Application of the British national vegetation classification to the communities of the park grass experiment through time

The Park Grass Experiment at Rothamsted consists of a series of fertilizer treatments which have been applied to a species-rich hay meadow annually since 1856. Detailed botanical analyses of the plots between 1862 and 1992 were classified to one of the National Vegetation Classification (NVC) communities using the similarity measured by Czekanowski coefficient using computer program MATCH. Results indicated that “control” unfertilized plots were a relatively stableCynosurus cristatus-Centaurea nigra dicotyledon-rich grassland. However mineral fertilized plots moved towards a species-richArrhenatherum elatius grassland MG1e after 50–80 years and remained there. Plots receiving nitrogen fertilizer moved first to MG1e then on to aLolium perenne-Alopecurus pratensis grassland MG7D. Perhaps the most interesting plot was one which received a low rate of the soil acidifying ammonium sulphate fertilizer; the species composition changed towards a MG7D (Lolium perenne-Alopecurus pratensis) community between 1856 and 1903 but since then a liming treatment has been applied to part of the plot and the species composition on that part has recovered to a MG5 community resembling the control plots, taking 70–90 years to do so.     

Structure of the Small Dictyostelium discoideum Myosin Light Chain MlcB Provides Insights into MyoB IQ Motif Recognition

Dictyostelium discoideum MyoB is a class I myosin involved in the formation and retraction of membrane projections, cortical tension generation, membrane recycling, and phagosome maturation. The MyoB-specific, single-lobe EF-hand light chain MlcB binds the sole IQ motif of MyoB with submicromolar affinity in the absence and presence of Ca²⁺. However, the structural features of this novel myosin light chain and its interaction with its cognate IQ motif remain uncharacterized. Here, we describe the NMR-derived solution structure of apoMlcB, which displays a globular four-helix bundle. Helix 1 adopts a unique orientation when compared with the apo states of the EF-hand calcium-binding proteins calmodulin, S100B, and calbindin D_9k. NMR-based chemical shift perturbation mapping identified a hydrophobic MyoB IQ binding surface that involves amino acid residues in helices I and IV and the functional N-terminal Ca²⁺ binding loop, a site that appears to be maintained when MlcB adopts the holo state. Complementary mutagenesis and binding studies indicated that residues Ile-701, Phe-705, and Trp-708 of the MyoB IQ motif are critical for recognition of MlcB, which together allowed the generation of a structural model of the apoMlcB-MyoB IQ complex. We conclude that the mode of IQ motif recognition by the novel single-lobe MlcB differs considerably from that of stereotypical bilobal light chains such as calmodulin.