The hierarchical packaging of eukaryotic chromatin plays a central role in transcriptional regulation and other DNA-related biological processes. Here, we report the 11-angstrom-resolution cryogenic electron microscopy (cryo-EM) structures of 30-nanometer chromatin fibers reconstituted in the presence of linker histone H1 and with different nucleosome repeat lengths. The structures show a histone H1-dependent left-handed twist of the repeating tetranucleosomal structural units, within which the four nucleosomes zigzag back and forth with a straight linker DNA. The asymmetric binding and the location of histone H1 in chromatin play a role in the formation of the 30-nanometer fiber. Our results provide mechanistic insights into how nucleosomes compact into higher-order chromatin fibers.

China's recent promotion of Corporate Social Responsibility (CSR) has coincided with a marked increase in the number of Chinese listed firms attracting female board members and foreign equity investors. Using Rankins' (RKS) ratings over the 2009 to 2013 period, we show that greater gender balance in top-management supports stronger CSR performance. This finding broadens gender-based accounts emphasizing social networks (Westphal and Milton, 2000), Critical Mass Theory (Kramer et al., 2006;Bear et al., 2010;and Soares et al., 2011) and team dynamics (Woolley et al., 2010;and Hoogendoorn et al., 2013). Findings also reveal stronger CSR performance in firms with a female CEO. Female leadership thus appears to be just as important as gender mix in driving CSR change.CSR ratings are also increasing in foreign ownership levels. We examine whether a political-networking motivation underlies foreign investment (Du and Girma, 2010;Liu et al., 2014a;Lin et al., 2015;and Jiang and Kim, 2015). We argue that qualified foreign institutional investors (QFIIs) deploy socialengagement in non-SOEs to build competitive advantage. But in SOEs, where strong political networks already exist, QFIIs have less incentive to boost CSR ratings. However, results indicate little difference in the social ratings of QFII-invested SOEs and non-SOEs.Additionally, we confirm the Barnea and Rubin (2010) contention of an inversion in social ratings at entrenched managerial ownership levels. Non-linear rating effects also emerge in relation to state ownership (Li et al., 2013). Finally, CSR performance exhibits positive (negative) relation with a listed entity's size and age (leverage and lagged return-on-equity) but virtually no connection with independent board representation.

In higher eukaryotes, the centromere is epigenetically specified by the histone H3 variant Centromere Protein-A (CENP-A). Deposition of CENP-A to the centromere requires histone chaperone HJURP (Holliday junction recognition protein). The crystal structure of an HJURP-CENP-A-histone H4 complex shows that HJURP binds a CENP-A-H4 heterodimer. The C-terminal b-sheet domain of HJURP caps the DNA-binding region of the histone heterodimer, preventing it from spontaneous association with DNA. Our analysis also revealed a novel site in CENP-A that distinguishes it from histone H3 in its ability to bind HJURP. These findings provide key information for specific recognition of CENP-A and mechanistic insights into the process of centromeric chromatin assembly.

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