Stable reference gene selection for quantitative real-time PCR normalization in passion fruit (Passiflora edulis Sims.).

BACKGROUND: Passiflora edulis is a tropical fruit with high nutrient and medicinal values that is widely planted in southern China. However, the molecular biology of P. edulis has not been well studied. There are few reports regarding the choice of reference genes for gene expression studies of passion fruit. METHODS AND RESULTS: By using three algorithms, implemented in geNorm, NormFinder and BestKeeper, we have selected ten candidate reference genes to explore their transcriptional expression stability in various tissues and under cold stress conditions. EF1 and HIS were stably expressed in five tissues. Ts and OTU were stably in vegetative organs. 50 S and Liom were stably in reproductive organs. The transcriptional abundance of EF1 and UBQ was stable in cold-treated and recovery treated leaf samples of P. edulis. In all samples, EF1 and Ts exhibited the highest expression stability. Evaluation of selected genes using simple statistical methods (ANOVA and post hoc analysis). Overall, EF1 emerged as the optimum reference gene for qRT-PCR normalize in P. edulis. In addition, the qRT-PCR analysis revealed that expression of ICE1 increases with the duration of cold treatment. CONCLUSIONS: In this study, we successfully screened stable reference genes from 10 candidates in P. edulis and verified the results by analyzing the expression level of ICE1. The results provide reliable and effective reference genes for future research on gene expression analysis in P. edulis, and lay a foundation for follow-up research on functional genes in P. edulis.

Stereoselective Synthesis of (±)-Cephanolide B.

A concise and stereoselective total synthesis of (±)-cephanolide B was achieved in 15 steps. The key steps in the synthesis were as follows: (i) an intermolecular Diels-Alder reaction followed by lactonization to form the oxabicyclo[2.2.2]octane DE ring; (ii) a tandem reaction, featuring an intramolecular Pauson-Khand reaction, a 6π-electrocyclization, and an oxidative aromatization by O2, to construct the ABC-tricyclic rings (6-5-6); and (iii) a phthaloyl peroxide-mediated arene oxygenation to install the C-13 phenol group.

Photoredox-Catalyzed Isomerization of Highly Substituted Allylic Alcohols by C-H Bond Activation.

Photoredox-catalyzed isomerization of γ-carbonyl-substituted allylic alcohols to their corresponding carbonyl compounds was achieved for the first time by C-H bond activation. This catalytic redox-neutral process resulted in the synthesis of 1,4-dicarbonyl compounds. Notably, allylic alcohols bearing tetrasubstituted olefins can also be transformed into their corresponding carbonyl compounds. Density functional theory calculations show that the carbonyl group at the γ-position of allylic alcohols are beneficial to the formation of their corresponding allylic alcohol radicals with high vertical electron affinity, which contributes to the completion of the photoredox catalytic cycle.

Exploring the adaptive mechanism of Passiflora edulis in karst areas via an integrative analysis of nutrient elements and transcriptional profiles.

BACKGROUND: Passiflora edulis, known as passion fruit and native to South America, is now widely cultivated throughout southern China for its edible value, medicinal efficacy and ornamental properties. We have developed a cold-tolerant variety of P. edulis ('Pingtang 1') that can survive subzero temperatures and is highly adaptable in Karst areas. In this study, cuttings of 'Pingtang 1' were cultivated in a limestone (L) rocky desertification area and a sandy dolomite (D) rock desertification area. Changes in nutrient elements in both the soils and plants were revealed in the two plots. Moreover, RNA sequencing (RNA-Seq) was performed to profile the root transcriptomes for further exploration of nutrient adaptative mechanism of Passiflora edulis in Karst regions. RESULTS: In this study, a total of, 244,705,162 clean reads were generated from four cDNA libraries and assembled into 84,198 unigenes, of which 56,962 were annotated by publicly available databases. Transcriptome profiles were generated, and 1314 unigenes (531 upregulated and 801 downregulated) were significantly differentially expressed between the L and D root cDNA libraries (L_R and D_R, respectively); these profiles provide a global overview of the gene expression patterns associated with P. edulis adaptability to Karst soils. Most unigenes including a number of differentially expressed genes (DEGs) were involved in nutrient element uptake, utilization, signal regulation. And DEGs enriched in KEGG pathways of plant hormone signal transduction, phenylpropanoid biosynthesis, and biosynthesis of unsaturated fatty acids were significantly expressed. CONCLUSION: These results could contribute to better understanding the adaptation of this species to environmental stress and thus enhance the potential for successfully introducing and commercially deploying P. edulis.

Ultrafiltration for the Determination of Cu Complexed with Dissolved Organic Matters of Different Molecular Weight from a Eutrophic River, China.

The molecular weight of dissolved organic matter (DOM) is one of the essential factors controlling the properties of metal complexes. A continuous ultrafiltration experiment was designed to study the properties of Cu complexes with different molecular weights in a river before and after eutrophication. The results showed that the concentration of DOM increased from 26.47 to 38.20 mg/L during the eutrophication process, however, DOM was still dominated by the small molecular weight fraction before and after eutrophication. The amount of Cu-DOM complexes increased with the increasing of molecular weight, however, the amounts of DOM-Cu complexes before eutrophication were higher than those after eutrophication. This is because DOM contained more -COOH and -OH before eutrophication and these functional groups are the active sites complexed with Cu.

Distribution pattern and the risks of OPCs, PHAs and PCBs in aged refuses from landfill.

Persistent organic pollutants (POPs) are the urgent risk for landfill, and should be considered before the landfill reclamation and resource. In this work, the distribution pattern of selected POPs in landfill and their ecological risks were investigated and assessed. The Σ20OCPs, Σ16PAHs and Σ19PCBs were around 157.4-329.2, 4103-19,190, and 79.1-340.3µgkg(-1) in aged refuses, with the mean value of 206.6, 8645.4, and 155.1µgkg(-1). While those in soil covers were only 6.3-75.4, 125.5-515.3 and 2.6-43.4µgkg(-1), with the mean value of 33.7, 257.7, and 24.0µgkg(-1), respectively. The maximum OPCs, PHAs and PCBs were in aged refuse with 13, 7, 10 disposal years. Whereas, the corresponding top content in soil covers were in 10, 13 and 16years, meaning that aged refuses were not the direct source for soil covers. Among 20 OCPs measured, α-HCH, δ-HCH, Dieldrin, and Endrin were presented in all aged refuses, with the mean concentration of 93.6, 52.1, 3.9 and 4.7µgkg(-1), respectively. For PAHs, PHE, FLU and PYR were the main composition, and reached to 1535, 1224, 1187µgkg(-1). The Σ7CarPAHs occupied around 33.3-49.9% of total Σ16PAHs tested, and could be used as the indictor for PAHs pollutant in landfill. PCB-5 content was around 40.7-263.3µgkg(-1) in aged refuses, and occupied around 51.5-81.8% of Σ19PCBs measured. The HCHs and DDTs in aged refuses were below the national standard GB15618-1995, and the corresponding Σ19PCBs concentrations met the standard of GB 13015-91, suggesting that aged refuse are accepted for the further utilization process.

Prolonged starvation and subsequent recovery of nitrification process in a simulated photovoltaic aeration SBR.

The ability of a new SBR (sequencing batch reactor) based on simulating photovoltaic aeration for maintaining nitrification activity under a 25-day starvation period was studied. The activity and abundance of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) and the diversity of AOB were investigated. The measured biomass decay rates were 0.017 day(-1) and 0.029 day(-1) for AOB and NOB, respectively. These decay rates correlated well with AOB and NOB population quantified by real-time PCR. The recovery of ammonia oxidation rate and nitrite oxidation rate needed 4 and 7 days, respectively, indicating that NOB was more affected than AOB by starvation conditions. According to the real-time PCR results, Nitrospira was the dominant NOB in the reactor. Phylogenetic analysis indicated that Nitrosomonas oligotropha cluster was the dominant major cluster before and after starvation. Moreover, Pareto-Lorenz evenness distribution curves were plotted to interpret the interspecies abundance of AOB; the results suggested that AOB community possessed a balanced structure with medium Fo (Functional organization). Thus, the community can potentially deal with changing environmental conditions (e.g., starvation) and preserve its functionality according to the concept of functional redundancy.

[Research on the health risk assessment of chemical pollutants in reclaimed water used for streets watering].

It is the first time for this research to utilize the method of health risk assessment. Combining with Beijing reclaimed water project, the exposure dose level and health risk to contact people are investigated and studied. The risk assessment model is built, and the exposure parameters of occupational workers and common people are provided, when reclaimed water was used for streets watering. The health risks of 19 main chemical pollutants in reclaimed water are evaluated quantificationally. The results show that the total risk caused by carcinogens is 8.47 x 10(-)6 for occupational workers and 3.78 x 10(-6) for common people.

[Exposure assessment of various reclaimed water uses].

The exposure assessment method and model of various reclaimed water uses are built combining with Beijing reclaimed water project. Firstly the daily ingesting dose and lifetime average daily dose (LADD) of exposure people are provided via field work and monitoring analysis, which could be used in health risk assessment as quantitative reference. Take park irrigation as a example, for occupational workers, the total daily ingesting dose is 0.07 L/d, LADD of disinfection by-products(DBPs) via the respiratory route is 2.8 x 10(-7) - 1.2 x 10(-5) mg x (kg x d)(-1), LADD of DBPs via the dermal route is 5.8 x 10(-8) - 2.4 x 10(-6) mg x (kg x d)(-1). For common people, the total daily ingesting dose is 0.04-0.05 L/d, LADD of DBPs via the respiratory route is 1.1 x 10(-7) - 6.8 x 10(-6) mg x (kg x d)(-1).

[Concentration limitations of pathogenic microorganisms in reclaimed water].

Using the technique of microbial risk assessment, concentration limitations of pathogenic microorganisms for various reclaimed water uses are studied. The concentration limitations are: Escherichia coli 70 MPN/L, Salmonella 0.5 CFU/L, Shigella 0.1 CFU/100L, Hepatitis A virus 0.001 PFU/100L, Rotavirus 1.2 x 10(-3) PFU/100L, Poliovirus 0.07 PFU/100L, Coxsackie 0.04 PFU/100L, Echovirus 0.05 PFU/100L, Cryptosporidium 0.1 oocysts/100 L, Giardia lamblia 0.03 cysts/100 L.