Readers learn about swimming sperm, fishing foxes and more

Against the present

In the race to fertilize an egg, the bull’s sperm swimming in circles travel more directly than sperm traveling alone; James R. Riordan reported in “Sperm in groups of outswim loners” (SN: 11/5/22, p. 14).

This sperm can’t see where you’re going, reader Donald Bruns They wondered how the cells knew the way.

The sperm and egg swim against the flow of mucus that flows through the cervix and from the vulva. That fluid flows in a thin layer on the surface of the walls of the female genital tract; Riordan he says The drag between the sperm’s head and the wall slows the sperm down and diverts the tail downstream. This makes the sperm swim in the surface, he says.

Reader Jerry Durkan It is surprising if the sperm in the group reduce their resistance by swimming closely behind each other. It is a well-known method of execution among the knights.

“Despite superficial similarities between sperm and bicycle peloton groups, researchers caution not to draw too deep a parallel.” Riordan he says “The fluid coins that act as sperm are very different from those that are the face of the knight. Sperm swim upstream, so it’s the moisture that tells them where to go and affects how they pack, unlike horsemen who prefer a route that doesn’t look at the surrounding air.

Refusal to pay

Clusters of human nerve cells, called organoid cells, which were implanted in the brainstems, flourished and induced behaviors; Laura Sanders reported in “human nerve cells and growth in the rat brain” (SN: 11/5/22, p. 6).

Reader Linda Ferrazzara asked how the researchers kept the rat brain from rejecting the human cells.

“Rejection can be a big problem in such experiments.” Sanders he says “In this case, the researchers used mice that carried a mutation that reduced their immune systems. These immunocompromised mice were less likely to reject human cells injected into their brains.

Organoids could one day help treat various human conditions. Many problems, including disposal, still need to be solved, “but the field is moving quickly.” Sanders he says A separate experiment reported last summer about rejection problems got a different way. Researchers in Tokyo grew an organoid from the healthy colon cells of a patient with colitis, a disease characterized by inflammation in the gut. The scientists implanted the organoid into the same patient, hoping it would help grow healthier colon tissue and improve the patient’s symptoms.

Seize the day

In the first, researchers film a fox fishing for baitFred Kreier reported in “Fox captures foxes, stuns investigators” (SN: 11/5/22, p. 4).

Reader Doug Miller is shared by the potential sighting of the fox’s fishy behavior. “I saw a fox with a big fish in his mouth behind the pond that was back at our house in Illinois. We didn’t see how he took it, but it looked like a freshly caught fish, and the fox looked happy!”

Editor’s note

Nov. 17 Science reviewed the study described in “Majorana fermion signals detected” (SN: 8/19/17, p. 8) on the part of “serious irregularities and discrepancies” in the analysis of raw and published data. Three of the study’s collaborators agree with the revision, but fourteen do not. Two of the coauthors did not respond, the other is now deceased.