Use of the 16S-23S ribosomal genes spacer region for the molecular typing of sphingomonads

The ability of sphingomonads in drinking water to cause community- and hospital-acquired opportunistic infections has raised the need to establish reproducible identification assays. In this study, a total of 129 isolates recovered from drinking water with yellow- to orange-pigmented colonies were distributed among 10 biotypes on the basis of colony morphology. Polymorphisms, based on the amplification and restriction digestion of the intergenic transcribed spacer (ITS) region within the 10 assigned biotypes and 18 ATCC reference strains, were used to investigate the ability of this approach to differentiate closely related sphingomonads. ITS size, which ranged between 400 and 1100 bp, did not vary enough among the different genera. However, 16 distinct banding patterns within the ATCC reference strains and 9 within the 10 biotypes were obtained through ITS restriction digestion, and the majority of the tested biotypes produced patterns similar to those generated by the ATCC strains. To our knowledge, this study is not only the first comprehensive record of the size of the ITS region in sphingomonads, it is also the first study that describes the use of ITS restriction digestion to subtype those isolates

Sulfate assimilation in Rhodopseudomonas globiformis

Rhodopseudomonas globiformis is able to grow on sulfate as sole source of sulfur, but only at concentrations below 1 mM. Good growth was observed with thiosulfate, cysteine or methionine as sulfur sources. Tetrathionate supported slow growth. Sulfide and sulfite were growth inhibitory. Growth inhibition by higher sulfate concentrations was overcome by the addition of O-acetylserine, which is known as derepressor of sulfate-assimilating enzymes, and by reduced glutathione. All enzymes of the sulfate assimilation pathway. ATP-sulfurylase, adenylylphosphate-sulfotransferase, thiosulfonate reductase and O-acetylserine sulfhydrylase are present in R. globiformis. Sulfate was taken up by the cells and the sulfur incorporated into the amino acids cysteine, methionine and homocysteine. It is concluded, that the failure of R. globiformis to grow on higher concentrations of sulfate is caused by disregulation of the sulfate assimilation pathway. Some preliminary evidence for this view is given in comparing the activities of some of the involved enzymes after growth on different sulfur sources and by examining the effect of O-acetylserine on these activities

Geographical Structure of the Y-chromosomal Genetic Landscape of the Levant: A coastal-inland contrast

We have examined the male-specific phylogeography of the Levant and its surroundings by analyzing Y-chromosomal haplogroup distributions using 5874 samples (885 new) from 23 countries. The diversity within some of these haplogroups was also examined. The Levantine populations showed clustering in SNP and STR analyses when considered against a broad Middle-East and North African background. However, we also found a coastal-inland, east-west pattern of diversity and frequency distribution in several haplogroups within the small region of the Levant. Since estimates of effective population size are similar in the two regions, this strong pattern is likely to have arisen mainly from differential migrations, with different lineages introduced from the east and west

General methodology

Abdelnour, G. A., Abouchedid, K., Aguayo, M., Bakkali, M., Baroud, F., Belhani, A., ... Ykhlef, N. (2017). Introduction. In J. B. Govantes Romero, & E. Mellado Durán (Eds.), EURO-MEDITERRANEAN INTEGRATION THROUGH LIFELONG LEARNING (EU-MILL): A memory of cooperation and dialogue on Education in the Mediterranean basin (pp. 19-47). (Divulgación Científica). Universidad de Sevilla. https://doi.org/10.12795/9788447221042publishersversionpublishe