Researchers develop tools to make more complex biological machines from yeast.

Scientists are one step closer to making more complex microscopic biological machines, following improvements in the way that they can “re-wire” DNA in yeast, according to research published today in the journal PLoS ONE.


The researchers, from Imperial College London, have demonstrated a way of creating a new type of biological “wire”, using proteins that interact with DNA and behave like wires in electronic circuitry. The scientists say the advantage of their new biological wire is that it can be re-engineered over and over again to create potentially billions of connections between DNA components. Previously, scientists have had a limited number of “wires” available with which to link DNA components in biological machines, restricting the complexity that could be achieved.

The team has also developed more of the fundamental DNA components, called “promoters”, which are needed for re-programming yeast to perform different tasks. Scientists currently have a very limited catalogue of components from which to engineer biological machines. By enlarging the components pool and making it freely available to the scientific community via rapid Open Access publication, the team in today’s study aims to spur on development in the field of synthetic biology.

Future applications of this work could include tiny yeast-based machines that can be dropped into water supplies to detect contaminants, and yeast that records environmental conditions during the manufacture of biofuels to determine if improvements can be made to the production process.

Dr Tom Ellis, senior author of the paper from the Centre for Synthetic Biology and Innovation and the Department of Bioengineering at Imperial College London, says: “From viticulture to making bread, humans have been working with yeast for thousands of years to enhance society. Excitingly, our work is taking us closer to developing more complex biological machines with yeast. These tiny biological machines could help to improve things such as pollution monitoring and cleaner fuels, which could make a difference in all our lives.”


Dr Benjamin Blount, first author of the paper from the Centre for Synthetic Biology and Innovation and the Department of Bioengineering at Imperial College London, says: “Our new approach to re-wiring yeast opens the door to an exciting array of more complex biological devices, including cells engineered to carry out tasks similar to computers.”

In the study, the Imperial researchers modified a protein-based technology called TAL Effectors, which produce TALOR proteins, with similar qualities to wires in electronic devices. These TALORS can be easily re-engineered, which means that they can connect with many DNA-based components without causing a short circuit in the device.

The team says their research now provides biological engineers working in yeast with a valuable new toolbox.

Professor Richard Kitney, Co-Director of the Centre for Synthetic Biology and Innovation at the College, adds: “The work by Dr Ellis and the team at the Centre really takes us closer to developing much more complex biological machines with yeast, which may help to usher in a new age where biological machines could help to improve our health, the way we work, play and live.”

Professor Paul Freemont, Co-Director of the Centre for Synthetic Biology and Innovation at the College, concludes: “One of the core aims of the Centre is to provide tools and resources to the wider scientific community by sharing our research. Dr Ellis’s team has now begun to assemble characterised biological parts for yeast that will be available to researchers both in academia and industry.”






Archaeologist uses computers and satellite images to search for early human settlements.

A Harvard archaeologist has dramatically simplified the process of finding early human settlements by using computers to scour satellite images for the tell-tale clues of human habitation, and in the process uncovered thousands of new sites that might reveal clues to the earliest complex human societies.


As described in a paper published March 19 in the Proceedings of the National Academy of Sciences, Jason Ur, the John L. Loeb Associate Professor of the Social Sciences, worked with Bjoern Menze, a research affiliate in MIT’s Computer Science and Artificial Intelligence Laboratory to develop a system that identified settlements based on a series of factors – including soil discolorations and the distinctive mounding that results from the collapse of mud-brick settlements.

Armed with that profile, Ur used a computer to examine satellite images of a 23,000 square-kilometer area of north-eastern Syria, and turned up approximately 9,000 possible settlements, an increase of “at least an order of magnitude” over what had previously been identified.

“I could do this on the ground,” Ur said, of the results of the computer-aided survey. “But it would probably take me the rest of my life to survey an area this size. With these computer science techniques, however, we can immediately come up with an enormous map which is methodologically very interesting, but which also shows the staggering amount of human occupation over the last 7,000 or 8,000 years.

“What’s more, anyone who comes back to this area for any future survey would already know where to go,” he continued. “There’s no need to do this sort of initial reconnaissance to find sites. This allows you to do targeted work, so it maximizes the time we have on the ground.”

Moderate exercise lowered genetic predisposition to obesity.

Those who walked briskly for at least 1 hour per day attenuated their genetic predisposition to obesity, according to results of a study presented at the American Heart Association’s Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism 2012 Scientific Sessions.

In contrast, those who followed a sedentary lifestyle that included prolonged TV watching accentuated their genetic disposition to obesity and increased BMI, researchers found.

The study included longitudinal data from 7,740 women who participated in the Nurses’ Health Study and 4,564 men from the Health Professionals Follow-up Study. Researchers collected data on physical activity and TV habits 2 years before assessment of BMI. Genetic predisposition score was calculated on the basis of 32 established BMI-predisposing variants. The effect of genes on obesity was measured by differences in BMI per point of the genetic predisposition score, corresponding to each BMI-increasing gene, according to a press release.

Each BMI-increasing gene was associated with a 0.13 kg/m2 increase in BMI. This effect was reduced in those with the highest level of physical activity compared with those with the lowest (0.08 kg/m2 vs. 0.15 kg/m2; P<.001). The genetic effect on BMI was more pronounced in those who spent more than 40 hours per week watching TV compared with those who watched 1 or fewer hours per week (0.34 kg/m2 vs. 0.08 kg/m2; P=.001).

One hour of brisk walking per day was associated with a 0.06 kg/m2 reduction in the genetic effect on BMI. Each 2-hour per day increment in TV watching was associated with a 0.03 kg/m2 increase in genetic effect on BMI, according to the results.

For this study, obesity was defined as a BMI of at least 30.

“Our data suggest that both increasing exercise levels and reducing sedentary behaviors, especially TV watching, independently may mitigate the genetic predisposition to increased BMI,” Qibin Qi, PhD, postdoctoral research fellow in the department of nutrition at Harvard School of Public Health, and colleagues concluded.

How the function of these genes affect BMI is not clear, according to Qi.

“These genes were just identified in the past 5 years and the exact functions of the genetic variants are still unknown,” he said in a press release. “Future studies will be needed to uncover the underlying mechanisms.”

It is reasonable to assume that people who are going to be more physically active are going to be less obese. Certainly, we are learning a lot more about the negative impacts of sedentary behavior, and are using TV time as a reasonable correlate of sedentary behavior. The take-home message is that there are genes that predict propensity for obesity, but, in the case of obesity, genes are not destiny. Essentially, physical activity behavior can play an important role in the majority of patients to help them stay at an ideal body weight despite having gene profiles that are predisposed to become obese. It emphasizes the very importance of physical activity lifestyle and avoiding obesity.

Richard A. Stein, MD
Professor of Medicine
New York University


Source:Endocrine Today.




Sleep deprivation may increase caloric intake.

Results of a recent study demonstrate that lack of sleep is associated with increased caloric intake, but no change in energy expenditure.

The small study included 17 participants aged 18 to 40 years. Participants completed 1 week of home actigraphy and a 3-night acclimation phase before random assignment to sleep deprivation, defined as two-thirds of participants’ normal sleep time (n=8), or a control group, for which participants slept as they normally would (n=9). Researchers collected blood samples, calculated caloric intake and assessed energy expenditure throughout the study period.

Participants ate as much as they wanted during the study. Sleep duration during the acclimation period averaged 6.5 hours, but decreased to 5.2 hours per day in the sleep-deprived group. The sleep-deprived group consumed an average of 549 additional calories per day compared with 143 fewer calories per day in the control group (P<.01). Activity energy expenditure did not change in either group during the study (1.2% vs. 8.4%; P=.68). Results showed an increase in leptin (8.4% vs. -9.8%; P=.12) and a decrease in ghrelin (-4.9% vs. 4.6%; P=.38) in the sleep-deprived group. The researchers said changes in leptin and ghrelin may be a consequence rather than a cause of overeating.

The data were presented at the American Heart Association’s Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism 2012 Scientific Sessions.

“Sleep deprivation is a growing problem, with 28% of adults now reporting that they get 6 or fewer hours of sleep per night,” study researcher Andrew D. Calvin, MD, MPH, cardiology fellow and assistant professor of medicine at the Mayo Clinic, Rochester, Minn., said in a press release. “Larger studies of people in their home environments would help confirm our findings.”


This is a small study conducted in a tightly controlled setting where researchers monitored sleep, food intake and energy expenditure. It is extremely well done in that regard, but fairly small to make inferences to the larger population. It does provide some interesting findings, specifically that when patients are sleep-deprived, which was about 1 hour and 20 minutes less sleep a night, they increased their caloric intake by more than 500 calories a day. What this tells me is if patients are sleep-deprived they are more likely to eat more because of the sleep deprivation. Physicians should be aware of the link between sleep deprivation and obesity. Any kind of dieting or physical activity regimen a patient goes on to lose weight may be even harder to adhere to if they are sleep-deprived.

– Donna Arnett, PhD
President-Elect, American Heart Association;
Professor and Chair of Epidemiology,
University of Alabama-Birmingham

Source:Endocrine Today.


Metformin prevented plaque progression in HIV/metabolic syndrome patients.

Treatment with metformin over 1 year prevented plaque progression in a population of HIV-infected individuals with metabolic syndrome.

“Recent data suggest increased cardiovascular events among patients with HIV, with a 75% increased rate of myocardial infarction compared with non-HIV patients,” Kathleen Fitch, NP, of Massachusetts General Hospital, said during a press conference here.

“Studies have shown that a doubling of plaque is related to a 26% increase in cardiovascular disease events. Cardiac artery calcification is increased in HIV patients, but the effects of lifestyle modifications and metformin have not been evaluated in the HIV population.”

For this reason, Fitch and colleagues conducted a 12-month randomized, placebo-controlled trial to assess lifestyle modification and metformin use, alone and together, among HIV-positive individuals with metabolic syndrome. Primary outcome measure was change in coronary artery calcification score and calcified plaque volume measured by a 64-slice CT scanner. The study included 50 participants, whose fasting lipids, insulin and cardiorespiratory fitness were assessed.

The researchers found that participants who received metformin had significantly less progression of coronary artery calcification during the 12 month period: -1 ± 2 vs. 33 ± 17 (P=.004). They also had less progression in calcified plaque volume: -0.4 ± 1.9 vs. 27.6 ± 13.8 mm3 (P=.008).

Participants who were randomly assigned to lifestyle modifications showed improvement in HDL and cardiorespiratory fitness, but lifestyle modifications showed no significant effect on coronary artery calcification.

“Our results demonstrate that metformin had an effect on plaque progression in patients with HIV and metabolic syndrome,” Fitch said. “Importantly, these data also highlight a 50% rate of plaque progression in the non-treatment group, suggesting a very high rate in the natural history of plaque progression in these patients. In contrast, studies done in the general population regarding plaque progression show that plaque progresses at about half of this rate.”

Source:Endocrine Today.



Germline AIP mutations uncommon in patients with sporadic pituitary adenomas.

Aryl-hydrocarbon receptor interacting protein genetic testing should be limited to patients younger than age 40 years who are diagnosed with apparently sporadic large pituitary adenomas, according to study findings published in The Journal of Clinical Endocrinology & Metabolism.

Germline mutations of the aryl-hydrocarbon receptor interacting protein (AIP) gene are associated with a predisposition to pituitary adenomas, according to background information in the study. About half of patients with familial acromegaly demonstrate AIP mutations.

Researchers studied the prevalence of germline AIP mutations in 443 patients with pituitary adenomas of varying histotypes between June 2007 and September 2010 at Bicêtre Hospital in France. The patients had no family history of pituitary adenomas or multiple endocrine neoplasia.

The adenomas were divided into three categories — microadenomas (larger diameter <10 mm), macroadenomas (larger diameter between 10 mm and 29 mm) and giant adenomas (larger diameter = 30 mm).

Researchers screened the entire coding sequence of the AIP gene for germline mutations.

They detected AIP mutations in 16 (3.6%) of the 443 patients, including six of 148 patients (4.1%) with prolactinomas; six of 148 patients (4.1%) with acromegaly; three of 44 patients (6.8%) with corticotropic adenomas; and one of 113 patients (0.9%) with nonfunctioning adenomas. None of the six patients with thyrotropic adenomas expressed the mutation.

The patients with AIP mutation were younger at diagnosis than those without (23.6 years vs. 43.6 years, P<0.00001). Researchers detected the mutation in 7.2% (16 of 222) patients diagnosed at age younger than 40 years. They did not detect the mutation in any patients diagnosed after age 40 years.

Thirteen of the 16 patients (81.2%) found to have the mutation had either macroadenomas (n=11) or giant adenomas (n=2), and six of the 16 patients with the mutation (37.5%) had pure or mixed GH-secreting/prolactin-secreting (PRL) adenomas.

Researchers studied families of seven of the patients found to have the AIP mutation and, in each case, they discovered one asymptomatic parent carried the same mutation.

“This large prospective cohort study confirms the very low prevalence of germline AIP mutations in patients with apparently sporadic pituitary adenomas,” the researchers wrote. “We propose to limit AIP testing to patients diagnosed before age 40 with apparently sporadic large pituitary adenomas, especially GH- or PRL-secreting adenomas.”

The researchers also proposed AIP genetic testing for all children with pituitary adenomas because the mutations are found in up to one-quarter of pediatric cases.

Source:Endocrine Today.

Surgical menopause, early age at onset linked to worse physical functioning later in life.

Researchers have determined that women who elect to have surgical menopause or who experience menopause earlier in life tend to have worse physical function in older adulthood, according to results from a cross-sectional study.

“These groups of women may benefit from interventions to prevent functional decline,” the researchers said.

They evaluated 1,765 women aged 60 years or older who participated in the National Health and Nutrition Examination Survey III.

Information was obtained from the participants, such as age at final menstrual period; age at removal of the uterus and ovaries; and reported age, race and ethnicity, height, weight, educational status, smoking status, number of children and use of estrogen therapy.

Next, the participants completed a walk trial and chair rises and reported any limitations in mobility they experienced. Chair rise times were an average of 4.4% slower among those who had undergone surgical menopause vs. those who had natural menopause. As for walking speed, women with natural menopause occurring at age 55 years or older had an average walking speed of 0.05 m/second faster compared with those who underwent natural menopause at age 45 years or younger.

Functional limitation was more common in women with surgical menopause at age 55 years or older compared with women with surgical menopause at age younger than 40 years.

Source:Endocrine Today.

The Viking journey of mice and men.

House mice (Mus musculus) happily live wherever there are humans. When populations of humans migrate the mice often travel with them. New research published in BioMed Central’s open access journal BMC Evolutionary Biologyhas used evolutionary techniques on modern day and ancestral mouse mitochondrial DNA to show that the timeline of mouse colonization matches that of Viking invasion.


During the Viking age (late 8th to mid 10th century) Vikings from Norway established colonies across Scotland, the Scottish islands, Ireland, and Isle of Man. They also explored the north Atlantic, settling in the Faroe Islands, Iceland, Newfoundland and Greenland. While they intentionally took with themdomestic animals such as horses, sheep, goats and chickens they also inadvertently carried pest species, including mice.

A multinational team of researchers from the UK, USA, Iceland, Denmark and Sweden used techniques designed to characterize genetic similarity, and hence the relatedness of one population, or one individual, with another, to determine a mouse colonization timeline. Modern samples of mouse DNA were collected and compared to ancient samples dating mostly from the 10th to the 12th century. Samples of house mouse DNA were collected from nine sites in Iceland, Narsaq in Greenland, and four sites near the Viking archaeological site, L’Anse aux Meadows, in Newfoundland. The ancient samples came from the Eastern and Western settlements in Greenland and four archaeological sites in Iceland.

Analysis of mouse mitochondrial DNA showed that house mice (M. m. domesticus) hitched a lift with the Vikings, in the early 10th century, into Iceland, either from Norway or the northern part of the British Isles. From Iceland the mice continued their journey on Viking ships to settlements in Greenland. However, while descendants of these stowaways can still be found in Iceland, the early colonizers in Greenland have become extinct and their role has been filled by interloping Danish mice (M. m. musculus) brought by a second wave of European human immigrants.

Dr Eleanor Jones (affiliated with the University of York and Uppsala University) explained, “Human settlement history over the last 1000 years is reflected in the genetic sequence of mouse mitochondrial DNA. We can match the pattern of human populations to that of the house mice.” Prof Jeremy Searle, from Cornell University, continued, “Absence of traces of ancestral DNA in modern mice can be just as important. We found no evidence of house mice from the Viking period in Newfoundland. If mice did arrive in Newfoundland, then like the Vikings, their presence was fleeting and we found no genetic evidence of it.”

Source: BioMed Central.


Some orbits more popular than others in solar systems.

In young solar systems emerging around baby stars, some orbits are more popular than others, resulting in “planet pile-ups” and “planet deserts.”


Computer simulations have revealed a plausible explanation for a phenomenon that has puzzled astronomers: Rather than occupying orbits at regular distances from a star, giant gas planets similar to Jupiter and Saturn appear to prefer to occupy certain regions in mature solar systems while staying clear of others.

“Our results show that the final distribution of planets does not vary smoothly with distance from the star, but instead has clear ‘deserts’ – deficits of planets – and ‘pile-ups’ of planets at particular locations,” said Ilaria Pascucci, an assistant professor at the University of Arizona’s Lunar and Planetary Laboratory.

“Our models offer a plausible explanation for the pile-ups of giant planetsobserved recently detected in exoplanet surveys,” said Richard Alexander of the University of Leicester in the United Kingdom.

Alexander and Pascucci identified high-energy radiation from baby sun-like stars as the likely force that carves gaps in protoplanetary disks, the clouds of gas and dust that swirl around young stars and provide the raw materials for planets. The gaps then act as barricades, corralling planets into certain orbits.

The exact locations of those gaps depend on the planets’ mass, but they generally occur in an area between 1 and 2 astronomical units from the star. One astronomical unit, or AU, marks the average distance from the Earth to the sun. The findings are to be published in the journal Monthly Notices of the Royal Astronomical Society.

According to conventional wisdom, a solar system starts out from a cloud of gas and dust. At the center of the prospective solar system, material clumps together, forming a young star. As the baby star grows, its gravitational force grows as well, and it attracts dust and gas from the surrounding cloud.

Accelerated by the growing gravitation of its star, the cloud spins faster and faster, and eventually flattens into what is called a protoplanetary disk. Once the bulk of the star’s mass has formed, it is still fed material by its protoplanetary disk, but at a much lower rate.

“For a long time, it was assumed that the process of accreting material from the disk onto the star was enough to explain the thinning of the protoplanetary disk over time,” Pascucci explained. “Our new results suggest that there is another process at work that takes material out of the disk.”

Pascucci presented the findings at the 43rd Lunar and Planetary Science Conference in The Woodlands, Texas on March 19.

That process, called photo-evaporation, works by high-energy photons streaming out of the star and heating the dust and gas on the surface of the protoplanetary disk.

“The disk material that is very close to the star is very hot, but it is held in place by the star’s strong gravity,” Alexander said. “Further out in the disk where gravity is much weaker, the heated gas evaporates into space.”

Even further out in the disk, the radiation emanating from the star is not intense enough to heat the gas sufficiently to cause much evaporation. But at a distance between 1 and 2 AU, the balancing effects of gravitation and heat clear a gap, the researchers found.

While studying protoplanetary disks, Pascucci found that gas on the surface of the disk was gravitationally unbound and leaving the disk system via photoevaporation, as Alexander had previously predicted. “These were the first observations proving that photoevaporation does occur in real systems,” she said.

Encouraged by those findings, Alexander and Pascucci then used the ALICE High Performance Computing Facility at the University of Leicester to simulate protoplanetary discs undergoing accretion of material to the central star that took the effects of photo-evaporation into account.

“We don’t yet know exactly where and when planets form around youngstars, so our models considered developing solar systems with various combinations of giant planets at different locations and different stages in time,” Alexander said.

The experiments revealed that just as observations of real solar systems have shown, giant planets migrate inward before they finally settle on a stableorbit around their star. This happens because as the star draws in material from the protoplanetary disk, the planets are dragged along, like a celebrity caught in a crowd of fans.

However, the researchers discovered that once a giant planet encounters a gap cleared by photo-evaporation, it stays put.

“The planets either stop right before or behind the gap, creating a pile-up,” Pascucci said. “The local concentration of planets leaves behind regions elsewhere in the disk that are devoid of any planets. This uneven distribution is exactly what we see in many newly discovered solar systems.”

Once surveys for discovering extrasolar planet systems such as the Kepler Space Telescope project become more sensitive to outer giant planets, Alexander and Pascucci expect to find more and more evidence for the pileup of giant planets around 1 AU.

Pascucci said. “As we discover more exoplanets, we will be able to test these predictions in detail and learn more about the conditions under whichplanets form.”



Researchers develop blueprint for nuclear clock accurate over billions of years.

A clock accurate to within a tenth of a second over 14 billion years – the age of the universe – is the goal of research being reported this week by scientists from three different institutions. To be published in the journal Physical Review Letters, the research provides the blueprint for a nuclear clock that would get its extreme accuracy from the nucleus of a single thorium ion.

Such a clock could be useful for certain forms of secure communication – and perhaps of greater interest – for studying the fundamental theories of physics. A nuclear clock could be as much as one hundred times more accurate than current atomic clocks, which now serve as the basis for the global positioning system (GPS) and a broad range of important measurements.

“If you give people a better clock, they will use it,” said Alex Kuzmich, a professor in the School of Physics at the Georgia Institute of Technology and one of the paper’s co-authors. “For most applications, the atomic clocks we have are precise enough. But there are other applications where having a better clock would provide a real advantage.”

Beyond the Georgia Tech physicists, scientists in the School of Physics at the University of New South Wales in Australia and at the Department of Physics at the University of Nevada also contributed to the study. The research has been supported by the Office of Naval Research, the National Science Foundation and the Gordon Godfrey fellowship.

Early clocks used a swinging pendulum to provide the oscillations needed to track time. In modern clocks, quartz crystals provide high-frequency oscillations that act like a tuning fork, replacing the old-fashioned pendulum. Atomic clocks derive their accuracy from laser-induced oscillations of electrons in atoms. However, these electrons can be affected by magnetic and electrical fields, allowing atomic clocks to drift ever so slightly – about four seconds in the lifetime of the universe.

Because neutrons are much heavier than electrons and densely packed in the atomic nucleus, they are less susceptible to these perturbations than the electrons. A nuclear clock should therefore be less affected by environmental factors than its atomic cousin.


This image shows an RF ion trap mounted inside an ultra-high vacuum chamber at the Georgia Institute of Technology. Here, individual thorium atoms are trapped and laser-cooled to near absolute zero temperature. Credit: Alexander Radnaev

“In our paper, we show that by using lasers to orient the electrons in a very specific way, we can use the neutron of an atomic nucleus as the clock pendulum,” said Corey Campbell, a research scientist in the Kuzmich laboratory and the paper’s first author. “Because the neutron is held so tightly to the nucleus, its oscillation rate is almost completely unaffected by any external perturbations.”


To create the oscillations, the researchers plan to use a laser operating at petahertz frequencies — 10 (15) oscillations per second — to boost the nucleus of a thorium 229 ion into a higher energy state. Tuning a laser to create these higher energy states would allow scientists to set its frequency very precisely, and that frequency would be used to keep time instead of the tick of a clock or the swing of a pendulum.

The nuclear clock ion will need to be maintained at a very low temperature – tens of microkelvins – to keep it still. To produce and maintain such temperatures, physicists normally use laser cooling. But for this system, that would pose a problem because laser light is also used to create the timekeeping oscillations.

To solve that problem, the researchers include a single thorium 232 ion with the thorium 229 ion that will be used for time-keeping. The heavier ion is affected by a different wavelength than the thorium 229. The researchers then cooled the heavier ion, which also lowered the temperature of the clock ion without affecting the oscillations.

“The cooling ion acts as a refrigerator, keeping the clock ion very still,” said Alexander Radnaev, a graduate research assistant in the Kuzmich lab. “This is necessary to interrogate this clock ion for very long and to make a very accurate clock that will provide the next level of performance.”

Calculations suggest that a nuclear clock could be accurate to 10-19, compared to 10-17 for the best atomic clock.

Because they operate in slightly different ways, atomic clocks and nuclear clocks could one day be used together to examine differences in physical constants. “Some laws of physics may not be constant in time,” Kuzmich said. “Developing better clocks is a good way to study this.”

Shown is a linear chain of 29 laser-cooled Th3+ atoms suspended in vacuum by an RF ion trap at the Georgia Institute of Technology. The atoms are near absolute zero temperature and repel each other via Coulomb repulsion because of their like charges. Credit: Corey Campbell

Though the research team believes it has now demonstrated the potential to make a nuclear clock – which was first proposed in 2003 – it will still be a while before they can produce a working one.

The major challenge ahead is that the exact frequency of the laser emissions needed to excite the thorium nucleus hasn’t yet been determined, despite the efforts of many different research groups.

“People have been looking for this for 30 years,” Campbell said. “It’s worse than looking for a needle in a haystack. It’s more like looking for a needle in a million haystacks.”

But Kuzmich believes that that problem will be solved, allowing physicists to move to the next-generation of phenomenally accurate timekeepers.

“Our research shows that building a nuclear clock in this way is both worthwhile and feasible,” Kuzmich said. “We now have the tools and plans needed to move forward in realizing this system.”

Source: Georgia Institute of Technology