Tag: Cellular Processes

Block an Enzyme, Save a Life

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Vern Schramm in his lab, dressed in a white lab coat, standing with his arms folded across his chest. Vern Schramm, professor of biochemistry at Albert Einstein College of Medicine, Bronx, New York. Credit: Albert Einstein College of Medicine.

Enzymes drive life. Without them, we couldn’t properly digest food, make brain chemicals, move—or complete myriad other vital tasks. Unfortunately, in certain cases, enzymes also can trigger a host of health problems, including cancer, bacterial infections, and hypertension (high blood pressure).

Understanding how enzymes work has been the research focus of Vern Schramm for more than 4 decades.

“When we started our work, we were driven not by the desire to find drugs, but to understand the nature of enzymes, which are critical to human life,” Schramm says. But his research already led to one drug, and promises many more.

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Fabulous Fats in Your Holiday Feast

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Happy Thanksgiving!

During this time of year, family and friends gather to enjoy rich foods and good company. Even if you typically follow a healthy diet, it can be hard to make wholesome food choices during occasions like these.

Our previous post, Five Fabulous Fats, highlighted essential fats made in our bodies. Here we discuss five important fats our bodies can’t make on their own, the foods that contain them, and why you should include a healthy dose of each in your diet.

Geranial

Whole and sliced lemons, two jars of lemon oil, and lemon leaves on a wooden table.
Credit: iStock.

Geranial, a fat some people may not know about, is present in the oils of several citrus plants such as orange, lemon, and lime. Research suggests that its antibacterial and antimicrobial properties reduce inflammation in the body. So, think about adding some freshly squeezed lemonade to the menu.

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Interview With a Scientist: Unlocking the Secrets of Animal Regeneration With Alejandro Sánchez Alvarado

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Most of what we know comes from intensive study of research organisms—mice, fruit flies, worms, zebrafish, and a few others. But according to Alejandro Sánchez Alvarado Link to external web site, a researcher at the Stowers Institute for Medical Research in Kansas City and a Howard Hughes Medical Institute Investigator, these research organisms represent only a tiny fraction of all animal species on the planet. Under-studied organisms could reveal important biological phenomena that simply don’t occur in the handful of models typically studied, he says.

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RNA Polymerase: A Target for New Antibiotic Drugs?

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DNA, with its double-helix shape, is the stuff of genes. But genes themselves are only “recipes” for protein molecules, which are molecules that do the real heavy lifting (or do much of the work) inside cells.

RNAP illustrated as a crab claw, clamping on a DNA double helix. Artist interpretation of RNAP grasping and unwinding a DNA double helix. Credit: Wei Lin and Richard H. Ebright.

Here’s how it works. A molecular machine called RNA polymerase (RNAP) travels along DNA to find a place where a gene begins. RNAP uses a crab-claw-like structure to grasp and unwind the DNA double helix at that spot. RNAP then copies (“transcribes”) the gene into messenger RNA (mRNA), a molecule similar to DNA.

The mRNA molecule travels to one of the cell’s many protein-making factories (ribosomes), which use the mRNA message as instructions for making a specific protein.

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Cilia: Tiny Cell Structures With Mighty Functions

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Black-and-white video of cilia lining a cell wall and waving back and forth. Credit: Zvonimir Dogic, Brandeis University.

Imagine an army of tiny soldiers stationed throughout your body, lining cells from your brain to every major organ system. Rather than standing at attention, this tiny force sweeps back and forth thousands of times a minute. Their synchronized action helps move debris along the ranks to the nearest opening. Other soldiers stand as sentries, detecting changes in your environment, relaying that information to your brain, and boosting your senses of taste, smell, sight, and hearing.

Your brain may be the commander in chief, but these rank-and-file soldiers are made up of microscopic cell structures called cilia (cilium in singular).

Here we describe these tiny but mighty cell structures in action.

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Five Fabulous Fats

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Happy Fat Tuesday!

On this day, celebrated in many countries with lavish parties and high-fat foods, we’re recognizing the importance of fats in the body.

You’ve probably heard about different types of fat, such as saturated, trans, monounsaturated, omega-3, and omega-6. But fats aren’t just ingredients in food. Along with similar molecules, they fall under the broad term lipids and serve critical roles in the body. Lipids protect your vital organs. They help cells communicate. They launch chemical reactions needed for growth, immune function, and reproduction. They serve as the building blocks of your sex hormones (estrogen and testosterone).

Here we feature five of the hundreds of lipids that are essential to health.

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Molecular Fireworks: How Microtubules Form Inside Cells

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A video depicting red strands of various lengths exploding outward from a focal point at the left. The strands are tipped in neon green.
       Microtubules sprout from one another. Credit: Petry lab, Princeton University.

The red spray pictured here may look like fireworks erupting across the night sky on July 4th, but it’s actually a rare glimpse of tiny protein strands called microtubules sprouting and growing from one another in a lab. Microtubules are the largest of the molecules that form a cell’s skeleton. When a cell divides, microtubules help ensure that each daughter cell has a complete set of genetic information from the parent. They also help organize the cell’s interior and even act as miniature highways for certain proteins to travel along.

As their name suggests, microtubules are hollow tubes made of building blocks called tubulins. Scientists know that a protein called XMAP215 adds tubulin proteins to the ends of microtubules to make them grow, but until recently, the way that a new microtubule starts forming remained a mystery.

Sabine Petry Link to external web site and her colleagues at Princeton University developed a new imaging method for watching microtubules as they develop and found an important clue to the mystery. They adapted a technique called total internal reflection fluorescence (TIRF) microscopy, which lit up only a tiny sliver of a sample from frog egg (Xenopus) tissue. This allowed the scientists to focus clearly on a few of the thousands of microtubules in a normal cell. They could then see what happened when they added certain proteins to the sample.

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CLAMP Helps Lung Cells Pull Together

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ALT TEXTCells covered with cilia (red strands) on the surface of frog embryos. Credit: The Mitchell Lab.

The outermost cells that line blood vessels, lungs, and other organs also act like guards, alert and ready to thwart pathogens, toxins, and other invaders that can do us harm. Called epithelial cells, they don’t just lie passively in place. Instead, they communicate with each other and organize their internal structures in a single direction, like a precisely drilled platoon of soldiers lining up together and facing the same way.

Lining up this way is crucial during early development, when tissues and organs are forming and settling into their final positions in the developing body. In fact, failure to line up in the correct way is linked to numerous birth defects. In the lungs, for instance, epithelial cells’ ability to synchronize with one another is important since these cells have special responsibilities such as carrying mucus up and out of lung tissue. When these cells can’t coordinate their functions, disease results.

Some lung epithelial cells are covered in many tiny, hair-like structures called cilia. All the cilia on lung epithelial cells must move uniformly in a tightly choreographed way to be effective in their mucus-clearing job. This is a unique example of a process called planar cell polarity (PCP) that occurs in cells throughout the body. Researchers are seeking to identify the signals cells use to implement PCP. Continue reading “CLAMP Helps Lung Cells Pull Together”

Pericytes: Capillary Guardians in the Brain

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The long arms of pericytes cells (red) stretch along capillaries (blue) in a mouse brain. Credit: Andy Shih.

Nerve cells, or neurons, in our brains do amazing work, from telling our hearts to beat to storing our memories. But neurons cannot operate alone. Many kinds of cells support and regulate neurons and—like neurons—they can come under attack due to injuries or disorders, such as stroke or Alzheimer’s disease. Learning what jobs these cells do and how they respond to disease may show researchers new ways to treat central nervous system disorders. One type of support cell, the pericyte, plays some key roles in brain health. These cells are readily adaptable, even in adult brains, and can support a variety of functions.

Pericytes help with blood flow to nerve cells in the brain. They lie wrapped all along the huge networks of capillaries—the tiniest blood vessels—that both feed neurons and form the blood-brain barrier, which filters out certain substances from blood to protect the brain. Pericytes have a body that appears as a bump protruding from a capillary surface. Pericytes also have long thin arms that stretch along each capillary like a snake on a tree branch. These arms, called processes, reach almost to where the next pericyte process begins, without overlapping. This creates a pericyte chain that covers nearly the entire capillary network.

Pericytes are critical for blood vessel stability and blood-brain barrier function. They’re also known to die off as a result of trauma and disease. Andy ShihLink to external web site, Andree-Ann Berthiaume, and colleagues at the Medical University of South Carolina in Charleston, set up an imaging technique in mouse brains that allowed them to see what pericytes do under normal conditions as well as how these cells respond when some are damaged.

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