- Ocean Acidification
Dissolution in the Southern Ocean
- H. Jesse Smith
The rise of atmospheric CO2 concentrations may make the surface water in large expanses of the Southern Ocean so acidic by the year 2030 that aragonite there will start to dissolve. This will make it more difficult for key species at the base of the food web, such as pteropods, to thrive there as they do now. Hauri et al. use an ensemble of Earth system models to project how Southern Ocean acidification will progress over the next century, concluding that it could affect more than 70% of the region by 2100 if CO2 emissions are not drastically reduced.
Nat. Clim. Change 10.1038/nclimate2844 (2016).
- Water Resources
Gauging vulnerability to water shortages
- Nicholas S. Wigginton
Cities are highly vulnerable to water shortages. Lack of irrigation water, which makes up the largest proportion of global water use, can have severe social and economic consequences in urban areas. Reducing this vulnerability requires understanding how water resources vary over time, both regionally and globally. Brauman et al. developed a metric based on seasonal and drought-related depletion of water resources to provide more accurate estimates of global water scarcity. Factoring in these variables into annual global water models, the number of watersheds experiencing significant depletion increased 15-fold. Because nearly 50% of large cities and over 70% of croplands fall short of their water needs at some point in the year, rebalancing their water budgets should be a top priority.
Elementa 10.12952/journal.elementa.000083 (2016).
- Cell Division
An open and closed case
- Stella M. Hurtley
One of the first recognized stages of an animal cell's entry into mitosis is the breakdown of the nuclear envelope (NE), a double-membraned structure that contains a cell's chromosomes. However, certain yeasts, including the lab workhorse Saccharomyces cerevisiae, keep their NE intact throughout mitosis; so-called closed mitosis. Makarova et al. studied two yeasts, one of which, Schizosaccharomyces japonicus, performs open mitosis, breaking down its NE during chromosome partitioning; and one of which, S. pombe, performs closed mitosis. They found that S. pombe–like mitotic regulation of a single lipid-modifying enzyme allowed S. japonicus to expand its NE and thus perform closed mitosis.
Curr. Biol. 26, 237 (2016)
- Synthetic Biology
Tuning down an overactive thyroid
- Barbara R. Jasny
Overproduction of thyroid hormone is the hallmark of Graves' disease. Therapy is limited to suppression of thyroid hormone (which shows a high relapse rate) or destruction/removal of the thyroid gland. Saxena et al., have created a synthetic gene network that can sense and respond to abnormally high thyroid hormone levels. The circuit contained a thyroid hormone-sensing receptor fused to the DNA binding domain of yeast Gal4 and reversibly induced expression of a thyroid hormone receptor antagonist. This antagonist competed with thyroid-stimulating hormone and autoantibodies that cause abnormal activity. When cells transgenic for the circuit were injected into a mouse model of Graves' disease, the regulation of thyroid hormone was improved.
Proc. Natl. Acad. Sci. U.S.A. 10.1073pnas.1514383113 (2016).
Shared knowledge as the basis of friendship
- Gilbert Chin
How do children choose potential friends? Soley and Spelke explored this question through the creation of a site where 5-year-old children could press a button signifying with which other children they wanted to be friends. The information the researchers provided to these friend-makers was whether their potential friends liked particular songs, some of which the choosing children had not even heard. The children preferred to become friends with children whose favorite songs they knew and not those whose songs they didn't know. Thus, shared knowledge can lead to friendship, even at an early age.
Cognition 148, 106 (2016).
- Water Splitting
Placing the catalyst where it's needed
- Jake Yeston
Splitting water into hydrogen and oxygen is a potentially useful means of storing the energy in sunlight. The key is to develop cost-effective devices that harvest the light and then accelerate the chemistry. Sambur et al. used super-resolution imaging techniques to delve deep into the workings of a titanium dioxide–based sample device, in order to develop an optimization framework. By studying individual nanorods, they pin-pointed the most chemically active sites, as well as those that most effectively harnessed the potential supplied by the light. This allowed them to deposit a catalyst at the sites most in need of a boost for making oxygen from the water.
Nature 10.1038/nature16534 (2016).
Hair-trigger sensitivities in the inner ear
- Pamela J. Hines
Hair cells of the mammalian ear respond to sound to initiate signals in the auditory pathway. As the pathway is assembled during early development, before hearing, the inner hair cells produce spontaneous spikes of Ca++ signaling. Young synapses between the inner hair cells and the spiral ganglion neurons, which produce action potentials, respond with hair-trigger sensitivity. Zhang-Hooks et al. show that N-methyl-d-aspartate receptors underlie these early hypersensitive responses. Even neighboring neurons are triggered, which serves to promote survival and coordinated responses as the hearing pathway is wired up.
Neuron 10.1016/j.neuron.2015.12.016 (2016).