A Strategy for Polar Crystals with Dipolar Heterohelicenes

Polar crystals have attracted interest for the applications to polar materials with piezo- and pyroelectricity, and second harmonic generation. Despite their potential utility for flexible polar materials, a strategy for ordering polar helicenes has remained elusive. Here, we demonstrate the creation of polar crystals with unsymmetrically substituted aza[5]helicenes tuned by substituents. The unsymmetric aza[5]helicenes have been prepared through regioselective mono-protiodesilylations. We disclose that triisopropylsilyl-substituted derivatives show 1D chain columnar packings. In particular, enantiopure crystals showed spontaneous polarization. Optical and single-crystal X-ray diffraction experiments with other derivatives, as well as theoretical calculations, revealed that the presence of triisopropylsilyl or electron-withdrawing aryl substituents is essential for forming the 1D chain columnar structure. Hirshfeld surface analyses further showed that CH-π interactions between 1D chain columns regulate the polar assembly. Finally, we determined the polarizability of the nitro derivative by ab initio calculation to be 4.53 μC/cm². This value corroborates the first example of a spontaneously polar crystal of helicenes. We believe that this study will contribute to the development of polar materials from organic molecules

Acquisition of the Ability To Assimilate Mannitol by Saccharomyces cerevisiae through Dysfunction of the General Corepressor Tup1-Cyc8.

Saccharomyces cerevisiae normally cannot assimilate mannitol, a promising brown macroalgal carbon source for bioethanol production. The molecular basis of this inability remains unknown. We found that cells capable of assimilating mannitol arose spontaneously from wild-type S. cerevisiae during prolonged culture in mannitol-containing medium. Based on microarray data, complementation analysis, and cell growth data, we demonstrated that acquisition of mannitol-assimilating ability was due to spontaneous mutations in the genes encoding Tup1 or Cyc8, which constitute a general corepressor complex that regulates many kinds of genes. We also showed that an S. cerevisiae strain carrying a mutant allele of CYC8 exhibited superior salt tolerance relative to other ethanologenic microorganisms; this characteristic would be highly beneficial for the production of bioethanol from marine biomass. Thus, we succeeded in conferring the ability to assimilate mannitol on S. cerevisiae through dysfunction of Tup1-Cyc8, facilitating production of ethanol from mannitol

HIRA, a conserved histone chaperone, plays an essential role in low-dose stress response via transcriptional stimulation in fission yeast.

Cells that have been pre-exposed to mild stress (priming stress) acquire transient resistance to subsequent severe stress even under different combinations of stresses. This phenomenon is called cross-tolerance. Although it has been reported that cross-tolerance occurs in many organisms, the molecular basis is not clear yet. Here, we identified slm9(+) as a responsible gene for the cross-tolerance in the fission yeast Schizosaccharomyces pombe. Slm9 is a homolog of mammalian HIRA histone chaperone. HIRA forms a conserved complex and gene disruption of other HIRA complex components, Hip1, Hip3, and Hip4, also yielded a cross-tolerance-defective phenotype, indicating that the fission yeast HIRA is involved in the cross-tolerance as a complex. We also revealed that Slm9 was recruited to the stress-responsive gene loci upon stress treatment in an Atf1-dependent manner. The expression of stress-responsive genes under stress conditions was compromised in HIRA disruptants. Consistent with this, Pol II recruitment and nucleosome eviction at these gene loci were impaired in slm9Δ cells. Furthermore, we found that the priming stress enhanced the expression of stress-responsive genes in wild-type cells that were exposed to the severe stress. These observations suggest that HIRA functions in stress response through transcriptional regulation

Restraint stress up-regulates expression of zinc transporter Zip14 mRNA in mouse liver

The zinc concentration in the liver was significantly higher in mice at 12 h after the onset of restraint stress than that without stress. The IL-6 protein level in the serum was transiently elevated at 3 h after the onset of restraint stress, and the IL-6-responsive zinc transporter Zip14 mRNA in the liver was expressed markedly at 6 h. These results suggest that Zip14 plays a major role in the mechanism responsible for accumulation of zinc in the liver under restraint stress