Molecular mapping of quantitative trait loci for three kernel-related traits in maize using a double haploid population

Kernel size and kernel weight are important factors possibly involved in the determination of grain yield in maize, so identifying the genetic basis of kernel-related traits provides insights into the breeding of high-yield maize varieties. Kernel length (KL), kernel width (KW) and hundred kernel weight (HKW) were evaluated in three various planting conditions for the 240 field-grown double haploid (DH) lines derived from the single-cross hybrid Xianyu335. Variations in KL, KW and HKW were observed among DH lines, and all three traits showed a broad sense heritability of 76%. A total of 964 single nucleotide polymorphisms (SNPs) from the MaizeSNP3072 chip was utilised to create a high-density genetic map of 1546.4 cM and to identify quantitative trait loci (QTLs). Using composite interval mapping, a total of five, seven and five QTLs have been mapped for KL, KW and HKW, respectively. qkl1-2 and qkl4-1 explained 17.8% and 14.2% of the phenotypic variation in KL, respectively, and the other three QTLs contributed 3.2–4.0%. The phenotypic variation explained (PVE) of seven QTLs responsible for KW ranged from 3.3 to 9.5%. Three QTLs for HKW, qhkw1, qhkw5 and qhkw10 each explained more than 10% of the phenotypic variation, and qhkw4 and qhkw9 accounted for 3.0% and 6.0%, respectively. Due to their detection in multiple planting environments, the loci mapped here appear to be potential targets for the improvement of maize grain yield.     

Impact of Conditional miRNA126 Overexpression on Apoptosis-Resistant Endothelial Cell Production

The activation of endothelial cells is essential to repair damage caused by atherosclerosis via endothelial cell proliferation and migration. Overexpression of VEGF (vascular endothelial growth factor) and the downstream gene, B-cell lymphoma-2 (BCL-2) could result in apoptosis-resistant endothelial cells, which are responsible for aggravated hyperplasia and instable plaques generation. Previous studies have shown that miRNA126 could regulate the expression of VEGF. Here, we verified the existence of a miRNA126 binding site in VEGF’s 3’UTR. Additionally, VEGF regulated BCL-2 expression via AP1 (Activator Protein 1) binding site in BCL-2’s promoter. Next, we established an apoptosis-resistant endothelial cell line and constructed a lentiviral vector to express miRNA126 under the control of the BCL-2 promoter to investigate whether conditional expression of miRNA126 could modulate VEGF and BCL-2 expression in apoptosis-resistant endothelial cells. This lentiviral system specifically expressed miRNA126 in cells with high BCL-2 levels, downregulated VEGF expression, inhibited MAPK pathway activation and downregulated BCL-2 expression via suppression of AP1, and as a whole, reduced apoptosis-resistant endothelial cells, while the effects of miRNA126 on normal endothelial cells were relatively small. Our results demonstrate that conditional miRNA126 overexpression under the control of the downstream BCL-2 promoter provides a flexible regulatory strategy for reducing the apoptosis-resistant endothelial cells without having a significant impact on normal endothelial cells.     

Neuroprotective Effect of Chitosan Oligosaccharide on Hypoxic-Ischemic Brain Damage in Neonatal Rats

Neonatal hypoxic-ischemic brain damage (HIBD) is one of the leading causes of neonatal mortality and permanent neurological disability worldwide and the effective treatment strategies are not yet available. It has been demonstrated that Chitosan oligosaccharide (COS) exerts protective effect in vitro ischemic brain injury. However, no information is available on possible effects of COS on neonatal HIBD. To investigate the hypothesis of the potential neuroprotective effect of COS on the brain injury due to HIBD, 7-day-old Sprague–Dawley rats were treated with left carotid artery ligation followed by exposure to 8% oxygen (balanced with nitrogen) for 2.5 h at 37?°C. After COS treatment, the cerebral damage was measured by behavior tasks, 2,3,5-triphenyltetrazolium chloride(TTC), Hematoxyline-Eosin(HE), Nissl and Fluoro-Jade B(FJB)staining. In addition, the oxidative stress were assayed with ipsilateral hemisphere homogenates. Immunofluorescence staining were used to examine the activation of the astrocyte and microglia. Expression of inflammatory-related proteins were analyzed by western-blot analysis. In this study we found that administration of COS ameliorated early neurological reflex behavior, significantly reduce brain infarct volume and attenuated neuronal cell injury and degeneration. Furthermore, COS markedly decreased the level of MDA, lactic acid and increased SOD, GSH-Px and T-AOC. COS attenuated hypoxic-ischemic induced up-regulation of expressions of interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), meanwhile it dramatically increased the interleukin-10 (IL-10). These results suggest that COS exerts neuroprotection on hypoxic-ischemic brain damage in neonatal rats, it implies COS might be a potential therapeutic for the treatment of HIBD.     

Splenic gene expression profiling in White Leghorn layer inoculated with the Salmonella enterica serovar Enteritidis

Salmonella enterica serovar Enteritidis (SE) is a foodborne pathogen that can threaten human health through contaminated poultry products. Live poultry, chicken eggs and meat are primary sources of human salmonellosis. To understand the genetic resistance of egg‐type chickens in response to SE inoculation, global gene expression in the spleen of 20‐week‐old White Leghorn was measured using the Agilent 4 × 44 K chicken microarray at 7 and 14 days following SE inoculation (dpi). Results showed that there were 1363 genes significantly differentially expressed between inoculated and non‐inoculated groups at 7 dpi (I7/N7), of which 682 were up‐regulated and 681 were down‐regulated genes. By contrast, 688 differentially expressed genes were observed at 14 dpi (I14/N14), of which 371 were up‐regulated genes and 317 were down‐regulated genes. There were 33 and 28 immune‐related genes significantly differentially expressed in the comparisons of I7/N7 and I14/N14 respectively. Functional annotation revealed that several Gene Ontology (GO) terms related to immunity were significantly enriched between the inoculated and non‐inoculated groups at 14 dpi but not at 7 dpi, despite a similar number of immune‐related genes identified between I7/N7 and I14/N14. The immune response to SE inoculation changes with different time points following SE inoculation. The complicated interaction between the immune system and metabolism contributes to the immune responses to SE inoculation of egg‐type chickens at 14 dpi at the onset of lay. GC, TNFSF8, CD86, CD274, BLB1 and BLB2 play important roles in response to SE inoculation. The results from this study will deepen the current understanding of the genetic response of the egg‐type chicken to SE inoculation at the onset of egg laying.     

A new genus of Coelotinae (Araneae,Agelenidae) from southern China

One new genus of the spider subfamily Coelotinae, Flexicoelotes gen. n., with five new species is described from southern China: Flexicoelotes huyunensis sp. n. (female), Flexicoelotes jiaohanyanensis sp. n. (male and female), Flexicoelotes jinlongyanensis sp. n. (male and female), Flexicoelotes pingzhaiensis sp. n. (female), Flexicoelotes xingwangensis sp. n. (male and female).     

A New Pathway for Senescence Regulation

<正>Research concerning senescence has become a hotspot since the conception of‘cellular senescence’was put forward by Drs.Hayflick and Moorhead over five decades ago[1].Recently,a paper published in Science by Kang and colleagues,which this article aims to comment on,provides evidence of a new pathway involved in senescence[2].Senescence is a physiological and pathological process induced by numerous factors,during which cell growth ceases     

Statistical Inference Methods for Two Crossing Survival Curves: A Comparison of Methods

A common problem that is encountered in medical applications is the overall homogeneity of survival distributions when two survival curves cross each other. A survey demonstrated that under this condition, which was an obvious violation of the assumption of proportional hazard rates, the log-rank test was still used in 70% of studies. Several statistical methods have been proposed to solve this problem. However, in many applications, it is difficult to specify the types of survival differences and choose an appropriate method prior to analysis. Thus, we conducted an extensive series of Monte Carlo simulations to investigate the power and type I error rate of these procedures under various patterns of crossing survival curves with different censoring rates and distribution parameters. Our objective was to evaluate the strengths and weaknesses of tests in different situations and for various censoring rates and to recommend an appropriate test that will not fail for a wide range of applications. Simulation studies demonstrated that adaptive Neyman’s smooth tests and the two-stage procedure offer higher power and greater stability than other methods when the survival distributions cross at early, middle or late times. Even for proportional hazards, both methods maintain acceptable power compared with the log-rank test. In terms of the type I error rate, Renyi and Cramér—von Mises tests are relatively conservative, whereas the statistics of the Lin-Xu test exhibit apparent inflation as the censoring rate increases. Other tests produce results close to the nominal 0.05 level. In conclusion, adaptive Neyman’s smooth tests and the two-stage procedure are found to be the most stable and feasible approaches for a variety of situations and censoring rates. Therefore, they are applicable to a wider spectrum of alternatives compared with other tests.