The spermatogonial stem cells (SSCs) are
responsible for producing sperm. Sperm are constantly replenished in the adult male body.
Understanding the workings of stem cells responsible for this
replenishment is expected to shed light on why male fertility diminishes
with age, and possibly lead to new treatments for infertility.
"So-called Myc genes play an important role in stem cells' ability to
self-renew," explains Kyoto University's Takashi Shinohara, who is
interested specifically in SSCs. Shinohara adds that SSCs are unique,
because they are "the only stem cells that transmit genetic information
to offspring."
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Results of a new study that was presented at The Endocrine Society''s 93rd Annual Meeting in Boston reveal that daily exposure to bisphenol A causes lowered fertility in male mice.
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‘The Myc genes play an important role in stem cells' ability to self-renew. These findings could have important implications for infertility research in the future.’
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In a new report in Genes & Development, the Shinohara lab demonstrates how the Myc gene regulates the self-renewal of mouse SSCs, via a process of glycolysis control. Glycolysis is a key part of cells' energy-making mechanism.
The scientists injected two types of SSCs into mouse testes: normal
cells in some, and Myc gene-suppressed in others. Two months later, they
found that the total number of abnormal SSCs was far fewer than normal
ones. Gene analysis showed that the capacity for self-renewal had been
compromised, with possibly important implications for sperm production
in these mice.
![Study Says Environmental Exposure to Organochlorines may Affect Male Fertility]( "Study Says Environmental Exposure to Organochlorines may Affect Male Fertility")
A recent study reveals that men exposed to organochlorine chemicals in the environment are at an increased risk of sperm abnormalities.
"We found changes in the expression of genes that would slow the cell cycle," says Shinohara.
In other words, suppressed SSCs could self-renew, but at a slower than normal rate. Further study showed that this diminished rate was accompanied by impaired glycolysis, suggesting that the cells were not generating sufficient energy.
"A difference in glycolysis could explain natural differences in SSC self-renewal between mice," elaborates Mito Kanatsu-Shinohara, first-author of the paper. "DBA/2 and B6 are two mouse types in which SSCs are know to self-renew at different rates."
Further experiments confirmed that glycolysis was more active in the cells of DBA/2 mice. Moreover, isolating cells from B6 mice and treating them with certain chemicals that enhanced glycolysis could increase the proliferation rate to levels comparable with DBA/2.
"These findings could have important implications for infertility research in the future," says Shinohara. "Stimulating the metabolism of SSCs could improve their proliferation. However, more careful study of the molecular pathways is necessary."
Source: Eurekalert
Study Says Environmental Exposure to Organochlorines may Affect Male Fertility
A recent study reveals that men exposed to organochlorine chemicals in the environment are at an increased risk of sperm abnormalities.
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"We found changes in the expression of genes that would slow the cell cycle," says Shinohara.
In other words, suppressed SSCs could self-renew, but at a slower than normal rate. Further study showed that this diminished rate was accompanied by impaired glycolysis, suggesting that the cells were not generating sufficient energy.
"A difference in glycolysis could explain natural differences in SSC self-renewal between mice," elaborates Mito Kanatsu-Shinohara, first-author of the paper. "DBA/2 and B6 are two mouse types in which SSCs are know to self-renew at different rates."
Further experiments confirmed that glycolysis was more active in the cells of DBA/2 mice. Moreover, isolating cells from B6 mice and treating them with certain chemicals that enhanced glycolysis could increase the proliferation rate to levels comparable with DBA/2.
"These findings could have important implications for infertility research in the future," says Shinohara. "Stimulating the metabolism of SSCs could improve their proliferation. However, more careful study of the molecular pathways is necessary."
Source: Eurekalert
Nonhuman Primates Not Immune to Fading Female Fertility
A study of mortality and fertility patterns among seven species of wild apes and monkeys and their relatives shows that menopause sets humans apart from other primates, compared with similar data from hunter-gatherer humans.
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