Genetic Mapping of Quantitative Trait Loci Underlying Flowering Time in Chrysanthemum (Chrysanthemum morifolium)

Flowering time is an important trait in chrysanthemum, but its genetic basis remains poorly understood. An intra-specific mapping population bred from the cross between the autumn-flowering cultivar ‘Yuhualuoying’ and the summer-flowering ‘Aoyunhanxiao’ was used to determine the number and relative effect of QTL segregating for five measures of flowering time. From flowering time data recorded over two consecutive seasons, 35 additive QTL were detected, each explaining between 5.8% and 22.7% of the overall phenotypic variance. Of these, 13 were detected in both years. Nine genomic regions harboring QTL for at least two of the five traits were identified. Ten pairs of loci epistatically determined the flowering time, but their contribution to the overall phenotypic variance was less than for the additive QTL. The results suggest that flowering time in chrysanthemum is principally governed by main effect QTL but that epistasis also contributes to the genetic architecture of the trait, and the major QTL identified herein are useful in our ongoing efforts to streamline the improvement of chrysanthemum via the use of molecular methodology.     

Temperature Sensitivity and Basal Rate of Soil Respiration and Their Determinants in Temperate Forests of North China

The basal respiration rate at 10°C (R₁₀) and the temperature sensitivity of soil respiration (Q₁₀) are two premier parameters in predicting the instantaneous rate of soil respiration at a given temperature. However, the mechanisms underlying the spatial variations in R₁₀ and Q₁₀ are not quite clear. R₁₀ and Q₁₀ were calculated using an exponential function with measured soil respiration and soil temperature for 11 mixed conifer-broadleaved forest stands and nine broadleaved forest stands at a catchment scale. The mean values of R₁₀ were 1.83 µmol CO₂ m⁻² s⁻¹ and 2.01 µmol CO₂ m⁻² s⁻¹, the mean values of Q₁₀ were 3.40 and 3.79, respectively, for mixed and broadleaved forest types. Forest type did not influence the two model parameters, but determinants of R₁₀ and Q₁₀ varied between the two forest types. In mixed forest stands, R₁₀ decreased greatly with the ratio of coniferous to broadleaved tree species; whereas it sharply increased with the soil temperature range and the variations in soil organic carbon (SOC), and soil total nitrogen (TN). Q₁₀ was positively correlated with the spatial variances of herb-layer carbon stock and soil bulk density, and negatively with soil C/N ratio. In broadleaved forest stands, R₁₀ was markedly affected by basal area and the variations in shrub carbon stock and soil phosphorus (P) content; the value of Q₁₀ largely depended on soil pH and the variations of SOC and TN. 51% of variations in both R₁₀ and Q₁₀ can be accounted for jointly by five biophysical variables, of which the variation in soil bulk density played an overwhelming role in determining the amplitude of variations in soil basal respiration rates in temperate forests. Overall, it was concluded that soil respiration of temperate forests was largely dependent on soil physical properties when temperature kept quite low.     

Distribution of 2-kb miniplasmid pBMB2062 from Bacillus thuringiensis kurstaki YBT-1520 strain in Bacillus species

A multi-copy and small plasmid pBMB2062 from Bacillus thuringiensis kurstaki YBT-1520 strain was cloned and characterized and its distribution was analyzed using dot-blot analysis with the ORF1 fragment as a probe. Bacillus species of 84 serotypes were evaluated. The pBMB2062 plasmid was found to be present in commercial B. thuringiensis kurstaki (H3abc) and aizawai (H7) insecticides of various serotypes, and one Bacillus cereus UW85 strain (produced Zwittermicin fungicide and Cry toxin synergist). The sequences of 7 pBMB2062-like plasmids from randomly selected Bacillus species (positive signal in the dot-blot analysis) were highly conserved. Two open reading frames (ORFs), ORF1 and ORF2, were present in this plasmid. ORF1 was found to be necessary for plasmid replication, whereas ORF2 did not play a role in replication or stability. Based on its sequence homology, ORF2 was a putative solitary antitoxin. Furthermore, the copy number of the replicon of pBMB2062 was higher than those of ori1030 and ori44 based on the thermogenic data, and ori2062 could drive the stable replication of a recombinant plasmid (11 kb total size) in B. thuringiensis.     

GSTP1 Ile105Val Polymorphism and Prostate Cancer Risk: Evidence from a Meta-Analysis

Background

Glutathione S-transferase P1 (GSTP1) is thought to be involved in the detoxification of reactive carcinogen metabolites. Numerous epidemiological studies have evaluated the association of GSTP1 Ile105Val polymorphism with the risk of prostate cancer. However, the results remain inconclusive. To derive a more precise estimation, a meta-analysis was performed.

Methodology/Principal Findings

A comprehensive search was conducted to identify the eligible studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the relationship. The overall association was not significant (Val/Val vs. Ile/Ile OR = 1.06, 95% CI = 0.90–1.25, P = 0.50; Val/Val vs. Val/Ile+Ile/Ile: OR = 1.07, 95% CI = 0.91–1.25, P = 0.44). In subgroup analyses by ethnicity and prostate cancer grade, the similar results were observed. However, in stratified analysis by clinical stage, we found a significant association with low-stage prostate cancer (Val/Val vs. Ile/Ile: OR = 2.70, 95% CI = 1.73–4.22, P<0.001; Val/Val vs. Val/Ile+Ile/Ile: OR = 2.14, 95% CI = 1.38–3.33, P = 0.001). Moreover, there was no statistically significant evidence of multiplicative interactions neither between the GSTP1 Ile105Val polymorphism and GSTM1, nor between smoking status and GSTP1 on prostate cancer risk.

Conclusions

This meta-analysis showed that GSTP1 Ile105Val polymorphism might not be significantly associated with overall prostate cancer risk. Further stratified analyses showed a significant association with low-stage prostate cancer.     

Hemoglobin Levels and Weaning Outcome of Mechanical Ventilation in Difficult-To-Wean Patients: A Retrospective Cohort Study

Introduction

The effect of hemoglobin levels on the weaning outcomes of mechanically ventilated patients remains under debate, particularly for the patients with difficult weaning. This study aims to evaluate the effect of hemoglobin levels on weaning outcomes in difficult-to-wean patients.

Methods

This retrospective cohort study was conducted in a university-affiliated teaching hospital in Taiwan. Patients who fulfilled the criteria of difficult weaning were enrolled. Medical records were reviewed to obtain data on hemograms, biochemistry tests, transfusion records, comorbidities and weaning outcome. The association between hemoglobin levels and 30-day weaning outcomes was evaluated using a logistic regression model.

Results

A total of 751 patients received mechanical ventilation during the study period, 138 of whom fulfilled the criteria of difficult weaning. Compared with the patients whose hemoglobin was <8 g/dL, those with higher hemoglobin levels were more likely to be successfully weaned (odds ratio [OR], 3.69; 95% CI, 1.22–11.15 for hemoglobin 8–10 g/dL and OR, 4.16, 95% CI, 1.30–13.29 for hemoglobin >10 g/dL). Multivariate analysis showed that the odds ratio for weaning success remained significant for hemoglobin levels of 8–10 g/dL (adjusted OR, 3.3; 95% CI, 1.07–10.15) with borderline significance for hemoglobin level > 10 g/dL (adjusted OR, 2.95, 95% CI, 0.88–9.96).

Conclusions

Hemoglobin level is independently associated with weaning outcome in difficult-to-wean patients. Further studies are needed to evaluate whether a restrictive transfusion trigger for acute critical illness is also appropriate for such patients.     

Nicotinamide increases the sensitivity of chronic myeloid leukemia cells to doxorubicin via the inhibition of SIRT1

The NAD-dependent deacetylase Sirtuin 1 (SIRT1) plays a vital role in leukemogenesis. Nicotinamide (NAM) is the principal NAD⁺ precursor and a noncompetitive inhibitor of SIRT1. In our study, we showed that NAM enhanced the sensitivity of chronic myeloid leukemia (CML) to doxorubicin (DOX) via SIRT1. We found that SIRT1 high expression in CML patients was associated with disease progression and drug resistance. Exogenous NAM efficiently repressed the deacetylation activity of SIRT1 and induced the apoptosis of DOX-resistant K562 cells (K562R) in a dose-dependent manner. Notably, the combination of NAM and DOX significantly inhibited tumor cell proliferation and induced cell apoptosis. The knockdown of SIRT1 in K562R cells enhanced NAM+DOX-induced apoptosis. SIRT1 rescue in K562R reduced the NAM+DOX-induced apoptosis. Mechanistically, the combinatory treatment significantly increased the cleavage of caspase-3 and PARP in K562R in vitro and in vivo. These results suggest the potential role of NAM in increasing the sensitivity of CML to DOX via the inhibition of SIRT1.     

Mass spectrometry imaging: An emerging technology for the analysis of metabolites in insects

Mass spectrometry imaging (MSI) can visualize the composition, abundance, and spatial distribution of molecules in tissues or cells, which has been widely used in the research of life science. Insects, especially the agricultural pests, have received a great deal of interests from the scientists in biodiversity and food security. This review introduces the major characteristics of MSI, summarizes its application to the investigation of insect endogenous metabolites, exogenous metabolites, and the spatiotemporal changes of metabolites between insects and plants, and discusses its shortfalls and perspectives. The significance of these concerns is beneficial for future insect research such as physiology and metabolism.     

NADPH缺陷型Corynebacterium glutamicum重组菌株的构建及其性能分析

[目的]改造谷氨酸棒杆菌(Corynebacterium glutamicum)中NADPH合成途径,阻断胞内NADPH的合成,获得1株NADPH营养缺陷型菌株。[方法]通过失活L-赖氨酸高产菌C. glutamicum Lys-χ中葡萄糖-6-磷酸脱氢酶(Zwf)和苹果酸酶(MalE)并将NADP~+依赖型异柠檬酸脱氢酶(NADP~+-Icdcg)替换成变形链球菌(Streptococcus mutans)中的NAD~+-Icdsm,阻断胞内NADPH的合成。随后结合辅因子工程,引入大肠杆菌(Escherichia coli)中膜结合吡啶核苷酸转氢酶(PntAB)并通过不同强度启动子控制PntAB的表达水平。最后,分析不同重组菌中胞内氧化还原水平和L-赖氨酸生产强度的变化。[结果]重组菌C.glutamicum Lys-χΔZMI_(Cg)::I_(Sm)(即Lys-x1)胞内检测不到NADPH,为1株NADPH营养缺陷型菌株。该重组菌只在以葡萄糖酸为碳源的基础培养基中生长和积累L-赖氨酸,而以葡萄糖、丙酮酸、α-酮戊二酸和草酰乙酸为碳源时无法生长。此外,表达E.coli中的PntAB可回补重组菌Lys-χ1胞内NADPH的水平,但由于不同强度启动子控制PntAB表达水平不同,重组菌胞内NADPH水平也不同,并影响L-赖氨酸的生产强度。[结论]重组菌Lys-χ1可作为有效的底盘细胞,用于考察不同的NADPH再生策略,获得不同胞内NADPH水平的重组菌株,为进一步阐明NADPH调控微生物细胞生理代谢功能的机制提供研究基础。