Earthworms in the soil under a beet-cereal rotation after 24 years of no plowing with and without green manure

Annual plowing is helpful in controlling weeds, but it can also be detrimental to earthworms in the soil. In a now 24-year long-term trial in the dry¬lands of southwest Germany, it was investigated how the intensity of tillage (plow 30 cm deep vs. goose share culti¬vator 15 cm deep) and the implementation of a green manure every 3rd year within the crop rotation (with vs. without) affects earthworm population. The follo¬wing two questions were the main focus: (1) Does the earthworm population suffer over time due to the low humus regene¬ration capacity of the beet-cereal crop rota¬tion with straw removal and without organic fertilization? (2) Can the negative effect of low humus-regeneration capacity be compensated by earthworm-promoting measures such as no plowing and green manuring? In the 9 years from the first to the second campaign, earthworm biomass decreased by about 30 % (mean across all variants). With one exception, earthworm biomass was always lower in the plowed soil than in the corresponding cultivator variant. For endogeic earthworms, plowing - especially in combination with green manure - was even rather positive. Generally, earthworms benefited more from green manuring than from reduced tillage

Mechanistic insights into the three steps of poly(ADP-ribosylation) reversal

Poly(ADP-ribosyl)ation (PAR) is a versatile and complex posttranslational modification composed of repeating units of ADP-ribose arranged into linear or branched polymers. This scaffold is linked to the regulation of many of cellular processes including the DNA damage response, alteration of chromatin structure and Wnt signalling. Despite decades of research, the principles and mechanisms underlying all steps of PAR removal remain actively studied. In this work, we synthesise well-defined PAR branch point molecules and demonstrate that PARG, but not ARH3, can resolve this distinct PAR architecture. Structural analysis of ARH3 in complex with dimeric ADP-ribose as well as an ADP-ribosylated peptide reveal the molecular basis for the hydrolysis of linear and terminal ADP-ribose linkages. We find that ARH3-dependent hydrolysis requires both rearrangement of a catalytic glutamate and induction of an unusual, square-pyramidal magnesium coordination geometry.publishe