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We use this blog to share with the Nazareth community the best scientific writing by the students enrolled in this class. Stay posted for articles on cutting edge science that will be made easily understandable to those outside of our field and perhaps, why not, reports on our own research.
Your comments are always welcome!
by Emily Benton
‘Tis the season to be jolly…. and on the road driving to family and friends for the holiday, spending an obscene amount of money on gas. “I remember when gas was five cents a gallon,” says Grandpa Joe. Well, what if there was a way to make gas cheaper, environmentally friendly, and less toxic? We will probably never see the price of gas at five cents a gallon again, but it would be nice if we didn’t have to pay the almost-four-dollar prices we’re seeing today. Studies have found that by reversing a simple reaction may have the potential of efficiently providing the resources for producing fuel. We all know what that means—more efficient means less money!
The production of fuels (and other chemicals) that consists of long, linear chains of carbon and hydrogens (a.k.a fatty acids) involves several condensation reactions, making carbon-to-carbon bonds. One example of this type of condensation reaction is what has been referred to as reverse β-oxidation. Regular β-oxidation is a series of reactions that degrade a long, fatty acid chain into several smaller two-carbon molecules of acetyl-CoA; therefore, reverse β-oxidation is the opposite of that, making long-chain alcohols and fatty acids (Nelson et al.2005) (Figure 1).
Unlike regular β-oxidation, reverse β-oxidation must be able to operate on sources other than fatty-acids. The pathway of reverse β-oxidation utilizes acetyl-CoA, other coenzyme A- containing molecules, and a set of what are known as termination enzymes that includes thiolases (transfer acetyl-CoA), dehydrogenases (transfer a hydride, :H-), reductases (add electrons, such as the case of forming a bond) and thioestersaes (make alcohols and acids from an ester). As discovered in the study of Dellomonaco and other researchers, certain genes in Escherichia coli that code for these termination enzymes must be triggered in order for them to be expressed. This reaction takes place when generating even-chains. When producing odd-chains, which are less often seen in nature, a three-carbon molecule containing coenzyme A is used instead of acetyl-CoA. Other condensation reactions require the activation of malonyl-CoA, which requires energy, while reverse β-oxidation does not, making it much more efficient (Dellomonaco et al. 2011).
One of the significances of reverse β-oxidation is its ability to regenerate the chemicals that are needed for producing fuel. An increasingly popular alternative fuel is biodiesel, which is produced from vegetable oils (a fatty acid) and alcohol, such as methanol. When fatty acid and methanol react, a fatty acid methyl ester (FAME) forms, which is essentially fuel. However, often times the vegetable oils are already used (cooking oil) and need to be purified before producing FAME. It is also sometimes difficult to obtain enough used oil. Therefore, if reverse β-oxidation ends up being cost efficient when producing mass amounts of fatty acids, these fatty acids can be used for producing FAME (Diesel Fuel).
The use of biodiesel fuel over petroleum has many benefits. First of all, it is biodegradable and nontoxic, making it environmentally friendly. For instance, biodiesel fuel has a significantly lower amount of sulfur. The adverse affects of sulfur is that it forms sulfur oxides and sulfates that can make acid rain, which has been found to be very corrosive. Secondly, the use of biodiesel lowers carbon monoxide (CO) emissions by 50% and lowers emissions of particulate matter by 30%. Also, using biodiesel instead of petroleum has recently been found to reduce the amount of carcinogens in the atmosphere by an average of 75%, which is a lower health risk for people (Diesel Fuel). Biodiesel fuel is also more economical due to the increasing prices of crude oil and limited supply of fossil fuels (Ma et al. 1999).
Alternative fuels are necessary, especially with the economy the way it is today. Several studies have discovered new ways of producing these alternative fuels, but one problem that still arises is energy cost. This study has been able to reverse the naturally occurring process of β-oxidation that condenses small organic molecules into long chains that may result in less expensive fuel one day.
References
by Jessica Ellis
Cardiovascular Disease (CVD) - a generic term to describe a multitude of disorders that affect one’s heart, is one of the leading causes of death in the United States. This disease is caused by deposits of cholesterol, lipids and fat building on a person’s arteries making them non-elastic and narrow. Previous studies have blamed the accumulation of cholesterol and fats in the body due to genetics. Others have accused inadequate regulation of energy balance, what you eat. Recent studies, however, have even begun to focus on the central nervous system as a cause for CVD. Some studies have involved the observation of lesions, mutations in cells, in a section of the brain called the hypothalamus, which results in obesity. A study conducted by Diego Perez-Tilve et al. at the Metabolic Diseases Institute of University of Cincinnati proposes that he central nervous system has an effect on the production of cholesterol and fat build up in the body. They suggest that through better understanding of how the central nervous system promotes or represses specific hormones and proteins new therapies can be developed for the elimination of obesity, diabetes and hypertension.
Perez-Tilve et al. discovered Leptin, a hormone produced in the central nervous system, to be a hormone that inhibits a person’s appetite. They also observed that the hormone had an influential role in the manufacture of the “good” cholesterol, high density lipoprotein (HDL). They found that mice injected with leptin increase the amount of HDL in their blood stream. When mice were not subjected to increased amounts of Leptin.their HDL was lower. In addition to the production of “good” cholesterol being influenced by leptin, this hormone also affects the elimination of cholesterol through bile production and emission. Bile is formed in the liver and aids in the digestion of fat and cholesterol. With leptin production increased, the removal of excess fat in the body can be conducted quicker and more efficiently. Perez-Tilve et al. state however, that they do not know of the process in which the central nervous system and leptin controls the production of bile and HDL and suggest further study should be conducted to aid in this innovative weight loss system.
Another method of how the central nervous system affects cholesterol and fat production is through the neuropeptide Y (NPY). NPY is a neurotransmitter, a chemical that passes information between cells. NPY is located in the hypothalamus that controls feeding and energy balance. Perez-Tilve et al. observed that mice injected with NPY increases production of low density lipoprotein (LDL), the “bad” cholesterol. The reason why LDL is considered “bad” cholesterol is that it binds to the walls of the arteries inducing atherosclerosis. With the discovery of the effects of NPY production by the central nervous system the ability to help eliminate VLDL is in near sight.
Family history, a person’s metabolism and food intake are usual suspects for cardiovascular disease. However, a new suggestion for obesity, diabetes, and hypertension from Perez-Tilve et al. is the central nervous system. They propose that the amount of the hormone leptin and the neurotransmitter NYP controlled by the central nervous system influence the quantity of cholesterol and fat in the body. Additional research needs to be conducted to better understand the process of these molecules on cholesterol and fat production in hopes of developing a new technique for weight loss. Who would have guessed the brain would be a factor in the struggle for a healthy heart.
References:
Vampire bats feed on warm blooded animals, using heat sensors in the nose to locate blood flow. An alteration of the TRPV1 protein in the sensory neurons of vampire bats has been discovered as the mechanism behind their ability to sense heat.
by Alison Kochersberger
Emerging at night to feed, the vampire bat diet consists exclusively of the blood of sleeping animals. They will not remove enough blood to cause harm to the host. The habitat of vampire bats spans from Mexico to South America. Although it is not common, they have been known to feed on humans. The vampire bat lands close to and crawls towards its prey, using its heat-sensing ability to locate where blood is flowing on the host. This heat sensor is located in the nose of the bat. The shape of the vampire bat’s nose differs from the fruit bat, which does not feed on blood. It is the three ‘leaf pits’ on the nose of the vampire bat that give it the ability to locate blood flow on its victim in the form of infrared (heat) stimuli.
When investigating the function behind the ability to detect heat within these ‘leaf pits’, researchers found that the sensory nerves were larger, as they are in snakes that can detect infrared. Other types of nerves were observed to have the same structure as in bats that cannot detect heat. Because of this observation, researchers wanted to find if there was a genetic difference in these sensory nerves from the nerves that serve other functions.
They compared the genetic sequences for the sensory nerves and normal nerves. The researchers found that there was an alteration in TRPV1, a capsaicin receptor, a protein, that is activated by temperature. Capsaicin receptors also produce a burning sensation when consuming hot chili peppers. The alteration was due to a segment of the receptor being removed in a process called splicing, resulting in a shorter protein. It was found that the shorter protein had increased heat sensitivity, activating at a temperature 10°C lower than the long version of the receptor.
Next the researchers looked to see if this alteration occurred in other species. They found that other bats and moles could all undergo a similar modification of shortening this receptor. Cows, pigs and dogs could also experience a modification, but it would produce an extended protein. Although these alterations are possible, researchers found that they rarely occur, as heat sensing would not be needed in these animals. Rodents and humans could not have any modification, which suggests that vampire bats are more closely related to cows, dogs, and moles than rodents. It is also noted that zebrafish have an altered TRPV1 which increases their sensitivity to heat, although the alteration is achieved through a different mechanism than the vampire bat. This discovery demonstrates the ability of unrelated animals to evolve similar traits.
The ability of the vampire bat to locate and feed off of warm blood is something that has fascinated humans, which is reflected in the use of vampires in fiction. These researchers have started to unveil the secrets behind this creature’s unique feeding habits. This study demonstrates that without even changing the sequence of DNA, a new function can be created, such as sensing heat to help in the feeding process. Moving forward, other mechanisms of protein modification could be compared to determine relatedness of different species. It could also be investigated which modification provides the greatest heat sensitivity between bats, snakes, and zebrafish.
Gracheva, EO et al. 2011. Ganglion-specific splicing of TRPV1 underlies infrared sensation in vampire bats. Nature. 476: 88-92.
TRPV1 transient receptor potential cation channel, subfamily V, member 1 [ Homo sapiens ] [Internet]. NCBI. [updated 2011 Oct 30; cited 2011 Nov 7]. Available from: http://www.ncbi.nlm.nih.gov/gene/7442
Staphylococcus aureus, a cause for clotting in heart valves can now be located and quantified through prothrombin activation.
By Jessica Ellis
Once the glowing tag was placed onto the protein, the complex needed to be connected to the bacteria. This was conducted by the protein binding to staphylocoagulase, an enzyme produced by coagulase-positive Staphylococcus aureus that develops at the peripheral sides of the heart valves. The strength of the interaction between the enzyme and protein is very high which aided in the formation of the staphylocoagulase-prothrombin complex.
The next step for the team was to determine the molecular mechanism which would allow for the staphylocoagulase-prothrombin complex to bind to the heart valves. The binding was indentified to occur through fibrinogen fragment D (FragD), a blood clotting factor that travels through the heart valves. More than one FragD, four in total, could bind to a single staphylocogulase creating a megacomplex was determined. This megacomplex allowed for anchorage of the staphylocoagulase-prothrombin complex to the heart valve.
With the megacomplex anchorged to the heart valves, called AF680-ProT, detection of endocarditis was possible. Panizzi et al. found a high local concentration of AF680-ProT in a mouse’s heart valve after 24 hours of injection. However, when the experiment was repeated in heart valves not containing S. aureus, the signal for AF680-ProT was 20 to 28 times lower. This indicated the signaling is only induced by this specific pathogen. Quantification of the effects of antibiotic therapy on the levels of S. aureus in the heart valves was also recognized. He measured the amount of AF680-ProT when vancomycin, an antibiotic for S. aureus, was added to the mice and observed a decrease in AF680-ProT as vancomycin intake increased.
Today, blood cultures are used for acute endocarditis diagnosis. This strategy is time consuming and not pathogen specific. Panizzi and his research team have begun to investigate the use of glowing prothrombin bound to staphylocoagulase in S. aureus to quantify the amount of S. aureus in a mouse’s heart valve. Through the use of S. aureus targeted tracers the specific diagnosis of endocarditis could occur at a faster rate. The heart break over bacteria may end, all thanks to a glowing tag.
Panizzi, Peter. et al. "In vivo detection of Staphylococcus aureus endocarditis by targeting pathogen-specific prothrombin activation." Nature Medicine 17.9 (2011): 1142-1147.
File: Staphylococcus aureus VISA 2.jpg Wikipedia.
