scholarly journals Transgenerational plasticity in the eye size of Daphnia

2021 ◽  
Vol 17 (6) ◽  
pp. 20210143
Author(s):  
Matthew R. Walsh ◽  
Michael K. Gillis
Keyword(s):  
Adaptive Response ◽  
Sensory System ◽  
Environmental Stressor ◽  
Daphnia Pulicaria ◽  
High Quality ◽  
Environmental Signals ◽  
Transgenerational Plasticity ◽  
Eye Size ◽  
Offspring Generation ◽  
Phenotypic Responses

It is well established that environmental signals can induce phenotypic responses that persist for multiple generations. The induction of such ‘transgenerational plasticity’ (TGP) depends upon the ability of organisms to accurately receive and process information from environmental signals. Thus, sensory systems are likely intertwined with TGP. Here we tested the link between an environmental stressor and transgenerational responses in a component of the sensory system (eye size) that is linked to enhanced vision and ecologically relevant behaviours. We reared 45 clones of Daphnia pulicaria in the presence and absence of a low-quality resource (cyanobacteria) and evaluated shifts in relative eye size in offspring. Our results revealed divergent shifts in relative eye size within- and across-generations. Parental Daphnia that were fed cyanobacteria produced a smaller eye than Daphnia fed high-quality algae. Such differences were then reversed in the offspring generation; Daphnia whose mothers were fed cyanobacteria produced larger eyes than Daphnia that were continually fed green algae. We discuss the extent to which this maternal effect on eye size is an adaptive response linked to improved foraging.

scholarly journals Local adaptation in transgenerational responses to predators

2016 ◽  
Vol 283 (1823) ◽  
pp. 20152271 ◽  
Author(s):  
Matthew R. Walsh ◽  
Todd Castoe ◽  
Julian Holmes ◽  
Michelle Packer ◽  
Kelsey Biles ◽  
...  
Keyword(s):  
Local Adaptation ◽  
Temporal Dynamics ◽  
Temporal Stability ◽  
Natural Populations ◽  
Environmental Signals ◽  
Transgenerational Plasticity ◽  
Multiple Generations ◽  
Environmental Perturbations ◽  
Large Gradient ◽  
Phenotypic Responses

Environmental signals can induce phenotypic changes that span multiple generations. Along with phenotypic responses that occur during development (i.e. ‘within-generation’ plasticity), such ‘transgenerational plasticity’ (TGP) has been documented in a diverse array of taxa spanning many environmental perturbations. New theory predicts that temporal stability is a key driver of the evolution of TGP. We tested this prediction using natural populations of zooplankton from lakes in Connecticut that span a large gradient in the temporal dynamics of predator-induced mortality. We reared more than 120 clones of Daphnia ambigua from nine lakes for multiple generations in the presence/absence of predator cues. We found that temporal variation in mortality selects for within-generation plasticity while consistently strong (or weak) mortality selects for increased TGP. Such results provide us the first evidence for local adaptation in TGP and argue that divergent ecological conditions select for phenotypic responses within and across generations.

scholarly journals Development of a Dynamic Virtual Reality Model of the Inner Ear Sensory System as a Learning and Demonstrating Tool

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
P. Selva ◽  
J. Morlier ◽  
Y. Gourinat
Keyword(s):  
Virtual Reality ◽  
Inner Ear ◽  
Sensory System ◽  
The Body ◽  
Modeling Language ◽  
High Quality ◽  
Simulink Model ◽  
Virtual Reality Modeling Language ◽  
Cad Models ◽  
Virtual Reality Model

In order to keep track of the position and motion of our body in space, nature has given us a fascinating and very ingenious organ, the inner ear. Each inner ear includes five biological sensors—three angular and two linear accelerometers—which provide the body with the ability to sense angular and linear motion of the head with respect to inertial space. The aim of this paper is to present a dynamic virtual reality model of these sensors. This model, implemented in MATLAB/Simulink, simulates the rotary chair testing which is one of the tests carried out during a diagnosis of the vestibular system. High-quality 3D animations linked to the Simulink model are created using the export of CAD models into Virtual Reality Modeling Language (VRML) files. This virtual environment shows not only the test but also the state of each sensor (excited or inhibited) in real time. Virtual reality is used as a tool of integrated learning of the dynamic behavior of the inner ear using ergonomic paradigm of user interactivity (zoom, rotation, mouse interaction, etc.). It can be used as a learning and demonstrating tool either in the medicine field—to understand the behavior of the sensors during any kind of motion—or in the aeronautical field to relate the inner ear functioning to some sensory illusions.

scholarly journals Ordered patterning of the sensory system is susceptible to stochastic features of gene expression

2019 ◽  
Author(s):  
Ritika Giri ◽  
Dimitrios K. Papadopoulos ◽  
Diana M. Posadas ◽  
Hemanth K. Potluri ◽  
Pavel Tomancak ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Sensory System ◽  
Intrinsic Noise ◽  
Protein Abundance ◽  
Dependent Manner ◽  
Genomic Locus ◽  
Critical Feature ◽  
Environmental Signals ◽  
Microrna Regulation

AbstractSensory neuron numbers and positions are precisely organized to accurately map environmental signals in the brain. However, this precision must emerge from biochemical processes within and between cells that are stochastic. We measured intrinsic noise in senseless protein output, a key determinant of sensory fate, during Drosophila development. Perturbing microRNA regulation or genomic locus of senseless transcription produced distinct noise signatures. Genomic location altered protein stochasticity in an allelic-pairing dependent manner (transvection). This generated sensory pattern disorder without perturbing protein abundance. In contrast, loss of microRNA repression of senseless increased protein abundance but not sensory pattern disorder. This suggests that gene expression stochasticity is a critical feature that must be constrained during development to allow rapid yet accurate cell fate resolution.One Sentence SummaryLife on the Margin: balancing speed and accuracy during animal development.

scholarly journals Ordered patterning of the sensory system is susceptible to stochastic features of gene expression

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Ritika Giri ◽  
Dimitrios K Papadopoulos ◽  
Diana M Posadas ◽  
Hemanth K Potluri ◽  
Pavel Tomancak ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Sensory System ◽  
Critical Feature ◽  
Environmental Signals ◽  
Microrna Regulation ◽  
Biochemical Processes ◽  
Genomic Location ◽  
In Trans ◽  
The Brain

Sensory neuron numbers and positions are precisely organized to accurately map environmental signals in the brain. This precision emerges from biochemical processes within and between cells that are inherently stochastic. We investigated impact of stochastic gene expression on pattern formation, focusing on senseless (sens), a key determinant of sensory fate in Drosophila. Perturbing microRNA regulation or genomic location of sens produced distinct noise signatures. Noise was greatly enhanced when both sens alleles were present in homologous loci such that each allele was regulated in trans by the other allele. This led to disordered patterning. In contrast, loss of microRNA repression of sens increased protein abundance but not sensory pattern disorder. This suggests that gene expression stochasticity is a critical feature that must be constrained during development to allow rapid yet accurate cell fate resolution.

Red shiners (Cyprinella lutrensis) have larger eyes in turbid habitats

2012 ◽  
Vol 90 (12) ◽  
pp. 1431-1436 ◽  
Author(s):  
M.B. Dugas ◽  
N.R. Franssen
Keyword(s):  
Great Plains ◽  
Sensory System ◽  
Sensory Information ◽  
The United States ◽  
Population Variation ◽  
Ambient Light ◽  
Costs And Benefits ◽  
Eye Size ◽  
Cyprinella Lutrensis ◽  
Sensory Evolution

The costs and benefits of investing in expensive sensory systems are shaped by environments that vary in the ease with which sensory information can be accessed. Fish provide an excellent model system in which to address questions of sensory evolution; while fishes rely heavily on vision, their visual environment is far more diverse and challenging than that of terrestrial animals. Turbidity, for example, alters the quantity of ambient light, its color, and the ability of animals to resolve borders of objects. Several comparative studies suggest that turbidity is associated with a reduction in the resources devoted to vision. Using these as a guide, we tested the prediction that turbidity and eye size would be negatively associated in populations of red shiners ( Cyprinella lutrensis (Baird and Girard, 1853)), a small-bodied cyprinid that is common and abundant in habitats spanning nearly the entire range of turbidity found in the Great Plains of the United States. We found that eye size was positively associated with turbidity, perhaps surprising given previous comparative work, but consistent with the finding that red shiners from turbid habitats display more intense nuptial coloration. This result highlights the need for further investigations of among-population variation to fully understand the mechanisms underlying sensory system diversity in animals.

scholarly journals Epigenetic, transcriptional and phenotypic responses in two generations of Daphnia magna exposed to the DNA methylation inhibitor 5-azacytidine

2019 ◽  
Vol 5 (3) ◽  
Author(s):  
Leif Christopher Lindeman ◽  
Jens Thaulow ◽  
You Song ◽  
Jorke H Kamstra ◽  
Li Xie ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Histone Modifications ◽  
Environmental Stressors ◽  
Global Dna Methylation ◽  
Two Generations ◽  
Methylation Inhibitor ◽  
Dna Methylation Inhibitor ◽  
Offspring Generation ◽  
Phenotypic Responses

Abstract The water flea Daphnia magna is a keystone species in freshwater ecosystems and has been widely used as a model organism in environmental ecotoxicology. This aquatic crustacean is sensitive to environmental stressors and displays considerable plasticity in adapting to changing environmental conditions. Part of this plasticity may be due to epigenetic regulation of gene expression, including changes to DNA methylation and histone modifications. Because of the generally hypomethylated genome of this species, we hypothesized that the histone code may have an essential role in the epigenetic control and that histone modifications might be an early marker for stress. This study aims to characterize the epigenetic, transcriptional and phenotypic responses and their causal linkages in directly exposed adult (F0) Daphnia and peritoneal exposed neonates (F1) after a chronic (7-day) exposure to a sublethal concentration (10 mg/l) of 5-azacytidine, a well-studied vertebrate DNA methylation inhibitor. Exposure of the F0 generation significantly reduced the cumulative fecundity, accompanied with differential expression of genes in the one-carbon-cycle metabolic pathway. In the epigenome of the F0 generation, a decrease in global DNA methylation, but no significant changes on H3K4me3 or H3K27me3, were observed. In the F1 offspring generation, changes in gene expression, a significant reduction in global DNA methylation and changes in histone modifications were identified. The results indicate that exposure during adulthood may result in more pronounced effects on early development in the offspring generation, though interpretation of the data should be carefully done since both the exposure regime and developmental period is different in the two generations examined. The obtained results improve our understanding of crustacean epigenetics and the tools developed may promote use of epigenetic markers in hazard assessment of environmental stressors.

Some problems of objective-prism spectra classification

1966 ◽  
Vol 24 ◽  
pp. 51-52
Author(s):  
E. K. Kharadze ◽  
R. A. Bartaya
Keyword(s):  
Short Wave ◽  
High Quality ◽  
Stellar Spectra ◽  
Objective Prism

The unique 70-cm meniscus-type telescope of the Abastumani Astrophysical Observatory supplied with two objective prisms and the seeing conditions characteristic at Mount Kanobili (Abastumani) permit us to obtain stellar spectra of a high quality. No additional design to improve the “climate” immediately around the telescope itself is being applied. The dispersions and photographic magnitude limits are 160 and 660Å/mm, and 12–13, respectively. The short-wave end of spectra reaches 3500–3400Å.

A non-cyanide method of electropolishing silver

1978 ◽  
Vol 36 (1) ◽  
pp. 146-147
Author(s):  
R. L. Lyles ◽  
S. J. Rothman ◽  
W. Jäger
Keyword(s):  
Electron Microscopy ◽  
Sulphuric Acid ◽  
Methyl Alcohol ◽  
Health Hazards ◽  
Silver Alloy ◽  
High Quality ◽  
Silver Alloys ◽  
Free Sample ◽  
Specimen Quality ◽  
Standard Techniques

Standard techniques of electropolishing silver and silver alloys for electron microscopy in most instances have relied on various CN recipes. These methods have been characteristically unsatisfactory due to difficulties in obtaining large electron transparent areas, reproducible results, adequate solution lifetimes, and contamination free sample surfaces. In addition, there are the inherent health hazards associated with the use of CN solutions. Various attempts to develop noncyanic methods of electropolishing specimens for electron microscopy have not been successful in that the specimen quality problems encountered with the CN solutions have also existed in the previously proposed non-cyanic methods.The technique we describe allows us to jet polish high quality silver and silver alloy microscope specimens with consistant reproducibility and without the use of CN salts.The solution is similar to that suggested by Myschoyaev et al. It consists, in order of mixing, 115ml glacial actic acid (CH3CO2H, specific wt 1.04 g/ml), 43ml sulphuric acid (H2SO4, specific wt. g/ml), 350 ml anhydrous methyl alcohol, and 77 g thiourea (NH2CSNH2).

A High Resolution Scanning Microscope

1968 ◽  
Vol 26 ◽  
pp. 356-357
Author(s):  
A. V. Crewe ◽  
J. Wall ◽  
L. M. Welter
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Spherical Aberration ◽  
Focal Length ◽  
Spot Size ◽  
Emission Source ◽  
Field Of View ◽  
Scanning Microscope ◽  
Magnetic Lens ◽  
High Quality

A scanning microscope using a field emission source has been described elsewhere. This microscope has now been improved by replacing the single magnetic lens with a high quality lens of the type described by Ruska. This lens has a focal length of 1 mm and a spherical aberration coefficient of 0.5 mm. The final spot size, and therefore the microscope resolution, is limited by the aberration of this lens to about 6 Å.The lens has been constructed very carefully, maintaining a tolerance of + 1 μ on all critical surfaces. The gun is prealigned on the lens to form a compact unit. The only mechanical adjustments are those which control the specimen and the tip positions. The microscope can be used in two modes. With the lens off and the gun focused on the specimen, the resolution is 250 Å over an undistorted field of view of 2 mm. With the lens on,the resolution is 20 Å or better over a field of view of 40 microns. The magnification can be accurately varied by attenuating the raster current.

Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling

1995 ◽  
Vol 53 ◽  
pp. 512-513
Author(s):  
L. Mulestagno ◽  
J.C. Holzer ◽  
P. Fraundorf
Keyword(s):  
Sample Preparation ◽  
Milling Time ◽  
High Density ◽  
Low Density ◽  
Ion Milling ◽  
High Quality ◽  
Variable Angle ◽  
Major Disadvantage ◽  
Induced Defects

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).

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