Monthly Archives: November 2013

Does Obesity Reshape Our Sense of Taste?

In a Nov. 13 study in the journal PLOS ONE, University at Buffalo biologists report that being severely overweight impaired the ability of mice to detect sweets.

Compared with slimmer counterparts, the plump mice had fewer taste cells that responded to sweet stimuli. What’s more, the cells that did respond to sweetness reacted relatively weakly.

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The findings peel back a new layer of the mystery of how obesity alters our relationship to food.

“Studies have shown that obesity can lead to alterations in the brain, as well as the nerves that control the peripheral taste system, but no one had ever looked at the cells on the tongue that make contact with food,” said lead scientist Kathryn Medler, PhD, UB associate professor of biological sciences.

“What we see is that even at this level — at the first step in the taste pathway — the taste receptor cells themselves are affected by obesity,” Medler said. “The obese mice have fewer taste cells that respond to sweet stimuli, and they don’t respond as well.”

The research matters because taste plays an important role in regulating appetite: what we eat, and how much we consume.

How an inability to detect sweetness might encourage weight gain is unclear, but past research has shown that obese people yearn for sweet and savory foods though they may not taste these flavors as well as thinner people.

Medler said it’s possible that trouble detecting sweetness may lead obese mice to eat more than their leaner counterparts to get the same payoff.

Learning more about the connection between taste, appetite and obesity is important, she said, because it could lead to new methods for encouraging healthy eating.

“If we understand how these taste cells are affected and how we can get these cells back to normal, it could lead to new treatments,” Medler said. “These cells are out on your tongue and are more accessible than cells in other parts of your body, like your brain.”

The new PLOS ONE study compared 25 normal mice to 25 of their littermates who were fed a high-fat diet and became obese.

To measure the animals’ response to different tastes, the research team looked at a process called calcium signaling. When cells “recognize” a certain taste, there is a temporary increase in the calcium levels inside the cells, and the scientists measured this change.

The results: Taste cells from the obese mice responded more weakly not only to sweetness but, surprisingly, to bitterness as well. Taste cells from both groups of animals reacted similarly to umami, a flavor associated with savory and meaty foods.

Medler’s co-authors on the study were former UB graduate student Amanda Maliphol and former UB undergraduate Deborah Garth.

 

 

 

 

 

 

Source: Sciencedaily

How Whales Could Adapt to Ocean?

Whales roam throughout all of the world’s oceans, living in the water but breathing air like humans. At the top of the food chain, whales are vital to the health of the marine environment, whereas 7 out of the 13 great whale species are endangered or vulnerable. The minke whale is the most abundant baleen whale. Its wide distribution makes it an ideal candidate for whole reference genome sequencing.

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In this study, researchers conducted de novo sequencing on a minke whale with 128x average depth of coverage, and re-sequenced three minke whales, a fin whale (Balaenoptera physalus), a bottlenose dolphin, and a finless porpoise (Neophocaena phocaenoides). The yielded data may help to improve scientists’ understanding of the evolutionary changes adapted to ocean environment from whole genome level.

The adaptation of whale to ocean life was notably marked by resistance to physiological stresses caused by a lack of oxygen, increased reactive oxygen species, and high salt level. In this study, researchers investigated a number of whale-specific genes that were strongly associated with stress resistance, such as the peroxiredoxin (PRDX) family, O-linked N-acetylglucosaminylation (O-GlcNAcylation). The results revealed that the gene families associated with stress-responsive proteins and anaerobic metabolism were expanded.

Perhaps the most dramatic environmental adaptation for a whale is deep diving, which can induce hypoxia. Under the hypoxic conditions, the body might produce more reactive oxygen species (ROS), harmful compounds that can damage DNA. Glutathione is a well-known antioxidant that prevents damage to important cellular components by ROS. In this study, researchers provided evidence to support that there is an increased ratio of reduced glutathione/glutathione disulfide when suffering hypoxic or oxidative stress.

Minke whales and other Mysticeti whale species grow baleen instead of teeth. It’s previously reported that the genes ENAM, MMP, and AMEL might play a role in tooth enamel formation and biomineralization. This study showed that these genes may be pseudogenes with early stop codons in the baleen whales. In addition, researchers found that the gene families related to whale’s body hair and sensory receptors were contracted, such as Keratin-related gene families associated with hair formation, several Hox genes that play an important role in the body plan and embryonic development.

Xuanmin Guang, project manager from BGI, said, “Minke whale is the first marine mammal that has been sequenced with such high-depth genome coverage. The genome data not only can help us know much more about the adaption mechanisms underlying minke whale, but also provides invaluable resource for marine mammal’s future studies such as diseases control and prevention, species conservation,and protection.”

 

 

 

 

 

Source: Sciencedaily

The Subjectiveness of Time

We like stability. We like to know that each day the Sun is going to rise, the mailman will bring our paper, and time will march slowly on — just the same as it always has. What’s more, we like to image that this experience is larger than ourselves. When the Sun rises, we know that it’s rising for everyone, not just for us. When the mailman brings the paper, he isn’t making a special trip; he’ll stop at the neighbors as well. These are the common, everyday experiences that unite is all.

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However, as it turns out, we are a bit more isolated that we might initially assume.

 

 

When Albert Einstein introduced his Theory of Relativity, he argued that space-time is curved and warped by the existence of matter. To understand this, imagine a kitten playing on a stretched out blanket. Depending on where it is standing, the weight of the kitten will warp the blanket, forming a slight dip in the otherwise even sheet.

 

If the Earth is a kitten, then the blanket is space-time. And much like the kitten, Earth causes a slight warping of the blanket that is space-time. This means that time will appear to move slower near massive objects (like Earth) because space-time is warped by mass. In 1962, these predictions were proven when scientists placed an atomic clock at the bottom and top of a water tower. The clock at the bottom (the one closer to the massive center of the Earth) was running slower than the clock at the top.

 

In short, our location alters how we experience time. Admittedly, the time difference is so slight that we don’t notice it. But it is different nonetheless.

 

And it seems that it’s not just literal time that is different; our perception of literal time also differs from person to person. This is because our neurons impact how we perceive time. In 2012, scientists from the University of Minnesota conducted research which demonstrated that, in the brain, different neural circuits have their own timing mechanisms for specific activities. This find could explain why time seems to pass so slowly when you are listening to a lecture, and why time flies by when you are listening to your favorite band. Moreover, the researchers note that the perception mechanisms alter slightly from person to person—so a lecture might go by slowly to me, while it goes by REALLY slowly to you.

 

So in some ways, when you walk past someone on the street (unless you are walking at the exact same speed), you are walking through a different measurement of time. Ultimately, this is just one (very simplified) way of highlighting how, scientifically, you live in your own unique world which only you are able to experience.

 

 

 

Source: fromquarkstoquasars