Effect of fermentation bed on bacterial growth in the fermentation mattress material and cecum of ducks.

The composition of microorganisms in the gastrointestinal tract is closely related to the intestinal microenvironments and the exterior growth environments of host. In this study, 16S rDNA sequencing technology was adopted to investigate the influence of fermentation bed on the cecum microorganisms of ducks. Two feeding density treatment groups were set up, including group A (n = 4brids/m2) and group B (n = 6brids/m2). Samples were collected from the intermediate core fermentation layer (10-20 cm) of the fermented mattress materials and from the intestinal contents of ducks at 4, 6 and 8 weeks, respectively. Results showed that Bacteroidetes (20.12-27.17%) and Ruminococcaceae UCG-014 (2.97-10.1%) were the predominant microorganisms in duck cecum, while the Truepera (5.08-6.29%), Pricia (4.44-5.44%) and Luteimonas (3.62-4.99%) were the dominant microorganisms in fermentation mattress material. The cecum bacteria exhibited great difference among different growth periods of the ducks. Increasing the stocking density of ducks had a negative effect on the beneficial bacteria in the cecum. The microbial populations in fermentation mattress material were very different from that in the cecal. In summary, our findings can provide a scientific data for the rational use of fermentation bed feeding mode in poultry production.

Mitofusin-2 is required for mouse oocyte meiotic maturation.

Mitofusin-2 (Mfn2) is essential for embryonic development, anti-apoptotic events, protection against free radical-induced lesions, and mitochondrial fusion in many cells. However, little is known about its mechanism and function during oocyte maturation. In this study, we found that Mfn2 was expressed in the cytoplasm during different stages of mouse oocyte maturation. Mfn2 was mainly associated with α-tubulin during oocyte maturation. Knockdown of Mfn2 by specific siRNA injection into oocytes caused the mitochondrial morphology and quantity to change, resulting in severely defective spindles and misaligned chromosomes. This led to metaphase I arrest and the failure of first polar body extrusion. Furthermore, Mfn2 depletion from GV stage oocytes caused the redistribution of p38 MAPK in oocyte cytoplasm. These findings provide insights into potential mechanisms of Mfn2-mediated cellular alterations, which may have significant implications for oocyte maturation.

Target disruption of ribosomal protein pNO40 accelerates aging and impairs osteogenic differentiation of mesenchymal stem cells.

pNO40/PS1D, a novel nucleolar protein, has been characterized as a core protein of eukaryotic 60S ribosome and at least two splicing forms of pNO40 mRNAs with alternative starting sites have been identified. Through production of knockout (ko) mice with either exon 2 (△E2), exon 4 (△E4) or △E2+E4 targeted disruption we identified a cryptic splicing product occurring in the ko tissues examined which in general cannot be observed in regular RT-PCR detection of wild-type (wt) animals. Among ko animals, △E4 null embryos exhibited prominent senescence-associated ß-galactosidase (SA-ß-gal) staining, a marker for senescent cells, in notochord, forelimbs and heart while bone marrow-derived mesenchymal stem cells (MSCs) from △E4 null mice developed accelerated aging and osteogenic differentiation defects compared to those from wt and other isoform mutant mice. Examination of the causal relationship between pNO40 deficiency and MSC-accelerated aging revealed △E4 null disruption in MSCs elicits high levels of ROS and elevated expression levels of p16 and Rb but not p53. Further analysis with iTraq identified CYP1B1, a component of the cytochrome p450 system, as a potential molecule mediating ROS generation in pNO40 deficient MSCs. We herein established a mouse model of MSC aging through pNO40-targeted depletion and demonstrated the effects of loss of pNO40 on bone homeostasis.

Transcriptional Profiling Identifies Location-Specific and Breed-Specific Differentially Expressed Genes in Embryonic Myogenesis in Anas Platyrhynchos.

Skeletal muscle growth and development are highly orchestrated processes involving significant changes in gene expressions. Differences in the location-specific and breed-specific genes and pathways involved have important implications for meat productions and meat quality. Here, RNA-Seq was performed to identify differences in the muscle deposition between two muscle locations and two duck breeds for functional genomics studies. To achieve those goals, skeletal muscle samples were collected from the leg muscle (LM) and the pectoral muscle (PM) of two genetically different duck breeds, Heiwu duck (H) and Peking duck (P), at embryonic 15 days. Functional genomics studies were performed in two experiments: Experiment 1 directly compared the location-specific genes between PM and LM, and Experiment 2 compared the two breeds (H and P) at the same developmental stage (embryonic 15 days). Almost 13 million clean reads were generated using Illumina technology (Novogene, Beijing, China) on each library, and more than 70% of the reads mapped to the Peking duck (Anas platyrhynchos) genome. A total of 168 genes were differentially expressed between the two locations analyzed in Experiment 1, whereas only 8 genes were differentially expressed when comparing the same location between two breeds in Experiment 2. Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes pathways (KEGG) were used to functionally annotate DEGs (differentially expression genes). The DEGs identified in Experiment 1 were mainly involved in focal adhesion, the PI3K-Akt signaling pathway and ECM-receptor interaction pathways (corrected P-value<0.05). In Experiment 2, the DEGs were associated with only the ribosome signaling pathway (corrected P-value<0.05). In addition, quantitative real-time PCR was used to confirm 15 of the differentially expressed genes originally detected by RNA-Seq. A comparative transcript analysis of the leg and pectoral muscles of two duck breeds not only improves our understanding of the location-specific and breed-specific genes and pathways but also provides some candidate molecular targets for increasing muscle products and meat quality by genetic control.

Gene expression patterns, and protein metabolic and histological analyses for muscle development in Peking duck.

In this study, we aimed to use duck breast muscle and leg muscle, the 2 main productive muscle organs, as a model to elucidate the molecular mechanism controlling how the 2 muscles have different deposition capabilities, and to analyze the mechanisms facilitating duck muscle development posthatching. Peking duck breast muscle and leg muscle were collected 3, 7, and 16 wk posthatching. The morphology of the myofibers was observed by paraffin sectioning the muscles. The expression of genes involved in protein metabolism [mammalian target of rapamycin (mTOR), RPS6-p70-protein kinase (S6K), forkhead box O1 (FoxO1), muscle RING finger 1 (MuRF1), and atrogin-1 (MAFbx)] was detected using real-time quantitative PCR and Western blot assays, and the results indicated that breast muscle had a stronger capacity for both protein synthesis and protein degradation compared with leg muscle. Satellite cell frequency declined during muscle development in both tissues, and the expression of Pax3/7, satellite cell marker genes, was not significantly different between breast muscle and leg muscle. No notable apoptosis was observed in either tissue. The results of this study suggest that protein metabolism signaling is the main reason promoting duck skeletal muscle mass gain.

Transgenic mice expressing mutant Pinin exhibit muscular dystrophy, nebulin deficiency and elevated expression of slow-type muscle fiber genes.

Pinin (Pnn) is a nuclear speckle-associated SR-like protein. The N-terminal region of the Pnn protein sequence is highly conserved from mammals to insects, but the C-terminal RS domain-containing region is absent in lower species. The N-terminal coiled-coil domain (CCD) is, therefore, of interest not only from a functional point of view, but also from an evolutionarily standpoint. To explore the biological role of the Pnn CCD in a physiological context, we generated transgenic mice overexpressing Pnn mutant in skeletal muscle. We found that overexpression of the CCD reduces endogenous Pnn expression in cultured cell lines as well as in transgenic skeletal muscle fibers. Pnn mutant mice exhibited reduced body mass and impaired muscle function during development. Mutant skeletal muscles show dystrophic histological features with muscle fibers heavily loaded with centrally located myonuclei. Expression profiling and pathway analysis identified over-representation of genes in gene categories associated with muscle contraction, specifically those related to slow type fiber. In addition nebulin (NEB) expression level is repressed in Pnn mutant skeletal muscle. We conclude that Pnn downregulation in skeletal muscle causes a muscular dystrophic phenotype associated with NEB deficiency and the CCD domain is incapable of replacing full length Pnn in terms of functional capacity.

A theoretical study on reductive debromination of polybrominated diphenyl ethers.

Recent progress has been made in the reductive debromination of polybrominated diphenyl ethers (PBDEs) by nanoscale zero-valent iron (nZVI). To better understand the mechanism of this reaction, seven selected BDE congeners and their anions were investigated at the density functional theory (DFT) level using four different methods, including B3LYP/6-31G(d), B3LYP/6-31+G(d), B3LYP/6-31G(d,p) and B3LYP/6-311G(d,p). The cleaved C-Br bonds observed in the equilibrium structures of anionic PBDEs were adopted as the probe of the susceptible debromination position of PBDEs in the presence of nZVI, and the proposed major reaction pathways based on our calculations can satisfactorily conform to the reported experimental results. The debromination preference is theoretically evaluated as meta-Br > ortho-Br > para-Br. In addition, both the calculated frontier orbital energies and adiabatic electronic affinities were found to be highly related to their experimental reductive debromination rate constants. The highest linear regression coefficient was observed in the case using the energy of lowest unoccupied molecular orbital as the molecular descriptor obtained from B3LYP/6-31G(d) (R(2) = 0.961, n = 7) or B3LYP/6-31G(d,p) (R(2) = 0.961, n = 7). The results clearly showed the evidence of an electron transfer mechanism associated with this reductive debromination reaction.

Differential regulation of the human CYP11A1 promoter in mouse brain and adrenals.

CYP11A1 encodes the first enzyme of steroid biosynthesis, cytochrome P450scc. The expression of CYP11A1 in the nervous system allows neurosteroids to be synthesized de novo. In the classic steroidogenic tissues, adrenals and gonads, the key regulator controlling CYP11A1 expression is steroidogenic factor-1 (SF-1), but the transcriptional regulation of CYP11A1 in the brain is unclear. We recently used the 4.4-kb regulatory region of the human CYP11A1 gene to drive Cre recombinase expression in the diencephalon and midbrain. In this study, we characterized the regional-specific expression of Cre reporter in the SCC-Cre transgenic brain using a transient Cre/ROSA26R transgenic system. Mutation of either the upstream or proximal SF-1 binding site did not affect brain CYP11A1 promoter activity. The upstream SF-1 binding site, however, is required for CYP11A1 promoter function in the embryonic adrenals. The 3.8-kb promoter, like the 4.4-kb length promoter, directed Cre expression in the diencephalon, midbrain and olfactory epithelium, whereas Cre expression controlled by the 2.7-kb promoter was only observed in the caudal part of midbrain. This suggests that the 5'-flanking region between 3.8 and 2.7 kb contains a crucial element for activation of CYP11A1 promoter in the diencephalon, olfactory epithelium and the anterior part of midbrain. Thus we have identified regions of the promoter that control CYP11A1 expression in the brain and embryonic adrenals.

[Study on the mechanism of fluorescence quenching of pyridine by bisazafulleroid[60] derivative and its electrochemical property].

The mechanism of the fluorescence quenching of pyridine by bisazafulleroid[60] derivative (eddy2) was discussed. When the C60 and eddy2 were added into pyridine respectively, the intensity of 426.27 nm emission peak of pyridine decreased obviously and shifted towards shorter wavelength, a typical quenching phenomenon. The fluorescence quenching of eddy2-pyridine is caused by the static quenching process resulting from the formation of charge-translated complex between molecules. The dissociation constant of eddy2 from pyridine is K(D) = 2.28 x 10(-6) (mol x L(-1)). The combination constant of eddy2 is Ks = 4.39 x 10(-5) (L x mol(-1)). The electrochemical properties of eddy2 were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) on a glassy carbon electrode in a mixed solvent of toluene and acetonitrile. The first three reduction waves for eddy2 shift to more positive than that for C60, indicating the electroreduction of eddy2 is easier than that of C60.

[Determination of trace lead in Chinese medicinal materials by GFAAS with PdCl2 as a matrix modifier].

A method for the determination of lead in Chinese medicinal materials by GFAAS with PdCl2 as a matrix modifier was established. By comparing PdCl2 with NH4H2PO4 in improving effect on the determination of Pb, the dosage of PdCl2, acidity of medium, interference of coexistent ion, recovery of the method, precision of the method, and the detection limit were checked. The programmed temperature of graphite furnace was optimized. The results show that the improving effect of PdCl2 on Pb determination is better than that of NH4H2PO4. The dosage of PdCl2 is 0.3 microg. The best medium should be 1.0% HCl. The three kinds of acids, 0.4% H2SO4, 1.0% HClO4 and 1.8% HCl, did not weaken the signal of lead. The recovery of the method is 90%-104% and the precision is < 5.0%. The characteristic mass is 8.5 pg. The detection limit is 0.066 mg x kg(-1). It is concluded that the method is simple, sensitive, accurate and credible, and can be used widely.