Biodiversity of pig breeds from China and Europe estimated from pooled DNA samples: differences in microsatellite variation between two areas of domestication

Microsatellite diversity in European and Chinese pigs was assessed using a pooled sampling method on 52 European and 46 Chinese pig populations. A Neighbor Joining analysis on genetic distances revealed that European breeds were grouped together and showed little evidence for geographic structure, although a southern European and English group could tentatively be assigned. Populations from international breeds formed breed specific clusters. The Chinese breeds formed a second major group, with the Sino-European synthetic Tia Meslan in-between the two large clusters. Within Chinese breeds, in contrast to the European pigs, a large degree of geographic structure was noted, in line with previous classification schemes for Chinese pigs that were based on morphology and geography. The Northern Chinese breeds were most similar to the European breeds. Although some overlap exists, Chinese breeds showed a higher average degree of heterozygosity and genetic distance compared to European ones. Between breed diversity was even more pronounced and was the highest in the Central Chinese pigs, reflecting the geographically central position in China. Comparing correlations between genetic distance and heterozygosity revealed that China and Europe represent different domestication or breed formation processes. A likely cause is a more diverse wild boar population in Asia, but various other possible contributing factors are discussed.     

Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals

Background  

Vertebrate alpha (α)- and beta (β)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the α- and β-globin clusters expanded, and then were separated onto different chromosomes. The previous finding of a fossil β-globin gene (ω) in the marsupial α-cluster, however, suggested that duplication of the α-β cluster onto two chromosomes, followed by lineage-specific gene loss and duplication, produced paralogous α- and β-globin clusters in birds and mammals. Here we analyse genomic data from an egg-laying monotreme mammal, the platypus (Ornithorhynchus anatinus), to explore haemoglobin evolution at the stem of the mammalian radiation.     

Differences in specificity and compensatory functions among three major starch synthases determine the structure of amylopectin in rice endosperm

Key message

This work adds a new player, HER2, downstream of the perception of E-2-hexenal, a green leaf volatile, and shows that E-2-hexenal specifically changes the redox status of the mitochondria.

Abstract

It is widely accepted that plants produce and respond to green leaf volatiles (GLVs), but the molecular components involved in transducing their perception are largely unknown. The GLV E-2-hexenal inhibits root elongation in seedlings and, using this phenotype, we isolated E-2-hexenal response (her) Arabidopsis thaliana mutants. Using map-based cloning we positioned the her2 mutation to the At5g63620 locus, resulting in a phenylalanine instead of serine on position 223. Knockdown and overexpression lines of HER2 confirmed the role of HER2, which encodes an oxidoreductase, in the responsiveness to E-2-hexenal. Since E-2-hexenal is a reactive electrophile species, which are known to influence the redox status of cells, we utilized redox sensitive GFP2 (roGFP2) to determine the redox status of E-2-hexenal-treated root cells. Since the signal peptide of HER2 directed mCherry to the mitochondria, we targeted the expression of roGFP2 to this organelle besides the cytosol. E-2-hexenal specifically induced a change in the redox status in the mitochondria. We did not see a difference in the redox status in her2 compared to wild-type Arabidopsis. Still, the mitochondrial redox status did not change with Z-3-hexenol, another abundant GLV. These results indicate that HER2 is involved in transducing the perception of E-2-hexenal, which changes the redox status of the mitochondria.

     

The interaction of the Rieske iron-sulfur protein with occupants of the Qo-site of the bc1 complex, probed by electron spin echo envelope modulation.

The bifurcated reaction at the Q(o)-site of the bc(1) complex provides the mechanistic basis of the proton pumping activity through which the complex conserves redox energy in the proton gradient. Structural information about the binding of quinone at the site is lacking, because the site is vacant in crystals of the native complexes. We now report the first structural characterization of the interaction of the native quinone occupant with the Rieske iron-sulfur protein in the bc(1) complex of Rhodobacter sphaeroides, using high resolution EPR. We have compared the binding configuration in the presence of quinone with the known structures for the complex with stigmatellin and myxothiazol. We have shown by using EPR and orientation-selective electron spin echo envelope modulation (ESEEM) measurements of the iron-sulfur protein that when quinone is present in the site, the isotropic hyperfine constant of one of the N(delta) atoms of a liganding histidine of the [2Fe-2S] cluster is similar to that observed when stigmatellin is present and different from the configuration in the presence of myxothiazol. The spectra also show complementary differences in nitrogen quadrupole splittings in some orientations. We suggest that the EPR characteristics, the ESEEM spectra, and the hyperfine couplings reflect a similar interaction between the iron-sulfur protein and the quinone or stigmatellin and that the N(delta) involved is that of a histidine (equivalent to His-161 in the chicken mitochondrial complex) that forms both a ligand to the cluster and a hydrogen bond with a carbonyl oxygen atom of the Q(o)-site occupant.     

Autoantibody systems in rheumatoid arthritis: specificity, sensitivity and diagnostic value

The diagnosis of rheumatoid arthritis (RA) is primarily based on clinical symptoms, so it is often difficult to diagnose RA in very early stages of the disease. A disease-specific autoantibody that could be used as a serological marker would therefore be very useful. Most autoimmune diseases are characterized by a polyclonal B-cell response targeting multiple autoantigens. These immune responses are often not specific for a single disease. In this review, the most important autoantibody/autoantigen systems associated with RA are described and their utility as a diagnostic and prognostic tool, including their specificity, sensitivity and practical application, is discussed. We conclude that, at present, the antibody response directed to citrullinated antigens has the most valuable diagnostic and prognostic potential for RA.     

Splinting or surgery for carpal tunnel syndrome? Design of a randomized controlled trial [ISRCTN18853827]

Background  

Carpal tunnel syndrome is a common disorder, which can be treated with surgery or conservative options. However, there is insufficient evidence and no consensus among physicians with regard to the preferred treatment for carpal tunnel syndrome. Therefore, a randomized controlled trial is conducted to compare the short- and long-term efficacy of surgery and splinting in patients with carpal tunnel syndrome. An attempt is also made to avoid the (methodological) limitations encountered in earlier trials on the efficacy of various treatment options for carpal tunnel syndrome.     

The non-photochemical reduction of plastoquinone in leaves

Although it is generally assumed that the plastoquinone pool of thylakoid membranes in leaves of higher plants is rapidly oxidized upon darkening, this is often not the case. A multiflash kinetic fluorimeter was used to monitor the redox state of the plastoquinone pool in leaves. It was found that in many species of plants, particularly those using the NAD-malic enzyme C₄ system of photosynthesis, the pool actually became more reduced following a light to dark transition. In some Amaranthus species, plastoquinone remained reduced in the dark for several hours. Far red light, which preferentially drives Photosystem I turnover, could effectively oxidize the plastoquinone pool. Plastoquinone was re-reduced in the dark within a few seconds when far red illumination was removed. The underlying mechanism of the dark reduction of the plastoquinone pool is still uncertain but may involve chlororespiratory activity.Abbreviations apparent F_o observed fluorescence yield after dark adaptation - F_m maximum fluorescence when all Q_A is fully reduced - F_o minimum fluorescence yield when Q_A is fully oxidized and non-photochemical quenching is fully relaxed - F_s steady state fluorescence yield - PPFD photosynthetic photon flux density - PQ plastoquinone - Q_A primary quinone acceptor of the Photosystem II reaction center - Q_B secondary quinone acceptor to the Photosystem II reaction center - F F_m minus F_s     

Microsatellite evolution in congeneric mammals: domestic and bighorn sheep

We compared genotypes at eight (AC)n microsatellite loci in domestic sheep (Ovis aries) and wild Rocky Mountain bighorn sheep (O. canadensis). The domestic sheep had greater genetic variation, higher allele-size variances, and larger allele sizes than the wild sheep. Accumulating evidence from higher taxonomic comparisons shows that these parameters are biased if microsatellite loci are selected in one taxon and used in another. Our results demonstrate similar biases between congeneric species. We compared standard measures of genetic variation, differentiation, and distance within and between species (H, D, FST) to newer measures based on allele-size variance (SW, SB, RST). The size-based distances better detected species-level divergence, but standard measures better distinguished allopatric populations. Empirical calibration of these measures at the subspecies level is needed to establish their useful ranges.      

The role of cytochrome b-566 in the electron-transfer chain of Rhodopseudomonas sphaeroides

Spectrophotometric, kinetic, thermodynamic and stoichiometric properties of the low-potential b-type cytochrome of chromatophores from Rhodopseudomonas sphaeroides are reported. Cytochrome b-566 has a double α-band with maxima at 559 and 566 nm. Resolution of the spectrum by full-spectral redox potentiometry showed no indication that the two peaks represent more than one component. The component titrated with E_m,7 ≈ ?80 ± 10 mV. By appropriate choice of wavelength pairs and by subtraction of the contribution due to other components, the kinetics of cytochrome b-566 absorbance changes following flash excitation have been resolved from those of other components. Time-resolved flash spectra corrected for the contributions of other components are consistent with the behavior of both peaks of the α-band as a single kinetic species. The kinetics of cytochrome b-566 in the presence of antimycin show that the reduction of this cytochrome occurred only if cytochrome b-561 was reduced before the flash, either chemically, by poising the ambient redox potential (E_h) below the E_m of cytochrome b-561 (E_m,7 ≈ 50 mV), or photochemically at higher redox potentials by a previous flash. The rate of reduction of cytochrome b-566 varied with E_h. At low E_h (approx. 0 mV) reduction on the first flash showed $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{≈ 1.25}\text{ms}$; at high E_h (approx. 180 mV) reduction on the second flash showed $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{≈ 10}\text{ms}$. In the absence of antimycin at E_h ≈ 0 mV, cytochrome b-566 was observed to become rapidly reduced ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{≈ 500 μ}\text{s}$) and then reoxidized ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{≈ 2}\text{ms}$) after a single flash. At higher redox potentials (E_h > 80 mV) no kinetic changes which could be unambiguously attributed to cytochrome b-566 were observed following a single flash. The results are interpreted in terms of a Q-cycle mechanism in which the reductant for cytochrome b-566 is the semiquinone formed on oxidation of ubiquinol from the quinone pool. The oxidation of the ubiquinol occurs by a concerted reaction in which one electron is accepted by the Rieske-type FeS center and the other by cytochrome b-566. We suggest that the kinetic characteristics may indicate a pathway for reduction of the b-type cytochromes in which cytochrome b-566 is the immediate electron acceptor and donates to cytochrome b-561 in a serial pathway. The experimental results in the presence of antimycin are compared with data from a computer simulation of the thermodynamic behavior of the chain, and the computer model is shown to provide an excellent fit.