BackgroundGenome-wide association studies (GWAS) have been extensively used to identify genomic regions associated with a variety of phenotypic traits in pigs. Until now, most GWAS have explored single-trait association models. Here, we conducted both single- and multi-trait GWAS and a meta-analysis for nine fatness and growth traits on 2004 pigs from four diverse populations, including a White Duroc × Erhualian F2 intercross population and Chinese Sutai, Laiwu and Erhualian populations.ResultsWe identified 44 chromosomal regions that were associated with the nine traits, including four genome-wide significant single nucleotide polymorphisms (SNPs) on SSC2 (SSC for Sus scrofa chromosome), 4, 7 and X. Compared to the single-population GWAS, the meta-analysis was less powerful for the identification of SNPs with population-specific effects but more powerful for the detection of SNPs with population-shared effects. Multiple-trait analysis reduced the power to detect trait-specific SNPs but significantly enhanced the power to identify common SNPs across traits. The SNP on SSC7 had pleiotropic effects on the nine traits in the F2 and Erhualian populations. Another pleiotropic SNP was observed on SSCX for these traits in the F2 and Sutai populations. Both population-specific and shared SNPs were identified in this study, thus reflecting the complex genetic architecture of pig growth and fatness traits.ConclusionsWe demonstrate that the multi-trait method and the meta-analysis on multiple populations can be used to increase the power of GWAS. The two significant SNPs on SSC7 and X had pleiotropic effects in the F2, Erhualian and Sutai populations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12711-017-0295-4) contains supplementary material, which is available to authorized users.

Magnetically responsive heparin-immobilized cellulose nanofiber composites were synthesized by wet-wet electrospinning from a nonvolatile, room-temperature ionic liquid (RTIL), 1-methyl-3-methylimidazolium acetate ([EMIM]-[Ac]), into an aqueous coagulation bath. Superparamagnetic magnetite (Fe 3 O 4 ) nanoparticles were incorporated into the fibers to enable the manipulation of both dry and wet nanofiber membranes with an external magnetic field. Three synthetic routes were developed to prepare three distinct types of nanocomposite fibers: cellulose-Fe 3 O 4 −heparin monofilament fibers, cellulose-Fe 3 O 4 −heparin core−shell fibers with heparin covalently immobilized on the fiber surface, and cellulose -Fe 3 O 4 core−shell fibers with heparin physically immobilized on the fiber surface. These nanocomposite fibers were characterized by electron microscopy to confirm their coaxial structure and the fiber dimensions (fiber diameter 0.2−2.0 μm with 0.1−1.1 μm core diameter). Thermogravimetric analysis, liquid chromatography−mass spectrometry, Fourier transform infrared and X-ray diffraction spectroscopy provided detailed compositional analysis for these nanocomposite fibers, confirming the presence of each component and the surface accessibility of the heparin. The anticoagulant activity of immobilized heparin on the nanocomposite fiber surfaces was evaluated and confirmed by antifactor Xa and antifactor IIa assays.

Various polyunsaturated fatty acids, especially gamma-linolenic acid (GLA), inhibit the growth of a variety of tumor cells. Some evidence indicates that polyunsaturated fatty acid can kill cells by apoptosis. In the current study, we tested the apoptotic effect of GLA on human chronic myelogenous leukemia K562 cells. GLA induced K562 cell death in a dose-dependent manner. Typical apoptotic nuclei were shown by staining of K562 cells with DNA-binding fluorochrome Hoechst 33342, characterized by chromatin condensation and nuclear fragmentation. Flow cytometric analysis also demonstrated that GLA caused dose-dependent apoptosis of K562 cells. The apoptosis could be inhibited by a pancaspase inhibitor (z-VAD-fmk), suggesting the involvement of caspases. Further, release of cytochrome c, activation of caspase-3 and cleavage of PARP were found in GLA-induced apoptosis. GLA treatment could also elevate lipid peroxidation in K562 cells, and antioxidant alpha-tocopherol could reverse the cytotoxicity of GLA. The saturated fatty acid SA, which did not exhibit significant increase in lipid peroxidation, also did not induce cytotoxicity. Intracellular GSH was also determined, and there was no marked change of GSH levels in cells after incubation with GLA compared with the control. These results demonstrate that GLA could induce apoptosis in K562 cells. Apoptosis is mediated by release of cytochrome c, activation of caspase-3. Lipid peroxidation may play a role in GLA cytotoxicity.

Poly(glycerol sebacate) (PGS) has increasingly become a desirable biomaterial due to its elastic mechanical properties, biodegradability, and biocompatibility. Here, we report microfibrous core–shell mats of polycaprolactone (PCL)–PGS prepared using wet–wet coaxial electrospinning. The anticoagulant heparin was immobilized onto the surface of these electrospun fiber mats, and they were evaluated for their chemical, mechanical, and biological properties. The core–shell structure of PCL–PGS provided tunable degradation and mechanical properties. The slowly degrading PCL provided structural integrity, and the fast degrading PGS component increased fiber elasticity. Young’s modulus of PCL–PGS ranged from 5.6 to 15.7 MPa. The ultimate tensile stress ranged from 2.0 to 2.9 MPa, and these fibers showed elongation from 290 to 900%. The addition of PGS and grafting of heparin improved the attachment and proliferation of human umbilical vein endothelial cells. Core–shell PCL–PGS fibers demonstrate improved performance as three-dimensional fibrous mats for potential tissue-engineering applications.

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