Cell elongation in rod-shaped bacteria is mediated by the Rod system, a conserved morphogenic complex that spatially controls cell wall (CW) assembly. In Escherichia coli, alterations in a CW synthase component of the system called PBP2 were identified that overcome other inactivating defects. Rod system activity was stimulated in the suppressors in vivo, and purified synthase complexes with these changes showed more robust CW synthesis in vitro. Polymerization of the actinlike MreB component of the Rod system was also found to be enhanced in cells with the activated synthase. The results suggest an activation pathway governing Rod system function in which PBP2 conformation plays a central role in stimulating both CW glycan polymerization by its partner RodA and the formation of cytoskeletal filaments of MreB to orient CW assembly. An analogous activation pathway involving similar enzymatic components is likely responsible for controlling CW synthesis by the division machinery.

Separation of duplicated spindle poles is the first step in forming the mitotic spindle. Kinesin-5 crosslinks and slides anti-parallel microtubules, but it is unclear how these two activities contribute to the first steps in spindle formation. In this study we report that in monopolar spindles, the duplicated spindle poles snap apart in a fast and irreversible step that produces a nascent bipolar spindle. Using mutations in Kinesin-5 that inhibit microtubule sliding, we show crosslinking alone drives the fast, irreversible pole separation. Electron tomography revealed microtubule pairs in monopolar spindles have short overlaps that intersect at high angles and are unsuited for ensemble Kinesin-5 sliding. However, maximal extension of a subset of microtubule pairs approaches the length of nascent bipolar spindles and is consistent with a Kinesin-5 crosslinking driven transition. Finally, stochastic microtubule sliding by Kinesin-5 stabilizes the nascent spindle and sets a stereotyped equilibrium length.pole separation velocity of 174 nm sec -1 , making it one of the fastest steps in spindle assembly.We report that mutations inhibiting Kinesin-5 MT sliding do not significantly change pole separation velocities. Using 3D electron tomography, we show that the MT structure of the initial monopolar state is comprised of short, high angle MT pairings that are unsuited to ensemble Kinesin-5 sliding. Nevertheless, this highly coupled system supports the maximal extension of crosslinked MTs required to achieve the bipolar state as measured for WT cells. We also find that the length and stability of the nascent bipolar spindle is dependent on Kinesin-5 MT sliding. We propose that while Kinesin-5 sliding does not specifically contribute to the monopolar to bipolar transition, both Kinesin-5 sliding and crosslinking are required to form a stereotyped, stable bipolar spindle. RESULTS The transition from monopolar to bipolar spindle is a fast, irreversible snapPrevious studies in both fission yeast (Rincon et al., 2017) and budding yeast (Crasta et al., 2006) demonstrated that Cin8 MT sliding is dispensable for forming a bipolar spindle.However, the velocity, irreversibility and efficiency of the transition in the presence or absence of Kinesin-5 sliding has not yet been measured. We defined spindle formation as a transition that

Reforestation is an important strategy for nature-based climate solutions and identifying carbon storage potential of different locations is critical to its success. Applying average carbon values from forest inventories ignores the spatial heterogeneity in forest carbon and the effects of forest edges on carbon storage degradation. Here we show how spatially-explicit, predictive carbon modeling, that leverages satellite, social and biogeophysical datasets, can be used to identify more efficient restoration opportunities for climate mitigation than area-based carbon stock averages. Accounting for regeneration of forest edges, in addition to reforestation, boosts estimates of potential carbon gains by more than 20%. The total potential carbon gain that could be achieved through reforestation at the level indicated by the Bonn Challenge (350Mha) is 51 Gt CO2-eq, but the "missing carbon" in our current forests accounts for 64.6 Gt CO2-eq globally; the greatest potential carbon gains are found in areas of high fragmentation.