The top three news stories of the week, as chosen by our resident students. This week’s top stories are dolphin immune systems, giant whales, and space sperm.

Article written by Federico Dona

Understanding the dolphin immune system

The increasing number of dolphin strandings and deaths along the southeastern coast of the US and elsewhere lead scientists to find a specific way to test and monitor this behaviour. Usually antibodies – a marker of proteins – are used to measure biological activity.

The problem is: there are not commercially available marine-specific antibodies for the 42-known species of dolphin around the world. For this reason, researchers from Florida Atlantic University’s Charles E. Schmidt College of Medicine, in collaboration with Georgia Aquarium, started a study to identify cross-reactive terrestrial-specific antibodies for dolphins. This is the first study to characterise dolphin immune cell subsets using this method. The goal of this study was to assess changes in immune cell populations in dolphins in the wild and the results are published in the journal BMC Veterinary Research.

Findings from this study open the possibility of dolphin health assessment by monitoring specific changes in the immune cells of wild dolphins caused by environmental contaminants or infectious agents. The goal of this is to understand the pathogenesis of diseases in dolphins and prevent further strandings.

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Happy dolphins

Mystery solved: Why whales grew to such monster sizes.

Weighing in at 200,000 kg and stretching the length of a basketball court, the blue whale is the biggest animal that has ever lived. Now, scientists have figured out why they and other whales got so huge.

“It’s a cool study,” says Jakob Vinther, an evolutionary paleobiologist at the University of Bristol in the United Kingdom. “I’m going to send it to my students.”

Researchers have argued about when these animals got so huge. For example, in 2010 Graham Slater, an evolutionary biologist currently at the University of Chicago in Illinois, argued that cetaceans—a term that includes whales and dolphins—split into different-sized groups very early in their history, perhaps 30 million years ago.

Data has shown that they become moderately large and stayed that way until about 4.5 million years ago.  The research was carried out by Slater, Pyenson, and Goldbogen at Stanford University in Palo Alto, California.

Goldbogen helped Slater and Pyenson understand how that change was important. He studied whale eating and diving, and his work indicated that the more concentrated the food, the more efficient the feeding, especially in whales with really big mouths. Furthermore, larger whales can travel faster between patches of prey.

“The study provides support for when and how the largest whales evolved,” Smith agrees. However, although the timing of the shift seems to rule out that gigantism arose as a defence against megasharks and other predators prowling oceans at the time, she says, “I think there is enough uncertainty to remain somewhat sceptical” that the defence argument is dead.

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‘Uge whale

Sperm frozen in space produce healthy mouse pups

If NASA wants to send humans to Mars, it will probably also send along an unusual provision for the interplanetary journey: sperm. A diverse supply of human sperm could ensure the genetic variety of a new colony, which is critical to a healthy population. But no one knows whether the reproductive cells could withstand the ravages of DNA-damaging radiation in space. Now, a new study shows that mouse sperm stored for more than 9 months on the International Space Station (ISS)—where radiation levels are roughly 100 times higher than on Earth—can produce healthy, fertile mouse pups.

“This work is enormously important,” says Steven Peck, a biologist and bioethicist at Brigham Young University in Provo, Utah, who was not involved in the research.

The mice reared from the experimental sperm were fertile and healthy, and there were no obvious genetic differences between the space pups and their control brethren, Wakayama and his colleagues showed. The study suggests that the DNA damage was repaired after fertilisation and that it has “no ultimate effect” on the offspring, the team writes.

That’s good news for the space pups, but also for the many human astronauts who have gone on to become parents after spending time in space. But there’s still a lot to do before astronauts start packing for Mars, the team notes.

“The most damaging radiation is found outside the Earth’s geomagnetic shielding,” far beyond the orbit of the ISS, the researchers say. “There are much higher risks in deep space.”

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Space mice

Article written by Federico Dona