Flocculation in methanogens, a comparative study of Methanosarcina barken strains Jülich and Fusaro

1986 ◽  
Vol 32 (2) ◽  
pp. 137-144 ◽  
Author(s):  
P. A. Scherer ◽  
H. -P. Bochem ◽  
J. D. Davis ◽  
D. C. White
Keyword(s):  
Glucuronic Acid ◽  
Large Cell ◽  
Growth Conditions ◽  
Calcium Deficiency ◽  
Methanosarcina Barkeri ◽  
Uronic Acids ◽  
Poor Growth ◽  
Bread Crumb ◽  
Cell Aggregations

Two strains of Methanosarcina barkeri grown on methanol as substrate were investigated for their ability to aggregate: the new, flocculent strain Jülich formed stable flocs of several millimetres in diameter during rapid growth on a methanol-containing medium ("bread-crumb growth"). When observed with an electron microscope, the Jülich strain showed a unique parenchymatic texture with thick-walled cells inside a floc, and coccoidlike cells on the periphery. In contrast to the Jülich strain, the strain Fusaro grew on methanol in dispersed form, and generated macroscopically visible clumps only under poor growth conditions, induced, for example, by calcium deficiency. The formation of large cell aggregations of the Fusaro strain could also be induced during growth in the presence of 0.01% of the stain Calcofluor which is known to interact specifically with β-1,4 and β-1,3 glucan moieties. Sugar analyses revealed a different pattern for both strains: the exopolymer of the flocculent strain Jülich contained half the rhamnose, a third the fucose, equal amounts of mannose and glucose, but four times more glucuronic acid and arabinose than the strain Fusaro grown in the dispersed form. The high proportion of glucuronic acid in the exopolymer of the flocculating form is of particular interest because of the role of uronic acids in adhesion.

Role of the exosporial membrane in attachment and germination of C. sporogenes

1993 ◽  
Vol 51 ◽  
pp. 38-39
Author(s):  
B.J. Panessa-Warren ◽  
G.T. Tortora ◽  
J.B. Warren
Keyword(s):  
Enzymatic Degradation ◽  
Light Transmission ◽  
Extended Period ◽  
Growth Conditions ◽  
Clostridium Sporogenes ◽  
Radiation Chemical ◽  
Physical Trauma ◽  
Extended Contact ◽  
Cold Pressure

Some bacteria are capable of forming highly resistant spores when environmental conditions are not adequate for growth. Depending on the genus and species of the bacterium, these endospores are resistant in varying degrees to heat, cold, pressure, enzymatic degradation, ionizing radiation, chemical sterilants,physical trauma and organic solvents. The genus Clostridium, responsible for botulism poisoning, tetanus, gas gangrene and diarrhea in man, produces endospores which are highly resistant. Although some sporocides can kill Clostridial spores, the spores require extended contact with a sporocidal agent to achieve spore death. In most clinical situations, this extended period of treatment is not possible nor practical. This investigation examines Clostridium sporogenes endospores by light, transmission and scanning electron microscopy under various dormant and growth conditions, cataloging each stage in the germination and outgrowth process, and analyzing the role played by the exosporial membrane in the attachment and germination of the spore.

scholarly journals Ref2, a regulatory subunit of the yeast protein phosphatase 1, is a novel component of cation homoeostasis

2010 ◽  
Vol 426 (3) ◽  
pp. 355-364 ◽  
Author(s):  
Jofre Ferrer-Dalmau ◽  
Asier González ◽  
Maria Platara ◽  
Clara Navarrete ◽  
José L. Martínez ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Living Organism ◽  
Calcium Sensitivity ◽  
Growth Conditions ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit ◽  
Alkaline Ph ◽  
Yeast Protein ◽  
Increased Sensitivity

Maintenance of cation homoeostasis is a key process for any living organism. Specific mutations in Glc7, the essential catalytic subunit of yeast protein phosphatase 1, result in salt and alkaline pH sensitivity, suggesting a role for this protein in cation homoeostasis. We screened a collection of Glc7 regulatory subunit mutants for altered tolerance to diverse cations (sodium, lithium and calcium) and alkaline pH. Among 18 candidates, only deletion of REF2 (RNA end formation 2) yielded increased sensitivity to these conditions, as well as to diverse organic toxic cations. The Ref2F374A mutation, which renders it unable to bind Glc7, did not rescue the salt-related phenotypes of the ref2 strain, suggesting that Ref2 function in cation homoeostasis is mediated by Glc7. The ref2 deletion mutant displays a marked decrease in lithium efflux, which can be explained by the inability of these cells to fully induce the Na+-ATPase ENA1 gene. The effect of lack of Ref2 is additive to that of blockage of the calcineurin pathway and might disrupt multiple mechanisms controlling ENA1 expression. ref2 cells display a striking defect in vacuolar morphogenesis, which probably accounts for the increased calcium levels observed under standard growth conditions and the strong calcium sensitivity of this mutant. Remarkably, the evidence collected indicates that the role of Ref2 in cation homoeostasis may be unrelated to its previously identified function in the formation of mRNA via the APT (for associated with Pta1) complex.

scholarly journals MA23.07 Defining the Role of Adjuvant Therapy for Early Stage Large Cell Neuroendocrine Lung Cancer

2018 ◽  
Vol 13 (10) ◽  
pp. S440
Author(s):  
E. Wakeam ◽  
S. Stokes ◽  
A. Adibfar ◽  
N. Leighl ◽  
M. Giuliani ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Adjuvant Therapy ◽  
Early Stage ◽  
Large Cell

scholarly journals Strategies and Persuasive Appeals in the Public Service Messages about Health Issues on Pakistani Television Channels

2020 ◽  
Vol V (III) ◽  
pp. 54-72
Author(s):  
Qaisar Khan ◽  
Syed Inam Ur Rahman ◽  
Amna Nudrat
Keyword(s):  
Public Service ◽  
Heat Stroke ◽  
Calcium Deficiency ◽  
Health Issues ◽  
Major Health ◽  
The Public ◽  
Emergency Situations ◽  
Precautionary Measures ◽  
Aida Model

The study analyses strategies and persuasive appeals in the public service messages aired on Pakistani TV channels during 2016-2018, that measures the effects of PSMs on audience behaviour. The PSMs fails to deliver messages due to dissimilar socio-economic backdrop and scope of the audience understanding. The purposive sampling of six selected PSM is on the bases of health themed PSM’s. Objective is to investigate the characteristics of ads, role of the message, major health issues, sources of the message and appeals. The AIDA model, persuasion theory and social responsibility theory used to filter the textual analysis of the selected PSMs. It was found that the PSMs presented health issues while using celebrity endorsement and persuasive message appeals as persuasive techniques. The PSMs such as breast cancer persuaded women for self-care, calcium deficiency PSM to calcium intakes, heat stroke PSM to precautionary measures during emergency situations, the malnutrition PSM to women healthy diet during pregnancy. The study recommends that advertisers, producers and TV channels should adopt audience perception based important strategies for social welfare, while the state must promote them.

scholarly journals Hypothesis for the Role of Nutrient Starvation in Biofilm Detachment

2004 ◽  
Vol 70 (12) ◽  
pp. 7418-7425 ◽  
Author(s):  
Stephen M. Hunt ◽  
Erin M. Werner ◽  
Baochuan Huang ◽  
Martin A. Hamilton ◽  
Philip S. Stewart
Keyword(s):  
Continuous Flow ◽  
Large Cell ◽  
Nutrient Starvation ◽  
Flow Conditions ◽  
Cell Clusters ◽  
Theoretical Approaches ◽  
Biofilm Detachment ◽  
Pure Cultures ◽  
Potential Trigger

ABSTRACT A combination of experimental and theoretical approaches was used to investigate the role of nutrient starvation as a potential trigger for biofilm detachment. Experimental observations of detachment in a variety of biofilm systems were made with pure cultures of Pseudomonas aeruginosa. These observations indicated that biofilms grown under continuous-flow conditions detached after flow was stopped, that hollow cell clusters were sometimes observed in biofilms grown in flow cells, and that lysed cells were apparent in the internal strata of colony biofilms. When biofilms were nutrient starved under continuous-flow conditions, detachment still occurred, suggesting that starvation and not the accumulation of a metabolic product was responsible for triggering detachment in this particular system. A cellular automata computer model of biofilm dynamics was used to explore the starvation-dependent detachment mechanism. The model predicted biofilm structures and dynamics that were qualitatively similar to those observed experimentally. The predicted features included centrally located voids appearing in sufficiently large cell clusters, gradients in growth rate within these clusters, and the release of most of the biofilm with simulated stopped-flow conditions. The model was also able to predict biofilm sloughing resulting solely from this detachment mechanism. These results support the conjecture that nutrient starvation is an environmental cue for the release of microbes from a biofilm.

scholarly journals Increased Fitness of Pseudomonas fluorescens Pf0-1 Leucine Auxotrophs in Soil

2008 ◽  
Vol 74 (12) ◽  
pp. 3644-3651 ◽  
Author(s):  
Wook Kim ◽  
Stuart B. Levy
Keyword(s):  
Pseudomonas Fluorescens ◽  
Bacterial Genome ◽  
Physiological Role ◽  
Underlying Mechanism ◽  
Growth Conditions ◽  
Soil Environment ◽  
Fitness Advantage ◽  
Gene Structures

ABSTRACT The annotation process of a newly sequenced bacterial genome is largely based on algorithms derived from databases of previously defined RNA and protein-encoding gene structures. This process generally excludes the possibility that the two strands of a given stretch of DNA can each harbor a gene in an overlapping manner. While the presence of such structures in eukaryotic genomes is considered to be relatively common, their counterparts in prokaryotic genomes are just beginning to be recognized. Application of an in vivo expression technology has previously identified 22 discrete genetic loci in Pseudomonas fluorescens Pf0-1 that were specifically activated in the soil environment, of which 10 were present in an antisense orientation relative to previously annotated genes. This observation led to the hypothesis that the physiological role of overlapping genetic structures may be relevant to growth conditions outside artificial laboratory media. Here, we examined the role of one of the overlapping gene pairs, iiv19 and leuA2, in soil. Although iiv19 was previously demonstrated to be preferentially activated in the soil environment, its absence did not alter the ability of P. fluorescens to colonize or survive in soil. Surprisingly, the absence of the leuA2 gene conferred a fitness advantage in the soil environment when leucine was supplied exogenously. This effect was determined to be independent of the iiv19 gene, and further analyses revealed that amino acid antagonism was the underlying mechanism behind the observed fitness advantage of the bacterium in soil. Our findings provide a potential mechanism for the frequent occurrence of auxotrophic mutants of Pseudomonas spp. in the lungs of cystic fibrosis patients.

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