A nanopore-based cucumber genome assembly reveals structural variations at two QTLs controlling hypocotyl elongation.

The Xishuangbanna (XIS) cucumber (Cucumis sativus var. xishuangbannanesis) is a semiwild variety that has many distinct agronomic traits. Here, long reads generated by Nanopore sequencing technology helped assembling a high-quality genome (contig N50 = 8.7 Mb) of landrace XIS49. A total of 10,036 structural/sequence variations (SVs) were identified when comparing with Chinese Long (CL), and known SVs controlling spines, tubercles, and carpel number were confirmed in XIS49 genome. Two QTLs of hypocotyl elongation under low light, SH3.1 and SH6.1, were fine-mapped using introgression lines (donor parent, XIS49; recurrent parent, CL). SH3.1 encodes a red-light receptor Phytochrome B (PhyB, CsaV3_3G015190). A ∼4 kb region with large deletion and highly divergent regions (HDRs) were identified in the promoter of the PhyB gene in XIS49. Loss of function of this PhyB caused a super-long hypocotyl phenotype. SH6.1 encodes a CCCH-type zinc finger protein FRIGIDA-ESSENTIAL LIKE (FEL, CsaV3_6G050300). FEL negatively regulated hypocotyl elongation but it was transcriptionally suppressed by long terminal repeats retrotransposon insertion in CL cucumber. Mechanistically, FEL physically binds to the promoter of CONSTITUTIVE PHOTOMORPHOGENIC 1a (COP1a), regulating the expression of COP1a and the downstream hypocotyl elongation. These above results demonstrate the genetic mechanism of cucumber hypocotyl elongation under low light.

Integrating molecular imprinting into flexible covalent organic frameworks for selective recognition and efficient extraction of aflatoxins.

Covalent organic frameworks (COFs) are promising adsorbents for extraction, but their selectivity for molecular recognition remains a challenging issue due to the very limited structural design with rigid structure. Herein, we report an elegant strategy for the design and synthesis of molecularly imprinted flexible COFs (MI-FCOFs) via one-pot reaction between the flexible building block of 2,4,6-tris(4-formylphenoxy)- 1,3,5-triazine and linear 4-phenylenediamine for selective extraction of aflatoxins. The flexible chain structure enabled the developed MI-FCOF to adjust the shape and conformation of frameworks to suit the template molecule, giving high selectivity for aflatoxins recognition. Moreover, MI-FCOF with abundant imprinted sites and function groups exhibited an exceptional adsorption capacity of 258.4 mg g-1 for dummy template which is 3 times that of no-imprinted FCOF (NI-FCOF). Coupling MI-FCOF based solid-phase extraction with high-performance liquid chromatography gave low detection limits of 0.003-0.09 ng mL-1 and good precision with relative standard deviations ≤ 6.7% for the determination of aflatoxins. Recoveries for the spiked rice, corn, wheat and peanut samples were in the range of 85.4%- 105.4%. The high selectivity of the developed MI-FCOF allows matrix-free determination of AFTs in food samples. This work offers a new way to the design of MI-FCOF for selective molecular recognition.

Surface imprinted-covalent organic frameworks for efficient solid-phase extraction of fluoroquinolones in food samples.

Molecularly imprinting on covalent organic frameworks (MI-COF) is a promising way to prepare selective adsorbents for effective extraction of fluoroquinolones (FQs). However, the unstable framework structure and complex imprinting process are challenging for the construction of MI-COF. Here, we report a facile surface imprinting approach with dopamine to generate imprinted cavities on the surface of irreversible COF for highly efficient extraction of FQs in food samples. The irreversible-linked COF was fabricated from hexahydroxytriphenylene and tetrafluorophthalonitrile to ensure COF stability. Moreover, the introduction of dopamine surface imprinted polymer into COF provides abundant imprinted sites and endows excellent selectivity for FQs recognition against other antibiotics. Taking enrofloxacin as a template molecule, the prepared MI-COF gave an exceptional adsorption capacity of 581 mg g-1, a 2.2-fold enhancement of adsorption capacity compared with nonimprinted COF. The MI-COF was further explored as adsorbent to develop a novel solid-phase extraction method coupled with high-performance liquid chromatography for the simultaneous determination of enrofloxacin, norfloxacin and ciprofloxacin. The developed method gave the low limits of detection at 0.003-0.05 ng mL-1, high precision with relative standard deviations less than 3.5%. The recoveries of spiked FQs in food samples ranged from 80.4% to 110.7%.

Lead exposure disturbs ATP7B-mediated copper export from brain barrier cells by inhibiting XIAP-regulated COMMD1 protein degradation.

The brain barrier is an important structure for metal ion homeostasis. According to studies, lead (Pb) exposure disrupts the transportation of copper (Cu) through the brain barrier, which may cause impairment of the nervous system; however, the specific mechanism is unknown. The previous studies suggested the X-linked inhibitor of apoptosis (XIAP) is a sensor for cellular Cu level which mediate the degradation of the MURR1 domain-containing 1 (COMMD1) protein. XIAP/COMMD1 axis was thought to be an important regulator in Cu metabolism maintenance. In this study, the role of XIAP-regulated COMMD1 protein degradation in Pb-induced Cu disorders in brain barrier cells was investigated. Pb exposure significantly increased Cu levels in both cell types, according to atomic absorption technology testing. Western blotting and reverse transcription PCR (RT-PCR) showed that COMMD1 protein levels were significantly increased, whereas XIAP, ATP7A, and ATP7B protein levels were significantly decreased. However, there were no significant effects at the messenger RNA (mRNA) level (XIAP, ATP7A, and ATP7B). Pb-induced Cu accumulation and ATP7B expression were reduced when COMMD1 was knocked down by transient small interfering RNA (siRNA) transfection. In addition, transient plasmid transfection of XIAP before Pb exposure reduced Pb-induced Cu accumulation, increased COMMD1 protein levels, and decreased ATP7B levels. In conclusion, Pb exposure can reduce XIAP protein expression, increase COMMD1 protein levels, and specifically decrease ATP7B protein levels, resulting in Cu accumulation in brain barrier cells.

The dissection of R genes and locus Pc5.1 in Phytophthora capsici infection provides a novel view of disease resistance in peppers.

BACKGROUND: Phytophthora capsici root rot (PRR) is a disastrous disease in peppers (Capsicum spp.) caused by soilborne oomycete with typical symptoms of necrosis and constriction at the basal stem and consequent plant wilting. Most studies on the QTL mapping of P. capsici resistance suggested a consensus broad-spectrum QTL on chromosome 5 named Pc.5.1 regardless of P. capsici isolates and resistant resources. In addition, all these reports proposed NBS-ARC domain genes as candidate genes controlling resistance. RESULTS: We screened out 10 PRR-resistant resources from 160 Capsicum germplasm and inspected the response of locus Pc.5.1 and NBS-ARC genes during P. capsici infection by comparing the root transcriptomes of resistant pepper 305R and susceptible pepper 372S. To dissect the structure of Pc.5.1, we anchored genetic markers onto pepper genomic sequence and made an extended Pc5.1 (Ext-Pc5.1) located at 8.35 Mb-38.13 Mb on chromosome 5 which covered all Pc5.1 reported in publications. A total of 571 NBS-ARC genes were mined from the genome of pepper CM334 and 34 genes were significantly affected by P. capsici infection in either 305R or 372S. Only 5 inducible NBS-ARC genes had LRR domains and none of them was positioned at Ext-Pc5.1. Ext-Pc5.1 did show strong response to P. capsici infection and there were a total of 44 differentially expressed genes (DEGs), but no candidate genes proposed by previous publications was included. Snakin-1 (SN1), a well-known antimicrobial peptide gene located at Pc5.1, was significantly decreased in 372S but not in 305R. Moreover, there was an impressive upregulation of sugar pathway genes in 305R, which was confirmed by metabolite analysis of roots. The biological processes of histone methylation, histone phosphorylation, DNA methylation, and nucleosome assembly were strongly activated in 305R but not in 372S, indicating an epigenetic-related defense mechanism. CONCLUSIONS: Those NBS-ARC genes that were suggested to contribute to Pc5.1 in previous publications did not show any significant response in P. capsici infection and there were no significant differences of these genes in transcription levels between 305R and 372S. Other pathogen defense-related genes like SN1 might account for Pc5.1. Our study also proposed the important role of sugar and epigenetic regulation in the defense against P. capsici.

[Effects of beta glucan in highland barley on blood glucose and serum lipid in high fat-induced C57 mouse].

OBJECTIVE: Study the effects of ß-glucan in highland barley on blood glucose and serum lipid in high fat diet induced C57 mouse. METHODS: Using table of random number, 40 male C57BL/6 mice were randomly divided into 4 groups (10 mice in each group) by weight: high dosage group (4% ß-glucan and high fat diet), low dosage group (2% ß-glucan and high fat diet), high fat diet group and normal control group. Food-intake and body weight of C57 mouse were observed. Glucose tolerance tests and examinations of fasting blood glucose were performed at the end of 11 weeks of intervention. Mice were sacrificed after 12 wk of treatment, and serum specimens were obtained to test relevant biochemical indicators. RESULTS: After 12 weeks raise, among high dosage group, low dosage group, high fat diet group and normal control group, the weight was (32.8 ± 1.5), (40.4 ± 1.9), (40.7 ± 2.1) and (33.5 ± 1.3) g, respectively (F = 55.26, P < 0.05); average food intake was (3.48 ± 0.56), (3.69 ± 0.76), (3.66 ± 0.81) and (3.54 ± 0.61) g/d respectively (F = 0.26, P > 0.05); fasting blood-glucose was (5.29 ± 1.59), (6.13 ± 1.75), (7.63 ± 1.09) and (4.24 ± 0.98) mmol/L respectively (F = 9.54, P < 0.01); serum insulin level was (1.97 ± 0.10), (2.44 ± 0.24), (3.02 ± 0.36) and (1.48 ± 0.28) ng/ml respectively (F = 47.58, P < 0.01); the area under blood glucose concentration curve was (25.81 ± 1.44), (30.42 ± 2.01), (35.17 ± 1.20) and (21.03 ± 1.24) mmol×L(-1)×h(-1), respectively (F = 64.98, P < 0.05); insulin resistance index was (9.84 ± 3.78), (13.69 ± 4.48), (21.54 ± 3.27) and (5.81 ± 1.59) respectively (F = 30.18, P < 0.01); serum total cholesterol (TC) level was (4.05 ± 0.88), (4.30 ± 0.48), (4.73 ± 0.66) and (3.37 ± 0.40) mmol/L respectively (F = 6.70, P < 0.01); serum triglyceride (TG) level was (0.90 ± 0.09), (0.98 ± 0.09), (1.05 ± 0.06) and (0.76 ± 0.26) mmol/L respectively (F = 6.75, P < 0.01); serum high-density lipoprotein cholesterol (HDL-C) level was (2.91 ± 0.59), (3.34 ± 0.46), (4.89 ± 0.42) and (3.24 ± 0.37) mmol/L respectively (F = 31.73, P < 0.01); serum low-density lipoprotein cholesterol (LDL-C) level was (0.25 ± 0.15), (0.42 ± 0.19), (0.72 ± 0.12) and (0.32 ± 0.11) mmol/L, respectively (F = 17.27, P < 0.01); free fatty acids (FFA) level was (1.06 ± 0.03), (1.05 ± 0.05), (1.18 ± 0.32) and (1.04 ± 0.02) mmol/L, respectively (F = 1.36, P > 0.05); HDL-C/LDL-C was (13.77 ± 5.51), (9.11 ± 3.53), (7.04 ± 1.65) and (11.21 ± 3.31), respectively (F = 5.24, P < 0.01). CONCLUSION: The ß-glucan in highland barley reduced the serum glucose and serum lipid, as well as insulin resistance and the risk of arterial sclerosis in high-fat induced C57 mouse.

Non-isothermal thermal decomposition reaction kinetics of 2-nitroimino-5-nitro-hexahydro-1,3,5-triazine (NNHT).

The thermal behavior and decomposition reaction kinetics of 2-nitroimino-5-nitro-hexahydro-1,3,5-triazine (NNHT) were investigated by TG-DTG and DSC under atmospheric pressure and flowing nitrogen gas conditions. The results show that the thermal decomposition process of NNHT has two mass loss stages. The exothermic decomposition reaction mechanism obeys chemical reaction rule. The kinetic parameters of the reaction are E(a)=131.77 kJ mol(-1), lg(A/s(-1))=12.56, respectively. The kinetic equation can be expressed as: dalpha/dt = 10(12.86)(1-alpha)(3/2)3(-1.5849 x 10(4)/T)). The critical temperature of thermal explosion of NNHT obtained from the peak temperature (T(p)) is T(bp)=467.22K. The entropy of activation (DeltaS( not equal)), enthalpy of activation (DeltaH( not equal)), and free energy of activation (DeltaG( not equal)) of the reaction are -7.978 J mol(-1)K(-1), 127.99 kJ mol(-1) and 131.62 kJ mol(-1), respectively.

[Simultaneous determination of trace amounts of iron(II), copper(I) and cobalt(II) in aloe by second derivative peak area spectrophotometry].

A new method for simultaneous determination of iron(II), copper(I) and cobalt(II) was established by second derivative peak area spectrophotometry in chromogenic system of 1,10-phenanthroline. The method could avoid disturbing by some ions. The accuracy and sensitivity were improved. There is a linear relationship in the range of 0.0-8.5 microg x mL(-1) for Fe(II); of 0.0-7.3 microg x mL(-1) for Cu(I); and of 0.0-5.9 microg x mL(-1) for Co(II). The method has been applied to simultaneous determination of iron(II), copper(I) and cobalt(II) in aloe with satisfactory results. The average recovery is 98.6%-102% and the RSD is 0.1%-0.2%. There is no remarkable difference between these results and those of ICP-AES method.