Base-compositional biases and the bat problem. III. The questions of microchiropteran monophyly.

Using single-copy DNA hybridization, we carried out a whole genome study of 16 bats (from ten families) and five outgroups (two primates and one each dermopteran, scandentian, and marsupial). Three of the bat species represented as many families of Rhinolophoidea, and these always associated with the two representatives of Pteropodidae. All other microchiropterans, however, formed a monophyletic unit displaying interrelationships largely in accord with current opinion. Thus noctilionoids comprised one clade, while vespertilionids, emballonurids, and molossids comprised three others, successively more closely related in that sequence. The unexpected position of rhinolophoids may be due either to the high AT bias they share with pteropodids, or it may be phylogenetically authentic. Reanalysis of the data with varying combinations of the five outgroups does not indicate a rooting problem, and the inclusion of many bat lineages divided at varying levels similarly discounts long branch attraction as an explanation for the pteropodid-rhinolophoid association. If rhinolophoids are indeed specially related to pteropodids, many synapomorphies of Microchiroptera are called into question, not least the unitary evolution of echolocation (although this feature may simply have been lost in pteropodids). Further, a rhinolophoid-pteropodid relationship--if true--has serious implications for the classification of bats. Finally, among the outgroups, an apparent sister-group relation of Dermoptera and Primates suggests that flying lemurs do not represent the ancestors of some or all bats; yet, insofar as gliding of the type implemented in dermopterans is an appropriate model for the evolution of powered mammalian flying, the position of Cynocephalus in our tree indirectly strengthens the argument that true flight could have evolved more than once among bats.     

Synovial explant inflammatory mediator production corresponds to rheumatoid arthritis imaging hallmarks: a cross-sectional study

Introduction

Despite the widespread use of magnetic resonance imaging (MRI) and Doppler ultrasound for the detection of rheumatoid arthritis (RA) disease activity, little is known regarding the association of imaging-detected activity and synovial pathology. The purpose of this study was to compare site-specific release of inflammatory mediators and evaluate the corresponding anatomical sites by examining colour Doppler ultrasound (CDUS) and MRI scans.

Methods

RA patients were evaluated on the basis of CDUS and 3-T MRI scans and subsequently underwent synovectomy using a needle arthroscopic procedure of the hand joints. The synovial tissue specimens were incubated for 72 hours, and spontaneous release of monocyte chemoattractant protein 1 (MCP-1), interleukin 6 (IL-6), macrophage inflammatory protein 1β (MIP-1β) and IL-8 was measured by performing multiplex immunoassays. Bone marrow oedema (BME), synovitis and erosion scores were estimated on the basis of the rheumatoid arthritis magnetic resonance imaging score (RAMRIS). Mixed models were used for the statistical analyses. Parsimony was achieved by omitting covariates with P > 0.1 from the statistical model.

Results

Tissue samples from 58 synovial sites were obtained from 25 patients. MCP-1 was associated with CDUS activity (P = 0.009, approximate Spearman’s ρ = 0.41), RAMRIS BME score (P = 0.01, approximate Spearman’s ρ = 0.42) and RAMRIS erosion score (P = 0.03, approximate Spearman’s ρ = 0.31). IL-6 was associated with RAMRIS synovitis score (P = 0.04, approximate Spearman’s ρ = 0.50), BME score (P = 0.04, approximate Spearman’s ρ = 0.31) and RAMRIS erosion score (P = 0.03, approximate Spearman’s ρ = 0.35). MIP-1β was associated with CDUS activity (P = 0.02, approximate Spearman’s ρ = 0.38) and RAMRIS synovitis scores (P = 0.02, approximate Spearman’s ρ = 0.63). IL-8 associations with imaging outcome measures did not reach statistical significance.

Conclusions

The association between imaging activity and synovial inflammatory mediators underscores the high sensitivity of CDUS and MRI in the evaluation of RA disease activity. The associations found in our present study have different implications for synovial mediator releases and corresponding imaging signs. For example, MCP-1 and IL-6 were associated with both general inflammation and bone destruction, in contrast to MIP-1β, which was involved solely in general synovitis. The lack of association of IL-8 with synovitis was likely underestimated because of a large proportion of samples above assay detection limits among the patients with the highest synovitis scores.     

Isolation and identification of mucinolytic actinomycetes

Biochemical and physiological tests, and 16S rRNA gene sequences, were used to classify nine Actinomycete strains isolated from soil and sand samples in Thailand. These strains were isolated based on their ability to readily degrade mucin glycoproteins. A turbidometric based mucinolytic assay was developed to confirm this. In addition all strains showed significant production of proteases. Phylogenetic analysis of the strains revealed that from the nine isolated Actinomycete strains eight were closely related to Streptomyces species and one was identified as belonging to the genus Kitasatospora. The biochemical and physiological tests performed identified two strain pairs that were similar (with only 3.9% difference observed) and this was in accordance with the phylogenetic results obtained. The remaining strains were distinct from each other, with the soil-isolated strains forming a separate clade to the sand-isolated strains in the inferred phylogenetic trees. The isolated mucinolytic Actinomycete strains will be the subject of further investigations into their proteolytic and glycosidic activity. Mucin degrading enzymes such as these are studied for their potential to be used for the development of a drug delivery system.     

Yeast iso-1-cytochrome c. A 2.8 A resolution three-dimensional structure determination

A molecular replacement approach, augmented with the results of predictive modeling procedures, solvent accessibility studies, packing analyses and translational coefficient searches, has been used to elucidate the 2.8 A (1 A = 0.1 nm) resolution structure of yeast iso-1-cytochrome c. An examination of the polypeptide chain folding of this protein shows it to have unique conformations in three regions, upon comparison with the structures of other eukaryotic cytochromes c. These include: residues -5 to +1 at the N-terminal end of the polypeptide chain, which are in an extended conformation and project in large part off the surface of the protein; residues 19 to 26, which form a surface beta-loop on the His18 ligand side of the central heme group; and, the C-terminal end of the helical segment composed of residues 49 to 56, which serves to form a part of the heme pocket. Structural studies also show that the highly reactive sulfhydryl group of Cys102 is buried within a hydrophobic region in the monomer form of yeast iso-1-cytochrome c. Dimerization of yeast iso-1-cytochrome c through disulfide bond formation between two such residues would require a substantial conformational change in the C-terminal helix of this protein. Another unique structural feature, the trimethylated side-chain of Lys72, is located on the surface of yeast iso-1-cytochrome c near the solvent-exposed edge of the bound heme prosthetic group. On the basis of the results of these and other structural studies, an analysis of the spatial conservation of structural features in the heme pocket of eukaryotic cytochromes c has been conducted. It was found that the residues involved could be divided into three general classes. The current structural analyses and additional modeling studies have also been used to explain the altered functional properties observed for mutant yeast iso-1-cytochrome c proteins.     

Does evaluation of the ligamentous compartment enhance diagnostic utility of sacroiliac joint MRI in axial spondyloarthritis?

IntroductionInflammation of the sacroiliac joints (SIJ) is a fundamental clinical feature of axial spondyloarthritis (SpA). The anatomy of the irregularly shaped SIJ is complex with an antero-inferior cartilaginous compartment containing central hyaline and peripheral fibrocartilage, and a dorso-superior ligamentous compartment. Several scoring modules to systematically assess SIJ magnetic resonance imaging (MRI) in SpA have been developed. Nearly all of them are based on the cartilaginous joint compartment alone. However, there are only limited data about the frequency of inflammatory lesions in the ligamentous compartment and their potential diagnostic utility in axial SpA. We therefore aimed to evaluate the ligamentous compartment on sacroiliac joint MRI for lesion distribution and potential incremental value towards diagnosis of SpA over and above the traditional assessment of the cartilaginous compartment alone.MethodsTwo independent cohorts of 69 and 88 consecutive back pain patients ≤50 years were referred for suspected SpA (cohort A) or acute anterior uveitis plus back pain (cohort B). Patients were classified according to rheumatologist expert opinion based on clinical, radiographic and laboratory examination as having nonradiographic axial SpA (nr-axSpA; n = 51), ankylosing spondylitis (n = 34), or nonspecific back pain (NSBP; n = 72). Five blinded readers assessed SIJ MRI globally for presence/absence of SpA. Bone marrow edema (BME) and fat metaplasia were recorded in the cartilaginous and ligamentous compartment. The incremental value of evaluating the ligamentous additionally to the cartilaginous compartment alone for diagnosis of SpA was graded qualitatively. We determined the lesion distribution between the two compartments, and the impact of the ligamentous compartment evaluation on diagnostic utility.ResultsMRI bone marrow lesions solely in the ligamentous compartment in the absence of lesions in the cartilaginous compartment were reported in just 0–2.0/0–4.0 % (BME/fat metaplasia) of all subjects. Additional assessment of the ligamentous compartment was regarded as essential for diagnosis in 0 and 0.6 %, and as contributory in 28.0 and 7.7 % of nr-axSpA patients in cohorts A and B, respectively. Concomitant BME in both compartments was evident in 11.6–42.0 % of nr-axSpA and 2.1–2.4 % of NSBP patients.ConclusionAssessing the ligamentous compartment on SIJ MRI provided no incremental value for diagnosis of axial SpA. However, concomitant BME in both compartments may help discriminate nr-axSpA from NSBP.     

Studies on bacteria-like particles sampled from the stratosphere

Bacteria-like particles recovered from the stratosphere and deposited on cellulose acetate membranes have been analysed to confirm their bacterial nature. One particle appeared to be attached to an inorganic particle apparently by mucoid material typically produced by bacteria. A filamentous structure, morphologically similar to a fungal hypha, was also observed. EDS analysis showed that the particles were all non-mineral and therefore could be biological in nature. However, the composition of several clumps of nanobacteria-sized particles were found, by SIMS analysis, to be inconsistent with that of bacteria. The results show that it is dangerous to assume that bacteria-like particles seen under scanning electron microscopy are necessarily bacteria.     

Polyploid genome of <Emphasis Type="Italic">Camelina sativa</Emphasis>revealed by isolation of fatty acid synthesis genes

Background  

Camelina sativa, an oilseed crop in the Brassicaceae family, has inspired renewed interest due to its potential for biofuels applications. Little is understood of the nature of the C. sativa genome, however. A study was undertaken to characterize two genes in the fatty acid biosynthesis pathway, fatty acid desaturase (FAD) 2 and fatty acid elongase (FAE) 1, which revealed unexpected complexity in the C. sativa genome.