Mass spectrometry-based lipidomics to explore the biochemical effects of naphthalene toxicity or tolerance in a mouse model.

Naphthalene causes mouse airway epithelial injury. However, repeated exposures of naphthalene result in mouse airway tolerance. Previous results showed that toxicity or tolerance was correlated with changes of phosphorylcholine-containing lipids. In this study, a mass spectrometry-based lipidomic approach was applied to examine the effects of naphthalene-induced injury or tolerance in the male ICR mice. The injury model was vehicle x 7 plus 300 mg/kg naphthalene while the tolerant one was 200 mg/kg daily x 7 followed by 300 mg/kg naphthalene on day 8. The lung, liver, kidney, and serum samples were collected for profiles of phosphorylcholine-containing lipids including phosphatidylcholines (PCs) and sphingomyelins (SMs). A partial least-square-discriminate analysis model showed different lung phosphorylcholine-containing lipid profiles from the injured, tolerant, and control groups. Perturbation of diacyl-PCs and plasmenylcholines may be associated with enhanced membrane flexibility and anti-oxidative mechanisms in the lungs of tolerant mice. Additionally, alterations of lyso-PCs and SMs may be responsible for pulmonary dysfunction and inflammation in the lungs of injured mice. Moreover, serum PC(16:0/18:1) has potential to reflect naphthalene-induced airway injuries. Few phosphorylcholine-containing lipid alterations were found in the mouse livers and kidneys across different treatments. This study revealed the changes in lipid profiles associated with the perturbations caused by naphthalene tolerance and toxicity; examination of lipids in serum may assist biomarker development with the potential for application in the human population.

Membrane lipid profiles of coral responded to zinc oxide nanoparticle-induced perturbations on the cellular membrane.

Zinc oxide nanoparticles (nZnOs) released from popular sunscreens used during marine recreation apparently endanger corals; however, the known biological effects are very limited. Membrane lipids constitute the basic structural element to create cell a dynamic structure according to the circumstance. Nano-specific effects have been shown to mechanically perturb the physical state of the lipid membrane, and the cells accommodating the actions of nZnOs can be involved in the alteration of the membrane lipid composition. To gain insight into the effects of nanoparticles on coral, glycerophosphocholine (GPC) profiling of the coral Seriatopora caliendrum exposed to nZnOs was performed in this study. Increasing lyso-GPCs, docosapentaenoic acid-possessing GPCs and docosahexaenoic acid-possessing GPCs and decreasing arachidonic acid-possessing GPCs were the predominant changes responded to nZnO exposure in the coral. A backfilling of polyunsaturated plasmanylcholines was observed in the coral exposed to nZnO levels over a threshold. These changes can be logically interpreted as an accommodation to nZnOs-induced mechanical disturbances in the cellular membrane based on the biophysical properties of the lipids. Moreover, the coral demonstrated a difference in the changes in lipid profiles between intra-colonial functionally differentiated polyps, indicating an initial membrane composition-dependent response. Based on the physicochemical properties and physiological functions of these changed lipids, some chronic biological effects can be incubated once the coral receives long-term exposure to nZnOs.

Intra-Colonial Functional Differentiation-Related Modulation of the Cellular Membrane in a Pocilloporid Coral Seriatopora caliendrum.

Scleractinian corals have displayed phenotypic gradients of polyps within a single genotypic colony, and this has profound implications for their biology. The intrinsic polymorphism of membrane lipids and the molecular interactions involved allow cells to dynamically organize their membranes to have physicochemical properties appropriate for their physiological requirements. To gain insight into the accommodation of the cellular membrane during ontogenetic shifts, intra-colony differences in the glycerophosphocholine profiling of a pocilloporid coral, Seriatopora caliendrum, were characterized using a previously validated method. Specifically, several major polyunsaturated phosphatidylcholines showed higher levels in the distal tissue of coral branches. In contrast, the corresponding molecules with 1-2-degree less unsaturation and plasmanylcholines were expressed more highly in the proximal tissue. The lipid profiles of these two colonial positions also contrasted sharply with regard to the saturated, monounsaturated, and lyso-glycerophosphocholine ratios. Based on the biochemical and biophysical properties of these lipids, the associated modulation of cellular membrane properties could be related to the physiological requirements, including coral growth and aging, of the functionally differentiated polyps. In this study, the metabolic regulation of membrane lipids involved in the functional differentiation of polyps within a S. caliendrum colony was identified.

Glycerophosphocholine molecular species profiling in the biological tissue using UPLC/MS/MS.

A strategy consisting of a two-phase analytical procedure was used to obtain detailed molecular species composition for glycerophosphocholines (GPCs) profiling in biological tissue using ultra performance liquid chromatography coupled with a triple quadrupole mass spectrometer operating under electrospray mode. In phase one of the analytical procedure, the precursor ion scan was first conducted to obtain the preliminary lipid profile that revealed the composition of the molecular species possessing phosphocholine structure in the biological tissue. In phase two of the analytical procedure, each product ion spectrum obtained for the GPC components in the profile was sequentially acquired for the determination of the molecular structure. A simple guide with high differentiability was proposed for the diacyl-, alkyl-acyl- and alk-1-enyl-acyl-GPC, and related lyso-GPCs molecular structure decision. Total 93 GPCs molecular species were identified in the fetal mouse lung with the relative amounts from 14.39% to less than 0.01% (normalizing by the total GPCs signal). The optimized chromatographic conditions were also proposed in the analytical procedure based on the compromise between the separation efficiency and electrospray signal response. The plate number of the probing GPCs was obviously improved to above 30,000 and the detection limits of the probing GPCs were between 0.002 and 0.016 ng/µL. The practical usability of the analytical procedure has been validated using a study of chemically induced early lung maturation. The metabolic difference between chemically treated and untreated fetal mouse lung was clearly distinguished by the composition of GPCs with several characteristics of molecular structure. The overall results showed that this two-phase analytical procedure was reliable for comprehensive GPC profiling.