Novel Small Molecule Matrix Screening for Simultaneous MALDI Mass Spectrometry Imaging of Multiple Lipids and Phytohormones

Most of the traditional matrices cannot simultaneously image multiple lipids and phytohormones, so screening and discovery of novel matrices stand as essential approaches for broadening the application scope of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). In this work, 12 organic small molecule compounds were comprehensively screened and investigated as potential MALDI matrices for simultaneous imaging analysis of various lipids and phytohormones. In the positive ionization mode, p-nitroaniline, m-nitroaniline, and 2-aminoterephthalic acid displayed good performance for the highly sensitive detection of lysophosphatidylcholines (LPCs), phosphatidylcholines (PCs), and triacylglycerols (TGs). Furthermore, p-nitroaniline possessed excellent characteristics of strong ultraviolet absorption and homogeneous cocrystallization, making it a desirable matrix for MALDI-MSI analysis of eight plant hormones. Compared with conventional matrices (2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinnamic acid (CHCA), and 9-aminoacridine (9-AA), the use of p-nitroaniline resulted in higher ionization efficiency, superior sensitivity, and clearer imaging images in dual polarity mode. Our research offers valuable guidance and new ideas for future endeavors in matrix screening

Tracking Spatial Distribution Alterations of Multiple Endogenous Molecules during Lentil Germination by MALDI Mass Spectrometry Imaging

Exploring the spatial distribution alterations of metabolites during lentil germination is essential to reveal the nutritional value, physiological function, and metabolic pathway in lentils. Hence, an effective matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) method was established for the first time to visualize the spatial localization changes of 53 metabolites in lentils during germination for 12–72 h. The results of MALDI-MSI analysis showed that phosphatidylinositols, phosphatidylethanolamines, phosphatidylglycerols, and phosphatidic acids were mainly located in the cotyledons of lentils throughout the germination process, while triacylglycerols, phosphatidylcholines, diacylglycerols, amino acids, choline, and spermine spread throughout the lentil tissue at the initial stage of germination and gradually presented obvious distribution characteristics in the radicle with increasing germination time. Heat map analysis was used to visualize the correlations between lipid content changes and germination time, which supported the use of germinated lentils as nutraceutical or functional food

miR-132/182 regulating BDNF expression.

<p>(<b>A, B</b>) Detection of BDNF by western blotting. SH-SY5Y cells were treated with miR-182 or miR-132, the results showed that BDNF expression in the miR-182- or miR-132-treated cultures was much lower than that of negative control miRNA cultures. *<i>P</i><0.05, miR-182- or miR-132-treated cultures <i>vs.</i> control cultures. Relative values for BDNF <i>vs</i>. Actin are indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0063648#pone-0063648-g002" target="_blank">Fig.2B</a>.</p

Relationship between levels of serum BDNF and its related miRNAs.

<p>(<b>A</b>) A significant negative correlation (Spearman <i>r_s</i> = −0.307, <i>P = </i>0.006) between the serum BDNF and miR-132 levels in depressed patients (n = 40) and controls (n = 40). (<b>B</b>) No significant correlation (Spearman <i>r_s</i> = 0.098, <i>P = </i>0.385) was found between the serum BDNF and miR-182 levels in depressed patients (n = 40) and controls (n = 40).</p

The sequences of chemically synthesized miRNA^a.

a<p>The selected miRNAs were chemically synthesized in the form of small interfering RNA (siRNA) duplexes.</p

BDNF serum levels and its related miRNAs.

<p>(<b>A</b>) BDNF concentrations in patients and controls. The serum levels of BDNF in the patients with depression (n = 40; 20.05±5.98 ng/ml) were significantly decreased compared with those of the healthy controls (n = 40; 25.22±5.17 ng/ml). (<b>B</b>) The targeting site on BDNF-mRNA-3′UTR by miR-182, which was aligned with the mRNA-3′UTR of human <i>bdnf</i> gene with the nucleotide position. Vertical lines indicate identity.</p

Weekly distribution of AFP cases <15 years of age by classification in 2011 and 2012 in Ngawa Tibetan and Qiang Autonomous Prefecture, Sichuan Province, China.

<p>Note: VDPV, vaccine-derived poliovirus; AFP, acute flaccid paralysis.</p

Rounds, dates, target population, and numbers of persons immunized for SIAs by province, 2012.

<p>Rounds, dates, target population, and numbers of persons immunized for SIAs by province, 2012.</p

Antibody seropositivity of type I, type Π, and type by age group in Ngawa County, Ngawa Tibetan and Qiang Autonomous Prefecture, Sichuan Province, China, 2012.

<p>Antibody seropositivity of type I, type Π, and type by age group in Ngawa County, Ngawa Tibetan and Qiang Autonomous Prefecture, Sichuan Province, China, 2012.</p

Descriptive characteristics of case patients and close contacts in an outbreak of type Π cVDPVs in Ngawa County, Ngawa Tibetan and Qiang Autonomous Prefecture, Sichuan Province, China, August 2011–February 2012.

<p>Descriptive characteristics of case patients and close contacts in an outbreak of type Π cVDPVs in Ngawa County, Ngawa Tibetan and Qiang Autonomous Prefecture, Sichuan Province, China, August 2011–February 2012.</p