Developmental and housekeeping transcriptional programs in Drosophila require distinct chromatin remodelers

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Neutron powder diffraction in molecule-based magnetic materials: Long- and short-range magnetic order

Neutron scattering has long been the ultimate technique of choice for defining the structures and excitations in magnetically ordered solids. Hence, it is surprising that neutron diffraction has not played a larger part in the rapidly growing field of molecule-based magnets. There are several reasons for this: large-volume unit-cells, frequency of low symmetry, containing a relatively low concentration of magnetic centers meaning that the magnetic contribution is a small fraction of the total scattering while the need to deuterate the organic ligands limits the available molecules. Nevertheless, it is possible to get information about short- and long-range ordering and this brief review summarizes the recent work on contrasting molecular magnetic materials: the weakly ferromagnetic Mn(II) organo-phosphonates; the bimetallic oxalato- and dithio-oxalato-honeycomb layer ferro- and ferrimagnets and a prototype for π-d ferrimagnetism in ion-radical salts.     

Expression of NYV1 encoding the negative regulator of Pmc1 is repressed by two transcriptional repressors,Nrg1 and Mig1

ESCRT components function to form multivesicular bodies for sorting of proteins destined to the yeast vacuole. The calcium hypersensitivity of ESCRT mutants is mainly due to repressed expression of PMR1 through the Rim101/Nrg1 pathway in budding yeast. Here, we show that overexpression of PMC1 and its negative regulator gene NYV1 suppresses and increases calcium hypersensitivity of ESCRT mutants, respectively. Consistently, deletion of NYV1 suppresses their calcium hypersensitivity. Expression of NYV1 is dramatically reduced in ESCRT mutants. Promoter analysis demonstrates that both Nrg1 and Mig1 repress NYV1 expression. Deletion of ESCRTs increases Nrg1 binding, but not Mig1-binding, to the NYV1 promoter. Deletion of MIG1 increases calcium sensitivity of ESCRT mutants due to derepression of NYV1 expression.     

Development of a repressible mycobacterial promoter system based on two transcriptional repressors

Tightly regulated gene expression systems represent invaluable tools for studying gene function and for the validation of drug targets in bacteria. While several regulated bacterial promoters have been characterized, few of them have been successfully used in mycobacteria. In this article we describe the development of a novel repressible promoter system effective in both fast- and slow-growing mycobacteria based on two chromosomally encoded repressors, dependent on tetracycline (TetR) and pristinamycin (Pip), respectively. This uniqueness results in high versatility and stringency. Using this method we were able to obtain an ftsZ conditional mutant in Mycobacterium smegmatis and a fadD32 conditional mutant in Mycobacterium tuberculosis, confirming their essentiality for bacterial growth in vitro. This repressible promoter system could also be exploited to regulate gene expression during M. tuberculosis intracellular growth.