Roles Of Hof1p, Bni1p, Bnr1p, And Myo1p In Cytokinesis In Saccharomyces Cerevisiae

Cytokinesis in Saccharomyces cerevisiae occurs by the concerted action of the actomyosin system and septum formation. Here we report on the roles of HOF1,BNI1, and BNR1 in cytokinesis, focusing on Hof1p. Deletion of HOF1 causes a temperature-sensitive defect in septum formation. A Hof1p ring forms on the mother side of the bud neck in G2/M, followed by the formation of a daughter-side ring. Around telophase, Hof1p is phosphorylated and the double rings merge into a single ring that contracts slightly and may colocalize with the actomyosin structure. Upon septum formation, Hof1p splits into two rings, disappearing upon cell separation. Hof1p localization is dependent on septins but not Myo1p. Synthetic lethality suggests that Bni1p and Myo1p belong to one functional pathway, whereas Hof1p and Bnr1p belong to another. These results suggest that Hof1p may function as an adapter linking the primary septum synthesis machinery to the actomyosin system. The formation of the actomyosin ring is not affected by bni1Δ, hof1Δ, orbnr1Δ. However, Myo1p contraction is affected bybni1Δ but not by hof1Δ orbnr1Δ. In bni1Δ cells that lack the actomyosin contraction, septum formation is often slow and asymmetric, suggesting that actomyosin contraction may provide directionality for efficient septum formation

Ethical Challenges of the Industry: Are Graduates Prepared?

Hospitality graduates often enter their first jobs unaware of the difficult ethical dilemmas they will face. By having ethics teaching in a curriculum, the authors of this article believe that the perceptions of ethics of senior hospitality students at Northern Arizona University were comparable to those of operating industry managers

Immobile Myosin-II Plays A Scaffolding Role During Cytokinesis In Budding Yeast

Core components of cytokinesis are conserved from yeast to human, but how these components are assembled into a robust machine that drives cytokinesis remains poorly understood. In this paper, we show by fluorescence recovery after photobleaching analysis that Myo1, the sole myosin-II in budding yeast, was mobile at the division site before anaphase and became immobilized shortly before cytokinesis. This immobility was independent of actin filaments or the motor domain of Myo1 but required a small region in the Myo1 tail that is thought to be involved in higher-order assembly. As expected, proteins involved in actin ring assembly (tropomyosin and formin) and membrane trafficking (myosin-V and exocyst) were dynamic during cytokinesis. Strikingly, proteins involved in septum formation (the chitin synthase Chs2) and/or its coordination with the actomyosin ring (essential light chain, IQGAP, F-BAR, etc.) displayed Myo1-dependent immobility during cytokinesis, suggesting that Myo1 plays a scaffolding role in the assembly of a cytokinesis machine

Mutations In SID2, A Novel Gene In Saccharomyces Cerevisiae, Cause Synthetic Lethality With Sic1 Deletion And May Cause A Defect During S Phase

SIC1 encodes a nonessential B-type cyclin/CDK inhibitor that functions at the G1/S transition and the exit from mitosis. To understand more completely the regulation of these transitions, Mutations causing synthetic lethality with sic1 Delta were isolated. In this screen, we identified a novel gene, SID2, which encodes an essential protein that appear., to be required for DNA replication or repair. sid2-1 sic1 Delta strains and sid2-21 temperature-sensitive strains arrest preanaphase as large-budded cells with a single nucleus, a short spindle, and an similar to 2C DNA content. RAD9, which is necessary for the DNA damage checkpoint, is required for the preanaphase arrest of sid2-1 sic1 Delta cells. Analysis of chromosomes in mutant sid2-21 cells by field inversion gel clectropiioresis suggests the presence of replication forks and bubbles at the arrest. Deleting the two S phase cyclins, CLB5 and CLB6, substantially suppresses the sid2-1 sir1 Delta inviability, while stabilizing Clb5 protein exacerbates the defects of sid2-1 sic1 Delta, cells. In synchronized sid2-1 mutant strains, the onset of replication appears normal, but completion of DNA synthesis is delayed. sid2-1 mutants are sensitive to hydroxytirea indicating that sid2-1 cells may suffer DNA damage that, when combined with additional insult, leads to a decrease in viability. Consistent with this hypothesis, sid2-1 rad9 cells are dead or very slow growing even when SIC1 is expressed

Print awareness of adult illiterates: a comparison with young pre-readers and low-educated adult readers

In this study the print awareness of 25 unschooled adult illiterates in the Netherlands was compared with that of 24 pre-reading children and of 23 low-educated literate adults with approximately four years of primary schooling. The illiterates were interviewed about their experiences with writing and all participants completed six assessments of print awareness in the language they preferred (first or second language). The outcomes revealed that the three groups did not differ in distinguishing conventional written signs from other visual signs, that both groups of non-readers differed significantly from low educated readers but not from each other in knowledge of logos, inscriptions and knowledge of the written register, while the adult illiterates performed significantly better than the children on grapheme knowledge. Adult illiterates in literate societies seem to be well informed about the uses and functions of written language and about what writing looks like, but like young children they are not good at reading environmental print out of context and in explaining what exactly is represented in writing. The variation in reactions within the group of illiterate adults could be related to existing models of emergent literacy. Implications for adult literacy education are discussed

Bet Hedging in Yeast by Heterogeneous, Age-Correlated Expression of a Stress Protectant

A new experimental approach reveals a bet-hedging strategy in unstressed, clonal yeast cells, whereby they adopt a range of growth states that correlate with expression of a trehalose-synthesis regulator and predict resistance to future stress

Bayesian Modeling of the Yeast SH3 Domain Interactome Predicts Spatiotemporal Dynamics of Endocytosis Proteins

A genome-scale specificity and interaction map for yeast SH3 domain-containing proteins reveal how family members show selective binding to target proteins and predicts the dynamic localization of new candidate endocytosis proteins