ABSTRACT
The age of onset of sexual maturity is an important reproductive trait in chickens. In this study, we explored candidate genes associated with sexual maturity and ovary development in chickens. We performed DGE RNA-sequencing analyses of ovaries of pre-laying (P-F-O1, L-F-O1) and laying (P-F-O2, L-F-O2) hens of two sub-breeds of Ningdu Yellow chicken. A total of 3197 genes were identified in the two comparisons, and 966 and 1860 genes were detected exclusively in comparisons of P-F-O1 vs. P-F-O2 and L-F-O1 vs. L-F-O2, respectively. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that genes involved in transmembrane signaling receptor activity, cell adhesion, developmental processes, the neuroactive ligand-receptor interaction pathway, and the calcium signaling pathway were enriched in both comparisons. Genes on these pathways, including growth hormone (GH), integrin subunit beta 3 (ITGB3), thyroid stimulating hormone subunit beta (TSHB), prolactin (PRL), and transforming growth factor beta 3 (TGFB3), play indispensable roles in sexual maturity. As a gene unique to poultry, hen egg protein 21 kDa (HEP21) was chosen as the candidate gene. Differential expression and association analyses were performed. RNA-seq data and qPCR showed that HEP21 was significantly differentially expressed in pre-pubertal and pubertal ovaries. A total of 23 variations were detected in HEP21. Association analyses of single nucleotide polymorphisms (SNPs) in HEP21 and reproductive traits showed that rs315156783 was significantly related to comb height at 84 and 91 days. These results indicate that HEP21 is a candidate gene for sexual maturity in chickens. Our results contribute to a more comprehensive understanding of sexual maturity and reproduction in chickens.
ABSTRACT
The poisoning effect of PbO and PbCl2 on CeO2-TiO2 catalyst for selective catalytic reduction of NO with NH3 was investigated and compared. Both Pb species could deactivate the CeO2-TiO2 catalyst and PbO had a stronger poisoning effect than PbCl2. From the characterization results of BET, XRD, XPS, NH3-TPD and H2-TPR, it was concluded that the more serious deactivation by PbO could be ascribed to smaller BET surface area, fewer surface Ce3+ and chemisorbed oxygen, stronger interaction between PbO and CeO2-TiO2 catalyst, lower redox properties and surface acidity. The in situ DRIFT study results revealed that the NH3-SCR reaction over CeO2-TiO2 catalyst was governed by both E-R and L-H mechanisms, which wasn't changed over the Pb-poisoned samples. The greater loss of Brønsted acid sites attributed to fewer surface Ce3+ and more serious inhibition of NO oxidation to NO2 due to fewer surface chemisorbed oxygen were two key factors responsible for more serious deactivation by PbO. Furthermore, the presence of Pb species inhibited the NH3 adsorption on the Lewis acid sites, aggravating the deactivation of CeO2-TiO2 catalyst.
ABSTRACT
The effect of HCl on a CeO2-MoO3/TiO2 catalyst for the selective catalytic reduction of NO with NH3 was investigated with BET, XRD, NH3-TPD, H2-TPR, XPS and catalytic activity measurements. The results showed that HCl had an inhibiting effect on the activity of the CeO2-MoO3/TiO2 catalyst. The deactivation by HCl of the CeO2-MoO3/TiO2 catalyst could be attributed to pore blockage, weakened interaction among ceria, molybdenum and titania, reduction in surface acidity and degradation of redox ability. The Ce3+/Ce4+ redox cycle was damaged because unreactive Ce3+ in the form of CeCl3 lost the ability to be converted to active Ce4+ in the SCR reaction. In addition, a decrease in the amount of chemisorbed oxygen and the concentrations of surface Ce and Mo was also responsible for the deactivation by HCl of the CeO2-MoO3/TiO2 catalyst.
