Using a strain of Mesotaenium endlicherianum that has been kept safe in the Algal Culture Collection at Göttingen University (SAG) for over 25 years and the unique experimental set-up there, the researchers exposed Mesotaenium endlicherianum to a continuous range of different light intensities and temperatures. Janine Fürst-Jansen, researcher at the University of Göttingen, states: “Our study began by examining the limits of the alga’s resilience — to both light and temperature. We subjected it to a wide temperature range from 8 °C to 29 °C. We were intrigued when we observed the interplay between a broad temperature and light tolerance based on our in-depth physiological analysis.” How the algae respond was not only investigated on a morphological and physiological level, but also by reading the information of about 10 billion RNA snippets. The study used network analysis to investigate the shared behaviour of almost 20,000 genes simultaneously. In these shared patterns, “hub genes” that play a central role in coordinating gene expression in response to various environmental signals were identified. This approach not only offered valuable insights into how algal gene expression is regulated in response to different conditions but, combined with evolutionary analyses, how these mechanisms are common to both land plants and their algal relatives.

Professor Jan de Vries, University of Göttingen, says: “What is so unique about the study is that our network analysis can point to entire toolboxes of genetic mechanisms that were not known to operate in these algae. And when we look at these genetic toolboxes, we find that they are shared across more than 600 million years of plant and algal evolution!” As Armin Dadras, PhD student at the University of Göttingen, explains: “Our analysis allows us to identify which genes collaborate in various plants and algae. It’s like discovering which musical notes consistently harmonize in different songs. This insight helps us uncover long-term evolutionary patterns and reveals how certain essential genetic ‘notes’ have remained consistent across a wide range of plant species, much like timeless melodies that resonate across different music genres.”

This is according to new research led by Imperial College London scientists, which could lead to better patient risk assessment and ‘microbiome therapeutics’ treatments to help combat antibiotic-resistant bacteria.

Some antibiotics target specific bacteria, but some are ‘broad spectrum’, meaning they can kill a wide range of bacteria including both ‘bad’ pathogenic bacteria that cause infections and ‘good’ bacteria that live in our guts and help with digestion and other processes.

Carbapenems are broad-spectrum antibiotics that are strong but often used as a last resort, due to their negative impacts on beneficial bacteria. Some pathogenic bacteria in the class Enterobacteriaceae however are even resistant to carbapenems, including strains of E. coli. These pathogenic bacteria colonise the gut but can spread to other sites in the body, causing difficult-to-treat infections such as bloodstream infections or recurrent urinary tract infections.

Now, a new study shows how these resistant bacteria thrive after antibiotic use, allowing them to multiply in the gut, forming a ‘reservoir’ of disease-causing bacteria. The results are published in Nature Communications.

More nutrients, less impairment

To determine the effect of antibiotics, the team tested them on samples of human faeces in the lab, alongside experiments in mice and lab tests of carbapenem-resistant Enterobacteriaceae (CRE).

Bacteria in the gut, whether ‘good’ or ‘bad’, need nutrients to grow and reproduce. The experiments showed that when antibiotics killed beneficial bacteria, the pathogenic bacteria were able to take advantage of the extra nutrients available due to less competition.

The team also showed that killing beneficial bacteria reduced the level of metabolites — waste products that inhibit pathogenic bacteria from growing further. This helped the pathogenic bacteria to thrive.

First author Alexander Yip, from the Centre for Bacterial Resistance Biology in the Department of Life Sciences at Imperial, said: “Understanding how antibiotics cause carbapenem-resistant Enterobacteriaceae to grow in the intestine means that we can develop new treatments to restrict their growth in the intestine, which will lead to a reduction in these antibiotic-resistant infections.”

Microbiome therapeutics

The team are now working on ways to interfere with this process. First, they want to identify which beneficial bacteria can ‘out-compete’ pathogenic bacteria in the absence of antibiotics: which good bacteria are able to make better use of the same nutrients and produce metabolites that restrict pathogenic bacterial growth.

With this information they hope to create ‘microbiome therapeutics’. Lead researcher Dr Julie McDonald, from the Department of Life Sciences at Imperial, explained: “When a patient is taking antibiotics we could give them inhibitory metabolites to restrict the growth of resistant bacteria. After a patient has stopped taking antibiotics we could give them a mixture of beneficial gut bacteria to help their gut microbiome recover, restore depletion of nutrients, and restore production of inhibitory metabolites.

“These microbiome therapeutics could reduce the risk of patients developing invasive antibiotic resistant infections, reduce the recurrence of invasive CRE infections in chronically colonised patients, and reduce the spread of CRE to susceptible patients.”

In the short term, the researchers say their results could be used to help reduce the risk of patients harbouring reservoirs of CRE in their guts. For example, clinicians could avoid prescribing antibiotics that elevate certain nutrients and deplete certain metabolites. Doctors could also screen patient faecal samples for these nutrients and metabolites, to identify those at increased risk of CRE colonisation.

While today’s classical data signals can get amplified across a city or an ocean, quantum signals cannot. They must be repeated in intervals — that is, stopped, copied and passed on by specialized machines called quantum repeaters. Many experts believe these quantum repeaters will play a key role in future communication networks, allowing enhanced security and enabling connections between remote quantum computers.

The Princeton study, published Aug. 30 in Nature, details the basis for a new approach to building quantum repeaters. It sends telecom-ready light emitted from a single ion implanted in a crystal. The effort was many years in the making, according to Jeff Thompson, the study’s principal author. The work combined advances in photonic design and materials science.

Other leading quantum repeater designs emit light in the visible spectrum, which degrades quickly over optical fiber and must be converted before traveling long distances. The new device is based on a single rare earth ion implanted in a host crystal. And because this ion emits light at an ideal infrared wavelength, it requires no such signal conversion, which can lead to simpler and more robust networks.

The device has two parts: a calcium tungstate crystal doped with just a handful of erbium ions, and a nanoscopic piece of silicon etched into a J-shaped channel. Pulsed with a special laser, the ion emits light up through the crystal. But the silicon piece, a whisp of a semiconductor stuck onto the top of the crystal, catches and guides individual photons out into the fiber optic cable.

Ideally, this photon would be encoded with information from the ion, Thompson said. Or more specifically, from a quantum property of the ion called spin. In a quantum repeater, collecting and interfering the signals from distant nodes would create entanglement between their spins, allowing end-to-end transmission of quantum states despite losses along the way.

Thompson’s team first started working with erbium ions several years before, but first versions used different crystals that harbored too much noise. In particular, this noise caused the frequency of the emitted photons to jump around randomly in a process known as spectral diffusion. This prevented the delicate quantum interference that is necessary to operate quantum networks. To solve this problem, his lab started working with Nathalie de Leon, associate professor of electrical and computer engineering, and Robert Cava, a leading solid-state materials scientist and Princeton’s Russell Wellman Moore Professor of Chemistry, to explore new materials that could host single erbium ions with much less noise.

They winnowed the list of candidate materials from hundreds of thousands down to a few hundred, then a couple dozen, then three. Each of the three finalists took half a year to test. The first material turned out to be not quite clear enough. The second caused the erbium to have poor quantum properties. But the third, the calcium tungstate, was just right.

To demonstrate that the new material is suitable for quantum networks, the researchers built an interferometer where photons randomly pass through one of two paths: a short path that is several feet long, or a long path that is 22 miles long (made of spooled optical fiber). Photons emitted from the ion can go on the long path or the short path, and about half the time, consecutive photons take opposite paths, and arrive at the output at the same time.

When such a collision occurs, quantum interference causes the photons to leave the output in pairs if and only if they are fundamentally indistinguishable — having the same shape and frequency. Otherwise, they leave the interferometer individually. By observing a strong suppression — up to 80 percent — of individual photons at the interferometer output, the team proved conclusively that the erbium ions in the new material emit indistinguishable photons. According to Salim Ourari, a graduate student who co-led the research, that puts the signal well above the hi-fi threshold.

While this work crosses an important threshold, additional work is required to improve the storage time of quantum states in the spin of the erbium ion. The team is currently working on making more highly refined calcium tungstate, with fewer impurities that disturb the quantum spin states.