scholarly journals Novel Chlamydiae and Amoebophilus endosymbionts are prevalent in wild isolates of the model social amoebae Dictyostelium discoideum

2020 ◽  
Author(s):  
Tamara S. Haselkorn ◽  
Daniela Jimenez ◽  
Usman Bashir ◽  
Eleni Sallinger ◽  
David C. Queller ◽  
...  
Keyword(s):  
Dictyostelium Discoideum ◽  
Natural Populations ◽  
Model Organism ◽  
Future Research ◽  
Bacterial Strains ◽  
Symbiotic Relationships ◽  
Laboratory Conditions ◽  
Natural Isolates ◽  
History Of ◽  
Large Survey

SummaryAmoebae interact with bacteria in diverse and multifaceted ways. Amoeba predation can serve as a selective pressure for the development of bacterial virulence traits. Bacteria may also adapt to life inside amoebae, resulting in symbiotic relationships (pathogenic or mutualistic). Indeed, amoebae are often infected with bacterial endosymbionts. Acanthamoeba and Hartmannella harbor symbionts from five distinct lineages within the Proteobacteria, Bacteroidetes, and Chlamydiae. Here, we PCR-screened an extensive collection of Dictyostelium discoideum wild isolates for the presence of bacterial symbionts. For the first time we found that obligate symbionts are surprisingly common in this highly-studied amoeba species, identified in 42% of screened isolates (N=730). Members of the environmental Chlamydiae are particularly prevalent. These strains are novel and phylogenetically distinct. We also found Amoebophilus symbionts in 8% of screened isolates (N=730). Under laboratory conditions, antibiotic-cured amoebae behave similarly to their endosymbiont-infected counterparts, suggesting that endosymbionts do not significantly impact host fitness, at least in the laboratory. We found several natural isolates were co-infected with different endosymbionts. The high prevalence and novelty of amoeba endosymbiont clades in the model organism D. discoideum opens the door to future research on the significance and mechanisms of amoeba-symbiont interactions.Significance statementIn a large survey across the eastern US, we identify the presence and prevalence of novel strains of obligate intracellular symbionts from within the Chlamydiae, Amoebophilus, and Procabacter lineages in natural populations of the social amoeba Dictyostelium discoideum. We demonstrate that these symbionts do not affect amoeba fitness under standard laboratory conditions. High prevalences in natural populations and some non-random co-infection patterns suggest that these symbionts have environmental context-dependent effects. The presence of these novel bacterial strains that are highly diverged from known amoeba endosymbionts provides an opportunity to study host specificity and host-symbiont interactions in the well-studied D. discoideum model organism. It opens the door for exploring the evolutionary history of these widespread obligate symbionts that are associated with a large variety of hosts.

scholarly journals Does batrachotoxin autoresistance co-evolve with toxicity in Phyllobates poison-dart frogs?

2018 ◽  
Author(s):  
Roberto Márquez ◽  
Valeria Ramírez-Castañeda ◽  
Adolfo Amézquita
Keyword(s):  
Natural Populations ◽  
Future Research ◽  
Costs And Benefits ◽  
Evolutionary Mechanisms ◽  
Toxin Resistance ◽  
History Of ◽  
Fitness Tradeoffs ◽  
Living Organisms ◽  
The Relationship ◽  
Shed Light

AbstractToxicity is widespread among living organisms, and evolves as a multimodal phenotype. Part of this phenotype is the ability to avoid self-intoxication (autoresistance). Evolving toxin resistance can involve fitness tradeoffs, so autoresistance is often expected to evolve gradually and in tandem with toxicity, resulting in a correlation between the degrees of toxicity and autoresistance among toxic populations. We investigate this correlation in Phyllobates poison frogs, notorious for secreting batrachotoxin (BTX), a potent neurotoxin that targets sodium channels, using ancestral sequence reconstructions of BTX–sensing areas of the muscular voltage-gated sodium channel. Reconstructions suggest that BTX resistance arose at the root of Phyllobates, coinciding with the evolution of BTX secretion. After this event little or no further evolution of autoresistance seems to have occurred, despite large increases in toxicity throughout the history of these frogs. Our results therefore provide no evidence in favor of an evolutionary correlation between toxicity and autoresistance, which conflicts with previous work. Future research on the functional costs and benefits of mutations putatively involved in BTX resistance, as well as their prevalence in natural populations should shed light on the evolutionary mechanisms driving the relationship between toxicity and autoresistance in Phyllobates frogs.

scholarly journals The untapped potential of medaka and its wild relatives

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Leon Hilgers ◽  
Julia Schwarzer
Keyword(s):  
Current Knowledge ◽  
Model Organism ◽  
Single Species ◽  
Wild Relatives ◽  
Species Boundaries ◽  
Future Research ◽  
Important Goal ◽  
Evolutionary Context ◽  
In The Wild ◽  
History Of

The medaka is a fish that has served as a model organism for over a century, yet there is still much to learn about its life in the wild. Here we summarize the current knowledge, highlight recent progress and outline remaining gaps in our understanding of the natural history of medaka. It has also become clear over time that rather than being a single species, medaka comprises an entire species complex, so disentangling the species boundaries is an important goal for future research. Moreover, medaka and other ricefishes exhibit striking functional diversity, little of which has been investigated to date. As such, there are opportunities to use the resources developed for medaka to study other ricefishes, and to learn more about medaka itself in an evolutionary context.

scholarly journals Evolutionary history and classification of Micropia retroelements in Drosophilidae species

2019 ◽  
Author(s):  
Juliana Cordeiro ◽  
Tuane L. Carvalho ◽  
Vera L. da S. Valente ◽  
Lizandra J. Robe
Keyword(s):  
Regulatory Networks ◽  
Evolutionary History ◽  
Current Knowledge ◽  
Natural Populations ◽  
Model Organism ◽  
Genomic Databases ◽  
New Genes ◽  
Gypsy Group ◽  
History Of

AbstractCurrent knowledge indicates TEs have been shaping the evolution of genomes and host species, contributing to the creation of new genes and promoting rearrangements frequently associated with new regulatory networks. Support for these hypothesis frequently result from studies with model species, and Drosophila detaches as a great model organism to the study of TEs. Micropia belongs to the Ty3/Gypsy group of LTR retroelements, and comprises one of the least studied Drosophila transposable elements. In this study, we assessed the evolutionary history of Micropia within Drosophilidae, while trying to assist in the classification of this TE. At first, we analyzed its presence in the genome of several species from natural populations and then, based on searches within genomic databases, we retrieved Micropia-like sequences from distinct Drosophilidae species genomes. We expanded the knowledge of Micropia distribution within Drosophila, and detected an array of divergent sequences, which allowed subdividing this retroelement in 20 subfamilies. Even so, a patchy distribution of Micropia sequences within the Drosophilidae phylogeny could be identified combined with incongruences of the species and the Micropia phylogenies. Comparing dS values between Micropia and host nuclear sequences, we found several cases of unexpected high levels of similarity between Micropia sequences found in divergent species. All these findings propose a hypothesis to the evolution of Micropia within Drosophilidae, including several VTTs and HTTs events, associated to ancestral polymorphisms and recurrent Micropia sequences diversification.

scholarly journals The diversity of alleles at the hsd locus in natural populations of Escherichia coli.

Genetics ◽  
1995 ◽  
Vol 140 (4) ◽  
pp. 1187-1197
Author(s):  
V A Barcus ◽  
A J Titheradge ◽  
N E Murray
Keyword(s):  
Escherichia Coli ◽  
Natural Populations ◽  
Enteric Bacteria ◽  
Type I ◽  
Bacterial Strains ◽  
E Coli ◽  
Alternative Families ◽  
Type Ia ◽  
Natural Isolates ◽  
Id Genes

Abstract In enteric bacteria three discrete families of type I restriction and modification systems (IA, IB and ID) are encoded by alleles of the serB-linked hsd locus. Probes specific for each of the three families were used to monitor the distribution of related systems in 37 of the 72 wild-type Escherichia coli strains comprising the ECOR collection. All 25 members of group A in this collection were screened; 12 were probe-positive, nine have hsd genes in the IA family, two in the IB and one in the ID. Twelve strains, representing all groups other than A, were screened; five were probe-positive, one has hsd genes in the IA family, one in the IB and three in the ID. The type ID genes are the first representatives of this family in E. coli, the probe-negative strains could have alternative families of hsd genes. The type IA and IB systems added at least five new specificities to the five already identified in natural isolates of E. coli. The distribution of alleles is inconsistent with the dendrogram of the bacterial strains derived from other criteria. This discrepancy and the dissimilar coding sequences of allelic hsd genes both imply lateral transfer of hsd genes.

Bayesian Inference in Human Time Perception

2017 ◽  
Author(s):  
Darren Rhodes
Keyword(s):  
Time Perception ◽  
Likelihood Function ◽  
Human Perception ◽  
Future Research ◽  
Temporal Properties ◽  
History Of Research ◽  
Psychophysical Testing ◽  
History Of ◽  
Fundamental Dimension ◽  
Perception Of Time

Time is a fundamental dimension of human perception, cognition and action, as the perception and cognition of temporal information is essential for everyday activities and survival. Innumerable studies have investigated the perception of time over the last 100 years, but the neural and computational bases for the processing of time remains unknown. First, we present a brief history of research and the methods used in time perception and then discuss the psychophysical approach to time, extant models of time perception, and advancing inconsistencies between each account that this review aims to bridge the gap between. Recent work has advocated a Bayesian approach to time perception. This framework has been applied to both duration and perceived timing, where prior expectations about when a stimulus might occur in the future (prior distribution) are combined with current sensory evidence (likelihood function) in order to generate the perception of temporal properties (posterior distribution). In general, these models predict that the brain uses temporal expectations to bias perception in a way that stimuli are ‘regularized’ i.e. stimuli look more like what has been seen before. Evidence for this framework has been found using human psychophysical testing (experimental methods to quantify behaviour in the perceptual system). Finally, an outlook for how these models can advance future research in temporal perception is discussed.

Update on the Boundaries of the Curly Birch Range

2020 ◽  
pp. 9-21
Author(s):  
L.V. Vetchinnikova ◽  
◽  
A.F. Titov ◽  
◽  
Keyword(s):  
Population Size ◽  
Natural Populations ◽  
Forest Tree ◽  
Published Data ◽  
Population Approach ◽  
Key Factors ◽  
History Of ◽  
Individual Trees ◽  
Karelian Birch

The article reports on the application of the best known principles for mapping natural populations of curly (Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti – one of the most appealing representatives of the forest tree flora. Relying on the synthesis and analysis of the published data amassed over nearly 100 years and the data from own full-scale studies done in the past few decades almost throughout the area where curly birch has grown naturally, it is concluded that its range outlined in the middle of the 20th century and since then hardly revised is outdated. The key factors and reasons necessitating its revision are specified. Herewith it is suggested that the range is delineated using the population approach, and the key element will be the critical population size below which the population is no longer viable in the long term. This approach implies that the boundaries of the taxon range depend on the boundaries of local populations (rather than the locations of individual trees or small clumps of trees), the size of which should not be lower than the critical value, which is supposed to be around 100–500 trees for curly birch. A schematic map of the curly birch range delineated using this approach is provided. We specially address the problem of determining the minimum population size to secure genetic diversity maintenance. The advantages of the population approach to delineating the distribution range of curly birch with regard to its biological features are highlighted. The authors argue that it enables a more accurate delineation of the range; shows the natural evolutionary history of the taxon (although it is not yet officially recognized as a species) and its range; can be relatively easily updated (e.g. depending on the scope of reintroduction); should be taken into account when working on the strategy of conservation and other actions designed to maintain and regenerate this unique representative of the forest tree flora.

Fragments of the American Dream: Immigration, Race, and Medical Care in the Segregated South, 1929

Public Voices ◽  
2016 ◽  
Vol 13 (2) ◽  
pp. 1
Author(s):  
John R Phillips
Keyword(s):  
United States ◽  
American Dream ◽  
Black Population ◽  
The United States ◽  
Single Woman ◽  
Future Research ◽  
Legal Doctrine ◽  
Quarter Century ◽  
History Of ◽  
Sunflower County

The cover photograph for this issue of Public Voices was taken sometime in the summer of 1929 (probably June) somewhere in Sunflower County, Mississippi. Very probably the photo was taken in Indianola but, perhaps, it was Ruleville. It is one of three such photos, one of which does have the annotation on the reverse “Ruleville Midwives Club 1929.” The young woman wearing a tie in this and in one of the other photos was Ann Reid Brown, R.N., then a single woman having only arrived in the United States from Scotland a few years before, in 1923. Full disclosure: This commentary on the photo combines professional research interests in public administration and public policy with personal interests—family interests—for that young nurse later married and became the author’s mother. From the scholarly perspective, such photographs have been seen as “instrumental in establishing midwives’ credentials and cultural identity at a key transitional moment in the history of the midwife and of public health” (Keith, Brennan, & Reynolds 2012). There is also deep irony if we see these photographs as being a fragment of the American dream, of a recent immigrant’s hope for and success at achieving that dream; but that fragment of the vision is understood quite differently when we see that she began a hopeful career working with a Black population forcibly segregated by law under the incongruously named “separate but equal” legal doctrine. That doctrine, derived from the United States Supreme Court’s 1896 decision, Plessy v. Ferguson, would remain the foundation for legally enforced segregation throughout the South for another quarter century. The options open to the young, white, immigrant nurse were almost entirely closed off for the population with which she then worked. The remaining parts of this overview are meant to provide the following: (1) some biographical information on the nurse; (2) a description, in so far as we know it, of why she was in Mississippi; and (3) some indication of areas for future research on this and related topics.

Powerful Inscriptions: On the Semiotic Phenomenology of BDSM

2020 ◽  
Author(s):  
Richard Joseph Martin
Keyword(s):  
Future Research ◽  
Ethnographic Research ◽  
Linguistic Turn ◽  
Making Sense ◽  
Sociology Of Deviance ◽  
History Of ◽  
Semiotic Phenomenology ◽  
Sex Wars

BDSM encompasses a range of practices—bondage and discipline (BD), dominance and submission (DS), sadism and masochism (SM)—involving the consensual exchange of power in erotic contexts. This chapter provides an overview of scholarship on BDSM, drawing on the history of academic studies of the phenomenon, ranging from the psychology of perversion, the sociology of deviance, and the feminist “sex wars” to more recent ethnographic and phenomenological turns. The chapter focuses on the importance of discourse and affect for making sense of BDSM, both for those who seek to analyze the phenomenon and for practitioners themselves. Drawing on ethnographic research and other data, the chapter shows how language and discourse are key to answering interconnected questions about the semiotics and phenomenology of BDSM (what these practices mean and how practitioners experience these practices affectively). Thus, a potential “linguistic turn” in BDSM studies is essential for future research on this erotic minority.

Introduction

2017 ◽  
Author(s):  
Travis D. Stimeling
Keyword(s):  
United States ◽  
The United States ◽  
Country Music ◽  
Future Research ◽  
Music Culture ◽  
Rich Variety ◽  
Ethnographic Studies ◽  
Folklore Studies ◽  
History Of ◽  
The Rich

This chapter offers a historiographic survey of country music scholarship from the publication of Bill C. Malone’s “A History of Commercial Country Music in the United States, 1920–1964” (1965) to the leading publications of the today. Very little of substance has been written on country music recorded since the 1970s, especially when compared to the wealth of available literature on early country recording artists. Ethnographic studies of country music and country music culture are rare, and including ethnographic methods in country music studies offers new insights into the rich variety of ways in which people make, consume, and engage with country music as a genre. The chapter traces the influence of folklore studies, sociology, cultural studies, and musicology on the development of country music studies and proposes some directions for future research in the field.

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