Cathepsin mRNA level in bovine cumulus cells fails to be a good marker of oocyte quality

Cathepsins (CTS) are lysosomal cysteine proteinases, of which elevated transcript content is attributed to the reduced quality of oocytes. The aim of this study was to investigate whether transcript content of three CTS genes in cumulus cells (CC) may be related to oocyte quality. The relationships between mRNA content of CTS genes in CC, the fatty acids profile in follicular fluid (FF) and selected quality traits of the corresponding oocyte (COC morphology, follicle diameter, mtDNA copy number) were investigated. Although an increased RA of the CTSB and the CTSK genes was accompanied by inferior COC morphology, it was also correlated with a higher mtDNA copy number in the oocyte and an increased content of C18.3n3 and n3 in FF. The last two traits were attributed to better quality oocytes, which contrasts with the high RA of the CTS genes. In conclusion, elevated transcript levels of CTS genes within CC are of limited value as an indicator of reduced quality in bovine oocytes. We suggest that the possible reason for the ambiguity of the obtained data could be the origin of cumulus cells within the COC, which may prove to be crucial for this type of studies

Species and embryo genome origin affect lipid droplets in preimplantation embryos

Mammalian embryo development is affected by multiple metabolism processes, among which energy metabolism seems to be crucial. Therefore the ability and the scale of lipids storage in different preimplantation stages might affect embryos quality. The aim of the present studies was to show a complex characterization of lipid droplets (LD) during subsequent embryo developmental stages. It was performed on two species (bovine and porcine) as well as on embryos with different embryo origin [after in vitro fertilization (IVF) and after parthenogenetic activation (PA)]. Embryos after IVF/PA were collected at precise time points of development at the following stages: zygote, 2-cell, 4-cell, 8/16-cell, morula, early blastocyst, expanded blastocyst. LD were stained with BODIPY 493/503 dye, embryos were visualized under a confocal microscope and images were analyzed with the ImageJ Fiji software. The following parameters were analyzed: lipid content, LD number, LD size and LD area within the total embryo. The most important results show that lipid parameters in the IVF vs. PA bovine embryos differ at the most crucial moments of embryonic development (zygote, 8–16-cell, blastocyst), indicating possible dysregulations of lipid metabolism in PA embryos. When bovine vs. porcine species are compared, we observe higher lipid content around EGA stage and lower lipid content at the blastocyst stage for bovine embryos, which indicates different demand for energy depending on the species. We conclude that lipid droplets parameters significantly differ among developmental stages and between species but also can be affected by the genome origin

Cathepsin mRNA level in bovine cumulus cells fails to be a good marker of oocyte quality

Cathepsins (CTS) are lysosomal cysteine proteinases, of which elevated transcript content is attributed to the reduced quality of oocytes. The aim of this study was to investigate whether transcript content of three CTS genes in cumulus cells (CC) may be related to oocyte quality. The relationships between mRNA content of CTS genes in CC, the fatty acids profile in follicular fluid (FF) and selected quality traits of the corresponding oocyte (COC morphology, follicle diameter, mtDNA copy number) were investigated. Although an increased RA of the CTSB and the CTSK genes was accompanied by inferior COC morphology, it was also correlated with a higher mtDNA copy number in the oocyte and an increased content of C18.3n3 and n3 in FF. The last two traits were attributed to better quality oocytes, which contrasts with the high RA of the CTS genes. In conclusion, elevated transcript levels of CTS genes within CC are of limited value as an indicator of reduced quality in bovine oocytes. We suggest that the possible reason for the ambiguity of the obtained data could be the origin of cumulus cells within the COC, which may prove to be crucial for this type of studies.This article is published as Warzych E., Cieslak A., Wolc A., Lechniak D. 2016. Cathepsins mRNA level in bovine cumulus cells fail to be a good marker for oocyte quality. Animal Science Papers and Reports 34:339-349.</p

Response of Bovine Cumulus–Oocytes Complexes to Energy Pathway Inhibition during In Vitro Maturation

Glucose or fatty acids (FAs) metabolisms may alter the ovarian follicle environment and thus determine oocyte and the nascent embryo quality. The aim of the experiment was to investigate the effect of selective inhibition of glucose (iodoacetate + DHEA) or FA (etomoxir) metabolism on in vitro maturation (IVM) of bovine COCs (cumulus–oocyte complexes) to investigate oocyte’s development, quality, and energy metabolism. After in vitro fertilization, embryos were cultured to the blastocyst stage. Lipid droplets, metabolome, and lipidome were analyzed in oocytes and cumulus cells. mRNA expression of the selected genes was measured in the cumulus cells. ATP and glutathione relative levels were measured in oocytes. Changes in FA content in the maturation medium were evaluated by mass spectrometry. Our results indicate that only glucose metabolism is substantial to the oocyte during IVM since only glucose inhibition decreased embryo culture efficiency. The most noteworthy differences in the reaction to the applied inhibition systems were observed in cumulus cells. The upregulation of ketone body metabolism in the cumulus cells of the glucose inhibition group suggest possibly failed attempts of cells to switch into lipid consumption. On the contrary, etomoxir treatment of the oocytes did not affect embryo development, probably due to undisturbed metabolism in cumulus cells. Therefore, we suggest that the energy pathways analyzed in this experiment are not interchangeable alternatives in bovine COCs

The

quality of porcine oocytes is affected by sexual maturity of the donor gil

Multifactorial Analysis of the Follicular Environment is Predictive of Oocyte Morphology in Cattle

Numerous attempts have been recently made in the search for a reliable, fast and noninvasive assay for selection of oocytes suitable for in vitro embryo production. Potential markers have been described in the follicle such as follicular fluid (FF) or cumulus cells (CCs). However, the reported findings are contradictory, which may reflect the complexity of metabolism of the ovarian follicle. In the present experiment, a data set from individual follicles of known diameter was obtained: cumulus-oocyte complex (COC) morphology, fatty acid composition and glucose concentration in FF as well as apoptotic index in CCs. The obtained data was statistically analyzed either separately (univariate analysis) or simultaneously (multivariate analysis) to examine its predictive value in morphology assessment of bovine COCs. Although the univariate analysis yielded a complex relation system of the selected parameters, no clear outcome could be established. In multivariate analysis, the concentration of the four fatty acids (C16:0, C16:1, C18:1cis9, C22:5n3) and Δ9-desaturase (16) as well as elongase activities were selected as covariates. This allowed prediction of the morphology of a COC with an accuracy of 72%, which is the most interesting finding of the experiment. The present study indicates that the multifactorial model comprising of selected parameters related to the follicle appeared more effective in predicting the morphology of a bovine COC, which may improve the effectiveness of in vitro production systems.This article is published as Warzych, Ewelina, Adam Cieslak, Zofia E. Madeja, Piotr Pawlak, Anna Wolc, and Dorota Lechniak. "Multifactorial analysis of the follicular environment is predictive of oocyte morphology in cattle." Journal of Reproduction and Development 60 (2014): 1-8. doi: 10.1262/jrd.2013-086.</p

Multifactorial Analysis of the Follicular Environment is Predictive of Oocyte Morphology in Cattle

Numerous attempts have been recently made in the search for a reliable, fast and noninvasive assay for selection of oocytes suitable for in vitro embryo production. Potential markers have been described in the follicle such as follicular fluid (FF) or cumulus cells (CCs). However, the reported findings are contradictory, which may reflect the complexity of metabolism of the ovarian follicle. In the present experiment, a data set from individual follicles of known diameter was obtained: cumulus-oocyte complex (COC) morphology, fatty acid composition and glucose concentration in FF as well as apoptotic index in CCs. The obtained data was statistically analyzed either separately (univariate analysis) or simultaneously (multivariate analysis) to examine its predictive value in morphology assessment of bovine COCs. Although the univariate analysis yielded a complex relation system of the selected parameters, no clear outcome could be established. In multivariate analysis, the concentration of the four fatty acids (C16:0, C16:1, C18:1cis9, C22:5n3) and Δ(9)-desaturase (16) as well as elongase activities were selected as covariates. This allowed prediction of the morphology of a COC with an accuracy of 72%, which is the most interesting finding of the experiment. The present study indicates that the multifactorial model comprising of selected parameters related to the follicle appeared more effective in predicting the morphology of a bovine COC, which may improve the effectiveness of in vitro production systems