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In photosynthetic eukaryotes, thousands of proteins are translated in the cytosol and imported into the chloroplast through the concerted action of two translocons-termed TOC and TIC-located in the outer and inner membranes of the chloroplast envelope, respectively. The degree to which the molecular composition of the TOC and TIC complexes is conserved over phylogenetic distances has remained controversial. Here, we combine transcriptomic, biochemical, and genetic tools in the green alga Chlamydomonas (Chlamydomonas reinhardtii) to demonstrate that, despite a lack of evident sequence conservation for some of its components, the algal TIC complex mirrors the molecular composition of a TIC complex from Arabidopsis thaliana. The Chlamydomonas TIC complex contains three nuclear-encoded subunits, Tic20, Tic56, and Tic100, and one chloroplast-encoded subunit, Tic214, and interacts with the TOC complex, as well as with several uncharacterized proteins to form a stable supercomplex (TIC-TOC), indicating that protein import across both envelope membranes is mechanistically coupled. Expression of the nuclear and chloroplast genes encoding both known and uncharacterized TIC-TOC components is highly coordinated, suggesting that a mechanism for regulating its biogenesis across compartmental boundaries must exist. Conditional repression of Tic214, the only chloroplast-encoded subunit in the TIC-TOC complex, impairs the import of chloroplast proteins with essential roles in chloroplast ribosome biogenesis and protein folding and induces a pleiotropic stress response, including several proteins involved in the chloroplast unfolded protein response. These findings underscore the functional importance of the TIC-TOC supercomplex in maintaining chloroplast proteostasis.

The primary event in mammalian sexual development is the differentiation of the bipotential gonads into either testes or ovaries. Our understanding of the molecular pathways specifying gonadal differentiation is still incomplete. To identify the initial molecular changes accompanying gonadal differentiation in mice, we have performed a large-scale transcriptional analysis of XX and XY Sfl-positive gonadal cells during sex determination. In both male and female genital ridges, a robust genetic program is initiated pre-dating the first morphological changes of the differentiating gonads. Between E10.5 and E13.5, 2306 genes were expressed in a sex-specific manner in the somatic compartment of the gonads; 1223 were overexpressed in XX embryos and 1083 in XY embryos. Although sexually dimorphic genes were scattered throughout the mouse genome, we identified chromosomal regions hosting clusters of genes displaying similar expression profiles. The cyclin-dependent kinase inhibitors Cdknla and Cdknlc are overexpressed in XX gonads at E11.5 and E12.5, suggesting that the increased proliferation of XY gonads relative to XX gonads may result from the overexpression of cell cycle inhibitors in the developing ovaries. These studies define the major characteristics of testicular and ovarian transcriptional programs and reveal the richness of signaling processes in differentiation of the bipotential gonads into testes and ovaries. Keywords: Sfl; Gonads; Sex determination; Ovary; Testis; Gene regulation

Recent developments in laser-based fluorescence microscopy have enabled the observation of ligand binding to a single molecule. Such ligand-binding events have been simulated for the nicotinic acetylcholine receptor and compared with single channel eventus under pulsed agonist conditions. This could provide new information relating to the role of ligand binding in the stabilization of conformational changes.

The lability of mononuclear octahedral complex as compared to the dinuclear triple-helical complex of cobalt has been investigated. Electrospray mass spectroscopy (ESMS) was utilized to study the ligand exchange in the triple-helical complex and establishes the formation pathway of this complex. The slow racemization of the dinuclear triple complex is due to the slow dissociative mechanism of cobalt from the complex. Its inertness arises from the rigidity of the ligand which results in a tight pitch.

The segmental ligand 2-(6-(N,N-diethylcarbamoyl)pyridin-2-yl)-1,1'-dimethyl-5,5'-methylene-2'-(5- methylpyridin-2-yl)bis(1H-benzimidazole)(L2) reacts with stoichiometric quantities of Ln(III) and Zn(II) in acetonitrile to produce quantitatively and selectively the heterodinuclear triple-helical complexes (LnZn(L2)3)5+ under thermodynamic control. The three ligands L2 are wrapped around a pseudo-C3 axis passing through the metal ions. Zn(II) lies on the distorted pseudooctahedral capping coordination site defined by three bidentate binding units while Eu(III) occupies the resulting 'facial' pseudotricapped trigonal prismatic site created by the three remaining tridentate units.

Reaction of a segmental bidentate-tridentate ligand L1 with Fe(I), Zn(II) and Co(II) in acetonitrile produces mononuclear head-to-head complexes (ML1(2))2+. Various spectroscopic and spectrophotometric studies show that the complex reacts with a second metal ion to produce (M2L1(2))4+ and exhibits high stability for M = Zn(II) and Co(II). Reaction between (FeL1(2))2+ and Ag(I) form self-assembled heterodinuclear double-helical complexes (FeAgL1(2))3+ and a trileptic ligand L2 reacts with Fe(II) and Ag(I) producing a self-assembled D2-symmetrical heterodinuclear complex (FeAg2L2(2))4+.

Co(II) perchlorate reacts with bis(5-(1-methyl-2-(X'-methyl-2'-pyridyl)benzimidazolyl))methane in acetonitrile to yield self-assembled dinuclear triple-helical complexes. X-ray studies reveal the presence of dinuclear triple helical cations. The coordination spheres around the high-spin Co(II) ions exist as flattened octahedra along the C(3) axis. Steric repulsions of methyl groups in the 6-position of pyridine rings distort the coordination sphere and increase Co-N(py) bond distances. Spectroscopic and spectrophotometric studies suggest a cooperative self-assembly process for the formation of pseudo-D(3) triple-helical structures.

Abstract Background The high-density oligonucleotide microarray (GeneChip) is an important tool for molecular biological research aiming at large-scale detection of small nucleotide polymorphisms in DNA and genome-wide analysis of mRNA concentrations. Local array data management solutions are instrumental for efficient processing of the results and for subsequent uploading of data and annotations to a global certified data repository at the EBI (ArrayExpress) or the NCBI (GeneOmnibus). Description To facilitate and accelerate annotation of high-throughput expression profiling experiments, the Microarray Information Management and Annotation System (MIMAS) was developed. The system is fully compliant with the Minimal Information About a Microarray Experiment (MIAME) convention. MIMAS provides life scientists with a highly flexible and focused GeneChip data storage and annotation platform essential for subsequent analysis and interpretation of experimental results with clustering and mining tools. The system software can be downloaded for academic use upon request. Conclusion MIMAS implements a novel concept for nation-wide GeneChip data management whereby a network of facilities is centered on one data node directly connected to the European certified public microarray data repository located at the EBI. The solution proposed may serve as a prototype approach to array data management between research institutes organized in a consortium.

The function of the nuclear receptor Rev-erbα (Nr1d1) in the brain is, apart from its role in the circadian clock mechanism, unknown. Therefore, we compared gene expression profiles in the brain between wild-type and Rev-erbα knock-out (KO) animals. We identified fatty acid binding protein 7 (Fabp7, Blbp) as a direct target of repression by REV-ERBα. Loss of Rev-erbα manifested in memory and mood related behavioral phenotypes and led to overexpression of Fabp7 in various brain areas including the subgranular zone (SGZ) of the hippocampus, where neuronal progenitor cells (NPCs) can initiate adult neurogenesis. We found increased proliferation of hippocampal neurons and loss of its diurnal pattern in Rev-erbα KO mice. In vitro, proliferation and migration of glioblastoma cells were affected by manipulating either Fabp7 expression or REV-ERBα activity. These results suggest an important role of Rev-erbα and Fabp7 in adult neurogenesis, which may open new avenues for treatment of gliomas as well as neurological diseases such as depression and Alzheimer. [ABSTRACT FROM AUTHOR]