scholarly journals Seasonal Variation in Viral Infection Rates and Cell Sizes of Infected Prokaryotes in a Large and Deep Freshwater Lake (Lake Biwa, Japan)

2021 ◽  
Vol 12 ◽  
Author(s):  
Shang Shen ◽  
Yoshihisa Shimizu
Keyword(s):  
Surface Layer ◽  
Viral Infection ◽  
Cell Volume ◽  
Infection Rate ◽  
Lake Biwa ◽  
Freshwater Lake ◽  
Viral Abundance ◽  
Contact Rates ◽  
Viral Particles ◽  
The Impact

As viruses regulate prokaryotic abundance and the carbon cycle by infecting and lysing their prokaryotic hosts, the volume of infected prokaryotes is an important parameter for understanding the impact of viruses on aquatic environments. However, literature regarding the seasonal and spatial variations in the cell volume of infected prokaryotes is limited, despite the volume of the prokaryotic community varying dynamically with season and water column depth. Here, we conducted a field survey for two annual cycles in a large and deep freshwater lake (Lake Biwa, Japan), where large prokaryotes inhabit the deeper layer during the stratified period. We used transmission electron microscopy to reveal the seasonal and spatial variation in the frequency of viral infection and cell volume of infected prokaryotes. We found that the viral infection rate in the surface layer increased when estimated contact rates increased during the middle of the stratified period, whereas the infection rate in the deeper layer increased despite low estimated contact rates during the end of the stratified period. In addition, in the deeper layer, the fraction of large prokaryotes in the total and infected prokaryotic communities increased progressively while the number of intracellular viral particles increased. We suggest different ways in which the viral abundance is maintained in the two water layers. In the surface layer, it is speculated that viral abundance is supported by the high viral infection rate because of the high activity of prokaryotes, whereas in the deeper layer, it might be supported by the larger number of intracellular viral particles released from large prokaryotes. Moreover, large prokaryotes could contribute as important sources of organic substrates via viral lysis in the deeper layer, where labile dissolved organic matter is depleted.

Contribution of large bacteria to bacterial biomass in a deep freshwater lake (Lake Biwa, Japan)

2020 ◽  
Vol 85 ◽  
pp. 131-139
Author(s):  
S Shen ◽  
Y Shimizu
Keyword(s):  
Cell Volume ◽  
Bacterial Cell ◽  
Lake Biwa ◽  
Bacterial Biomass ◽  
Spatial Variations ◽  
Freshwater Lake ◽  
Heterotrophic Nanoflagellates ◽  
Bacterial Productivity ◽  
Transmission Electron ◽  
Seasonal And Spatial Variations

Despite the importance of bacterial cell volume in microbial ecology in aquatic environments, literature regarding the effects of seasonal and spatial variations on bacterial cell volume remains scarce. We used transmission electron microscopy to examine seasonal and spatial variations in bacterial cell size for 18 mo in 2 layers (epilimnion 0.5 m and hypolimnion 60 m) of Lake Biwa, Japan, a large and deep freshwater lake. During the stratified period, we found that the bacterial cell volume in the hypolimnion ranged from 0.017 to 0.12 µm3 (median), whereas that in the epilimnion was less variable (0.016 to 0.033 µm3, median) and much lower than that in the hypolimnion. Additionally, in the hypolimnion, cell volume during the stratified period was greater than that during the mixing period (up to 5.7-fold). These differences in cell volume resulted in comparable bacterial biomass in the hypolimnion and epilimnion, despite the fact that there was lower bacterial abundance in the hypolimnion than in the epilimnion. We also found that the biomass of larger bacteria, which are not likely to be grazed by heterotrophic nanoflagellates, increased in the hypolimnion during the stratified period. Our data suggest that estimation of carbon flux (e.g. bacterial productivity) needs to be interpreted cautiously when cell volume is used as a constant parametric value. In deep freshwater lakes, a difference in cell volume with seasonal and spatial variation may largely affect estimations.

scholarly journals Non-permissive SARS-CoV-2 infection in human neurospheres

2020 ◽  
Author(s):  
Carolina da S. G. Pedrosa ◽  
Livia Goto-Silva ◽  
Jairo R. Temerozo ◽  
Ismael C. Gomes ◽  
Leticia R. Q. Souza ◽  
...  
Keyword(s):  
Viral Infection ◽  
Inflammatory Responses ◽  
Cell Damage ◽  
Neural Tissue ◽  
Neural Cells ◽  
Neurological Manifestations ◽  
Viral Particles ◽  
Number Of Patients ◽  
The Central Nervous System ◽  
The Impact

AbstractCoronavirus disease 2019 (COVID-19) was initially described as a viral infection of the respiratory tract. It is now known, however, that several biological systems are also affected, including the central nervous system (CNS). Neurological manifestations such as stroke, encephalitis, and psychiatric conditions have been reported in COVID-19 patients, but the neurotropic potential of the virus is still debated. Herein, we sought to investigate SARS-CoV-2 infection in human neural cells. We demonstrated that SARS-CoV-2 infection of neural tissue is non-permissive, however it can elicit inflammatory response and cell damage. These findings are consistent with the hypothesis that most of the neural damage caused by SARS-CoV-2 infection is due to a systemic inflammation leading to indirect harmful effects on the CNS despite the absence of local viral replication.Author SummarySevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of Coronavirus disease 2019 (COVID-19). COVID-19 was initially described as a pulmonary disease, however, with an increased number of patients showing neurological manifestations, the SARS-CoV-2 neurotropism became an important issue. It is still unclear whether the new coronavirus causes direct damage to the neural tissue or if the neurological symptoms are the result of systemic vascular and inflammatory responses. Here, we investigated the consequences of the infection of human neurospheres by SARS-CoV-2. Despite SARS-CoV-2 RNA occurrence in the supernatant of neurospheres, we did not detect viral particles with infective capacity. Nevertheless, we observed some neuroinflammatory markers and cell cytotoxicity as a consequence of viral infection. Our study suggests that the impact of virus infection in the CNS is limited and massive damage may be caused by general inflammation.

scholarly journals The impact of quarantine on Covid-19 infections

2021 ◽  
Vol 10 (s1) ◽  
Author(s):  
Pablo Marshall
Keyword(s):  
Health System ◽  
Infection Rate ◽  
District Level ◽  
Infection Model ◽  
Social Distancing ◽  
Proposed Model ◽  
Lower Infection ◽  
The Impact ◽  
Lower Infection Rate ◽  
Over Time

Abstract Objectives: Coronavirushas had profound effects on people’s lives and the economy of many countries, generating controversy between the need to establish quarantines and other social distancing measures to protect people’s health and the need to reactivate the economy. This study proposes and applies a modification of the SIR infection model to describe the evolution of coronavirus infections and to measure the effect of quarantine on the number of people infected. Methods: Two hypotheses, not necessarily mutually exclusive, are proposed for the impact of quarantines. According to the first hypothesis, quarantine reduces the infection rate, delaying new infections over time without modifying the total number of people infected at the end of the wave. The second hypothesis establishes that quarantine reduces the population infected in the wave. The two hypotheses are tested with data for a sample of 10 districts in Santiago, Chile. Results: The results of applying the methodology show that the proposed model describes well the evolution of infections at the district level. The data shows evidence in favor of the first hypothesis, quarantine reduces the infection rate; and not in favor of the second hypothesis, that quarantine reduces the population infected. Districts of higher socio-economic levels have a lower infection rate, and quarantine is more effective. Conclusions: Quarantine, in most districts, does not reduce the total number of people infected in the wave; it only reduces the rate at which they are infected. The reduction in the infection rate avoids peaks that may collapse the health system.

scholarly journals Mining Google and Apple mobility data: temporal anatomy for COVID-19 social distancing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Corentin Cot ◽  
Giacomo Cacciapaglia ◽  
Francesco Sannino
Keyword(s):  
Infection Rate ◽  
The United States ◽  
Strong Decrease ◽  
Social Distancing ◽  
Mobility Data ◽  
Actual Measure ◽  
The Us ◽  
The Impact ◽  
Political Decisions ◽  
Mobility Reduction

AbstractWe employ the Google and Apple mobility data to identify, quantify and classify different degrees of social distancing and characterise their imprint on the first wave of the COVID-19 pandemic in Europe and in the United States. We identify the period of enacted social distancing via Google and Apple data, independently from the political decisions. Our analysis allows us to classify different shades of social distancing measures for the first wave of the pandemic. We observe a strong decrease in the infection rate occurring two to five weeks after the onset of mobility reduction. A universal time scale emerges, after which social distancing shows its impact. We further provide an actual measure of the impact of social distancing for each region, showing that the effect amounts to a reduction by 20–40% in the infection rate in Europe and 30–70% in the US.

scholarly journals The Effect of Vaccination Rates on the Infection of COVID-19 under the Vaccination Rate below the Herd Immunity Threshold

2021 ◽  
Vol 18 (14) ◽  
pp. 7491
Author(s):  
Yi-Tui Chen
Keyword(s):  
Infection Rate ◽  
Herd Immunity ◽  
The United States ◽  
Vaccination Rate ◽  
Infection Rates ◽  
Vaccination Rates ◽  
The United Kingdom ◽  
The World ◽  
Almost All ◽  
The Impact

Although vaccination is carried out worldwide, the vaccination rate varies greatly. As of 24 May 2021, in some countries, the proportion of the population fully vaccinated against COVID-19 has exceeded 50%, but in many countries, this proportion is still very low, less than 1%. This article aims to explore the impact of vaccination on the spread of the COVID-19 pandemic. As the herd immunity of almost all countries in the world has not been reached, several countries were selected as sample cases by employing the following criteria: more than 60 vaccine doses per 100 people and a population of more than one million people. In the end, a total of eight countries/regions were selected, including Israel, the UAE, Chile, the United Kingdom, the United States, Hungary, and Qatar. The results find that vaccination has a major impact on reducing infection rates in all countries. However, the infection rate after vaccination showed two trends. One is an inverted U-shaped trend, and the other is an L-shaped trend. For those countries with an inverted U-shaped trend, the infection rate begins to decline when the vaccination rate reaches 1.46–50.91 doses per 100 people.

scholarly journals Impact of Incorporating NIR Reflective Pigments in Finishing Coatings of ETICS

2021 ◽  
Vol 6 (6) ◽  
pp. 79
Author(s):  
Nuno M. M. Ramos ◽  
Joana Maia ◽  
Andrea R. Souza ◽  
Ricardo M. S. F. Almeida ◽  
Luís Silva
Keyword(s):  
Surface Layer ◽  
Surface Temperature ◽  
Near Infrared ◽  
Building Performance ◽  
Colour Difference ◽  
Colour Perception ◽  
Composite Systems ◽  
Solar Reflectance ◽  
Building Cooling ◽  
The Impact

Near-infrared (NIR) reflective materials are being developed for mitigating building cooling needs. Their use contributes to broadening the range of colours, responding to the urban aesthetic demand without compromising the building performance. Despite the increase in NIR reflective pigments investigation, there is still a knowledge gap in their applicability, impact, and durability in multilayer finishing coatings of External Thermal Insulation Composite Systems (ETICS). Hence, the main goal of this work consists of evaluating the impact of incorporating NIR reflective pigments (NRP) in the solar reflectance of the surface layer of ETICS, without affecting the colour perception, as well as their influence on the colour durability and surface temperature. As such, colour, solar reflectance, and surface temperature were monitored for 2 years in dark-coloured specimens of ETICS, with and without NRP and a primer layer. It was confirmed that the main contribution of NRP is the increase of solar reflectance and, consequently, the decrease in surface temperature, especially for high exterior temperatures (around 30 ºC). Moreover, these pigments highly increase the NIR reflectance without affecting the visible colour. In addition, they contribute to maintaining the colour characteristics. The application of primer increased the surface temperature, especially for higher exterior temperatures. However, it contributes to a lower colour difference and solar reflectance variation, which is an important achievement for durability purposes.

scholarly journals A Case of COVID-19-Related Thrombocytopenia and Leukopenia in an Adolescent with Mild Symptoms

Children ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 509
Author(s):  
Lydia Kossiva ◽  
Athanasios Thirios ◽  
Eleni Panagouli ◽  
Alexandros Panos ◽  
Stavroula Lampidi ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Viral Infection ◽  
Nasal Congestion ◽  
Pediatric Population ◽  
Clinical Manifestations ◽  
Bone Marrow Aspiration ◽  
White Blood Count ◽  
Chronic Obstructive ◽  
First Case ◽  
The Impact

Since the beginning of the COVID-19 pandemic, there have been numerous reports and reviews on the complications caused by the disease, analyzing the acute and chronic consequences. The main symptoms of SARS-CoV-2 are dry cough, fever, and fatigue. COVID-19 appears to affect all systems, including renal, cardiovascular, circulatory, and respiratory systems, causing chronic obstructive pulmonary disease. We report on a 14-year-old male adolescent, who presented with thrombocytopenia (platelet count 92 × 109 /L) and leukopenia (white blood count 4.2 × 103 /μL) that was observed two months ago. Ten days before the first blood test, a viral infection with nasal congestion and runny nose was reported, without other accompanying symptoms. Viral antibodies screening revealed positivity for all the three specific COVID-19 antibodies. Further haematological evaluation with bone marrow aspiration revealed non-specific dysplastic features of the red cell and megakaryocyte progenitors. Although haematological alterations due to COVID-19 infection are available from adult patients’ reports, the effect of COVID-19 infection in the pediatric population is underestimated and this is the first case with such haematological involvement. Noteworthy, in the current case, the impact of the COVID-19 infection was not related to the severity of the disease, as the symptoms were mild. In similar cases, bone marrow aspiration would not be performed as a part of routine work-up. Thus, it is important when evaluating pediatric patients with COVID-19 infection to search and report those alterations in order to better understand the impact and the spectrum of clinical manifestations of the specific viral infection in children and adolescents.

scholarly journals Springtime Upwelling and Its Formation Mechanism in Coastal Waters of Manaung Island, Myanmar

2020 ◽  
Vol 12 (22) ◽  
pp. 3777
Author(s):  
Yuhui Li ◽  
Yun Qiu ◽  
Jianyu Hu ◽  
Cherry Aung ◽  
Xinyu Lin ◽  
...  
Keyword(s):  
Surface Layer ◽  
Satellite Remote Sensing ◽  
Subsurface Layer ◽  
World Ocean ◽  
Remote Sensing Data ◽  
Remote Forcing ◽  
Forcing Mechanisms ◽  
World Ocean Atlas ◽  
The Impact ◽  
Local Wind Forcing

Multisource satellite remote sensing data and the World Ocean Atlas 2018 (WOA18) temperature and salinity dataset have been used to analyze the spatial distribution, variability and possible forcing mechanisms of the upwelling off Manaung Island, Myanmar. Signals of upwelling exist off the coasts of Manaung Island, in western Myanmar during spring. It appears in February, reaches its peak in March and decays in May. Low-temperature (<28.3 °C) and high-salinity (>31.8 psu) water at the surface of this upwelling zone is caused by the upwelling of seawater from a depth below 100 m. The impact of the upwelling on temperature is more significant in the subsurface layer than that in the surface layer. In contrast, the impact of the upwelling on salinity in the surface layer is more significant. Further research reveals that the remote forcing from the equator predominantly induces the evolution of the upwelling, while the local wind forcing also contributes to strengthen the intensity of the upwelling during spring.

scholarly journals Standardising intraoperative irrigation with 0.05% chlorhexidine gluconate in caesarean delivery to reduce surgical site infections: A single institution experience

2019 ◽  
Vol 30 (1-2) ◽  
pp. 24-33
Author(s):  
Theresa Mangold ◽  
Erin Kinzel Hamilton ◽  
Helen Boehm Johnson ◽  
Rene Perez
Keyword(s):  
Treatment Group ◽  
Surgical Site Infection ◽  
Infection Rate ◽  
Caesarean Delivery ◽  
Chlorhexidine Gluconate ◽  
Control Group ◽  
Antibiotic Administration ◽  
Site Infection ◽  
Infection Rates ◽  
The Impact

Background Surgical site infection is a significant cause of morbidity and mortality following caesarean delivery. Objective To determine whether standardising intraoperative irrigation with 0.05% chlorhexidine gluconate during caesarean delivery could decrease infection rates. Methods This was a process improvement project involving 742 women, 343 of whom received low-pressured 0.05% chlorhexidine gluconate irrigation during caesarean delivery over a one-year period. Infection rates were compared with a standard-of-care control group (399 women) undergoing caesarean delivery the preceding year. Results The treatment group infection rate met the study goal by achieving a lower infection rate than the control group, though this was not statistically significant. A significant interaction effect between irrigation with 0.05% chlorhexidine gluconate and antibiotic administration time existed, such that infection occurrence in the treatment group was not dependent on antibiotic timing, as opposed to the control group infection occurrence, which was dependent on antibiotic timing. Conclusion Intraoperative irrigation with 0.05% chlorhexidine gluconate during caesarean delivery did not statistically significantly reduce the rate of infections. It did render the impact of antibiotic administration timing irrelevant in prevention of surgical site infection. This suggests a role for 0.05% chlorhexidine gluconate irrigation in mitigating infection risk whether antibiotic prophylaxis timing is suboptimal or ideal.

scholarly journals Virus-mediated archaeal hecatomb in the deep seafloor

2016 ◽  
Vol 2 (10) ◽  
pp. e1600492 ◽  
Author(s):  
Roberto Danovaro ◽  
Antonio Dell’Anno ◽  
Cinzia Corinaldesi ◽  
Eugenio Rastelli ◽  
Ricardo Cavicchioli ◽  
...  
Keyword(s):  
Viral Infection ◽  
Deep Sea ◽  
Viral Infections ◽  
Biogeochemical Cycles ◽  
Global Scale ◽  
Viral Lysis ◽  
Group I ◽  
Global Biogeochemical Cycles ◽  
Bacterial Genes ◽  
The Impact

Viruses are the most abundant biological entities in the world’s oceans, and they play a crucial role in global biogeochemical cycles. In deep-sea ecosystems, archaea and bacteria drive major nutrient cycles, and viruses are largely responsible for their mortality, thereby exerting important controls on microbial dynamics. However, the relative impact of viruses on archaea compared to bacteria is unknown, limiting our understanding of the factors controlling the functioning of marine systems at a global scale. We evaluate the selectivity of viral infections by using several independent approaches, including an innovative molecular method based on the quantification of archaeal versus bacterial genes released by viral lysis. We provide evidence that, in all oceanic surface sediments (from 1000- to 10,000-m water depth), the impact of viral infection is higher on archaea than on bacteria. We also found that, within deep-sea benthic archaea, the impact of viruses was mainly directed at members of specific clades of Marine Group I Thaumarchaeota. Although archaea represent, on average, ~12% of the total cell abundance in the top 50 cm of sediment, virus-induced lysis of archaea accounts for up to one-third of the total microbial biomass killed, resulting in the release of ~0.3 to 0.5 gigatons of carbon per year globally. Our results indicate that viral infection represents a key mechanism controlling the turnover of archaea in surface deep-sea sediments. We conclude that interactions between archaea and their viruses might play a profound, previously underestimated role in the functioning of deep-sea ecosystems and in global biogeochemical cycles.

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