City lights at night make pretty views from space, but they’re not so good for sleeping. To overcome a messed up inner clock, many urban dwellers have learned to use light-blocking curtains or eye masks. But people aren’t the only ones who have to adjust to this unnatural illumination. Blackbirds, too, are exposed to this nighttime glow, and it actually makes them mature and moult sooner.
Reproduction is a seasonal ritual for birds, hence the term mating season, and they take their cues from their environment. Light is one of the factors that impacts the initiation of sexual maturity, and being exposed to light during the night appears to throw off this natural cycle.
When the Deepwater Horizon oil rig blew in 2010, it spewed some 200 million gallons of oil into the Gulf of Mexico. In order to break up the slick, another 1.84 million gallons of dispersant was added to the mix. This one-two punch of toxic chemicals devastated coastal ecosystems [pdf], but how would such a chemical bombardment affect underwater ecosystems like coral reefs? According to a new study, the
picture is no prettier.
Researchers at the Mote Marine Laboratory in Florida tested the effects of Deepwater Horizon-type oil and the dispersant used to clean it up, Corexit® 9500int, on coral larvae in the lab to replicate what may have happened following the spill. Larvae colonize reefs by sampling a surface, sticking to it and then changing into a polyp to get growing. They do this based on chemical cues in the water. Adding oil and dispersant, it turns out, severely hinders this sensitive settlement process.
The hard-working precursor cells that produce sperm just can’t catch a break. Since men make sperm throughout their lives, these cells have to divide again and again, sending one copy of themselves off to become sperm cells each time. DNA doesn’t always copy itself perfectly, so over the years, genetic errors pile up. And now a new study has quantified just how many mutations sperm will accumulate—and pass on to any offspring—for fathers of various ages. Scientists think that these mutations may be partly to blame for the fact that children with older fathers tend to have higher rates of bipolar disorder, schizophrenia, and autism.
Coral reef at the Palmyra Atoll in the northern Pacific Ocean
It’s not a good time to be a coral. Less than a third of coral reefs have legal protection from fishing and other damaging human activity. And as climate change increases oceans’ temperature and acidity, corals are suffering from more bleaching events, when stressed corals spit out the symbiotic algae they need to survive, and weaker skeletons. By 2050, coral reefs might be a lost cause. While some researchers work to protect reefs, others are preparing for conservation to fail—by collecting frozen coral sperm.
As Michelle Nijhuis explains in a New York Times article, marine biologist Mary Hagedorn is gathering reproductive material from many corals so that even as reefs die off, researchers can work at maintaining various species’ genetic diversity and trying to ensure their survival.
Praying mantises are really preying mantises, capable predators that capture and eat smaller insects. In the case of the larger, stronger female mantises, “smaller insects” also famously includes males of the same species. To mate with a potential predator, the males have to sneak up on their ladies, and a new study suggests that they use the wind to help them out: males approached females more readily when a breeze shook the females’ perch and disguised the males’ motion.
For mantises to mate, the male must creep up to the female and leap onto her back. If he fails, he will become a meal before he has a chance to reproduce. (Even if he succeeds, the female may bite his head off during copulation—but the decapitated male body is still able to continue mating and pass on his genes. So, mission accomplished?) Reaching the female undetected is thus an important male ability, and researchers tested how wind would affect it. They placed a male Chinese mantid on a kudzu leaf, upwind from a female, and set up a fan to blow air at them. Once the male detected the female, the researchers timed how long it took him to make his move, and whether the female would detect and attack him. With the artificial wind shaking the leaf, the male tried to mate with the female more quickly than in windless conditions. Windy conditions also impaired the female’s ability to sense the male: she was less likely to attack him when the fan was on.
A pregnant tsetse fly
The tsetse fly’s claim to fame is spreading the parasite that causes sleeping sickness in Africa. This public health concern has overshadowed much weirder facts about the tsetse, like the fact it gives birth to live, crawling larva—one at a time. (Sound familiar to you, mammal?) They also make “milk” to feed those larvae in utero, which uses some of same enzymes as mammals, according to new study published in the journal Biology of Reproduction. In fact, the sleeping sickness parasite is not even the most interesting organism living inside tsetse flies; no, that distinction would below to a bacterium called Wigglesworthia, without which females are sterile.
It’s time to take a journey through tsetse fly reproduction.
Insects are generally negligent parents: a female lays dozens or hundreds of eggs and flies off, leaving the young to fend for themselves. Most will die but a few will survive to lay hundreds more eggs and keep playing the numbers game. Tsetse flies, not unlike mammals, have taken the opposite tack, investing a whole lot of energy in each offspring. She keeps her eggs and larvae in the safest place possible for the longest time: inside her uterus. That’s the evolutionary explanation for live birth.
What’s the News: Researchers at Kyoto University in Japan have created fully functioning sperm from mouse embryonic stem cells. The sperm cells were able to fertilize mouse eggs in vitro, and when the scientists implanted the embryos into surrogate mothers, the mice gave birth to healthy offspring. The research, published in the journal Cell, may someday help treat infertility in humans.
What’s the News: What if the egg is fine and the sperm is dandy, but you still can’t seem to have a baby? Couples who are having trouble conceiving can testify to the frustration of learning that there’s no clear reason for their infertility. Now, however, scientists have found a genetic mutation that makes outwardly normal sperm much less fertile, potentially explaining many such cases and suggesting new routes to conception.
What’s the News: For the first time in medical history, scientists have successfully grown mouse sperm in a laboratory. As Northwestern University cell biologist Erwin Goldberg told New Scientist, “People have been trying to do this for years.” It’s hoped that being able to grow sperm outside the testes will lead to improved fertility treatments for men.
How the Heck:
Not So Fast:
Next Up: This technique still needs to be proved in humans, and if it is, it could have wide-ranging effects. For example, in the future, doctors might be able to extract testicular tissue from young boys—who haven’t yet developed mature sperm—and then grow sperm in the lab. Or for infertile men, doctors could extract germ cells, produce sperm, and then find out what’s wrong with them.
Reference: “In vitro production of functional sperm in cultured neonatal mouse testes” Takuya Sato et al. doi:10.1038/nature09850
Image: Wikimedia Commons / Bobjgalindo