Total Ribonucleic Acid Content Research Articles

Transformation of Rana tigrina during Progressive Metamorphosis

We determined the kinetics of metamorphosis, apoptosis, and tail regression in Rana tigrina. Acid phosphatase activity (µMole Pi.hr-1.tail-1) in the growing and regressing tail attended six to thirty fold increase respectively. However total activity in the trunk was decreased through progressive growing stages of metamorphosis. Total protein content in the trunk of tadpoles at climax stage (XXI) was decrease (35%) from 2.6mg/ml to 1.7mg/ml. The tail of tadpole tissue has shown a two fold increase in total Ribonucleic Acid (RNA) content from stage III to stage XVIII. But there was again decrease in total RNA content at climax stage (stage XXI). This might be possible due to decreased protein synthetic status. When the experiment was performed in trunk homogenate the amount of total carbohydrate (mg/ml) was slightly increased from 37mg/ml to 38.6mg/ml. this might be due to increase in the activity of α-amylase enzymes in the viscera of developing tadpole when it reached the climax stage.

Morphologically normal sperm have significantly greater total-RNA content than abnormal sperm

Introduction: Previous studies have demonstrated the presence of ribonucleic acid (RNA) in mature, ejaculated sperm and that sperm with poor motility have significantly more RNA than good motility sperm. However, no studies have investigated the relationship between RNA content and sperm morphology. Therefore, the study objective was to determine the relationship between total RNA content and sperm morphology. Methods: Sperm samples were separated by density centrifugation (Promotor, CERES Fertility, San Diego, CA) into morphologically normal and abnormal populations. Sperm morphology scores were determined by strict criteria. Total RNA was extracted from sperm via the Roche (Indianapolis, IN, USA) RNA isolation kit. Total RNA (μg of RNA per million sperm cells) recovered per sperm population from each ejaculate was determined by spectrophotometer and calculated as follows: (absorbance at 260 nm)×(conversion factor)×(dilution factor). The conversion factor for RNA is 0.04 μg/μl per optical density unit at 260 nm. Total RNA purity was calculated as the absorbance at 260 nm divided by the absorbance at 280 nm. Data were analyzed by Student's t-test. Results: A total of 179 semen specimens from different men underwent RNA extraction and analysis as described. All samples had absorbance readings between 0.1 and 1.0 at 260 nm and were determined to be accurate. Total RNA purity estimates for all samples were within the acceptable ratio of 1.7 and 1.9. RNA content in morphologically normal sperm (2.83±0.14 μg/10 6 cells) was significantly higher ( P<0.05) than the amount found in morphologically abnormal sperm (2.26±0.23 μg/10 6 cells). Conclusions: Ribonucleic acid content is significantly lower in morphologically abnormal sperm. Morphologically abnormal sperm may have impaired transcriptional and, or translational pathways thus negatively impacting cell function.

Presence of ribonucleic acid in human spermatozoa: Differences in content between normal and abnormal spermatozoa

Objective: Our purpose was to determine whether there are any differences in total ribonucleic acid content between normal and abnormal human spermatozoa. Study Design: Spermatozoa were obtained from men undergoing routine semen analysis at a university-based reproductive genetics laboratory. Specimens were classified as normal or abnormal according to World Health Organization criteria. Total ribonucleic acid was removed by acid-phenol extraction, and ribonucleic acid expression levels were determined by spectrophotometric analysis. Results: Abnormal spermatozoa were found to have significantly more ribonucleic acid (0.14 ± 0.02 mg/10 6 spermatozoa) than normal spermatozoa (0.05 ± 0.01 mg/10 6 spermatozoa; P < .001). Conclusion: Ribonucleic acid content is significantly altered in abnormal spermatozoa, and this alteration may be the result of some defect in the posttranscriptional pathway. (Am J Obstet Gynecol 2000;182:1011-2.)

Biologic activity and quantification of messenger RNA coding for human chorionic somatomammotropin in normal and intrauterine growth-retarded pregnancies

Total ribonucleic acid (RNA) from human placentas obtained from normal and intrauterine growth-retarded (IUGR) pregnancies was translated in a reticulocyte cell-free system. Synthesis of human chorionic somatomammotropin (hCS) was estimated as a ratio of specific immunoprecipitated protein over total newly synthesized proteins. There is no significant difference between in vitro hCS synthesis directed by placental RNA from normal and IUGR pregnancies. Measurements of messenger RNA sequences coding for hCS, with a hCS complementary DNA probe, indicated that the hCS messenger RNA (mRNA) concentrations were similar for both groups. Low plasma hCS levels in pregnancies associated with growth-retarded fetuses can be explained by their significantly lower placental weights which correlate with their total RNA content. The total capacity of in vitro hCS production per placenta is significantly lower in this type of abnormal pregnancy. There is a good parallelism between the amount of hCS mRNA, its biologic activity tested in a cell-free system, and the secretion of hCS in the maternal circulation. These data suggest that there is no basic intracellular disturbance in hCS synthesis in placentas from fetal growth-retarded pregnancies.

Physiological and biochemical studies on streptomycin dependence in Escherichia coli.

SUMMARY: The exponential growth rate of a streptomycin-dependent strain of Escherichia coli was proportional to streptomycin concentration until a critical concentration was reached, above which it was independent of streptomycin concentration. The value of the critical concentration changed with a change either in the carbon source, or in the temperature of cultivation. Below the critical concentration, the macromolecular composition of the cells was affected by the external streptomycin concentration: as this decreased, the ribonucleic acid (RNA) content of the organisms increased, and the protein content decreased. When external streptomycin was removed, streptomycin-dependent organisms continued to grow for many hours. Growth was at first exponential, the extent and duration of this phase being functions of the concentration of streptomycin to which the organisms had previously been exposed. This phase was followed by a much longer period of arithmetic growth, unaccompanied by cell division, during which the organisms elongated progressively. Growth in the absence of streptomycin caused changes in the macromolecular composition of the organisms which were similar in nature to those produced by growth with a subcritical concentration of streptomycin, but much more pronounced. The greatly increased total RNA content of these organisms was not accompanied by grossly detectable qualitative changes in the RNA content of the organisms. In the absence of streptomycin, the synthesis of some enzymes was either arrested or decreased in rate; the synthesis of others was unaffected. This leads to an imbalance in the enzymic constitution. These differential effects on enzyme synthesis appeared to be random. Growth in absence of streptomycin did not seem to affect deoxyribonucleic acid (DNA) synthesis or function, as shown by the ability of a lysogenic streptomycin-dependent strain to produce infective phage under such conditions. The re-introduction of streptomycin to a culture growing arithmetically as a consequence of streptomycin depletion caused a resumption of DNA synthesis at the normal exponential rate. The rate of protein synthesis also soon increased, but attained its normal exponential rate more slowly. RNA synthesis was wholly arrested until the RNA content of the organisms had fallen to a normal value, and then resumed at the normal exponential rate. Grown in the presence of a greater than critical concentration of streptomycin, the streptomycin-dependent organism bound irreversibly about 250,000 molecules of streptomycin, half of which could be extracted with hot water, and the remainder with hot perchloric acid. A new hypothesis concerning the location and nature of the genetically determined intracellular lesion which results in streptomycin dependence is developed on the basis of these facts.