Meconium contains a wealth of information.
- A new study finds that the contents of an infants' first stool, known as meconium, can predict if they'll develop allergies with a high degree of accuracy.
- A metabolically diverse meconium, which indicates the initial food source for the gut microbiota, is associated with fewer allergies.
- The research hints at possible early interventions to prevent or treat allergies just after birth.
The prevalence of allergies arising in childhood has increased over the last 50 years, with 30 percent of the human population now having some kind of atopic disease such as eczema, food allergies, or asthma. The cause of this increase is still subject to debate, though it has been associated with a number of factors, including changes to the gut microbiomes of infants.
A new study by Canadian researchers published in Cell Reports Medicine may shed further light on how these allergies develop in children by examining the contents of their first diaper.
The things you do for science
The research team examined the first stool of 100 infants from the CHILD Cohort Study. The first stool of an infant is a thick, green, horrid-looking substance called meconium. It consists of various things that the infant ingests during the second half of gestation. Additionally, it provides not only a snapshot of what the infant was exposed to during that time, but it also reveals what the food sources will be for the initial gut bacteria that colonize the baby's digestive tract.
The content of the meconium was examined and found to contain such varied elements as amino acids, lipids, carbohydrates, and myriad other substances.
A graph of the comparative, summed abundance of different elements in a metabolic pathway after scaling to median abundance of each metabolite. The blue figures are those children without atopy, the yellow ones show the data for those with an atopic condition. Petersen et al.
The authors fed this information into an algorithm that used this data, along with the identities of the bacteria present as well as the baby's overall health, to predict which infants would go on to develop allergies within one year. The algorithm got it right 76 percent of the time.
A way to prevent childhood allergies?
Infants whose meconium had a less diverse metabolic niche the initial microbes to settle in the gut were at the highest risk of developing allergies a year later. Many of these elements were associated with the presence or absence of different bacterial groups in the digestive system of the child, which play an increasingly appreciated role in our overall health and development. The findings were summarized by senior co-author Dr. Brett Finlay:
"Our analysis revealed that newborns who developed allergic sensitization by one year of age had significantly less 'rich' meconium at birth, compared to those who didn't develop allergic sensitization."
The findings could be used to help understand how allergies form and even how to prevent them. Co-author Dr. Stuart Turvey commented on this possibility:
"We know that children with allergies are at the highest risk of also developing asthma. Now we have an opportunity to identify at-risk infants who could benefit from early interventions before they even begin to show signs and symptoms of allergies or asthma later in life."
A model for early childhood allergies
Petersen et al.
As shown above, the authors constructed a model of how they believe metabolites and bacterial diversity help prevent allergies. Increased diversity of metabolic products in the meconium encourage the development of "healthy" families of bacteria, like Peptostreptococcaceae, which in turn promote the development of a healthy and diverse gut microbiome. Ultimately, such diversity decreases the likelihood that a child will develop allergies.
Three lines of evidence point to the idea of complex, multicellular alien life being a wild goose chase. But are we clever enough to know?
- Everyone wants to know if there is alien life in the universe, but Earth may give us clues that if it exists it may not be the civilization-building kind.
- Most of Earth's history shows life that is single-celled. That doesn't mean it was simple, though. Stunning molecular machines were being evolved by those tiny critters.
- What's in a planet's atmosphere may also determine what evolution can produce. Is there a habitable zone for complex life that's much smaller than what's allowed for microbes?
"Do you think we are alone?" That question is, without fail, one of the first things people ask me when they learn I'm an astronomer. And I get why. It's also the question I most want an answer for. But that answer may depend a lot on what kind of life the universe favors (if it favors any at all). So, the question I want to briefly touch on today is how common will it be for any life that appears on any planet in the universe to start climbing up the evolutionary ladder of complexity?On Earth, the history of life is mainly a story of single cells. Earth's origin lies some 4.5 billion years ago, and the best fossil records put the emergence of life as single-celled creatures about a billion years later. After life's first appearance, almost two billion years go by during which all evolutionary activity was on those single-celled organisms. There was some really amazing biochemical machinery evolving within those little cells but if you are interested in multicellular creatures, they don't appear until sometime around 700 million years ago.
... if there is one thing we know is true, it's that nature is more clever than we are. That means it may know lots of ways to produce animals without oxygen around or even in the presence of buckets of CO2.
What are we to make of this incredibly long run of Earth as Planet Bacteria? (Note, there were actually other kinds of single-celled creatures too). Well, it certainly tells us that evolutionary success does not demand multicellularity. During these long eons, life invented the most amazing array of nano-machines for a jaw-dropping variety of purposes. For example, single-celled critters invented photosynthesis for turning sunlight into sugars, metabolisms for turning sugars into energy, and complex intracellular transport mechanisms to move stuff where it was needed and get rid of waste. Earth before plants and animals was already a fertile place full of life that had, in its way, become spectacularly complex at least on the level of biochemistry.
Given the long run of this version of Earth, it may be that there is no reason that more complex life should be expected to form in all or even most cases on other planets.
Protozoa—a term for a group of single-celled eukaryotes—and green algae in wastewater, viewed under the microscope.
Credit: sinhyu via Adobe Stock
Another way the story of life on Earth might not get repeated elsewhere in the cosmos relates to the composition of planetary atmospheres. Our world did not begin with its oxygen-rich air. Instead, oxygen didn't show up until almost two billion years after the planet formed and one billion years after life appeared. Earth's original atmosphere was, most likely, a mix of nitrogen and CO2. Remarkably it was life that pumped the oxygen into the air as a byproduct of a novel form of photosynthesis invented by a novel kind of single-celled organism, the nucleus-bearing eukaryotes. The appearance of oxygen in Earth's air was not just a curiosity for evolution. Life soon figured out how to use the newly abundant element and, it turns out, oxygen-based biochemistry was supercharged compared to what came before. With more energy available, evolution could build ever larger and more complex critters.
Oxygen may also be unique in allowing the kinds of metabolisms in multicellular life (especially ours) needed for making fast and fast-thinking animals. Astrobiologist David Catling has argued that only oxygen has the right kind of chemistry that would allow for animals to form on any world.
Atmospheres may play another role in what can and can't happen in the evolution of life. In 1959, Su-Shu Huang proposed that each star would be surrounded by a "habitable zone" of orbits where a planet would have temperatures neither too hot nor too cold to keep life from forming (i.e. liquid water could exist on the planet's surface). Since then, the habitable zone has become a staple of astrobiological studies. Astronomers now know that the outer part of the habitable zone will be dominated by worlds with lots of greenhouse gases like CO2. A planet in a location like Mars, for example, would require a thick CO2 blanket to keep its surface above freezing. But all that CO2 could present its own problems for life. Almost all forms of animal life on Earth, including sea creatures, die when placed in CO2-rich environments. This has led astronomer Eddie Schwieterman and colleagues to propose a habitable zone for complex life: A band of orbits where planets can stay warm without requiring heavy CO2 atmospheres. According to Schwieterman, animal life of the kind we know would only be able to form in this much thinner band of orbits.
So, we have three lines of evidence that may suggest multicellular life (including thinking animals) may not be the road most taken across the universe. If this were true, then the galaxy might be awash with life but be sparse in terms of tentacles, paws, or boots on the ground.
Now, before your shoulders sag in sadness, it's important to note some facts. First, there are likely 400 billion planets in our galaxy alone. This provides a lot of leeway for experimentation. Second, if there is one thing we know is true, it's that nature is more clever than we are. That means it may know lots of ways to produce animals without oxygen around or even in the presence of buckets of CO2.
We just won't know until we start looking. And here is the good news. We finally are ready to start looking.
A new study finds that dogs fed fresh human-grade food don't need to eat—or do their business—as much.
- Most dogs eat a diet that's primarily kibble.
- When fed a fresh-food diet, however, they don't need to consume as much.
- Dogs on fresh-food diets have healthier gut biomes.
You know the drill. You're having dinner when suddenly a black nose appears under the table between your legs. You tilt back and there are those eyes. Those eyes. If you're a savvy dog owner, you resist sliding down there — eating from the table is a bad habit you don't want to encourage. Plus, this is your food. It's people food. We don't eat animal food. Dogs have their own food, specially formulated for their dietary needs. Right?
Well, maybe not. A new study from researchers at the University of Illinois (U of I) finds that not only is human-grade food digestible for dogs, but it's actually more digestible than much dog food. The proof is in the pooing.
The study is an accepted manuscript for the peer-reviewed Oxford Academic Journal of Animal Science.
Four diets were tested
Credit: AntonioDiaz/Adobe Stock
The researchers tested refrigerated and fresh human-grade foods against kibble, the food most dogs live on. The ingredients of kibble are mashed into a dough and then extruded, forced through a die of some kind into the desired shape — think a pasta maker. The resulting pellets are sprayed with additional flavor and color.
For four weeks, researchers fed 12 beagles one of four diets:
- a extruded diet — Blue Buffalo Chicken and Brown Rice Recipe
- a fresh refrigerated diet — Freshpet Roasted Meals Tender Chicken Recipe
- a fresh diet — JustFoodforDogs Beef & Russet Potato Recipe
- another fresh diet — JustFoodforDogs Chicken & White Rice Recipe.
The two fresh diets contained minimally processed beef, chicken, broccoli, rice, carrots, and various food chunks in a canine casserole of sorts.
(One can't help but think how hard it would be to get finicky cats to test new diets. As if.)
Senior author Kelly S. Swanson of U of I's Department of Animal Sciences and the Division of Nutritional Sciences, was a bit surprised at how much better dogs did on people food than even refrigerated dog chow. "Based on past research we've conducted I'm not surprised with the results when feeding human-grade compared to an extruded dry diet," he says, adding, "However, I did not expect to see how well the human-grade fresh food performed, even compared to a fresh commercial processed brand."
Tracking the effect of each diet
Credit: Patryk Kosmider/Adobe Stock
The researchers tracked the dogs' weights and analyzed the microbiota in their fecal matter.
It turned out that the dogs on kibble had to eat more to maintain their body weight. This resulted in their producing 1.5 to 2.9 times the amount of poop produced by dogs on the fresh diets.
Says Swanson, "This is consistent with a 2019 National Institute of Health study in humans that found people eating a fresh whole food diet consumed on average 500 less calories per day, and reported being more satisfied, than people eating a more processed diet."
Maybe even more interesting was the effect of fresh food on the gut biome. Though there remains much we don't yet know about microbiota, it was nonetheless the case that the microbial communities found in fresh-food poo was different.
"Because a healthy gut means a healthy mutt," says Swanson, "fecal microbial and metabolite profiles are important readouts of diet assessment. As we have shown in previous studies, the fecal microbial communities of healthy dogs fed fresh diets were different than those fed kibble. These unique microbial profiles were likely due to differences in diet processing, ingredient source, and the concentration and type of dietary fibers, proteins, and fats that are known to influence what is digested by the dog and what reaches the colon for fermentation."
How did kibble take over canine diets?
Historically, dogs ate scraps left over by humans. It has only been since 1870, with the arrival of the luxe Spratt's Meat Fibrine Dog Cakes—made from "the dried unsalted gelatinous parts of Prairie Beef", mmm—that commercial dog food began to take hold. Dog bone-shaped biscuits first appeared in 1907. Ken-L Ration dates from 1922. Kibble was first extruded in 1956. Pet food had become a great way to turn human-food waste into profit.
Commercial dog food became the norm for most household canines only after a massive marketing campaign led by a group of dog-food industry lobbyists called the Pet Food Institute in 1964. Over time, for most households, dog food was what dogs ate — what else? Human food? These days more than half of U.S. dogs are overweight or obese, and certainly their diet is a factor.
We're not so special among animals after all. If something's healthy for us to eat—we're not looking at you, chocolate—maybe we should remember to share with our canine compatriots. Not from the table, though.
How do these little beasties detect light anyway?
When it comes to senses like ours, tiny single-celled organisms floating in the ocean don't have much going on. And yet, as Sacha Coesel, the lead author of a new study from University of Washington researchers, puts it: "If you look in the ocean environment, all these different organisms have this day-night cycle. They are very in tune with each other, even as they get moved around. How do they know when it's day? How do they know when it's night?"
The answer, according to Coesel and her colleagues, is four previously unknown groups of photoreceptors that may help these organisms detect day, night, and each other.
Light and dark are vital to these organisms. When the sun is up, they become energized and grow. Cell division occurs at night when the darkness' ultraviolet wavelengths are less damaging to their DNA.
"Daylight is important for ocean organisms," says senior author Virginia Armbrust, "we know that, we take it for granted. But to see the rhythm of genetic activity during these four days, and the beautiful synchronicity, you realize just how powerful light is."
Photoreceptors and optogenetics
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This combination of optical technologies and genetics is giving researchers new insights into the workings of the brain, allowing them to, for example, turn on and off single neurons as they explore the brain's myriad pathways and interactions. Optogenetics also holds promise for better management of pain, and has cast new light on brain motor decision-making.
These new-found, naturally occurring photoreceptors may substitute for, or complement, human-made photoreceptors currently used in optogenetics. It's hoped that these newcomers will prove more sensitive and better equipped to respond to particular light wavelengths. Possibly because water filters out red light—the reason the ocean looks blue—the new photoreceptors are sensitive to blue and green wavelengths of light.
"This work dramatically expanded the number of photoreceptors — the different kinds of those on-off switches — that we know of," offers Armbrust.
Finding the new photoreceptors
Credit: Dror Shitrit/Simons Collaboration on Ocean Processes and Ecology/University of Washington
The researchers identified the previously undiscovered groups of photoreceptors by analyzing RNA they'd filtered from seawater samples taken far from shore. The samples were collected every four hours over the course of four days from the Northern Pacific Ocean near Hawaii. One set of samples was collected from currents running about 15 meters beneath the surface. A second set sampled deeper down, gathering water from between 120 and 150 meters, in the "twilight zone" where organisms get by with little sunlight.
Filtering the samples produced protists—single-celled organisms with a nucleus—measuring from 200 nanometers to one tenth of a millimeter across. Among these were light-activated algae as well as simple plankton that derive their energy from the organisms they consume.
Under-appreciated, tiny drivers of sea health
The new photoreceptors help fill in at least one of the blanks in our knowledge of the countless floating communities of microscopic creatures in our seas, communities that have a far greater impact on our planet than many people realize.
Says Coesel, "Just like rainforests generate oxygen and take up carbon dioxide, ocean organisms do the same thing in the world's oceans. People probably don't realize this, but these unicellular organisms are about as important as rainforests for our planet's functioning."
A new study suggests that maintaining gut health to avoid diabetes may be little simpler than previously believed.
- Four out of trillions of gut microbes have been identified as being especially important for health.
- The microbes may play a role in obesity that can result in type 2 diabetes.
- Understanding the microbes' roles may lead to new probiotics for preventing and treating type 2 diabetes.
There are about a thousand different bacterial species living in the human gut, a population of about 10 trillion individual microbial cells. Ideally, together they help us maintain our health, but things don't always work out that way. According to a new study from Oregon State University (OSU), four microbes in particular are especially influential when it comes to whether or not we develop type 2 diabetes. The discovery of this important microbial quartet may lead to new probiotic approaches that prevent and treat the disease.
Type 2 diabetes
The problematic Western diet
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Insulin is a hormone produced in the pancreas that regulates the level of glucose—a sugar found in many carbohydrates—by controlling its absorption into liver, fat, and skeletal muscle cells. If there's too much glucose in the blood, insulin stores away the extra sugar in the liver for later use when your blood sugar is low, or if you need a jolt of energy.
With type 2 diabetes, the body no longer responds sufficiently to insulin. As a result, in an attempt to compensate and keep blood sugar at acceptable levels, the body increases its production of insulin, and this, over time, wears out the pancreas' ability to produce the hormone. At that point, the person requires injections of supplemental insulin to maintain blood sugar levels.
The most significant risk factor for developing type 2 diabetes is being overweight, which is typically a product of insufficient exercise and diet. "Type 2 diabetes is in fact a global pandemic and the number of diagnoses is expected to keep rising over the next decade," study co-leader Andrey Morgun of OSU tells the university's Newsroom. Driving this is the rising percentage of people who are overweight. "The so-called 'western diet' — high in saturated fats and refined sugars," says Morgun, "is one of the primary factors. But gut bacteria have an important role to play in modulating the effects of diet."
Credit: Kathryn Cross/Ohio State University
The OSU study explores the microbial mechanism behind "dysbiosis," or microbiome imbalance, and its role in type 2 diabetes.
Co-author OSU's Natalia Shulzhenko says, "Some studies suggest dysbiosis is caused by complex changes resulting from interactions of hundreds of different microbes. However, our study and other studies suggest that individual members of the microbial community, altered by diet, might have a significant impact on the host."
The researchers used transkingdom network analysis, a recently developed data-driven, systems-biology methodology, to examine host-microbe interactions, looking for specific microbe species that might be involved in dysbiosis.
In fact, they found some. "The analysis pointed to specific microbes that potentially would affect the way a person metabolizes glucose and lipids," explains Morgun. "Even more importantly, it allowed us to make inferences about whether those effects are harmful or beneficial to the host. And we found links between those microbes and obesity." The first step was identifying four groups of closely related species, or operational taxonomical units (OTUs), that appeared to be associated with glucose management, and that may play a role in obesity as a precursor of type 2 diabetes.
The OTUs pointed to four microbial species in particular: Lactobacillus johnsonii, Lactobacillus gasseri, Romboutsia ilealis, and Ruminococcus gnavus. As Shulzhenko explains, "The first two microbes are considered potential 'improvers' to glucose metabolism, the other two potential 'worseners.' The overall indication is that individual types of microbes and/or their interactions, and not community-level dysbiosis, are key players in type 2 diabetes." (Previous research has also associated Romboutsia ilealis, or "R. ilealis", with obesity.)
That Lactobacillus is an improver is encouraging, as it's a species often found in existing probiotic supplements, yogurts, fermented foods, and some dairy products. Shulzhenko says that in "looking at all of the metabolites, we found a few that explain a big part of probiotic effects caused by Lactobacilli treatments."
Of mice and men. And women.
Credit: Christoph Burgstedt/Adobe Stock
To confirm their suspicions, the researchers performed an experiment with mice, putting them on the mouse equivalent of the Western diet, and then feeding them improver and worsener microbe species for eight weeks.
Mice that were fed the two Lactobacilli improvers proved healthier in two ways. Their liver health—specifically, the efficiency with which they metabolized lipids and glucose—was improved, and they wound up with a lower fat mass index rating.
Comparing the results of their mice experiment with data from previous research on humans, the pattern held. The presence of more improver microbes was correlated with a lower BMI, and a stronger presence of worsens was associated with a higher BMI. Says Shulzhenko, "We found R. ilealis to be present in more than 80% of obese patients, suggesting the microbe could be a prevalent pathobiont in overweight people."
The researchers hope that their findings can help lead to new prevention and treatment approaches for type 2 diabetes. Summarizes Morgun:
"Our study reveals potential probiotic strains for treatment of type 2 diabetes and obesity as well as insights into the mechanisms of their action. That means an opportunity to develop targeted therapies rather than attempting to restore 'healthy' microbiota in general."