November 15, 2017
Tax reform plan punishes grad students and could cost our country in long run | Comment
The Courier Journal
"..the new GOP tax plan, lawmakers want to repeal Sec. 117(d), allowing the tuition waivers graduate students receive to be taxed. Currently, the after-tax take-home for a graduate student is around $22.5K per year (varying by stipend amount and exemptions). If this section of the tax code is removed, take-home amount will drop to around $16K per year."
October 26, 2017
Real science for real life: Astronomy
"Hopefully many of you got to experience August’s Great American Solar Eclipse. Maybe it got you thinking about what else is going on up there among the stars.
There is a wide variety in the types of objects that can be found in our universe and we’re learning about new ones all the time. Each solar object could have a whole article devoted to it, so we’re going to have to cherry-pick some of the most exciting stellar phenomena."
August 27, 2017
Real science for real life: Time
"You probably haven’t spent much time thinking about time itself, have you? If you have, like many of us, you may have spiraled into an existential crisis. We hope after this article, however, that you have a better understanding of time without feeling perturbed."
March 06, 2017
Host FIH-Mediated Asparaginyl Hydroxylation of Translocated Legionella pneumophila Effectors
Price C, Merchant M, Jones S, Best A, Von Dwingelo J, Lawrenz MB, Alam N, Schueler-Furman O, Kwaik YA.
Abstract
FIH-mediated post-translational modification through asparaginyl hydroxylation of eukaryotic proteins impacts regulation of protein-protein interaction. We have identified the FIH recognition motif in 11 Legionella pneumophila translocated effectors, YopM of Yersinia, IpaH4.5 of Shigella and an ankyrin protein of Rickettsia. Mass spectrometry analyses of the AnkB and AnkH effectors of L. pneumophila confirm their asparaginyl hydroxylation. Consistent with localization of the AnkB effector to the Legionella-containing vacuole (LCV) membrane and its modification by FIH, our data show that FIH and its two interacting proteins, Mint3 and MT1-MMP are acquired by the LCV in a Dot/Icm type IV secretion-dependent manner. Chemical inhibition or RNAi-mediated knockdown of FIH promotes LCV-lysosomes fusion, diminishes decoration of the LCV with polyubiquitinated proteins, and abolishes intra-vacuolar replication of L. pneumophila. These data show acquisition of the host FIH by a pathogen-containing vacuole and that asparaginyl-hydroxylation of translocated effectors is indispensable for their function.
February 23, 2017
Real science for real life: Winter weather
"Winter officially started Dec. 21, 2016. The date is based on the winter solstice, when the northern hemisphere experiences the day of the year with the shortest daylight. The days get shorter approaching the winter solstice and longer after.
During this time of the year, the northern hemisphere is tilted away from the sun. The sun is lower in the sky, changing the angle at which the sun’s rays hit the Earth. These two factors are what contribute the colder climate in the winter.
Winter weather describes the day-to-day state of the atmosphere – what it is doing. Winter climate describes the overall trend in the weather on a long-term scale."
June 23, 2016
Real science for real life: Be a Forest Firebrand
"One key factor in the fight against forest fires is education. Understanding how your actions impact the environment could prevent accidental fires caused by campfires, smoking and equipment, or prevent others from considering acts of arson. The effects of climate change are already impacting our forests due to dryer weather; fire seasons are lengthening and fires are becoming more frequent in many zones that are prone to wildfires."
April 28, 2016
"As April fades away, we start to see a decline in the number of cases of flu and the common cold. We’ve always known that flu prefers the cold winter months – which led us to believe that being cold is what causes disease. However, researchers have shown that the viruses that causes the flu are more stable in cold, dry environments, thus we see a seasonal increase in the number of flu cases."
September 27, 2014
Code blue: Acinetobacter baumannii, a nosocomial pathogen with a role in the oral cavity.
Richards AM, Abu Kwaik Y, Lamont RJ.
Abstract
Actinetobacter baumannii is an important nosocomial pathogen that can cause a wide range of serious conditions including pneumonia, meningitis, necrotizing fasciitis and sepsis. It is also a major cause of wound infections in military personnel injured during the conflicts in Afghanistan and Iraq, leading to its popular nickname of 'Iraqibacter'. Contributing to its success in clinical settings is resistance to environmental stresses such as desiccation and disinfectants. Moreover, in recent years there has been a dramatic increase in the number of A. baumannii strains with resistance to multiple antibiotic classes. Acinetobacter baumannii is an inhabitant of oral biofilms, which can act as a reservoir for pneumonia and chronic obstructive pulmonary disease. Subgingival colonization by A. baumannii increases the risk of refractory periodontitis. Pathogenesis of the organism involves adherence, biofilm formation and iron acquisition. In addition, A. baumannii can induce apoptotic cell death in epithelial cells and kill hyphal forms of Candida albicans. Virulence factors that have been identified include pili, the outer membrane protein OmpA, phospholipases and extracellular polysaccharide. Acinetobacter baumannii can sense blue light through a blue-light sensing using flavin (BLUF) domain protein, BlsA. The resulting conformational change in BlsA leads to changes in gene expression, including virulence genes.
July 24, 2014
Nutrient generation and retrieval from the host cell cytosol by intra-vacuolar Legionella pneumophila.
October 21, 2013
Amoeba host-Legionella synchronization of amino acid auxotrophy and its role in bacterial adaptation and pathogenic evolution
Price CT, Richards AM, Von Dwingelo JE, Samara HA, Abu Kwaik Y.
Abstract
Legionella pneumophila, the causative agent of Legionnaires' disease, invades and proliferates within a diverse range of free-living amoeba in the environment, but upon transmission to humans, the bacteria hijack alveolar macrophages. Intracellular proliferation of L. pneumophila in two evolutionarily distant hosts is facilitated by bacterial exploitation of conserved host processes that are targeted by bacterial protein effectors injected into the host cell. A key aspect of microbe-host interaction is microbial extraction of nutrients from the host, but understanding of this is still limited. AnkB functions as a nutritional virulence factor and promotes host proteasomal degradation of polyubiquitinated proteins generating gratuitous levels of limiting host cellular amino acids. Legionella pneumophila is auxotrophic for several amino acids including cysteine, which is a metabolically preferred source of carbon and energy during intracellular proliferation, but is limiting in both amoebae and humans. We propose that synchronization of bacterial amino acids auxotrophy with the host is a driving force in pathogenic evolution and nutritional adaptation of L. pneumophila and other intracellular bacteria to life within the host cell. Understanding microbial strategies of nutrient generation and acquisition in the host will provide novel antimicrobial strategies to disrupt pathogen access to essential sources of carbon and energy.
March 27, 2013
Cellular microbiology and molecular ecology of Legionella-amoeba interaction.
Richards AM, Von Dwingelo JE, Price CT, Abu Kwaik Y
Abstract
Legionella pneumophila is an aquatic organism that interacts with amoebae and ciliated protozoa as the natural hosts, and this interaction plays a central role in bacterial ecology and infectivity. Upon transmission to humans, L. pneumophila infect and replicate within alveolar macrophages causing pneumonia. Intracellular proliferation of L. pneumophila within the two evolutionarily distant hosts is facilitated by bacterial exploitation of evolutionarily conserved host processes that are targeted by bacterial protein effectors injected into the host cell by the Dot/Icm type VIB translocation system. Although cysteine is semi-essential for humans and essential for amoeba, it is a metabolically favorable source of carbon and energy generation by L. pneumophila. To counteract host limitation of cysteine, L. pneumophila utilizes the AnkB Dot/Icm-translocated F-box effector to promote host proteasomal degradation of polyubiquitinated proteins within amoebae and human cells. Evidence indicates ankB and other Dot/Icm-translocated effector genes have been acquired through inter-kingdom horizontal gene transfer.
December 20, 2012
Effect of Ethanol on Differential Protein Production and Expression of Potential Virulence Functions in the Opportunistic Pathogen Acinetobacter baumannii
Nwugo CC, Arivett BA, Zimbler DL, Gaddy JA, Richards AM, Actis LA.
Abstract
Acinetobacter baumannii persists in the medical environment and causes severe human nosocomial infections. Previous studies showed that low-level ethanol exposure increases the virulence of A. baumannii ATCC 17978. To better understand the mechanisms involved in this response, 2-D gel electrophoresis combined with mass spectrometry was used to investigate differential protein production in bacteria cultured in the presence or absence of ethanol. This approach showed that the presence of ethanol significantly induces and represses the production of 22 and 12 proteins, respectively. Although over 25% of the ethanol-induced proteins were stress-response related, the overall bacterial viability was uncompromised when cultured under these conditions. Production of proteins involved in lipid and carbohydrate anabolism was increased in the presence of ethanol, a response that correlates with increased carbohydrate biofilm content, enhanced biofilm formation on abiotic surfaces and decrease bacterial motility on semi-solid surfaces. The presence of ethanol also induced the acidification of bacterial cultures and the production of indole-3-acetic acid (IAA), a ubiquitous plant hormone that signals bacterial stress-tolerance and promotes plant-bacteria interactions. These responses could be responsible for the significantly enhanced virulence of A. baumannii ATCC 17978 cells cultured in the presence of ethanol when tested with the Galleria mellonella experimental infection model. Taken together, these observations provide new insights into the effect of ethanol in bacterial virulence. This alcohol predisposes the human host to infections by A. baumannii and could favor the survival and adaptation of this pathogen to medical settings and adverse host environments.