Microbiology Commons^™

Quantifying Limits On Replication, Death, And Quiescence Of Mycobacterium Tuberculosis In Mice, Margaret M. Mcdaniel, Nitin Krishna, Winode G. Handagama, Shigetoshi Eda, Vitaly V. Ganusov

Microbiology Publications and Other Works

When an individual is exposed to Mycobacterium tuberculosis (Mtb) three outcomes are possible: bacterial clearance, active disease, or latent infection. It is generally believed that most individuals exposed to Mtb become latently infected and carry the mycobacteria for life. How Mtb is maintained during this latent infection remains largely unknown. During an Mtb infection in mice, there is a phase of rapid increase in bacterial numbers in the murine lungs within the first 3 weeks, and then bacterial numbers either stabilize or increase slowly over the period of many months. It has been debated whether the relatively constant numbers of …

Evidence For The Priming Effect In A Planktonic Estuarine Microbial Community, Andrew D. Steen, Lauren N.M. Quigley, Alison Buchan

Microbiology Publications and Other Works

The “priming effect,” in which addition of labile substances changes the remineralization rate of recalcitrant organic matter, has been intensively studied in soils, but is less well-documented in aquatic systems. We investigated the extent to which additions of nutrients or labile organic carbon could influence remineralization rates of 14C-labeled, microbially-degraded, phytoplankton-derived organic matter (OM) in microcosms inoculated with microbial communities drawn from Grove Creek Estuary in coastal Georgia, USA. We found that amendment with labile protein plus phosphorus increased remineralization rates of degraded, phytoplankton-derived OM by up to 100%, whereas acetate slightly decreased remineralization rates relative to an unamended control. …

Deep Groundwater And Potential Subsurface Habitats Beneath An Antarctic Dry Valley, Jill A. Mikucki, E. Auken, S. Tulaczyk, R. A. Virginia, C. Schamper, K. I. Sørensen, P. T. Doran, H. Dugan, N. Foley

Microbiology Publications and Other Works

The occurrence of groundwater in Antarctica, particularly in the ice-free regions and along the coastal margins is poorly understood. Here we use an airborne transient electromagnetic (AEM) sensor to produce extensive imagery of resistivity beneath Taylor Valley. Regional-scale zones of low subsurface resistivity were detected that are inconsistent with the high resistivity of glacier ice or dry permafrost in this region. We interpret these results as an indication that liquid, with sufficiently high solute content, exists at temperatures well below freezing and considered within the range suitable for microbial life. These inferred brines are widespread within permafrost and extend below …

Lessening Malaria Parasite Burden With Yogurt, Alivia M. Shasteen, Sarah W. Lebeis, Nathan Schmidt

Microbiology Publications and Other Works

The prevalence of malaria across the globe, particularly in countries with minimal health care availability, makes it a top priority for medical researchers. Dr. Nathan Schmidt’s lab discovered that mice from vendors from different geographical locations infected with malaria pathogens yielded significantly different parasite burdens. Researchers discovered that the reason behind the differences in parasite burden was a result of the different compositions of the gut microbiomes of the mice from the different vendors. The research in which I engaged involved manipulating the contents of the gut microbiome through yogurt in the hopes of lessening the parasite burden. Our results …

Transcriptomic Analysis Of Clostridium Thermocellum Populus Hydrolysate-Tolerant Mutant Strain Shows Increased Cellular Efficiency In Response To Populus Hydrolysate Compared To The Wild Type Strain, Jessica L. Linville, Miguel Rodriguez, Steve D. Brown, Jonathan R. Mielenz, Chris D. Cox

Microbiology Publications and Other Works

Background: The thermophilic, anaerobic bacterium, Clostridium thermocellum is a model organism for consolidated processing due to its efficient fermentation of cellulose. Constituents of dilute acid pretreatment hydrolysate are known to inhibit C. thermocellum and other microorganisms. To evaluate the biological impact of this type of hydrolysate, a transcriptomic analysis of growth in hydrolysate-containing medium was conducted on 17.5%?v/v Populus hydrolysate-tolerant mutant (PM) and wild type (WT) strains of C. thermocellum.ResultsIn two levels of Populus hydrolysate medium (0% and 10%?v/v), the PM showed both gene specific increases and decreases of gene expression compared to the wild-type strain. The PM had increased …

Seroprevalence And Genetic Characterization Of Toxoplasma Gondii In Three Species Of Pet Birds In China, Wei Cong, Meng Qing-Feng, Hui-Qun Song, Dong-Hui Zhou, Si-Yang Huang, Ai-Dong Qian, Chunlei Su, Xing-Quan Zhu

Microbiology Publications and Other Works

Background

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is one of the most common zoonosis worldwide, affecting a wide range of warm-blooded mammals and birds worldwide. However, no information on T. gondii infection in pet birds in China is available. Therefore, this study was performed to determine the prevalence of T. gondii infection in pet birds in Gansu province, China.

Methods

A total of 687 blood samples were collected from pet birds (Carduelis spinus, Alauda gulgula, Cocothraustes migratorlus) in three representative administrative regions in Gansu province, northwest China between August 2011 and September 2012 T. gondii antibodies …

Genome Sequence Of The Sulfitobacter Sp. Strain 2047-Infecting Lytic Phage Φcb2047-B, Nana Y.D. Ankrah, Charles R. Budinoff, William H. Wilson, Steven W. Wilhelm, Alison Buchan

Microbiology Publications and Other Works

We announce the complete genome sequence of a lytic podovirus, ΦCB2047-B, which infects the bacterium Sulfitobacter sp. strain 2047, a member of theRoseobacter clade. Genome analysis revealed ΦCB2047-B to be an N4-like phage, with its genome having high nucleotide similarity to other N4-like roseophage genomes.

Genome Sequences Of Two Temperate Phages, Φcb2047-A And Φcb2047-C, Infecting Sulfitobacter Sp. Strain 2047, Nana Y.D. Ankrah, Charles R. Budinoff, William H. Wilson, Steven W. Wilhelm, Alison Buchan

Microbiology Publications and Other Works

We announce the complete genome sequences of two temperate Podoviridae,Sulfitobacter phages ΦCB2047-A and ΦCB2047-C, which infect Sulfitobacter sp. strain 2047, a member of the Roseobacter clade. This is the first report of temperate podophage infecting members of the Sulfitobacter genus of theRoseobacter clade.

Acyl-Homoserine Lactone-Based Quorum Sensing In The Roseobacter Clade: Complex Cell-To-Cell Communication Controls Multiple Physiologies, W Nathan Cude, Alison Buchan

Microbiology Publications and Other Works

Bacteria have been widely reported to use quorum sensing (QS) systems, which employ small diffusible metabolites to coordinate gene expression in a population density dependent manner. In Proteobacteria, the most commonly described QS signaling molecules are N-acyl-homoserine lactones (AHLs). Recent studies suggest that members of the abundant marine Roseobacter lineage possess AHL-based QS systems and are environmentally relevant models for relating QS to ecological success. As reviewed here, these studies suggest that the roles of QS in roseobacters are varied and complex. An analysis of the 43 publically available Roseobacter genomes shows conservation of QS protein sequences and overall …

Genetic Characterization Of Toxoplasma Gondii From Qinghai Vole, Plateau Pika And Tibetan Ground-Tit On The Qinghai-Tibet Plateau, China, Xiao-Xuan Zhang, Zhong-Zi Lou, Si-Yang Huang, Dong-Hui Zhou, Wan-Zhong Jia, Chunlei Su, Xing-Quan Zhu

Microbiology Publications and Other Works

Background

The distribution of genetic diversity of Toxoplasma gondii in wildlife is of interest to understand the transmission of this parasite in the environment. Limited information on T. gondii genotypes has been reported in wildlife in China. The objective of this study was to carry out the genetic characterization of T. gondii isolates from wild animals on the Qinghai-Tibet Plateau.

Methods

Using PCR and multilocous polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technology, we detected genetic diversity of T. gondii isolates from Qinghai vole, Plateau pika and Tibetan ground-tit in these regions.

Results

In total, 183 brain tissues of different …

Genetic Characterization Of Toxoplasma Gondii From Pigs From Different Localities In China By Pcr-Rflp, Hai-Hai Jiang, Si-Yang Huang, Dong-Hui Zhou, Xiao-Xuan Zhang, Chunlei Su, Shun-Zhou Deng, Xing-Quan Zhu

Microbiology Publications and Other Works

Background

Toxoplasma gondii is a widely prevalent protozoan parasite that causes serious toxoplasmosis in humans and animals. The present study aimed to determine the genetic diversity of T. gondii isolates from pigs in Jiangxi, Sichuan, Guangdong Provinces and Chongqing Municipality in China using multilocous polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technology.

Methods

A total of 38 DNA samples were extracted from hilar lymph nodes of pigs with suspected toxoplasmosis, and were detected for the presence of T. gondii by semi-nested PCR of B1 gene. The positive DNA samples were typed at 11 genetic markers, including 10 nuclear loci, namely, …

Complete Genome Sequence Of Cyanobacterial Siphovirus Kbs2a, Alise J. Ponsero, Feng Chen, Jay T. Lennon, Steven W. Wilhelm

Microbiology Publications and Other Works

Abstract

We present the genome of a cyanosiphovirus (KBS2A) that infects a marine Synechococcus sp. (strain WH7803). Unique to this genome, relative to other sequenced cyanosiphoviruses, is the absence of elements associated with integration into the host chromosome, suggesting this virus may not be able to establish a lysogenic relationship. Go to:

GENOME ANNOUNCEMENT

As obligate parasites, viruses can regulate their host population dynamics but also influence the structure and productivity of microbial communities (1, 2). Synechococcus species are an abundant and ecologically important group of Cyanobacteria found in freshwater and marine ecosystems worldwide. Virus-cyanobacterium interactions may …

Insights Into Archaeal Evolution And Symbiosis From The Genomes Of A Nanoarchaeon And Its Inferred Crenarchaeal Host From Obsidian Pool, Yellowstone National Park, Mircea Podar, Kira S. Makarova, David E. Graham, Yuri I. Wolf, Eugene V. Koonin, Anna-Louise Reysenbach

Microbiology Publications and Other Works

Background

A single cultured marine organism, Nanoarchaeum equitans, represents the Nanoarchaeota branch of symbiotic Archaea, with a highly reduced genome and unusual features such as multiple split genes.

Results

The first terrestrial hyperthermophilic member of the Nanoarchaeota was collected from Obsidian Pool, a thermal feature in Yellowstone National Park, separated by single cell isolation, and sequenced together with its putative host, a Sulfolobales archaeon. Both the new Nanoarchaeota (Nst1) and N. equitans lack most biosynthetic capabilities, and phylogenetic analysis of ribosomal RNA and protein sequences indicates that the two form a deep-branching archaeal lineage. However, the Nst1 genome is …

Changes In The Proteomic Profiles Of Mouse Brain After Infection With Cyst-Forming Toxoplasma Gondii, Dong-Hui Zhou, Fu-Rong Zhao, Si-Yang Huang, Min-Jun Xu, Hui-Qun Song, Chunlei Su, Xing-Quan Zhu

Microbiology Publications and Other Works

Background

Toxoplasma gondii is an opportunistic pathogenic protozoan parasite, which infects approximately one third of the human population worldwide, causing opportunistic zoonotic toxoplasmosis. The predilection of T. gondii for the central nervous system (CNS) causes behavioral disorders and fatal necrotizing encephalitis and thus constitutes a major threat especially to AIDS patients.

Methods

In the present study, we explored the proteomic profiles of brain tissues of the specific pathogen-free (SPF) Kunming mice at 7 d, 14 d and 21 d after infection with cysts of the Toxoplasma gondii Prugniaud (PRU) strain (Genotype II), by two-dimensional gel electrophoresis (2-DE) combined with MALDI-TOF/TOF …

Dynamics Of Domain Coverage Of The Protein Sequence Universe, Bhanu Rekapalli, Kristin Wuichet, Gregory D. Peterson, Igor B. Zhulin

Microbiology Publications and Other Works

Background

The currently known protein sequence space consists of millions of sequences in public databases and is rapidly expanding. Assigning sequences to families leads to a better understanding of protein function and the nature of the protein universe. However, a large portion of the current protein space remains unassigned and is referred to as its “dark matter”.

Results

Here we suggest that true size of “dark matter” is much larger than stated by current definitions. We propose an approach to reducing the size of “dark matter” by identifying and subtracting regions in protein sequences that are not likely to contain …

Comparitive Metagenomics Of Toxic Freshwater Cyanobacteria Bloom Communities On Two Continents, Morgan M. Steffen, Zhou Li, T. Chad Effler, Loren J. Hauser, Gregory L. Boyer, Steven W. Wilhelm

Microbiology Publications and Other Works

Abstract

Toxic cyanobacterial blooms have persisted in freshwater systems around the world for centuries and appear to be globally increasing in frequency and severity. Toxins produced by bloom-associated cyanobacteria can have drastic impacts on the ecosystem and surrounding communities, and bloom biomass can disrupt aquatic food webs and act as a driver for hypoxia. Little is currently known regarding the genomic content of the Microcystis strains that form blooms or the companion heterotrophic community associated with bloom events. To address these issues, we examined the bloom-associated microbial communities in single samples from Lake Erie (North America), Lake Tai (Taihu, China), …

The Influence Of Sample Biases On Estimations Of Marine Microbial Diversity, Caroline Rempe, Charles R. Budinoff, T. C. Effler, Alison Buchan

Microbiology Publications and Other Works

Background

The Roseobacter clade is a widespread, metabolically versatile, and easily cultured lineage of marine microbes. Furthermore, cultured isolates are generally considered to be representative of the naturally occurring diversity in the environment. Roseobacter is thus considered an ideal clade for exploring and understanding microbial function in a representative model system. Nevertheless, recent studies question whether cultured strains are truly representative of natural populations. Support for one of these studies was based on the potentially biased samples of a Global Ocean Sampling (GOS) expedition [1]. The marine metagenomic studies of the GOS expeditions initially focused on microbes collected …

Bovine Serum Albumin Further Enhances The Effects Of Organic Solvents On Increased Yield Of Polymerase Chain Reaction Of Gc-Rich Templates, Eric M. Farell, Gladys Alexandre

Microbiology Publications and Other Works

Background

While being a standard powerful molecular biology technique, applications of the PCR to the amplification of high GC-rich DNA samples still present challenges which include limited yield and poor specificity of the reaction. Organic solvents, including DMSO and formamide, have been often employed as additives to increase the efficiency of amplification of high GC content (GC > 60%) DNA sequences. Bovine serum albumin (BSA) has been used as an additive in several applications, including restriction enzyme digestions as well as in PCR amplification of templates from environmental samples that contain potential inhibitors such as phenolic compounds.

Findings

Significant increase in …

Genomic Determinants Of Organohalide-Respiration In Geobacter Lovleyi, An Unusual Member Of The Geobacteraceae, Darlene D. Wager, Laura A. Hug, Janet K. Hatt, Melissa R. Spitzmiller, Elizabeth Padilla-Crespo, Kristi M. Ritalahti, Elizabeth A. Edwards, Konstantinos T. Konstantinidis, Frank E. Loffler

Microbiology Publications and Other Works

Background

Geobacter lovleyi is a unique member of the Geobacteraceae because strains of this species share the ability to couple tetrachloroethene (PCE) reductive dechlorination to cis-1,2-dichloroethene (cis-DCE) with energy conservation and growth (i.e., organohalide respiration). Strain SZ also reduces U(VI) to U(IV) and contributes to uranium immobilization, making G. lovleyi relevant for bioremediation at sites impacted with chlorinated ethenes and radionuclides. G. lovleyi is the only fully sequenced representative of this distinct Geobacter clade, and comparative genome analyses identified genetic elements associated with organohalide respiration and elucidated genome features that distinguish strain SZ from other members of …

Combined Inactivation Of The Clostridium Cellulolyticum Lactate And Malate Dehydrogenase Genes Substantially Increases Ethanol Yield From Cellulose And Switchgrass Fermentations, Yongchao Li, Timothy J. Tschaplinski, Nancy L. Engle, Choo Y. Hamilton, Miquel Rodriguez, James C. Liao, Christopher W. Schadt, Adam M. Guss, Yunfeng Yang, David E. Graham

Microbiology Publications and Other Works

Background

The model bacterium Clostridium cellulolyticum efficiently degrades crystalline cellulose and hemicellulose, using cellulosomes to degrade lignocellulosic biomass. Although it imports and ferments both pentose and hexose sugars to produce a mixture of ethanol, acetate, lactate, H₂ and CO₂, the proportion of ethanol is low, which impedes its use in consolidated bioprocessing for biofuels production. Therefore genetic engineering will likely be required to improve the ethanol yield. Plasmid transformation, random mutagenesis and heterologous expression systems have previously been developed for C. cellulolyticum, but targeted mutagenesis has not been reported for this organism, hindering genetic engineering.

Results …

Plasticity Of Total And Intracellular Phosphorus Quotas In Microcystis Aeruginosa Cultures And Lake Erie Algal Assemblages, Matthew A. Saxton, Robert J. Arnold, Richard A. Bourbonniere, Robert Michael L. Mckay, Steven W. Wilhelm

Microbiology Publications and Other Works

Blooms of the potentially toxic cyanobacterium Microcystis are common events globally, and as a result significant resources continue to be dedicated to monitoring and controlling these events. Recent studies have shown that a significant proportion of total cell-associated phosphorus (P) in marine phytoplankton can be surface adsorbed; as a result studies completed to date do not accurately report the P demands of these organisms. In this study we measure the total cell-associated and intracellular P as well as growth rates of two toxic strains of Microcystis aeruginosa Kütz grown under a range of P concentrations. The results show that the …

Detection Of Mycobacterium Ulcerans In The Environment Predicts Prevalence Of Buruli Ulcer In Benin, Heather R. Williamson, Mark E. Benbow, Lindsay P. Campbell, Christian R. Johnson, Ghislain Sopoh, Yves Barogui, Richard W. Merritt, Pamela L. C. Small

Microbiology Publications and Other Works

Background

Mycobacterium ulcerans is the causative agent of Buruli ulcer (BU). In West Africa there is an association between BU and residence in low-lying rural villages where aquatic sources are plentiful. Infection occurs through unknown environmental exposure; human-to-human infection is rare. Molecular evidence for M. ulcerans in environmental samples is well documented, but the association of M. ulcerans in the environment with Buruli ulcer has not been studied in West Africa in an area with accurate case data.

Methodology/Principal Finding

Environmental samples were collected from twenty-five villages in three communes of Benin. Sites sampled included 12 BU endemic villages within …

Next-Gen Sequencing Of Multi-Drug Resistant Acinetobacter Baumanii At Nashville General Hospital At Meharry, Leon Dent, Nahed Ismail, Steven Robinson, Gary Rogers, Siddharth Pratap, Dana Marshall

Microbiology Publications and Other Works

Background

Acinetobacter baumannii is a nonfermentative Gram-negative bacillus, which easily acquires antibiotic resistance determinants and causes life-threatening nosocomial infections [1]. Multi-drug resistant (MDR) strains are common therefore, empirical treatment choices are limited. More knowledge is needed regarding genetic diversity patterns and resistance phenotypes in a given clinical setting. Our goal is to identify the resistance genotypes of A. baumanii at Nashville General Hospital and correlate them with MDR phenotypes [1].

A Protocol For Enumeration Of Aquatic Viruses By Epifluorescence Microscopy Using Anodisc™ 13 Membranes, Charles Ryan Budinoff, Star N. Loar, Gary R. Lecleir, Steven W. Wilhelm, Alison Buchan

Microbiology Publications and Other Works

Abstract

Background

Epifluorescence microscopy is a common method used to enumerate virus-like particles (VLP) from environmental samples and relies on the use of filter membranes with pore sizes < 0.02 μm; the most commonly used protocols employ 25 mm Anodisc™ membranes with a built-in support ring. Other filters with small pore sizes exist, including the 13 mm Anodisc™ membranes without a support ring. However, the use of these membranes for viral enumeration has not been previously reported.

Results

Here we describe a modified protocol for 13 mm Anodisc membranes that uses a custom filter holder that can be readily constructed in individual investigators' laboratories from commercially available Swinnex^® filter holders. We compared VLP concentrations obtained from phage lysates and seawater samples using both Anodisc membranes, as well as Nuclepore™ small pore-size membranes (0.015 or 0.030 μm). The 13 mm Anodisc membranes gave comparable estimates of VLP abundance to …

A Protocol For Enumeration Of Aquatic Viruses By Epifluorescence Microscopy Using Anodisc™ 13 Membranes, Charlse R. Budinoff, Star N. Loar, Gary R. Lecleir, Steven W. Wilhelm, Alison Buchan

Microbiology Publications and Other Works

Background

Epifluorescence microscopy is a common method used to enumerate virus-like particles (VLP) from environmental samples and relies on the use of filter membranes with pore sizes < 0.02 μm; the most commonly used protocols employ 25 mm Anodisc™ membranes with a built-in support ring. Other filters with small pore sizes exist, including the 13 mm Anodisc™ membranes without a support ring. However, the use of these membranes for viral enumeration has not been previously reported.

Results

Here we describe a modified protocol for 13 mm Anodisc membranes that uses a custom filter holder that can be readily constructed in individual investigators' laboratories from commercially available Swinnex^® filter holders. We compared VLP concentrations obtained from phage lysates and seawater samples using both Anodisc membranes, as well as Nuclepore™ small pore-size membranes (0.015 or 0.030 μm). The 13 mm Anodisc membranes gave comparable estimates of VLP abundance to those …

So2426 Is A Positive Regulator Of Siderophore Expression In Shewanella Oneidensis Mr-1, Kristene L. Henne, Xiu-Feng Wan, Wei Wei, Dorothea K. Thompson

Microbiology Publications and Other Works

Background

The Shewanella oneidensis MR-1 genome encodes a predicted orphan DNA-binding response regulator, SO2426. Previous studies with a SO2426-deficient MR-1 strain suggested a putative functional role for SO2426 in the regulation of iron acquisition genes, in particular, the siderophore (hydroxamate) biosynthesis operon so3030-3031-3032. To further investigate the functional role of SO2426 in iron homeostasis, we employed computational strategies to identify putative gene targets of SO2426 regulation and biochemical approaches to validate the participation of SO2426 in the control of siderophore biosynthesis in S. oneidensis MR-1.

Results

In silico prediction analyses revealed a single 14-bp consensus …

Fnr (Etra) Acts As A Fine-Tuning Regulator Of Anaerobic Metabolism In Shewanella Oneidensis Mr-1, Claribel Cruz-Garcia, Alison E. Murray, Jorge Lm. Rodrigues, Jeffrey A. Gralnick, Lee A. Mccue, Margaret F. Romine, Frank E. Loffler, James M. Tiedje

Microbiology Publications and Other Works

Background

EtrA in Shewanella oneidensis MR-1, a model organism for study of adaptation to varied redox niches, shares 73.6% and 50.8% amino acid sequence identity with the oxygen-sensing regulators Fnr in E. coli and Anr in Pseudomonas aeruginosa, respectively; however, its regulatory role of anaerobic metabolism in Shewanella spp. is complex and not well understood.

Results

The expression of the nap genes, nrfA, cymA and hcp was significantly reduced in etrA deletion mutant EtrA7-1; however, limited anaerobic growth and nitrate reduction occurred, suggesting that multiple regulators control nitrate reduction in this strain. Dimethyl sulfoxide (DMSO) and fumarate reductase gene …

Dependence Of The Cyanobacterium Prochlorococcus On Hydrogen Peroxide Scavenging Microbes For Growth At The Ocean's Surface, J Jeffrey Morris, Zackary I. Johnson, Martin J. Szul, Martin Keller, Erik R. Zinser

Microbiology Publications and Other Works

The phytoplankton community in the oligotrophic open ocean is numerically dominated by the cyanobacterium Prochlorococcus, accounting for approximately half of all photosynthesis. In the illuminated euphotic zone where Prochlorococcus grows, reactive oxygen species are continuously generated via photochemical reactions with dissolved organic matter. However, Prochlorococcus genomes lack catalase and additional protective mechanisms common in other aerobes, and this genus is highly susceptible to oxidative damage from hydrogen peroxide (HOOH). In this study we showed that the extant microbial community plays a vital, previously unrecognized role in cross-protecting Prochlorococcus from oxidative damage in the surface mixed layer of the oligotrophic …

Niche Of Harmful Alga Aureococcus Anophagefferens Revealed Through Ecogenomics, Christopher Gobler, Dianna Berry, Sonya Dyhrman, Steven Wilhelm

Microbiology Publications and Other Works

Harmful algal blooms (HABs) cause significant economic and ecological damage worldwide. Despite considerable efforts, a comprehensive understanding of the factors that promote these blooms has been lacking, because the biochemical pathways that facilitate their dominance relative to other phytoplankton within specific environments have not been identified. Here, biogeochemical measurements showed that the harmful alga Aureococcus anophagefferens outcompeted co-occurring phytoplankton in estuaries with elevated levels of dissolved organic matter and turbidity and low levels of dissolved inorganic nitrogen. We subsequently sequenced the genome of A. anophagefferens and compared its gene complement with those of six competing phytoplankton species identified through metaproteomics. …

Killing Of Targets By Cd8+ T Cells In The Mouse Spleen Follows The Law Of Mass Action, Vitaly V. Ganusov, Daniel L. Barber, Rob J. De Boer

Microbiology Publications and Other Works

It has been difficult to correlate the quality of CD8 T cell responses with protection against viral infections. To investigate the relationship between efficacy and magnitude of T cell responses, we quantify the rate at which individual CD8 effector and memory T cells kill target cells in the mouse spleen. Using mathematical modeling, we analyze recent data on the loss of target cells pulsed with three different peptides from the mouse lymphocytic choriomeningitis virus (LCMV) in mouse spleens with varying numbers of epitope-specific CD8 T cells. We find that the killing of targets follows the law of mass-action, i.e., the …