Plate Nº 85 · recorded October 10, 2026
Biology & EvolutionReported finding
Healthy Calves Born Without 'Essential' Pregnancy Protein
Two healthy calves born on Feb. 26, 2026 lack interferon tau entirely, upending the long-held belief that the embryonic protein is essential for cattle pregnancy.
By Nathan Brooks3 min read586 words
In brief
- Two healthy female calves lacking interferon tau were born on February 26, 2026.
- Researchers used CRISPR-Cas9 to remove all functional IFNT gene copies and created cloned embryos.
- The study appears in Nature Communications (2026), DOI: 10.1038/s41467-026-78446-4.
- The team was led by Dr. Asghar Ali and professor Eckhard Wolf at LMU Munich.
- Prostaglandin E2 is one candidate for the alternative pregnancy signal, but its role remains unconfirmed.
Two healthy female calves born on February 26, 2026 carry no functional copies of interferon tau, a protein that textbooks have treated as indispensable for pregnancy in cattle for decades. Researchers at LMU Munich produced the animals with CRISPR-Cas9 gene editing, and the embryos lacking the protein still established pregnancies and developed to term.
The team published its results in the journal Nature Communications. The findings overturn a long-standing model of how a cattle embryo tells its mother it exists — and hint that scientists have missed part of the conversation entirely.
What was interferon tau supposed to do?
For decades, reproductive biologists have believed that interferon tau, or IFNT, was the embryo's single most important signal. The very early embryo produces the protein, which travels to the mother's uterus and blocks the hormonal changes that would otherwise bring the estrous cycle back around and end the pregnancy.
In this picture, no IFNT meant no pregnancy. The new study shows that picture was wrong, at least in cattle.
"Our findings challenge a fundamental assumption in reproductive biology. We have demonstrated that cattle embryos can establish pregnancies and develop to term without producing interferon tau, a signal previously considered indispensable," said Dr. Asghar Ali, a postdoctoral researcher at LMU's Gene Center Munich and corresponding author of the study.
How did the researchers do it?
The team, led by Ali and professor Eckhard Wolf, chair of molecular animal breeding and biotechnology and vice dean at LMU's Faculty of Veterinary Medicine, took a direct approach:
- Used CRISPR-Cas9 gene editing to knock out all functional copies of the IFNT genes in bovine cells
- Generated cloned embryos from the modified cell nuclei
- Transferred those embryos into recipient animals
The result surprised the researchers. The embryos produced no IFNT at all, yet they developed normally through the earliest stages and successfully established pregnancies. On February 26, 2026, two healthy female calves were born, and genetic testing confirmed both lack functional IFNT genes.
So how does the embryo talk to the mother?
The researchers also examined how the maternal uterus responded to the IFNT-free embryos. The characteristic interferon-driven response was absent — but the pregnancies continued anyway. That points to alternative signaling mechanisms that can maintain the hormonal conditions pregnancy requires.
One candidate is prostaglandin E2, a signaling molecule that may help preserve the corpus luteum, the ovarian structure sometimes called the "yellow body" that produces progesterone, the hormone that supports pregnancy. The researchers stress, though, that its precise role remains unestablished.
"These results fundamentally change our understanding of how the embryo communicates with the mother. The next challenge is to identify the alternative signals that allow pregnancy to be established and maintained," said Wolf, who also served as a corresponding author on the study.
What are the caveats?
The study is preliminary in scope. Two calves are a small sample, and all embryos came from cloning rather than natural conception, so the results may not cover every scenario in ordinary breeding. The proposed prostaglandin E2 pathway is a hypothesis, not a demonstrated mechanism — the authors explicitly note that its role needs further work.
Still, the finding opens new avenues for investigating early pregnancy loss, a major economic and welfare challenge in cattle breeding. If researchers can identify the mechanisms that support pregnancy independently of IFNT, that knowledge could eventually contribute to improved reproductive efficiency in livestock.
For now, the two calves stand as living evidence that a signal science once called indispensable was anything but.
via Phys.org Biology (Source)
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