Combined linkage and linkage disequilibrium QTL mapping in multiple families of maize (Zea mays L.) line crosses highlights complementarities between models based on parental haplotype and single locus polymorphism.

Advancements in genotyping are rapidly decreasing marker costs and increasing marker density. This opens new possibilities for mapping quantitative trait loci (QTL), in particular by combining linkage disequilibrium information and linkage analysis (LDLA). In this study, we compared different approaches to detect QTL for four traits of agronomical importance in two large multi-parental datasets of maize (Zea mays L.

Chemical microscopy of biological samples by dynamic mode secondary ion mass spectrometry.

3D chemical microscopy is one of the emerging applications of secondary ion mass spectrometry (SIMS) in biology. Tissues, cells, extracellular matrices, and polymer films can be imaged at present with a lateral resolution of 50 nm and depth resolution of 1 nm using the latest generation of CAMECA magnetic sector NanoSIMS 50 or with a lower lateral resolution (above 100 nm) using IMS 4f Cameca SIMS equipped with cold stage. Dynamic mode SIMS analysis is performed in ultrahigh vacuum and thus requires specific and careful preparation of biological samples aimed at preserving and minimizing destruction of the original structural and chemical properties of the samples.

Relative sensitivity factors of inorganic cations in frozen-hydrated standards in secondary ion MS analysis.

We describe the measurement, at 100 K, of the SIMS relative sensitivity factors (RSFs) of the main physiological cations Na+, K+, Mg2+, and Ca2+ in frozen-hydrated (F-H) ionic solutions. Freezing was performed by either plunge freezing or high-pressure freezing. We also report the measurement of the RSFs in flax fibers, which are a model for ions in the plant cell wall, and in F-H ionic samples, which are a model for ions in the vacuole.

Dynamic-SIMS imaging and quantification of inorganic ions in frozen-hydrated plant samples.

We present here SIMS images of the distribution of inorganic cations (Na, K, Mg and Ca) in frozen-hydrated samples of three plant species, ivy, camomile, and flax. The samples were cryofixed using fast plunge-freezing. Stigmatic images were obtained, at 100 K, under dynamic SIMS conditions by fast atom bombarding (FAB).

Appraisal of SIMS applicability to boron studies in plants.

In the search for a new methodological approach applicable to the determination of the still poorly known primary role of boron in plant physiology, we have undertaken to appraise the potential of the SIMS method for the analytical imaging of the boron isotopes, (10)B and (11)B, at physiological concentrations in plants. With our own, CAMECA IMS4F SIMS ion analyser, and using O(2)(+) as primary ions for the detection of B(+) (plus (12)C(+) and (40)Ca(+)) secondary ions, we have been able to map quantitatively the two boron isotopes in control and boron-enriched plants, to evaluate boron concentrations at the level of individual cells and to determine boron isotopic ratios. This provides the opportunity to carry out the simultaneous labeling and imaging of boron, using enrichment with the stable isotopes, (10)B and (11)B.