Physiology Commons^™

Editorial: Pharmacology Of Endocrine Related Gpcrs, Francesco De Pascali, Aylin Hanyaloglu, Frederic Jean-Alphonse, Francesco Potì, Eric Reiter

Department of Biochemistry and Molecular Biology Faculty Papers

No abstract provided.

Invited Review: Adrenocortical Function In Avian And Non-Avian Reptiles: Insights From Dispersed Adrenocortical Cells., Rocco V. Carsia, Patrick J. Mcilroy, Henry B John-Alder

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Herein we review our work involving dispersed adrenocortical cells from several lizard species: the Eastern Fence Lizard (Sceloporus undulatus), Yarrow's Spiny Lizard (Sceloporus jarrovii), Striped Plateau Lizard (Sceloporus virgatus) and the Yucatán Banded Gecko (Coleonyx elegans). Early work demonstrated changes in steroidogenic function of adrenocortical cells derived from adult S. undulatus associated with seasonal interactions with sex. However, new information suggests that both sexes operate within the same steroidogenic budget over season. The observed sex effect was further explored in orchiectomized and ovariectomized lizards, some supported with exogenous testosterone. Overall, a suppressive effect of testosterone was evident, especially in cells …

Observing Ceramide Pathway With Ferroptosis Via Mia Paca-2 Cell Treatment With Rsl3, Tazrin Rahman

Auctus: The Journal of Undergraduate Research and Creative Scholarship

Composed of sphingosine and a fatty acid, ceramides are lipid molecules that serve as key metabolic signaling molecules of a sphingolipid pathway. While it acts as a precursor of complex sphingolipids, inducing ceramide generation can cause cell stress leading to subsequent cell death via apoptosis, necrosis, and even mitophagy. With regards to cell death specifically, a novel form of regulated cell death, ferroptosis, has recently been recognized of necrotic nature. Its unique morphological features and distinct properties have been observed over the last several decades; however, the molecular features were not identifiable as pure evidence of cell death, until recently …

Exploring Indicator Displacement Assays For Phosphate Detection In Seawater, Francis Radics

Chemistry & Biochemistry Student Scholarship

Francis Radics ’22
Major: Biochemistry
Faculty Mentor: Dr. John Breen, Chemistry and Biochemistry

Indicator displacement assays are based on the optical signal modulation of a noncovalently bound indicator upon dissociation by an analyte species. Our work has focused on exploring the lower detection limits for luminescent displacement assays for inorganic phosphate in seawater using complex ions containing two di(2-picolyl)amine ligands (also called DPA or bis(2-pyridylmethyl)amine), each coordinating a zinc cation. Following the work of B.D. Smith and coworkers, we have prepared three ligands by covalently attaching two DPA moieties, 2,6-bis(chloromethyl) benzene, and 2,6-bis(chloromethyl)-4-methylphenol, and 1,2-phenylenedimethylamine, for assays with 6,7-dihydroxy-4-methanesulfonic acid …

Investigation Of Oncogenic Ras And Endoplasmic Reticulum-Mitochondria Calcium Flux And Their Relationship In The Context Of Tumorigenesis, Emma Anderson

Senior Honors Theses

Intracellular calcium as a signaling molecule is a pervasive feature of cellular pathways, especially those that manage internal homeostasis and transitions through the cell cycle, so much so that regulated, responsive calcium flux between the endoplasmic reticulum (ER) and the mitochondria has been suggested to play a major role in cancer development. Another factor commonly implicated in tumorigenesis is RAS, an oncogene that controls signaling for many pathways that are also regulated by calcium. While both calcium and oncogenic RAS signaling are implicated in cancer development, possible links between them have yet to be determined. The identification of these links …

Anatomy And Physiology Preparatory Course Textbook (2nd Edition), Carlos Liachovitzky

Open Educational Resources

The goal of this preparatory textbook is to give students a chance to become familiar with some terms and some basic concepts they will find later on in the Anatomy and Physiology course, especially during the first few weeks of the course.

Organization and functioning of the human organism are generally presented starting from the simplest building blocks, and then moving into levels of increasing complexity. This textbook follows the same presentation. It begins introducing the concept of homeostasis, then covers the chemical level, and later on a basic introduction to cellular level, organ level, and organ system level. This …

High And Low Toxin Producing Strains Of Karenia Brevis Differ Significantly In The Redox Proteome, Lipid Profiles, And Xanthophyll Cycle Pigments, Ricardo Colon

FIU Electronic Theses and Dissertations

The dinoflagellate Karenia brevis, blooms annually in the Gulf of Mexico, producing a suite of neurotoxins known as the brevetoxins. The cellular toxin content of K. brevis, however, is highly variable between or even within strains. I investigated biochemical differences between high (KbHT) and low (KbLT) toxin producing cultures both derived from the Wilson strain, related to energy-dependent quenching (qE) by photosystem II, and the content of reduced thiols of the proteome. By characterizing the xanthophyll content of the two strains I was able to determine that KbLT performs qE inconsistently. To investigate the …

Synphilin-1 And Its Effects On Pathogenesis Of Parkinson’S Disease, Mirghani Mohamed

Honors Scholar Theses

Parkinson's Disease (PD) is a progressive neurodegenerative and movement disorder primarily caused by the degradation of dopaminergic neurons. Known markers of neurodegeneration in PD are Lewy Bodies, which are fibrillar aggregates that are found in the brains of PD patients. Lewy Bodies can accumulate from specific mutations in the SNCA gene that codes for alpha-synuclein, a protein enriched in presynaptic neurons. A mutated SNCA gene can cause conformational aggregates of alpha-synuclein to form toxic species mediating neuronal death. Research into alpha-synuclein has led to the discovery of a binding partner known as synphilin-1 that is also found in protein aggregates …

Lighting The Way: Recent Insights Into The Structure And Regulation Of Phototropin Blue Light Receptors, Jaynee E. Hart, Kevin H. Gardner

Publications and Research

The phototropins (phots) are light-activated kinases that are critical for plant physiology and the many diverse optogenetic tools that they have inspired. Phototropins combine two bluelight- sensing Light–Oxygen–Voltage (LOV) domains (LOV1 and LOV2) and a C-terminal serine/threonine kinase domain, using the LOV domains to control the catalytic activity of the kinase. While much is known about the structure and photochemistry of the light-perceiving LOV domains, particularly in how activation of the LOV2 domain triggers the unfolding of alpha helices that communicate the light signal to the kinase domain, many questions about phot structure and mechanism remain. Recent studies have made …

Effects Of Cocaine And/Or Heroin Use On Resting Cardiovascular Function, Shabber Syed Bs, Lina A. Shkokani Bs, Leslie H. Lundahl Phd, Renato S. Roxas Md, Philip D. Levy Md, Mark K. Greenwald Phd

Medical Student Research Symposium

Background: Regular cocaine and/or heroin use is associated with major health risks, especially cardiovascular disease (CVD), but confounded by other factors.

Objectives: We examined effects of chronic (years of regular use) and recent (past-month) use of cocaine and heroin, controlling for other factors, on resting cardiovascular function.

Methods: In a sample of cocaine and/or heroin users (N=292), we obtained data on demographics, body mass index (BMI), history of substance use, and electrocardiogram, heart rate (HR) and blood pressure (BP). Following bivariate correlations, three-block (1: demographics, BMI; 2: tobacco, alcohol, marijuana; 3: cocaine, heroin) regression analyses were …

Arginase 1 Insufficiency Precipitates Amyloid-Β Deposition And Hastens Behavioral Impairment In A Mouse Model Of Amyloidosis, Chao Ma, Jerry B. Hunt, Maj-Linda B. Selenica, Awa Sanneh, Leslie A. Sandusky-Beltran, Mallory Watler, Rana Daas, Andrii Kovalenko, Huimin Liang, Devon Placides, Chuanhai Cao, Xiaoyang Lin, Michael B. Orr, Bei Zhang, John C. Gensel, David J. Feola, Marcia N. Gordon, Dave Morgan, Paula C. Bickford, Daniel C. Lee

Sanders-Brown Center on Aging Faculty Publications

Alzheimer’s disease (AD) includes several hallmarks comprised of amyloid-β (Aβ) deposition, tau neuropathology, inflammation, and memory impairment. Brain metabolism becomes uncoupled due to aging and other AD risk factors, which ultimately lead to impaired protein clearance and aggregation. Increasing evidence indicates a role of arginine metabolism in AD, where arginases are key enzymes in neurons and glia capable of depleting arginine and producing ornithine and polyamines. However, currently, it remains unknown if the reduction of arginase 1 (Arg1) in myeloid cell impacts amyloidosis. Herein, we produced haploinsufficiency of Arg1 by the hemizygous deletion in myeloid cells using Arg1 …

Modulation Of Escherichia Coli Translation By The Specific Inactivation Of TrnaGly Under Oxidative Stress, Lorenzo Eugenio Leiva, Andrea Pincheira, Sara Elgamal, Sandra D. Kienast, Verónica Bravo, Johannes Leufken, Daniela Gutiérrez, Sebastian A. Leidel, Michael Ibba, Assaf Katz

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Bacterial oxidative stress responses are generally controlled by transcription factors that modulate the synthesis of RNAs with the aid of some sRNAs that control the stability, and in some cases the translation, of specific mRNAs. Here, we report that oxidative stress additionally leads to inactivation of tRNA^Gly in Escherichia coli, inducing a series of physiological changes. The observed inactivation of tRNA^Gly correlated with altered efficiency of translation of Gly codons, suggesting a possible mechanism of translational control of gene expression under oxidative stress. Changes in translation also depended on the availability of glycine, revealing a mechanism whereby bacteria …

Translational Regulation Of Environmental Adaptation In Bacteria, Rodney Tollerson Ii, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Bacteria must rapidly respond to both intracellular and environmental changes to survive. One critical mechanism to rapidly detect and adapt to changes in environmental conditions is control of gene expression at the level of protein synthesis. At each of the three major steps of translation—initiation, elongation, and termination—cells use stimuli to tune translation rate and cellular protein concentrations. For example, changes in nutrient concentrations in the cell can lead to translational responses involving mechanisms such as dynamic folding of riboswitches during translation initiation or the synthesis of alarmones, which drastically alter cell physiology. Moreover, the cell can fine-tune the levels …

Aminoacyl-Trna Synthetases, Miguel Angel Rubio Gomez, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The aminoacyl-tRNA synthetases are an essential and universally distributed family of enzymes that plays a critical role in protein synthesis, pairing tRNAs with their cognate amino acids for decoding mRNAs according to the genetic code. Synthetases help to ensure accurate translation of the genetic code by using both highly accurate cognate substrate recognition and stringent proofreading of noncognate products. While alterations in the quality control mechanisms of synthetases are generally detrimental to cellular viability, recent studies suggest that in some instances such changes facilitate adaption to stress conditions. Beyond their central role in translation, synthetases are also emerging as key …

Characterization Of A Split-Nluc Assay For Monitoring Changes In Alpha-Synuclein Solubility In Living Cells, Baolong Truong

Honors Theses

Alpha-synuclein is the primary constituent of Lewy Bodies, protein aggregates associated with Parkinson’s Disease, Dementia with Lewy Bodies, and Multiple Systems Dystrophy. Given the terminal nature of these synucleinopathies, the need for an assay that can report on alpha-synuclein aggregation levels in living systems is critical. Western blotting represents one potential approach to this problem; however, this technique can often be limited by selectivity of available antibodies and experimental reproducibility. Herein, we describe a novel luminescence-based assay capable of detecting alpha-synuclein solubility in bacterial cells. This platform can report on the influence of disease-relevant mutations and small molecules. Antibodies are …

Targeting Trna-Synthetase Interactions Towards Novel Therapeutic Discovery Against Eukaryotic Pathogens, Paul Kelly, Fatemeh Hadi-Nezhad, Dennis Y. Liu, Travis J. Lawrence, Roger G. Linington, Michael Ibba, David H. Ardell

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The development of chemotherapies against eukaryotic pathogens is especially challenging because of both the evolutionary conservation of drug targets between host and parasite, and the evolution of strain-dependent drug resistance. There is a strong need for new nontoxic drugs with broad-spectrum activity against trypanosome parasites such as Leishmania and Trypanosoma. A relatively untested approach is to target macromolecular interactions in parasites rather than small molecular interactions, under the hypothesis that the features specifying macromolecular interactions diverge more rapidly through coevolution. We computed tRNA Class-Informative Features in humans and independently in eight distinct clades of trypanosomes, identifying parasite-specific informative features, …

Alanyl-Trna Synthetase Quality Control Prevents Global Dysregulation Of The Escherichia Coli Proteome, Paul Kelly, Nicholas Backes, Kyle Mohler, Christopher Buser, Arundhati Kavoor, Jesse Rinehart, Gregory Phillips, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Mechanisms have evolved to prevent errors in replication, transcription, and translation of genetic material, with translational errors occurring most frequently. Errors in protein synthesis can occur at two steps, during tRNA aminoacylation and ribosome decoding. Recent advances in protein mass spectrometry have indicated that previous reports of translational errors have potentially underestimated the frequency of these events, but also that the majority of translational errors occur during ribosomal decoding, suggesting that aminoacylation errors are evolutionarily less tolerated. Despite that interpretation, there is evidence that some aminoacylation errors may be regulated, and thus provide a benefit to the cell, while others …

The Fitness Landscape Of The African Salmonella Typhimurium St313 Strain D23580 Reveals Unique Properties Of The Pbt1 Plasmid, Rocío Canals, Roy R. Chaudhuri, Rebecca E. Steiner, Siân V. Owen, Natalia Quinones-Olvera, Melita A. Gordon, Michael Baym, Michael Ibba, Jay C. D. Hinton

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We have used a transposon insertion sequencing (TIS) approach to establish the fitness landscape of the African Salmonella enterica serovar Typhimurium ST313 strain D23580, to complement our previous comparative genomic and functional transcriptomic studies. We used a genome-wide transposon library with insertions every 10 nucleotides to identify genes required for survival and growth in vitro and during infection of murine macrophages. The analysis revealed genomic regions important for fitness under two in vitro growth conditions. Overall, 724 coding genes were required for optimal growth in LB medium, and 851 coding genes were required for growth in SPI-2-inducing minimal medium. These …

Translational Control Of Antibiotic Resistance, Anne Witzky, Rodney Tollerson Ii, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Many antibiotics available in the clinic today directly inhibit bacterial translation. Despite the past success of such drugs, their efficacy is diminishing with the spread of antibiotic resistance. Through the use of ribosomal modifications, ribosomal protection proteins, translation elongation factors and mistranslation, many pathogens are able to establish resistance to common therapeutics. However, current efforts in drug discovery are focused on overcoming these obstacles through the modification or discovery of new treatment options. Here, we provide an overview for common mechanisms of resistance to translation-targeting drugs and summarize several important breakthroughs in recent drug development.

Alternative Nad(P)H Dehydrogenase And Alternative Oxidase: Proposed Physiological Roles In Animals, Allison Mcdonald, Dmytro V. Gospodaryov

Biology Faculty Publications

The electron transport systems in mitochondria of many organisms contain alternative respiratory enzymes distinct from those of the canonical respiratory system depicted in textbooks. Two of these enzymes, the alternative NADH dehydrogenase and the alternative oxidase, were of interest to a limited circle of researchers until they were envisioned as gene therapy tools for mitochondrial disease treatment. Recently, these enzymes were discovered in several animals. Here, we analyse the functioning of alternative NADH dehydrogenases and oxidases in different organisms. We propose that both enzymes ensure bioenergetic and metabolic flexibility during environmental transitions or other conditions which may compromise the operation …

Myocardial Ischemia Reperfusion Injury: Apoptotic, Inflammatory And Oxidative Stress Role Of Galectin-3, Suhail Al-Salam, Satwat Hashmi

Department of Biological & Biomedical Sciences

Background/aims: Myocardial reperfusion has the potential to salvage the ischemic myocardium after a period of coronary occlusion. Reperfusion, however, can cause a wide spectrum of deleterious effects. Galectin-3 (GAL-3), a beta galactoside binding lectin, is closely associated with myocardial infarction (MI), myocardial fibrosis and heart failure. In our study, we investigated its role in ischemia-reperfusion injuries (IR) as this phenomenon is extremely relevant to the early intervention after acute MI.
Methods: C57B6/J wild type (WT) mice and GAL-3 knockout (KO) mice were used for murine model of IR injury in the heart where a period of 30 minutes ischemia was …

Fars2 Mutations Presenting With Pure Spastic Paraplegia And Lesions Of The Dentate Nuclei, Supreet K. Sahai, Rebecca E. Steiner, Margaret G. Au, John M. Graham, Norikio Salamon, Michael Ibba, Tyler M. Pierson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Mutations in FARS2, the gene encoding the mitochondrial phenylalanine‐tRNA synthetase (mtPheRS), have been linked to a range of phenotypes including epileptic encephalopathy, developmental delay, and motor dysfunction. We report a 9‐year‐old boy with novel compound heterozygous variants of FARS2, presenting with a pure spastic paraplegia syndrome associated with bilateral signal abnormalities in the dentate nuclei. Exome sequencing identified a paternal nonsense variant (Q216X) lacking the catalytic core and anticodon‐binding regions, and a maternal missense variant (P136H) possessing partial enzymatic activity. This case confirms and expands the phenotype related to FARS mutations with regards to clinical presentation and neuroimaging findings.

Codon Usage Revisited: Lack Of Correlation Between Codon Usage And The Number Of Trna Genes In Enterobacteria, Joaquín Rojas, Gabriel Castillo, Lorenzo Eugenio Leiva, Sara Elgamal, Omar Orellana, Michael Ibba, Assaf Katz

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

It is widely believed that if a high number of genes are found for any tRNA in a rapidly replicating bacteria, then the cytoplasmic levels of that tRNA will be high and an open reading frame containing a higher frequency of the complementary codon will be translated faster. This idea is based on correlations between the number of tRNA genes, tRNA concentration and the frequency of codon usage observed in a limited number of strains as well as from the fact that artificially changing the number of tRNA genes alters translation efficiency and consequently the amount of properly folded protein …

Transcriptional Correlates Of Proximal-Distal Identify And Regeneration Timing In Axolotl Limbs, S. Randal Voss, David Murrugarra, Tyler B. Jensen, James R Monaghan

Neuroscience Faculty Publications

Cells within salamander limbs retain memories that inform the correct replacement of amputated tissues at different positions along the length of the arm, with proximal and distal amputations completing regeneration at similar times. We investigated the possibility that positional memory is associated with variation in transcript abundances along the proximal-distal limb axis. Transcripts were deeply sampled from Ambystoma mexicanum limbs at the time they were administered fore arm vs upper arm amputations, and at 19 post-amputation time points. After amputation and prior to regenerative outgrowth, genes typically expressed by differentiated muscle cells declined more rapidly in upper arms while cell …

Ef-P Post-Translational Modification Has Variable Impact On Polyproline Translation In Bacillus Subtilis, Anne Witzky, Katherine R. Hummels, Rodney Tollerson Ii, Andrei Rajkovic, Lisa A. Jones, Daniel B. Kearns, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Elongation factor P (EF-P) is a ubiquitous translation factor that facilitates translation of polyproline motifs. In order to perform this function, EF-P generally requires posttranslational modification (PTM) on a conserved residue. Although the position of the modification is highly conserved, the structure can vary widely between organisms. In Bacillus subtilis, EF-P is modified at Lys³² with a 5-aminopentanol moiety. Here, we use a forward genetic screen to identify genes involved in 5-aminopentanolylation. Tandem mass spectrometry analysis of the PTM mutant strains indicated that ynbB, gsaB, and ymfI are required for modification and that yaaO, yfkA, and …

Increased Liver Tumor Formation In Neutral Sphingomyelinase-2-Deficient Mice, Liansheng Zhong, Ji Na Kong, Michael B. Dinkins, Silvia Leanhart, Zhihui Zhu, Stefka D. Spassieva, Haiyan Qin, Hsuan-Pei Lin, Ahmed Elsherbini, Rebecca Wang, Xue Jiang, Mariana N. Nikolova‑Karakashian, Guanghu Wang, Erhard Bieberich

Physiology Faculty Publications

Sphingolipids are key signaling lipids in cancer. Genome-wide studies have identified neutral SMase-2 (nSMase2), an enzyme generating ceramide from SM, as a potential repressor for hepatocellular carcinoma. However, little is known about the sphingolipids regulated by nSMase2 and their roles in liver tumor development. We discovered growth of spontaneous liver tumors in 27.3% (9 of 33) of aged male nSMase2-deficient (fro/fro) mice. Lipidomics analysis showed a marked increase of SM in the tumor. Unexpectedly, tumor tissues presented with more than a 7-fold increase of C₁₆-ceramide, concurrent with upregulation of ceramide synthase 5. The fro/fro liver tumor, …

Mrub_1325, Mrub_1326, Mrub_1327, And Mrub_1328 Are Orthologs Of B_3454, B_3455, B_3457, B_3458, Respectively Found In Escherichia Coli Coding For A Branched Chain Amino Acid Atp Binding Cassette (Abc) Transporter System, Bennett Tomlin, Adam Buric, Dr. Lori Scott

Meiothermus ruber Genome Analysis Project

In this project we investigated the biological function of the genes Mrub_1325, Mrub_1326, Mrub_1327, and Mrub_1328 (KEGG map number 02010). We predict these genes encode components of a Branched Chain Amino Acid ATP Binding Cassette (ABC) transporter: 1) Mrub_1325 (DNA coordinates 1357399-1358130 on the reverse strand) encodes the ATP binding domain; 2) Mrub_1326 (DNA coordinates 1358127-1359899 on the reverse strand) encodes the ATP-binding domain and permease domain; 3) Mrub_1327 (DNA coordinates 1359899-1360930 on the reverse strand) encodes a permease domain; and 4)Mrub_1328 (DNA coordinates 1711022-1712185 on the reverse strand) encodes the substrate binding domain. This system is not predicted to …

Spontaneous Dna Damage To The Nuclear Genome Promotes Senescence, T Redox Imbalance And Aging, Andria R. Robinson, Matthew J. Yousefzadeh, Tania A. Rozgaja, Jin Wang, Xuesen Li, Jeremy S. Tilstra, Chelsea H. Feldman, Siobhan Q. Gregg, Caroline H. Johnson, Erin M. Skoda, Marie-Celine Frantz, Harris Bell-Temin, Hannah Pope-Varsalona, Aditi U. Gurkar, Luigi A. Nasto, Rena A.S. Robinson, Heike Fuhrmann-Stroissnigg, Jolanta Czerwinska, Sara J. Mcgowan, Nadiezhda Cantu-Madellin, Jamie B. Harris, Salony Maniar, Mark A. Ross, Christy E. Trussoni, Nicholas F. Larusso, Eugenia Cifuentes-Pagano, Patrick J. Pagano, Barbara Tudek, Nam V. Vo, Lora H. Rigatti, Patricia L. Opresko, Donna B. Stolz, Simon C. Watkins, Christin E. Burd, Claudette M. St, Croix, Gary Siuzdak, Nathan A. Yates, Paul D. Robbins, Yinsheng Wang, Peter Wipf, Eric E. Kelley, Laura J. Neidernhofer

Faculty & Staff Scholarship

Accumulation of senescent cells over time contributes to aging and age-related diseases. However, what drives senescence in vivo is not clear. Here we used a genetic approach to determine if spontaneous nuclear DNA damage is sufficient to initiate senescence in mammals. Ercc1-/Δ mice with reduced expression of ERCC1-XPF endonuclease have impaired capacity to repair the nuclear genome. Ercc1-/Δ mice accumulated spontaneous, oxidative DNA damage more rapidly than wild-type (WT) mice. As a consequence, senescent cells accumulated more rapidly in Ercc1-/Δ mice compared to repair-competent animals. However, the levels of DNA damage and senescent cells in Ercc1-/Δ mice never exceeded that …

Asymmetric Patterns Of Small Molecule Transport After Nanosecond And Microsecond Electropermeabilization, Esin B. Sözer, C. Florencia Pocetti, P. Thomas Vernier

Bioelectrics Publications

Imaging of fluorescent small molecule transport into electropermeabilized cells reveals polarized patterns of entry, which must reflect in some way the mechanisms of the migration of these molecules across the compromised membrane barrier. In some reports, transport occurs primarily across the areas of the membrane nearest the positive electrode (anode), but in others cathode-facing entry dominates. Here we compare YO-PRO-1, propidium, and calcein uptake into U-937 cells after nanosecond (6 ns) and microsecond (220 µs) electric pulse exposures. Each of the three dyes exhibits a different pattern. Calcein shows no preference for anode- or cathode-facing entry that is detectable with …

Translational Fidelity, Mistranslation, And The Cellular Responses To Stress, Kyle Mohler, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Faithful translation of mRNA into the corresponding polypeptide is a complex multistep process, requiring accurate amino acid selection, transfer RNA (tRNA) charging and mRNA decoding on the ribosome. Key players in this process are aminoacyl-tRNA synthetases (aaRSs), which not only catalyse the attachment of cognate amino acids to their respective tRNAs, but also selectively hydrolyse incorrectly activated non-cognate amino acids and/or misaminoacylated tRNAs. This aaRS proofreading provides quality control checkpoints that exclude non-cognate amino acids during translation, and in so doing helps to prevent the formation of an aberrant proteome. However, despite the intrinsic need for high accuracy during translation, …