SSB functions as a sliding platform that migrates on DNA via reptation.

SSB proteins bind to and control the accessibility of single-stranded DNA (ssDNA), likely facilitated by their ability to diffuse on ssDNA. Using a hybrid single-molecule method combining fluorescence and force, we probed how proteins with large binding site sizes can migrate rapidly on DNA and how protein-protein interactions and tension may modulate the motion. We observed force-induced progressive unraveling of ssDNA from the SSB surface between 1 and 6 pN, followed by SSB dissociation at ∼10 pN, and obtained experimental evidence of a reptation mechanism for protein movement along DNA wherein a protein slides via DNA bulge formation and propagation. SSB diffusion persists even when bound with RecO and at forces under which the fully wrapped state is perturbed, suggesting that even in crowded cellular conditions SSB can act as a sliding platform to recruit and carry its interacting proteins for use in DNA replication, recombination and repair.

Restraint Stress, Foot Shock and Corticosterone Differentially Alter Autophagy in the Rat Hippocampus, Basolateral Amygdala and Prefrontal Cortex.

Autophagy is a conserved lysosomal degradation process that has recently been found to be associated with stress-related psychological diseases. However, previous studies have yielded inconsistent results regarding the effects of various stress patterns on autophagy in different brain regions. This discrepancy may arise from differences in autophagy flux across nuclei, the type of stress experienced, and the timing of autophagy assessment after stress exposure. In this study, we assessed autophagy flux in the rat hippocampus (HPC), medial prefrontal cortex (mPFC), and basal lateral amygdala (BLA) by quantifying protein levels of p-ULK1, LC3-I, LC3-II, and p62 via Western blot analysis at 15 min, 30 min, and 60 min following various stress paradigms: restraint stress, foot shock, single corticosterone injection, and chronic corticosterone treatment. We found that: (1) hippocampal autophagy decreased within 1 h of restraint stress, foot shock, and corticosterone injection, except for a transient increase at 30 min after restraint stress; (2) autophagy increased 1 h after restraint stress and corticosterone injection but decreased 1 h after foot shock in mPFC; (3) In BLA, autophagy increased 1 h after foot shock and corticosterone injection but decreased 1 h after restraint stress; (4) Chronic corticosterone increased autophagy in mPFC and BLA but had no effects in HPC. These findings suggest that stress regulates autophagy in a brain region- and stressor-specific manner within 1 h after stress exposure, which may contribute to the development of stress-related psychological disorders.

Construction of the first high-density SNP genetic map and identification of QTLs for the natural rubber content in Taraxacum kok-saghyz Rodin.

BACKGROUND: Taraxacum kok-saghyz Rodin (TKS) is a promising commercial alternative natural rubber (NR) yielding plant. Cultivating TKS with a high NR content is an important breeding target, and developing molecular markers related to NR content can effectively accelerate the breeding process of TKS. RESULTS: To construct a high-density SNP genetic map and uncover genomic regions related to the NR content in TKS, an F1 mapping population of TKS was constructed by crossing two parents (l66 and X51) with significant differences in NR contents. The NR content of the F1 plants ranged from 0.30 to 15.14% and was distributed normally with a coefficient of variation of 47.61%, indicating quantitative trait inheritance. Then, employing whole-genome resequencing (WGR), a TKS genetic linkage map of 12,680 bin markers comprising 322,439 SNPs was generated. Based on the genetic map and NR content of the F1 population, six quantitative trait loci (QTLs) for NR content with LOD > 4.0 were identified on LG01/Chr01 and LG06/Chr06. Of them, the 2.17 Mb genomic region between qHRC-C6-1 and qHRC-C6-2 on ChrA06, with 65.62% PVE in total, was the major QTL region. In addition, the six QTLs have significant additive genetic effects on NR content and could be used to develop markers for marker-assisted selection (MAS) in TKS with a high NR content. CONCLUSION: This work constructed the first high-density TKS genetic map and identified the QTLs and genomic regions controlling the NR content, which provides useful information for fine mapping, map-based cloning, and MAS in TKS.

Quantitative Detection of Natural Rubber Content in Eucommia ulmoides by Portable Pyrolysis-Membrane Inlet Mass Spectrometry.

Eucommia ulmoides gum (EUG) is a natural polymer predominantly consisting of trans-1,4-polyisoprene. Due to its excellent crystallization efficiency and rubber-plastic duality, EUG finds applications in various fields, including medical equipment, national defense, and civil industry. Here, we devised a portable pyrolysis-membrane inlet mass spectrometry (PY-MIMS) approach to rapidly, accurately, and quantitatively identify rubber content in Eucommia ulmoides (EU). EUG is first introduced into the pyrolyzer and pyrolyzed into tiny molecules, which are then dissolved and diffusively transported via the polydimethylsiloxane (PDMS) membrane before entering the quadrupole mass spectrometer for quantitative analysis. The results indicate that the limit of detection (LOD) for EUG is 1.36 µg/mg, and the recovery rate ranges from 95.04% to 104.96%. Compared to the result of pyrolysis-gas chromatography (PY-GC), the average relative error is 1.153%, and the detection time was reduced to less than 5 min, demonstrating that the procedure was reliable, accurate, and efficient. The method has the potential to be employed to precisely identify the rubber content of natural rubber-producing plants such as Eucommia ulmoides, Taraxacum kok-saghyz (TKS), Guayule, and Thorn lettuce.

The Application of Cinnamon Twig Extract as an Inhibitor of Listeriolysin O against Listeria monocytogenes Infection.

As a major virulence factor of Listeria monocytogenes (L. monocytogenes), listeriolysin O (LLO) can assist in the immune escape of L. monocytogenes, which is critical for the pathogen to evade host immune recognition, leading to various infectious diseases. Cinnamon twig (CT), as a traditional medicine, has been widely used in clinics for multiple functions and it has exhibited excellent safety, efficacy and stability. There are few reports on the effects of the extracts of traditional medicine on bacterial virulence factors. CT has not been reported to be effective in the treatment of L. monocytogenes infection. Therefore, this study aims to explore the preventive effect of CT against L. monocytogenes infection in vivo and in vitro by targeting LLO. Firstly, a hemolysis assay and a cell viability determination are used to detect the effect of CT extract on the inhibition of the cytolytic activity of LLO. The potential mechanism through which CT extract inhibits LLO activity is predicted through network pharmacology, molecular docking assay, real-time polymerase chain reaction (RT-PCR), Western blotting and circular dichroism (CD) analysis. The experimental therapeutic effect of CT extract is examined in a mouse model infected with L. monocytogenes. Then, the ingredients are identified through a high-performance liquid chromatography (HPLC) and thin layer chromatography (TLC) analysis. Here we find that CT extract, containing mainly cinnamic acid, cinnamaldehyde, ß-sitosterol, taxifolin, catechin and epicatechin, shows a potential inhibition of LLO-mediated hemolysis without any antimicrobial activity. The results of the mechanism research show that CT extract treatment can simultaneously inhibit LLO expression and oligomerization. Furthermore, the addition of CT extract led to a remarkable alleviation of LLO-induced cytotoxicity. After treatment with CT extract, the mortality, bacterial load, pathological damage and inflammatory responses of infected mice are significantly reduced when compared with the untreated group. This study suggests that CT extract can be a novel and multicomponent inhibitor of LLO with multiple strategies against L. monocytogenes infection, which could be further developed into a novel treatment for infections caused by L. monocytogenes.

Stable Long Cycling of Small Molecular Organic Acid Electrode Materials Enabled by Nonflammable Eutectic Electrolyte.

Small molecule organic acids as electrode materials possess the advantages of high theoretical capacity, low cost, and good processability. However, these electrode materials suffer from poor cycling stability due to the inevitable dissolution of organic molecules in the electrolytes. Here, a eutectic mixture of lithium bis(trifluoromethanesulfonyl)imide and N-methylamine is employed as a eutectic electrolyte in Li-ion batteries with small molecule organic acids as electrodes. To enhance the cycling stability of the electrolyte, fluoroethylene carbonate is used as an additive. The electrolyte exhibits nonflammability, high ionic conductivity, and good electrochemical stability. Molecular dynamics simulations and density functional theory are performed to further investigate the solvation chemistry of the eutectic electrolyte. The well-designed eutectic electrolyte inhibits the dissolution of terephthalic acid effectively and displays superior performance with a capacity retention of ≈84% after 2000 cycles at a high current density of 1 A g-1 . It also enables stable cycling of more than 900 cycles at a high current density of 2 A g-1 at 60 °C. This study provides a strategy to enhance the cycling stability and safety of Li-ion batteries with organic electrode materials.

Prenatal Morphine Exposure Differentially Alters Addictive and Emotional Behavior in Adolescent and Adult Rats in a Sex-Specific Manner.

The effects of prenatal opioid exposure in adult animals has been widely studied, but little is known about the effects of prenatal opioid on adolescents. Most of the risk behaviors associated with drug abuse are initiated during adolescence. The developmental state of the adolescent brain makes it vulnerable to initiate drug use and susceptible to drug-induced brain changes. In this study, pregnant rats were subcutaneously injected with an increasing dose of morphine (5 mg/kg, 7 mg/kg, 10 mg/kg) for 9 days since the gestation day 11. The effects of prenatal morphine (PNM) on learning and memory, anxiety- and depressive- like behavior, morphine induced conditioned place preference (CPP) as well as locomotor sensitization were tested in both adolescent and adult rats. The results showed that: (1) PNM decreased anxiety-like behavior in both adolescent and adult female rats, but not males; (2) PNM decreased depressive-like behavior in adolescent but increased depressive -like behavior in adult females; (3) PNM increased low dose morphine induced locomotor sensitization in females; (4) PNM decreased tyrosine hydroxylase (TH) expression in the prefrontal cortex but decreased dopamine D1 receptor expression in the nucleus-accumbens (NAc) in female rats. These results suggested that PNM altered the emotional and addictive behavior mainly in female rats, with female rats being less anxiety and depressive during adolescence, but more depressive in adult, and more sensitive to low dose morphine induced locomotor activity sensitization, which might be mediated in part by the differential expression of the TH, dopamine D1 receptors in the female brain.

One Step Closer to an Ideal Insensitive Energetic Molecule: 3,5-Diamino-6-hydroxy-2-oxide-4-nitropyrimidone and its Derivatives.

Reaching the goal of developing an insensitive high-energy molecule (IHEM) is a major challenge. In this study, 3,5-diamino-6-hydroxy-2-oxide-4-nitropyrimidone (IHEM-1) was synthesized in one step from 2,4,6-triamino-5-nitropyrimidine-1,3-dioxide hydrate (ICM-102 hydrate). The density of compound IHEM-1 is 1.95 g cm-3 with a decomposition temperature of 271 °C. Its detonation velocity and pressure are 8660 m s-1 and 33.64 GPa, respectively, which are far superior to the detonation performance of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), while its sensitivity is identical with that of TATB. In addition, four derivatives (1a, chloride; 1b, nitrate; 1c, perchlorate; and 1d, dinitramide) were prepared on the basis of the weak base site (N-O group) and show excellent energetic properties. By combining a series of advantages, including simple preparation, high yield, high density, very low solubility in aqueous solution, high thermostability, insensitivity, and excellent detonation performance, IHEM-1 approaches an ideal insensitive high-energy molecule. Compounds 1b-1d are also competitive as new high-energy-density materials.

Determinants of target prioritization and regulatory hierarchy for the bacterial small RNA SgrS.

Small RNA (sRNA) regulators promote efficient responses to stress, but the mechanisms for prioritizing target mRNA regulation remain poorly understood. This study examines mechanisms underlying hierarchical regulation by the sRNA SgrS, found in enteric bacteria and produced under conditions of metabolic stress. SgrS posttranscriptionally coordinates a nine-gene regulon to restore growth and homeostasis. An in vivo reporter system quantified SgrS-dependent regulation of target genes and established that SgrS exhibits a clear target preference. Regulation of some targets is efficient even at low SgrS levels, whereas higher SgrS concentrations are required to regulate other targets. In vivo and in vitro analyses revealed that RNA structure and the number and position of base pairing sites relative to the start of translation impact the efficiency of regulation of SgrS targets. The RNA chaperone Hfq uses distinct modes of binding to different SgrS mRNA targets, which differentially influences positive and negative regulation. The RNA degradosome plays a larger role in regulation of some SgrS targets compared to others. Collectively, our results suggest that sRNA selection of target mRNAs and regulatory hierarchy are influenced by several molecular features and that the combination of these features precisely tunes the efficiency of regulation of multi-target sRNA regulons.

Inactivation of endopeduncular nucleus impaired fear conditioning and hippocampal synaptic plasticity in rats.

The internal globus pallidus (GPi) is one part of basal ganglion nucleuses which play fundamental role in motor function. Recent studies indicated that GPi could modulate emotional processing and learning, but the possible mechanism remains still unknown. In this study, the effects of endopeduncular nucleus (EP, a rodent homolog of GPi) on fear conditioning were tested in rats. GABAA receptor agonist muscimol was bilaterally delivered into the EP 15 min before or immediately after fear conditioning in rats. We found that EP inactivation impaired the acquisition but not consolidation of fear memory in rats. Furthermore, the long-term potentiation (LTP) in hippocampal CA1 area was impaired, and the learning related phosphorylation of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor (AMPAR) subunit 1 (GluA1) at the Ser845 site in hippocampus was decreased in muscimol treated group. These results demonstrated that dysfunction of EP impaired hippocampal dependent learning and memory in rats.

Corticosterone Signaling and a Lateral Habenula-Ventral Tegmental Area Circuit Modulate Compulsive Self-Injurious Behavior in a Rat Model.

Self-injurious behavior (SIB) is commonly observed in patients with neuropsychiatric disorders, as well as in nonclinical populations with stress-related mental-health problems. However, the exact circuitry mechanisms underlying SIB have remained poorly understood. Here, with bilateral injection of muscimol into the entopeduncular nucleus (EP), we established a rat model of SIB. Following the muscimol injection, the male rats exhibited in a dose-dependent manner stereotypic self-biting behavior that lasted for hours and often resulted in wounds of various severities. The SIB was associated with an elevated level of serum corticosterone and could be exacerbated by enhancing the corticosterone signaling and, conversely, alleviated by inhibiting the corticosterone signaling. Activity mapping using c-fos immunostaining, combined with connectivity mapping using herpes simplex virus-based anterograde tracing from the EP and pseudorabies virus-based retrograde tracing from the masseter muscle, revealed the potential involvement of many brain areas in SIB. In particular, the lateral habenula (LHb) and the ventral tegmental area (VTA), the two connected brain areas involved in stress response and reward processing, showed a significant increase in neuronal activation during SIB. Furthermore, suppressing the LHb activity or modulating the GABAergic transmission in the VTA could significantly reduce the occurrence of SIB. These results demonstrate the importance of stress hormone signaling and the LHb-VTA circuit in modulating SIB resulting from EP malfunction, and suggest potential targets for therapeutic intervention of SIB and related disorders.SIGNIFICANCE STATEMENT Self-injurious behavior (SIB) occurs in ∼4% of the general population, with substantially higher occurrence among adolescents and patients of neuropsychiatric disorders. Stress has been linked to the occurrence of SIB, yet the underlying mechanisms have remained unclear. Using a rat model of SIB induced by disruption of activity in the entopeduncular nucleus (EP), we found that the behavior is regulated by stress and linked to corticosterone signaling. Viral tracing and c-fos immunostaining revealed the involvement of various subcortical areas, especially the EP-lateral habenula (LHb)-ventral tegmental area (VTA) circuit, in SIB. Furthermore, regulating activity in the LHb or the VTA alleviates SIB. These results may have implications in the development of new strategies for treating SIB.

Interactive effects of morphine and dopamine receptor agonists on spatial recognition memory in mice.

Both opiates and dopamine play important roles in learning and memory. Although synergistic action between these two neurotransmitters has been found, their functional roles remain unclear. Here, low dose morphine (2.5 mg/kg) and low dose dopamine receptor agonists (apomorphine 0.05 mg/kg; SKF38393 0.01 mg/kg; bromocriptine 0.05 mg/kg), which have no effects on spatial recognition memory, were injected intraperitoneally into mice 30 minutes before a memory test in a two-trial recognition Y-maze. The Y-maze is based on the innate tendency of rodents to explore novel environments and is therefore suitable for exploring the effects of morphine on learning and memory. Our results showed that both D1-like and D2-like dopamine receptor agonists dose-dependently impaired the retrieval of spatial recognition memory in the Y-maze, and co-administration of memory ineffective doses of apomorphine (0.05 mg/kg), SKF38393 (0.01 mg/kg), or bromocriptine (0.05 mg/kg) and of morphine (2.5 mg/kg) resulted in impaired spatial recognition memory retrieval in mice. These findings suggest the existence of interactions between morphine and dopamine receptor agonists in memory processing and that activation of the dopamine system might contribute to morphine-induced impairment of memory, which could provide insight into human addiction.

Advanced Parental Age Impaired Fear Conditioning and Hippocampal LTD in Adult Female Rat Offspring.

Advanced maternal or paternal age is associated with increased risks of cognitive and emotional disorders. Chronic stress is also a common experience in human life that causes psychiatric diseases. However, the synergistic effects of these two factors on offspring are rarely studied. In the present study, the offspring of both young (3-4 months) and old (12-14 months) rat parents were given CUMS for 21 days at the age of 4 weeks. The effects of advanced parental age and chronic unpredictable mild stress (CUMS) on emotional and cognitive behaviors and the related cellular mechanisms were investigated by using behavioral and electrophysiological techniques. We found that CUMS decreased sucrose consumption, increased anxiety, and impaired learning and memory in offspring from both old and young breeders. However, advanced parental age impaired fear memory and spatial memory mainly in female offspring. The serum corticosterone of female offspring was lower than males, but advanced parental age significantly elevated serum corticosterone in female offspring in response to electrical foot shocks. In addition, hippocampal LTD was severely impaired in female offspring from older parents. Our results indicated that female offspring from older breeders might be more sensitive to stress, and the hippocampal function was more vulnerable. These results might provide experimental basis for the prevention and treatment of advanced parental age related psychiatric disorders in future.

Synthesis of Denser Energetic Metal-Organic Frameworks via a Tandem Anion-Ligand Exchange Strategy.

High-density materials have attracted extensive attention because of their broad applications. However, strategies for improving the densities of MOFs and preparing denser MOFs remain almost unexplored. Herein, we propose a tandem anion-ligand exchange strategy for synthesizing denser MOFs by using three-dimensional cationic MOFs (3D CMOFs) with pillared layered structures as precursors and high-density anions and small monotopic ligands as exogenous guests. By means of this strategy, we choose the high-density nitroformate ion [C(NO2)3-] as an exogenous anion and water as an exogenous ligand to successfully synthesize two layered CMOFs. Single-crystal X-ray diffraction showed that after this transformation, the extra-framework anions are replaced with the C(NO2)3- anions, and the distances between adjacent layers in the two-dimensional (2D) networks are more than 3.70 Å shorter than those of their 3D precursors. The resultant materials exhibit higher densities, higher heats of detonation, higher nitrogen and oxygen contents, and lower metal contents. In particular, the density of {Cu(atrz)2[C(NO2)3]2(H2O)2·atrz·2H2O}n (2b, ρ = 1.76 g cm-3, atrz = 4,4'-azo-1,2,4-triazole) is increased by 0.12 g cm-3 compared to its 3D precursor {2a, [Cu(atrz)3(NO3)2·2H2O]n, ρ = 1.64 g cm-3}, and its heat of detonation is also enhanced to more than 1900 kJ kg-1. The resultant 2D layered CMOFs are also new potential high-energy density materials. This work may provide new insights into the design and synthesis of high-density MOFs. Moreover, we anticipate that the approach reported here would be useful for the preparation of new MOFs, in particular, which are otherwise difficult or unfeasible through traditional synthetic routes.

Micromorphological characterization and label-free quantitation of small rubber particle protein in natural rubber latex.

Commercial natural rubber is traditionally supplied by Hevea brasiliensis, but now there is a big energy problem because of the limited resource and increasing demand. Intensive study of key rubber-related substances is urgently needed for further research of in vitro biosynthesis of natural rubber. Natural rubber is biosynthesized on the surface of rubber particles. A membrane protein called small rubber particle protein (SRPP) is a key protein associated closely with rubber biosynthesis; however, SRPP in different plants has been only qualitatively studied, and there are no quantitative reports so far. In this work, H. brasiliensis was chosen as a model plant. The microscopic distribution of SRPP on the rubber particles during the washing process was investigated by transmission electron microscopy-immunogold labeling. A label-free surface plasmon resonance (SPR) immunosensor was developed to quantify SRPP in H. brasiliensis for the first time. The immunosensor was then used to rapidly detect and analyze SRPP in dandelions and prickly lettuce latex samples. The label-free SPR immunosensor can be a desirable tool for rapid quantitation of the membrane protein SRPP, with excellent assay efficiency, high sensitivity, and high specificity. The method lays the foundation for further study of the functional relationship between SRPP and natural rubber content.

Single molecule analysis of Thermus thermophilus SSB protein dynamics on single-stranded DNA.

Single-stranded (ss) DNA binding (SSB) proteins play central roles in DNA replication, recombination and repair in all organisms. We previously showed that Escherichia coli (Eco) SSB, a homotetrameric bacterial SSB, undergoes not only rapid ssDNA-binding mode transitions but also one-dimensional diffusion (or migration) while remaining bound to ssDNA. Whereas the majority of bacterial SSB family members function as homotetramers, dimeric SSB proteins were recently discovered in a distinct bacterial lineage of extremophiles, the Thermus-Deinococcus group. Here we show, using single-molecule fluorescence resonance energy transfer (FRET), that homodimeric bacterial SSB from Thermus thermophilus (Tth) is able to diffuse spontaneously along ssDNA over a wide range of salt concentrations (20-500 mM NaCl), and that TthSSB diffusion can help transiently melt the DNA hairpin structures. Furthermore, we show that two TthSSB molecules undergo transitions among different DNA-binding modes while remaining bound to ssDNA. Our results extend our previous observations on homotetrameric SSBs to homodimeric SSBs, indicating that the dynamic features may be shared among different types of SSB proteins. These dynamic features of SSBs may facilitate SSB redistribution and removal on/from ssDNA, and help recruit other SSB-interacting proteins onto ssDNA for subsequent DNA processing in DNA replication, recombination and repair.

Neuroprotection of Early Locomotor Exercise Poststroke: Evidence From Animal Studies.

Early locomotor exercise after stroke has attracted a great deal of attention in clinical and animal research in recent years. A series of animal studies showed that early locomotor exercise poststroke could protect against ischemic brain injury and improve functional outcomes through the promotion of angiogenesis, inhibition of acute inflammatory response and neuron apoptosis, and protection of the blood-brain barrier. However, to date, the clinical application of early locomotor exercise poststroke was limited because some clinicians have little confidence in its effectiveness. Here we review the current progress of early locomotor exercise poststroke in animal models. We hope that a comprehensive awareness of the early locomotor exercise poststroke may help to implement early locomotor exercise more appropriately in treatment for ischemic stroke.

A simple method for the prediction of the detonation performances of metal-containing explosives.

Accurate prediction to the detonation performances of different kinds of energetic materials has attracted significant attention in the area of high energy density materials (HEDMs). A common approach for the estimation of CHNO explosives is the Kamlet-Jacobs (K-J) equation. However, with the development of energetic materials, the components of explosives are no longer restricted to CHNO elements. In this study, we have extended the K-J equation to the calculation of certain metal-containing explosives. A new empirical method, in which metal elements are assumed to form metallic oxides, has been developed on the basis of the largest exothermic principle. In this method, metal oxides can be deemed as inert solids that release heat other than gases. To evaluate the prediction accuracy of new method, a commercial program EXPLO5 has been employed for the calculation. The difference involved in the ways of treating products has been taken into account, and the detonation parameters from two methods were subject to close comparison. The results suggest that the mean absolute values (MAVs) of relative deviation for detonation velocity (D) and detonation pressure (P) are less than 5%. Overall, this new method has exhibited excellent accuracy and simplicity, affording an efficient way to estimate the performance of explosives without relying on sophisticated computer programs. Therefore, it will be helpful in designing and synthesizing new metallic energetic compounds.

Arabidopsis AtPAP1 transcription factor induces anthocyanin production in transgenic Taraxacum brevicorniculatum.

KEY MESSAGE: This study developed a new purple coloured Taraxacum brevicorniculatum plant through genetic transformation using the Arabidopsis AtPAP1 gene, which overproduced anthocyanins in its vegetative tissues. Rubber-producing Taraxacum plants synthesise high-quality natural rubber (NR) in their roots and so are a promising alternative global source of this raw material. A major factor in its commercialization is the need for multipurpose exploitation of the whole plant. To add value to the aerial tissues, red/purple plants of the rubber-producing Taraxacum brevicorniculatum species were developed through heterologous expression of the production of anthocyanin pigment 1 (AtPAP1) transcription factor from Arabidopsis thaliana. The vegetative tissue of the transgenic plants showed an average of a 48-fold increase in total anthocyanin content over control levels, but with the exception of pigmentation, the transgenic plants were phenotypically comparable to controls and displayed similar growth vigor. Southern blot analysis confirmed that the AtPAP1 gene had been integrated into the genome of the high anthocyanin Taraxacum plants. The AtPAP1 expression levels were estimated by quantitative real-time PCR and were highly correlated with the levels of total anthocyanins in five independent transgenic lines. High levels of three cyanidin glycosides found in the purple plants were characterized by high performance liquid chromatography-mass spectrum analysis. The presence of NR was verified by NMR and infrared spectroscopy, and confirmed that NR biosynthesis had not been affected in the transgenic Taraxacum lines. In addition, other major phenylpropanoid products such as chlorogenic acid and quercetin glycosides were also enhanced in the transgenic Taraxacum. The red/purple transgenic Taraxacum lines described in this study would increase the future application of the species as a rubber-producing crop due to its additional health benefits.

Extraction process and characterization of Taraxacum kok-saghyz (TKS) latex.

Taraxacum kok-saghyz (TKS) latex is a natural latex produced from its root, and its extraction optimization process is mainly studied in the present paper. The composition of fresh roots of TKS was quantitatively analyzed, and the results showed that the moisture content of the fresh root was approximately 70 %, and the rubber content averaged to 6 % (dry weight ratio). An optimal process route for extracting the TKS latex was finally determined, making the extraction efficiency reach about 80 %, and a new latex extraction process was established and optimized and named "the process of Buffer Extraction TKS Latex (BETL)". Hevea latex, extracted TKS latex and TKS latex collected directly from the broken roots were compared for study. The results showed that, like Hevea latex, the appearance of TKS latex was milky white; and after centrifugation, both showed four layers from top to bottom: rubber particles, Frey-Wyssling particles, C-serum and lutoids. The results of the composition analysis showed that the concentration of TKS latex ranged from 54.54 % to 68.25 %, which is close to that of concentrated Hevea latex; the moisture content of TKS latex was between 31.75 % and 45.46 %. The protein content of TKS latex was 13.51 mg/mL, which was lower than that of Hevea latex at the same rubber hydrocarbon concentration. The molecular structures and properties of Hevea latex, the extracted TKS latex, and the collected TKS latex were characterized by FTIR, 13C NMR, GPC, TG, SEM and LPSA, and the results showed that the main components and structure of the three latexes were similar, which are all cis-1,4-polyisoprene, and include the proteins and lipids. The distributions molecular weights of the three latexes all showed a bimodal distribution, but the molecular weight of the latex collected from TKS was lower, which indicates the larger molecules were difficult to flow outside the root automatically. The Hevea latex and TKS latex rubber particles were both core-shell structure and the size distribution were bimodal, which was consistent with the GPC analysis results.