Stanford University

The infertile men in the study each had a type of genetic mutation that prevented them from making mature sperm — a condition called azoospermia. The research suggests that the men with azoospermia may have had germ cells at some point in their early lives, but lost them as they matured to adulthood.

Although the researchers were able to create primordial germ cells from the infertile men, their stem cells made far fewer of these sperm progenitors than did stem cells from men without the mutations. The research provides a useful, much-needed model to study the earliest steps of human reproduction.

- See more at: http://med.stanford.edu/ism/2014/may/germ-cell.html#sthash.H2v2ps1E.dpuf

n contrast, the stem cells made from adult skin required no artificial manipulation. Once implanted into the seminiferous tubules of mice (where the animals’ sperm production takes place), they differentiated into what the scientists termed “germ-cell-like cells,” simply by virtue of the environment in which they were placed. The cells expressed many genes known to be expressed in primordial germ cells, and underwent a genetic reprogramming process called demethylation associated with sperm production. - See more at: http://med.stanford.edu/ism/2014/may/germ-cell.html#sthash.H2v2ps1E.dpuf

U.S. corn yields are increasingly vulnerable to hot, dry weather, Stanford research shows

I think it's exciting that data like this now exist to see what's actually happening in fields. By taking advantage of this data, we can learn a lot fairly quickly," he said. "Of course, our hope is to improve the situation. But these results challenge the idea that U.S. agriculture will just easily adapt to climate changes because we invest a lot and are really high-tech."

Lobell and colleagues are also looking at ways crops may perform better under increasingly hot conditions. "But I wouldn't expect any miracles," he said. "It will take targeted efforts, and even then gains could be modest. There's only so much a plant can do when it is hot and dry."

Laura Seaman is the communications and external relations manager for Stanford's Center on Food Security and the Environment, a joint program of Stanford's Freeman Spogli Institute for International Studies and the Stanford Woods Institute for the Environment.

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