STUDIES ON THE RELATIONSHIP BETWEEN VIRUS AND HOST CELL

1951 ◽  
Vol 29 (3) ◽  
pp. 128-143 ◽  
Author(s):  
S. M. Lesley ◽  
R. C. French ◽  
A. F. Graham ◽  
C. E. van Rooyen
Keyword(s):  
Cell Surface ◽  
Host Cell ◽  
Trichloroacetic Acid ◽  
Experimental Results ◽  
Multiple Infection ◽  
Cell Ratio ◽  
E Coli ◽  
Soluble Phosphorus ◽  
Breakdown Curve ◽  
The Relationship

Infection of E. coli with P32 labelled T2r+ bacteriophage resulted in the con version of a part of the isotope to a form soluble in 5% trichloroacetic acid. This acid soluble phosphorus was used as a measure of the breakdown of the virus. When the phage to cell ratio was less than unity a two step breakdown curve was obtained corresponding to the two cycles of infection in this type of experi ment. The heights of the steps represented 5 and 32% breakdown, the second rise commencing after about 25 min. Multiple infection of cells yielded a curve which rose without inflection to about 23% breakdown at 20 min. after which there was little further increase. When the addition of radioactive phage was preceded by sufficient nonradioactive phage to infect most of the cells in the culture, the amount of breakdown of labelled virus increased to about 55% within 20 min. at which time breakdown practically ceased. Control experi ments indicated that dead phage in the labelled preparations contributed little to the acid soluble P32 fraction in these experiments and that the breakdown resulted from infection of the cells by virus. It is suggested that infection of cells by phage stimulates some mechanism whereby phage adsorbed to the cell at a later time is broken down extensively at the cell surface. The experimental results are interpreted in the light of this concept.

STUDIES ON THE RELATIONSHIP BETWEEN VIRUS AND HOST CELL

1951 ◽  
Vol 29 (3) ◽  
pp. 144-148
Author(s):  
R. C. French ◽  
S. M. Lesley ◽  
A. F. Graham ◽  
C. E. van Rooyen
Keyword(s):  
Host Cell ◽  
Trichloroacetic Acid ◽  
E Coli ◽  
Breakdown Mechanism ◽  
Previous Infection ◽  
Per Se ◽  
T7 Phage ◽  
The Relationship

Infection of E. coli with T2r, T4r+, T4r, T5, T6r+, or T6r phages induces the formation of a mechanism which extensively degrades P32 labelled T2r+ phage adsorbed to the cell shortly afterwards, about 50% of the P32 being converted to a form soluble in 5% trichloroacetic acid. Each of the above viruses is as effi cient in this respect as a preliminary infection with T2r+ phage itself. Previous infection of the cells with Tl, T3, or T7 phages does not stimulate this mechanism to break down labelled T2r+ virus. When Tl, T3, or T7 phage, then T2r+ phage, and finally P32 labelled T2r+ phage were added to cells, with an interval of several minutes between each addition, the results indicated that adsorption of T2r+ to the cell was not sufficient per se to stimulate the breakdown of labelled phage. Apparently actual infection of the cell by T2r+ virus was required before the breakdown mechanism was induced.

The relationship between health effects in triathletes and microbiological quality of freshwater

1995 ◽  
Vol 31 (5-6) ◽  
pp. 19-26 ◽  
Author(s):  
G. J. Medema ◽  
I. A. van Asperen ◽  
J. M. Klokman-Houweling ◽  
A. Nooitgedagt ◽  
M. J. W. van de Laar ◽  
...  
Keyword(s):  
Water Quality ◽  
Geometric Mean ◽  
Microbiological Quality ◽  
Quality Parameters ◽  
Health Complaints ◽  
E Coli ◽  
Thermotolerant Coliforms ◽  
Microbiological Water Quality ◽  
The Relationship ◽  
Faecal Streptococci

This pilot study was carried out to determine the relationship between microbiological water quality parameters and the occurrence of health complaints among triathletes. Data were collected at an Olympic distance triathlon (n=314) and a run-bike-run (n=81; controls for exposure to fresh water). At the time of the triathlon, the concentrations of Escherichia coli , thermotolerant coliforms, faecal streptococci, entero- and reoviruses, F-specific RNA phages, Salmonella, Campylobacter, Aeromonas, Plesiomonas shigelloides, Pseudomonas aeruginosa and Staphylococcus aureus were examined over the swimming course. Information on the occurrence of health complaints during the competition and in the week thereafter was collected through a written questionnaire. The results show that triathletes and run-bike-runners are comparable with respect to factors other than water exposure (age, sex, training history, physical stress, lower intestinal health complaints during the competition) that may influence the occurrence of health complaints in the week after the competition. Triathletes and run-bike-runners reported gastro-intestinal (7.7% vs 2.5%), respiratory (5.5% vs 3.7%), skin/mucosal (2.6% vs 1.2%), general (3.5% vs 1.2%) and total symptoms (14.8% vs 7.4%) in the week after the event. The health risks for triathletes for all symptom groups are not significantly higher than for run-bike-runners. The geometric mean concentration of faecal indicator bacteria is relatively low: E. coli 170/100 ml; faecal streptococci 13/100 ml, enteroviruses were present at concentrations of 0.1/l. The group of triathletes was homogeneusly and relatively intensely exposed to water; they all swam in the same body of water at the same time and 75% reported to have swallowed freshwater. It was concluded that this study design is suitable to study the relationship between health complaints and microbiological water quality. In the summers of 1993 and 1994, a study will be carried out concerning several run-bike-runs and triathlons in freshwaters of different quality.

The effect of type of water supply on water quality in a developing community in South Africa

1997 ◽  
Vol 35 (11-12) ◽  
pp. 35-40 ◽  
Author(s):  
B. Genthe ◽  
N. Strauss ◽  
J. Seager ◽  
C. Vundule ◽  
F. Maforah ◽  
...  
Keyword(s):  
Water Quality ◽  
Water Supply ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
E Coli ◽  
Guideline Values ◽  
Developing Communities ◽  
Quality Guideline ◽  
And Control ◽  
The Relationship

Efforts to provide water to developing communities in South Africa have resulted in various types of water supplies being used. This study examined the relationship between the type of water supply and the quality of water used. Source (communal taps, private outdoor and indoor taps) and point-of-use water samples were examined for heterotrophic plate counts (HPC), total and faecal coliforms, E. coli, and coliphages. Ten percent of samples were also analysed for enteric viruses, Giardia and Cryptosporidium. Approximately 320 households were included in a case-control study. In addition, a cross-sectional study was conducted. Both studies examined the relationship between different types of water facilities and diarrhoea among pre-school children. The source water was of good microbial quality, but water quality was found to have deteriorated significantly after handling and storage in both case and control households, exceeding drinking water quality guideline values by 1-6 orders of magnitude. Coliphage counts were low for all water samples tested. Enteric viruses and Cryptosporidium oocysts were not detected. Giardia cysts were detected on one occasion in case and control in-house samples. Comparisons of whether in-house water, after handling and storage, complied with water quality guideline values demonstrated households using communal taps to have significantly poorer quality than households using private outdoor or indoor taps for HPC and E. coli (χ2 = 14.9, P = 0.001; χ2 = 6.6, P = 0.04 respectively). A similar trend (although not statistically significant) was observed for the other microbial indicators. The cross-sectional study demonstrated an apparent decrease in health risk associated with private outdoor taps in comparison to communal taps. This study suggests that a private outdoor tap is the minimum level of water supply in order to ensure the supply of safe water to developing communities.

Parasites and promiscuity: Acute disease salience leads to more restricted sexual attitudes

2021 ◽  
pp. 026540752110309
Author(s):  
James B. Moran ◽  
Nicholas Kerry ◽  
Jin X. Goh ◽  
Damian R. Murray
Keyword(s):  
Social Behavior ◽  
Sexual Attitudes ◽  
Experimental Manipulation ◽  
Sexual Relationships ◽  
Experimental Results ◽  
Acute Disease ◽  
Short Term ◽  
Attitudes And Behaviors ◽  
The Relationship ◽  
Sexual Promiscuity

How does disease threat influence sexual attitudes and behaviors? Although research on the influence of disease threat on social behavior has grown considerably, the relationship between perceived disease threat and sexual attitudes remains unclear. The current preregistered study (analyzed N = 510), investigated how experimental reminders of disease threat influence attitudes and anticipated future behaviors pertaining to short-term sexual relationships, using an ecologically valid disease prime. The central preregistered prediction was that experimental manipulation of disease threat would lead to less favorable attitudes and inclinations toward sexual promiscuity. Results were consistent with this preregistered prediction, relative to both a neutral control condition and a non-disease threat condition. These experimental results were buttressed by the finding that dispositional variation in worry about disease threat predicted less favorable attitudes and inclinations toward short-term sexual relationships. This study represents the first preregistered investigation of the implications of acute disease threat for sexual attitudes.

scholarly journals A Single-Pass Type I Membrane Protein from the Apicomplexan Parasite Cryptosporidium parvum with Nanomolar Binding Affinity to Host Cell Surface

2021 ◽  
Vol 9 (5) ◽  
pp. 1015
Author(s):  
Tianyu Zhang ◽  
Xin Gao ◽  
Dongqiang Wang ◽  
Jixue Zhao ◽  
Nan Zhang ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Cell Surface ◽  
Host Cell ◽  
Binding Affinity ◽  
Cryptosporidium Parvum ◽  
Host Cells ◽  
Watery Diarrhea ◽  
Type I ◽  
Single Pass ◽  
Host Cell Surface

Cryptosporidium parvum is a globally recognized zoonotic parasite of medical and veterinary importance. This parasite mainly infects intestinal epithelial cells and causes mild to severe watery diarrhea that could be deadly in patients with weakened or defect immunity. However, its molecular interactions with hosts and pathogenesis, an important part in adaptation of parasitic lifestyle, remain poorly understood. Here we report the identification and characterization of a C. parvum T-cell immunomodulatory protein homolog (CpTIPH). CpTIPH is a 901-aa single-pass type I membrane protein encoded by cgd5_830 gene that also contains a short Vibrio, Colwellia, Bradyrhizobium and Shewanella (VCBS) repeat and relatively long integrin alpha (ITGA) N-terminus domain. Immunofluorescence assay confirmed the location of CpTIPH on the cell surface of C. parvum sporozoites. In congruence with the presence of VCBS repeat and ITGA domain, CpTIPH displayed high, nanomolar binding affinity to host cell surface (i.e., Kd(App) at 16.2 to 44.7 nM on fixed HCT-8 and CHO-K1 cells, respectively). The involvement of CpTIPH in the parasite invasion is partly supported by experiments showing that an anti-CpTIPH antibody could partially block the invasion of C. parvum sporozoites into host cells. These observations provide a strong basis for further investigation of the roles of CpTIPH in parasite-host cell interactions.

Fe(iii)-complex mediated bacterial cell surface immobilization of eGFP and enzymes

2021 ◽  
Author(s):  
Lilin Feng ◽  
Liang Gao ◽  
Daniel F. Sauer ◽  
Yu Ji ◽  
Haiyang Cui ◽  
...  
Keyword(s):  
Cell Surface ◽  
Bacterial Cell ◽  
Surface Immobilization ◽  
E Coli ◽  
Bacterial Cell Surface ◽  
Reversible Method

A facile and reversible method to immobilize His6-tagged proteins on the E. coli cell surface through the formation of an Fe(iii)-complex.

scholarly journals Exploring the taxonomical and functional profile of As Burgas hot spring focusing on thermostable β-galactosidases

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
María-Eugenia DeCastro ◽  
Michael P. Doane ◽  
Elizabeth Ann Dinsdale ◽  
Esther Rodríguez-Belmonte ◽  
María-Isabel González-Siso
Keyword(s):  
Microbial Community ◽  
Hot Spring ◽  
Functional Characterization ◽  
Tca Cycle ◽  
Maximal Activity ◽  
Sulfur Cycle ◽  
E Coli ◽  
Complex Microbial Community ◽  
Relationship Of ◽  
The Relationship

AbstractIn the present study we investigate the microbial community inhabiting As Burgas geothermal spring, located in Ourense (Galicia, Spain). The approximately 23 Gbp of Illumina sequences generated for each replicate revealed a complex microbial community dominated by Bacteria in which Proteobacteria and Aquificae were the two prevalent phyla. An association between the two most prevalent genera, Thermus and Hydrogenobacter, was suggested by the relationship of their metabolism. The high relative abundance of sequences involved in the Calvin–Benson cycle and the reductive TCA cycle unveils the dominance of an autotrophic population. Important pathways from the nitrogen and sulfur cycle are potentially taking place in As Burgas hot spring. In the assembled reads, two complete ORFs matching GH2 beta-galactosidases were found. To assess their functional characterization, the two ORFs were cloned and overexpressed in E. coli. The pTsbg enzyme had activity towards o-Nitrophenyl-β-d-galactopyranoside (ONPG) and p-Nitrophenyl-β-d-fucopyranoside, with high thermal stability and showing maximal activity at 85 °C and pH 6, nevertheless the enzyme failed to hydrolyze lactose. The other enzyme, Tsbg, was unable to hydrolyze even ONPG or lactose. This finding highlights the challenge of finding novel active enzymes based only on their sequence.

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