Genetic diversity and spatial structure of the Rufous‐throated Antbird (Gymnopithys rufigula), an Amazonian obligate army‐ant follower

Amazonian understory antbirds are thought to be relatively sedentary and to have limited dispersal ability; they avoid crossing forest gaps, and even narrow roads through a forest may limit their territories. However, most evidence for sedentariness in antbirds comes from field observations and plot‐based recapture of adult individuals, which do not provide evidence for lack of genetic dispersal, as this often occurs through juveniles. In this study, we used microsatellite markers and mitochondrial control‐region sequences to investigate contemporary and infer historical patterns of genetic diversity and structure of the Rufous‐throated Antbird (Gymnopithys rufigula) within and between two large reserves in central Amazonia. Analyses based on microsatellites suggested two genetically distinct populations and asymmetrical gene flow between them. Within a population, we found a lack of genetic spatial autocorrelation, suggesting that genotypes are randomly distributed and that G. rufigula may disperse longer distances than expected for antbirds. Analyses based on mitochondrial sequences did not recover two clear genetic clusters corresponding to the two reserves and indicated the whole population of the Rufous‐throated Antbird in the region has been expanding over the last 50,000 years. Historical migration rates were low and symmetrical between the two reserves, but we found evidence for a recent unilateral increase in gene flow. Recent differentiation between individuals of the two reserves and a unilateral increase in gene flow suggest that recent urban expansion and habitat loss may be driving changes and threatening populations of Rufous‐throated Antbird in central Amazonia. As ecological traits and behavioral characteristics affect patterns of gene flow, comparative studies of other species with different behavior and ecological requirements will be necessary to better understand patterns of genetic dispersal and effects of urban expansion on Amazonian understory antbirds.     

Ring test for low levels of N-(2-hydroxyethyl)valine in human hemoglobin.

Hemoglobin adducts are useful for the identification and quantification of electrophilic agents in vivo. A modified Edman degradation method has been extensively used for monitoring exposure to ethylene oxide through gas chromatographic-mass spectrometric measurements of hydroxyethyl adducts to the N-terminal valines in hemoglobin. In a ring test, four laboratories using different versions of the method analyzed eight human globin samples with low adduct levels from ethylene oxide. Measurements of the same adduct by a radioimmunoassay were also included. Strong correlation between the measurements by the different laboratories shows that the method in principle works well. However, there were some systematic quantitative differences.     

Synthesis from pullulan of spacer-arm, lipid, and ethyl glycosides of a tetrasaccharide [alpha-D-Glc-(1----6)-alpha-D-Glc-(1----4)-alpha-D-Glc-(1----4)-D-Glc] found in human urine; preparation of neoglycoproteins

Enzymic hydrolysis of pullulan, followed by acetylation and chromatography, gave acetylated alpha-D-Glcp-(1----6)-alpha-D-Glcp-(1----4)-alpha-D-Glcp-(1----4)-D-Glcp which, with 2-bromoethanol and boron trifluoride etherate in dichloromethane, gave the 2-bromoethyl glycoside. The reactions of the glycoside with methyl 3- mercaptopropionate , methyl 11- mercaptoundecanoate , and octadecanethiol are described, and also its hydrogenolysis to give an ethyl glycoside. The mercaptopropionate -derived, spacer-arm glycoside has been coupled to bovine serum albumin and keyhole limpet haemocyanin.     

Synthetic receptor analogues: preparation and calculated conformations of the 2-deoxy, 6-O-methyl, 6-deoxy, and 6-deoxy-6-fluoro derivatives of methyl 4-O-alpha-D-galactopyranosyl-beta-D-galactopyranoside (methyl beta-D-galabioside)

The 2-deoxy (7), 6-O-methyl (15), 6-deoxy (22), and 6-deoxy-6-fluoro (31) derivatives of methyl beta-D-galabioside (1) have been synthesised. Thus, 7 was prepared by xanthate reduction using tributyltin hydride, whereas 22 was obtained by catalytic hydrogenation of a 6-deoxy-6-iodogalabioside. Regioselective monofluorination of methyl 2,3-di-O-benzoyl-beta-D-galactopyranoside with Et2NSF3 and subsequent alpha-D-galactosylation provided 31. Molecular mechanics calculations yielded similar conformations for 1, 7, 15, 22, and 31 with differences in phi H and psi H of less than 5 degrees. No indications of intramolecular hydrogen bonds, as displayed by 1 in the crystal, were found for 7, 15, 22, or 31.     

High synovial expression of the inhibitory FcgammaRIIb in rheumatoid arthritis

Activating Fc gamma receptors (FcgammaRs) have been identified as having important roles in the inflammatory joint reaction in rheumatoid arthritis (RA) and murine models of arthritis. However, the role of the inhibitory FcgammaRIIb in the regulation of the synovial inflammation in RA is less known. Here we have investigated synovial tissue from RA patients using a novel monoclonal antibody (GB3) specific for the FcgammaRIIb isoform. FcgammaRIIb was abundantly expressed in synovia of RA patients, in sharp contrast to the absence or weak staining of FcgammaRIIb in synovial biopsies from healthy volunteers. In addition, the expression of FcgammaRI, FcgammaRII and FcgammaRIII was analyzed in synovia obtained from early and late stages of RA. Compared with healthy synovia, which expressed FcgammaRII, FcgammaRIII but not FcgammaRI, all activating FcgammaRs were expressed and significantly up-regulated in RA, regardless of disease duration. Macrophages were one of the major cell types in the RA synovium expressing FcgammaRIIb and the activating FcgammaRs. Anti-inflammatory treatment with glucocorticoids reduced FcgammaR expression in arthritic joints, particularly that of FcgammaRI. This study demonstrates for the first time that RA patients do not fail to up-regulate FcgammaRIIb upon synovial inflammation, but suggests that the balance between expression of the inhibitory FcgammaRIIb and activating FcgammaRs may be in favour of the latter throughout the disease course. Anti-inflammatory drugs that target activating FcgammaRs may represent valuable therapeutics in this disease.     

Lateral force transmission between human tendon fascicles.

Whether adjacent collagen fascicles transmit force in parallel is unknown. The purpose of the present study was to examine the magnitude of lateral force transmission between adjacent collagen fascicles from the human patellar and Achilles tendon. From each sample two adjacent strands of fascicles (phi 300-530 mum) enclosed in a fascicular membrane were dissected. The specimen was deformed to approximately 3% strain in three independent load-displacement cycles in a small-scale tensile testing device. Cycle 1: the fascicles and the fascicular membrane were intact. Cycle 2: one fascicle was transversally cut while the other fascicle and the fascicular membrane were kept intact. Cycle 3: both fascicles were cut in opposite ends while the fascicular membrane was left intact. A decline in peak force of 45% and 55% from cycle 1 to cycle 2, and 93% and 92% from cycle 2 to cycle 3 was observed in the patellar and Achilles tendon fascicles, respectively. A decline in stiffness of 39% and 60% from cycle 1 to cycle 2, and of 93% and 100% from cycle 2 to cycle 3 was observed in the patellar and Achilles tendon fascicles, respectively. The present data demonstrate that lateral force transmission between adjacent collagen fascicles in human tendons is small or negligible, suggesting that tendon fascicles largely act as independent structures and that force transmission principally takes place within the individual fascicles.     

Intra-articular fms-like tyrosine kinase 3 ligand expression is a driving force in induction and progression of arthritis

Background

One of the hallmarks of rheumatoid arthritis (RA) is hyperplasia and inflammation of the synovial tissue being characterized by in situ occurrence of highly differentiated leukocytes. Fms-like tyrosine kinase 3 (Flt3) has a crucial role in hematopoiesis, regulation of cell proliferation, differentiation and apoptosis. Typically, Flt3 is expressed on early myeloid and lymphoid progenitors and is activated by its soluble ligand (Flt3-L). The highly differentiated cellular pattern in the synovium of the RA patients made us hypothesize that Flt3-L, with its ability to induce proliferation and differentiation, could be of importance in induction and/or progression of arthritis.

Methodology/Principal Findings

To investigate occurrence of Flt3-L in RA we have measured its levels in matched serum and synovial fluid samples from 130 patients and 107 controls. To analyse the pro-inflammatory role of Flt3-L, we continuously overexpressed this protein locally in healthy mouse joints using homologous B-cell line transfected with Flt3-L gene. Additionally, recombinant Flt3-L was instillated intra-articularly in combination with peptidoglycans, a Toll Like Receptor 2-ligand with stong arthritogenic properties. Our results show significantly higher levels of Flt3-L in the synovial fluid as compared to serum levels in RA subjects (p = 0.0001). In addition, RA synovial fluid levels of Flt-3-L were significantly higher than these obtained from synovial fluids originating from non-inflammatory joint diseases (p = 0.022). Intra-articular administration of B-cell line transfected with Flt3-L gene resulted in highly erosive arthritis while inoculation of the same B-cell line without hyperexpression of Flt3-L did not induce erosivity and only in a minority of cases caused synovial proliferation! Flt3-ligand potentiated peptidoglycan induced arthritis as compared to mice injected with peptidoglycan alone (p<0.05).

Conclusions/Significance

Our findings indicate that Flt3-L is strongly expressed at the site of inflammation in human RA. It exerts both pro-inflammatory and tissue destructive properties once in the joint cavity. Owing to these properties, treatment attempts to neutralize this molecule should be considered in RA.