Revisiting the tangential oscillations of the tool to form the microrelief of the workpiece surface

The article is focused on the possibilities of using the tangential oscillations of the tool to form a microrelief of the workpiece surface. The diagram of the cutting tool oscillation trajectory during vibrational turning is presented. The scheme for calculation of the values of two tangential oscillation components is presented. The photos of the surfaces obtained by machining of the workpieces with the use of vibrational turning are provided. The results of the surface microgeometry modeling under the turning with tangential oscillations imposition of the tool are given. The dependence of the surface microgeometry height on the workpiece rotation speed and the tool oscillation frequency is determined. The factors which influence on the workpiece surface microgeometry formation are specified

Transcriptomic Studies in Non-Model Plants: Case of Pisum sativum L. and Medicago lupulina L.

Transcriptomics is a dynamically developing branch of biology highly important for geneticists and molecular ecologists alike. A large number of studies concerning differential gene expression, mapping of genes and quantitative trait loci (QTL), analysis of genotyping variations and so on has been conducted recently on several non‐model plants using next‐generation sequencing techniques. One example of non‐model legumes is garden pea (Pisum sativum L.), a valuable pulse crop capable of forming nitrogen‐fixing nodules and arbuscular mycorrhiza. Adaptation of standardised RNA‐seq approaches and data analysis developed for model plants to P. sativum should facilitate both studying of pea molecular genetics and breeding of new cultivars possessing agriculturally important traits. Another non‐model legume is black medick Medicago lupulina L. (a close relative of model legume plant barrel medick, Medicago truncatula Gaertn.), for which unique genetic lines almost obligatory dependent on arbuscular mycorrhiza symbiosis formation have been obtained. Such lines show promise as the perfect model for studying the genetic bases of arbuscular mycorrhiza development. In this chapter, we give a brief description of the current developments in the field of garden pea and black medick transcriptomics. Our aim is to provide a quick start guide to the non‐expert researchers for next‐generation sequencing (NGS)‐based transcriptome analysis

Concept, opportunities and challenges of urban tourism in the Arab world: Case studies of Dubai, Cairo and Amman

This paper aims to provide a better understanding of the current situation of urban tourism with referring to the experiences of the Arab World. By using bibliographic documentation and descriptive-analytic method, this paper addresses the main opportunities, impediments, and challenges of urban tourism in three Arab cities (Dubai, Cairo and Amman). This paper indicates that the three cities have many opportunities stemming from their location and their rich tourism resources. Moreover, urban tourism in these cities should confront some internal (country based) and external (global and regional) challenges such as seasonality, pollution, congestion, competition, funding and instability. Some recommendations and policy implications were suggested. The paper concludes, by arguing, that common internal and external challenges need to be addressed in a systematic manner within the broader cultural and tourism policy context in which urban tourism is now implicated. There is a lack of literature on urban tourism within the Arab countries, which is attributed to that tourism in the Arab world is heritage dominated type. Therefore, this research also attempts to bridge the gap in the existing literature about urban tourism in the Arab cities

Mapping-by-sequencing using NGS-based 3′-MACE-Seq reveals a new mutant allele of the essential nodulation gene Sym33 (IPD3) in pea (Pisum sativum L.)

Large collections of pea symbiotic mutants were accumulated in the 1990s, but the causal genes for a large portion of the mutations are still not identified due to the complexity of the task. We applied a Mapping-by-Sequencing approach including Bulk Segregant Analysis and Massive Analysis of cDNA Ends (MACE-Seq) sequencing technology for genetic mapping the Sym11 gene of pea which controls the formation of symbioses with both nodule bacteria and arbuscular-mycorrhizal fungi. For mapping we developed an F2-population from the cross between pea line N24 carrying the mutant allele of sym11 and the wild type NGB1238 (=JI0073) line. Sequencing libraries were prepared from bulks of 20 plants with mutant and 12 with wild-type phenotype. MACE-Seq differential gene expression analysis between mutant-phenotype and wild-type-phenotype bulks revealed 2,235 genes, of which 514 (23%) were up-regulated and 1,721 (77%) were down-regulated in plant roots inoculated with rhizobia as a consequence of sym11 mutation. MACE-Seq also detected single nucleotide variants between bulks in 217 pea genes. Using a novel mathematical model we calculated the recombination frequency (RF) between the Sym11 gene and these 217 polymorphic genes. Six genes with the lowest RF were converted into CAPS or dCAPS markers and genetically mapped on the complete mapping population of 108 F2-plants which confirmed their tight linkage to Sym11 and to each other. The Medicago truncatula Gaertn. (Mt) homologs of these genes are located in a distinct region of Mt chromosome 5, which corresponds to linkage group I of pea. Among 94 candidate genes from this region only one was down-regulated—the pea Sym33 homolog of the Mt IPD3 gene which is essential for nodulation. Sequencing of the Sym33 allele of the N24 (sym11) mutant revealed a single nucleotide deletion (c.C319del) in its third exon resulting in a codon shift in the open reading frame and premature translation termination. Thus, we identified a novel mutant allele sym33-4 most probably responsible for the mutant phenotype of the N24 (sym11) line, thereby demonstrating that mapping by MACE-Seq can be successfully used for genetic mapping of mutations and identification of candidate genes in pea

Defining the Rhizobium leguminosarum Species Complex

Bacteria currently included in Rhizobium leguminosarum are too diverse to be considered a single species, so we can refer to this as a species complex (the Rlc). We have found 429 publicly available genome sequences that fall within the Rlc and these show that the Rlc is a distinct entity, well separated from other species in the genus. Its sister taxon is R. anhuiense. We constructed a phylogeny based on concatenated sequences of 120 universal (core) genes, and calculated pairwise average nucleotide identity (ANI) between all genomes. From these analyses, we concluded that the Rlc includes 18 distinct genospecies, plus 7 unique strains that are not placed in these genospecies. Each genospecies is separated by a distinct gap in ANI values, usually at approximately 96% ANI, implying that it is a ‘natural’ unit. Five of the genospecies include the type strains of named species: R. laguerreae, R. sophorae, R. ruizarguesonis, “R. indicum” and R. leguminosarum itself. The 16S ribosomal RNA sequence is remarkably diverse within the Rlc, but does not distinguish the genospecies. Partial sequences of housekeeping genes, which have frequently been used to characterize isolate collections, can mostly be assigned unambiguously to a genospecies, but alleles within a genospecies do not always form a clade, so single genes are not a reliable guide to the true phylogeny of the strains. We conclude that access to a large number of genome sequences is a powerful tool for characterizing the diversity of bacteria, and that taxonomic conclusions should be based on all available genome sequences, not just those of type strains

Defining the Rhizobium leguminosarum Species Complex

Bacteria currently included in Rhizobium leguminosarum are too diverse to be considered a single species, so we can refer to this as a species complex (the Rlc). We have found 429 publicly available genome sequences that fall within the Rlc and these show that the Rlc is a distinct entity, well separated from other species in the genus. Its sister taxon is R. anhuiense. We constructed a phylogeny based on concatenated sequences of 120 universal (core) genes, and calculated pairwise average nucleotide identity (ANI) between all genomes. From these analyses, we concluded that the Rlc includes 18 distinct genospecies, plus 7 unique strains that are not placed in these genospecies. Each genospecies is separated by a distinct gap in ANI values, usually at approximately 96% ANI, implying that it is a ‘natural’ unit. Five of the genospecies include the type strains of named species: R. laguerreae, R. sophorae, R. ruizarguesonis, “R. indicum” and R. leguminosarum itself. The 16S ribosomal RNA sequence is remarkably diverse within the Rlc, but does not distinguish the genospecies. Partial sequences of housekeeping genes, which have frequently been used to characterize isolate collections, can mostly be assigned unambiguously to a genospecies, but alleles within a genospecies do not always form a clade, so single genes are not a reliable guide to the true phylogeny of the strains. We conclude that access to a large number of genome sequences is a powerful tool for characterizing the diversity of bacteria, and that taxonomic conclusions should be based on all available genome sequences, not just those of type strains

THE ANALYSIS OF THE INTRAPOPULATION VARIATION OF THE ALMOND-LEAVED AND GRAY-LEAVED WILLOWS, TO BE CONDITIONED BY THE INFLUENCE OF THE GENETICO-ECOLOGICAL FACTORS

The object of investigation: the natural populations of the almond-leaved and gray-leaved willows on the territory of the Desninsky Polesje. The purpose of the work: to establish the main laws of the intrapopulation variation of the almond-leaved and gray-leaved willows. The new type of the meiosis of the plants has been described, the high level of the aneuploidy in the populations has been established; the correlative-combination quazicontinuous character of the variation of the vegetative organs and the length of the pollen grains has been revealed. The method of revealation of the aneuploidy has been developed with the aid of the palinometric analysis; the dependence of the pollen grains dimensions on the conditions of inhabitation has been established.Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Draft genome of the strain RCAM1026 Rhizobium leguminosarum bv. viciae

Rhizobium leguminosarum bv. viciae RCAM1026 is a strain first isolated in 1964 from nodules of “Ramensky 77” cultivar of garden pea (Pisum sativum L.) now routinely used as a model strain in inoculation experiments on pea. Assembly with SPAdes yielded 133 contigs longer then 200 bp (N50 = 202,321, GC% = 60.84). Resulting annotated genome is 7,248,686 bp encoding 6792 genes