Date Palm DNA Mini-Preparation without Liquid Nitrogen

We have developed a new mini-procedure for isolation of total cellular DNA from date palm (Phoenix dactylifera L.). The procedure, which does not use liquid nitrogen, has proved useful due to temporary disruptions in supplies of liquid nitrogen that occur in countries where date palm trees are cultivated. DNA suitable for RFLP and PCR analyses is obtained.     

Characterization of rabbit lactate dehydrogenase-M and lactate dehydrogenase-H cDNAs. Control of lactate dehydrogenase expression in rabbit muscle

Two cDNA clones were isolated, one corresponding to the mRNA coding for lactate dehydrogenase-M (LDH-M), the other to the mRNA coding for lactate dehydrogenase-H (LDH-H). The cDNA inserts consist of the entire open reading frame for LDH-M and a partial sequence, from amino acid 117 to 332, for LDH-H. Using these two clones as probes we demonstrate that: (a) the abundance of mRNA is muscle-type dependent; (b) the ratio M/H subunit for protein and mRNA is well related in the muscles studied; and (c) the M + H mRNA level is not relative to the total LDH activity.     

Ribosomal DNA as a convenient probe to follow segregation and possible divergency from expected homozygosity after haploidization of an androgenetic process

Summary Restriction fragment length polymorphism of the wheat nuclear ribosomal DNA has been studied in several steps of a breeding scheme, including parental genotypes, F1 hybrid, F9 generation, and anther-derived doubled haploid lines obtained from F9. Ribosomal DNA represents a suitable molecular marker in following segregation and possible divergency from expected homozygosity after haploidization of an androgenetic process. It has been shown to undergo variations among the first cycle-doubled haploid lines in the relative amount of two different sizes of ribosomal DNA repeat units. The specificity and peculiar properties of the plant system used allowed us to assign an intrachromosomal location (short arm of the chromosomes 1B, 1R or 6B) to several ribosomal DNA repeat units that differ by the length of their nontranscribed spacer region.     

Glycerol effect on spiramycin production and valine catabolism in Streptomyces ambofaciens

Spiramycin production by Streptomyces ambofaciens in a chemically defined medium, with valine as nitrogen source, was controlled by the nature and the concentration of the carbon source. The production of this antibiotic was better in dextrins than in glycerol-containing medium. The negative effect of glycerol could be attributed in part to an excess of energy and a high specific growth rate. The intracellular ATP content, at the start of spiramycin production, was twofold higher in glycerol than in dextrin-containing medium. Increasing the initial concentrations of glycerol led to an increase in the specific growth rate and a drop in spiramycin production. Comparison between glycerol and a protein synthesis inhibitor effects and the use of resting cell systems (RCS) proved that glycerol exerted both inhibitory and repressive actions on spiramycin production independently from the growth. At the enzymatic level, glycerol interfered with valine catabolism by repressing partially valine dehydrogenase (VDH) and -ketoisoisovalerate dehydrogenase (KIVDH), generator of spiramycin aglycone precursors.     

The cytocompatibility of compound polyester-protein surfaces using an in vitro technique

Summary To avoid the need to preclot porous polyester (Dacron) vascular prostheses, we have proposed the use of a protein coating that will promote the growth and adhesion of endothelial cells. This study assessed the relative advantages of coating woven, knitted, and velour polyester fabrics with albumin, collagen, and a albumin-collagen mixture after preservation in saline or drying by a commercial dehydration process. Preclotted fabrics were used as controls. The cytocompatibility of these biopolymers was measured by an organotypic culture technique which relies on the migration of chick embryonic endothelial cells. After 7 d of culture the cytocompatibility was quantified by counting the cells in the area of migration and the morphology of the endothelial cells was observed by scanning electron microscopy. In general, the knitted and velour fabrics showed superior compatibility than the woven one. The results confirmed that collagen, either alone or combined with albumin, provides in most cases a more cytocompatible surface than albumin alone. A cell morphology most closely resembling that of natural arterial endothelial cells was observed on the albumin-collagen substrate. This study was supported by INSERM Grant C. R. L. 82 30 16, the Medical Research Council of Canada, and the Canadian Heart Foundation.     

The gene distribution in the genomes of pea, tomato and date palm

The vast majority of genes of maize, rice, barley and wheat are contained in long gene-rich regions (collectively called the 'gene space') separated by long gene-empty regions. The gene space covers a narrow, 0.8-1.6%, GC range, possibly because of the presence of abundant transposons. Here we report that the gene space is not an exclusive property of Gramineae, because it also exists in the large genome of pea (5000 Mb). Moreover, the gene space is not just dependent upon genome size, since a gene space is found in rice (415 Mb), but not in Arabidopsis (120 Mb), nor in two other plants investigated in the present work, date palm (250 Mb) and tomato (1000 Mb).     

Whole genome sequencing of marine organisms by Oxford Nanopore Technologies: Assessment and optimization of HMW‐DNA extraction protocols

Marine habitats are Earth''s largest aquatic ecosystems, yet little is known about marine organism''s genomes. Molecular studies can unravel their genetics print, thus shedding light on specie''s adaptation and speciation with precise authentication. However, extracting high molecular weight DNA from marine organisms and subsequent DNA library preparation for whole genome sequencing is challenging. The challenges can be explained by excessive metabolites secretion that co‐precipitates with DNA and barricades their sequencing. In this work, we sought to resolve this issue by describing an optimized isolation method and comparing its performance with the most commonly reported protocols or commercial kits: SDS/phenol–chloroform method, Qiagen Genomic Tips kit, Qiagen DNeasy Plant mini kit, a modified protocol of Qiagen DNeasy Plant kit, Qiagen DNeasy Blood and Tissue kit, and Qiagen Qiamp DNA Stool mini kit. Our method proved to work significantly better for different marine species regardless of their shape, consistency, and sample preservation, improving Oxford Nanopore Technologies sequencing yield by 39 folds for Spirobranchus sp. and enabling generation of almost 10 GB data per flow cell/run for Chrysaora sp. and Palaemon sp. samples.     

Genetic variation among populations of the Hessian fly Mayetiola destructor (Diptera: Cecidomyiidae) in Morocco and Syria

The RAPD-PCR technique was used to study genetic variation within and among geographical populations of the Hessian fly, Mayetiola destructor (Say), from Morocco and Syria, associated with the fly's ability to overcome resistance in three wheat cultivars containing H5, H13 and H22 resistance genes. Variation was detected both for the level of susceptibility of the cultivars and RAPD profiles of M. destructor populations. By the use of RAPD-PCR, high genetic variability was detected among individuals and populations of M. destructor within and between areas separated geographically. The DNA fingerprints of populations of M. destructor were area-specific with Nei's measures of genetic distance ranging from 0.156 (between Abda and Beni Mellal, Morocco) to 1.977 (between Marchouch, Morocco and Lattakia, Syria). Cluster analysis of the genetic distances among the populations, identified the Syrian population as an outlier. A highly significant correlation (r = 0.81) observed between the genetic and geographic distances among the populations, provided genetic support for dispersal of the fly from its presumed origin in West Asia to Morocco.