Phosphatidylcholine and sphingomyelin profiles vary in Bos taurus indicus and Bos taurus taurus in vitro- and in vivo-produced blastocysts

Effects of sex on response of the bovine preimplantation embryo to insulin-like growth factor 1, activin A, and WNT7A

BACKGROUND

Alterations in maternal environment can sometimes affect embryonic development in a sexually-dimorphic manner. The objective was to determine whether preimplantation bovine embryos respond to three maternally-derived cell signaling molecules in a sex-dependent manner.

RESULTS

Actions of three embryokines known to increase competence of bovine embryos to develop to the blastocyst stage, insulin-like growth factor 1 (IGF1), activin A, and WNT member 7A (WNT7A), were evaluated for actions on embryos produced in vitro with X- or Y- sorted semen from the same bull. Each embryokine was tested in embryos produced by in vitro fertilization of groups of oocytes with either pooled sperm from two bulls or with sperm from individual bulls. Embryos were treated with IGF1, activin A, or WNT7A on day 5 of culture. All three embryokines increased the proportion of cleaved zygotes that developed to the blastocyst stage and the effect was similar for female and male embryos. As an additional test of sexual dimorphism, effects of IGF1 on blastocyst expression of a total of 127 genes were determined by RT-qPCR using the Fluidigm Delta Gene assay. Expression of 18 genes was affected by sex, expression of 4 genes was affected by IGF1 and expression of 3 genes was affected by the IGF1 by sex interaction.

CONCLUSION

Sex did not alter how IGF1, activin A or WNT7A altered developmental competence to the blastocyst stage. Thus, sex-dependent differences in regulation of developmental competence of embryos by maternal regulatory signals is not a general phenomenon. The fact that sex altered how IGF1 regulates gene expression is indicative that there could be sexual dimorphism in embryokine regulation of some aspects of embryonic function other than developmental potential to become a blastocyst.

Lipid droplets in clusters negatively affect Bos indicus embryos during cryopreservation

Embryo transfer using cryopreserved B. indicus embryos results in low pregnancy rates. The low viability of B. indicus embryos is likely a result of their low freezability relative to embryos from other species, notably B. taurus. Freezability is probably related to the quantity of lipid droplets in the embryonic cells. However, the mechanism underlying this association is unknown. Using multiphoton and transmission electron microscopy, the proportion, volume, morphology and composition of lipid droplets in fresh and cryopreserved B. indicus and B. taurus embryos were studied. B. indicus embryos have more droplets than B. taurus and a greater percentage of lipid droplets in clusters (34% vs. 24%; p < 0.05). Also, B. indicus individual droplets are of greater volume than those of B. taurus (47 μm³ vs. 34 μm³ ; p < 0.05). After freezing, the percentage of clusters decreased in B. indicus (11% vs. 5%; p < 0.05), while in B. taurus they increased (2% vs. 7%; p < 0.05). Freezing influenced the lipid droplet morphology, increasing the number of cracked droplets in B. indicus embryos (33% fresh vs. 62% frozen; p < 0.05), but not in B. taurus embryos (35% fresh vs. 34% frozen; ns). Regarding composition, saturated lipid droplets prevail in B. indicus embryos, contrary to B. taurus embryos. We observed differences in lipid droplet organization, proportion, volume, morphology and composition between B. indicus and B. taurus embryos which are altered in opposite directions following freezing.

Impact of l-carnitine on lipid content and post thaw survivability of buffalo embryos produced in vitro

The aim of the present study was to see the impact of L-Carnitine (LC) on lipid biosynthesis and metabolism of buffalo embryos, and post thaw blastocyst survivability. In vitro fertilized (IVF) embryos were derived from slaughterhouse derived COCs and cultured in different doses of LC i.e. 0, 1 mM, 1.5 mM, 2 mM starting at 48 h post IVF. Blastocyst rate was significantly (p < 0.05) higher in 1.5 mM group than control and 1.0 mM group. Lipid content was measured indirectly by fluorescent intensity of lipid droplets after Nile red staining, and it was lower (p < 0.05) in treated than control groups. CPT1B, DGAT2 and DGAT1 mRNA expression was up regulated (p < 0.05) while AMPKg1 expression was down regulated in 1.5 mM and 2 mM groups compared to other groups (p < 0.05). mRNA expression of GLUT1, OCT4 and IFN-tau was higher (P < 0.05) in 1.5 mM group than the control group. Expression of BAX was down regulated at 1.5 mM LC. Blastocyts were vitrified by a modified OPS method and post thaw survivability of blastocysts was higher (P < 0.05) in 1.5 mM LC than other groups. In post thaw blastocysts, mRNA expression of GLUT1, OCT4 and IFN-tau was higher (P < 0.05) in 1.5 mM than other groups. Thus, it can be concluded that supplementation of l-carnitine (1.5 mM) in embryo culture media improved the quality of buffalo embryo production and post thaw blastocysts survivability by reducing fatty acid synthesis, enhancing fatty acid metabolism, and reducing lipid droplet formation.

Supplementing in vitro embryo production media by NPPC and sildenafil affect the cytoplasmic lipid content and gene expression of bovine cumulus-oocyte complexes and embryos

In our study, we added natriuretic peptide type C (NPPC) and/or sildenafil during in vitro maturation (IVM) of bovine cumulus-oocyte complexes (COCs) followed by in vitro culture (IVC) of embryos with or without sildenafil. We evaluated the effects on the lipid content (LC) of oocytes and embryos and also verified the expression of 96 transcripts related to competence in matured COCs and 96 transcripts related to embryo quality in blastocysts. After IVM, LC was decreased in oocytes by NPPC while sildenafil did not affect LC in oocytes. The genes involved in lipid metabolism and lipid accumulation (DGAT1, PLIN2and PLIN3) were not affected in COCs after treatment during IVM, although the expression of PTX3 (a cumulus cells expansion biomarker) was increased and the hatched blastocyst rate was increased by NPPC during IVM. During IVM, sildenafil increased the mRNA relative abundance of HSF1 and PAF1 and decreased REST in blastocysts. The use of sildenafil in IVC increased the LC of blastocysts. The mRNA abundance in blastocysts produced during IVC with sildenafil was changed for ATF4, XBP1, DNMT3A, DNMT3B, COX2, and SOX2. Although NPPC reduced the LC of oocytes after IVM and upregulated markers for cumulus expansion, embryo production was not affected and the produced blastocysts were able to regain their LC after IVC. Finally, the use of sildenafil during IVC increased the cytoplasmic LC of embryos but did not affect embryo quality, as measured by analysis of 96 transcripts related to embryo quality.

Oleic acid in the modulation of oocyte and preimplantation embryo development

Potential reproductive effects are considered as the major aspect of biomolecules functionality in an organism. The recent identification of differential patterns of fatty acids across ovarian follicles and their association with levels of sexual maturity highlights the importance of these biomolecules. It is well known that fatty acids are highly diverse in terms of their functional properties. Oleic acid is chemically classified as an unsaturated omega-9 fatty acid. Besides serving as an important energy source, oleic acid is involved in metabolic and structural roles. Free and esterified oleic acids are compartmentalized into discrete extracellular fluids, cell organelles and found within the cytosol. This review summarizes the current knowledge on the contribution of oleic acid in regulating female fertility, particularly its involvement in female germ cell growth and development. Oleic acid has been identified as a blastomeric and post-cryopreservation survival biomarker in bovine. Several related studies have shown the critical role of oleic acid in counteracting the detrimental effects of saturated fatty acids and in paracrine support of oocyte development. Although available data are not ideally detailed, most data suggest that oleic acid can contribute to normal oocyte and preimplantation embryo development via mechanisms involving metabolic partitioning of fatty acids, change in the membrane structural organization, attenuation of oxidative stress and regulation of intracellular signalling. Thus, oleic acid may play a significant role in oocyte and early embryo development, suggesting that future studies should explore in more detail its potential effects on the physiopathology of female reproduction.

Efeito da adição do ácido linoleico conjugado no cultivo in vitro de embriões F1 Holandês x Zebu na sobrevivência pós-vitrificação

RESUMO Avaliou-se o efeito da adição do ácido linoleico conjugado (CLA) ao meio de cultivo in vitro na viabilidade pós-vitrificação de embriões F1 Holandês x Zebu. Foram utilizados três meios de cultivo: controle (n=340 oócitos): meio SOF e soro fetal bovino (SFB), sem o CLA; SFB+CLA (n=359 oócitos): meio SOF, SFB e CLA; CLA (n=339 oócitos): meio SOF e CLA, sem o SFB. Todos os blastocistos produzidos foram submetidos à vitrificação, pelo método de Open Pulled Straw. Quinze blastocistos de cada tratamento foram fixados para quantificação lipídica por coloração com Sudan Black B. Para avaliar a viabilidade embrionária, foi observada a capacidade de reexpansão e eclosão pós-aquecimento dos embriões (controle=27; SFB+CLA=30; CLA=17). Foram realizadas transferências em um ou dois embriões por receptora para avaliação da sobrevivência in vivo: T1 [receptoras que receberam um blastocisto (n=17 embriões, sendo controle=5, SFB+CLA=6 e CLA=6)]; T2 [receptoras que receberam dois blastocistos, (n= 54 embriões, sendo controle=18, SFB+CLA=14 e CLA=22)]. Não houve diferença nas taxas de clivagem (62,1%; 74,0%; 74,0% para controle; SFB+CLA; CLA, respectivamente), produção de blastocistos em relação aos clivados (59,7%; 47,7%; 38,3% para controle; SFB+CLA; CLA, respectivamente) e produção de blastocistos em relação ao total de oócitos (37,1%; 35,4%; 28,3% para controle; SFB+CLA; CLA, respectivamente) (P>0,05). Houve diminuição de gotículas lipídicas nos embriões cultivados em meio suplementado com CLA em relação aos embriões cultivados na presença do SFB e na ausência do CLA (P<0,05). A taxa de reexpansão foi maior no grupo controle (70,4%) em relação ao CLA (47,1%) e menor no grupo SFB+CLA (43,3%) (P<0,05). O CLA foi eficaz em reduzir a deposição de lipídeos intracitoplasmáticos nas células embrionárias, porém não houve diferença de viabilidade após a desvitrificação dos embriões.

Effect of soybean phosphatidylcholine on lipid profile of bovine oocytes matured in vitro

The phospholipid (PL) composition of embryo and oocyte membranes affects thermal phase behavior and several physicochemical properties such as fluidity and permeability. The characterization of PL profiles and the development of suitable in vitro maturation (IVM) protocols, that are able to modify membrane's composition, may result in significant improvements in oocyte developmental potential and cryotolerance. Using soybean phosphatidylcholine (PC) as a model supplement, we evaluated the effect of PL supplementation during IVM on bovine cumulus-oocyte-complex (COC). Substantial changes in the lipid profiles of oocyte membrane were observed and associated with pre-implantation data. The propensity of the PC supplement to become soluble in the maturation medium and/or diffuse into mineral oil was also assessed. Oocytes were matured in TCM without supplementation, i.e. control, (n=922) or supplemented with 50 or 100μM PC (n=994). The maturation media and mineral oil pre- and post- IVM, along with control and PC-treated oocytes were then analyzed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), and the lipid profiles were compared via principal component analysis (PCA). Soybean PCs are bioavailable and stable in IVM medium; further, PCs did not diffuse to the mineral oil, which also remained unaltered by the metabolism of treated oocytes. PC supplementation at 100μM resulted in substantially greater relative abundances of polyunsatured PL, namely PC (32:1), PC (34:2), PC (36:6), PC (36:4), and PC (38:6), in oocyte membrane. These differences indicated that short-term exposure to the PC supplement could indeed modify the lipid composition of IVM-oocytes in a dose-dependent manner. Membrane incorporation of polyunsaturated molecular species of PC was favored, and does so without compromising the viability of the subsequent embryo in regards to cleavage, blastocyst development and hatching rate. The reported approach will allow for the development of novel strategies to modulate oocyte membrane dynamics and structure.

Cryosurvival of in vitro produced bovine embryos supplemented with l-Carnitine and concurrent reduction of fatty acids

Lipid accumulation is associated with reduced embryonic quality, causing limited survival after cryopreservation. Therefore, in the present study we aimed to reveal the effects of supplementation of a lipid reducing agent, l-carnitine and the removal of fatty acids during in vitro culture on the morphological as well as on the molecular level. To accomplish that, presumptive zygotes were cultured in 4 contrasting groups: namely SOFaa medium supplemented with BSA, (BSA), SOFaa medium supplemented with fatty acid free BSA (FAF), SOFaa medium supplemented with BSA as well as l-Carnitine (BSA + LC) and SOFaa medium concurrently supplemented with fatty acid free BSA and l-Carnitine (FAF + LC). Considering the developmental rates, no impact of different treatments was observed. Conversely, treatment groups clearly affected lipid content, with the lowest amounts detected in embryos derived from FAF and BSA + LC groups, implicating that both removal of fatty acids and supplementation of LC reduces lipid content effectively. Importantly, survival rates after cryopreservation show that LC significantly affects the kinetics of re-expansion, with the highest hatching rates detected for embryos cultured in FAF + LC (p < 0.05). Noteworthy, the highest cryotolerance did not go along with lowest lipid contents. Finally, metabolic alterations between the groups were reflected in different abundances of selected candidate genes related to lipid metabolism and oxidative stress response, like AMPKA1, ACC and PGC1 α or KEAP1 and SOD1. All in all, highly beneficial effects on survival rates after cryopreservation have been detected when embryos were cultured in absence of fatty acids and concurrent presence of l-Carnitine. Highest cryotolerance, however, did not correlate with lowest lipid contents.

MALDI mass spectrometry reveals that cumulus cells modulate the lipid profile of in vitro-matured bovine oocytes

The influence of cumulus cells (CC) on the lipid profile of bovine oocytes matured in two different lipid sources was investigated. Cumulus-oocyte complexes (COC) or denuded oocytes (DO) were matured in tissue culture medium (TCM) supplemented with fetal bovine serum (FBS) or serum substitute supplement (SSS). Lipid profiles of TCM, serum supplements, immature CC and oocyte (IO), and in vitro-matured oocytes from COC and DO were then analyzed by matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) and submitted to partial least squares-discriminant analysis (PLS-DA). The developmental competence of such oocytes was also assessed. Differences in lipid composition were observed between two types of sera and distinctly influenced the lipid profile of CC. As revealed by PLS-DA, the abundance of specific ions corresponding to triacylglycerols (TAG) or phospholipids (PL) were higher in COC compared to DO both supplemented with FBS or SSS and to some extent affected the subsequent DO in vitro embryo development. DO exposed to SSS had however a marked diminished ability to develop to the blastocyst stage. These results indicate a modulation by CC of the oocyte TAG and PL profiles associated with a specific cell response to the serum supplement used for in vitro maturation.

Cell apoptosis and lipid content of in vitro-produced, vitrified bovine embryos treated with forskolin

The presence of fetal calf serum in culture medium influences embryo quality, causing a reduction in postcryopreservation survival. Forskolin has been used to induce lipolysis and increase cryotolerance, functioning as an activator of adenylate cyclase and elevating cAMP levels. In the present experiment, bovine zygotes were cultured in synthetic oviduct fluid with amino acid plus 2.5% fetal calf serum for 6 days, when forskolin was added in three concentrations: 2.5, 5, and 10 μM. Treatment with forskolin lasted for 24 hours. Blastocyst formation rate, quantification of lipid granules, total cell numbers, and apoptosis rate were evaluated. In a second assessment, embryos were vitrified, and warming, re-expansion rate, total cell numbers, and apoptosis rate were also evaluated. There was no difference due to forskolin in blastocyst formation or re-expansion rates after vitrification. However, lipid measurements were lower (control: 136.8 and F 2.5 μM: 128.5; P < 0.05), and number of cells per embryo higher (control: 140.1 and F 2.5 μM: 173.5; P < 0.05) than controls for 2.5 μM forskolin but not for higher forskolin concentrations. The number of intact cells per embryo was higher, and the rate of apoptosis was lower in fresh than in vitrified embryos (number of cells of warmed embryos, control: 104.1, F 2.5 μM: 101.3, F 5 μM: 115.4, F 10 μM: 95.1; apoptotic of fresh cells, control: 12.1%, F 2.5 μM: 16.7%, F 5 μM: 11.1%, F 10 μM: 14.2%; and apoptotic warmed embryos, control: 22.3%, F 2.5 μM: 37.3%, F 5 μM: 33.2%, F 10 μM: 30.3%; P < 0.05). It was concluded that forskolin is an effective lipolytic agent even at low concentrations, leading to formation of blastocysts with a comparatively larger number of cells.

Effects of n-6 and n-3 polyunsaturated acid-rich soybean phosphatidylcholine on membrane lipid profile and cryotolerance of human sperm

OBJECTIVE

To study the effects of n-6 and n-3 polyunsaturated acid-rich soybean phosphatidylcholine (soy-PC) on sperm cryotolerance with regard to sperm membrane lipid profile, membrane surface integrity, and routine semen parameters.

DESIGN

Experimental study.

SETTING

University-affiliated tertiary hospital.

PATIENT(S)

A total of 20 normospermic fertile men.

INTERVENTION(S)

Semen samples examined for differences in semen parameters, sperm membrane lipid profile, and plasma membrane surface both before and after cryopreservation using basic freezing medium with N-tris(hydroxymethyl)-methyl-2-aminoethane sulfonic acid (TES) and tris-(hydroxymethyl)-aminomethane (TRIS) supplemented with purified soy-PC (TEST-PC) or egg yolk (TEST-Y), both alone or in association (TEST-Y-PC).

MAIN OUTCOME MEASURE(S)

Conventional semen parameters and membrane lipid profile by matrix-assisted laser/desorption ionization mass spectrometry (MALDI-MS).

RESULT(S)

Postthaw sperm cell motility, vitality, and morphology parameters were similar for soy-PC (TEST-PC) and egg yolk (TEST-Y) cryoprotectants. However, sperm exposed to TEST-Y-PC presented better kinetic parameters, which were similar to the original quality of the fresh semen. Human sperm MALDI-MS lipid profiles revealed that the relative abundance of glycerophospholipids of m/z 760.44 [PC (34:1)+H]+, 781.55 [SM (20:0) +Na]+, 784.55 [PC (36:3) +H]+, 806.64 [PC (38:6) +H]+, 807.64 [SM (22:1) +Na]+, and 809.64 [SM (22:0) +Na]+ increased in soy-PC samples (TEST-PC). Nonetheless, only one lipid (m/z 781.55, [SM (20:0) +Na]+) statistically significantly changed when sperm was cryopreserved in TEST-Y-PC.

CONCLUSION(S)

Sphingomyelin was defined as a prospective biomarker of soy-PC treatment, and it could be related to the positive cryoprotective effects of soy-PC in human sperm, opening new perspectives to design of a more efficient synthetic cryoprotectant medium containing purified egg yolk biomolecules combined with soy-PC.

Visualization of sphingolipids and phospholipids in the fundic gland mucosa of human stomach using imaging mass spectrometry

AIM: To analyze the lipid distribution in gastric mucosae.

METHODS: Imaging mass spectrometry (MS) is a useful tool to survey the distribution of biomolecules in surgical specimens. Here we used the imaging MS apparatus named iMScope to identify the dominant molecules present in the human gastric mucosa near the fundic glands. Five gastric specimens were subjected to iMScope analysis. These specimens were also analyzed by immunohistochemistry using MUC5AC, H(+)-K(+)-ATPaseβ Claudin18 antibodies.

RESULTS: Three major molecules with m/z 725.5, 780.5, and 782.5 detected in the gastric mucosa were identified as sphingomyelin (SM) (d18:1/16:0), phosphatidylcholine (PC) (16:0/18:2), and PC (16:0/18:1), respectively, through MS/MS analyses. Using immunohistological staining, SM (d18:1/16:0) signals were mainly co-localized with the foveolar epithelium marker MUC5AC. In contrast, PC (16:0/18:2) signals were observed in the region testing positive for the fundic gland marker H(+)-K(+)-ATPaseβ. PC (16:0/18:1) signals were uniformly distributed throughout the mucosa.

CONCLUSION: Our basic data will contribute to the studies of lipid species in physical and pathological conditions of the human stomach.

Lipidome signatures in early bovine embryo development

Mammalian preimplantation embryonic development is a complex, conserved, and well-orchestrated process involving dynamic molecular and structural changes. Understanding membrane lipid profile fluctuation during this crucial period is fundamental to address mechanisms governing embryogenesis. Therefore, the aim of the present work was to perform a comprehensive assessment of stage-specific lipid profiles during early bovine embryonic development and associate with the mRNA abundance of lipid metabolism-related genes (ACSL3, ELOVL5, and ELOVL6) and with the amount of cytoplasmic lipid droplets. Immature oocytes were recovered from slaughterhouse-derived ovaries, two-cell embryos, and eight- to 16-cell embryos, morula, and blastocysts that were in vitro produced under different environmental conditions. Lipid droplets content and mRNA transcript levels for ACSL3, ELOVL5, and ELOVL6, monitored by lipid staining and quantitative polymerase chain reaction, respectively, increased at morula followed by a decrease at blastocyst stage. Relative mRNA abundance changes of ACSL3 were closely related to cytoplasmic lipid droplet accumulation. Characteristic dynamic changes of phospholipid profiles were observed during early embryo development and related to unsaturation level, acyl chain length, and class composition. ELOVL5 and ELOVL6 mRNA levels were suggestive of overexpression of membrane phospholipids containing elongated fatty acids with 16, 18, and 20 carbons. In addition, putative biomarkers of key events of embryogenesis, embryo lipid accumulation, and elongation were identified. This study provides a comprehensive description of stage-specific lipidome signatures and proposes a mechanism to explain its potential relationship with the fluctuation of both cytoplasmic lipid droplets content and mRNA levels of lipid metabolism-related genes during early bovine embryo development.

Detection and confirmation of serum lipid biomarkers for preeclampsia using direct infusion mass spectrometry

Despite substantial research, the early diagnosis of preeclampsia remains elusive. Lipids are now recognized to be involved in regulation and pathophysiology of some disease. Shotgun lipidomic studies were undertaken to determine whether serum lipid biomarkers exist that predict preeclampsia later in the same in pregnancy. A discovery study was performed using sera collected at 12-14 weeks pregnancy from 27 controls with uncomplicated pregnancies and 29 cases that later developed preeclampsia. Lipids were extracted and analyzed by direct infusion into a TOF mass spectrometer. MS signals, demonstrating apparent differences were selected, their abundances determined, and statistical differences tested. Statistically significant lipid markers were reevaluated in a second confirmatory study having 43 controls and 37 preeclampsia cases. Multi-marker combinations were developed using those lipid biomarkers confirmed in the second study. The initial study detected 45 potential preeclampsia markers. Of these, 23 markers continued to be statistically significant in the second confirmatory set. Most of these markers, representing several lipid classes, were chemically characterized, typically providing lipid class and potential molecular components using MS(2) Several multi-marker panels with areas under the curve >0.85 and high predictive values were developed. Developed panels of serum lipidomic biomarkers appear to be able to identify most women at risk for preeclampsia in a given pregnancy at 12-14 weeks gestation.

Effect of vitrification using the Cryotop method on the gene expression profile of in vitro-produced bovine embryos

The present study analyzed the changes in gene expression induced by the Cryotop vitrification technique in bovine blastocyst-stage embryos, using Agilent EmbryoGENE microarray slides. Bovine in vitro-produced embryos were vitrified and compared with nonvitrified (control) embryos. After vitrification, embryos were warmed and cultured for an additional 4 hours. Survived embryos were used for microarray analysis and quantitative polymerase chain reaction (qPCR) quantification. Survival rates were higher (P < 0.05) in the control embryos (100%) than in the vitrified embryos (87%). Global gene expression analysis revealed that only 43 out of 21,139 genes exhibited significantly altered expression in the vitrified embryos compared to the control embryos, with a very limited fold change (P < 0.05). A total of 10 genes were assessed by qPCR. Only the FOS-like antigen 1 (FOSL1) gene presented differential expression (P < 0.05) according to both the array and qPCR methods, and it was overexpressed in vitrified embryos. Although, the major consequence of vitrification seems to be the activation of the apoptosis pathway in some cells. Indeed, FOSL1 is part of the activating protein 1 transcription factor complex and is implicated in a variety of cellular processes, including proliferation, differentiation, and apoptosis. Therefore, our results suggest that a limited increase in the rate of apoptosis was the only detectable response of the embryos to vitrification stress.

Effects of Different Maturation Systems on Bovine Oocyte Quality, Plasma Membrane Phospholipid Composition and Resistance to Vitrification and Warming

The objective of this study was to evaluate the effects of different maturation systems on oocyte resistance after vitrification and on the phospholipid profile of the oocyte plasma membrane (PM). Four different maturation systems were tested: 1) in vitro maturation using immature oocytes aspirated from slaughterhouse ovaries (CONT; n = 136); 2) in vitro maturation using immature oocytes obtained by ovum pick-up (OPU) from unstimulated heifers (IMA; n = 433); 3) in vitro maturation using immature oocytes obtained by OPU from stimulated heifers (FSH; n = 444); and 4) in vivo maturation using oocytes obtained from heifers stimulated 24 hours prior by an injection of GnRH (MII; n = 658). A sample of matured oocytes from each fresh group was analyzed by matrix associated laser desorption-ionization (MALDI-TOF) to determine their PM composition. Then, half of the matured oocytes from each group were vitrified/warmed (CONT VIT, IMA VIT, FSH VIT and MII VIT), while the other half were used as fresh controls. Afterwards, the eight groups underwent IVF and IVC, and blastocyst development was assessed at D2, D7 and D8. A chi-square test was used to compare embryo development between the groups. Corresponding phospholipid ion intensity was expressed in arbitrary units, and following principal components analyses (PCA) the data were distributed on a 3D graph. Oocytes obtained from superstimulated animals showed a greater rate of developmental (P<0.05) at D7 (MII = 62.4±17.5% and FSH = 58.8±16.1%) compared to those obtained from unstimulated animals (CONT = 37.9±8.5% and IMA = 50.6±14.4%). However, the maturation system did not affect the resistance of oocytes to vitrification because the blastocyst rate at D7 was similar (P>0.05) for all groups (CONT VIT = 2.8±3.5%, IMA VIT = 2.9±4.0%, FSH VIT = 4.3±7.2% and MII VIT = 3.6±7.2%). MALDI-TOF revealed that oocytes from all maturation groups had similar phospholipid contents, except for 760.6 ([PC (34:1) + H]+), which was more highly expressed in MII compared to FSH (P<0.05). The results suggest that although maturation systems improve embryonic development, they do not change the PM composition nor the resistance of bovine oocytes to vitrification.

Cryotolerance and global gene-expression patterns of Bos taurus indicus and Bos taurus taurus in vitro- and in vivo-produced blastocysts

In a 2×2 factorial experimental design, embryo development, cryotolerance and global gene expression of Nellore (Bos taurus indicus) and Simmental (Bos taurus taurus) blastocysts produced in vitro (IVP) and in vivo (multiple ovulation derived embryo, MODE) were assessed. Blastocyst production was higher in Nellore than in Simmental (47.7±2.0% vs 27.0±2.0%) cows. The total numbers of ova or embryos recovered (5.5±0.9 vs 3.7±0.8) and transferable embryos (3.8±1.0 vs 2.3±0.8) per cow were not different between breeds. Simmental and MODE (34.6% and 38.5%, n=75 and 70) blastocysts had higher survival rates after cryopreservation compared with Nellore and IVP (20.2% and 18.1%, n=89 and 94) embryos, respectively. Differences between transcriptomes were addressed by principal-component analysis, which indicated that gene expression was affected by subspecies (158 genes), origin (532 genes) and interaction between both subspecies and origin (53 genes). Several functional processes and pathways relevant to lipid metabolism and embryo viability involving differentially expressed genes were identified. The lipid metabolism-related genes were upregulated in Simmental (AUH and ELOVL6) and IVP (ACSL3 and ACSL6) blastocysts. The expression profiles of genes related to mitochondrial metabolism (ATP5B), oxidative stress (GPX4), apoptosis (DAD1, DAP, PRDX2), heat shock (HSPA5), pregnancy (IFNT2, PAG2) and cell differentiation (KRT18) varied between experimental groups.

Developmental block and programmed cell death in Bos indicus embryos: effects of protein supplementation source and developmental kinetics

The aims of this study were to determine if the protein source of the medium influences zebu embryo development and if developmental kinetics, developmental block and programmed cell death are related. The culture medium was supplemented with either fetal calf serum or bovine serum albumin. The embryos were classified as Fast (n = 1,235) or Slow (n = 485) based on the time required to reach the fourth cell cycle (48 h and 90 h post insemination - hpi -, respectively). The Slow group was further separated into two groups: those presenting exactly 4 cells at 48 hpi (Slow/4 cells) and those that reached the fourth cell cycle at 90 hpi (Slow). Blastocyst quality, DNA fragmentation, mitochondrial membrane potential and signs of apoptosis or necrosis were evaluated. The Slow group had higher incidence of developmental block than the Fast group. The embryos supplemented with fetal calf serum had lower quality. DNA fragmentation and mitochondrial membrane potential were absent in embryos at 48 hpi but present at 90 hpi. Early signs of apoptosis were more frequent in the Slow and Slow/4 cell groups than in the Fast group. We concluded that fetal calf serum reduces blastocyst development and quality, but the mechanism appears to be independent of DNA fragmentation. The apoptotic cells detected at 48 hpi reveal a possible mechanism of programmed cell death activation prior to genome activation. The apoptotic cells observed in the slow-developing embryos suggested a relationship between programmed cell death and embryonic developmental kinetics in zebu in vitro-produced embryos.

Phospholipids of tumor extracellular vesicles stratify gefitinib-resistant nonsmall cell lung cancer cells from gefitinib-sensitive cells

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) such as gefitinib are one of gold standard treatment options for nonsmall-cell lung cancer (NSCLC) patients, which eventually fail due to the acquired resistance and relapse because of the development of secondary activating mutations such as T790M in EGFR. Predicting chemo-responsiveness of cancer patients provides a major challenge in chemotherapy. The goal of the present study is to determine whether phospholipid signatures of tumor extracellular vesicles (EV) are associated with gefitinib-resistance of NSCLC. A sophisticated MS-based shotgun lipidomic assays were performed for in-depth analysis of the lipidomes of gefitinib-resistant (PC9R) and responsive (PC9) NSCLC cells and their shed EV from these cell lines (PC9EV or PC9REV). Lipid MALDI-MS analysis showed that EV phospholipid composition was significantly distinct in PC9R, compared to PC9 cells. Following statistical analyses has identified 35 (20 positive and 15 negative ion mode) differentially regulated lipids, which are significantly over- or underexpressed in PC9R EV, compared to PC9 EV (p value < 0.01, fold change > 1.5). Our phospholipid signatures suggest that EV associates with drug sensitivity, which is worthy of additional investigation to assess chemoresistance in patients with NSCLC treated with anti-EGFR TKIs.

Breed-specific factors influence embryonic lipid composition: comparison between Jersey and Holstein

Some embryos exhibit better survival potential to cryopreservation than others. The cause of such a phenotype is still unclear and may be due to cell damage during cryopreservation, resulting from overaccumulation and composition of lipids. In cattle embryos, in vitro culture conditions have been shown to impact the number of lipid droplets within blastomeres. Thus far, the impact of breed on embryonic lipid content has not been studied. In the present study were compared the colour, lipid droplet abundance, lipid composition, mitochondrial activity and gene expression of in vivo-collected Jersey breed embryos, which are known to display poor performance post-freezing, with those of in vivo Holstein embryos, which have good cryotolerance. Even when housed and fed under the same conditions, Jersey embryos were found to be darker and contain more lipid droplets than Holstein embryos, and this was correlated with lower mitochondrial activity. Differential expression of genes associated with lipid metabolism and differences in lipid composition were found. These results show genetic background can impact embryonic lipid metabolism and storage.

Genetic influence on the reduction in bovine embryo lipid content by l-carnitine

The decreased rate of pregnancy obtained in cattle using frozen in vitro embryos compared with in vivo embryos has been associated with over-accumulation of intracellular lipid, which causes cell damage during cryopreservation. It is believed that the higher lipid content of blastomeres of bovine embryos produced in vitro results in darker-coloured cytoplasm, which could be a consequence of impaired mitochondrial function. In this study, l-carnitine was used as a treatment to reduce embryonic lipid content by increasing metabolism in cultured bovine embryos. We have observed previously that in vivo embryos of different dairy breeds collected from cows housed and fed under the same conditions differed in lipid content and metabolism. As such, breed effects between Holstein and Jersey were also examined in terms of general appearance, lipid composition, mitochondrial activity and gene expression. Adding l-carnitine to the embryo culture medium reduced the lipid content in both breeds due to increased mitochondrial activity. The response to l-carnitine was weaker in Jersey than in Holstein embryos. Our results thus show that genetics influence the response of bovine embryos to stimulation of mitochondrial metabolism.

Ambient ionisation mass spectrometry for lipid profiling and structural analysis of mammalian oocytes, preimplantation embryos and stem cells

Lipids play fundamental roles in mammalian embryo preimplantation development and cell fate. Triacylglycerol accumulates in oocytes and blastomeres as lipid droplets, phospholipids influence membrane functional properties, and essential fatty acid metabolism is important for maintaining the stemness of cells cultured in vitro. The growing impact that lipids have in the field of developmental biology makes analytical approaches to analyse structural information of great interest. This paper describes the concept and presents the results of lipid profiling by mass spectrometry (MS) of oocytes and preimplantation embryos, with special focus on ambient ionisation. Based on our previous experience with oocytes and embryos, we aim to convey that ambient MS is also valuable for stem cell differentiation analysis. Ambient ionisation MS allows the detection of a wide range of lipid classes (e.g. free fatty acids, cholesterol esters, phospholipids) in single oocytes, embryos and cell pellets, which are informative of in vitro culture impact, developmental and differentiation stages. Background on MS principles, the importance of underused MS scan modes for structural analysis of lipids, and statistical approaches used for data analysis are covered. We envisage that MS alone or in combination with other techniques will have a profound impact on the understanding of lipid metabolism, particularly in early embryo development and cell differentiation research.

Membrane lipid profile monitored by mass spectrometry detected differences between fresh and vitrified in vitro-produced bovine embryos

This study aimed to evaluate the impact of vitrification on membrane lipid profile obtained by mass spectrometry (MS) of in vitro-produced bovine embryos. Matrix-assisted laser desorption ionization–mass spectrometry (MALDI–MS) has been used to obtain individual embryo membrane lipid profiles. Due to conditions of analysis, mainly membrane lipids, most favorably phosphatidylcholines (PCs) and sphingomyelins (SMs) have been detected. The following ions described by their mass-to-charge ratio (m/z) and respective attribution presented increased relative abundance (1.2–20×) in the vitrified group: 703.5 [SM (16:0) + H]+; 722.5 [PC (40:3) + Na]+; 758.5 [PC (34:2) + H]+; 762.5 [PC (34:0) + H]+; 790.5 [PC (36:0) + H]+ and 810.5 [PC (38:4) + H]+ and/or [PC (36:1) + Na]+. The ion with a m/z 744.5 [PCp (34:1) and/or PCe (34:2)] was 3.4-fold more abundant in the fresh group. Interestingly, ions with m/z 722.5 or 744.5 indicate the presence of lipid species, which are more resistant to enzymatic degradation as they contain fatty acyl residues linked through ether type bonds (alkyl ether or plasmalogens, indicated by the lowercase ‘e’ and ‘p‘, respectively) to the glycerol structure. The results indicate that cryopreservation impacts the membrane lipid profile, and that these alterations can be properly monitored by MALDI-MS. Membrane lipids can therefore be evaluated by MALDI-MS to monitor the effect of cryopreservation on membrane lipids, and to investigate changes in lipid profile that may reflect the metabolic response to the cryopreservation stress or changes in the environmental conditions.

Fatty acid synthesis and oxidation in cumulus cells support oocyte maturation in bovine

Oocyte meiotic maturation requires energy from various substrates including glucose, amino acids, and lipids. Mitochondrial fatty acid (FA) β-oxidation (FAO) in the oocyte is required for meiotic maturation, which is accompanied by differential expression of numerous genes involved in FAs metabolism in surrounding cumulus cells (CCs) in vivo. The objective was to elucidate components involved in FAs metabolism in CCs during oocyte maturation. Twenty-seven genes related to lipogenesis, lipolysis, FA transport, and FAO were chosen from comparative transcriptome analysis of bovine CCs before and after maturation in vivo. Using real-time PCR, 22 were significantly upregulated at different times of in vitro maturation (IVM) in relation to oocyte meiosis progression from germinal vesicle breakdown to metaphase-II. Proteins FA synthase, acetyl-coenzyme-A carboxylase, carnitine palmitoyltransferase, perilipin 2, and FA binding protein 3 were detected by Western blot and immunolocalized to CCs and oocyte cytoplasm, with FA binding protein 3 concentrated around oocyte chromatin. By mass spectrometry, CCs lipid profiling was shown to be different before and after IVM. FAO inhibitors etomoxir and mildronate dose-dependently decreased the oocyte maturation rate in vitro. In terms of viability, cumulus enclosed oocytes were more sensitive to etomoxir than denuded oocytes. In CCs, etomoxir (150 μM) led to downregulation of lipogenesis genes and upregulated lipolysis and FAO genes. Moreover, the number of lipid droplets decreased, whereas several lipid species were more abundant compared with nontreated CCs after IVM. In conclusion, FAs metabolism in CCs is important to maintain metabolic homeostasis and may influence meiosis progression and survival of enclosed oocytes.

Analysis of the phospholipid profile of metaphase II mouse oocytes undergoing vitrification

Oocyte freezing confers thermal and chemical stress upon the oolemma and various other intracellular structures due to the formation of ice crystals. The lipid profiles of oocytes and embryos are closely associated with both, the degrees of their membrane fluidity, as well as the degree of chilling and freezing injuries that may occur during cryopreservation. In spite of the importance of lipids in the process of cryopreservation, the phospholipid status in oocytes and embryos before and after freezing has not been investigated. In this study, we employed mass spectrometric analysis to examine if vitrification has an effect on the phospholipid profiles of mouse oocytes. Freshly prepared metaphase II mouse oocytes were vitrified using copper grids and stored in liquid nitrogen for 2 weeks. Fresh and vitrified-warmed oocytes were subjected to phospholipid extraction procedure. Mass spectrometric analyses revealed that multiple species of phospholipids are reduced in vitrified-warmed oocytes. LIFT analyses identified 31 underexpressed and 5 overexpressed phospholipids in vitrified mouse oocytes. The intensities of phosphatidylinositol (PI) {18∶2/16∶0} [M-H]- and phosphatidylglycerol (PG) {14∶0/18∶2} [M-H]- were decreased the most with fold changes of 30.5 and 19.1 in negative ion mode, respectively. Several sphingomyelins (SM) including SM {d38∶3} [M+H]+ and SM {d34∶0} [M+K]+ were decreased significantly in positive ion mode. Overall, the declining trend of multiple phospholipids demonstrates that vitrification has a marked effect on phospholipid profiles of oocytes. These results show that the identified phospholipids can be used as potential biomarkers of oocyte undergoing vitrification and will allow for the development of strategies to preserve phospholipids during oocyte cryopreservation.

Prediction of pregnancy viability in bovine in vitro-produced embryos and recipient plasma with Fourier transform infrared spectroscopy

We analyzed embryo culture medium (CM) and recipient blood plasma using Fourier transform infrared (FTIR) metabolomics to predict pregnancy outcome. Individually cultured, in vitro-produced (IVP) blastocysts were transferred to recipients as fresh and vitrified-warmed. Spent CM and plasma samples were evaluated using FTIR. The discrimination capability of the classifiers was assessed for accuracy, sensitivity (pregnancy), specificity (nonpregnancy), and area under the receiver operator characteristic curve (AUC). Within all IVP fresh embryos (birth rate=52%), high AUC were obtained at birth, especially with expanded blastocysts (CM: 0.80±0.053; plasma: 0.89±0.034). The AUC of vitrified IVP embryos (birth rate = 31%) were 0.607±0.038 (CM, expanded blastocysts) and 0.672±0.023 (plasma, all stages). Recipient plasma generally predicted pregnancy outcome better than did embryo CM. Embryos and recipients with improved pregnancy viability were identified, which could increase the economic benefit to the breeding industry.

Differential expression of selected candidate genes in bovine embryos produced in vitro and cultured with chemicals modulating lipid metabolism

Lipid accumulated in embryos produced in vitro has been linked to reductions in both quality and postcryopreservation viability. Therefore, the objective of the present study was to investigate the influence of lipid-reducing chemicals on embryo development, quality, and postcryopreservation viability, in addition to expression profiles of selected lipid metabolism-regulating genes. Bovine cumulus-oocyte complexes were matured and fertilized in vitro; eight-cell stage embryos were cultured in IVC medium supplemented with phenazine ethosulfate (PES), L-carnitine (LC), PES + LC, or no supplementation (control). Culturing embryos in medium with LC increased (P < 0.05) blastocyst rate (38.8%) compared with the other groups (control = 28.1%, PES = 27.1%, PES + LC = 26.3%). Embryos cultured with supplements had greater total cell number and fewer apoptotic cells than the control. Cytoplasmic lipid content was reduced, whereas mitochondria density was increased in embryos treated with culture supplements; this was linked to altered expression profiles of selected genes regulating lipid metabolism. For example, transcript abundance of transmembrane lipid gene (SGPP1) was greater in LC- and PES-treated embryos, and they had increased postcryopreservation hatching ability (indicative of embryo cryotolerance). In conclusion, the two lipid metabolism regulators added to the culture media had improved embryo quality and cryotolerance, but embryo development rate and downstream lipid metabolism-regulating genes were more influenced with LC supplementation.

A diet enriched in linoleic acid compromises the cryotolerance of embryos from superovulated beef heifers

Dietary rumen-protected fat rich in linoleic acid may affect the superovulatory response and embryo yield; however, its effects on in vivo embryo cryotolerance are unknown in zebu cattle. The present study evaluated the production and cryotolerance after freezing or vitrification of embryos from Nelore heifers supplemented with rumen-protected polyunsaturated fatty acids (PUFA). Forty heifers kept in pasture were randomly distributed into two groups according to the type of feed supplement (F, supplement with rumen-protected PUFA, predominantly linoleic; C, control fat-free supplement with additional corn). Supplements were formulated to be isocaloric and isonitrogenous. Each heifer underwent both treatments in a crossover design with 70 days between replicates. After 50 days feeding, heifers were superovulated. Embryos were evaluated morphologically and vitrified or frozen. After thawing or warming, embryo development was evaluated in vitro. There was no difference between the F and C groups (P > 0.10) in terms of embryo production. Regardless of the cryopreservation method used, Group C embryos had a greater hatching rate after 72 h in vitro culture than Group F embryos (44.3 ± 4.2% (n = 148) vs 30.9 ± 4.0% (n = 137), respectively; P = 0.04). Moreover, vitrified and frozen embryos had similar hatching rates (P > 0.10). In conclusion, dietary rumen-protected PUFA rich in linoleic acid did not improve embryo production and compromised the cryotolerance of conventionally frozen or vitrified embryos from Nelore heifers.

Consequences of transfer of an in vitro-produced embryo for the dam and resultant calf

No reports exist on consequences of in vitro production (IVP) of embryos for the postnatal development of the calf or on postparturient function of the dam of the calf. Three hypotheses were evaluated: calves born as a result of transfer of an IVP embryo have reduced neonatal survival and altered postnatal growth, fertility, and milk yield compared with artificial insemination (AI) calves; cows giving birth to IVP calves have lower milk yield and fertility and higher incidence of postparturient disease than cows giving birth to AI calves; and the medium used for IVP affects the incidence of developmental abnormalities. In the first experiment, calves were produced by AI using conventional semen or by embryo transfer (ET) using a fresh or vitrified embryo produced in vitro with X-sorted semen. Gestation length was longer for cows receiving a vitrified embryo than for cows receiving a fresh embryo or AI. The percentage of dams experiencing calving difficulty was higher for ET than AI. We observed a tendency for incidence of retained placenta to be higher for ET than AI but found no significant effect of treatment on incidence of prolapse or metritis, pregnancy rate at first service, services per conception, or any measured characteristic of milk production in the subsequent lactation. Among Holstein heifers produced by AI or ET, treatment had no effect on birth weight but the variance tended to be greater in the ET groups. More Holstein heifer calves tended to be born dead, died, or were euthanized within the first 20d of life for the ET groups than for AI. Similarly, the proportion of Holstein heifer calves that either died or were culled for poor health after 20d of age was greater for the ET groups than for AI. We observed no effect of ET compared with AI on age at first service or on the percentage of heifers pregnant at first service, calf growth, or milk yield or composition in the first 120d in milk of the first lactation. In a second experiment, embryos were produced using 1 of 2 culture media: synthetic oviductal fluid-bovine embryo 1 (SOF-BE1) or Block-Bonilla-Hansen 7 (BBH7). We detected no difference between cows receiving an SOF-BE1 or BBH7 embryo in gestation length, the percentage of cows in which parturition was induced, or the percentage of cows that experienced calving difficulty, retained placenta, prolapse, or metritis. Among Holstein heifers, birth weight was higher for BBH7 calves than for SOF-BE1 calves. Treatment had no significant effect on calf death. Results indicate that calves born as a result of IVP-ET are more likely to experience alterations in birth weight and increased death in early life but that there were few consequences to the dam of carrying a fetus derived by IVP-ET.

Optimal single-embryo mass spectrometry fingerprinting

In pre-implantation embryos, lipids play key roles in determining viability, cryopreservation and implantation properties, but often their analysis is analytically challenging because of the few picograms of analytes present in each of them. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) allows obtaining individual phospholipid profiles of these microscopic organisms. This technique is sensitive enough to enable analysis of individual intact embryos and monitoring the changes in membrane lipid composition in the early stages of development serving as screening method for studies of biology and biotechnologies of reproduction. This article introduces an improved, more comprehensive MALDI-MS lipid fingerprinting approach that considerably increases the lipid information obtained from a single embryo. Using bovine embryos as a biological model, we have also tested optimal sample storage and handling conditions before the MALDI-MS analysis. Improved information at the molecular level is provided by the use of a binary matrix that enables phosphatidylcholines, sphingomyelins, phosphatidylserines, phosphatidylinositols and phosphoethanolamines to be detected via MALDI(±)-MS in both the positive and negative ion modes. An optimal MALDI-MS protocol for lipidomic monitoring of a single intact embryo is therefore reported with potential applications in human and animal reproduction, cell development and stem cell research.