Influence of spermatozoal lipidomic profile on the cryoresistance of frozen spermatozoa from stallions.

The membrane of spermatozoa, which contributes to cellular cryoresistance, contains numerous lipids with a composition that directly affects membrane fluidity and the fertilization process. In light of variations in the degree of sensitivity in equine seminal freezing, this study aimed to correlate equine semen lipids with post-thawing characteristics of spermatozoa. We used ejaculates from 34 stallions, which were evaluated (total motility ≥ 60%), frozen and thawed and reevaluated for motility of spermatozoa, membrane integrity and lipid peroxidation. Lipid extraction of the fresh semen samples was performed by liquid-liquid extraction, and fingerprinting lipid analysis was conducted by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Based on the characteristics of spermatozoa after thawing, the animals could be separated into two groups: resistant (Good Freezers, n = 5) and sensitive (Bad Freezers, n = 6) to freezing, and their MALDI-MS data were then compared. The Good Freezers group showed a higher abundance of phosphatidylcholines (m/z 796.6, 846.6, 810.6, 854.6 and 732.6). The ions of m/z 812.6, 832.6, 836.6 and 838.6 belonging to the phosphatidylcholine lipid class were also positively correlated with motility of spermatozoa, whereas that of m/z 794.6 was negatively correlated with lipid peroxidation in thawed semen. The Bad Freezer group, displayed higher abundance of one phosphatidylcholines (m/z 806.6), as well as a sphingomyelins (m/z 703.5), which were negatively correlated (univariate analysis) with kinetics of spermatozoa after thawing (m/z 703.5) and with membrane integrity (m/z 792.6). The ion of m/z 717.5, assigned to phosphatidic acid, was negatively correlated with lipid peroxidation. In general therefore, the phosphatidylcholines are associated with higher quality of spermatozoa after thawing, especially in functional capacity, and that lipid semen composition was found to influence the resistance of spermatozoa to cryopreservation and may interfere with motility, membrane integrity and lipid peroxidation in stallions.

MALDI MS imaging investigation of the host response to visceral leishmaniasis.

Mass spectrometry imaging (MSI) of animal tissues has become an important tool for in situ molecular analyses and biomarker studies in several clinical areas, but there are few applications in parasitological studies. Leishmaniasis is a neglected tropical disease, and experimental mouse models have been essential to evaluate pathological and immunological processes and to develop diagnostic methods. Herein we have employed MALDI MSI to examine peptides and low molecular weight proteins (2 to 20 kDa) differentially expressed in the liver during visceral leishmaniasis in mice models. We analyzed liver sections of Balb/c mice infected with Leishmania infantum using the SCiLS Lab software for statistical analysis, which facilitated data interpretation and thus highlighted several key proteins and/or peptides. We proposed a decision tree classification for visceral leishmaniasis with distinct phases of the disease, which are named here as healthy, acute infection and chronic infection. Among others, the ion of m/z 4963 was the most important to identify acute infection and was tentatively identified as Thymosin ß4. This peptide was previously established as a recovery factor in the human liver and might participate in the response of mice to Leishmania infection. This preliminary investigation shows the potential of MALDI MSI to complement classical compound selective imaging techniques and to explore new features not yet recognized by these approaches.

Lipid profiles of follicular fluid from cows submitted to ovarian superstimulation.

Ovarian superstimulation with exogenous gonadotropins has been extensively used to produce in vivo-derived embryos for embryo transfer in cattle. This process modifies the antral follicle microenvironment and affects oocyte and embryo quality as well the differentiation of granulosa cells. Lipids play significant roles in the cell, such as energy storage, cell structure, and fine-tuning of the physical properties and functions of biological membranes. The phospholipid (PL) contents as well as the effects of superstimulatory treatments on the PL profile of follicular fluid from cows, however, remain unknown. Therefore, to gain insight into the effects of superstimulation with follicle-stimulating hormone (FSH; P-36 protocol) or FSH combined with equine chorionic gonadotropin (eCG; P-36/eCG protocol) on the profile and abundance of PL from cows submitted or not submitted to superstimulatory protocols, were treated with these two superstimulatory protocols. As a control, non-superstimulated cows were only submitted to estrous synchronization. The follicular fluid was aspirated, the remaining cells removed and the follicular fluid stored at -80 °C until extraction. The lipid screening was performed by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and this technique allowed the identification of sphingomyelins (SM) and phosphatidylcholines (PC) and phosphoethanolamines (PE). The relative abundance of the ions observed in the three experimental groups was analyzed by multivariate and univariate statistical models. The phospholipid SM (16:0) and PC (36:4) and/or PC (34:1) were less (P < 0.05) abundant in the P-36 group compared to the control or P-36/eCG groups. However, the PC (34:2) was more (P < 0.05) abundant in both group of superstimulated cows compared to the control. In summary, ovarian superstimulation seems to modulate the PL content of bovine follicular fluid with a significant increase in PC (34:2), which jointly with others PC and SM, seems to offer a suitable biomarker involved with reproductive processes successful as ovary superstimulation response and embryo development.