scholarly journals MACROMOLECULAR SYNTHESES RELATED TO THE REPRODUCTIVE CYST OF TETRAHYMENA PATULA

1973 ◽  
Vol 59 (3) ◽  
pp. 615-623 ◽  
Author(s):  
P. R. Gabe ◽  
L. E. de Bault
Keyword(s):  
Protein Synthesis ◽  
Dna Synthesis ◽  
Generation Time ◽  
Rna Synthesis ◽  
Culture Medium ◽  
Tritiated Thymidine ◽  
Growth Cycle ◽  
The Third ◽  
Rna And Protein Synthesis ◽  
The Mean

Macromolecular syntheses in encysted Tetrahymena patula were studied using Feulgen fluorescence cytophotometry, autoradiography, and inhibitors of RNA and protein synthesis. Cycloheximide significantly depressed protein synthesis and D-actinomycin effectively blocked RNA synthesis. Under these conditions, the cells within the cyst were unable to divide. Both cytophotometric measurements and autoradiographic data with tritiated thymidine show that DNA synthesis does not occur during the encystment divisions. Excysted cells placed in nutrient broth medium showed a prolonged generation time after the first cell growth cycle, and by the third generation the mean DNA content per cell was almost triple that of starved excysted cells. These findings indicate that (a) the encystment divisions require RNA and protein synthesis, which are apparently effected through turnover, (b) the encystment division cycles occur in the absence of DNA synthesis, and (c) excysted cells placed in culture medium may go through more than one DNA replication per cell cycle.

scholarly journals SYNTHETIC ACTIVITIES DURING SPERMATOGENESIS IN THE LOCUST

1965 ◽  
Vol 25 (2) ◽  
pp. 387-395 ◽  
Author(s):  
Nirmal K. Das ◽  
Elsie P. Siegel ◽  
Max Alfert
Keyword(s):  
Protein Synthesis ◽  
Nucleic Acid ◽  
Dna Synthesis ◽  
X Chromosome ◽  
Rna Synthesis ◽  
Schistocerca Gregaria ◽  
Tritiated Thymidine ◽  
Chromatin Condensation ◽  
Chromosome Condensation ◽  
Meiotic Cycle

Isolated testes of the locust Schistocerca gregaria were immersed in solutions of tritiated thymidine, cytidine, uridine, or arginine for short periods to study nucleic acid and protein synthesis during spermatogenesis. DNA synthesis in this tissue is completed prior to initiation of meiosis. Protein synthesis continues throughout the whole meiotic cycle as well as during spermatid development. Meiotic cells, except those in metaphase through early telophase, and early spermatids are also actively synthesizing RNA. The heteropycnotic X-chromosome does not produce RNA at any stage of spermatogenesis. The rates of protein and particularly RNA synthesis decrease as chromosome condensation progresses. Depression of RNA synthesis, however, is not always accompanied by cytologically detectable condensation of chromatin, since very little or no RNA is synthesized in spermatids in which chromatin condensation has barely begun.

FEMALE ENDOCRINE CONTROL MECHANISMS DURING THE NEONATAL PERIOD

1972 ◽  
Vol 70 (2) ◽  
pp. 396-408 ◽  
Author(s):  
K.-D. Schulz ◽  
H. Haarmann ◽  
A. Harland
Keyword(s):  
Protein Synthesis ◽  
Reproductive System ◽  
Rna Synthesis ◽  
Neonatal Period ◽  
High Dose ◽  
Female Reproductive System ◽  
Endocrine Control ◽  
Hypothalamic Region ◽  
Rna And Protein Synthesis ◽  
Physiological Dose

ABSTRACT The present investigation deals with the oestrogen-sensitivity of the female reproductive system during the neonatal period. Newborn female guinea pigs were used as test animals. At different times after a single subcutaneous injection of a physiological dose of 0.1 μg or an unphysiologically high dose of 10 μg 17β-oestradiol/100 g body weight, the RNA- and protein-synthesis was examined in the hypothalamic region, pituitary, cerebral cortex, liver, adrenal gland, ovary and uterus. With a physiological dose an increase in organ weight, protein content, RNA-and protein-synthesis was found only in the uterus. These alterations turned out to be dose-dependent. In addition to the findings in the uterus an inhibition of the aminoacid incorporation rate occurred in the liver following the injection of the high oestradiol dose. As early as 1 hour after the administration of 0.1 μg 17β-oestradiol an almost 100% increase in uterine protein synthesis was detectable. This result demonstrates a high oestrogen-sensitivity of this organ during the neonatal period. All the other organs of the female reproductive system such as the hypothalamus, pituitary and ovary did not show any oestrogen response. Therefore the functional immaturity of the uterus during post partem life is not the result of a deficient hormone sensitivity but is correlated with the absence of a sufficient hormonal stimulus at this time. The investigation on the effects of actinomycin resulted in different reactions in the uterus and liver. In contrast to the liver a paradoxical actinomycin effect was found in the uterus after treatment with actinomycin alone. This effect is characterized by a small inhibition of RNA-synthesis and a 50% increase in protein synthesis. The treatment of the newborn test animals with actinomycin and 17β-oestradiol together abolished the oestrogen-induced stimulation of the uterine RNA-and protein-synthesis. Consequently, the effect of oestrogens during the neonatal period is also connected with the formation of new proteins via an increased DNA-directed RNA-synthesis.

scholarly journals A Synthetic Congener Modeled on a Microbicidal Domain of Thrombin- Induced Platelet Microbicidal Protein 1 Recapitulates Staphylocidal Mechanisms of the Native Molecule

2006 ◽  
Vol 50 (11) ◽  
pp. 3786-3792 ◽  
Author(s):  
Yan Q. Xiong ◽  
Arnold S. Bayer ◽  
Lisa Elazegui ◽  
Michael R. Yeaman
Keyword(s):  
Protein Synthesis ◽  
Rna Synthesis ◽  
Membrane Permeabilization ◽  
Dna And Rna ◽  
Activated Platelets ◽  
Rna And Protein Synthesis ◽  
Dna And Rna Synthesis ◽  
Platelet Microbicidal Protein ◽  
Α Helix ◽  
Native Host

ABSTRACT Thrombin-induced platelet microbicidal protein 1 (tPMP-1) is a staphylocidal peptide released by activated platelets. This peptide initiates its microbicidal activity by membrane permeabilization, with ensuing inhibition of intracellular macromolecular synthesis. RP-1 is a synthetic congener modeled on the C-terminal microbicidal α-helix of tPMP-1. This study compared the staphylocidal mechanisms of RP-1 with those of tPMP-1, focusing on isogenic tPMP-1-susceptible (ISP479C) and -resistant (ISP479R) Staphylococcus aureus strains for the following quantitative evaluations: staphylocidal efficacy; comparative MIC; membrane permeabilization (MP) and depolarization; and DNA, RNA, and protein synthesis. Although the proteins had similar MICs, RP-1 caused significant killing of ISP479C (<50% survival), correlating with extensive MP (>95%) and inhibition of DNA and RNA synthesis (>90%), versus substantially reduced killing of ISP479R (>80% survival), with less MP (55%) and less inhibition of DNA or RNA synthesis (70 to 80%). Interestingly, RP-1-induced protein synthesis inhibition was equivalent in both strains. RP-1 did not depolarize the cell membrane and caused a relatively short postexposure growth inhibition. These data closely parallel those previously reported for tPMP-1 against this strain set and exemplify how synthetic molecules can be engineered to reflect structure-activity relationships of functional domains in native host defense effector molecules.

A comparison of the synthesis of DNA, RNA and proteins in the embryos of after-ripened and thermo- or FR-dormant Agrostemma githago L. seeds

1995 ◽  
Vol 5 (2) ◽  
pp. 87-97 ◽  
Author(s):  
U. Gerth ◽  
D. Bernhardt
Keyword(s):  
Protein Synthesis ◽  
Dna Synthesis ◽  
Rna Synthesis ◽  
Gradual Decrease ◽  
Two Dimensional ◽  
Dark Incubation ◽  
Low Level ◽  
Developmental Arrest ◽  
Stimulation Of

AbstractImbibed embryos of after-ripened and secondarily thermo- and FR-dormant Agrostemma githago seeds were investigated as to their ability to synthesize DNA, RNA and proteins with the aim of finding characteristic differences connected with the induction and maintenance of developmental arrest. A gradual decrease in DNA synthesis was observed during the induction of thermodormancy. However, DNA synthesis was stimulated up to that of embryos of 30–h-imbibed after-ripened seeds within 24 h approximately after transferring the thermodormant seeds into temperatures which normally allow germination. DNA synthesis of embryos of FR-dormant seeds remained constant at a relatively low level during 7 d FR and another 7 d dark incubation. RNA synthesis decreased to different extents during induction of thermo- and FR-dormancy when it was arrested at a relatively low level in seeds transferred to temperatures which normally allow germination. Processes leading to an increase in RNA synthesis such as in embryos of after-ripened seeds appeared to be quantitatively and/or qualitatively repressed. Interestingly, protein synthesis was extremely depressed during induction of thermodormancy whereas it was slightly stimulated during induction of FR-dormancy. Nevertheless two-dimensional protein PAGE revealed several polypeptides which were new, increased, decreased or not synthesized predominantly in axes of thermo- and FR-dormant seeds in comparison to germinating after-ripened seeds. It is suggested that a connection exists between these polypeptides and the repression of germination. After transferring seconarily dormant seeds to temperatures which normally allow germination, a temporary stimulation of protein synthesis could be observed in both cases.

Nucleic acid and protein synthesis and pattern regulation in hydra

Development ◽  
1969 ◽  
Vol 21 (1) ◽  
pp. 55-70
Author(s):  
S. G. Clarkson
Keyword(s):  
Protein Synthesis ◽  
Dna Synthesis ◽  
Experimental Approach ◽  
Direct Evidence ◽  
Animal Cells ◽  
Rna And Protein Synthesis ◽  
Metabolic Activities ◽  
Time Required ◽  
Pattern Regulation

In a previous paper (Clarkson, 1969) data were presented which indicate that hypostome determination is accompanied by a large and rapid burst of RNA synthesis, a slight stimulation of protein synthesis, and no increase in DNA synthesis. More direct evidence concerning the relative importance of these metabolic activities in hypostome determination is reported in this paper. The experimental approach made use of the transplantation test of Webster & Wolpert (1966) in conjunction with some inhibitors of DNA, RNA and protein synthesis, the rationale being that if these metabolic activities play important roles in the determination of the hypostome, then their inhibition would be expected to have severe effects on the time required for this process. Regarding the inhibitors, hydroxyurea (HU) inhibits DNA synthesis in a variety of animal cells without altering rates of formation of RNA or protein (Young & Hodas, 1964; Yarbro, Kennedy & Barnum, 1965; Schwartz, Garofalo, Sternberg & Philips, 1965).

Metabolic requirements for interactions between nuclear and cytoplasmic membranes in the repair of damaged Amoeba nuclei

1976 ◽  
Vol 21 (2) ◽  
pp. 291-302
Author(s):  
C.J. Flickinger
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Membrane Fusion ◽  
Energy Production ◽  
Rna Synthesis ◽  
Metabolic Inhibitors ◽  
Protein Synthesis Inhibitors ◽  
Nuclear Membranes ◽  
Cytoplasmic Membranes ◽  
Rna And Protein Synthesis

Amoeba nuclear envelopes were damaged using microsurgery, and metabolic requirements for the steps in their repair were studied, and my placing the cells in a solution containing one of several metabolic inhibitors. The first step in repair, the association of pieces of endoplasmic reticulum with holes in the nuclear membranes, appears to be a passive process since it was not affected by inhibitors of energy production, RNA synthesis, or protein synthesis. In contrast, fusion of pieces of endoplasmic reticulum with the nuclear membranes at the margins of the holes was blocked by KCN and dinitrophenol, indicating that membrane fusion requires energy derived from respiration, but RNA and protein synthesis inhibitors did not prevent fusion of pieces of endoplasmic reticulum with the nuclear membranes. The subsequent completion of repair and restoration of intact nuclear membranes was almost completely blocked by inhibitors of respiration, and it was reduced in the presence of actinomycin and emetine, suggesting that in addition to a requirement for energy, some later steps in the repair of the nuclear membranes require RNA and protein synthesis.

scholarly journals Mechanism for differential sensitivity of the chromosome and growth cycles of mammalian cells to the rate of protein synthesis.

1985 ◽  
Vol 5 (11) ◽  
pp. 2959-2966 ◽  
Author(s):  
R S Wu ◽  
W M Bonner
Keyword(s):  
Protein Synthesis ◽  
Dna Synthesis ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Growth Cycle ◽  
Differential Sensitivity ◽  
G1 Phase ◽  
Histone Protein ◽  
Chromosome Cycle ◽  
Compensation Mechanisms

It has been documented widely that when the generation times of eucaryotic cells are lengthened by slowing the rate of protein synthesis, the duration of the chromosome cycle (S, G2, and M phases) remains relatively invariant. Paradoxically, when the growth of exponentially growing cultures of CHO cells is partially inhibited with inhibitors of protein synthesis, the immediate effect is a proportionate reduction in the rate of total protein, histone protein, and DNA synthesis. However, on further investigation it was found that over the next 2 h the rates of histone protein and DNA synthesis recover, in some cases completely to the uninhibited rate, while the synthesis rates of other proteins do not recover. We called this process chromosome cycle compensation. The amount of compensation seen in CHO cell cultures can account quantitatively for the relative invariance in the length of the chromosome cycle (S, G2, and M phases) reported for these cells. The mechanism for this compensation involves a specific increase in the levels of histone mRNAs. An invariant chromosome cycle coupled with a lengthening growth cycle must result in a disproportionate lengthening of the G1 phase. Thus, these results suggest that chromosome cycle invariance may be due more to specific cellular compensation mechanisms rather than to the more usual interpretation involving a rate-limiting step for cell cycle progression in the G1 phase.

scholarly journals TIMING OF DNA SYNTHESIS IN THE MITOTIC CYCLE IN VITRO

1961 ◽  
Vol 9 (3) ◽  
pp. 509-518 ◽  
Author(s):  
Jesse E. Sisken ◽  
Riojun Kinosita
Keyword(s):  
Dna Synthesis ◽  
Generation Time ◽  
Mitotic Cycle ◽  
Tritiated Thymidine ◽  
Lung Cells ◽  
Human Amnion ◽  
Cells In Culture ◽  
Single Colony ◽  
Distribution Of Values

A study was made of the timing of DNA synthesis in the mitotic cycle under conditions where the average mitotic cycle of populations of human amnion and kitten lung cells in culture was variable. Three types of experiments were performed: (a) Autoradiographs were made of incorporated tritiated thymidine in cells whose mitotic histories were recorded microcinematographically allowing the measurement of telophase + G1 along with the total length of the mitotic cycle. (b) Measurement of the G2 + prophase part of the mitotic cycle was performed under various conditions by exposing cells to tritiated thymidine and observing the increase in labeled metaphases plus anaphases as a function of time. (c) The effect of a change in pH on parts of the mitotic cycle was tested by continuously photographing a single colony of cells first at pH 7.8 and then at pH 7.1. All of our data point to the same conclusion; namely, that within a population of cells with a given generation time, the length of each of the measurable parts of the mitotic cycle has a particular distribution of values and that, when there is a change in the generation time, under our conditions only the T + G1 distribution changes.

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