Uranyl photochemistry: decarboxylation of gluconic acid

In weakly acidic aqueous solutions, uranyl is able to slowly photolyze gluconic acid under ambient laboratory light (fluorescence lamps). The photolysis follows “complex formation”, resulting in the decarboxylation of gluconic acid (CH2OH(CHOH)4COOH) to form D-arabinose ((CHOH)4OCH2). A possible pathway is proposed to be the sensitized photo-oxidation, which can be described as U(VI)·CH2OH(CHOH)4COOH → U(V) + CH2OH(CHOH)3ĊHOH + CO2 + H+ and U(V) + CH2OH(CHOH)3ĊHOH + H+ → U(VI) + (CHOH)4OCH2 + H2. Also, characterization of the precipitate observed in the photolytic samples demonstrates the presence of tetravalent U, which we believe is generated by concurrent disproportionation of intermediate pentavalent U.

A 6-bp deletion in the TYRP1 gene causes the brown colouration phenotype in Chinese indigenous pigs

Brown coat colour has been described in Chinese-Tibetan, Kele, and Dahe pigs. Here, we report the identification of a causal mutation underlying the brown colouration. We performed a genome-wide association study (GWAS) on Tibetan and Kele pigs, and found that brown colours in Chinese breeds are controlled by a single locus on pig chromosome 1. By using a haplotype-sharing analysis, we refined the critical region to a 1.5-Mb interval that encompasses only one pigmentation gene: tyrosinase-related protein 1 (TYRP1). Mutation screens of sequence variants in the coding region of TYRP1 revealed a strong candidate causative mutation (c.1484_1489del). The protein-altering deletion showed complete association with the brown colouration across Chinese-Tibetan, Kele, and Dahe breeds by occurring exclusively in brown pigs (n=121) and lacking in all non-brown-coated pigs (n=745) from 27 different breeds. The findings provide the compelling evidence that brown colours in Chinese indigenous pigs are caused by the same ancestral mutation in TYRP1. To our knowledge, this study gives the first description of GWAS identifying causal mutation for a monogenic trait in the domestic pig.

Marker imputation with low-density marker panels in Dutch Holstein cattle

The availability of high-density bovine genotyping arrays made implementation of genomic selection possible in dairy cattle. Development of low-density single nucleotide polymorphism (SNP) panels will allow the extension of genomic selection to a larger portion of the population. Prediction of ungenotyped markers, called imputation, is a strategy that allows using the same low-density chips for all traits (and for different breeds). In the present study, we evaluated the accuracy of imputation with low-density genotyping arrays in the Dutch Holstein population. Five different sizes of genotyping arrays were tested, from 384 to 6,000 SNP. According to marker density, the overall allelic imputation error rate obtained with the program DAGPHASE, which relies on linkage disequilibrium and linkage, ranged from 11.7 to 2.0%, and that obtained with the program CHROMIBD, which relies on linkage and the set of all genotyped ancestors, ranged from 10.7 to 3.3%. However, imputation efficiency was influenced by the relationship between low-density and high-density genotyped animals. Animals with both parents genotyped had particularly low imputation error rates: <1% with 1,500 SNP or more. In summary, missing marker alleles can be predicted with 3 to 4% errors with approximately 1 SNP/Mb (approximately 3,000 markers). The CHROMIBD program proved more efficient than DAGPHASE only at lower marker densities or when several genotyped ancestors were available. Future studies are required to measure the effect of these imputation error rates on accuracy of genomic selection with low-density SNP panels.

Microfluidic rheology of soft colloids above and below jamming

The rheology near jamming of a suspension of soft colloidal spheres is studied using a custom microfluidic rheometer that provides the stress versus strain rate over many decades. We find non-Newtonian behavior below the jamming concentration and yield-stress behavior above it. The data may be collapsed onto two branches with critical scaling exponents that agree with expectations based on Hertzian contacts and viscous drag. These results support the conclusion that jamming is similar to a critical phase transition, but with interaction-dependent exponents.

Establishment of a porcine model for lobar lung auto-transplantation

OBJECTIVE

The aim of this study was to develop a porcine model of left single lung auto-transplantation.

METHODS

Eighteen 50-kg male domestic pigs underwent left pneumonectomy and lobar lung auto-transplantation (left lower lobe). Each animal was allocated to a perfusion protocol during surgery: group I, cold saline (n = 6); group II, cold heparin (n = 6); and group III, cold Euro-Collins (n = 6). We measured changes of partial pressure of oxygen in pulmonary vein blood (PvO(2)), partial pressure of carbon dioxide in pulmonary vein blood (PvCO(2)), lung compliance, and mean pulmonary artery pressure.

RESULTS

The postoperative survival rate was 100%. PvO(2), PvCO(2), mean pulmonary artery pressure, and lung compliance of the left lower lobe showed a significant difference between the saline and the heparin groups or the Euro-Collins group (P < .05), whereas there was no significant difference between the heparin and the Euro-Collins groups.

CONCLUSION

Compared with other species, humans and pigs show remarkable anatomical and physiological similarity. It is useful experimental animal model to evaluate pulmonary function and grafting protocols following lobar lung transplantation.

Associations between the genetic polymorphisms of MTHFR and outcomes of methotrexate treatment in rheumatoid arthritis

OBJECTIVES

To determine whether 5, 10-methylenetetrahydrofolate reductase (MTHFR) rs1801133C/T, rs1801131A/C, rs2274976A/G, rs2066462C/T genetic polymorphisms are associated with clinical response and adverse effects (AEs) of methotrexate (MTX) treatment in Chinese Han patients with rheumatoid arthritis (RA).

METHODS

One hundred and ten RA patients defined by the American College of Rheumatology (ACR) 1987 revised criteria were involved in this study. All patients were treated with low-dose MTX (10-15 mg/week) without concomitant uses of other DMARDs. Clinical response (using ACR20 criteria) and AEs were evaluated at 0, 4, 12, 16 and 24 weeks. The genotypes of MTHFR rs1801133C/T, rs1801131A/C, rs2274976A/G and rs2066462C/T were detected by real-time fluorescent quantitative PCR.

RESULTS

The allele frequency of rs1801131C in the clinical response group was higher than in the non-response group (21.0% vs. 8.1%, p<0.05), and the patients with CC or AC genotype had greater clinical response than those with AA genotype. The allele frequencies of rs1801133T and rs2274976A were higher in the group with AEs than that without AEs (56.4% vs. 37.5% and 14.9% vs. 4.2%, respectively, both p<0.05). The patients with CT or TT genotype in rs1801133 had higher risks of AEs than those with CC genotype.

CONCLUSIONS

While rs1801131A/C genetic polymorphism is associated with the clinical response, rs1801133C/T and rs2274976A/G genetic polymorphisms are associated with MTX-related AEs in the treatment of RA. This suggests individualisation is necessary to achieve optimal outcomes in MTX therapy of RA.

Development of functional nanoprobes for optical near-field characterization

Subwavelength optical imaging can be accomplished by scanning a nanoscale aperture or a nanoprobe containing a locally defined nanoscale optical source. Currently, most such methods, including various implementations of near-field scanning optical microscopy (NSOM), form near-field images by measuring the intensity of optical signals generated by optical transmission, scattering or fluorescence. Here we report the development of a nanoprobe that can extend NSOM functionalities by focusing on the dynamical aspects of light emission (such as fluorescence lifetime measurement) and nonlinear optical processes (such as second harmonic generation). Our nanoprobes consist of a silica fiber taper, a single nanowire or a nanotube, and appropriate functional nano-optical structures. The fabrication, characterization and potential applications of such nanoprobes are discussed.

Maternal and fetal tissue accumulation of selected endocrine disrupting compounds (EDCs) following exposure to sewage sludge-treated pastures before or after conception

Liver concentrations of selected pollutant classes were determined in groups of sheep fetuses and their dams, at 55 (Experiment 1) and 110 (Experiment 2) days of gestation (term = 145 d) following exposure, throughout their breeding lives and after mating, to pasture treated with either inorganic fertiliser (control, CC) or with sewage sludge (treated, TT). In a unique study designed to separate the respective contributions of environmental sources and mobilised tissue to the available EDC burden, in additional groups of animals, pollutant burdens at 110 days gestation were assessed following exposure to the respective treatments, either throughout their breeding lives until mating, but not thereafter (TC), or only between mating and slaughter (CT) (Experiment 3). With very few exceptions, maternal and fetal liver concentrations of diethylhexyl phthalate (DEHP) and selected polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDE) and polycyclic aromatic hydrocarbons (PAHs) were not significantly affected by sludge exposure in any group. In some cases, maternal and fetal tissue EDC concentrations were different but the differences were not consistent, and maternal and fetal concentrations of none of the classes of chemical were significantly correlated. It was not possible to identify a single chemical, or class of chemical, that may be responsible for previously observed physiological effects of exposure to sludge-treated pastures. It is concluded that exposure of sheep to pastures fertilised with sewage sludge was not associated with increased liver concentrations of EDCs, irrespective of the stage of development at which they were measured and of maternal tissue mobilisation and EDC release during gestation. Thus, retrospective measurements of EDC tissue burdens could not be used to accurately assess earlier fetal EDC insults.