On the cover
A confocal image of a live zebrafish embryo shows the large vacuoles (labeled by LAMP1, red) that form in notochord cells (labeled with the membrane marker GFP-CaaX, green). Ellis et al. reveal that notochord vacuoles are lysosome-related organelles that promote embryonic axis elongation and spine morphogenesis.
Image © 2013 Ellis et al.
See page 667.
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Sequential actin-based pushing forces drive meiosis I chromosome migration and symmetry breaking in oocytes
Meiosis I chromosome migration is biphasic, with an early, slow phase requiring Fmn2 and a later, fast and highly directed phase requiring the Arp2/3 complex.
Both endonucleolytic and exonucleolytic cleavage mediate ITS1 removal during human ribosomal RNA processing
Human ribosomal RNA processing is initiated by endonuclease cleavage and followed by 3′ to 5′ exonucleolytic processing by RRP6 and the exosome.
Promoter- and RNA polymerase II–dependent hsp-16 gene association with nuclear pores in Caenorhabditis elegans
The hsp-16.2 promoter is sufficient for recruitment of hsp-16.2 to nuclear pore complexes in a manner dependent on RNA pol II and ENY-2, but not on full-length mRNA production.
Both LMNB1 depletion and overexpression inhibit proliferation, but only LMNB1 overexpression induces senescence.
Arp2/3 complex ATP hydrolysis promotes lamellipodial actin network disassembly but is dispensable for assembly
ATP hydrolysis on both Arp2 and Arp3 influences dissociation of the Arp2/3 complex from the lamellipodial actin network but is not strictly necessary for network disassembly.
The WD40 protein Morg1 facilitates Par6–aPKC binding to Crb3 for apical identity in epithelial cells
Par6–aPKC recruitment to the premature apical membrane through Morg1 interaction with Par6 is required for definition of apical identity of epithelial cells.
The tail-anchored protein PEX26 is recognized by PEX19 in the cytosol and targeted to PEX3 on peroxisomes in a manner independent of TRC40-mediated targeting to the ER.
The zebrafish notochord vacuole, which has long been known to be important for vertebrate development but poorly classified at a cell biological level, is identified as a specialized lysosome-related organelle that is necessary both early, for embryonic axis elongation, and late, for spine morphogenesis.