A chromosomal genetic map of Rhizobium sp. NGR234 generated with Tn5-Mob

Summary Rhizobium sp. NGR234 in a fast-growing Rhizobium strain with a broad host range. The location and role of chromosomal genes involved in cellular metabolism or in the legume symbioses is unknown. We isolated a series of auxotrophic and antibiotic resistant mutants of NGR234 and utilized a chromosome mobilization system based on Tn5-Mob and pJB3JI; Tn5-Mob donor strains behaved like Hfr strains, transferring the chromosome polarly at high frequency from a fixed point of insertion. The use of four different strains with Tn5-Mob located at different nutritional loci in crosses with double auxotrophic recipients, allowed us to build up a circular linkage map of NGR234 based on relative recombination frequencies. Also, symbiotically important genes identified by site-directed mutagenesis, such as hemA and ntrA, could be located and mapped on the chromosome.Abbreviations Tc tetracycline - Sp spectinomycin - Rif rifampicin - Km kanamycin     

Torres Strait Islanders Stories from an Exhibition

Preparations for a centenary exhibition to mark the 1898 Cambridge Anthropological Expedition to the Torres Strait incorporated cross-cultural collaborative work, reflecting the changing roles of museums as sites for contact and research combining curatorial expertise and indigenous knowledge. Specific objects in the collections of the University of Cambridge Museum of Archaeology and Anthropology continue to be active intermediaries in the relationship between museum staff and Torres Strait Islanders and the museum itself has become an important field site. This paper provides an ethnography of the process of creating the exhibition and explores different ways that many of the objects displayed have resonance for Islanders today.     

Alta prevalencia de obesidad en una población laboral en España

Background and objectivesTo report the prevalence of obesity in a Spanish working population and its changes in recent years.Material and methodsData were collected from routine medical examinations performed on workers by a national mutual insurance society for occupational accidents and diseases (Ibermutuamur). A structured questionnaire was completed and physical examinations were performed. Overweight was defined as BMI ranging from 25 and 29.9, obesity as BMI of 30-39.9, and morbid obesity as BMI ≥ 40 kg/m².ResultsData from 1,336,055 medical examinations performed from May 2004 to November 2007 were collected. Prevalence rates in the population examined in 2004 (n = 230,684; 73% males; average age, 36.4 years) were: morbid obesity, 0.5% (0.6% males, 0.5% females); obesity, 14.5% (17.0% males, 7.7% females); overweight, 38.4% (44.8% males, 21.3% females). Prevalence rates of obesity and overweight were higher in blue-collar workers (16.4% and 40.5% respectively) as compared to white-collar workers (10.9% and 34.4% respectively). There was a progressive increase in prevalence of obesity during the 4-year study (2004-2007) in both males (17.0%, 17.6%, 17.9%, 18.2%) and females (7.6%, 8.0%, 8.4%, 8.7%).ConclusionsPrevalence of obesity and overweight in the Spanish working population is high, especially in male blue-collar workers, and is increasing. There is a need to promote early prevention programs and specific treatments for obesity.     

The peptide repertoires of HLA-B27 subtypes differentially associated to spondyloarthropathy (B*2704 and B*2706) differ by specific changes at three anchor positions

HLA-B*2704 is strongly associated with ankylosing spondylitis. B*2706, which differs from B*2704 by two amino acid changes, is not associated with this disease. A systematic comparison of the B*2704- and B*2706-bound peptide repertoires was carried out to elucidate their overlap and differential features and to correlate them with disease susceptibility. Both subtypes shared about 90% of their peptide repertoires, consisting of peptides with Arg(2) and C-terminal aliphatic or Phe residues. B*2706 polymorphism influenced specificity at three anchor positions: it favored basic residues at P3 and POmega-2 and impaired binding of Tyr and Arg at POmega. Thus, the main structural feature of peptides differentially bound to B*2704 was the presence of C-terminal Tyr or Arg, together with a strong preference for aliphatic/aromatic P3 residues. This is the only known feature of B*2704 and B*2706 that correlates to their differential association with spondyloarthropathy. The concomitant presence of basic P3 and POmega-2 residues was observed only among peptides differentially bound to B*2706, suggesting that it impairs binding to B*2704. Similarity between peptide overlap and the degree of cross-reaction with alloreactive T lymphocytes suggested that the majority of shared ligands maintain unaltered antigenic features in the context of both subtypes.     

Differential sensitivity to detergents of actin cytoskeleton from nerve endings

Detergent-resistant membranes (DRM), an experimental model used to study lipid rafts, are typically extracted from cells by means of detergent treatment and subsequent ultracentrifugation in density gradients, Triton X-100 being the detergent of choice in most of the works. Since lipid rafts are membrane microdomains rich in cholesterol, depletion of this component causes solubilization of DRM with detergent. In previous works from our group, the lack of effect of cholesterol depletion on DRM solubilization with Triton X-100 was detected in isolated rat brain synaptosomes. In consequence, the aim of the present work is to explore reasons for this observation, analyzing the possible role of the actin cytoskeleton, as well as the use of an alternative detergent, Brij 98, to overcome the insensitivity to Triton X-100 of cholesterol-depleted DRM. Brij 98 yields Brij-DRM that are highly dependent on cholesterol, since marker proteins (Flotillin-1 and Thy-1), as well as actin, appear solubilized after MCD treatment. Pretreatment with Latrunculin A results in a significant increase in Flotillin-1, Thy-1 and actin solubilization by Triton X-100 after cholesterol depletion. Studies with transmission electron microscopy show that combined treatment with MCD and Latrunculin A leads to a significant increase in solubilization of DRM with Triton X-100. Thus, Triton-DRM resistance to cholesterol depletion can be explained, at least partially, thanks to the scaffolding action of the actin cytoskeleton, without discarding differential effects of Brij 98 and Triton X-100 on specific membrane components. In conclusion, the detergent of choice is important when events that depend on the actin cytoskeleton are going to be studied.     

Dynamic modulation of FGFR1–5-HT1A heteroreceptor complexes. Agonist treatment enhances participation of FGFR1 and 5-HT1A homodimers and recruitment of β-arrestin2

New findings show that neurotrophic and antidepressant effects of 5-HT in brain can, in part, be mediated by activation of the 5-HT1A receptor protomer in the hippocampal and raphe FGFR1–5-HT1A heteroreceptor complexes enhancing the FGFR1 signaling. The dynamic agonist modulation of the FGFR1–5-HT1A heteroreceptor complexes and their recruitment of β-arrestin is now determined in cellular models with focus on its impact on 5-HT1AR and FGFR1 homodimerization in the heteroreceptor complexes based on BRET² assays. The findings show that coagonist treatment with 8-OH-DPAT and FGF2 but not treatment with the 5-HT1A agonist alone markedly increases the BRETmax values and significantly reduces the BRET50 values of 5HT1A homodimerization. The effects of FGF2 or FGF20 with or without the 5-HT1A agonist were also studied on the FGFR1 homodimerization of the heteroreceptor complexes. FGF2 produced a marked and rapid increase in FGFR1 homodimerization which partially declined over a 10 min period. Cotreatment with FGF2 and 5-HT1A agonist blocked this decline in FGFR1 homodimerization. Furthermore, FGF2 alone produced a small increase in the BRET² signal from the 5-HT1A-β-arrestin2 receptor–protein complex which was additive to the marked effect of 8-OH-DPAT alone. Taken together, the participation of 5-HT1A and FGFR1 homodimers and recruitment of β-arrestin2 was demonstrated in the FGFR1–5-HT1A heteroreceptor complexes upon agonist treatments.     

Disturbances, elevation, topography and spatial proximity drive vegetation patterns along an altitudinal gradient of a top biodiversity hotspot

The correlation between vegetation patterns (species distribution and richness) and altitudinal variation has been widely reported for tropical forests, thereby providing theoretical basis for biodiversity conservation. However, this relationship may have been oversimplified, as many other factors may influence vegetation patterns, such as disturbances, topography and geographic distance. Considering these other factors, our primary question was: is there a vegetation pattern associated with substantial altitudinal variation (10–1,093 m a.s.l.) in the Atlantic Rainforest—a top hotspot for biodiversity conservation—and, if so, what are the main factors driving this pattern? We addressed this question by sampling 11 1-ha plots, applying multivariate methods, correlations and variance partitioning. The Restinga (forest on sandbanks along the coastal plains of Brazil) and a lowland area that was selectively logged 40 years ago were floristically isolated from the other plots. The maximum species richness (>200 spp. per hectare) occurred at approximately 350 m a.s.l. (submontane forest). Gaps, multiple stemmed trees, average elevation and the standard deviation of the slope significantly affected the vegetation pattern. Spatial proximity also influenced the vegetation pattern as a structuring environmental variable or via dispersal constraints. Our results clarify, for the first time, the key variables that drive species distribution and richness across a large altitudinal range within the Atlantic Rainforest.     

The VIRCA Project: virus resistant cassava for Africa

The VIRCA (Virus Resistant Cassava for Africa) project is a collaborative program between the Donald Danforth Plant Science Center, USA the National Crops Resources Research Institute, Uganda and the Kenya Agricultural Research Institute, Kenya. VIRCA is structured to include all aspects of the intellectual property, technology, regulatory, biosafety, quality control, communication and distribution components required for a GM crop development and delivery process. VIRCA's goal is to improve cassava for resistance to the viral diseases cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) using pathogen-derived RNAi technology, and to field test, obtain regulatory approval for and deliver these products to small landholder farmers. During Phase I of the project, proof of concept was achieved by production and testing of virus resistant plants under greenhouse and confined field trials in East Africa. In VIRCA Phase II, two farmer-preferred varieties will be modified for resistance to CBSD and CMD, and lead events identified after molecular and field screening. In addition to delivery of royalty-free improved planting materials for farmers, VIRCA capacity building activities are enhancing indigenous capability for crop biotechnology in East Africa.     

The gut anaerobe Faecalibacterium prausnitzii uses an extracellular electron shuttle to grow at oxic–anoxic interphases

Faecalibacterium prausnitzii is one of the most abundant bacteria in the human gut ecosystem and it is an important supplier of butyrate to the colonic epithelium. Low numbers of faecalibacteria have been associated with inflammatory bowel disease. Despite being extremely oxygen sensitive, F. prausnitzii is found adherent to the gut mucosa where oxygen diffuses from epithelial cells. This paradox is now explained on the basis of gas tube experiments, flavin-dependent reduction of 5,5′-dithiobis-2-nitrobenzoate and microbial fuel cell experiments. The results show that F. prausnitzii employs an extracellular electron shuttle of flavins and thiols to transfer electrons to oxygen. Both compounds are present in the healthy human gut. Our observations may have important implications for the treatment of patients with Crohn''s disease, for example, with flavin- or antioxidant rich diets, and they provide a novel key insight in host–microbe interactions at the gut barrier.