Nickel translocation via the phloem in the hyperaccumulator Noccaea caerulescens (Brassicaceae)

Plant and Soil - This study evaluated the effect of phloem translocation on Ni accumulation in the hyperaccumulator Noccaea caerulescens. The first experiment assessed the metal and organic...     

CFTR Protects against Mycobacterium abscessus Infection by Fine-Tuning Host Oxidative Defenses

1. Download high-res image (274KB)
2. Download full-size image

     

Interspecific recombinant congenic strains between C57BL/6 and mice of the Mus spretus species: a powerful tool to dissect genetic control of complex traits

Complex traits are under the genetic control of multiple genes, often with weak effects and strong epistatic interactions. We developed two new collections of mouse strains to improve genetic dissection of complex traits. They are derived from several backcrosses of the Mus spretus SEG/Pas or STF/Pas strains on the C57BL/6J background. Each of the 55 interspecific recombinant congenic strains (IRCSs) carries up to eight SEG/Pas chromosomal segments with an average size of 11.7 Mb, totalizing 1.37% of the genome. The complete series covers 39.7% of the SEG/Pas genome. As a complementary resource, six partial or complete interspecific consomic strains were developed and increased genome coverage to 45.6%. To evaluate the usefulness of these strains for QTL mapping, 16 IRCSs were compared with C57BL/6J for seven hematological parameters. Strain 66H, which carries three SEG/Pas chromosomal segments, had lower red blood cell volume and higher platelet count than C57BL/6J. Each chromosomal segment was isolated in a congenic strain to evaluate individual effects. Congenic strains were combined to assess epistasis. Our data show that both traits were controlled by several genes with complex epistatic interactions. IRCSs are therefore useful to unravel QTL with small effects and gene-by-gene interactions.     

Immunolocalization of Non-Symbiotic Hemoglobins During Somatic Embryogenesis in Chicory

Hemoglobins are ancient O₂-binding proteins, ubiquitously found in eukaryotes. They have been categorized as symbiotic, nonsymbiotic and truncated hemoglobins. We have investigated the cellular localization of nonsymbiotic hemoglobin proteins during somatic embryogenesis in Cichorium hybrid leaves (Cichorium intybus L. var. sativum × C. endivia var. latifolia) using immunolocalization technique. These proteins were detected during the two steps of culture: induction and expression. In leaves, hemoglobins colocalised with plastids, which were dispersed in the parietal cytoplasm as well as in the two guard cells of a stomata, but not in epidermis cells. Upon induction of embryogenesis, in the dark, this pattern disappeared. During the induction phase, where competent cells reinitiate the cell cycle and prepare for mitosis, hemoglobins appeared initially near chloroplasts, and then in the vicinity of vascular vessels especially in the phloem and in cells surrounding the xylem vessels. When leaf fragments were transferred to another medium for the expression phase, hemoglobins were observed in the majority of the leaf blade cells and in small young embryos but not in the older ones. Hemoglobins were also detected in other leaves cells or tissues all along the process. The role of these nonsymbiotic hemoglobins during somatic embryogenesis is discussed.Key Words: chicory, immunolocalization, nonsymbiotic hemoglobin, somatic embryogenesis     

Tuning of the enzyme ratio in a neutral redox convergent cascade: A key approach for an efficient one-pot/two-step biocatalytic whole-cell system

The efficiency of a versatile in vivo cascade involving a promiscuous alcohol dehydrogenase, obtained from a biodiversity search, and a Baeyer–Villiger monooxygenase was enhanced by the independent control of the production level of each enzyme to produce ε-caprolactone and 3,4-dihydrocoumarin. This goal was achieved by adjusting the copy number per cell of Escherichia coli plasmids. We started from the observation that this number generally correlates with the amount of produced enzyme and demonstrated that an in vivo multi-enzymatic system can be improved by the judicious choice of plasmid, the lower activity of the enzyme that drives the limiting step being counter-balanced by a higher concentration. Using a preconception-free approach to the choice of the plasmid type, we observed positive and negative synergetic effects, sometimes unexpected and depending on the enzyme and plasmid combinations. Experimental optimization of the culture conditions allowed us to obtain the complete conversion of cyclohexanol (16 mM) and 1-indanol (7.5 mM) at a 0.5-L scale. The yield for the conversion of cyclohexanol was 80% (0.7 g ε-caprolactone, for the productivity of 244 mg·L ⁻¹·h ⁻¹) and that for 1-indanol 60% (0.3 g 3,4-dihydrocoumarin, for the productivity of 140 mg·L ⁻¹·h ⁻¹).     

Diterpenes from the leaves of Croton zambesicus

Two new trachylobane- and one isopimarane-type diterpenoids: ent-18-hydroxy-trachyloban-3-one; ent-trachyloban-3-one; isopimara-7,15-dien-3beta-ol, were isolated from the leaves of Croton zambesicus, together with trans-phytol, beta-sitosterol, alpha-amyrin and stigmasterol. The structures were determined by extensive NMR techniques and X-ray analysis. The cytotoxicity of these compounds has been evaluated on cancer and non-cancer cell-lines.     

A two-dimensional proteome map of maize endosperm

We have established a proteome reference map for maize (Zea mays L.) endosperm by means of two-dimensional gel electrophoresis and protein identification with LC-MS/MS analysis. This investigation focussed on proteins in major spots in a 4-7 pI range and 10-100 kDa M(r) range. Among the 632 protein spots processed, 496 were identified by matching against the NCBInr and ZMtuc-tus databases (using the SEQUEST software). Forty-two per cent of the proteins were identified against maize sequences, 23% against rice sequences and 21% against Arabidopsis sequences. Identified proteins were not only cytoplasmic but also nuclear, mitochondrial or amyloplastic. Metabolic processes, protein destination, protein synthesis, cell rescue, defense, cell death and ageing are the most abundant functional categories, comprising almost half of the 632 proteins analyzed in our study. This proteome map constitutes a powerful tool for physiological studies and is the first step for investigating the maize endosperm development.