scholarly journals A Dictyostelium mutant deficient in severin, an F-actin fragmenting protein, shows normal motility and chemotaxis.

1989 ◽  
Vol 108 (3) ◽  
pp. 985-995 ◽  
Author(s):  
E André ◽  
M Brink ◽  
G Gerisch ◽  
G Isenberg ◽  
A Noegel ◽  
...  
Keyword(s):  
Cell Function ◽  
Polyclonal Antibodies ◽  
Deae Cellulose ◽  
Cell Movement ◽  
Processing System ◽  
Chemical Mutagenesis ◽  
Deficient Mutant ◽  
Wild Type ◽  
Coding Region ◽  
Mutant Cells

A severin deficient mutant of Dictyostelium discoideum has been isolated by the use of colony immunoblotting after chemical mutagenesis. In homogenates of wild-type cells, severin is easily detected as a very active F-actin fragmenting protein. Tests for severin in the mutant, HG1132, included viscometry for the assay of F-actin fragmentation in fractions from DEAE-cellulose columns, labeling of blots with monoclonal and polyclonal antibodies, and immunofluorescent-labeling of cryosections. Severin could not be detected in the mutant using these methods. The mutation in HG1132 is recessive and has been mapped to linkage group VII. The mutant failed to produce the normal severin mRNA, but small amounts of a transcript that was approximately 100 bases larger than the wild-type mRNA were detected in the mutant throughout all stages of development. On the DNA level a new Mbo II restriction site was found in the mutant within the coding region of the severin gene. The severin deficient mutant cells grew at an approximately normal rate, aggregated and formed fruiting bodies with viable spores. By the use of an image processing system, speed of cell movement, turning rates, and precision of chemotactic orientation in a stable gradient of cyclic AMP were quantitated, and no significant differences between wild-type and mutant cells were found. Thus, under the culture conditions used, severin proved to be neither essential for growth of D. discoideum nor for any cell function that is important for aggregation or later development.

Processing and Secretion of Lysosomal Acid ?-Glucosidase In Tetrahymena Wild Type and Secretion-Deficient Mutant Cells

1993 ◽  
Vol 40 (4) ◽  
pp. 515-520 ◽  
Author(s):  
YOSHIKO BANNO ◽  
YUKIO OKANO ◽  
KIYOSHI FURUKAWA ◽  
ARNO TIEDTKE ◽  
AKIRA KOBATA ◽  
...  
Keyword(s):  
Deficient Mutant ◽  
Wild Type ◽  
Lysosomal Acid ◽  
Mutant Cells

scholarly journals Gliding Mutants of Myxococcus xanthuswith High Reversal Frequencies and Small Displacements

1999 ◽  
Vol 181 (8) ◽  
pp. 2593-2601 ◽  
Author(s):  
Alfred M. Spormann ◽  
Dale Kaiser
Keyword(s):  
Single Cell ◽  
Cell Movement ◽  
Gliding Motility ◽  
Wild Type ◽  
Epistasis Analysis ◽  
Type Iv ◽  
Reversal Frequency ◽  
Order Of Magnitude ◽  
Dependent Cell ◽  
Mutant Cells

ABSTRACT Myxococcus xanthus cells move on a solid surface by gliding motility. Several genes required for gliding motility have been identified, including those of the A- and S-motility systems as well as the mgl and frz genes. However, the cellular defects in gliding movement in many of these mutants were unknown. We conducted quantitative, high-resolution single-cell motility assays and found that mutants defective inmglAB or in cglB, an A-motility gene, reversed the direction of gliding at frequencies which were more than 1 order of magnitude higher than that of wild type cells (2.9 min−1for ΔmglAB mutants and 2.7 min−1 forcglB mutants, compared to 0.17 min−1 for wild-type cells). The average gliding speed of ΔmglABmutant cells was 40% of that of wild-type cells (on average 1.9 μm/min for ΔmglAB mutants, compared to 4.4 μm/min for wild-type cells). The mglA-dependent reversals and gliding speeds were dependent on the level of intracellular MglA protein: mglB mutant cells, which contain only 15 to 20% of the wild-type level of MglA protein, glided with an average reversal frequency of about 1.8 min−1 and an average speed of 2.6 μm/min. These values range between those exhibited by wild-type cells and by ΔmglAB mutant cells. Epistasis analysis of frz mutants, which are defective in aggregation and in single-cell reversals, showed that a frzD mutation, but not a frzE mutation, partially suppressed themglA phenotype. In contrast to mgl mutants,cglB mutant cells were able to move with wild-type speeds only when in close proximity to each other. However, under those conditions, these mutant cells were found to glide less often with those speeds. By analyzing double mutants, the high reversing movements and gliding speeds of cglB cells were found to be strictly dependent on type IV pili, encoded by S-motility genes, whereas the high-reversal pattern ofmglAB cells was only partially reduced by apilR mutation. These results suggest that the MglA protein is required for both control of reversal frequency and gliding speed and that in the absence of A motility, type IV pilus-dependent cell movement includes reversals at high frequency. Furthermore, mglAB mutants behave as if they were severely defective in A motility but only partially defective in S motility.

scholarly journals Dictyostelium RasG Is Required for Normal Motility and Cytokinesis, But Not Growth

1997 ◽  
Vol 138 (3) ◽  
pp. 605-614 ◽  
Author(s):  
Richard I. Tuxworth ◽  
Janet L. Cheetham ◽  
Laura M. Machesky ◽  
George B. Spiegelmann ◽  
Gerald Weeks ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Cell Movement ◽  
Ras Proteins ◽  
Wild Type ◽  
Principal Role ◽  
Ras Protein ◽  
Wide Range ◽  
And Control ◽  
Mutant Cells ◽  
Lamellipodia Formation

RasG is the most abundant Ras protein in growing Dictyostelium cells and the closest relative of mammalian Ras proteins. We have generated null mutants in which expression of RasG is completely abolished. Unexpectedly, RasG− cells are able to grow at nearly wild-type rates. However, they exhibit defective cell movement and a wide range of defects in the control of the actin cytoskeleton, including a loss of cell polarity, absence of normal lamellipodia, formation of unusual small, punctate polymerized actin structures, and a large number of abnormally long filopodia. Despite their lack of polarity and abnormal cytoskeleton, mutant cells perform normal chemotaxis. However, rasG− cells are unable to perform normal cytokinesis, becoming multinucleate when grown in suspension culture. Taken together, these data suggest a principal role for RasG in coordination of cell movement and control of the cytoskeleton.

scholarly journals Transcriptomic analysis of astaxanthin hyper-producing Coelastrum sp. mutant obtained by chemical mutagenesis

2021 ◽  
Author(s):  
Ameerah Tharek ◽  
Shaza Eva Mohamad ◽  
Iwane Suzuki ◽  
Koji Iwamoto ◽  
Hirofumi Hara ◽  
...  
Keyword(s):  
Wild Type Strain ◽  
Beta Carotene ◽  
Transcriptomic Analysis ◽  
Chemical Mutagenesis ◽  
Wild Type ◽  
Genomic Information ◽  
Green Microalga ◽  
High Level ◽  
Mutant Cells ◽  
Β Carotene

AbstractA newly isolated green microalga, Coelastrum sp. has the capability to produce and accumulate astaxanthin under various stress conditions. At present, a mutant G1-C1 of Coelastrum sp. obtained through chemical mutagenesis using ethyl methane sulfonate displayed an improvement in astaxanthin accumulation, which was 2-fold higher than that of the wild-type. However, lack of genomic information limits the understanding of the molecular mechanism that leads to a high level of astaxanthin in the mutant G1-C1. In this study, transcriptome sequencing was performed to compare the transcriptome of astaxanthin hyper-producing mutant G1-C1 and wild-type of Coelastrum sp. with respect to astaxanthin biosynthesis. This is to clarify why the mutant produced higher astaxanthin yield compared to the wild-type strain. Based on the transcriptomic analysis, the differentially expressed genes involved in astaxanthin biosynthesis were significantly upregulated in the mutant G1-C1 of Coelastrum sp. Genes coding phytoene synthase, phytoene desaturase, ζ-carotene desaturase, and lycopene β-cyclase involved in β-carotene biosynthesis in the mutant cells were upregulated by 10-, 9.2-, 8.4-, and 8.7-fold, respectively. Genes coding beta-carotene ketolase and beta-carotene 3-hydroxylase involved in converting β-carotene into astaxanthin were upregulated by 7.8- and 8.0-fold, respectively. In contrast, the lycopene ε-cyclase gene was downregulated by 9.7-fold in mutant G1-C1. Together, these results contribute to higher astaxanthin accumulation in mutant G1-C1. Overall, the data in this study provided molecular insight for a better understanding of the differences in astaxanthin biosynthesis between the wild-type and mutant G1-C1 strains.

scholarly journals Disruption of the langerin/CD207 Gene Abolishes Birbeck Granules without a Marked Loss of Langerhans Cell Function

2005 ◽  
Vol 25 (1) ◽  
pp. 88-99 ◽  
Author(s):  
Adrien Kissenpfennig ◽  
Smina Aït-Yahia ◽  
Valérie Clair-Moninot ◽  
Hella Stössel ◽  
Edgar Badell ◽  
...  
Keyword(s):  
T Lymphocytes ◽  
Cell Function ◽  
Tumor Development ◽  
Similar Rate ◽  
Skin Tumor ◽  
Cell Surface Receptor ◽  
Chemical Mutagenesis ◽  
Wild Type ◽  
Normal Numbers ◽  
Surface Receptor

ABSTRACT Langerin is a C-type lectin expressed by a subset of dendritic leukocytes, the Langerhans cells (LC). Langerin is a cell surface receptor that induces the formation of an LC-specific organelle, the Birbeck granule (BG). We generated a langerin − / − mouse on a C57BL/6 background which did not display any macroscopic aberrant development. In the absence of langerin, LC were detected in normal numbers in the epidermis but the cells lacked BG. LC of langerin − / − mice did not present other phenotypic alterations compared to wild-type littermates. Functionally, the langerin − / − LC were able to capture antigen, to migrate towards skin draining lymph nodes, and to undergo phenotypic maturation. In addition, langerin − / − mice were not impaired in their capacity to process native OVA protein for I-A b -restricted presentation to CD4+ T lymphocytes or for H-2K b -restricted cross-presentation to CD8+ T lymphocytes. langerin − / − mice inoculated with mannosylated or skin-tropic microorganisms did not display an altered pathogen susceptibility. Finally, chemical mutagenesis resulted in a similar rate of skin tumor development in langerin − / − and wild-type mice. Overall, our data indicate that langerin and BG are dispensable for a number of LC functions. The langerin − / − C57BL/6 mouse should be a valuable model for further functional exploration of langerin and the role of BG.

scholarly journals Pneumolysin with Low Hemolytic Activity Confers an Early Growth Advantage to Streptococcus pneumoniae in the Blood

2011 ◽  
Vol 79 (10) ◽  
pp. 4122-4130 ◽  
Author(s):  
Richard M. Harvey ◽  
Abiodun D. Ogunniyi ◽  
Austen Y. Chen ◽  
James C. Paton
Keyword(s):  
Streptococcus Pneumoniae ◽  
Hemolytic Activity ◽  
Invasive Disease ◽  
Deficient Mutant ◽  
Wild Type ◽  
Content Type ◽  
Allelic Replacement ◽  
Serotype 1 ◽  
Important Virulence Factor ◽  
Mutant Cells

ABSTRACTStreptococcus pneumoniaeis a leading cause of human diseases such as pneumonia, bacteremia, meningitis, and otitis media. Pneumolysin (Ply) is an important virulence factor ofS. pneumoniaeand a promising future vaccine target. However, the expansion of clones carryingplyalleles with reduced hemolytic activity has been observed in serotypes associated with outbreaks of invasive disease and includes an allele identified in a highly virulent serotype 1 isolate (ply4496). The virulence of Ply-deficient andplyallelic-replacement derivatives ofS. pneumoniaeD39 was compared with that of wild-type D39. In addition, the protective immunogenicity of Ply against pneumococci with low versus high hemolytic activity was also investigated. Replacement of D39plywithply4496 resulted in a small but statistically significant reduction of virulence. However, both native Ply- and Ply4496-expressing strains were significantly more virulent than a Ply-deficient mutant. While the numbers of both Ply- and Ply4496-expressing isolate cells were higher in the blood than the numbers of Ply-deficient mutant cells, the growth of the Ply4496-expressing strain was superior to that of the wild type in the first 15 h postchallenge. Ply immunization provided protection regardless of the hemolytic activity of the challenge strain. In summary, we show that low-hemolytic-activity Ply alleles contribute to systemic virulence and may provide a survival advantage in the blood. Moreover, pneumococci expressing such alleles remain vulnerable to Ply-based vaccines.

Ultrastructure and Morphology of the Neurospora Crassa Cell Wall Mutants, Slime And Slime X, Using Tem and Sem

1976 ◽  
Vol 34 ◽  
pp. 54-55
Author(s):  
Karen S. Howard ◽  
H. D. Braymer ◽  
M. D. Socolofsky ◽  
S. A. Milligan
Keyword(s):  
Cell Wall ◽  
Neurospora Crassa ◽  
Wild Type ◽  
Morphological Comparison ◽  
Small Areas ◽  
Solid Media ◽  
Thin Sectioning ◽  
X Cells ◽  
Mutant Cells ◽  
Isolated Cell

The recently isolated cell wall mutant slime X of Neurospora crassa was prepared for ultrastructural and morphological comparison with the cell wall mutant slime. The purpose of this article is to discuss the methods of preparation for TEM and SEM observations, as well as to make a preliminary comparison of the two mutants.TEM: Cells of the slime mutant were prepared for thin sectioning by the method of Bigger, et al. Slime X cells were prepared in the same manner with the following two exceptions: the cells were embedded in 3% agar prior to fixation and the buffered solutions contained 5% sucrose throughout the procedure.SEM: Two methods were used to prepare mutant and wild type Neurospora for the SEM. First, single colonies of mutant cells and small areas of wild type hyphae were cut from solid media and fixed with OSO4 vapors similar to the procedure used by Harris, et al. with one alteration. The cell-containing agar blocks were dehydrated by immersion in 2,2-dimethoxypropane (DMP).

scholarly journals EPHA2-dependent outcompetition of KRASG12D mutant cells by wild-type neighbors in the adult pancreas

2021 ◽  
Author(s):  
William Hill ◽  
Andreas Zaragkoulias ◽  
Beatriz Salvador-Barbero ◽  
Geraint J. Parfitt ◽  
Markella Alatsatianos ◽  
...  
Keyword(s):  
Wild Type ◽  
Mutant Cells

scholarly journals Colony spreading of the gliding bacterium Flavobacterium johnsoniae in the absence of the motility adhesin SprB

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Keiko Sato ◽  
Masami Naya ◽  
Yuri Hatano ◽  
Yoshio Kondo ◽  
Mari Sato ◽  
...  
Keyword(s):  
Soft Agar ◽  
Gliding Motility ◽  
Wild Type ◽  
Initial Cell ◽  
Flavobacterium Johnsoniae ◽  
Seeking Behavior ◽  
Colony Spreading ◽  
Gliding Bacterium ◽  
Mutant Cells ◽  
Scanning Electron

AbstractColony spreading of Flavobacterium johnsoniae is shown to include gliding motility using the cell surface adhesin SprB, and is drastically affected by agar and glucose concentrations. Wild-type (WT) and ΔsprB mutant cells formed nonspreading colonies on soft agar, but spreading dendritic colonies on soft agar containing glucose. In the presence of glucose, an initial cell growth-dependent phase was followed by a secondary SprB-independent, gliding motility-dependent phase. The branching pattern of a ΔsprB colony was less complex than the pattern formed by the WT. Mesoscopic and microstructural information was obtained by atmospheric scanning electron microscopy (ASEM) and transmission EM, respectively. In the growth-dependent phase of WT colonies, dendritic tips spread rapidly by the movement of individual cells. In the following SprB-independent phase, leading tips were extended outwards by the movement of dynamic windmill-like rolling centers, and the lipoproteins were expressed more abundantly. Dark spots in WT cells during the growth-dependent spreading phase were not observed in the SprB-independent phase. Various mutations showed that the lipoproteins and the motility machinery were necessary for SprB-independent spreading. Overall, SprB-independent colony spreading is influenced by the lipoproteins, some of which are involved in the gliding machinery, and medium conditions, which together determine the nutrient-seeking behavior.

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