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2012

Biology

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Articles 61 - 73 of 73

Full-Text Articles in Life Sciences

Mind The Gap: A Comparative Study Of Migratory Behavior In Social Amoebae, Owen M. Gilbert, Jennie J. Kuzdzal-Fick, David C. Queller, Joan E. Strassmann Jan 2012

Mind The Gap: A Comparative Study Of Migratory Behavior In Social Amoebae, Owen M. Gilbert, Jennie J. Kuzdzal-Fick, David C. Queller, Joan E. Strassmann

Biology Faculty Publications & Presentations

Social amoebae aggregate to form a multicellular slug that migrates some distance. Most species produce a stalk during migration, but some do not. We show that Dictyostelium giganteum, a species that produces stalk during migration, is able to traverse small gaps and utilize bacterial resources following gap traversal by shedding live cells. In contrast, we found that Dictyostelium discoideum, a species that does not produce stalk during migration, can traverse gaps only when in the presence of other species’ stalks or other thin filaments. These findings suggest that production of stalk during migration allows traversal of gaps that commonly occurs …


Structured Growth And Genetic Drift Raise Relatedness In The Social Amoeba Dictyostelium Discoideum, Neil J. Buttery, Chandra N. Jack, Boahemaa Adu-Oppong, Kate T. Snyder, Christoper R L Thompson, David C. Queller, Joan E. Strassmann Jan 2012

Structured Growth And Genetic Drift Raise Relatedness In The Social Amoeba Dictyostelium Discoideum, Neil J. Buttery, Chandra N. Jack, Boahemaa Adu-Oppong, Kate T. Snyder, Christoper R L Thompson, David C. Queller, Joan E. Strassmann

Biology Faculty Publications & Presentations

One condition for the evolution of altruism is genetic relatedness between altruist and beneficiary, often achieved through active kin recognition. Here, we investigate the power of a passive process resulting from genetic drift during population growth in the social amoeba Dictyostelium discoideum. We put labelled and unlabelled cells of the same clone in the centre of a plate, and allowed them to proliferate outward. Zones formed by genetic drift owing to the small population of actively growing cells at the colony edge. We also found that single cells could form zones of high relatedness. Relatedness increased at a significantly …


Amino Acid Repeats Cause Extraordinary Coding Sequence Variation In The Social Amoeba Dictyostelium Discoideum, Clea Scala, Xiangjun Tian, Natasha J. Mehdiabadi, Margaret H. Smith, Gerda Saxer, Katie Stephens, Prince Buzombo, Joan E. Strassmann, David C. Queller Jan 2012

Amino Acid Repeats Cause Extraordinary Coding Sequence Variation In The Social Amoeba Dictyostelium Discoideum, Clea Scala, Xiangjun Tian, Natasha J. Mehdiabadi, Margaret H. Smith, Gerda Saxer, Katie Stephens, Prince Buzombo, Joan E. Strassmann, David C. Queller

Biology Faculty Publications & Presentations

Protein sequences are normally the most conserved elements of genomes owing to purifying selection to maintain their functions. We document an extraordinary amount of within-species protein sequence variation in the model eukaryote Dictyostelium discoideum stemming from triplet DNA repeats coding for long strings of single amino acids. D. discoideum has a very large number of such strings, many of which are polyglutamine repeats, the same sequence that causes various human neurological disorders in humans, like Huntington’s disease. We show here that D. discoideum coding repeat loci are highly variable among individuals, making D. discoideum a candidate for the most variable …


Why Wasp Foundresses Change Nests: Relatedness, Dominance, And Nest Quality, Perttu Seppä, David C. Queller, Joan E. Strassmann Jan 2012

Why Wasp Foundresses Change Nests: Relatedness, Dominance, And Nest Quality, Perttu Seppä, David C. Queller, Joan E. Strassmann

Biology Faculty Publications & Presentations

The costs and benefits of different social options are best understood when individuals can be followed as they make different choices, something that can be difficult in social insects. In this detailed study, we follow overwintered females of the social wasp Polistes carolina through different nesting strategies in a stratified habitat where nest site quality varies with proximity to a foraging area, and genetic relatedness among females is known. Females may initiate nests, join nests temporarily or permanently, or abandon nests. Females can become helpers or egglayers, effectively workers or queens. What they actually do can be predicted by a …


Whole Genome Sequencing Of Mutation Accumulation Lines Reveals A Low Mutation Rate In The Social Amoeba Dictyostelium Discoideum, Gerda Saxer, Paul Havlak, Sara A. Fox, Michael A. Quance, Sharu Gupta, Yuriy Fofanov, Joan E. Strassmann, David C. Queller Jan 2012

Whole Genome Sequencing Of Mutation Accumulation Lines Reveals A Low Mutation Rate In The Social Amoeba Dictyostelium Discoideum, Gerda Saxer, Paul Havlak, Sara A. Fox, Michael A. Quance, Sharu Gupta, Yuriy Fofanov, Joan E. Strassmann, David C. Queller

Biology Faculty Publications & Presentations

Spontaneous mutations play a central role in evolution. Despite their importance, mutation rates are some of the most elusive parameters to measure in evolutionary biology. The combination of mutation accumulation (MA) experiments and whole-genome sequencing now makes it possible to estimate mutation rates by directly observing new mutations at the molecular level across the whole genome. We performed an MA experiment with the social amoeba Dictyostelium discoideum and sequenced the genomes of three randomly chosen lines using high-throughput sequencing to estimate the spontaneous mutation rate in this model organism. The mitochondrial mutation rate of 6.76×10(-9), with a Poisson confidence interval …


Mscs-Like10 Is A Stretch-Activated Ion Channel From Arabidopsis Thaliana With A Preference For Anions, Grigory Maksaev, Elizabeth S. Haswell Jan 2012

Mscs-Like10 Is A Stretch-Activated Ion Channel From Arabidopsis Thaliana With A Preference For Anions, Grigory Maksaev, Elizabeth S. Haswell

Biology Faculty Publications & Presentations

Like many other organisms, plants are capable of sensing and responding to mechanical stimuli such as touch, osmotic pressure, and gravity. One mechanism for the perception of force is the activation of mechanosensitive (or stretch-activated) ion channels, and a number of mechanosensitive channel activities have been described in plant membranes. Based on their homology to the bacterial mechanosensitive channel MscS, the 10 MscS-Like (MSL) proteins of Arabidopsis thaliana have been hypothesized to form mechanosensitive channels in plant cell and organelle membranes. However, definitive proof that MSLs form mechanosensitive channels has been lacking. Here we used single-channel patch clamp electrophysiology to …


A Pre-Embedding Immunogold Approach Reveals Localization Of Myosin Vi At The Ultrastructural Level In The Actin Cones That Mediate Drosophila Spermatid Individualization, Marta Lenartowska, Mamiko Isaji, Kathryn G. Miller Jan 2012

A Pre-Embedding Immunogold Approach Reveals Localization Of Myosin Vi At The Ultrastructural Level In The Actin Cones That Mediate Drosophila Spermatid Individualization, Marta Lenartowska, Mamiko Isaji, Kathryn G. Miller

Biology Faculty Publications & Presentations

Stable actin structures play important roles in the development and specialization of differentiated cells. How these structures form, are organized, and are used to mediate physiological processes is not well understood in most cases. In Drosophila testis, stable actin structures, called actin cones, mediate spermatid individualization, a large-scale cellular remodeling process. These actin cones are composed of two structural domains, a front meshwork and a rear region of parallel bundles. Myosin VI is an important player in proper actin cone organization and function. Myosin VI localizes to the cones' fronts and its specific localization is required for proper actin cone …


A Role For Mechanosensitive Channels In Chloroplast And Bacterial Fission., Margaret E. Wilson, Elizabeth S. Haswell Jan 2012

A Role For Mechanosensitive Channels In Chloroplast And Bacterial Fission., Margaret E. Wilson, Elizabeth S. Haswell

Biology Faculty Publications & Presentations

The division site in both chloroplasts and bacteria is established by the medial placement of the FtsZ ring, a process that is in part regulated by the evolutionarily conserved components of the Min system. We recently showed that mechanosensitive ion channels influence FtsZ ring assembly in both Arabidopsis thaliana chloroplasts and in Escherichia coli; in chloroplasts they do so through the same genetic pathway as the Min system. Here we describe the effect of heterologous expression of the Arabidopsis MS channel homolog MSL2 on FtsZ ring placement in E. coli. We also discuss possible molecular mechanisms by which MS channels …


Plastids And Pathogens: Mechanosensitive Channels And Survival In A Hypoosmotic World, Kira M. Veley, Elizabeth S. Haswell Jan 2012

Plastids And Pathogens: Mechanosensitive Channels And Survival In A Hypoosmotic World, Kira M. Veley, Elizabeth S. Haswell

Biology Faculty Publications & Presentations

In bacteria, MscS-type mechanosensitive channels serve to protect cells from lysis as they swell during extreme osmotic stress. We recently showed that two MscS homologs from Arabidopsis thaliana serve a similar purpose in the epidermal plastids of the leaf, indicating that the plant cell cytoplasm can present a dynamic osmotic challenge to the plastid. MscS homologs are predicted to be targeted to both plastids and mitochondrial envelopes and have been found in the genomes of intracellular pathogens. Here we discuss the implications of these observations, and propose that MS channels provide an essential mechanism for osmotic adaptation to both intracellular …


Mechanosensitive Channels Protect Plastids From Hypoosmotic Stress During Normal Plant Growth, Kira M. Veley, Sarah Marshburn, Cara E. Clure, Elizabeth S. Haswell Jan 2012

Mechanosensitive Channels Protect Plastids From Hypoosmotic Stress During Normal Plant Growth, Kira M. Veley, Sarah Marshburn, Cara E. Clure, Elizabeth S. Haswell

Biology Faculty Publications & Presentations

Cellular response to osmotic stress is critical for survival and involves volume control through the regulated transport of osmolytes [1-3]. Organelles may respond similarly to abrupt changes in cytoplasmic osmolarity [4-6]. The plastids of the Arabidopsis thaliana leaf epidermis provide a model system for the study of organellar response to osmotic stress within the context of the cell. An Arabidopsis mutant lacking two plastid-localized homologs of the bacteria mechanosensitive channel MscS (MscS-like [MSL] 2 and 3) exhibits large round epidermal plastids that lack dynamic extensions known as stromules [7]. This phenotype is present under normal growth conditions and does not …


Functional Analysis Of Conserved Motifs In The Mechanosensitive Channel Homolog Mscs-Like2 From Arabidopsis Thaliana, Gregory S. Jensen, Elizabeth S. Haswell Jan 2012

Functional Analysis Of Conserved Motifs In The Mechanosensitive Channel Homolog Mscs-Like2 From Arabidopsis Thaliana, Gregory S. Jensen, Elizabeth S. Haswell

Biology Faculty Publications & Presentations

The Mechanosensitive channel of Small conductance (MscS) of Escherichia coli has become an excellent model system for the structural, biophysical, and functional study of mechanosensitive ion channels. MscS, a complex channel with multiple states, contributes to protection against lysis upon osmotic downshock. MscS homologs are widely and abundantly dispersed among the bacterial and plant lineages, but are not found in animals. Investigation into the eukaryotic branch of the MscS family is in the beginning stages, and it remains unclear how much MscS homologs from eukaryotes resemble E. coli MscS with respect to structure, function, and regulation. Here we test the …


Multi-Partner Interactions In Corals In The Face Of Climate Change, Koty H. Sharp, Kim B. Ritchie Jan 2012

Multi-Partner Interactions In Corals In The Face Of Climate Change, Koty H. Sharp, Kim B. Ritchie

Arts & Sciences Faculty Publications

Recent research has explored the possibility that increased sea-surface temperatures and decreasing pH (ocean acidification) contribute to the ongoing decline of coral reef ecosystems. Within corals, a diverse microbiome exerts significant influence on biogeochemical and ecological processes, including food webs, organismal life cycles, and chemical and nutrient cycling. Microbes on coral reefs play a critical role in regulating larval recruitment, bacterial colonization, and pathogen abundance under ambient conditions, ultimately governing the overall resilience of coral reef systems. As a result, microbial processes may be involved in reef ecosystem-level responses to climate change. Developments of new molecular technologies, in addition to …


Sharks Of The Devonian, Andrew Blitman Dec 2011

Sharks Of The Devonian, Andrew Blitman

Andrew Blitman

No abstract provided.