scholarly journals Viruses infecting a warm water picoeukaryote shed light on spatial co-occurrence dynamics of marine viruses and their hosts

2021 ◽  
Author(s):  
Charles Bachy ◽  
Charmaine C. M. Yung ◽  
David M. Needham ◽  
Maria Consuelo Gazitúa ◽  
Simon Roux ◽  
...  
Keyword(s):  
Time Course ◽  
Productive Infection ◽  
Molecular Diagnostic ◽  
Sargasso Sea ◽  
Marine Viruses ◽  
Infection Parameters ◽  
Lower Temperature ◽  
Close Relatedness ◽  
Shed Light ◽  
Diagnostic Support

AbstractThe marine picoeukaryote Bathycoccus prasinos has been considered a cosmopolitan alga, although recent studies indicate two ecotypes exist, Clade BI (B. prasinos) and Clade BII. Viruses that infect Bathycoccus Clade BI are known (BpVs), but not that infect BII. We isolated three dsDNA prasinoviruses from the Sargasso Sea against Clade BII isolate RCC716. The BII-Vs do not infect BI, and two (BII-V2 and BII-V3) have larger genomes (~210 kb) than BI-Viruses and BII-V1. BII-Vs share ~90% of their proteins, and between 65% to 83% of their proteins with sequenced BpVs. Phylogenomic reconstructions and PolB analyses establish close-relatedness of BII-V2 and BII-V3, yet BII-V2 has 10-fold higher infectivity and induces greater mortality on host isolate RCC716. BII-V1 is more distant, has a shorter latent period, and infects both available BII isolates, RCC716 and RCC715, while BII-V2 and BII-V3 do not exhibit productive infection of the latter in our experiments. Global metagenome analyses show Clade BI and BII algal relative abundances correlate positively with their respective viruses. The distributions delineate BI/BpVs as occupying lower temperature mesotrophic and coastal systems, whereas BII/BII-Vs occupy warmer temperature, higher salinity ecosystems. Accordingly, with molecular diagnostic support, we name Clade BII Bathycoccus calidus sp. nov. and propose that molecular diversity within this new species likely connects to the differentiated host-virus dynamics observed in our time course experiments. Overall, the tightly linked biogeography of Bathycoccus host and virus clades observed herein supports species-level host specificity, with strain-level variations in infection parameters.

scholarly journals Characterization of a Potent Refractory State and Persistence of Herpes Simplex Virus 1 in Cell Culture

2006 ◽  
Vol 80 (18) ◽  
pp. 9171-9180 ◽  
Author(s):  
Cristina Barreca ◽  
Peter O'Hare
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Time Course ◽  
Fluorescent Protein ◽  
Productive Infection ◽  
Transcriptional Level ◽  
Cell Recovery ◽  
Extracellular Virus ◽  
Refractory State ◽  
Simplex Virus

ABSTRACT Herpes simplex virus (HSV) normally undergoes productive cytocidal infection in culture and is thought of as relatively resistant to innate immune responses such as interferon. We previously described an unusual pattern of infection in culture in MDBK cells, which after initial productive infection, surprisingly resulted in progressive suppression of replication and cell recovery. The dominance of the refractory state was due to the inability to suppress interferon production and subsequent paracrine signaling. Here, using a wild-type HSV-1 strain expressing green fluorescent protein (GFP)-VP16, we analyze aspects of long-term HSV persistence resulting from this oscillating refractory state. We show that the gradual suppression of GFP-VP16 expression correlated with a biphasic pattern of accumulation of viral DNA and extracellular virus titers. We quantify virus maintenance in a minor subpopulation of cells during subculture, show the reemergence of virus by infectious center assay, and demonstrate that this required intracellular events over a 24- to 48-h time course. We also demonstrate that conditioned medium (cMed) from infected cells induced a profound shutoff of HSV gene expression at the transcriptional level. Finally, we demonstrate that this suppression was extremely rapid, requiring only 1 h of treatment to essentially abolish HSV immediate-early expression, and surprisingly persisted for almost 2 days after removal of the cMed. These combined effects underpin the oscillating effect both in plaque progression, where infection spreads but is overwhelmed by the accumulation of inhibitory components, enabling cell recovery, and virus maintenance in a subpopulation of cells. These results may be relevant to consider in studies of HSV latency in different animal models.

scholarly journals Marine viruses discovered via metagenomics shed light on viral strategies throughout the oceans

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Felipe H. Coutinho ◽  
Cynthia B. Silveira ◽  
Gustavo B. Gregoracci ◽  
Cristiane C. Thompson ◽  
Robert A. Edwards ◽  
...  
Keyword(s):  
Marine Viruses ◽  
Shed Light

Larval fishes of a Middle Atlantic Bight estuary: assemblage structure and temporal stability

1999 ◽  
Vol 56 (2) ◽  
pp. 222-230 ◽  
Author(s):  
David A Witting ◽  
Kenneth W Able ◽  
Michael P Fahay
Keyword(s):  
Continental Shelf ◽  
Dominant Species ◽  
Fish Assemblages ◽  
Larval Fish ◽  
Temporal Stability ◽  
Temperature Cycle ◽  
Sargasso Sea ◽  
Larval Fishes ◽  
Middle Atlantic ◽  
Lower Temperature

We collected weekly, quantitative ichthyoplankton samples over 6 years (1989-1994, 1309 samples) to identify temporal scales of variability in the abundance and occurrence of larval fish assemblages near Little Egg Inlet in southern New Jersey, U.S.A. We collected species that spawn in the estuary (30%), both the estuary and continental shelf (35%), continental shelf (25%), and the Sargasso Sea (10%). The following analyses suggest an annually repeated seasonal progression of species assemblages: (i) the rank abundance of the 20 dominant species did not change significantly from year to year, (ii) variation in the density of the dominant species was primarily explained by intraannual rather than interannual variation, and (iii) multivariate analysis of the assemblage matrix identified five seasonal assemblages that occurred during all six years. We found that the timing and duration of each of these seasonal groups were correlated with two characteristics of the annual temperature cycle, magnitude (higher or lower temperature) and trajectory (increasing vs decreasing temperature). We suggest that the repeated occurrence of larval fish assemblages in temperate estuaries along the U.S. coast may, in part, be driven by local environmental processes.

scholarly journals RNA-seq Analysis of Salt-Stressed Versus Non Salt-Stressed Transcriptomes of Chenopodium quinoa Landrace R49

Genes ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1042 ◽  
Author(s):  
Karina B. Ruiz ◽  
Jonathan Maldonado ◽  
Stefania Biondi ◽  
Herman Silva
Keyword(s):  
Time Course ◽  
Average Length ◽  
Chenopodium Quinoa ◽  
Transcriptional Response ◽  
Sequencing Analysis ◽  
Rna Seq ◽  
Crop Species ◽  
Transcriptional Reprogramming ◽  
Transcriptomic Level ◽  
Shed Light

Quinoa (Chenopodium quinoa Willd.), a model halophytic crop species, was used to shed light on salt tolerance mechanisms at the transcriptomic level. An RNA-sequencing analysis of genotype R49 at an early vegetative stage was performed by Illumina paired-ends method comparing high salinity and control conditions in a time-course pot experiment. Genome-wide transcriptional salt-induced changes and expression profiling of relevant salt-responsive genes in plants treated or not with 300 mM NaCl were analyzed after 1 h and 5 days. We obtained up to 49 million pairs of short reads with an average length of 101 bp, identifying a total of 2416 differentially expressed genes (DEGs) based on the treatment and time of sampling. In salt-treated vs. control plants, the total number of up-regulated and down-regulated genes was 945 and 1471, respectively. The number of DEGs was higher at 5 days than at 1 h after salt treatment, as reflected in the number of transcription factors, which increased with time. We report a strong transcriptional reprogramming of genes involved in biological processes like oxidation-reduction, response to stress and response to abscisic acid (ABA), and cell wall organization. Transcript analyses by real-time RT- qPCR supported the RNA-seq results and shed light on the contribution of roots and shoots to the overall transcriptional response. In addition, it revealed a time-dependent response in the expression of the analyzed DEGs, including a quick (within 1 h) response for some genes, suggesting a “stress-anticipatory preparedness” in this highly salt-tolerant genotype.

scholarly journals Nonequilibrium thermodynamics of the Markovian Mpemba effect and its inverse

2017 ◽  
Vol 114 (20) ◽  
pp. 5083-5088 ◽  
Author(s):  
Zhiyue Lu ◽  
Oren Raz
Keyword(s):  
Nonequilibrium Thermodynamics ◽  
Underlying Mechanism ◽  
Ising Chain ◽  
Heating And Cooling ◽  
Inverse Effect ◽  
Diffusion Dynamics ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Model Diffusion ◽  
Shed Light

Under certain conditions, it takes a shorter time to cool a hot system than to cool the same system initiated at a lower temperature. This phenomenon—the “Mpemba effect”—was first observed in water and has recently been reported in other systems. Whereas several detail-dependent explanations were suggested for some of these observations, no common underlying mechanism is known. Using the theoretical framework of nonequilibrium thermodynamics, we present a widely applicable mechanism for a similar effect, the Markovian Mpemba effect, derive a sufficient condition for its appearance, and demonstrate it explicitly in three paradigmatic systems: the Ising model, diffusion dynamics, and a three-state system. In addition, we predict an inverse Markovian Mpemba effect in heating: Under proper conditions, a cold system can heat up faster than the same system initiated at a higher temperature. We numerically demonstrate that this inverse effect is expected in a 1D antiferromagnet nearest-neighbors interacting Ising chain in the presence of an external magnetic field. Our results shed light on the mechanism behind anomalous heating and cooling and suggest that it should be possible to observe these in a variety of systems.

scholarly journals Effect of External Calcium and of Temperature on Contraction in Snake Muscle Fibers

1974 ◽  
Vol 63 (4) ◽  
pp. 415-431 ◽  
Author(s):  
Hiroshi Washio
Keyword(s):  
Time Course ◽  
Contractile Response ◽  
Muscle Fibers ◽  
Outward Current ◽  
Bathing Solution ◽  
Minimum Duration ◽  
Delayed Rectification ◽  
Rate Of Recovery ◽  
Lower Temperature ◽  
External Calcium

The effect of external calcium and of temperature on the contractile responses has been studied in voltage clamped snake twitch muscle fibers. Increasing [Ca++]o from 0.2 to 7.0 mM raised contractile threshold by 15–20 mV, the latter coinciding with the appearance of delayed rectification. The duration of contracture, the rates of rise and decay of tension depended on the level of depolarization and [Ca++]o. The minimum duration of repolarization necessary to restore the contractile response was much shorter in high [Ca++]o. When the bathing solution was cooled to 10 from 20°C the time-course of contracture was markedly prolonged and the outward current was reduced without significant change in maximum tension. The threshold for contraction tended to be somewhat lower at the lower temperature. The contractile repriming was much slower at low temperature. However, reduction in temperature slowed the rate of recovery much less at low [Ca++]o than at normal [Ca++]o.

scholarly journals Differential susceptibility of neuronal neurotransmitter phenotypes to HHV6 infection

2021 ◽  
Author(s):  
E Bahramian ◽  
M Furr ◽  
JT Wu ◽  
RM Ceballos
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Nerve Cell ◽  
Time Course ◽  
Cell Types ◽  
Productive Infection ◽  
Virus Species ◽  
Cell Tropism ◽  
Human Neural Stem Cells ◽  
Sequence Identity

AbstractWithin the family Herpesviridae, sub-family β-herpesvirinae, and genus Roseolovirus, there are only three human herpesviruses that have been discovered and described: HHV-6A, HHV-6B, and HHV-7. Initially, HHV-6A and HHV-6B were considered to be simply two variants of the same virus (i.e., HHV6). Despite high overall genetic sequence identity (~90%), HHV-6A and HHV-6B are now recognized as two distinct viruses of the genus. Limited sequence identity (e.g., <70%) in key coding regions as well as significant differences in physiological and biochemical profiles (e.g., preferential use of different receptors for viral entry into susceptible hosts) underscore the conclusion that HHV-6A and HHV-6B are distinct virus species. Likewise, each virus appears to differentially contribute as putative etiologic agents to a variety of neurological disorders, including: multiple sclerosis, epilepsy, and chronic fatigue syndrome. Despite being implicated as causative agents in nervous system dysfunction, mechanisms of action and relative contributions of each virus to neural disorders remain elusive. Unresolved questions regarding: cell receptor use and binding affinity (i.e., CD49 versus CD134); cell tropism; the role of HHV-7 superinfection; and, relative virulence between HHV-6A versus HHV-6B – prevent a complete characterization. Although it has been demonstrated that both HHV-6A and HHV-6B can infect glia and, more recently, cerebellar Purkinje cells, cell tropism of HHV-6A versus HHV-6B for different nerve cell types remains vague. In this study, we demonstrate that both HHV-6A and HHV-6B can infect different nerve cell types (i.e., glia versus neurons) and different neuronal neurotransmitter phenotypes derived from the differentiation of human neural stem cells. We further show that both HHV-6A and HHV-6B induce cytopathic effects (CPEs) in susceptible nerve cells. However, the time-course and severity of CPEs appear to differ between HHV-6A versus HHV-6B infections and are dependent upon multiplicity of infection (MOI). As demonstrated by immunofluorescence, although both the HHV-6A and HHV-6B viruses productively infected VGluT1-containing cells (i.e., glutamatergic neurons) and dopamine-containing cells (i.e., dopaminergic neurons), neither HHV-6A nor HHV-6B challenge resulted in the productive infection of GAD67-containing cells (i.e., GABAergic cells). The reason underlying the apparent resistance of GABAergic cells to HHV-6A and HHV-6B infection remains unclear. Morphometric and image analyses of neurite extension and retraction dynamics as well as the time-course of cell aggregation phenomena (e.g., syncytia formation) during infection also indicate that HHV-6A induces more severe CPEs than HHV-6B at the same time-point and MOI. These data suggest that HHV-6A is more virulent than HHV-6B on susceptible human neural stem cells (HNSCs) differentiated into neuronal phenotypes, while neither virus is able to infect GABAergic cells. If these in vitro data hold in vivo, the inhibitory interneuron dysfunction hypothesis for HHV6-driven seizures may be ruled out as a potential mechanism for HHV6-induced epileptogenesis.

scholarly journals THE EFFECT OF TEMPERATURE, POTASSIUM, AND SODIUM ON THE CONDUCTANCE CHANGE ACCOMPANYING THE ACTION POTENTIAL IN THE SQUID GIANT AXON

1957 ◽  
Vol 41 (2) ◽  
pp. 333-342 ◽  
Author(s):  
E. Amatniek ◽  
W. Freygang ◽  
H. Grundfest ◽  
G. Kiebel ◽  
A. Shanes
Keyword(s):  
Time Course ◽  
Giant Axon ◽  
Membrane Resistance ◽  
Squid Giant Axon ◽  
Effect Of Temperature ◽  
Concentration Of Ions ◽  
Temperature Ranges ◽  
Conductance Changes ◽  
Lower Temperature ◽  
Possible Cause

Conductance changes associated with the response of the squid giant axon have been studied at two temperature ranges (26–27°C.; 9–10°C.) and with modified concentrations of sodium and potassium in the medium. The phase of "initial after-conductance," during which the membrane resistance increases above the resting value, is smaller at the lower temperature. At both temperature ranges it is diminished by doubling K+ in the medium and enhanced by removal of K+. Halving the Na+ of the medium also enhances this phase when K+ is absent, but not otherwise. The time course of the conductance changes alters in form with changes of the external medium. These changes indicate independent changes in the complex of ionic events associated with the response. The experiments therefore confirm the reality of the phase of increased membrane resistance. The magnitude of this change appears to be considerable and requires a transient decrease in the mobility and/or concentration of ions in the membrane. The possible cause of this decrease is discussed.

scholarly journals Musician Children Detect Pitch Violations in Both Music and Language Better than Nonmusician Children: Behavioral and Electrophysiological Approaches

2006 ◽  
Vol 18 (2) ◽  
pp. 199-211 ◽  
Author(s):  
Cyrille Magne ◽  
Daniele Schön ◽  
Mireille Besson
Keyword(s):  
Time Course ◽  
Musical Training ◽  
Neural Basis ◽  
Brain Potentials ◽  
Pitch Processing ◽  
Cognitive Domains ◽  
Music And Language ◽  
The Media ◽  
Shed Light ◽  
Better Than

The idea that extensive musical training can influence processing in cognitive domains other than music has received considerable attention from the educational system and the media. Here we analyzed behavioral data and recorded event-related brain potentials (ERPs) from 8-year-old children to test the hypothesis that musical training facilitates pitch processing not only in music but also in language. We used a parametric manipulation of pitch so that the final notes or words of musical phrases or sentences were congruous, weakly incongruous, or strongly incongruous. Musician children outperformed nonmusician children in the detection of the weak incongruity in both music and language. Moreover, the greatest differences in the ERPs of musician and nonmusician children were also found for the weak incongruity: whereas for musician children, early negative components developed in music and late positive components in language, no such components were found for nonmusician children. Finally, comparison of these results with previous ones from adults suggests that some aspects of pitch processing are in effect earlier in music than in language. Thus, the present results reveal positive transfer effects between cognitive domains and shed light on the time course and neural basis of the development of prosodic and melodic processing.

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