Common gardens in teosintes reveal the establishment of a syndrome of adaptation to altitude.

In plants, local adaptation across species range is frequent. Yet, much has to be discovered on its environmental drivers, the underlying functional traits and their molecular determinants. Genome scans are popular to uncover outlier loci potentially involved in the genetic architecture of local adaptation, however links between outliers and phenotypic variation are rarely addressed.

Assessing the Response of Small RNA Populations to Allopolyploidy Using Resynthesized Brassica napus Allotetraploids.

Allopolyploidy, combining interspecific hybridization with whole genome duplication, has had significant impact on plant evolution. Its evolutionary success is related to the rapid and profound genome reorganizations that allow neoallopolyploids to form and adapt. Nevertheless, how neoallopolyploid genomes adapt to regulate their expression remains poorly understood.

Vernalization treatment induces site-specific DNA hypermethylation at the VERNALIZATION-A1 (VRN-A1) locus in hexaploid winter wheat.

Background: Certain temperate species require prolonged exposure to low temperature to initiate transition from vegetative growth to flowering, a process known as vernalization. In wheat, winter cultivars require vernalization to initiate flowering, making vernalization requirement a trait of key importance in wheat agronomy. The genetic bases of vernalization response have been largely studied in wheat, leading to the characterization of a regulation pathway that involves the key gene VERNALIZATION1 (VRN1).

Non-Newtonian viscosity of Escherichia coli suspensions.

The viscosity of an active suspension of E. coli bacteria is determined experimentally as a function of the shear rate using a Y-shaped microfluidic channel. From the relative suspension viscosity, we identify rheological thickening and thinning regimes as well as situations at low shear rate where the viscosity of the bacteria suspension can be lower than the viscosity of the suspending fluid.

Allopolyploidy has a moderate impact on restructuring at three contrasting transposable element insertion sites in resynthesized Brassica napus allotetraploids.

The role played by whole-genome duplication (WGD) in evolution and adaptation is particularly well illustrated in allopolyploids, where WGD is concomitant with interspecific hybridization. This 'Genome Shock', usually accompanied by structural and functional modifications, has been associated with the activation of transposable elements (TEs). However, the impact of allopolyploidy on TEs has been studied in only a few polyploid species, and not in Brassica, which has been marked by recurrent polyploidy events.

Maize genetic diversity and association mapping using transposable element insertion polymorphisms.

Transposable elements are the major component of the maize genome and presumably highly polymorphic yet they have not been used in population genetics and association analyses. Using the Transposon Display method, we isolated and converted into PCR-based markers 33 Miniature Inverted Repeat Transposable Elements (MITE) polymorphic insertions. These polymorphisms were genotyped on a population-based sample of 26 American landraces for a total of 322 plants.

Design and development of a field-deployable single-molecule detector (SMD) for the analysis of molecular markers.

Single-molecule detection (SMD) has demonstrated some attractive benefits for many types of biomolecular analyses including enhanced processing speed by eliminating processing steps, elimination of ensemble averaging and single-molecule sensitivity. However, it's wide spread use has been hampered by the complex instrumentation required for its implementation when using fluorescence as the readout modality. We report herein a simple and compact fluorescence single-molecule instrument that is straightforward to operate and consisted of fiber optics directly coupled to a microfluidic device.

Enhanced diffusion due to active swimmers at a solid surface.

We consider two systems of active swimmers moving close to a solid surface, one being a living population of wild-type E. coli and the other being an assembly of self-propelled Au-Pt rods. In both situations, we have identified two different types of motion at the surface and evaluated the fraction of the population that displayed ballistic trajectories (active swimmers) with respect to those showing randomlike behavior.

Contrasted patterns of selection since maize domestication on duplicated genes encoding a starch pathway enzyme.

Maize domestication from teosinte (Zea mays ssp. parviglumis) was accompanied by an increase of kernel size in landraces. Subsequent breeding has led to a diversification of kernel size and starch content among major groups of inbred lines.

Inhibiting Crm1 causes the formation of excess acentriolar spindle poles containing NuMA and B23, but does not affect centrosome numbers.

Background: B23/nucleophosmin is present on spindle poles at metaphase. Migration of B23 to the poles is under the control of exportin Crm1. B23 at the centrosome plays a role in the control centrosome duplication.

Epistatic interactions between Opaque2 transcriptional activator and its target gene CyPPDK1 control kernel trait variation in maize.

Association genetics is a powerful method to track gene polymorphisms responsible for phenotypic variation, since it takes advantage of existing collections and historical recombination to study the correlation between large genetic diversity and phenotypic variation. We used a collection of 375 maize (Zea mays ssp. mays) inbred lines representative of tropical, American, and European diversity, previously characterized for genome-wide neutral markers and population structure, to investigate the roles of two functionally related candidate genes, Opaque2 and CyPPDK1, on kernel quality traits.

Structural and functional effects of hydrostatic pressure on centrosomes from vertebrate cells.

In an attempt to better understand the role of centrioles in vertebrate centrosomes, hydrostatic pressure was applied to isolated centrosomes as a means to disassemble centriole microtubules. Treatments of the centrosomes were monitored by analyzing their protein composition, ultrastructure, their ability to nucleate microtubules from pure tubulin, and their capability to induce parthenogenetic development of Xenopus eggs. Moderate hydrostatic pressure (95 MPa) already affected the organization of centriole microtubules in isolated centrosomes, and also impaired microtubule nucleation.

Establishment of a human malignant fibrous histiocytoma cell line, COMA. Characterization By conventional cytogenetics, comparative genomic hybridization, and multiplex fluorescence In situ hybridization.

The human COMA cell line has been established from a storiform pleomorphic malignant fibrous histiocytoma (MFH). As expected for this tumor type, a very complex karyotype was observed after R-banding analysis. An extensive analysis by 24-color painting, comparative genomic hybridization (CGH), and fluorescence in situ hybridization (FISH) was performed.

The nucleolar phosphoprotein B23 redistributes in part to the spindle poles during mitosis.

B23 is a major phosphoprotein in the interphasic nucleolus where it is involved in the assembly of pre-ribosomes. Using several cultured animal cells, we report that, in addition to the known redistribution of the protein during mitosis, B23 also becomes associated with mitotic spindle poles starting from early prometaphase onwards. Colocalization of B23 with the protein NuMA (Nuclear Mitotic Apparatus protein) was studied in mitotic cells and taxol-arrested cells.

Aminopeptidase B: a processing enzyme secreted and associated with the plasma membrane of rat pheochromocytoma (PC12) cells.

Aminopeptidase B (Ap-B) is a Zn2+-dependent exopeptidase which selectively removes Arg and/or Lys residues from the N terminus of several peptide substrates. Isolated and characterized from rat testes, this ubiquitous enzyme may participate in the final stages of precursor processing mechanisms. To test this hypothesis, we have investigated the secretion and subcellular localization of this enzyme in a rat cell line of pheochromocytoma (PC12 cells).

Interaction of a Golgi-associated kinesin-like protein with Rab6.

Rab guanosine triphosphatases regulate vesicular transport and membrane traffic within eukaryotic cells. Here, a kinesin-like protein that interacts with guanosine triphosphate (GTP)-bound forms of Rab6 was identified. This protein, termed Rabkinesin-6, was localized to the Golgi apparatus and shown to play a role in the dynamics of this organelle.

Entry and distribution of fluorescent antiproliferative heparin derivatives into rat vascular smooth muscle cells: comparison between heparin-sensitive and heparin-resistant cultures.

We studied the binding and entry of fluorescein (FITC)-labeled heparin derivatives into rat aortic smooth muscle cells (SMC) by confocal microscopy. FITC-labeled heparin fractions or FITC-labeled SR 80037A, a potent antiproliferative heparin derivative (Bârzu et al., Eur.

Defined glycosaminoglycan motifs have opposite effects on neuronal polarity in vitro.

We previously reported that heparan sulfates enhance axonal outgrowth and inhibit dendrite elongation, whereas dermatan sulfates favor the development of both axons and dendrites. The present study focuses on the activity of small synthetic heparan or dermatan sulfate-like compounds. We found three heparan sulfate-like and three dermatan sulfate-like sugars that mimic the morphological effects of the high-molecular-weight natural glycosaminoglycans.

Production and characterization of polyclonal anti-idiotypic anti-TRH antibodies: application to the study of pituitary TRH receptor.

cDNA encoding the thyrotropin-releasing hormone receptor (TRH-R) was recently cloned in rat pituitary prolactin cells and in mouse thyrotropes. The molecular weights of the protein sequences obtained are 46.6 and 44.

Specific responses of axons and dendrites to cytoskeleton perturbations: an in vitro study.

Several factors can influence the development of axons and dendrites in vitro. Some of these factors modify the adhesion of neurons to their substratum. We have previously shown that the threshold of neuron-substratum adhesion necessary for initiation and elongation of dendrites is higher than that required for axonal growth.

In vitro control of neuronal polarity by glycosaminoglycans.

We have studied the effects of proteoglycans (PGs) and glycosaminoglycans (GAGs) on the growth and morphology of neurons in culture. PGs from glial cells or Engelbreth-Holm-Swarm tumor cells (EHS), pure bovine kidney heparan sulfate (HS), shark cartilage type C chondroïtin sulfate (CSc) and bovine mucosa dermatan sulfate (DS) added to embryonic rat neurons strongly enhanced total neurite growth after 48 h in vitro. No trophic effects were seen when PGs treated with a mixture of glycanases were used.

In vitro regulation of neuronal morphogenesis and polarity by astrocyte-derived factors.

Mesencephalic neurons were cultured from 2 to 5 days in mesencephalic (CM Gmes) or striatal (CM Gstr) astrocyte conditioned media or in the soluble (S100) and insoluble (P100) fractions prepared from these media by ultracentrifugation. CM Gmes as well as all soluble fractions induced dendritic and axonal elongation, whereas CM Gstr and the insoluble fractions promoted axonal growth only. The study of the shape of the neuronal cell bodies and the measurement of their adhesion to the substratum revealed that axons elongated under low adhesion conditions, but that dendrite growth was highly dependent upon adhesion and spreading of the neuronal soma.