Diversité des rhizobia associés au genre Hippocrepis en Algérie

La présente étude porte sur la nature des rhizobia associés aux légumineuses du genre Hippocrepis L. qui compte une dizaine d’espèces en Algérie et pour laquelle très peu de travaux ont été jusqu’ici consacrés. Les résultats de nos investigations qui ont portés sur 26 plants représentant 8 espèces de ce genre et provenant de 17 localités du nord et du sud du pays révèlent que tous les plants étaient nodulés et fixateurs d’azote, ce qui indique que les 8 espèces identifiées sont capables d’établir une symbiose efficiente avec les rhizobia présents dans les sols qui les supportent. Le séquençage du gène de l’ARN 16S des 26 souches de rhizobia isolées et authentifiées par des tests de nodulation au laboratoire, permet de les assigner à 16 espèces de rhizobia réparties sur 5 genres : Ensifer, Mesorhizobium, Bradyrhizobium, Rhizobium et Neorhizobium avec une prédominance des représentants des genres Ensifer et Mesorhizobium. Les résultats de cette étude qui est la première dédiée spécifiquement au genre Hippocrepis indiquent que la symbiose à rhizobia et la capacité d’utiliser, par ce biais, l’azote atmosphérique sont communes chez les représentants de ce genre en Algérie, ils révèlent aussi la grande diversité des rhizobia qui sont associés à ce genre. Abstract: The present study focuses on the nature of the rhizobia associated with legumes of the genus Hippocrepis L. which counts about ten species in Algeria and for which very little work has been performed so far. The results of our investigations, which focused on 26 plants representing 8 species of this genus and coming from 17 localities in the north and south of the country, show that all plants were nodulated and nitrogen-fixing, which indicates that the species identified are capable of establishing an efficient symbiosis with the rhizobia present in the soils that support them. The sequencing of the 16S RNA gene of the 26 strains of rhizobia isolated and authenticated by nodulation tests in the laboratory, allows their assignation to16 species of rhizobia spread over 5 genera: Ensifer, Mesorhizobium, Bradyrhizobium, Rhizobium and Neorhizobium with a predominance of representatives of the genera Ensifer and Mesorhizobium. The results of this study, which is the first dedicated to the genus Hippocrepis, show that the rhizobial symbiosis and its ability to use atmospheric nitrogen are common among representatives of the genus Hippocrepis in Algeria and reveal a great diversity of associated rhizobia

Occurrence of Anaplasma phagocytophilum in goats and sheep in Hebei Province, China

Anaplasma phagocytophilum is an emerging pathogen known to cause human granulocytic anaplasmosis (HGA). Here we determined the prevalence and genetic characterization of A. phagocytophilum in Hebei Province, China. A total of 253 samples were taken from goats and sheep in Hebei Province, and 52 (20.6%) were positive for A. phagocytophilum. There was a higher positive rate in sheep (23.8%, 20/84) than in goats (18.9%, 32/169). Analysis of the partial 16S RNA gene sequences of A. phagocytophilum revealed that the isolates in this study were members of the same clade and were 100% homologous with each other. This study provides information on the epidemiologic features of A. phagocytophilum.

Ultraviolet Irradiation of Skin Alters the Faecal Microbiome Independently of Vitamin D in Mice

Reduced sunlight exposure has been associated with an increased incidence of Crohn’s disease and ulcerative colitis. The effect of ultraviolet radiation (UVR) on the faecal microbiome and susceptibility to colitis has not been explored. C57Bl/6 female mice were fed three different vitamin D-containing diets for 24 days before half of the mice in each group were UV-irradiated (1 kJ/m2) for each of four days, followed by twice-weekly irradiation of shaved dorsal skin for 35 days. Faecal DNA was extracted and high-throughput sequencing of the 16S RNA gene performed. UV irradiation of skin was associated with a significant change in the beta-diversity of faeces compared to nonirradiated mice, independently of vitamin D. Specifically, members of phylum Firmicutes, including Coprococcus, were enriched, whereas members of phylum Bacteroidetes, such as Bacteroidales, were depleted. Expression of colonic CYP27B1 increased by four-fold and IL1β decreased by five-fold, suggesting a UVR-induced anti-inflammatory effect. UV-irradiated mice, however, were not protected against colitis induced by dextran sodium sulfate (DSS), although distinct faecal microbiome differences were documented post-DSS between UV-irradiated and nonirradiated mice. Thus, skin exposure to UVR alters the faecal microbiome, and further investigations to explore the implications of this in health and disease are warranted.