TY - JOUR
T1 - Human meiotic progression and recombination are affected by Bisphenol A exposure during in vitro human oocyte development
AU - Brieño-Enríquez, M. A.
AU - Robles, P.
AU - Camats-Tarruella, N.
AU - García-Cruz, R.
AU - Roig, I.
AU - Cabero, L.
AU - Martínez, F.
AU - Caldés, M. Garcia
N1 - Funding Information:
Financial support for this study was provided by grants from the Min-isterio de Educación y Cultura (BFU2006–12951) (Spain), CIDEM (ACC1ó) Generalitat de Catalunya (Spain), Generalitat de Catalunya (2009 SGR 1107) (Spain), Ministerio de Asuntos Exteriores y Coop-eración Internacional (AECI, Spain) (#0000447445), National Council of Science and Technology (CONACYT, México) (#166825) and National Council of Public Education (SEP, México) (SEP-2004-COI-4591). The Ministerio de Educación y Cultura, CIDEM, Ministerio de Asuntos Exteriores y Coperación Internacional, National Council of Science and Technology and the National Council of Public Education had no role in the design, in data collection and analysis, decision to publish or preparation and interpretation of the manuscript.
PY - 2011/10
Y1 - 2011/10
N2 - Background Bisphenol A (BPA) is a 'weak' endocrine disruptor. The effect of BPA on human reproduction is controversial but has been related to meiotic anomalies, recurrent miscarriages and abnormal karyotypes. Methods To evaluate the effects of BPA on survival, pairing-synapsis and meiotic recombination of human fetal oocytes, 21 510 oocytes from 12 cultured fetal ovaries were analyzed. Ovaries were cultured for 7, 14 or 21 days in control medium, dimethylsulfoxide-medium, BPA-medium and estradiol (E 2 )-medium. Meiotic pairing-synapsis and recombination were studied by immunofluorescence against lateral element protein, central element protein of the synaptonemal complex and chromosome axis cohesin REC8. Mismatch repair protein, MLH1, was used as a crossover (CO) marker. Meiotic progression was analyzed following the number of surviving oocytes at different meiotic stages found in each culture time and condition, and the total number of MLH1 foci found in oocytes from cultured ovaries. Results Oocyte survival in vitro decreased with the addition of BPA to the medium (1 μM or greater). Oocyte degeneration was up to five times higher when BPA was added to culture medium. Moreover, oocytes exposed to BPA concentrations of 10 μM or higher presented approximately two times more MLH1 foci than unexposed cultured oocytes (P = 0.01). This was also observed in chromosome 21 from BPA-exposed oocytes, which had double the average number of MLH1 foci found in control oocytes (P = 0.001). E 2 was used as a positive control of estrogen receptors activity, and E 2 addition to the medium had similar effects on meiotic progression of oocytes from cultured ovaries. Conclusions Our findings show that BPA concentrations of 1 μM or higher decrease the survival of human fetal oocytes in vitro, and concentrations of 10 μM or higher increase MLH1 foci number. MLH1 is considered a CO marker, and thus an increase in MLH1 foci could indicate an increase in COs in BPA-exposed oocytes. These data suggest that BPA can act as a toxic substance, which has particular implications for human females and the critical events of meiotic prophase, such as pairing-synapsis and recombination processes, as well as oocyte survival. © 2011 The Author.
AB - Background Bisphenol A (BPA) is a 'weak' endocrine disruptor. The effect of BPA on human reproduction is controversial but has been related to meiotic anomalies, recurrent miscarriages and abnormal karyotypes. Methods To evaluate the effects of BPA on survival, pairing-synapsis and meiotic recombination of human fetal oocytes, 21 510 oocytes from 12 cultured fetal ovaries were analyzed. Ovaries were cultured for 7, 14 or 21 days in control medium, dimethylsulfoxide-medium, BPA-medium and estradiol (E 2 )-medium. Meiotic pairing-synapsis and recombination were studied by immunofluorescence against lateral element protein, central element protein of the synaptonemal complex and chromosome axis cohesin REC8. Mismatch repair protein, MLH1, was used as a crossover (CO) marker. Meiotic progression was analyzed following the number of surviving oocytes at different meiotic stages found in each culture time and condition, and the total number of MLH1 foci found in oocytes from cultured ovaries. Results Oocyte survival in vitro decreased with the addition of BPA to the medium (1 μM or greater). Oocyte degeneration was up to five times higher when BPA was added to culture medium. Moreover, oocytes exposed to BPA concentrations of 10 μM or higher presented approximately two times more MLH1 foci than unexposed cultured oocytes (P = 0.01). This was also observed in chromosome 21 from BPA-exposed oocytes, which had double the average number of MLH1 foci found in control oocytes (P = 0.001). E 2 was used as a positive control of estrogen receptors activity, and E 2 addition to the medium had similar effects on meiotic progression of oocytes from cultured ovaries. Conclusions Our findings show that BPA concentrations of 1 μM or higher decrease the survival of human fetal oocytes in vitro, and concentrations of 10 μM or higher increase MLH1 foci number. MLH1 is considered a CO marker, and thus an increase in MLH1 foci could indicate an increase in COs in BPA-exposed oocytes. These data suggest that BPA can act as a toxic substance, which has particular implications for human females and the critical events of meiotic prophase, such as pairing-synapsis and recombination processes, as well as oocyte survival. © 2011 The Author.
KW - BPA
KW - human fetal oocyte
KW - meiosis
KW - recombination
UR - http://www.scopus.com/inward/record.url?scp=80052884683&partnerID=8YFLogxK
U2 - 10.1093/humrep/der249
DO - 10.1093/humrep/der249
M3 - Article
VL - 26
SP - 2807
EP - 2818
IS - 10
ER -