[…]

The study, published in the journal Cell, compared ‘brain organoids’ – 3-D tissues grown from stem cells which model early brain development—that were grown from human, gorilla and chimpanzee stem cells.

Similar to actual brains, the human brain organoids grew a lot larger than the organoids from other apes.

[…]

During the early stages of brain development, neurons are made by stem cells called neural progenitors. These progenitor cells initially have a cylindrical shape that makes it easy for them to split into identical daughter cells with the same shape.

The more times the neural progenitor cells multiply at this stage, the more neurons there will be later.

As the cells mature and slow their multiplication, they elongate, forming a shape like a stretched ice-cream cone.

Previously, research in mice had shown that their neural progenitor cells mature into a conical shape and slow their multiplication within hours.

Now, brain organoids have allowed researchers to uncover how this development happens in humans, gorillas and chimpanzees.

They found that in gorillas and chimpanzees this transition takes a long time, occurring over approximately five days.

Human progenitors were even more delayed in this transition, taking around seven days. The human progenitor cells maintained their cylinder-like shape for longer than other apes and during this time they split more frequently, producing more cells.

This difference in the speed of transition from neural progenitors to neurons means that the human cells have more time to multiply. This could be largely responsible for the approximately three-fold greater number of neurons in human brains compared with gorilla or chimpanzee brains.

[…]

To uncover the genetic mechanism driving these differences, the researchers compared gene expression—which genes are turned on and off—in the human brain organoids versus the other apes.

They identified differences in a gene called ‘ZEB2’, which was turned on sooner in gorilla brain organoids than in the human organoids.

To test the effects of the gene in gorilla progenitor cells, they delayed the effects of ZEB2. This slowed the maturation of the progenitor cells, making the gorilla brain organoids develop more similarly to human—slower and larger.

Conversely, turning on the ZEB2 gene sooner in human progenitor cells promoted premature transition in human organoids, so that they developed more like ape organoids.

The researchers note that organoids are a model and, like all models, do not to fully replicate real brains, especially mature brain function. But for fundamental questions about our evolution, these brain tissues in a dish provide an unprecedented view into key stages of brain development that would be impossible to study otherwise.

Dr. Lancaster was part of the team that created the first brain organoids in 2013.

Source: Scientists discover how humans develop larger brains than other apes

It’s been well established by now that the agricultural systems producing our food contribute at least one fifth of global anthropogenic carbon emissions—and up to a third if waste and transportation are factored in. A troubling new report points to a previously overlooked source: an industrial fishing process practiced by dozens of countries around the world, including the United States, China, and the E.U.

The study, published today in the scientific journal Nature, is the first to calculate the carbon cost of bottom trawling, in which fishing fleets drag immense weighted nets along the ocean floor, scraping up fish, shellfish and crustaceans along with significant portions of their habitats.

According to calculations conducted by the report’s 26 authors, bottom trawling is responsible for one gigaton of carbon emissions a year—a higher annual total than (pre-pandemic) aviation emissions. Not only does the practice contribute to climate change, it is extremely damaging to ocean biodiversity—the “equivalent of ploughing an old-growth forest into the ground, over and over and over again until there is nothing left” according to lead author Enric Sala, a marine biologist who is also National Geographic’s Explorer in Residence.

Bottom trawling is also one of the least cost effective methods of fishing. Most locations have been trawled so many times, there is little left worth catching, says Sala. “Without government subsidies, no one would be making a penny.” But Sala didn’t set out to condemn bottom trawlers when he designed the research project back in 2018. He was looking for the incentives that just might make the fishing industry, and governments, give up on the practice on their own. The carbon findings may just do the trick.

[…]

Refuting a long-held view that ocean protection harms fisheries, the study found that well placed marine protected areas (MPAs) that ban fishing would actually boost the production of marine life by functioning as fish nurseries and biodiversity generators capable of seeding stocks elsewhere. According to the study results, protecting the right places could increase the global seafood catch by over 8 million metric tons a year, despite the challenges of overfishing and climate change.

Bottom trawling, however, would have to stop, says Sala. While mangroves, kelp forests and sea grass meadows are good at capturing carbon, the bottom of the ocean, piled deep with marine animal debris, is a far greater carbon sink. But when the trawlers’ weighted nets scrape the sea floor that carbon is released back into the water. Excess carbon in water turns it acidic, which is damaging to sea life.

Worse still, the practice also impacts the ocean’s ability to absorb atmospheric carbon: if the water is already saturated from sources down below, it will be unable to absorb human-caused emissions from above, hamstringing one of our best assets in the fight against climate change. By combining publicly-available data on global bottom trawler activity with pixel-level assessments of carbon stored in the top layers of ocean sediments, Sala and his team were able to calculate the amount of emissions produced by the technique, down to the level of national fleets. The European Union, for example, releases 274,718,086 metric tons of marine sediment carbon into the ocean a year, while Chinese fleets release 769,294,185 metric tons, and the United States releases 19,373,438.

[…]

Source: Bottom Trawling for Fish Boosts Carbon Emissions, Study Says | Time

A bit of seaweed in cattle feed could reduce methane emissions from beef cattle as much as 82 percent, according to new findings from researchers at the University of California, Davis. The results, published today in the journal PLOS ONE, could pave the way for the sustainable production of livestock throughout the world.

“We now have sound evidence that seaweed in cattle diet is effective at reducing greenhouse gases and that the efficacy does not diminish over time,”

[…]

Over the course of five months last summer, Kebreab and Roque added scant amounts of seaweed to the diet of 21 beef cattle and tracked their weight gain and methane emissions. Cattle that consumed doses of about 80 grams (3 ounces) of seaweed gained as much weight as their herd mates while burping out 82 percent less methane into the atmosphere. Kebreab and Roque are building on their earlier work with dairy cattle, which was the world’s first experiment reported that used seaweed in cattle.

[…]

Results from a taste-test panel found no differences in the flavor of the beef from seaweed-fed steers compared with a control group. Similar tests with dairy cattle showed that seaweed had no impact on the taste of milk.

Also, scientists are studying ways to farm the type of seaweed—Asparagopsis taxiformis—that Kebreab’s team used in the tests. There is not enough of it in the wild for broad application.

Another challenge: How do ranchers provide seaweed supplements to grazing cattle on the open range? That’s the subject of Kebreab’s next study.

[…]

Source: Feeding cattle seaweed reduces their greenhouse gas emissions 82 percent

Also, do the bovines eat the seaweed happily or do they need to be force fed it?