Navegando por Palavras-chave "oocyte"

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    PHYSIOLOGY and ENDOCRINOLOGY SYMPOSIUM: Influence of cattle genotype (Bos indicus vs. Bos taurus) on oocyte and preimplantation embryo resistance to increased temperature
    (Amer Soc Animal Science, 2013-03-01) Paula-Lopes, F. F. [UNIFESP]; Lima, R. S.; Satrapa, R. A.; Barros, C. M.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    High environmental temperatures during the hot months of the year reduce reproductive performance in cattle. Summer heat stress depression in fertility is a multifactorial problem; however, there is evidence that the bovine germinal vesicle and maturing oocyte, as well as the early embryo, are major targets of the deleterious effects of heat stress. Such adverse effects are less pronounced in heat-tolerant breeds (Bos indicus) than heat-sensitive breeds (Bos taurus). This genetic variation results from the greater thermoregulatory ability and cellular thermoresistance of heat-tolerant breeds. Heat-induced oocyte cellular damage occurs in both cytoplasmic and nuclear compartments. Heat shock has been shown to reduce oocyte nuclear maturation, induce apoptosis, compromise oocyte cytoskeleton, and impair oocyte mitochondrial function and developmental competence. However, the oocyte cytoplasm is more susceptible to heat shock than the nucleus. This effect is greater for Bos taurus than Bos indicus oocytes. the detrimental effects of heat shock are also critical during the first cleavage divisions when most of the embryonic genome is inactive; however, the bovine embryo becomes more resistant to increased temperature as it proceeds through development. Several studies demonstrated that Bos indicus embryos are more thermotolerant than Bos taurus embryos. Adaptive changes involved in acquisition of thermotolerance are likely derived from changes in gene expression and (or) activity of biochemical molecules that control cellular functions against stress. Recently, molecules such as IGF-I and caspase inhibitor z-DEVD-fmk have been shown to exert a thermoprotective role, rescuing heat-induced oocyte and embryo cellular damage and developmental competence. Therefore, cattle genotype and thermoprotective molecules can be considered as an alternative to modulate the effects of increased temperature in reproductive function. (C) 2013 American Society of Animal Science. All rights reserved.
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    Single embryo and oocyte lipid fingerprinting by mass spectrometry
    (Amer Soc Biochemistry Molecular Biology Inc, 2010-05-01) Ferreira, Christina R.; Saraiva, Sergio A.; Catharino, Rodrigo R.; Garcia, Jerusa S.; Gozzo, Fabio C.; Sanvido, Gustavo B.; Santos, Luiz Fernando A.; Lo Turco, Edson G. [UNIFESP]; Pontes, Jose Henrique F.; Basso, Andrea C.; Bertolla, Ricardo P. [UNIFESP]; Sartori, Roberto; Guardieiro, Monique M.; Perecin, Felipe; Meirelles, Flvio V.; Sangalli, Juliano R.; Eberlin, Marcos N.; Universidade Estadual de Campinas (UNICAMP); Universidade Federal de São Paulo (UNIFESP); Vitro Brasil Ltda; Universidade de São Paulo (USP)
    Methods used for lipid analysis in embryos and oocytes usually involve selective lipid extraction from a pool of many samples followed by chemical manipulation, separation and characterization of individual components by chromatographic techniques. Herein we report direct analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of single and intact embryos or oocytes from various species. Biological samples were simply moisturized with the matrix solution and characteristic lipid ( represented by phosphatidylcholines, sphingomyelins and triacylglycerols) profiles were obtained via MALDI-MS. As representative examples, human, bovine, sheep and fish oocytes, as well as bovine and insect embryos were analyzed. MALDI-MS is shown to be capable of providing characteristic lipid profiles of gametes and embryos and also to respond to modifications due to developmental stages and in vitro culture conditions of bovine embryos. Investigation in developmental biology of the biological roles of structural and reserve lipids in embryos and oocytes should therefore benefit from these rapid MALDI-MS profiles from single and intact species.-Ferreira, C. R., S. A. Saraiva, R. R. Catharino, J. S. Garcia, F. C. Gozzo, G. B. Sanvido, L. F. A. Santos, E. G. Lo Turco, J. H. F. Pontes, A. C. Basso, R. P. Bertolla, R. Sartori, M. M. Guardieiro, F. Perecin, F. V. Meirelles, J. R. Sangalli, and M. N. Eberlin. Single embryo and oocyte lipid fingerprinting by mass spectrometry. J. Lipid Res. 2010. 51: 1218-1227.
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    Theoretical and experimental basis of oocyte vitrification
    (Elsevier B.V., 2011-09-01) Smith, Gary D.; Motta, Eduardo E. [UNIFESP]; Serafini, Paulo; Univ Michigan; Huntington Ctr Reprod Med Brazil; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    In the last decades significant advances have been made in successful cryopreservation of mammalian oocytes. Human oocyte cryopreservation has practical application in preserving fertility for individuals at risk of compromised egg quality due to cancer treatments or advanced maternal age. While oocyte cryopreservation success has increased over time, there is still room for improvement. Oocytes are susceptible to cryodamage; which collectively entails cellular damage caused by mechanical, chemical or thermal forces during the vitrification and warming process. This review will delineate many of the oocyte intracellular and extracellular structures that are/may be stressed and/or compromised during cryopreservation. This will be followed by a discussion of the theoretical basis of oocyte vitrification and warming, and a non-exhaustive review of current experimental data and clinical expectations of oocyte vitrification will be presented. Finally, a forward-thinking vision of a potential means of modifying and improving vitrification and warming procedures and success will be proposed. (C) 2011, Reproductive Healthcare Ltd. Published by Elsevier B.V. All rights reserved.