Association between polymorphisms in the SLC27A1 gene and milk production traits in Chinese Holstein cattle

We assessed SLC27A1, a candidate gene for milk production traits in Chinese Holstein cattle. DNA was extracted from the blood of 48 top Chinese Holstein Cattle selected according to phenotypic character and mixed into DNA pool for SNP detection. We tested blood samples of these cattle for SNPs in exon 3 and the 3'-flanking region of the SLC27A1 gene by using polymerase chain reaction-single-stranded conformation polymorphism (PCR-SSCP) and DNA sequencing. We found 2 polymorphic sites: 112T>C, a synonymous mutation, in exon 3 (SNP(1)), and 64G>A in the 3'-UTR (SNP(2)). We also determined the genotypes of 330 Chinese Holstein cattle by using PCR-restriction fragment length polymorphism (RFLP). We found 3 genotypes each at SNP(1) (TT, TC, and CC) and SNP(2) (GG, GA, and AA). The association among the different genotypes at these 2 sites and milk production traits was analyzed using a least-squares procedure. The results showed that cows with genotype CC had higher milk yields than those with genotype TC (0.01 < p < 0.05). No significant difference was detected among the 3 SNP(2) genotypes in terms of milk production traits. Our results provide evidence that the C allele have potential effects on milk yield trait.     

The Dynamic Landscape of Open Chromatin during Human Cortical Neurogenesis

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Chemical synthesis and functional characterization of a new class of ceramide analogues as anti-cancer agents

Deregulation of ceramide metabolism is a hallmark of human cancer. Ceramide analogues thereby represent a new class of anti-cancer agents. We aimed at developing effective and low toxic ceramide analogues and synthesized a new class of ceramide analogues starting from l-threonine. Several analogues exhibit potent cytotoxicity against human cancer cells in vitro with IC₅₀ as low as 4.8?μM. These ceramide analogues decreased xIAP and Bcl-xL level and exhibited significant sensitization activity to overcome human cancer cell resistance to TRAIL, a cancer-selective agent that are being tested in human clinical trials. Furthermore, we determined that these ceramide analogues effectively suppress human cancer xenograft growth in vivo with no significant toxicity at the efficacious dose. Therefore, we have developed a simple and effective method to synthesize functional ceramide analogues using l-threonine as starting material and these analogues have the great potential to be further developed as anti-cancer agents in human cancer therapy.     

Partial inhibition of skeletal muscle contraction by dantrolene sodium and its modification with perchlorate and Bay K 8644.

The effects of dantrolene sodium (DAN) on the dihydropyridine receptor (DHPR) of the transverse (T) tubule voltage sensor (Ca2+ channel) was studied with single fibers from bullfrog toe muscle. Perchlorate (ClO4-), which acts selectively on the DHPR, overcame DAN-induced inhibition of twitch tension. Bay K 8644, a DHPR agonist, slowed the rate of twitch inhibition by DAN. DAN inhibited twitch tension to a greater extent in Ca(2+)-free solution than in Ringer solution or solution containing Zn2+, whereas twitch inhibition by DAN was less in caffeine-containing solution than in the control. The effects of DAN on Zn(2+)- and caffeine-treated fibers and on fibers in Ca(2+)-free solution suggest that DAN must act near the voltage sensor of the T tubule. However, differences in net twitch inhibition by DAN between control fibers and fibers potentiated by ClO4- or Bay K 8644 suggest that DAN does not bind to the same site as these potentiating agents do. The role of myoplasmic Ca2+ in DAN-induced inhibition of twitch and the effects of DAN on the mechanical threshold and membrane potential in skeletal muscle are discussed.     

The interaction between co-cultured human nucleus pulposus cells and mesenchymal stem cells in a bioactive scaffold

Mesenchymal stem cells (MSCs) can differentiate into nucleus pulposus (NP) cells upon being co-cultured with NP cells. Important growth factors and morphogens secreted by MSCs during the differentiation process also enhance the biological properties of NP cells. In this study, the interactions between human NP cells and MSCs co-cultured in different cell-ratio (100% NP, 75% NP with 25% MSCs, 50% NP with 50% MSCs, 25% NP with 75% MSCs, and 100% MSCs) in a three-dimensional gelatin/chondroitin-6-sulfate/hyaluronan tri-copolymer scaffold were examined. Results showed that the cell proliferation was increased when NP and MSCs were co-cultured. Real-time PCR and immunohistochemical staining revealed that all co-culture groups produced type II collagen which represent normal NP cells but not type I collagen secreted by degenerated NP cells. FADD expression, which modulates cell survival and extracellular matrix homeostasis, was maintained in a stable status for co-cultured groups. The cultures containing 75% NP cells with 25% MSCs showed high level of collagen production and glycosaminoglycan content. Moreover, 75% NP cells with 25% MSCs had upregulated SOX9 that contributes to the improvement in type II collagen mRNA expression and protein production. These findings showed the NP/MSC cell-ratio influenced the cell functions dramatically. The co-culture of NP/MSC cells in a bioactive scaffold is a promising treatment for intervertebral disc diseases.     

Medium optimization and structural characterization of exopolysaccharides from endophytic bacterium Paenibacillus polymyxa EJS-3

In this study, response surface methodology was employed to optimize the medium compositions for the production of exopolysaccharides (EPS) from endophytic bacterium Paenibacillus polymyxa EJS-3. Firstly, fractional factorial design was applied to evaluate the effects of different components in the medium. It was found that sucrose, yeast extract and CaCl₂ influenced significantly the production of EPS. Then, steepest ascent method and central composite design were used to optimize the concentrations of the three variables. As results, the optimal medium compositions were determined as following (g/L): sucrose 188.2, yeast extract 25.8, K₂HPO₄ 5 and CaCl₂ 0.34, with a corresponding yield of 35.26 g/L. In addition, both polysaccharide fractions (EPS-1 and EPS-2) from crude EPS were mainly composed of (2 → 6)-linked β-d-fructofuranosyl residues backbone with (2 → 1)-linked branches based on their structural characterization by FT-IR spectroscopy, methylation analysis and ¹³C NMR spectroscopy.     

All three Ca2+-binding loops of photoproteins bind calcium ions: the crystal structures of calcium-loaded apo-aequorin and apo-obelin

The crystal structures of calcium-loaded apo-aequorin and apo-obelin have been determined at resolutions 1.7A and 2.2 A, respectively. A calcium ion is observed in each of the three EF-hand loops that have the canonical calcium-binding sequence, and each is coordinated in the characteristic pentagonal bipyramidal configuration. The calcium-loaded apo-protein retain the same compact scaffold and overall fold as the unreacted photoproteins containing the bound substrate, 2-hyroperoxycoelenterazine, and also the same as the Ca2+-discharged obelin bound with product, coleneteramide. Nevertheless, there are easily discerned shifts in both helix and loop regions, and the shifts are not the same between the two proteins. It is suggested that these photoproteins to sense Ca2+ concentration transients and to produce their bioluminescence response on the millisecond timescale. A mechanism of intrastructural transmission of the calcium signal is proposed.