Biotechnology Commons^™

Book Review Of Dane Kennedy, The Last Blank Spaces: Exploring Africa And Australia, Adrian S. Wisnicki

Department of Biochemistry: Faculty Publications

Mid-nineteenth-century British exploration, particularly the stories of the “heroic” individuals who carried out this exploration, remains a topic of worldwide interest, as most recently evidenced by the many events in Britain and Africa celebrating the 2013 bicentenary of David Livingstone’s birth. Dane Kennedy’s intriguing study takes issue with such readings of the historical record by foregrounding an epistemological tension that lies at the heart of nineteenthcentury British exploration discourse and practice. The book examines the collision—as it played out in the exploration of African and Australia—between metropolitan scientific protocols and non-Western quotidian realities. Nineteenth-century explorers, argues Kennedy, left home with …

Arabidopsis Cuticular Wax Biosynthesis Is Negatively Regulated By The Dewax Gene Encoding An Ap2/Erf-Type Transcription Factor, Young Sam Go, Hyojin Kim, Hae Jin Kim, Mi Chung Suh

Department of Biochemistry: Faculty Publications

The aerial parts of plants are protected from desiccation and other stress by surface cuticular waxes. The total cuticular wax loads and the expression of wax biosynthetic genes are significantly downregulated in Arabidopsis thaliana under dark conditions. We isolated Decrease Wax Biosynthesis (DEWAX), which encodes an AP2/ERF-type transcription factor that is preferentially expressed in the epidermis and induced by darkness. Disruption of DEWAX leads to an increase in total leaf and stem wax loads, and the excess wax phenotype of dewax was restored to wild type levels in complementation lines. Moreover, overexpression of DEWAX resulted in a reduction …

Stress Adaptation In A Pathogenic Fungus, Alistair J. P. Brown, Susan Budge, Despoina Kaloriti, Anna Tillmann, Mette D. Jacobsen, Zhikang Yin, Iuliana V. Ene, Iryna Bohovych, Doblin Sandai, Stavroula Kastora, Joanna Potrykus, Elizabeth R. Ballou, Delma S. Childers, Shahida Shahana, Michelle D. Leach

Department of Biochemistry: Faculty Publications

Candida albicans is a major fungal pathogen of humans. This yeast is carried by many individuals as a harmless commensal, but when immune defences are perturbed it causes mucosal infections (thrush). Additionally, when the immune system becomes severely compromised, C. albicans often causes life-threatening systemic infections. A battery of virulence factors and fitness attributes promote the pathogenicity of C. albicans. Fitness attributes include robust responses to local environmental stresses, the inactivation of which attenuates virulence. Stress signalling pathways in C. albicans include evolutionarily conserved modules. However, there has been rewiring of some stress regulatory circuitry such that the roles of …

Stress-Triggered Activation Of The Metalloprotease Oma1 Involves Its C-Terminal Region And Is Important For Mitochondrial Stress Protection In Yeast, Iryna Bohovych, Garrett Donaldson, Sara Christianson, Nataliya Zahayko, Oleh Khalimonchuk

Department of Biochemistry: Faculty Publications

Background: Oma1 is a conserved membrane-bound protease that forms a high molecular mass complex.

Results: Oma1 activity is induced by stress stimuli and required for survival. The activation is linked to changes in Oma1 oligomer stability and involves its C-terminal region.

Conclusion: Oma1 function is activated by mitochondrial stress and is important for stress tolerance.

Significance: Novel insights into Oma1 function and a potential stress activation mechanism are provided.

Proline Biosynthesis Is Required For Endoplasmic Reticulum Stress Tolerance In Saccharomyces Cerevisiae, Xinwen Liang, M. B. Dickman, Donald F. Becker

Department of Biochemistry: Faculty Publications

Background: Proline is an important amino acid for stress resistance in different organisms.

Results: Depletion of proline biosynthesis disrupts redox homeostasis and increases sensitivity to endoplasmic reticulum (ER) stress in yeast.

Conclusion: Proline biosynthesis is critical for maintaining the intracellular redox environment and the UPR during ER stress.

Significance: Proline metabolism is shown to have an important role in ER stress tolerance that was previously unknown.

Protein/Protein Interactions In The Mammalian Heme Degradation Pathway Heme Oxygenase-2, Cytochrome P450 Reductase, And Biliverdin Reductase, Andrea L. M. Spencer, Ireena Bagai, Donald F. Becker, Erik R. P. Zuiderweg, Stephen W. Ragsdale

Department of Biochemistry: Faculty Publications

Background: Heme oxygenase, cytochrome P450 reductase, and biliverdin reductase are the key enzymes in heme degradation.

Results: Specific electrostatic and hydrophobic interactions form the binding interface between heme oxygenase and cytochrome P450 reductase. Conclusion: Heme oxygenase binds cytochrome P450 reductase dynamically and biliverdin reductase very weakly.

Significance: Characterizing interactions among proteins involved in heme degradation are crucial to understanding heme homeostasis.

Plant Acyl-Coa:Lysophosphatidylcholine Acyltransferases (Lpcats) Have Different Specificities In Their Forward And Reverse Reactions, Ida Lager, Jenny Lindberg Yilmaz, Xue-Rong Zhou, Katarzyna Jasieniecka, Michael Kazachkov, Peng Wang, Jitao Zou, Randall Weselake, Mark A. Smith, Shen Bayon, John M. Dyer, Jay Shockey, Ernst Heinz, Allan Green, Antoni Banas, Sten Stymne

Department of Biochemistry: Faculty Publications

Background: Acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT) enzymes have central roles in acyl editing of phosphatidylcholine.

Results: Plant LPCATs were expressed in yeast and biochemically characterized.

Conclusion: LPCATs can edit acyl composition of phosphatidylcholine through their combined forward and reverse reactions.

Significance: Plant LPCATs play a role in editing both sn-positions of PC and remove ricinoleic acid with high selectivity from this lipid.

Emerging Regulatory Paradigms In Glutathione Metabolism, Yilin Liu, Annastasia S. Hyde, Melanie A. Simpson, Joseph J. Barycki

Department of Biochemistry: Faculty Publications

One of the hallmarks of cancer is the ability to generate and withstand unusual levels of oxidative stress. In part, this property of tumor cells is conferred by elevation of the cellular redox buffer glutathione. Though enzymes of the glutathione synthesis and salvage pathways have been characterized for several decades, we still lack a comprehensive understanding of their independent and coordinate regulatory mechanisms. Recent studies have further revealed that overall central metabolic pathways are frequently altered in various tumor types, resulting in significant increases in biosynthetic capacity, and feeding into glutathione synthesis. In this review, we will discuss the enzymes …

Emerging Roles For Hyaluronidase In Cancer Metastasis And Therapy, Caitlin O. Mcatee, Joseph J. Barycki, Melanie A. Simpson

Department of Biochemistry: Faculty Publications

Hyaluronidases are a family of five human enzymes that have been differentially implicated in the progression of many solid tumor types, both clinically and in functional studies. Advances in the past five years have clarified many apparent contradictions, (1) by demonstrating that specific hyaluronidases have alternative substrates to hyaluronan (HA) or do not exhibit any enzymatic activity, (2) that high molecular weight HA polymers elicit signaling effects that are opposite those of the hyaluronidase-digested HA oligomers, and (3) that it is actually the combined overexpression of HA synthesizing enzymes with hyaluronidases that confers tumorigenic potential. This review examines the literature …

Mechanisms Underlying The Exquisite Sensitivity Of Candida Albicans To Combinatorial Cationic And Oxidative Stress That Enhances The Potent Fungicidal Activity Of Phagocytes, Despoina Kaloriti, Mette Jacobsen, Zhikang Yin, Miranda Patterson, Anna Tillmann, Deborah A. Smith, Emily Cook, Tao You, Melissa J. Grimm, Iryna Bohovych, Celso Grebogi, Brahm H. Segal, Neil A.R. Gow, Ken Haynes, Janet Quinn, Alistair J.P. Brown

Department of Biochemistry: Faculty Publications

Immune cells exploit reactive oxygen species (ROS) and cationic fluxes to kill microbial pathogens, such as the fungus

Candida albicans. Yet, C. albicans is resistant to these stresses in vitro. Therefore, what accounts for the potent antifungal activity

of neutrophils? We show that simultaneous exposure to oxidative and cationic stresses is much more potent than the individual

stresses themselves and that this combinatorial stress kills C. albicans synergistically in vitro.We also show that the high

fungicidal activity of human neutrophils is dependent on the combinatorial effects of the oxidative burst and cationic fluxes, as

their pharmacological attenuation with …

New Clox Systems For Rapid And Efficient Gene Disruption In Candida Albicans, Shahida Shahana, Delma S. Childers, Elizabeth R. Ballou, Iryna Bohovych, Frank C. Odds, Neil A.R. Gow, Alistair J.P. Brown

Department of Biochemistry: Faculty Publications

Precise genome modification is essential for the molecular dissection of Candida albicans, and is yielding invaluable information about the roles of specific gene functions in this major fungal pathogen of humans. C. albicans is naturally diploid, unable to undergo meiosis, and utilizes a non-canonical genetic code. Hence, specialized tools have had to be developed for gene disruption in C. albicans that permit the deletion of both target alleles, and in some cases, the recycling of the Candida-specific selectable markers. Previously, we developed a tool based on the Cre recombinase, which recycles markers in C. albicans with 90–100% efficiency via …

Saturated Free Fatty Acids Induce Cholangiocyte Lipoapoptosis, Sathish Kumar Natarajan, Sally A. Ingham, Ashley M. Mohr, Cody J. Wehrkamp, Anuttoma Ray, Sohini Roy, Sophie C. Cazanave, Mary Anne Phillippi, Justin L. Mott

Department of Biochemistry: Faculty Publications

Recent studies have identified a cholestatic variant of nonalcoholic fatty liver disease (NAFLD) with portal inflammation and ductular reaction. Based on reports of biliary damage, as well as increased circulating free fatty acids (FFAs) in NAFLD, we hypothesized the involvement of cholangiocyte lipoapoptosis as a mechanism of cellular injury. Here, we demonstrate that the saturated FFAs palmitate and stearate induced robust and rapid cell death in cholangiocytes. Palmitate and stearate induced cholangiocyte lipoapoptosis in a concentration-dependent manner in multiple cholangiocyte-derived cell lines. The mechanism of lipoapoptosis relied on the activation of caspase 3/7 activity. There was also a significant up-regulation …

Xiap Antagonist Embelin Inhibited Proliferation Of Cholangiocarcinoma Cells, Cody J. Wehrkamp, Ashley R. Gutwein, Sathish Kumar Natarajan, Mary Anne Phillippi, Justin L. Mott

Department of Biochemistry: Faculty Publications

Cholangiocarcinoma cells are dependent on antiapoptotic signaling for survival and resistance to death stimuli. Recent mechanistic studies have revealed that increased cellular expression of the E3 ubiquitin-protein ligase X-linked inhibitor of apoptosis (XIAP) impairs TRAIL- and chemotherapy-induced cytotoxicity, promoting survival of cholangiocarcinoma cells. This study was undertaken to determine if pharmacologic antagonism of XIAP protein was sufficient to sensitize cholangiocarcinoma cells to cell death. We employed malignant cholangiocarcinoma cell lines and used embelin to antagonize XIAP protein. Embelin treatment resulted in decreased XIAP protein levels by 8 hours of treatment with maximal effect at 16 hours in KMCH and Mz-ChA-1 …

Oxidative Stress, Redox Signaling, And Autophagy: Cell Death Versus Survival, Juliana Navarro-Yepes, Michaela Burns, Anandhan Annadurai, Oleh Khalimonchuk, Luz Maria Del Razo, Betzabet Quintanilla-Vega, Aglaia Pappa, Mihalis I. Panayiotidis, Rodrigo Franco

Department of Biochemistry: Faculty Publications

Significance: The molecular machinery regulating autophagy has started becoming elucidated, and a number of studies have undertaken the task to determine the role of autophagy in cell fate determination within the context of human disease progression. Oxidative stress and redox signaling are also largely involved in the etiology of human diseases, where both survival and cell death signaling cascades have been reported to be modulated by reactive oxygen species (ROS) and reactive nitrogen species (RNS). Recent Advances: To date, there is a good understanding of the signaling events regulating autophagy, as well as the signaling processes by which alterations in …

Kinetic And Structural Characterization Of Tunnel-Perturbing Mutants In Bradyrhizobium Japonicum Proline Utilization A, Benjamin W. Arentson, Min Luo, Travis A. Pemberton, John J. Tanner, Donald F. Becker

Department of Biochemistry: Faculty Publications

Proline utilization A from Bradyrhizobium japonicum (BjPutA) is a bifunctional flavoenzyme that catalyzes the oxidation of proline to glutamate using fused proline dehydrogenase (PRODH) and Δ¹-pyrroline-5-carboxylate dehydrogenase (P5CDH) domains. Recent crystal structures and kinetic data suggest an intramolecular channel connects the two active sites, promoting substrate channeling of the intermediate Δ¹-pyrroline-5-carboxylate/glutamate-γ-semialdehyde (P5C/GSA). In this work, the structure of the channel was explored by inserting large side chain residues at four positions along the channel in BjPutA. Kinetic analysis of the different mutants revealed replacement of D779 with Tyr (D779Y) or Trp (D779W) significantly decreased the overall …

Evidence That The C‑Terminal Domain Of A Type B Puta Protein Contributes To Aldehyde Dehydrogenase Activity And Substrate Channeling, Min Luo, Shelbi Christgen, Nikhilesh Sanyal, Benjamin W. Arentson, Donald F. Becker, John J. Tanner

Department of Biochemistry: Faculty Publications

Proline utilization A (PutA) is a bifunctional enzyme that catalyzes the oxidation of proline to glutamate. Structures of type A PutAs have revealed the catalytic core consisting of proline dehydrogenase (PRODH) and Δ1- pyrroline-5-carboxylate dehydrogenase (P5CDH) modules connected by a substrate-channeling tunnel. Type B PutAs also have a C-terminal domain of unknown function (CTDUF) that is absent in type A PutAs. Small-angle X-ray scattering (SAXS), mutagenesis, and kinetics are used to determine the contributions of this domain to PutA structure and function. The 1127-residue Rhodobacter capsulatus PutA (RcPutA) is used as a representative CTDUF-containing type B PutA. The reaction progress …

Homogeneous Low-Molecular-Weight Heparins With Reversible Anticoagulant Activity, Yongmei Xu, Chao Cai, Kasemsiri Chandarajoti, Po-Hung Hsieh, Lingyun Li, Truong Q. Pham, Erica M. Sparkenbaugh, Juzheng Sheng, Nigel S. Key, Rafal Pawlinski, Edward N. Harris, Robert J. Linhardt, Jian Liu

Department of Biochemistry: Faculty Publications

Low-molecular-weight heparins (LMWHs) are carbohydrate-based anticoagulants clinically used to treat thrombotic disorders, but impurities, structural heterogeneity or functional irreversibility can limit treatment options. We report a series of synthetic LMWHs prepared by cost-effective chemoenzymatic methods. The high activity of one defined synthetic LMWH against human factor Xa (FXa) was reversible in vitro and in vivo using protamine, demonstrating that synthetically accessible constructs can have a critical role in the next generation of LMWHs.

Pharmacological Correction Of Obesity-Induced Autophagy Arrest Using Calcium Channel Blockers, Hwan-Woo Park, Haeli Park, Ian A. Semple, Insook Jang, Seung-Hyun Ro, Myungjin Kim, Victor A. Cazares, Edward L. Stuenkel, Jung-Jae Kim, Jeong Sig Kim, Jun Hee Lee

Department of Biochemistry: Faculty Publications

Autophagy deregulation during obesity contributes to the pathogenesis of diverse metabolic disorders. However, without understanding the molecular mechanism of obesity interference in autophagy, development of therapeutic strategies for correcting such defects in obese individuals is challenging. Here we show that a chronic increase of the cytosolic calcium concentration in hepatocytes during obesity and lipotoxicity attenuates autophagic flux by preventing the fusion between autophagosomes and lysosomes. As a pharmacological approach to restore cytosolic calcium homeostasis in vivo, we administered the clinically approved calcium channel blocker verapamil to obese mice. Such treatment successfully increases autophagosome–lysosome fusion in liver, preventing accumulation of …

Hepatoprotective Role Of Sestrin2 Against Chronic Er Stress, Hwan-Woo Park, Haeli Park, Seung-Hyun Ro, Insook Jang, Ian A. Semple, David N. Kim, Myungjin Kim, Myeongjin Nam, Deqiang Zhang, Lei Yin, Jun Hee Lee

Department of Biochemistry: Faculty Publications

Upon prolonged endoplasmic reticulum (ER) stress, cells attenuate protein translation to prevent accumulation of unfolded proteins. Here we show that Sestrin2 is critical for this process. Sestrin2 expression is induced by an ER stress-activated transcription factor CCAATenhancer- binding protein beta (c/EBPβ). Once induced, Sestrin2 halts protein synthesis by inhibiting mammalian target of rapamycin complex 1 (mTORC1). As Sestrin2-deficient cells continue to translate a large amount of proteins during ER stress, they are highly susceptible to ER stress-associated cell death. Accordingly, dietary or genetically induced obesity, which does not lead to any pathological indication other than simple fat accumulation in the …

Estimating The Frequency Of Cry1f Resistance In Field Populations Of The European Corn Borer (Lepidoptera: Crambidae), Blair D. Siegfried, Murugesan Rangasamy, Haichuan Wang, Terence A. Spencer, Chirakkal V. Haridas, Brigitte Tenhumberg, Douglas V. Sumerford, Nicholas P. Storer

School of Biological Sciences: Faculty Publications

Background: Transgenic corn hybrids that express toxins from Bacillus thuringiensis (Bt) have suppressed European corn borer populations and reduced the pest status of this insect throughout much of the US corn belt. A major assumption of the high-dose/refuge strategy proposed for insect resistance management and Bt corn is that the frequency of resistance alleles is low so that resistant pests surviving exposure to Bt corn will be rare. Results: The frequency of resistance to the Cry1F Bt toxin was estimated using two different screening tools and compared with annual susceptibility monitoring based on diagnostic bioassays and LC_{50 …}

Physiological And Transcriptional Memory In Guard Cells During Repetitive Dehydration Stress, Laetitia Virlouvet, Michael E. Fromm

Nebraska Center for Biotechnology: Faculty and Staff Publications

Arabidopsis plants subjected to a daily dehydration stress and watered recovery cycle display physiological and transcriptional stress memory. Previously stressed plants have stomatal apertures that remain partially closed during a watered recovery period, facilitating reduced transpiration during a subsequent dehydration stress. Guard cells (GCs) display transcriptional memory that is similar to that in leaf tissues for some genes, but display GC-specific transcriptional memory for other genes. The rate-limiting abscisic acid (ABA) biosynthetic genes NINE-CIS-EPOXYCAROTENOID DIOXYGENASE 3 (NCED3) and ALDEHYDE OXIDASE 3 (AAO3) are expressed at much higher levels in GCs, particularly during the watered recovery interval, relative to their low …

The Pseudomonas Syringae Type Iii Effector Hopd1 Suppresses Effector-Triggered Immunity, Localizes To The Endoplasmic Reticulum, And Targets The Arabidopsis Transcription Factor Ntl9, Anna Block, Tania Y. Toruno, Christian G. Elowsky, Chi Zhang, Jens Steinbrenner, Jim Beynon, James R. Alfano

Nebraska Center for Biotechnology: Faculty and Staff Publications

Pseudomonas syringae type III effectors are known to suppress plant immunity to promote bacterial virulence. However, the activities and targets of these effectors are not well understood. We used genetic, molecular, and cell biology methods to characterize the activities, localization, and target of the HopD1 type III effector in Arabidopsis. HopD1 contributes to P. syringae virulence in Arabidopsis and reduces effector-triggered immunity (ETI) responses but not pathogen-associated molecular pattern-triggered immunity (PTI) responses. Plants expressing HopD1 supported increased growth of ETI-inducing P. syringae strains compared with wild-type Arabidopsis. We show that HopD1 interacts with the membrane-tethered Arabidopsis transcription factor NTL9 and …

Near-Infrared Surface-Enhanced Fluorescence Using Silver Nanoparticles In Solution, Michael D. Furtaw

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Fluorescence spectroscopy is a widely used detection technology in many research and clinical assays. Further improvement to assay sensitivity may enable earlier diagnosis of disease, novel biomarker discovery, and ultimately, improved outcomes of clinical care along with reduction in costs. Near-infrared, surface-enhanced fluorescence (NIR-SEF) is a promising approach to improve assay sensitivity via simultaneous increase in signal with a reduction in background. This dissertation describes research conducted with the overall goal to determine the extent to which fluorescence in solution may be enhanced by altering specific variables involved in the formation of plasmonactive nanostructures of dye-labeled protein and silver nanoparticles …

Cytochrome B5 Reductase Encoded By Cbr1 Is Essential For A Functional Male Gametophyte In Arabidopsis, Laura L. Wayne, James G. Wallis, Rajesh Kumar, Jennifer E. Markham, John Browse

Department of Biochemistry: Faculty Publications

In all eukaryotes, NADH:cytochrome b5 reductase provides electrons, via cytochrome b5, for a range of biochemical reactions in cellular metabolism, including for fatty acid desaturation in the endoplasmic reticulum. Studies in mammals, yeast, and in vitro plant systems have shown that cytochrome b5 can, at least in some circumstances, also accept electrons from NADPH:cytochrome P450 reductase, potentially allowing for redundancy in reductase function. Here, we report characterization of three T-DNA insertional mutants of the gene encoding cytochrome b5 reductase in Arabidopsis thaliana, CBR1. The progeny of plants heterozygous for the cbr1-2 allele segregated 6% homozygous mutants, while cbr1-3 and cbr1-4 …

A Morphological Analysis Of A Hybrid Swarm Of Native Ulmus Rubra And Introduced U. Pumila (Ulmaceae) In Southeastern Nebraska, Christian Elowsky, Ingrid E. Jordon-Thaden, Robert B. Kaul

Nebraska Center for Biotechnology: Faculty and Staff Publications

The parental species and hybrid swarm of native Ulmus rubra Muhl. and the introduced, naturalized and weedy U. pumila L. were investigated in a 65-km transect in Lancaster, Saunders, and Butler counties in Nebraska. Thirty-two trees of U. rubra, 32 of U. pumila, and 50 of the hybrid swarm were sampled for leaves and buds and subsampled for flowers and fruits. Leaves were measured for petiole length, blade length, width, primary and secondary teeth per cm, number of secondary teeth per primary tooth, and texture. Buds were scored for color and distribution of trichomes. Flowers were sampled for stamen counts …

Diversity Of Plant Methionine Sulfoxide Reductases B And Evolution Of A Form Specific For Free Methionine Sulfoxide, Dung Tien Le, Lionel Tarrago, Yasuko Watanabe, Alaattin Kaya, Byung Cheon Lee, Uyen Tran, Rie Nishiyama, Dmitri E. Fomenko, Vadim N. Gladyshev, Lam-Son Phan Tran

Department of Biochemistry: Faculty Publications

Methionine can be reversibly oxidized to methionine sulfoxide (MetO) under physiological conditions. Organisms evolved two distinct methionine sulfoxide reductase families (MSRA & MSRB) to repair oxidized methionine residues. We found that 5 MSRB genes exist in the soybean genome, including GmMSRB1 and two segmentally duplicated gene pairs (GmMSRB2 and GmMSRB5, GmMSRB3 and GmMSRB4). GmMSRB2 and GmMSRB4 proteins showed MSRB activity toward protein-based MetO with either DTT or thioredoxin (TRX) as reductants, whereas GmMSRB1 was active only with DTT. GmMSRB2 had a typical MSRB mechanism with Cys121 and Cys 68 as catalytic and resolving residues, respectively. Surprisingly, this enzyme also possessed …

Biomass Gasification: An Alternative Solution To Animal Waste Management, Hanjing Wu

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

The overall goal of this research was to evaluate gasification of animal waste as an alternative manure management strategy, from the standpoints of syngas production and biochar application.

To meet the overall objective, the thermogravimetric characteristics of dairy manure, as a thermochemical conversion feedstock, were studied firstly. Then, gasification technology was applied to dairy manure and feedlot manure using a fluidized-bed laboratory-scale gasifier. In addition, biochar derived from the feedlot manure was examined for its effects on nutrient leaching as a soil amendment. Finally, a life cycle assessment was conducted to evaluate greenhouse gas emissions of two feedlot manure management …

A Cell Simulator Platform: The Cell Collective, Tomáš Helikar, B. Kowal, J. A. Rogers

Department of Biochemistry: Faculty Publications

Diseases are often a result of multiple malfunctions in complex, nonlinear biological/biochemical networks. As such, these processes are far more complicated to understand because they tend to give rise to functions that are emergent in nature, i.e., higher-level (mal)functions that are more than the sum of their parts. Systems biology provides a new approach to understanding biological systems and diseases from a holistic perspective.

Proline Mechanisms Of Stress Survival, Xinwen Liang, Lu Zhang, Sathish Kumar Natarajan, Donald F. Becker

Department of Biochemistry: Faculty Publications

Significance: The imino acid proline is utilized by different organisms to offset cellular imbalances caused by environmental stress. The wide use in nature of proline as a stress adaptor molecule indicates that proline has a fundamental biological role in stress response. Understanding the mechanisms by which proline enhances abiotic/biotic stress response will facilitate agricultural crop research and improve human health. Recent Advances: It is now recognized that proline metabolism propels cellular signaling processes that promote cellular apoptosis or survival. Studies have shown that proline metabolism influences signaling pathways by increasing reactive oxygen species (ROS) formation in the mitochondria …

Comparative Metabolic Profiling Of Haberlea Rhodopensis, Thellungiella Halophyla, And Arabidopsis Thaliana Exposed To Low Temperature, Maria Benina, Toshihiro Obata, Nikolay Mehterov, Ivan Ivanov, Veselin Petrov, Valentina Toneva, Alisdair R. Fernie, Tsanko S. Gechev

Department of Biochemistry: Faculty Publications

Haberlea rhodopensis is a resurrection species with extreme resistance to drought stress and desiccation but also with ability to withstand low temperatures and freezing stress. In order to identify biochemical strategies which contribute to Haberlea's remarkable stress tolerance, the metabolic reconfiguration of H. rhodopensis during low temperature (4^◦C) and subsequent return to optimal temperatures (21^◦C) was investigated and compared with that of the stress tolerant Thellungiella halophyla and the stress sensitive Arabidopsis thaliana. Metabolic analysis by GC-MS revealed intrinsic differences in the metabolite levels of the three species even at 21^◦C. H. rhodopensis …