The week’s most astounding developments from the neobiological frontier.

March 3, 2022

Heating beige fat: The future of weight loss?

Beige fat is a type of tissue that in the body looks exactly like ordinary white fat, but it can become activated by temperature and converted into mitochondria-laden brown fat, which the body burns for warmth, as proto.life reported earlier this year. Now researchers at East China Normal University in Shanghai and Shanghai Jiao Tong University have shown they could activate beige fat in humans and mice through local “hyperthermic” heating. The activation takes place due to the effect of a transcription factor protein called HSF1, which orchestrates cellular responses to heat stress. They also demonstrated that they could prevent and treat obesity in mice without adverse effects using hydrogels to locally apply heat. Cell

Eating seaweed helped evolve the human gut microbiome

Humans genetically lack the ability to produce the enzymes required to digest many of the complex polysaccharide sugar molecules found in fruits, vegetables, grains, and nuts. Luckily, far back in evolutionary history our guts became colonized with bacteria that do carry such enzymes, allowing us to make these foods our omnivorous starchy staples. According to researchers at the University of Michigan, Ann Arbor, and the Max Planck Institute for Marine Biology in Bremen, Germany, a second evolution of our gut microbiome occurred more recently when humans living in coastal regions began consuming red and brown seaweed—foods with such chemically different polysaccharides even our innate bacteria could not digest them. But the researchers showed that the human gut microbes acquired the necessary genes from marine bacteria, allowing us to appreciate the flavor and texture of these nutrient-dense sea vegetables. Cell Host & Microbe

The smoking gun of REM sleep

Scientists have known for years that when humans and other mammals sleep, we yo-yo cycle between various stages of rapid eye movement (REM) and non-REM sleep. But the underlying mechanism that triggers the shift from one to the other has never been understood. Now researchers at the University of Tsukuba in Japan have shown in studies involving mice that the secret lies in the basolateral amygdala region of the brain, where neurons release transient blasts of dopamine during non-REM sleep, triggering other neurons that carry the protein dopamine receptor D2 (Drd2) and initiating REM sleep. This mechanism plays a role in cataplectic attacks, the sudden loss of voluntary muscle control suffered by people with narcolepsy. Their work helps explain the pathology of narcolepsy, the authors write, and it may help us understand the pathology of REM sleep behavior disorder as well as the abnormal dopamine signaling seen in Parkinson’s disease. Science

Longevity through muscle building: It takes less than you think

A systematic review and meta-analysis of 16 clinical studies that looked at the impact of muscle-building exercise on lifespan—independent of aerobic exercise—showed that muscle-strengthening was associated with a 10–17 percent lower risk of all-cause mortality as well as risk of cardiovascular disease, diabetes, and lung cancer. There was no association found between muscle-strengthening and the risk of cancers of the colon, kidney, bladder, and pancreas. However, the longevity benefit of this form of exercise followed a J-shaped curve, meaning people maximized it after approximately 30–60 minutes of exercise per week. The influence of a greater weekly amount of muscle-strengthening on all-cause mortality is unclear, write the authors of the study, based at Tohoku University in Sendai, Japan. British Journal of Sports Medicine

The nostalgia effect: Pain ain’t like it used to be

Good things can happen when you fondly recall the past, including what you might call the “nostalgia effect,” a phenomenon whereby remembrance of things past reduces your perception of pain. Now scientists at the Chinese Academy of Sciences in Beijing used fMRI of 34 people viewing a series of pictures of objects or scenes from their own childhoods or pictures of similar things today—all while they were subjected to painful heat pulses on their arms. The researchers showed that the nostalgia effect is due to reduced activity in the brain’s lingual and parahippocampal gyrus and also involved the thalamus, a critical brain region for pain modulation. The findings may help develop non-drug, psychological forms of analgesia, the researchers write. The Journal of Neuroscience