Penguins Are Among the World’s Slowest-Evolving Birds: Study
“Feel-Good” Neurons Steer Mice Toward Hydration-Boosting Liquids
Phages Treat Gut Inflammation in Mice
Hummingbird that was feared extinct is spotted in Colombian mountains
Penguins Are Among the World’s Slowest-Evolving Birds: Study
The findings mean that penguins may struggle to adapt under rapid climate change, researchers say.
Catherine Offord Jul 19, 2022
Penguins are some of the slowest-evolving birds ever studied, a trait that could make them particularly vulnerable to the effects of climate change, according to a paper published today (July 19) in Nature Communications.
Researchers used genomic and fossil data to piece together the history of penguin diversification starting 60 million years ago, when the birds lost their ability to fly. The team found that although penguins have become highly specialized to thrive in their extreme environments, their evolutionary rate has decreased drastically, meaning that they may struggle to adapt to rapidly warming ocean temperatures and other effects of anthropogenic climate change.
“Modern penguins seem to be less well equipped to survive these rapid environmental changes than ancient penguins because of this decrease in evolutionary rate,” Vanesa De Pietri, an avian paleontologist at the United Kingdom’s University of Canterbury who was not involved in the work, tells National Geographic. “Have they specialized themselves into a corner? Yeah, probably.”
The study identified various ways in which penguins’ evolution has tracked geological and climatic conditions in the past. For example, many of the 18 species of penguin in the world today seem to have arisen within the last 3 million years—something that the researchers suggest was driven by climatic changes leading up to and following the last ice age.
“As ice volumes increased during the [last glacial period,] high-latitude penguin species were likely forced into isolated mid-latitude refugia,” the authors write in their paper. “As climate warmed from the late Pleistocene to Holocene, these species moved back towards the poles, recolonizing landmasses and islands as they became habitable once again, and, notably, experiencing secondary contact with one another.”
It’s not clear exactly what caused penguin evolution to decelerate to the extent that it did. While the birds’ large size and slow reproduction may play some role, “we would never have guessed that would have the slowest rate yet seen in birds,” study coauthor Daniel Ksepka of the Bruce Museum in Greenwich, Connecticut, tells the UK Natural History Museum (NHM) news site.
The researchers note that penguins’ sister group, the Procellariiformes—which includes albatrosses and other seabirds—also have low evolutionary rates compared with those of other avian orders, suggesting there might be “a gradual slowdown associated with increasingly aquatic ecology,” they write in their paper.
“It’s a topic that certainly warrants more investigation to try and discover why this occurs,” Ksepka tells NHM.
Keywords: adaptation climate change evolution evolutionary biologygenetics & genomics nutshell penguins phylogeny zoology
“Feel-Good” Neurons Steer Mice Toward Hydration-Boosting Liquids
The cells signal to the brain how hydrating particular beverages are, but it’s not yet clear whether they play a similar role in humans.
Shafaq Zia, Jul 19, 2022
Dopamine, a “feel good” chemical, is released in the brain when we eat high-fat and sugary delights that taste good. However, it may also guide our food and drink choices through a mechanism that has nothing to do with taste, a recent mouse study finds.
A team of researchers at the University of California, San Francisco (UCSF), describe the new mechanism in a paper published July 13 in Nature. They report that dopamine-releasing neurons in a region of the brain called the ventral tegmental area (VTA) that is important for reward-seeking behavior, motivation, and aversion are activated by hydration.
This mechanism, the researchers say, explains how animals learn to prefer one type of food over another in order to survive in the wild. “Many animals actually get most of their water from food,” says study coauthor James Grove, a neuroscientist at UCSF. “So they presumably have to learn through experience which foods are rehydrating and what they should eat when they’re thirsty.” To understand which neural mechanisms in the brain might associate the tastes of foods and liquids with their effects after absorption into the bloodstream, the researchers turned to mouse experiments.
Using technology that allowed them to look at the activity of individual VTA neurons in the mice, the scientists gave thirsty animals unrestricted access to water for five minutes and observed how their neural activity changed. The mice voraciously drank water, and dopamine neurons in the VTA became active as a result of this rewarding stimulus—a mechanism that was already well-established in previous research.
Keywords: Brain Brain activity Decision-making Dopamine Drinking drinking water Eating food intake Neuroscience News Obesity Physiology reward
Phages Treat Gut Inflammation in Mice
Mixtures of viruses that attack inflammatory bowel disease–causing bacteria in mice also survive the digestive tract and are well-tolerated in humans, a study finds.
Andy Carstens. Aug 4, 2022
The idea of using bacteria-infecting viruses called bacteriophages to kill specific microbes implicated in disease has been around for more than a century. But a major barrier to using phage therapies is that the microbiome is constantly evolving and using molecular strategies such as CRISPR to evade attack. Research published today (August 4) in Cell purports to have taken a step toward overcoming that hurdle by using a cocktail of phages that use multiple lines of attack against Klebsiella pneumonia bacteria, preventing them from evolving resistance to the mixture. The researchers behind the study report that their blend of phages successfully treated symptoms of inflammatory bowel diseases (IBDs) such as ulcerative colitis and Crohn’s disease in mice, and was well-tolerated in very early testing on healthy human volunteers.
“For the first time, we [were] able to develop a precision therapy that would target a group of commensals within this huge and divergent microbiome without impacting the surrounding critically important microbial ecosystem,” says study coauthor Eran Elinav, a microbiome researcher at the Weizmann Institute of Science in Israel and the German Cancer Research Center.
Elinav and his colleagues first performed genomic sequencing to characterize the bacteria in the microbiomes of 537 people with IBDs in four countries: France, Germany, Israel, and the US. The analysis revealed that Klebsiella pneumonia was one of the most common bacteria in the cohort, present in nearly 40 percent of the people across all four regions. Furthermore, this species of bacteria was more abundant in patients experiencing IBD flareups compared to those in remission, suggesting it plays an important role in disease.
While Elinav says that other bacteria such as E. coli may also contribute to IBDs, K. pneumonia’s pervasiveness throughout the cohort led the team to focus on it in their subsequent analyses. They further characterized the strains of K. pneumonia represented in stool samples from the people with IBDs, and through sequencing and computational analyses, identified a particular family, which they call the Kp2 clade, that was strongly associated with IBDs.
Keywords: bacterial evolution Bacteriophage Bacteriophages Colitis Crohn's drug development drug testing gut bacteria gut microbiome human trial inflammatory bowel disease Mice Microbiology Microbiome mouse model News Phage phage therapy Phase I Resistance study story
Hummingbird that was feared extinct is spotted in Colombian mountains
The Santa Marta sabrewing, an emerald green hummingbird, has been officially documented for only the second time since it was discovered in 1946
Life 5 August 2022 By Luke Taylor
After years of attempts to find one of the world’s 10 most wanted bird species, the Santa Marta sabrewing has been unexpectedly rediscovered deep in the mountains of Colombia.
The tiny hummingbird had only been officially spotted twice: once when it was discovered in 1946 and again in 2010 when it landed serendipitously in a researcher’s mist net. Since then, it has been presumed by many to be extinct.
“It’s so incredible to see photos and video of the Santa Marta sabrewing,” said John Mittermeier, director of threatened species outreach at the American Bird Conservancy, in a press release. “It’s like seeing a phantom.”
The lost Santa Marta sabrewing has been a magnet for bird enthusiasts desperate to make history by confirming its existence.
Many have returned home disappointed and some may have even been teased by its elusive emerald green body and shimmery blue throat, says Natalia Ocampo-Peñuela, a Colombian ornithologist at the University of California, Santa Cruz. Some birders snapped photos of what appeared to be the sabrewing’s body, but without the tail, they were inconclusive.
“They may have been misidentifying it or maybe it just has such a reduced population or specific habitat that all the birdwatchers that went out there missed it,” says Ocampo-Peñuela. “It was there hiding all along!”
The rare bird was spotted perched on a branch singing by Yurgen Vega, who was studying the area’s endemic birds with the World Parrot Trust and two conservation research organisations, SELVA and ProCAT Colombia. The unlikely sighting may just secure its survival, say experts.
Little is known about the mysterious species except that it usually lives in neotropical forest at an altitude of 1200 to 1800 metres and may migrate to chilly moors during the rainy season to search for flowering plants.
The sabrewing was added to the Search for Lost Birds top 10 most wanted list last year in the hope of saving it.
The forests of the Sierra Nevada are under threat from agriculture and the sighting was made in an unprotected area.
Understanding the sabrewing’s habits and habitat should help inform conservation efforts, say conservation advocacy groups.
The Santa Marta mountains are home to at least 22 endemic bird species and a haven of biodiversity in a country that is home to more species per square kilometre than anywhere else in the world.
The confirmation that the region is home to yet another endemic species strengthens the argument that the government must work with conservationists and local communities to preserve the bird, says Esteban Botero-Delgadillo at SELVA.
Aucun commentaire:
Enregistrer un commentaire