A Comparison of Landraces vs. Modern Varieties of Lettuce in Organic Farming During the Winter in the Mediterranean Area: An Approach Considering the Viewpoints of Breeders, Consumers, and Farmers.

The interest of farmers in growing lettuce landraces is increasing, as landrace varieties prove particularly appealing to consumers striving to purchase natural, local, and high-quality produce. Although high genetic diversity exists in the landrace gene pool, this has scarcely been studied, thus hindering landrace utilization in agriculture. In this study, we analyzed the genetic diversity and the agronomic and quality traits of lettuce landraces in organic agrosystems, by characterizing 16 landraces and 16 modern varieties.

Uptake of inorganic carbon in the cyanobacterium Synechocystis PCC6803: physiological and genetic evidence for a high-affinity uptake system.

Synechocystis PCC6803 displays two inorganic carbon-uptake processes, a low-affinity one (apparent Km: 300-400 microM) functional in cells grown under standard or limiting inorganic carbon concentrations, and one with a higher affinity (60 +/- 12 microM), detected only in cells adapted to limiting inorganic carbon conditions. A mutational and screening procedure allowed the isolation of a mutant deficient in the high-affinity system, but only slightly impaired in its growth capacities. The mutated genomic region revealed two open reading frames (ORFs), possibly belonging to an operonic structure.

A protein is involved in accessibility of the inhibitor acetazolamide to the carbonic anhydrase(s) in the cyanobacterium Synechocystis PCC 6803.

A gene, zam (for resistance to acetazolamide), controlling resistance to the carbonic anhydrase inhibitor acetazolamide, is described. It has been cloned from a spontaneous mutant, AZAr-5b, isolated from the cyanobacterium Synechocystis PCC 6803, for its resistance to this drug (Bédu et al., Plant Physiol 93: 1312-1315, 1990).

Evolutionary comparisons of three enzymes of the threonine biosynthetic pathway among several microbial species.

As an approach in the study of the evolution of threonine biosynthetic pathways throughout various organisms, the sequences of three enzymes, namely homoserine dehydrogenase, homoserine kinase and threonine synthase, originating from six organisms, namely Escherichia coli, Bacillus subtilis, Corynebacterium glutamicum, Brevibacterium lactofermentum, Pseudomonas aeruginosa and Saccharomyces cerevisiae, were compared. As a general trend all three enzymatic activities were carried out by proteins sharing sequence relatedness (except for the homoserine kinase of P aeruginosa). Unexpectedly however, for each step one or two enzymes stood out of the main stream: i) for homoserine dehydrogenase, the yeast protein is atypically similar to the E coli enzyme; ii) for homoserine kinase, the P aeruginosa protein shares no similarity with any other species; and iii) for threonine synthase, the B subtilis protein is far distant from the enzymes of other species.

Sequence of a cluster of genes controlling synthesis and secretion of alkaline protease in Pseudomonas aeruginosa: relationships to other secretory pathways.

A genetic locus implicated in the synthesis and secretion of alkaline protease (APR) in Pseudomonas aeruginosa has been previously described [Guzzo et al., J. Bacteriol.

Cloning and expression in Escherichia coli of a phoA gene encoding a phosphate-irrepressible alkaline phosphatase of Zymomonas mobilis.

The Zymomonas mobilis phoA gene, encoding a phosphate-irrepressible alkaline phosphatase (ZAPase), was cloned and its expression was studied in phoA mutants of Escherichia coli. The ZAPase was recovered in the soluble fraction of E. coli.

Isolation, organization and expression of the Pseudomonas aeruginosa threonine genes.

Three genes from Pseudomonas aeruginosa involved in threonine biosynthesis, hom, thrB and thrC, encoding homoserine dehydrogenase (HDH), homoserine kinase (HK) and threonine synthase (TS), respectively, have been cloned and sequenced. The hom and thrc genes lie at the thr locus of the P. aeruginosa chromosome map (31 min) and are likely to be organized in a bicistronic operon.

Sequence analysis of the cellulase-encoding celY gene of Erwinia chrysanthemi: a possible case of interspecies gene transfer.

The Erwinia chrysanthemi (strain 3937) celY gene encoding the minor endoglucanase (EGY) was sequenced. The analysis of the upstream region allowed us to identify an in vivo active promoter recognized by the NtrA (sigma 54) holoenzyme. No similarity was found between the predicted amino acid (aa) sequences of EGY and either the Er.

Possible involvement of a L-delta 1-pyrroline-5-carboxylate (P5C) reductase in the synthesis of proline in Desulfovibrio desulfuricans Norway.

A L-delta 1-pyrroline-5-carboxylate reductase activity has been detected in crude extracts of Desulfovibrio desulfuricans Norway. This P5C reductase activity is also found when a 2.5 kb D.

Cloning and sequencing of the sacA gene: characterization of a sucrase from Zymomonas mobilis.

The Zymomonas mobilis gene (sacA) encoding a protein with sucrase activity has been cloned in Escherichia coli and its nucleotide sequence has been determined. Potential ribosome-binding site and promoter sequences were identified in the region upstream of the gene which were homologous to E. coli and Z.

A lipopeptide-encoding sequence upstream from the lysA gene of Pseudomonas aeruginosa.

An open reading frame (ORF) of 141 bp was observed upstream from the Pseudomonas aeruginosa lysA gene. The translation product of this ORF contains a signal peptide with a lipoprotein box, Ile-Ala-Ala-Cys, at the predicted signal peptidase cleavage site. The Escherichia coli phoA gene without its signal sequence was fused in frame to this ORF in a broad host-range plasmid.

Pseudomonas aeruginosa diaminopimelate decarboxylase: evolutionary relationship with other amino acid decarboxylases.

The lysA gene encodes meso-diaminopimelate (DAP) decarboxylase (E.C.4.

Homology between endoglucanase Z of Erwinia chrysanthemi and endoglucanases of Bacillus subtilis and alkalophilic Bacillus.

Nucleotide sequencing of the celZ gene encoding the extracellular endoglucanase Z of Erwinia chrysanthemi indicated the presence of an open reading frame encoding 428 amino acids. The mature protein appeared to be extended by a signal peptide of 43 amino acids; this sequence is unusually long and positively charged (+5). It was shown to function as a signal peptide by fusing it to a truncated phoA gene encoding Escherichia coli alkaline phosphatase.

Intramolecular recombination between partially homologous sequences in Escherichia coli and Xenopus laevis oocytes.

We describe a system to analyze the individual contribution of a single physical DNA end on intramolecular recombination between partially homologous sequences. We took advantage of this partial sequence divergence to measure the distance separating the DNA end from the final recombination event. We show that a single physical DNA end stimulates recombination when located in a region of homology.

Characterization of a new endoglucanase from Erwinia chrysanthemi.

The structural gene coding for a new endo-beta-1,4-glucanase of Erwinia chrysanthemi strain 3665, previously identified in a cosmid library, was subcloned into pUC18. The gene is expressed from a 1.9 X 10(3)-base-pair insert and its direction of transcription was determined.

Cloning in Escherichia coli of genes involved in the synthesis of proline and leucine in Desulfovibrio desulfuricans Norway.

A library of Desulfovibrio desulfuricans Norway genomic DNA was constructed in Escherichia coli with pBR322 as vector and plasmids able to complement the proA and leuB mutations of the host were screened. It was observed that all the plasmids studied were highly unstable, the insert DNA being rapidly lost under non-selective growth conditions. A 2.

Heterologous expression and regulation of the lysA genes of Pseudomonas aeruginosa and Escherichia coli.

The Pseudomonas aeruginosa lysA gene encoding diaminopimelate decarboxylase (DAP-decarboxylase) was cloned into a broad host range vector. This gene complemented a lys mutation at the lys-12 locus of P. aeruginosa and a lysA defect in Escherichia coli.

Processing of complex heteroduplexes in Escherichia coli and Cos-1 monkey cells.

Upon transformation into Escherichia coli or Cos-1 monkey cells, heteroduplex DNA made of two sequences containing many nucleotide mismatches yields a wide array of different molecules, some with a patchwork structure. Thus, complex heteroduplexes can be processed to generate many genetic variants.

Correction of complex heteroduplexes made of mouse H-2 gene sequences in Escherichia coli K-12.

We have prepared heteroduplexes between two plasmids that carry, in the same orientation, two H-2 cDNA inserts, 1.15 and 1.0 kilobase long, respectively.

Mouse genes coding for the major class I transplantation antigens: a mosaic structure might be related to the antigenic polymorphism.

The recent isolation, by recombinant DNA techniques, of cloned probes for mouse and human class I major transplantation antigens has initiated the molecular analysis of the corresponding genes. Mouse genes belong to a relatively large multigene family, whose members share extensive structural homologies. Sequence analyses suggest that some genes could have a mosaic structure.

DNA organisation in the chicken lysozyme gene region.

DNA sequences surrounding the lysozyme gene of the chicken have been cloned in several recombinants which define a region of 40 Kb. We have detected no other gene with a sequence related to that of the lysozyme gene, nor any gene expressed in the oviduct in these recombinants. This situation contrasts with that of the ovalbumin gene, in the vicinity of which lie two other genes of related structure expressed in the oviduct under hormonal control.

cDNA clone coding for part of a mouse H-2d major histocompatibility antigen.

mRNA coding for mouse major transplantation antigens of the d haplotype was partially purified, copied into double-stranded cDNA, and cloned in Escherichia coli. Clones were selected by their ability to hybridize specifically with mRNA coding for H-2K, D, or L antigens. One of these clones, pH-2d-1, carries a 1200-base-pair insert, comprising the noncoding region, including poly(A) at the 3' end and part of the coding region.