A new study looks at how aging affects chromosome segregation, RNA processing and mitochondrial metabolism. The results indicate that age can affect the ability of oocytes to process key gene products in the final steps of their development.
This Fertility of female Be adversely affected by age By changing the level of RNA, the function of genes involved in the key biological pathways of the final stage is then destroyed. Egg maturation.These are the conclusions of a new study published in the journal Aging cells.
The research team sequenced RNA molecules-also known as Transcriptome-Understand which genes in oocytes are affected with age.They performed single-cell sequencing to analyze 72 oocytes Individuals from 37 donors between the ages of 18 and 43.
Scientists found that with age, the number of gene transcripts involved in chromosome separation and RNA processing gradually increased, while the number of transcripts related to mitochondrial metabolism decreased.
Age affects the last step of oocyte maturation, which is the basic stage of reproduction, because it provides the material needed for the normal development and survival of a new embryo.
Changes in the transcriptome only occur when the egg reaches the final stage of its development during maturation in vitro. Therefore, in immature eggs, the transcriptome is less affected by age. Experts believe that age affects the ability of oocytes to process genetic products that are critical to the final steps of their development.
Further analysis revealed a series of possible major regulatory genes, which are affected by age. These genes are the most important genes in the regulatory system. Future research will be able to determine whether these genes play a key role in oocyte aging.
He said: “Age has an impact on the last step of oocyte maturation. Egg maturation is the basic stage of reproduction because it provides the material needed for the normal development and survival of a new embryo.” Bernhard Payer, The group leader of the Genome Regulatory Center (CRG) And co-author of the study. “What we still don’t know is which of these changes are only the result of the aging process, and which can directly cause the quality of oocytes to decline with age.”
Examples of different stages of human oocytes used in this study. On the left is the vesicular oocyte, which is an immature stage characterized by the presence of a visible nucleus (white arrow). On the right is an in vitro mature metaphase II oocyte (IVM-MII), which is equivalent to an in vivo mature egg. As a result of the maturation process, polar bodies can be detected (black arrows). Most age-related changes are observed in the second stage of oocytes. /Montserrat Barragan | Eugene Clinic
The passage of time, weight and fertility
Women’s fertility usually declines with age.One of the main reasons for this situation is due to Ovarian Reserve, Because a woman is born with all the oocytes in her life, from which the eggs mature.
another reason is Egg quality Decrease over time, which is considered to be one of the main reasons for the highest infertility rate 35 years later. Being overweight or underweight is also related to poor oocyte quality and reproductive results.
The team used information about the weight and height of the donor to assess the impact of the donor. body mass index (BMI) Transcriptome. Compared with age, abnormal BMI mainly affects the transcriptome of immature oocytes.
According to experts, this finding suggests that the decline in fertility caused by age may have a different basic mechanism from the decline in fertility caused by abnormal BMI.
Although more research is needed, these results may lead to the development of new diagnostic tools in the future to better assess the quality of oocytes used in oocytes. Reproductive medicine. The authors concluded that, in addition, they can also help potential drug treatments, modulating the affected pathways to restore aging oocytes.
Llonch S, Barragán M, Nieto P, etc. Transcriptome analysis of single human oocytes revealed different maturation-dependent pathways affected by age. Aging cells. 2021; 00: e13360. https://doi.org/10.1111/acel.13360
Funding source: EUGIN clinic; National Research Institute (AEI), grant/award number: EUR2019-103817; University of Catalonia and Research Grant Management Agency (AGAUR), grant/award number: 2017 SGR 346; European Commission, awarded /Award number: 754422; AXA Research Fund; Spanish Ministry of Science, Innovation and University, Award/Award Number: BFU2017-88407-P