Cnn1 inhibits the interactions between the KMN complexes of the yeast kinetochore

El pdf del artículo es la versión de autor.-- et al.Kinetochores attach the replicated chromosomes to the mitotic spindle and orchestrate their transmission to the daughter cells. Kinetochore-spindle binding and chromosome segregation are mediated by the multi-copy KNL1 Spc105, MIS12 Mtw1 and NDC80 Ndc80 complexes that form the so-called KMN network. KMN-spindle attachment is regulated by the AuroraB Ipl1 and MPS1 Mps1 kinases. It is unclear whether other mechanisms exist that support KMN activity during the cell cycle. Using budding yeast, we show that kinetochore protein Cnn1 localizes to the base of the Ndc80 complex and promotes a functionally competent configuration of the KMN network. Cnn1 regulates KMN activity in a spatiotemporal manner by inhibiting the interaction between its complexes. Cnn1 activity peaks in anaphase and is driven by the Cdc28, Mps1 and Ipl1 kinases. © 2012 Macmillan Publishers Limited. All rights reserved.P.D.W. acknowledges financial support from the Italian Association for Cancer Research (grant 8840). T.R.H. recognizes support from the N.I.H. (grant GM087461) and the American Cancer Society (grant IRG 58-006-50). T.U.T. acknowledges a Cancer Research U.K. senior fellowship and Wellcome Trust program grant. L.J.B. acknowledges a doctoral fellowship from the European School of Molecular Medicine.Peer Reviewe

The role of gill raker number variability in adaptive radiation of coregonid fish

Gill raker divergence is a general pattern in adaptive radiations of postglacial fish, but few studies have addressed the adaptive significance of this morphological trait in foraging and eco-evolutionary interactions among predator and prey. Here, a set of subarctic lakes along a diversifying gradient of coregonids was used as the natural setting to explore correlations between gill raker numbers and planktivory as well as the impact of coregonid radiation on zooplankton communities. Results from 19 populations covering most of the total gill raker number gradient of the genus Coregonus, confirm that the number of gill rakers has a central role in determining the foraging ability towards zooplankton prey. Both at the individual and population levels, gill raker number was correlated with pelagic niche use and the size of utilized zooplankton prey. Furthermore, the average body size and the abundance and diversity of the zooplankton community decreased with the increasing diversity of coregonids. We argue that zooplankton feeding leads to an eco-evolutionary feedback loop that may further shape the gill raker morphology since natural selection intensifies under resource competition for depleted prey communities. Eco-evolutionary interactions may thus have a central role creating and maintaining the divergence of coregonid morphs in postglacial lakes