Neutrino mass and low-temperature calorimetry

We describe how the problem of measuring the neutrino mass led us to the development of low-temperature calorimetry. The search for a "17-keV neutrino" concluded with a negative result, but a wide range of applications are now carried on by us and by other groups in the fields of x-ray astronomy, recoil measurements of dark matter particles, high precision particle spectrometry, specific heat determinations, neutron detection, rare decay studies. The masses of the bolometers (calorimeters) extend from 1 mg to 1 Kg, nearly as large as for quantum detectors. By lowering the temperature into the 10-20 mK range, calorimetry is on the way to surpass substantially the high precision of particle metrology obtainable with the quantum detectors. Calorimeter developments and perspectives are discussed

New cell separation technique for the isolation and analysis of cells from biological mixtures in forensic caseworks

Aim To isolate mucosal cells of the perpetrator in a sexual assault case from a complex mixture of his mucosal cells and the victim’s skin by micromanipulation prior to genomic analysis. Methods To capture and analyze mucosal cells we used the micromanipulation with on-chip low volume polymerase chain reaction (LV-PCR). Consensus DNA profiles were generated from 5 replicate experiments. Results and conclusions We validated the use of micromanipulation with on-chip LV-PCR for genomic analysis of complex biological mixtures in a fatal rape case. The perpetrator’s mucosal cells were captured from nipple swabs of the victim, and a single-source DNA profile was generated from cell mixtures. These data suggest that micromanipulation with on-chip LV-PCR is an effective forensic tool for the analysis of specific cells from complex samples

Expression analysis of banana MaECHI1 during fruit ripening with different treatments

The main function of endochitinase is believed to be pathogenesis related protein. However, more and more scientists reported the roles of endochitinase in plant growth and development. In order to investigate the role of endochitinase in postharvest banana fruit ripening, an endochitinase gene known as MaECHI1 had been isolated from a suppression subtractive hybridization (SSH) complementary deoxyribonucleic acid (cDNA) library. MaECHI1 was mainly expressed in banana fruit and flowers. Ethylene biosynthesis, gene expression and chitinase activities in different stages of postharvest banana fruit with or without ethylene and 1-methylcycle–propene (1-MCP) treatments were investigated. The results show that under ethylene treatment, banana ethylene production, gene expression, and chitinase activities increased markedly at the onset of banana ripening. Moreover, banana ethylene production and MaECHI1 gene expression peaks appeared earlier with ethylene treatment than with other treatment. MaECHI1 gene expression was markedly responsive to the fruit ripening process and to exogenous ethylene treatment.Keywords: Banana (Musa acuminata L.AAA), endochitinase gene expression, ethylene production fruit ripenin

Integrated application of uniform design and least-squares support vector machines to transfection optimization

<p>Abstract</p> <p>Background</p> <p>Transfection in mammalian cells based on liposome presents great challenge for biological professionals. To protect themselves from exogenous insults, mammalian cells tend to manifest poor transfection efficiency. In order to gain high efficiency, we have to optimize several conditions of transfection, such as amount of liposome, amount of plasmid, and cell density at transfection. However, this process may be time-consuming and energy-consuming. Fortunately, several mathematical methods, developed in the past decades, may facilitate the resolution of this issue. This study investigates the possibility of optimizing transfection efficiency by using a method referred to as least-squares support vector machine, which requires only a few experiments and maintains fairly high accuracy.</p> <p>Results</p> <p>A protocol consists of 15 experiments was performed according to the principle of uniform design. In this protocol, amount of liposome, amount of plasmid, and the number of seeded cells 24 h before transfection were set as independent variables and transfection efficiency was set as dependent variable. A model was deduced from independent variables and their respective dependent variable. Another protocol made up by 10 experiments was performed to test the accuracy of the model. The model manifested a high accuracy. Compared to traditional method, the integrated application of uniform design and least-squares support vector machine greatly reduced the number of required experiments. What's more, higher transfection efficiency was achieved.</p> <p>Conclusion</p> <p>The integrated application of uniform design and least-squares support vector machine is a simple technique for obtaining high transfection efficiency. Using this novel method, the number of required experiments would be greatly cut down while higher efficiency would be gained. Least-squares support vector machine may be applicable to many other problems that need to be optimized.</p

Total Phenolic Contents and Antioxidant Capacities of Selected Chinese Medicinal Plants

Antioxidant capacities of 56 selected Chinese medicinal plants were evaluated using the Trolox equivalent antioxidant capacity (TEAC) and ferric reducing antioxidant power (FRAP) assays, and their total phenolic content was measured by the Folin-Ciocalteu method. The strong correlation between TEAC value and FRAP value suggested that the antioxidants in these plants possess free radical scavenging activity and oxidant reducing power, and the high positive correlation between antioxidant capacities and total phenolic content implied that phenolic compounds are a major contributor to the antioxidant activity of these plants. The results showed that Dioscorea bulbifera, Eriobotrya japonica, Tussilago farfara and Ephedra sinica could be potential rich sources of natural antioxidants

A Novel G Protein-Biased and Subtype-Selective Agonist for a G Protein-Coupled Receptor Discovered from Screening Herbal Extracts

Subtype selectivity and functional bias are vital in current drug discovery for G protein-coupled receptors (GPCRs) as selective and biased ligands are expected to yield drug leads with optimal on-target benefits and minimal side-effects. However, structure-based design and medicinal chemistry exploration remain challenging in part because of highly conserved binding pockets within subfamilies. Herein, we present an affinity mass spectrometry approach for screening herbal extracts to identify active ligands of a GPCR, the 5-HT2C receptor. Using this method, we discovered a naturally occurring aporphine 1857 that displayed strong selectivity for activating 5-HT2C without activating the 5-HT2A or 5-HT2B receptors. Remarkably, this novel ligand exhibited exclusive bias toward G protein signaling for which key residues were identified, and it showed comparable in vivo efficacy for food intake suppression and weight loss as the antiobesity drug, lorcaserin. Our study establishes an efficient approach to discovering novel GPCR ligands by exploring the largely untapped chemical space of natural products

High-throughput identification of G protein-coupled receptor modulators through affinity mass spectrometry screening

G protein-coupled receptors (GPCRs) represent the largest class of cell surface proteins and thus constitute an important family of therapeutic targets. Therefore, significant effort has been put towards the identification of novel ligands that can modulate the activity of a GPCR target with high efficacy and selectivity. However, due to limitations inherent to the most common techniques for GPCR ligand discovery, there is a pressing need for more efficient and effective ligand screening methods especially for the identification of potential allosteric modulators. Here we present a high-throughput, label-free and unbiased screening approach for the identification of small molecule ligands towards GPCR targets based on affinity mass spectrometry. This new approach features the usage of target-expressing cell membranes rather than purified proteins for ligand screening and allows the detection of both orthosteric and allosteric ligands targeting specific GPCRs. Screening a small compound library with this approach led to the rapid discovery of an antagonist for the 5-HT receptor and four positive allosteric modulators for GLP-1 receptor that were not previously reported. © 2018 The Royal Society of Chemistry

Characterization of DNA with an 8-oxoguanine modification

The oxidation of DNA resulting from reactive oxygen species generated during aerobic respiration is a major cause of genetic damage that, if not repaired, can lead to mutations and potentially an increase in the incidence of cancer and aging. A major oxidation product generated in cells is 8-oxoguanine (oxoG), which is removed from the nucleotide pool by the enzymatic hydrolysis of 8-oxo-2′-deoxyguanosine triphosphate and from genomic DNA by 8-oxoguanine-DNA glycosylase. Finding and repairing oxoG in the midst of a large excess of unmodified DNA requires a combination of rapid scanning of the DNA for the lesion followed by specific excision of the damaged base. The repair of oxoG involves flipping the lesion out of the DNA stack and into the active site of the 8-oxoguanine-DNA glycosylase. This would suggest that thermodynamic stability, in terms of the rate for local denaturation, could play a role in lesion recognition. While prior X-ray crystal and NMR structures show that DNA with oxoG lesions appears virtually identical to the corresponding unmodified duplex, thermodynamic studies indicate that oxoG has a destabilizing influence. Our studies show that oxoG destabilizes DNA (ΔΔG of 2–8 kcal mol−1 over a 16–116 mM NaCl range) due to a significant reduction in the enthalpy term. The presence of oxoG has a profound effect on the level and nature of DNA hydration indicating that the environment around an oxoG•C is fundamentally different than that found at G•C. The temperature-dependent imino proton NMR spectrum of oxoG modified DNA confirms the destabilization of the oxoG•C pairing and those base pairs that are 5′ of the lesion. The instability of the oxoG modification is attributed to changes in the hydrophilicity of the base and its impact on major groove cation binding