Physical and physiological components of the graviresponses of wild-type and mutant Paramecium Tetraurelia

2000 ◽  
Vol 203 (6) ◽  
pp. 1059-1070 ◽  
Author(s):  
U. Nagel ◽  
H. Machemer
Keyword(s):  
Swimming Speed ◽  
Sedimentation Rates ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Centre Of Gravity ◽  
In The Wild ◽  
Type Population ◽  
G Value ◽  
Mutant Cells

Wild-type and the morphological mutant kin 241 of Paramecium tetraurelia showed improved orientation away from the centre of gravity (negative gravitaxis) when accelerations were increased from 1 to 7 g. Gravitaxis was more pronounced in the mutant. A correlation between the efficiency of orientation and the applied g value suggests a physical basis for gravitaxis. Transiently enhanced rates of reversal of the swimming direction coincided with transiently enhanced gravitaxis because reversals occurred more often in downward swimmers than in upward swimmers. The results provide evidence of a physiological modulation of gravitaxis by means of the randomizing effect of depolarization-dependent swimming reversals. Gravity bimodally altered propulsion rates of wild-type P. tetraurelia so that sedimentation was partly antagonized in upward and downward swimmers (negative gravikinesis). In the mutant, only increases in propulsion were observed, although the orientation-dependent sensitivity of the gravikinetic response was the same as in the wild-type population. Observed swimming speed and sedimentation rates in the wild-type and mutant cells were linearly related to acceleration, allowing the determination of gravikinesis as a linear (and so far non-saturating) function of gravity.

scholarly journals The Cloning and Molecular Analysis of pawn-B in Paramecium tetraurelia

Genetics ◽  
2000 ◽  
Vol 155 (3) ◽  
pp. 1105-1117 ◽  
Author(s):  
W John Haynes ◽  
Kit-Yin Ling ◽  
Robin R Preston ◽  
Yoshiro Saimi ◽  
Ching Kung
Keyword(s):  
Genomic Library ◽  
Open Reading Frame ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Rt Pcr ◽  
Reading Frame ◽  
Close Proximity ◽  
In The Wild ◽  
Dna Fragment ◽  
Alternative Sites

Abstract Pawn mutants of Paramecium tetraurelia lack a depolarization-activated Ca2+ current and do not swim backward. Using the method of microinjection and sorting a genomic library, we have cloned a DNA fragment that complements pawn-B (pwB/pwB). The minimal complementing fragment is a 798-bp open reading frame (ORF) that restores the Ca2+ current and the backward swimming when expressed. This ORF contains a 29-bp intron and is transcribed and translated. The translated product has two putative transmembrane domains but no clear matches in current databases. Mutations in the available pwB alleles were found within this ORF. The d4-95 and d4-96 alleles are single base substitutions, while d4-662 (previously pawn-D) harbors a 44-bp insertion that matches an internal eliminated sequence (IES) found in the wild-type germline DNA except for a single C-to-T transition. Northern hybridizations and RT-PCR indicate that d4-662 transcripts are rapidly degraded or not produced. A second 155-bp IES in the wild-type germline ORF excises at two alternative sites spanning three asparagine codons. The pwB ORF appears to be separated from a 5′ neighboring ORF by only 36 bp. The close proximity of the two ORFs and the location of the pwB protein as indicated by GFP-fusion constructs are discussed.

scholarly journals Structural determination of a 5-O-methyl-deaminated neuraminic acid (Kdn)-containing polysaccharide isolated from Sinorhizobium fredii

1998 ◽  
Vol 334 (3) ◽  
pp. 585-594 ◽  
Author(s):  
Antonio M. GIL-SERRANO ◽  
Miguel A. ÍGUEZ-CARVAJAL RODR ◽  
Pilar TEJERO-MATEO ◽  
José L. ESPARTERO ◽  
Jane THOMAS-OATES ◽  
...  
Keyword(s):  
Fast Atom Bombardment ◽  
Wild Type Strain ◽  
Auxotrophic Mutant ◽  
Neuraminic Acid ◽  
Wild Type ◽  
1H And 13C Nmr ◽  
One Dimensional ◽  
In The Wild ◽  
Fast Atom Bombardment Ms

The structure of a polysaccharide from Sinorhizobium frediiSVQ293, a thiamine auxotrophic mutant of S. fredii HH103, has been determined. This polysaccharide was isolated following the protocol for lipopolysaccharide extraction. On the basis of monosaccharide analysis, methylation analysis, fast atom bombardment MS, collision-induced dissociation tandem MS, one-dimensional 1H and 13C NMR and two-dimensional NMR experiments, the structure was shown to consist of the following trisaccharide repeating unit → 2)-α-d-Galp-(1 → 2)-β-d-Ribf-(1 → 9)-α-5-O-Me-Kdnp-(2 →, in which Kdn stands for deaminated neuraminic acid; 25% of the Kdn residues are not methylated. The structure of this polysaccharide is novel and this is the first report of the presence of Kdn in a rhizobial polysaccharide, as well as being the first structure described containing 5-O-Me-Kdn. This Kdn-containing polysaccharide is not present in the wild-type strain HH103, which produces a 3-deoxy-d-manno-2-octulosonic acid (Kdo)-rich polysaccharide. We conclude that it is likely that the appearance of this new Kdn-containing polysaccharide is a consequence of the mutation.

Enhanced sodium-dependent extrusion of magnesium in mutant cells established from a mouse renal tubular cell line

2005 ◽  
Vol 289 (4) ◽  
pp. F742-F748 ◽  
Author(s):  
Masaru Watanabe ◽  
Masato Konishi ◽  
Ichiro Ohkido ◽  
Senya Matsufuji
Keyword(s):  
Culture Media ◽  
Cell Types ◽  
Renal Tubular Cell ◽  
Wild Type ◽  
Tubular Cells ◽  
Renal Tubular Cells ◽  
In The Wild ◽  
Renal Tubular ◽  
Mutant Cells ◽  
Very High

To study the regulatory mechanisms of intracellular Mg2+ concentration ([Mg2+]i) in renal tubular cells as well as in other cell types, we established a mutant strain of mouse renal cortical tubular cells that can grow in culture media with very high extracellular Mg2+ concentrations ([Mg2+]o > 100 mM: 101Mg-tolerant cells). [Mg2+]i was measured with a fluorescent indicator furaptra (mag-fura 2) in wild-type and 101Mg-tolerant cells. The average level of [Mg2+]i in the 101Mg-tolerant cells was kept lower than that in the wild-type cells either at 51 mM or 1 mM [Mg2+]o. When [Mg2+]o was lowered from 51 to 1 mM, the decrease in [Mg2+]i was significantly faster in the 101Mg-tolerant cells than in the wild-type cells. These differences between the 101Mg-tolerant cells and the wild-type cells were abolished in the absence of extracellular Na+ or in the presence of imipramine, a known inhibitor of Na+/Mg2+ exchange. We conclude that Na+-dependent Mg2+ transport activity is enhanced in the 101Mg-tolerant cells. The enhanced Mg2+ extrusion may prevent [Mg2+]i increase to higher levels and may be responsible for the Mg2+ tolerance.

scholarly journals Macronuclear transformation with specific DNA fragments controls the content of the new macronuclear genome in Paramecium tetraurelia.

1991 ◽  
Vol 11 (2) ◽  
pp. 1133-1137 ◽  
Author(s):  
Y You ◽  
K Aufderheide ◽  
J Morand ◽  
K Rodkey ◽  
J Forney
Keyword(s):  
Cell Line ◽  
Dna Sequences ◽  
Mutant Cell ◽  
Restriction Pattern ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Coding Region ◽  
Cytoplasmic Factor ◽  
In The Wild ◽  
Dna Restriction

A previously isolated mutant cell line called d48 contains a complete copy of the A surface antigen gene in the micronuclear genome, but the gene is not incorporated into the macronucleus. Previous experiments have shown that a cytoplasmic factor made in the wild-type macronucleus can rescue the mutant. Recently, S. Koizumi and S. Kobayashi (Mol. Cell. Biol. 9:4398-4401, 1989) observed that injection of a plasmid containing the A gene into the d48 macronucleus rescued the cell line after autogamy. It is shown here that an 8.8-kb EcoRI fragment containing only a portion of the A gene coding region is sufficient for the rescue of d48. The inability of other A gene fragments to rescue the mutant shows that this effect is dependent upon specific Paramecium DNA sequences. Rescue results in restoration of the wild-type DNA restriction pattern in the macronucleus. These results are consistent with a model in which the macronuclear A locus normally makes an additional gene product that is required for correct processing of the micronuclear copy of the A gene.

scholarly journals Isolation of theCAR1Gene fromSaccharomyces cerevisiaeand Analysis of Its Expression

1982 ◽  
Vol 2 (12) ◽  
pp. 1514-1523 ◽  
Author(s):  
Roberta A. Sumrada ◽  
Terrance G. Cooper
Keyword(s):  
Nitrogen Source ◽  
Wild Type ◽  
Polyadenylated Rna ◽  
Regulatory Mutations ◽  
In The Wild ◽  
Steady State Levels ◽  
Nitrogen Repression ◽  
Dna Fragment ◽  
Cloned Gene ◽  
Mutant Cells

We isolated theCARIgene fromSaccharomyces cerevisiaeon a recombinant plasmid and localized it to a 1.58-kilobase DNA fragment. The cloned gene was used as a probe to analyze polyadenylated RNA derived from wild-type and mutant cells grown in the presence and absence of an inducer. Wild-type cells grown without the inducer contained very little polyadenylated RNA capable of hybridizing to the isolatedCAR1gene. A 1.25-kilobaseCAR1-specific RNA species was markedly increased, however, in wild-type cells grown in the presence of inducer and in constitutive, regulatory mutants grown without it. NoCAR1-specific RNA was observed when one class of constitutive mutant was grown in medium containing a good nitrogen source, such as asparagine. Two other mutants previously shown to be resistant to nitrogen repression contained large quantities ofCAR1RNA regardless of the nitrogen source in the medium. These data point to a qualitative correlation between the steady-state levels ofCAR1-specific, polyadenylated RNA and the degree of arginase induction and repression observed in the wild type and in strains believed to carry regulatory mutations. Therefore, they remain consistent with our earlier suggestion that arginase production is probably controlled at the level of gene expression.

scholarly journals Macronuclear transformation with specific DNA fragments controls the content of the new macronuclear genome in Paramecium tetraurelia

1991 ◽  
Vol 11 (2) ◽  
pp. 1133-1137
Author(s):  
Y You ◽  
K Aufderheide ◽  
J Morand ◽  
K Rodkey ◽  
J Forney
Keyword(s):  
Cell Line ◽  
Dna Sequences ◽  
Mutant Cell ◽  
Restriction Pattern ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Coding Region ◽  
Cytoplasmic Factor ◽  
In The Wild ◽  
Dna Restriction

A previously isolated mutant cell line called d48 contains a complete copy of the A surface antigen gene in the micronuclear genome, but the gene is not incorporated into the macronucleus. Previous experiments have shown that a cytoplasmic factor made in the wild-type macronucleus can rescue the mutant. Recently, S. Koizumi and S. Kobayashi (Mol. Cell. Biol. 9:4398-4401, 1989) observed that injection of a plasmid containing the A gene into the d48 macronucleus rescued the cell line after autogamy. It is shown here that an 8.8-kb EcoRI fragment containing only a portion of the A gene coding region is sufficient for the rescue of d48. The inability of other A gene fragments to rescue the mutant shows that this effect is dependent upon specific Paramecium DNA sequences. Rescue results in restoration of the wild-type DNA restriction pattern in the macronucleus. These results are consistent with a model in which the macronuclear A locus normally makes an additional gene product that is required for correct processing of the micronuclear copy of the A gene.

scholarly journals A temperature-sensitive mutation of the Schizosaccharomyces pombe gene nuc2+ that encodes a nuclear scaffold-like protein blocks spindle elongation in mitotic anaphase.

1988 ◽  
Vol 106 (4) ◽  
pp. 1171-1183 ◽  
Author(s):  
T Hirano ◽  
Y Hiraoka ◽  
M Yanagida
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Gradient Centrifugation ◽  
Metaphase Plate ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Wild Type ◽  
In The Wild ◽  
Spindle Elongation ◽  
Mutant Cells

A temperature-sensitive mutant nuc2-663 of the fission yeast Schizosaccharomyces pombe specifically blocks mitotic spindle elongation at restrictive temperature so that nuclei in arrested cells contain a short uniform spindle (approximately 3-micron long), which runs through a metaphase plate-like structure consisting of three condensed chromosomes. In the wild-type or in the mutant cells at permissive temperature, the spindle is fully extended approximately 15-micron long in anaphase. The nuc2' gene was cloned in a 2.4-kb genomic DNA fragment by transformation, and its complete nucleotide sequence was determined. Its coding region predicts a 665-residues internally repeating protein (76.250 mol wt). By immunoblots using anti-sera raised against lacZ-nuc2+ fused proteins, a polypeptide (designated p67; 67,000 mol wt) encoded by nuc2+ is detected in the wild-type S. pombe extracts; the amount of p67 is greatly increased when multi-copy or high-expression plasmids carrying the nuc2+ gene are introduced into the S. pombe cells. Cellular fractionation and Percoll gradient centrifugation combined with immunoblotting show that p67 cofractionates with nuclei and is enriched in resistant structure that is insoluble in 2 M NaCl, 25 mM lithium 3,5'-diiodosalicylate, and 1% Triton but is soluble in 8 M urea. In nuc2 mutant cells, however, soluble p76, perhaps an unprocessed precursor, accumulates in addition to insoluble p67. The role of nuc2+ gene may be to interconnect nuclear and cytoskeletal functions in chromosome separation.

The in vivo role of annexin VII (synexin): characterization of an annexin VII-deficient Dictyostelium mutant indicates an involvement in Ca(2+)-regulated processes

1995 ◽  
Vol 108 (5) ◽  
pp. 2065-2076 ◽  
Author(s):  
V. Doring ◽  
F. Veretout ◽  
R. Albrecht ◽  
B. Muhlbauer ◽  
C. Schlatterer ◽  
...  
Keyword(s):  
Developmental Cycle ◽  
Cell Fractionation ◽  
Wild Type ◽  
Camp Phosphodiesterase ◽  
In The Wild ◽  
Extracellular Camp ◽  
Mutant Cells

Dictyostelium discoideum cells harbor two annexin VII isoforms of 47 and 51 kDa which are present throughout development. In immunofluorescence and cell fractionation studies annexin VII was found in the cytoplasm and on the plasma membrane. In gene disruption mutants lacking both annexin VII isoforms growth, pinocytosis, phagocytosis, chemotaxis and motility were not significantly impaired under routine laboratory conditions, and the cells were able to complete the developmental cycle on bacterial plates. On non-nutrient agar plates development was delayed by three to four hours and a significant number of aggregates was no longer able to form fruiting bodies. Exocytosis as determined by measuring extracellular cAMP phosphodiesterase, alpha-fucosidase and alpha-mannosidase activity was unaltered, the total amounts of these enzymes were however lower in the mutant than in the wild type. The mutant cells were markedly impaired when they were exposed to low Ca2+ concentrations by adding EGTA to the nutrient medium. Under these conditions growth, motility and chemotaxis were severely affected. The Ca2+ concentrations were similar in mutant and wild-type cells both under normal and Ca2+ limiting conditions; however, the distribution was altered under low Ca2+ conditions in SYN-cells. The data suggest that annexin VII is not required for membrane fusion events but rather contributes to proper Ca2+ homeostasis in the cell.

scholarly journals The Clp Proteases of Bacillus subtilisAre Directly Involved in Degradation of Misfolded Proteins

2000 ◽  
Vol 182 (11) ◽  
pp. 3259-3265 ◽  
Author(s):  
Elke Krüger ◽  
Elke Witt ◽  
Steffen Ohlmeier ◽  
Renate Hanschke ◽  
Michael Hecker
Keyword(s):  
Immunogold Labeling ◽  
Misfolded Proteins ◽  
Turnover Rates ◽  
Wild Type ◽  
Heat Stress Response ◽  
Clp Proteases ◽  
In The Wild ◽  
Ultrathin Cryosections ◽  
Mutant Cells

ABSTRACT The presence of the heat stress response-related ATPases ClpC and ClpX or the peptidase ClpP in the cell is crucial for tolerance of many forms of stress in Bacillus subtilis. Assays for detection of defects in protein degradation suggest that ClpC, ClpP, and ClpX participate directly in overall proteolysis of misfolded proteins. Turnover rates for abnormal puromycyl peptides are significantly decreased in clpC, clpP, and clpXmutant cells. Electron-dense aggregates, most likely due to the accumulation of misfolded proteins, were noticed in studies of ultrathin cryosections in clpC and clpP mutant cells even under nonstress conditions. In contrast, in the wild type orclpX mutants such aggregates could only be observed after heat shock. This phenomenon supports the assumption thatclpC and clpP mutants are deficient in the ability to solubilize or degrade damaged and aggregated proteins, the accumulation of which is toxic for the cell. By using immunogold labeling with antibodies raised against ClpC, ClpP, and ClpX, the Clp proteins were localized in these aggregates, showing that the Clp proteins act at this level in vivo.

Sign in / Sign up

Export Citation Format

Share Document