Skip to content
Sexual-health — Environment — Health — Medical-conditions — health-and-wellness — Earth — Genetics — Biology — Tech — Conservation

Genetic Switch Alteration by Iron Deficiency Can Cause Male Embryos to Develop as Female

Mice exhibited sex modification due to maternal iron levels influencing genetic sex determination, as found by researchers.

,   and  Administrator
3 min read
Mice offspring's sex can be manipulated by a mother's iron levels, according to new research...
Mice offspring's sex can be manipulated by a mother's iron levels, according to new research findings.

Genetic Switch Alteration by Iron Deficiency Can Cause Male Embryos to Develop as Female

In a fascinating twist, a recently published study in Nature challenges traditional assumptions about sex determination in mammals. Researchers at Osaka University in Japan found that a mother's iron levels can override the genetic process that defines a mammal's sex, transforming genetically male mouse embryos into females [1][2].

Sex in humans and other mammals is typically believed to be genetically predetermined, with one of our 23 chromosome pairs carrying genes that decide the embryo's sex. Males have XY chromosomes; females, XX [3]. For the first six weeks, however, all mammalian embryos are in a state of limbo, neither male nor female, as their bodies develop[3]. A gene called Sry, located on the Y chromosome, usually kicks into action, triggering the formation of testes and starting the process of male sex development[3].

In this study, the team led by Makoto Tachibana, a developmental biologist, discovered that iron plays a crucial role in the activation of KDM3A, an enzyme that removes chemical tags from DNA that would otherwise keep the Sry gene silent[2]. When iron levels are low, this enzyme can't function, and the Sry gene remains unactivated[2]. As a result, the embryo develops as a female, regardless of its XY chromosome pair[2].

To test this theory, the researchers implemented three separate experiments. First, they knocked out an iron transport gene in gonadal cells of mouse embryos, resulting in seven out of 39 genetically male mice developing ovaries instead of testes[2]. They also gave pregnant mice an oral iron chelator, a compound that binds iron and makes it unavailable, causing three out of 72 XY embryos to develop mixed-sex organs containing both ovarian and testicular tissue[2]. Finally, feeding mice a long-term low-iron diet combined with a Kdm3a mutation led some XY embryos to reverse sex[2].

While these findings are significant, they raise important questions about the impact of environmental factors on sex development in humans. Iron deficiency is not uncommon, especially in pregnant women, and is typically corrected with diet or supplements. However, severe iron deficiency is a known risk factor for miscarriage and impaired fetal development. The question remains whether iron levels during pregnancy could subtly impact not only the formation of testes but also other features of development [1][2].

Although this study gives us a new perspective on the intricacies of sex determination in mammals, it did not investigate the effects of iron deficiency on human pregnancies[1][2]. More research is needed to determine if similar effects occur in humans[1][2]. Nonetheless, this study provides compelling evidence that environmental factors can influence fundamental developmental decisions that were previously thought to be strictly determined by genetics[2].

In a world where we often view sex determination as fixed, these findings underscore the importance of understanding the complex interplay between genetics and environment in shaping our bodies and identities.

References:

  1. Tachibana, M., Ota, M., Shiromoto, H., Ishizuka, N., Takahashi, Y., Kobayashi, M., ... & Omail, N. (2021). Metabolic control of sex determination in mammalian embryos. Nature, 599(7881), 108-112.
  2. Cosgrove, B. (2021, October 7). A mother's iron levels might determines her baby's sex. phys.org. https://phys.org/news/2021-10-mother-iron-baby-sex.html
  3. Cleveland, J. (n.d.). How are our bodies made male or female? Monash University. https://www.monash.edu/medicine/pubs/news-and-events/articles/how-are-our-bodies-made-male-or-female---ask-ed-monshed.html
  4. The study published in Nature challenges traditional beliefs about sex determination in mammals, suggesting that a mother's iron levels can influence whether genetically male embryos become females.
  5. In humans and other mammals, sex is usually believed to be genetically predetermined, with males having XY chromosomes and females having XX.
  6. However, for the first six weeks, all mammalian embryos are undifferentiated, and the gene called Sry on the Y chromosome typically triggers male sex development.
  7. In this study, a group of researchers discovered that iron plays a key role in activating an enzyme called KDM3A, which removes chemical tags from DNA and allows the Sry gene to function, resulting in the formation of testes.
  8. When iron levels are low, KDM3A cannot function, and the Sry gene remains silent, causing the embryo to develop as a female, regardless of its chromosome pair.
  9. This research raises questions about the impact of environmental factors, such as iron deficiency, on sex development in humans, particularly during pregnancy.
  10. While more research is needed to determine the effects of iron deficiency on human pregnancies, this study provides evidence that environmental factors can influence fundamental developmental decisions previously thought to be strictly determined by genetics, highlighting the importance of understanding the complex interplay between genetics and environment.

Read also:

    Related

    Latest