People are having children later than ever before. The average age of new parents in the United States has increased for at least the past half century.
As animals age, our stem cells are less effective in renewing our tissues, but this is especially true for germline stem cells, which transform into sperm and eggs.
What if there were a way to stop this process?
UC Santa Barbara biologists have published a study on the ability of fruit flies to maintain their germline stem cells'' long-term health. The research, published inNature Communications, describes a process that prevents egg production in female flies. The researchers discovered that almost every step was put on hold, extending the stem cells'' viability. These findings are likely to guide future medical discoveries.
Senior authorDenise Montell, the Duggan Professor and a distinguished professor in the Department of Molecular, Cellular, and Developmental Biology, believes she is interested in prolonging stem cells'' lifespan in general and female germline stem cells in particular.
Fruit flies enter a diapause as a seasonal strategy to save energy for reproduction when success is greater: in warmer seasons of the year. Diapause can double a fly''s life and significantly prolong their reproductive period. However, they do not hibernate.
Scientists have investigated this phenomenon previously, but most of them from a behavioral perspective. Montell said that it''s whats new about this study. We''re looking at cell biology in depth, which sounded very interesting.
According to the expert in the Montell Lab, studying this process in depth can provide clues on how to reduce stem cell aging.
Female flies under stress will pause oogenesis the production of egg cells at a specific stage of egg development. This was discovered during diapause, although it went beyond just this stage. Unlike other stressful situations, such as when predators were present or protein was scarce. The recovery of reproductive capacity also improved.
If growing egg cells is like installing new software, then the stress response is like putting the download together to take care of an errand. Diapause is like abandoning the installation and restarting the process at a later point.
One of the reasons the arrest is so complete is that every phase of development was put on hold, according to Montell. For example, a germline stem cell will normally form two daughter cells. One of these continues dividing to become an egg, while the other is a stem cell, capable of repeating the process later.
In diapause, this process is frozen shortly before the daughter cells collide from each other in the stage known as cytokinesis. The conjoined cells have two distinct nuclei, but remain attached. This resolves once favorable conditions return and the fly emerges from diapause.
A concentration of DNA damage triggered P53, a genetic-damage checkpoint protein that stops a cell from replicating. Cells usually have a reasonable amount of replication potential: they can divide only once before they get tired and quit, according to Montell. P53 preserves the possibility for the cell to repair itself and resume dividing later.
Montell and Easwaran were curious if they could hack this system to prolong the longevity of germline stem cells under regular conditions. They targeted a juvenile hormone, which plays a role in egg production, and their levels were reduced during diapause.
Once the compound was reintroduced, they removed the cells that created a juvenile hormone, which ended egg production, and then reintroduced the hormone into the animals food six weeks later. They found that temporarily removing the hormone extended the flies'' reproductive potential, similar to diapause, and egg production improved.
Montell emphasised that this is just the beginning of their investigation into diapause, and that they may uncover applications in human medicine. We understand that it is possible to find things in very simple organisms that hold true in humans, according to Montell. For example, her research on cell motility in fruit flies sparked a strong connection between cancers and the body.
This process of diapause requires a National Institute on Aging grant, which the agency is very convinced that this kind of basic research in a simple animal can reveal things that are true in humans, according to the author.
Easwaran is sure that the results we provide in the paper may help reduce age-related illnesses and illnesses, he said, while aiding us to age gracefully.