Oct 12, 2017

Axios Science

By Alison Snyder
Alison Snyder

Welcome back. If you like Axios Science, please invite your friends and colleagues to sign up for the newsletter. And, as always, send me your feedback. You can reply to this email or send me a note at alison@axios.com.

Revisiting the ban on embryo research

Rice University's Kirstin Matthews writes, in an Axios piece this week: In May 2016, scientists reached a new milestone — the culturing of human embryos to 14 days after fertilization. That experiment was stopped because of current international guidelines, but some scientists would now like policymakers to reconsider this rule.

The bottom line: Given the controversial nature of this work, knowledge for its own sake may not ultimately be an adequate justification for extending human embryo research, but now is the time for further debate.

Read Kirstin's full piece.

1 important trend: Americans without kin

A new study of black and white Americans projects black individuals may have less family to lean on as they age. It also shows a continued increase in the number of Americans without living kin.

Why it matters: As we age, we tend to rely on children and spouses for help. An estimated 34.2 million Americans provided unpaid care to an adult age 50 or older in 2015, and 42% of caregivers are caring for a parent. They are, in other words, a pillar of health care in an aging America.

Key findings:

  • Rachel Margolis from the University of Western Ontario and Ashton Verdery from Penn State University project 21.1 million black and white individuals over 50 will be without a living partner or children in 2060.
  • If parents and siblings are factored in, "we estimate that there will be 6.3 million whites and blacks without a living partner, children, siblings, or parents in 2060," they wrote.
  • Biggest factors: An increase in childlessness, never marrying, and mortality — "black Americans are twice as likely to lose a child or spouse by the age of 50," says Verdery, citing recent research.
  • Limitation: There wasn't sufficient data to study other racial groups.

Read more of my piece here.

Axios stories to spark your brain
Tried and true: simulating dolphin sex

The big question: How do the genitals of marine mammals fit together? Researchers want to know whether there are various forms of genitalia that reflect different sexual behaviors and affect fertility in order to better understand the many possible functions of sex and improve animal breeding in captivity.

The problem: Marine mammals are rarely seen mating in the wild so little is known about what's happening when they have sex.

The experiment: Dalhousie University's Dara Orbach and her colleagues collected penises and vaginas from dead marine animals. They had the necessary parts to simulate sex in four species — bottlenose dolphins, short-beaked common dolphins, harbour porpoises, and harbour seals.

  • Penises were inflated by pumping air under pressure into a beer keg filled with saline solution and then into the genitalia. (Side note: Scientists used to think dolphins swam around with fully erect penises but the researchers observed "huge volume changes" once they added the fluid.)
  • Vagina molds were made by injecting them with silicone.
  • For each species, the penis was then inserted into the vagina, sewn in place, chemically fixed and soaked in iodine for two weeks to stain the tissue.
  • CT scans were taken of the casts in order to see differences in the tissue.

What they found: Certain positions lead to deeper penetration and therefore create less distance for the sperm to travel to fertilize the egg. Two of the four species studied exhibited genitalia that seemed to evolve together to ensure the best fertilization. In harbour porpoises and bottlenose dolphins, the folds and spirals between the cervix and clitoris seem to "act as a barrier to penile penetration."

Genital shape, in other words, may allow female dolphins — which males may aggressively mate with — some choice in paternity. (Something similar is seen in ducks.)

Bottom line: The study is limited to just four species and the simulated sex would need to be verified with the real deal. However, the findings suggest there may be plenty of vagina varieties in the sea, some of which support the idea that their shape reflects sexual conflict within the species.

Dive deeper: Science's David Shultz interviewed Orbach when the findings were first presented at a conference earlier this year.

What we're reading elsewhere
Something wondrous

Unlike us humans who have two sets of chromosomes (one from each parent), some plants have four, six or more complete copies of each chromosome, a genetic condition called polyploidy that, though rare, is being discovered throughout the natural world.

How it works: During reproduction, errors can cause an organism's entire genome to be duplicated. Over millions of years, some genes and their copies are lost, others are retained and rearranged — altering and shifting the different components in a genetic network. Most of the genome eventually reverts to having only two copies of a gene, typically leading to a sort of evolutionary dead-end. Polyploidy happens all the time but the vast majority of these organisms die. "The few that make it become success stories across the tree of life," Michigan State University's Patrick Edger says.

They're seen in the histories of papaya, asparagus, conifer pines and the ancestors of pumpkins and gourds. Scientists just sequenced the orchid Apostasia shenzhenica (pictured above) and uncovered a duplication event shared by all orchids that they think plays a role in the evolution of the many variations of those plants.

Whole genome duplication isn't just for plants: an event that happened in fish 320 million years ago is tied to the patterns and pigments seen in some species and our own early vertebrate ancestors may have undergone two such events.

Expanding the genome may allow organisms to respond and adapt to environmental changes — some of these events occur in clumps at roughly the same time as mass extinctions, says Edger. And, in the long run, the retention of some genes and not others may have given rise to the range of shapes and forms we see in the natural world. (That is debated, though, since non-polyploids are also diverse.)

Why it matters now: Breeding polyploid plants — like strawberries and some varieties of wheat — is difficult. Instead of having two places to look for a gene, there are four or more. Unraveling the genetics of these plants could help breeders improve crops and understand how organisms adapt to climate change. There's also evidence polyploidy plays a role in cancer by allowing tumors to rapidly evolve.

Alison Snyder