scholarly journals Histoplasma variation and adaptive strategies for parasitism: new perspectives on histoplasmosis.

1991 ◽  
Vol 4 (4) ◽  
pp. 411-421 ◽  
Author(s):  
L G Eissenberg ◽  
W E Goldman
Keyword(s):  
Histoplasma Capsulatum ◽  
Immune Status ◽  
Phase Variation ◽  
Dynamic Environments ◽  
Phenotypic Switching ◽  
Adaptive Responses ◽  
Fungal Population ◽  
Persistent Infections ◽  
Wide Range ◽  
Natural Variations

This review summarizes the biology of Histoplasma capsulatum in relation to a wide variety of corresponding pathologies in histoplasmosis. Features of these disease syndromes can be explained in part by natural variations within the fungal population and adaptations made by individual organisms to specific environments. H. capsulatum grows as mycelia and conidia in the soil; once inhaled, the organism undergoes a dramatic morphological and physiological conversion to a yeast form. The yeasts proliferate within the phagolysosomes of macrophages, using a variety of specific strategies for intracellular survival. Even avirulent strains or variants are able to avoid being killed by macrophages and instead establish inapparent or persistent infections. The ingested avirulent organisms assume enlarged shapes similar in appearance to those seen in histological sections of tissues from patients with histoplasmosis. Respiratory tract epithelial cells also appear to play a role in persistence: within them yeasts undergo phenotypic switching akin to the phase variation observed in other pathogens. This particular change involves the loss or modification of cell wall alpha-(1,3)-glucan, which is also correlated with the spontaneous appearance of avirulent variants. The repertoire of adaptive responses and natural variations within this species probably evolved from the need to adjust to a wide range of dynamic environments. In combination with the immune status of the host, these characteristics of H. capsulatum appear to influence the epidemiology, extent, and persistence of histoplasmosis.

scholarly journals Adaptive responses in men fed low- and high-copper diets

2003 ◽  
Vol 90 (1) ◽  
pp. 161-168 ◽  
Author(s):  
Linda J. Harvey ◽  
Gosia Majsak-Newman ◽  
Jack R. Dainty ◽  
D. John Lewis ◽  
Nicola J. Langford ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Dietary Intervention ◽  
Limited Information ◽  
Adaptive Responses ◽  
Stable Isotope Label ◽  
Isotope Label ◽  
Adult Men ◽  
True Absorption ◽  
Wide Range ◽  
Cu Homeostasis

The study of Cu metabolism is hampered by a lack of sensitive and specific biomarkers of status and suitable isotopic labels, but limited information suggests that Cu homeostasis is maintained through changes in absorption and endogenous loss. The aim of the present study was to employ stable-isotope techniques to measure Cu absorption and endogenous losses in adult men adapted to low, moderate and high Cu-supplemented diets. Twelve healthy men, aged 20–59 years, were given diets containing 0·7, 1·6 and 6·0 mg Cu/d for 8 weeks, with at least 4 weeks intervening washout periods. After 6 weeks adaptation, apparent and true absorption of Cu were determined by measuring luminal loss and endogenous excretion of Cu following oral administration of 3 mg highly enriched65Cu stable-isotope label. Apparent and true absorption (41 and 48% respectively) on the low-Cu diet were not significantly different from the high-Cu diet (45 and 48% respectively). Endogenous losses were significantly reduced on the low- (0·45mg/d;P<0·001) and medium- (0·81 mg/d;P=0·001) compared with the high-Cu diet (2·46mg/d). No biochemical changes resulting from the dietary intervention were observed. Cu homeostasis was maintained over a wide range of intake and more rapidly at the lower intake, mainly through changes in endogenous excretion.

scholarly journals Immune Response of Galleria mellonella against Human Fungal Pathogens

2018 ◽  
Vol 5 (1) ◽  
pp. 3 ◽  
Author(s):  
Nuria Trevijano-Contador ◽  
Oscar Zaragoza
Keyword(s):  
Immune Response ◽  
Fungal Pathogens ◽  
Histoplasma Capsulatum ◽  
Galleria Mellonella ◽  
Low Cost ◽  
Innate Immune ◽  
Human Pathogens ◽  
Lytic Enzymes ◽  
Wide Range ◽  
Great Specificity

In many aspects, the immune response against pathogens in insects is similar to the innate immunity in mammals. This has caused a strong interest in the scientific community for the use of this model in research of host–pathogen interactions. In recent years, the use of Galleria mellonella larvae, an insect belonging to the Lepidoptera order, has emerged as an excellent model to study the virulence of human pathogens. It is a model that offers many advantages; for example, it is easy to handle and establish in every laboratory, the larvae have a low cost, and they tolerate a wide range of temperatures, including human temperature 37 °C. The immune response of G. mellonella is innate and is divided into a cellular component (hemocytes) and humoral component (antimicrobial peptides, lytic enzymes, and peptides and melanin) that work together against different intruders. It has been shown that the immune response of this insect has a great specificity and has the ability to distinguish between different classes of microorganisms. In this review, we delve into the different components of the innate immune response of Galleria mellonella, and how these components manifest in the infection of fungal pathogens including Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans, and Histoplasma capsulatum.

Development, learning and memory in large random networks of cortical neurons: lessons beyond anatomy

2002 ◽  
Vol 35 (1) ◽  
pp. 63-87 ◽  
Author(s):  
Shimon Marom ◽  
Goded Shahaf
Keyword(s):  
Functional Connectivity ◽  
Spontaneous Activity ◽  
Learning And Memory ◽  
Cortical Neurons ◽  
Ex Vivo ◽  
Adaptive Responses ◽  
Cortical Networks ◽  
Neural Learning ◽  
Wide Range ◽  
Activity Dependent

1. Introduction 631.1 Outline 631.2 Universals versus realizations in the study of learning and memory 642. Large random cortical networks developing ex vivo 652.1 Preparation 652.2 Measuring electrical activity 673. Spontaneous development 693.1 Activity 693.2 Connectivity 704. Consequences of spontaneous activity: pharmacological manipulations 724.1 Structural consequences 724.2 Functional consequences 735. Effects of stimulation 745.1 Response to focal stimulation 745.2 Stimulation-induced changes in connectivity 746. Embedding functionality in real neural networks 776.1 Facing the physiological definition of ‘reward’: two classes of theories 786.2 Closing the loop 797. Concluding remarks 848. Acknowledgments 859. References 85The phenomena of learning and memory are inherent to neural systems that differ from each other markedly. The differences, at the molecular, cellular and anatomical levels, reflect the wealth of possible instantiations of two neural learning and memory universals: (i) an extensive functional connectivity that enables a large repertoire of possible responses to stimuli; and (ii) sensitivity of the functional connectivity to activity, allowing for selection of adaptive responses. These universals can now be fully realized in ex-vivo developing neuronal networks due to advances in multi-electrode recording techniques and desktop computing. Applied to the study of ex-vivo networks of neurons, these approaches provide a unique view into learning and memory in networks, over a wide range of spatio-temporal scales. In this review, we summarize experimental data obtained from large random developing ex-vivo cortical networks. We describe how these networks are prepared, their structure, stages of functional development, and the forms of spontaneous activity they exhibit (Sections 2–4). In Section 5 we describe studies that seek to characterize the rules of activity-dependent changes in neural ensembles and their relation to monosynaptic rules. In Section 6, we demonstrate that it is possible to embed functionality into ex-vivo networks, that is, to teach them to perform desired firing patterns in both time and space. This requires ‘closing a loop’ between the network and the environment. Section 7 emphasizes the potential of ex-vivo developing cortical networks in the study of neural learning and memory universals. This may be achieved by combining closed loop experiments and ensemble-defined rules of activity-dependent change.

Nanostructured Selenium for Preventing Biofilm Formation on Medical Devices

2012 ◽  
Vol 1415 ◽  
Author(s):  
Qi Wang ◽  
Thomas J. Webster
Keyword(s):  
Staphylococcus Aureus ◽  
Medical Device ◽  
Medical Devices ◽  
Biofilm Formation ◽  
In Vitro Study ◽  
Common Cause ◽  
Persistent Infections ◽  
Wide Range ◽  
Novel Material

ABSTRACTBiofilms are a common cause of persistent infections on medical devices as they are easy to form and hard to treat. Selenium and its compounds are considered to be a novel material for a wide range of applications including anticancer applications and antibacterial applications. The objective of this study was to coat selenium nanoparticles on the surface of polycarbonate medical devices and examine their effectiveness at preventing biofilm formation. The results of this in vitro study showed that the selenium coating significantly inhibited Staphylococcus aureus growth on the surface of polycarbonate after 24 hours. Thus, this study suggests that coating polymers with nanostructured selenium is a fast and effective way to reduce bacteria functions leading to medical device infections.

Climate, Oceans, and the Law of Special and General Adaptation

2016 ◽  
Author(s):  
U. Rashid Sumaila
Keyword(s):  
Climate Change ◽  
Climate Change Impacts ◽  
Climate Impacts ◽  
Adaptive Responses ◽  
Wide Range ◽  
General Adaptation ◽  
The Law ◽  
Adaptation Law ◽  
Private Actors ◽  
International Fisheries

This chapter describes the literature of adaptation law in the context of international ocean governance. Adaptation law consists of rules aimed at minimizing the social costs associated with human response to climate impacts. These can be used to shape the behaviour of private actors or public institutions. The law sometimes might provide incentives to make enterprises more resilient as it makes capital unnecessarily stranded during climate change. In order to illustrate the challenges of implementation in the ocean context, the chapter focuses on two examples: international fisheries and ‘mari-engineering’. International fisheries represent ongoing ocean use and regulated by a well-developed body of international law. Due to the wide range of possible climate impacts and adaptive responses, proactive changes to existing fisheries rules in anticipation of climate change fit into the category of general adaptation law, while mari-engineering is engineering the seas to slow or halt climate change impacts.

Role of nuclear factor κB and mitogen-activated protein kinase signaling in exercise-induced antioxidant enzyme adaptation

2007 ◽  
Vol 32 (5) ◽  
pp. 930-935 ◽  
Author(s):  
Li Li Ji ◽  
Maria-Carmen Gomez-Cabrera ◽  
Jose Vina
Keyword(s):  
Protein Kinase ◽  
Nuclear Factor Κb ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Ros Generation ◽  
Nuclear Factor ◽  
Adaptive Responses ◽  
Wide Range ◽  
Mitogen Activated Protein ◽  
Exercise Induced

Activation of nuclear factor (NF) κB and mitogen-activated protein kinase (MAPK) pathways in skeletal muscle has been shown to enhance the gene expression of several enzymes that play an important role in maintaining oxidant–antioxidant homeostasis, such as mitochondrial superoxide dismutase (MnSOD) and inducible nitric oxide synthase (iNOS). While an acute bout of exercise activates NFκB and MAPK signaling and upregulates MnSOD and iNOS, administration of chemical agents that suppress reactive oxygen species (ROS) production can cause attenuation of exercise-induced MnSOD and iNOS expression. Thus, ROS generation during exercise may have duel effects: the infliction of oxidative stress and damage, and the stimulation of adaptive responses favoring long-term protection. This scenario explains why animals and humans involved in exercise training have demonstrated increased resistance to oxidative damage under a wide range of physiological and pathological stresses.

Genetic and phenotypic component in head shape of common wall lizard Podarcis muralis

2016 ◽  
Vol 37 (3) ◽  
pp. 301-310 ◽  
Author(s):  
Roberto Sacchi ◽  
Marco Mangiacotti ◽  
Stefano Scali ◽  
Michele Ghitti ◽  
Beatrice Bindolini ◽  
...  
Keyword(s):  
Natural Selection ◽  
Morphological Differentiation ◽  
Phenotypic Change ◽  
Adaptive Responses ◽  
Head Shape ◽  
Heritable Variation ◽  
Podarcis Muralis ◽  
Environmental Pressures ◽  
Common Wall ◽  
Wide Range

Head shape in lizards correlates with a wide range of environmental pressures, supporting the hypothesis that patterns of phenotypic change represent adaptive responses to selective processes. However, natural selection promotes evolutionary adaptation only if the trait under selection has enough heritable variation. In this study we used geometric morphometrics and quantitative genetics to assess the heritability patterns of the head shape and size of common wall lizards (Podarcis muralis). Genetic and phenotypic components were estimated using animal models, which showed that more than half of the variation in head morphology is inheritable. Furthermore, at least five independent patterns of genetically determined phenotypic change were detected. These outcomes confirm that morphological differentiation in common wall lizards may reliably be regarded as the result of adaptive processes driven by natural selection.

Variation in the Vigna lanceolata complex for traits of taxonomic, adaptive or agronomic interest

2003 ◽  
Vol 51 (3) ◽  
pp. 295 ◽  
Author(s):  
R. J. Lawn ◽  
A. E. Holland
Keyword(s):  
Taxonomic Revision ◽  
Visual Assessment ◽  
Stress Reactions ◽  
Adaptive Responses ◽  
Qualitative And Quantitative ◽  
Geographically Dispersed ◽  
Wide Range ◽  
Chance Occurrence ◽  
Plant Habit ◽  
Extensive Collection

Variation was assessed in the endemic Australian herbaceous legume, V. lanceolata Benth., by using an extensive collection of accessions that sampled a wide range of geographically dispersed collection sites. Attributes were evaluated under natural conditions at the time of collection and in field-grown plants in coastal south-eastern Queensland. Qualitative and quantitative measures were taken of traits reflecting plant habit, floral, vegetative and reproductive morphology, phenology and stress reactions. On the basis of visual assessment, accessions were subjectively allocated into seven previously reported morphotypes. Analysis of the variation confirmed that there were large differences among the putative morphotypes relative to that among the accessions within morphotypes. Significant correlations between accession means for some traits provided further evidence that V. lanceolata is not a homogeneous species and has differentiated into forms with sharply defined aggregations of distinctive traits. In addition, correlations between some traits and the latitude or longitude of collection implied a geographic component to the differentiation among accessions and morphotypes. In some instances, these changes were associated with adaptive responses, but in others may reflect chance occurrence. Cluster analysis confirmed the authenticity of the morphotype groups and provided information on the levels of affinity between them. It is concluded that V. lanceolata is a 'complex' of related taxa and that taxonomic revision is warranted. The information documented through the study provides the basis for that revision and also identifies several attributes of adaptive and/or agronomic significance.

scholarly journals Origins of Transcriptional Transition: Balance between Upstream and Downstream Regulatory Gene Sequences

mBio ◽  
2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Adrien Sala ◽  
Muhammad Shoaib ◽  
Olga Anufrieva ◽  
Gnanavel Mutharasu ◽  
Olli Yli-Harja ◽  
...  
Keyword(s):  
Transition Rate ◽  
Regulatory Gene ◽  
Mrna Level ◽  
Phase Variation ◽  
Time Lapse ◽  
Population Diversity ◽  
Phenotypic Switching ◽  
Growth Phases ◽  
Cell Level ◽  
Burst Frequency

ABSTRACT By measuring individual mRNA production at the single-cell level, we investigated the lac promoter’s transcriptional transition during cell growth phases. In exponential phase, variation in transition rates generates two mixed phenotypes, low and high numbers of mRNAs, by modulating their burst frequency and sizes. Independent activation of the regulatory-gene sequence does not produce bimodal populations at the mRNA level, but bimodal populations are produced when the regulatory gene is activated coordinately with the upstream and downstream region promoter sequence (URS and DRS, respectively). Time-lapse microscopy of mRNAs for lac and a variant lac promoter confirm this observation. Activation of the URS/DRS elements of the promoter reveals a counterplay behavior during cell phases. The promoter transition rate coupled with cell phases determines the mRNA and transcriptional noise. We further show that bias in partitioning of RNA does not lead to phenotypic switching. Our results demonstrate that the balance between the URS and the DRS in transcriptional regulation determines population diversity. IMPORTANCE By measuring individual mRNA production at the single-cell level, we investigated the lac promoter transcriptional transition during cell growth phases. In exponential phase, variation in transition rate generates two mixed phenotypes producing low and high numbers of mRNAs by modulating the burst frequency and size. Independent activation of the regulatory gene sequence does not produce bimodal populations at the mRNA level, while it does when activated together through the coordination of upstream/downstream promoter sequences (URS/DRS). Time-lapse microscopy of mRNAs for lac and a lac variant promoter confirm this observation. Activation of the URS/DRS elements of the promoter reveals a counterplay behavior during cell phases. The promoter transition rate coupled with cell phases determines the mRNA and transcriptional noise. We further show that bias in partitioning of RNA does not lead to phenotypic switching. Our results demonstrate that the balance between URS and DRS in transcription regulation is determining the population diversity.

scholarly journals Phenotypic Switching in Mycoplasma gallisepticum Hemadsorption Is Governed by a High-Frequency, Reversible Point Mutation

2003 ◽  
Vol 71 (3) ◽  
pp. 1265-1273 ◽  
Author(s):  
Florian Winner ◽  
Ivana Markovà ◽  
Peter Much ◽  
Albin Lugmair ◽  
Karin Siebert-Gulle ◽  
...  
Keyword(s):  
High Frequency ◽  
Stop Codon ◽  
Phase Variation ◽  
Mycoplasma Gallisepticum ◽  
Chronic Respiratory Disease ◽  
Transcription Unit ◽  
Phenotypic Switching ◽  
Base Substitution ◽  
Mutational Event ◽  
Repeated Motifs

ABSTRACT Mycoplasma gallisepticum is a flask-shaped organism that commonly induces chronic respiratory disease in chickens and infectious sinusitis in turkeys. Phenotypic switching in M. gallisepticum hemadsorption (HA) was found to correlate with phase variation of the GapA cytadhesin concurrently with that of the CrmA protein, which exhibits cytadhesin-related features and is encoded by a gene located downstream of the gapA gene as part of the same transcription unit. In clones derived from strain Rlow, detailed genetic analyses further revealed that on-off switching in GapA expression is governed by a reversible base substitution occurring at the beginning of the gapA structural gene. In HA− variants, this event generates a stop codon that results in the premature termination of GapA translation and consequently affects the expression of CrmA. Sequences flanking the mutation spot do not feature any repeated motifs that could account for error-prone mutation via DNA slippage and the exact mechanism underlying this high-frequency mutational event remains to be elucidated. An HA− mutant deficient in producing CrmA, mHAD3, was obtained by disrupting the crmA gene by using transposition mutagenesis. Despite a fully functional gapA gene, the amount of GapA detected in this mutant was considerably lower than in HA+ clonal variants, suggesting that, in absence of CrmA, GapA might be subjected to a higher turnover.

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