Effects of electric field on early preimplantation development in vitro in mice and rats

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Elena Popova, Michael Bader* and Alexander Krivokharchenko

Max-Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Str. 10, D-13125 Berlin-Buch, Germany *Correspondence address. Fax: +49-30-9406-2110; E-mail: mbader{at}mdc-berlin.deReceived October 6, 2010. Revision received November 30, 2010. Accepted December 7, 2010. BACKGROUND Exposure of cells to electric fields is a commonly used technique for parthenogenesis, cloning and tetraploid embryo production. However, little is known about possible detrimental effects of electric fields on embryos and their development. The aim of this study was to investigate the effects of electric fields on early preimplantation development in mice and rats.

METHODS Mouse and rat metaphase II (MII) and pre-activated oocytes, zygotes and 2-cell stage embryos were treated with electric fields with increasing voltage. Cleavage rate, morula and blastocyst formation were evaluated by in vitro cultivation. The effects of electric fields on embryos were investigated by measurement of reactive oxygen species (ROS) content and microtubule and microfilament distributions using fluorescence staining.

RESULTS Pre-activated oocytes at the pronuclear stage and zygotes are more resistant to electric exposure than freshly isolated oocytes at MII stage in both studied species. Rat zygotes treated with electric fields of increasing voltage showed higher cleavage rates compared with the mouse and some of them developed beyond 4-cell stage in vitro. Embryos blocked at the 2-cell stage after in vitro cultivation of zygotes exposed to electric fields demonstrated increased level of ROS but normal distributions of microtubules and microfilaments. In both species, embryos at the 2-cell stage were more resistant to electric fields because they formed tetraploid embryos after electric field-induced blastomere fusion and these embryos could develop in vitro until the blastocyst stage.

CONCLUSIONS There are stage-dependent and species-specific differences in sensitivity to electric fields in mouse and rats.

© The Author 2011. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com This ArticleHum. Reprod. (2011) 26 (3): 662-670. doi: 10.1093/humrep/deq379 First published online: January 11, 2011

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Dietary iron intake during early pregnancy and birth outcomes in a cohort of British women

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Nisreen A. Alwan1,*, Darren C. Greenwood2, Nigel A.B. Simpson3, Harry J. McArdle4, Keith M. Godfrey5,6 and Janet E. Cade1

1Nutritional Epidemiology Group, Centre for Epidemiology and Biostatistics, School of Food Science and Nutrition, University of Leeds, Leeds, LS2 9JT, UK

2Division of Biostatistics, Centre for Epidemiology and Biostatistics, University of Leeds, Leeds, UK

3Department of Obstetrics and Gynaecology, University of Leeds, Leeds, UK

4Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK

5MRC Lifecourse Epidemiology Unit, Southampton, UK

6NIHR Nutrition, Diet & Lifestyle Biomedical Research Unit, Southampton, UK *Correspondence address. Tel: +44-113-343-6990; Fax: +44-113-343-4877; E-mail: n.alwan{at}leeds.ac.ukReceived October 10, 2010. Revision received November 13, 2010. Accepted December 20, 2010. BACKGROUND Iron deficiency during pregnancy is associated with adverse birth outcomes, particularly, if present during early gestation. Iron supplements are widely recommended during pregnancy, but evidence of their benefit in relation to infant outcomes is not established. This study was performed in the UK, where iron supplements are not routinely recommended during pregnancy, to investigate the association between iron intake in pregnancy and size at birth.

METHODS From a prospective cohort of 1274 pregnant women aged 18–45 years, dietary intake was reported in a 24-h recall administered by a research midwife at 12-week gestation. Dietary supplement intake was ascertained using dietary recall and three questionnaires in the first, second and third trimesters.

RESULTS Of the cohort of pregnant women, 80% reported dietary iron intake below the UK Reference Nutrient Intake of 14.8 mg/day. Those reported taking iron-containing supplements in the first, second and third trimesters were 24, 15 and 8%, respectively. Women with dietary iron intake >14.8 mg/day were more likely to be older, have a higher socioeconomic profile and take supplements during the first trimester. Vegetarians were less likely to have low dietary iron intake [odds ratio = 0.5, 95% confidence interval (CI): 0.4, 0.8] and more likely to take supplements during the first and second trimesters. Total iron intake, but not iron intake from food only, was associated with birthweight centile (adjusted change = 2.5 centiles/10 mg increase in iron, 95% CI: 0.4, 4.6). This association was stronger in the high vitamin C intake group, but effect modification was not significant.

CONCLUSION There was a positive relationship between total iron intake, from food and supplements, in early pregnancy and birthweight. Iron intake, both from diet and supplements, during the first trimester of pregnancy was higher in vegetarians and women with a better socioeconomic profile.

© The Author 2011. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology.This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.5), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

This ArticleHum. Reprod. (2011) 26 (4): 911-919. doi: 10.1093/humrep/der005 First published online: February 7, 2011

Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.

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