But some rare metabolic diseases, such as hypolipidemia and Tangier disease, seem to work in reverse--they severely limit the amount of fat and cholesterol that makes it into the bloodstream. Researchers from the Carnegie Institution and the University of Pennsylvania have found a specific gene that could be responsible for such conditions; when the gene is disrupted, so is the ability to absorb lipids (fatty substances that include cholesterol) through the intestine.
Zebrafish larvae with a lethal mutation affecting fat metabolism (ffr) look the same as normal larvaes (wt) under normal magnification (left). However, when the embryos ingest lipid molecules labeled with...
In their latest research, published in the April 4 issue of the journal Cell Metabolism, Steve Farber of Carnegie’s Department of Embryology and Michael Pack, of the University of Pennsylvania School of Medicine describe their efforts to locate a gene called fat free within the genome of the zebrafish. These fish have become popular research organisms because their embryos are transparent, allowing studies that are not possible with traditional model organisms, such as mice and rats. Farber and Pack found that, despite the distant evolutionary relation between humans and zebrafish, the fat free gene in zebrafish is quite similar to a pair of human genes.
The researchers also explore the physical effects of a specific mutation of the gene, seeking to explain why larval fish with the mutation exhibit an impaired ability to absorb cholesterol. These fish die when they are about a one-and-a-half weeks old because of this defect, even though they look normal and swallow properly.
"There is a lot we still don’t know about how animals absorb, transport, and otherwise manage lipids," Farber said. "The fact that just one gene can have such a huge effect is encouraging, because it might reveal a means for treatment of human disease."
The scientists began by looking for structural defects in the mutants’ digestive organs. Their livers have abnormalities in the cells and ducts that produce bile--a salty, somewhat soapy fluid that helps lipid digestion. Certain pancreatic cells are also flawed, interfering with the production of digestive enzymes necessary for the breakdown of complex lipid molecules.
More importantly, the mutants also have defects in the cells that line the intestine, where fat and cholesterol absorption takes place. Normally, globules of lipid pass into these cells in small sacs called vesicles. These vesicles connect with the Golgi apparatus, a labyrinth of membranes filled with enzymes that modify the fats, and then new vesicles transport the fats out of the cell and into the bloodstream. The researchers found that this process is disrupted in the fat free mutants, preventing fats from reaching the bloodstream, and thereby depriving the animal of needed lipids.
Farber and Pack used a strategy called positional cloning both to locate fat free in the zebrafish genome and to determine its sequence. They found that the gene shares 75 percent of its sequence with a human gene called ANG2 (Another New Gene 2), which up to this time has had no known function. It also shares parts of its sequence with a gene called COG8, which is known to affect the Golgi apparatus. They also found that a change in only one base--one "letter" in the DNA code--results in the lethal mutation in zebrafish.
"This gene is absolutely necessary for cholesterol absorption--without it, the animals die," Farber said. This is encouraging for Pack, a physician-scientist in Penn’s Department of Medicine, "If we can understand this process in zebrafish, perhaps we can take what we learn and apply it to similar genes in humans, which could in turn lead to treatment for lipid metabolism disorders."
Bare bones: Making bones transparent
27.04.2017 | California Institute of Technology
Link Discovered between Immune System, Brain Structure and Memory
26.04.2017 | Universität Basel
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
27.04.2017 | Life Sciences
27.04.2017 | Physics and Astronomy
27.04.2017 | Earth Sciences