Embryonic resistance to chemical and physical factors: manifestation, mechanism, role in reproduction and in adaptation to ecology

Lethality of inappropriate plasma exposure on chicken embryonic development

In this study, we examined the effects of non-thermal dielectric barrier discharge plasma on embryonic development in chicken eggs in order to determine the optimal level of plasma exposure for the promotion of embryonic growth. We exposed developing chicken embryos at either Hamburger-Hamilton (HH) stage 04 or HH 20 to plasma at voltages of 11.7 kV to 27.6 kV. Our results show exposure at 11.7 kV for 1 min promoted chicken embryonic development, but exposure to more duration and intensity of plasma resulted in dose-dependent embryonic death and HH 20 stage embryos survive longer than those at stage HH 04. Furthermore, plasma exposure for 4 min increased the production of reactive oxygen species (ROS) and inactivated the nuclear factor erythroid 2-related factor 2 (NRF2)-antioxidant response signaling pathway, resulting in suppression of antioxidant enzymes in the skeletal muscle tissue of the dead embryos. We also found decreased levels of adenosine triphosphate production and reductions in the expression levels of several growth-related genes and proteins. These findings indicate that inappropriate plasma exposure causes dose-dependent embryonic death via excessive accumulation of ROS, NRF2-antioxidant signaling pathway disruption, and decreased growth factor expression.

The seasonal conception of lethal congenital malformations

BACKGROUND

The objective of the study was to investigate the possibility of the effect of seasonal temperature on the incidence of lethal congenital malformations in a retrospective study.

METHODS

At the National Institute of Perinatology in Mexico City, perinatal deaths due to congenital malformations were compared with the the remainder of perinatal deaths over a period of 3 years in relation to the average temperature of the months in which the fifth week of gestation occurred.

RESULTS

The division between the average temperature of the individual months was 18 degrees C, as there were no months with an average between 17.9 and 18.8 degrees C. An average of 0.86 perinatal deaths with lethal malformations had spent their embryonic life in a cold month, whereas an average of 1.54 had spent their embryonic life in a hot month; in contrast, an average of 10.24 perinatal deaths with lethal malformations had spent their embryonic life in a cold month, and a smaller number (9.23) in a hot month.

CONCLUSIONS

The perinatal deaths with lethal malformations therefore showed a significant tendency to have spent their embryonic lives during the hotter months in comparison with the other perinatal fetal deaths (p = 0.04). Further studies should be made with larger numbers of cases, maintaining careful attention to early perinatal data and local temperatures.