scholarly journals Kinetics of membrane internalization and recycling during pinocytosis in Dictyostelium discoideum.

1980 ◽  
Vol 77 (2) ◽  
pp. 1015-1019 ◽  
Author(s):  
L. Thilo ◽  
G. Vogel
Keyword(s):  
Dictyostelium Discoideum ◽  
Kinetics Of

scholarly journals Determinants of mRNA stability in Dictyostelium discoideum amoebae: differences in poly(A) tail length, ribosome loading, and mRNA size cannot account for the heterogeneity of mRNA decay rates.

1988 ◽  
Vol 8 (5) ◽  
pp. 1957-1969 ◽  
Author(s):  
R A Shapiro ◽  
D Herrick ◽  
R E Manrow ◽  
D Blinder ◽  
A Jacobson
Keyword(s):  
Steady State ◽  
Dictyostelium Discoideum ◽  
Mrna Decay ◽  
Decay Rates ◽  
Time Dependent ◽  
Translational Efficiency ◽  
Cdna Clones ◽  
Dependent Manner ◽  
Significant Difference ◽  
Kinetics Of

As an approach to understanding the structures and mechanisms which determine mRNA decay rates, we have cloned and begun to characterize cDNAs which encode mRNAs representative of the stability extremes in the poly(A)+ RNA population of Dictyostelium discoideum amoebae. The cDNA clones were identified in a screening procedure which was based on the occurrence of poly(A) shortening during mRNA aging. mRNA half-lives were determined by hybridization of poly(A)+ RNA, isolated from cells labeled in a 32PO4 pulse-chase, to dots of excess cloned DNA. Individual mRNAs decayed with unique first-order decay rates ranging from 0.9 to 9.6 h, indicating that the complex decay kinetics of total poly(A)+ RNA in D. discoideum amoebae reflect the sum of the decay rates of individual mRNAs. Using specific probes derived from these cDNA clones, we have compared the sizes, extents of ribosome loading, and poly(A) tail lengths of stable, moderately stable, and unstable mRNAs. We found (i) no correlation between mRNA size and decay rate; (ii) no significant difference in the number of ribosomes per unit length of stable versus unstable mRNAs, and (iii) a general inverse relationship between mRNA decay rates and poly(A) tail lengths. Collectively, these observations indicate that mRNA decay in D. discoideum amoebae cannot be explained in terms of random nucleolytic events. The possibility that specific 3'-structural determinants can confer mRNA instability is suggested by a comparison of the labeling and turnover kinetics of different actin mRNAs. A correlation was observed between the steady-state percentage of a given mRNA found in polysomes and its degree of instability; i.e., unstable mRNAs were more efficiently recruited into polysomes than stable mRNAs. Since stable mRNAs are, on average, "older" than unstable mRNAs, this correlation may reflect a translational role for mRNA modifications that change in a time-dependent manner. Our previous studies have demonstrated both a time-dependent shortening and a possible translational role for the 3' poly(A) tracts of mRNA. We suggest, therefore, that the observed differences in the translational efficiency of stable and unstable mRNAs may, in part, be attributable to differences in steady-state poly(A) tail lengths.

Isolation and Hybridization Kinetics of Messenger RNA from Dictyostelium discoideum

1972 ◽  
Vol 239 (95) ◽  
pp. 225-228 ◽  
Author(s):  
RICHARD A. FIRTEL ◽  
ALLAN JACOBSON ◽  
HARVEY F. LODISH
Keyword(s):  
Dictyostelium Discoideum ◽  
Messenger Rna ◽  
Kinetics Of

Differentiation of Dictyostelium discoideum mutant cells in a shaken suspension culture and the effect of cyclic AMP

1981 ◽  
Vol 51 (1) ◽  
pp. 131-142
Author(s):  
K. Abe ◽  
Y. Saga ◽  
H. Okada ◽  
K. Yanagisawa
Keyword(s):  
Cyclic Amp ◽  
Suspension Culture ◽  
Dictyostelium Discoideum ◽  
Solid Surface ◽  
Enzyme Activities ◽  
Parental Strain ◽  
Mutant Cell ◽  
Specific Activities ◽  
Mutant Cells ◽  
Kinetics Of

In Dictyostelium discoideum, 16 mutants in which cells differentiate into spores and stalk cells without normal morphogenesis were isolated. All these mutants are rapidly developing and capable of differentiating in a shaken suspension of phosphate buffer.The developmental kinetics of specific activities of enzymes in one of the mutants, HTY 1851, cultured in the suspension was compared with that in the parental strain, X2, developed on a solid surface. Most of the enzyme activities appeared much earlier and the peaks of the activities were lower in HTY1851 than X2, but the order or appearance of the activities was the same in both the strains cultured under the conditions described above. These results suggest that the biochemical steps in the development of the mutant in a shaken suspension are essentially the same as those of the parental strain X2 on a solid surface. It was also found that addition of cyclic AMP (2.5 X 10-5 M to 1 X 10-4 M) to the mutant cell suspension 6–8 h after the initiation of development induced an increase in the number of spores and the specific activities of some enzymes to values twice as high as those of an untreated control.

Influence of medium components on growth kinetics of Dictyostelium discoideum

2007 ◽  
Vol 24 (4) ◽  
pp. 491-499 ◽  
Author(s):  
Ying Hua Lu ◽  
Ying Wang ◽  
Xiao Xia Wu ◽  
Zhi Nan Xu ◽  
Ning He ◽  
...  
Keyword(s):  
Dictyostelium Discoideum ◽  
Growth Kinetics ◽  
Medium Components ◽  
Kinetics Of

scholarly journals Complete Sequences and Expression Kinetics of racG, racH, racI and racJ Genes in Dictyostelium discoideum.

2001 ◽  
Vol 24 (1) ◽  
pp. 84-87 ◽  
Author(s):  
Takako OKUWA ◽  
Takahiro MORIO ◽  
Tamao SAITO ◽  
Yukito MASAMUNE ◽  
Hiroo YASUKAWA
Keyword(s):  
Dictyostelium Discoideum ◽  
Complete Sequences ◽  
Kinetics Of ◽  
Expression Kinetics

scholarly journals Tip regeneration and positional information in the slug of Dictyostelium discoideum

Development ◽  
1983 ◽  
Vol 73 (1) ◽  
pp. 151-162
Author(s):  
Balakrishna L. Lokeshwar ◽  
Vidyanand Nanjundiah
Keyword(s):  
Dictyostelium Discoideum ◽  
Sudden Change ◽  
Positional Information ◽  
Anterior Portion ◽  
Regeneration Time ◽  
Cellular Slime ◽  
Rate Processes ◽  
Regeneration Times ◽  
Kinetics Of ◽  
Positional Value

We show in this paper that in the case of the slug of the cellular slime mould Dictyostelium discoideum the time which it takes for a new tip to regenerate at a given level can be used as a measure of positional information at that level. Our basic experiment consists ofamputating slugs at various distances from the existing tip and thereby inducing the regeneration of a fresh tip; the time needed for regeneration is estimated by two independent methods. An identical operation, when performed in the anterior portion of a previously cut slug, tells us how this position-dependent regeneration time adjusts to a sudden change in the size of the slug. The reasons which lead us to conclude that tip regeneration times are in one-to-one correspondence with positional information are as follows, (i) Depending on their positions, the cells in a slug take different times to regenerate a new tip following amputation; (ii) regeneration times are scaled in relation to the total length of the slug and increase monotonically with the length cut off; and (iii) as judged by the regeneration time, cells can assess and remember their positions relative to the length of the slug. Our results highlight the importance of two rate processes. One might think of the slower process as being related to the setting up of a system of positional information in the slug, and the faster process as being a reflection of the kinetics of the positional value changing locally till it reaches the level appropriate to a tip.

scholarly journals Characterization of colchicine-binding activity in Dictyostelium discoideum

1978 ◽  
Vol 169 (3) ◽  
pp. 499-504 ◽  
Author(s):  
P Cappuccinelli ◽  
B D Hames
Keyword(s):  
Dictyostelium Discoideum ◽  
High Speed ◽  
Binding Protein ◽  
Deae Cellulose ◽  
Binding Activity ◽  
Saturation Kinetics ◽  
Filter Assay ◽  
Kinetics Of ◽  
High Speed Supernatant

A colchicine-binding component was detected in vegetative amoebae of Dictyostelium discoideum by using a Millipore-filter assay. The colchicine-binding activity is temperature-and time-dependent, maximum binding occurring at 22-35 degrees C after 60 min incubation. Further increases in temperature are without effect on the extent of binding, but bound colchicine is released with increased time of incubation. Furthermore, colchicine-binding activity itself decreased in the high-speed supernatant from D. discoideum, with half the activity being lost in approx. 2.5h. Several lines of evidence, including the saturation kinetics of colchicine binding, enhancement of colchicine binding by tartrate, insensitivity to lumicolchicine, precipitation of the binding protein by vinblastine and behaviour of the binding protein on DEAE-cellulose and Sephadex resins, suggest that the colchicine-binding protein may be tubulin.

scholarly journals Identification of a Nucleic Acid-Regulated Cyclic GMP-Binding Activity in Dictyostelium Discoideum

1989 ◽  
Vol 92 (2) ◽  
pp. 291-301
Author(s):  
A. M. PARISSENTI ◽  
M. B. COUKELL
Keyword(s):  
Dictyostelium Discoideum ◽  
Cyclic Gmp ◽  
Specific Binding ◽  
Sodium Dodecyl ◽  
Binding Activity ◽  
Rnase A ◽  
Appreciable Effect ◽  
Cell Extracts ◽  
Type Activity ◽  
Kinetics Of

Using ion-exchange chromatography, we have identified and isolated two forms of a cyclic GMP-specific binding activity in filter-broken cell extracts of Dictyostelium discoideum. Upon addition of excess cold ligand, one form (S-type) released bound 3H-labelled cyclic GMP very slowly (t½ ≈ 68 min), while the other form (F-type) released the cyclic GMP in <1 min. After photoaffinity labelling with 32P-labelled cyclic GMP, both forms revealed a major 160x103Mr band (and a few bands of lower molecular weight) on autoradiograms of sodium dodecyl sulphate-polyacrylamide gels. Addition of 500 mM-NaCl to S-type activity converted the activity to a fast-dissociating form indistinguishable from F-type, and this conversion was reversed by dialysis. Salt treatment or dialysis had no appreciable effect on the association/dissociation kinetics of F-type activity. When crude S-type activity was heated (to destroy cyclic GMP binding) and then added to F-type activity, the latter activity acquired slow-dissociating properties identical to S-type. This result suggested that the cells possess a ‘factor’ that can dramatically alter binding properties of this cyclic GMP-binding protein. Crude preparations of this factor were by boiling or proteases, but were sensitive to RNase A. Further studies revealed that acids (in particular, DNA) could effectively mimic the factor in its ability to modulate the binding kinetics of the cyclic GMP-binding activity.

Sign in / Sign up

Export Citation Format

Share Document