The symbiosis between oriental goat’s rue and the root nodule bacteria <Emphasis Type="Italic">Rhizobium galegae</Emphasis>: Specificity and competitiveness

Competitiveness and genetic variation of the Rhizobium galegae strains from the collection of the All-Russia Institute of Agricultural Microbiology, Russian Academy of Agricultural Sciences, causing nodulation of oriental goat’s rue under conditions of Bashkortostan soils (lacking this rhizobial species) were studied. It was demonstrated that of all the tested strains, the strains CIAM 0702 and CIAM 0704, each carrying two megaplasmids of 1500 and 2000 MDa, were the most competitive. RAPD (random amplified polymorphic DNA) analysis showed that R. galegae strains were able to intensively exchange the genetic material in the host plant rhizosphere. We did not succeed in detecting the local root nodule bacteria that were either initially able to infect oriental goat’s rue or had adapted to infecting this species due to various genetic rearrangements.     

Range-wide phylogeography and gene zones in Pinus pinaster Ait. revealed by chloroplast microsatellite markers

Some 1339 trees from 48 Pinus pinaster stands were characterized by five chloroplast microsatellites, detecting a total of 103 distinct haplotypes. Frequencies for the 16 most abundant haplotypes (p(k) > 0.01) were spatially interpolated over a lattice made by 430 grid points. Fitting of spatially interpolated values on raw haplotype frequencies at the same geographical location was tested by regression analysis. A range-wide 'diversity map' based on interpolated haplotype frequencies allowed the identification of one 'hotspot' of diversity in central and southeastern Spain, and two areas of low haplotypic diversity located in the western Iberian peninsula and Morocco. Principal component analysis (PCA) carried out on haplotypes frequency surfaces allowed the construction of a colour-based 'synthetic' map of the first three PC components, enabling the detection of the main range-scale genetic trends and the identification of three main 'gene pools' for the species: (i) a 'southeastern' gene pool, including southeastern France, Italy, Corsica, Sardinia, Pantelleria and northern Africa; (ii) an 'Atlantic' gene pool, including all the western areas of the Iberian peninsula; and (iii) a 'central' gene pool, located in southeastern Spain. Multivariate and AMOVA analyses carried out on interpolated grid point frequency values revealed the existence of eight major clusters ('gene zones'), whose genetic relationships were related with the history of the species. In addition, demographic models showed more ancient expansions in the eastern and southern ranges of maritime pine probably associated to early postglacial recolonization. The delineation of the gene zones provides a baseline for designing conservation areas in this key Mediterranean pine.     

Fluorescence in situ hybridization analysis of hindgut bacteria associated with the development of equine laminitis

Carbohydrate-induced laminitis in horses is characterized by marked changes in the composition of the hindgut microbiota, from a predominantly Gram-negative population to one dominated by Gram-positive bacteria. The objective of this study was to monitor changes in the relative abundance of selected hindgut bacteria that have previously been implicated in the pathophysiology of equine laminitis using fluorescence in situ hybridization (FISH). Caecal cannulae were surgically implanted in five Standardbred horses and laminitis induced by oral administration of a bolus dose of oligofructose. Caecal fluid and faecal specimens were collected over a 48 h period at 2 to 4 h intervals post-oligofructose administration and subjected to FISH using probes specific for nine bacterial groups to determine changes in their relative abundance compared with total bacteria hybridizing to the generic EUBMIX probe. Additionally, hoof biopsies were taken over the course of the experiment at 6 h intervals and evaluated for histopathological changes consistent with laminitis, allowing changes in hindgut microbiota to be correlated with the onset of lesions in the foot. Of the microorganisms specifically targeted, streptococci of the Streptococcus bovis/equinus complex were the only bacteria that consistently proliferated in both caecal fluid and faeces immediately before the onset of histological signs of laminitis. Furthermore, lactobacilli, Enterobacteriaceae, Allisonella histaminiformans, enterococci, Bacteroides fragilis, Mitsuokella jalaludinii and Clostridium difficile did not establish significant populations in the hindgut before the onset of equine laminitis.     

Impacts of climate change on stream benthic diatoms—a nation-wide perspective of reference conditions

Hydrobiologia - Consequences of anthropogenic climate change directly affect freshwater ecosystems and their aquatic biological communities. Diatoms are amongst the most sensitive organisms to...     

Glutamate Decarboxylase-Dependent Acid Resistance in Brucella spp.: Distribution and Contribution to Fitness under Extremely Acidic Conditions

Brucella is an expanding genus of major zoonotic pathogens, including at least 10 genetically very close species occupying a wide range of niches from soil to wildlife, livestock, and humans. Recently, we have shown that in the new species Brucella microti, the glutamate decarboxylase (Gad)-dependent system (GAD system) contributes to survival at a pH of 2.5 and also to infection in mice by the oral route. In order to study the functionality of the GAD system in the genus Brucella, 47 isolates, representative of all known species and strains of this genus, and 16 strains of the closest neighbor genus, Ochrobactrum, were studied using microbiological, biochemical, and genetic approaches. In agreement with the genome sequences, the GAD system of classical species was not functional, unlike that of most strains of Brucella ceti, Brucella pinnipedialis, and newly described species (B. microti, Brucella inopinata BO1, B. inopinata-like BO2, and Brucella sp. isolated from bullfrogs). In the presence of glutamate, these species were more acid resistant in vitro than classical terrestrial brucellae. Expression in trans of the gad locus from representative Brucella species in the Escherichia coli MG1655 mutant strain lacking the GAD system restored the acid-resistant phenotype. The highly conserved GAD system of the newly described or atypical Brucella species may play an important role in their adaptation to acidic external and host environments. Furthermore, the GAD phenotype was shown to be a useful diagnostic tool to distinguish these latter Brucella strains from Ochrobactrum and from classical terrestrial pathogenic Brucella species, which are GAD negative.     

Heterologous expression and characterization of a novel halotolerant,thermostable, and alkali-stable GH6 endoglucanase from <Emphasis Type="Italic">Thermobifida halotolerans</Emphasis>

A novel endoglucanase gene was cloned from Thermobifida halotolerans YIM 90462^T, designated as thcel6A for being a member of glycoside hydrolase family 6. The gene was 1332 bp long and encoded a 443-amino-acid protein with a molecular mass of 45.9 kDa. The purified recombinant endoglucanase had optimal activity at 55 °C and pH 8.5. Thcel6A showed high hydrolytic activities at 25–55 °C and retained 58 % of initial activity after incubation at 90 °C for 1 h. It retained more than 80 % of activity after incubation for 12 h at pH values from 4 to 12. Thcel6A displayed higher hydrolytic activities in 5–15 % NaCl (w/v) than at 0 % NaCl. Activity increased 2.5-fold after incubation with 20 % (w/v) NaCl at 37 °C for 10 min. These properties suggest that this novel endoglucanase has potential for specific industrial application.