae to angiosperms. We use this genomic approach to identify metabolic gains and losses during land plant evolution. We extended our findings with additional analysis of 305 non-angiosperm plant transcriptomes. Our results revealed that genes encoding the complete biosynthetic pathway for brassinosteroid phytohormones and enzymes for brassinosteroid inactivation are present only in spermatophytes. Genes encoding only part of the biosynthesis pathway are present in ferns and lycophytes, indicating a stepwise evolutionary acquisition of this pathway. Nevertheless, brassinosteroids are ubiquitous in land plants, suggesting that brassinosteroid biosynthetic pathways differ between earlier- and later-diverging lineages. Conversely, genes for gibberellin biosynthesis and inactivation using methyltransferases are found in all land plant lineages. This suggests that bioactive gibberellins might be present in bryophytes, although they have yet to be detected experimentally. We also found that cytochrome P450 oxidases involved in cutin and suberin production are absent in genomes of non-angiosperm plants that nevertheless do contain these biopolymers. Overall, we identified significant differences in crucial metabolic processes between angiosperms and earlier-diverging land plants and resolve details of the evolutionary history of several phytohormone and structural polymer biosynthetic pathways in land plants. ATP-binding cassette (ABC) transporters are the largest family of ATP-hydrolyzing transporters, which import or export substrates across membranes, and have members in every sequenced genome. Structural studies and biochemistry highlight the contrast between the global structural similarity of homologous transporters and the enormous diversity of their substrates. How do ABC transporters evolve to carry such diverse molecules and what variations in their amino acid sequence alter their substrate selectivity? We mutagenized the transmembrane domains of a conserved fungal ABC transporter that exports a mating pheromone and selected for mutants that export a non-cognate pheromone. Mutations that alter export selectivity cover a region that is larger than expected for a localized substrate-binding site. Individual selected clones have multiple mutations, which have broadly additive contributions to specific transport activity. Our results suggest that multiple positions influence substrate selectivity, leading to alternative evolutionary paths toward selectivity for particular substrates and explaining the number and diversity of ABC transporters. Traction forces are generated by cellular actin-myosin system and transmitted to the environment through adhesions. They are believed to drive cell motion, shape changes, and extracellular matrix remodeling [1-3]. However, most of the traction force analysis has been performed on stationary cells, investigating forces at the level of individual focal adhesions or linking them to static cell parameters, such as area and edge curvature [4-10]. It is not well understood how traction forces are related to shape changes and motion, e.g., forces were reported to either increase or drop prior to cell retraction [11-15]. Here, we analyze the dynamics of traction forces during the protrusion-retraction cycle of polarizing fish epidermal keratocytes and find that forces fluctuate together with the cycle, increasing during protrusion and reaching maximum at the beginning of retraction. We relate force dynamics to the recently discovered phenomenological rule [16] that governs cell-edge behavior during keratocyte polarization both traction forces and probability of switch from protrusion to retraction increase with the distance from the cell center. Diminishing forces with cell contractility inhibitor leads to decreased edge fluctuations and abnormal polarization, although externally applied force can induce protrusion-retraction switch. These results suggest that forces mediate distance sensitivity of the edge dynamics and organize cell-edge behavior, leading to spontaneous polarization. Actin flow rate did not exhibit the same distance dependence as traction stress, arguing against its role in organizing edge dynamics. Finally, using a simple model of actin-myosin network, we show that force-distance relationship might be an emergent feature of such networks.