Regulation of Ribosomal RNA and 5s RNA Synthesis in DROSOPHILA MELANOGASTER: I. Bobbed Mutants

Analysis of the rates and amounts of rRNA and 5s RNA synthesized in Drosophila melanogaster bobbed mutants was done by using acrylamide-gel electrophoresis. The results show that the amounts of rRNA synthesized are constant, although the rates of rRNA synthesis in bb's are reduced to 30% of the wild-type level. The rates of synthesis of 5s RNA were constant. The rate of synthesis of the two kinds of molecules that enter in equimolar amounts into the mature ribosome is non-coordinated.-The rates of rRNA synthesis were shown to be proportional to the length of the scutellar bristles, supporting the notion that in trichogen cells there is no developmental delay, but the size of the bristle depends directly on the rate of rRNA synthesis.     

The effect of short-term fasting and a single meal on protein synthesis and oxygen consumption in cod,Gadus morhua

Summary Rates of protein synthesis and oxygen consumption ( O₂) in cod were compared in both fasted and refed animals. During a 14-day fast both protein synthesis and respiration rates fell to stable values after 6 days. When a meal of whole sandeel at 6% body weight was fed to fish fasted for 6 days, protein synthesis and ( O₂) increased to a maximum at between 12 and 18 h after feeding. Peak ( O₂) was about twice the pre-feeding values, while whole animal protein synthesis increased four-fold. There were differences between tissues in the timing of maximum protein synthesis; the liver and stomach responded faster than the remainder of the body. Maximum protein synthesis rates in the liver and stomach occurred at 6 h after feeding, at which time their calculated contribution to total ( O₂) was 11%. Similar calculations suggested that the integrated increment in whole animal protein synthesis contributed between 23% and 44% of the post-prandial increase in ( O₂). It was concluded that protein synthesis is an important contributor to increased ( O₂) after feeding in cod.Abbreviations A _s absolute rate of protein synthesis - ASDA apparent specific dynamic action - ATP adenosine triphosphate - k _s fractional rate of protein synthesis - k _s/RNA amount of protein synthesized per unit RNA - ( O₂) oxygen consumption - PCA perchloric acid - RNA ribonucleic acid     

26S and 18S rRNA synthesis in bobbed mutants of Drosophila melanogaster

For the most part, bobbed mutations of Drosophila melanogaster consist of deletions of 26S and 18S rDNA located on the X and Y chromosomes. Studies on the synthesis of rRNA of third instar larvae and one day old adult females of three severe bobbed genotypes, indicate that no decrease can be detected, compared ot wild type strains. One of the bobbed mutants studied was a rather unusual type: these flies possess a quantity of rDNA that should confer upon them a near wild type phenotype whereas they actually show an extreme bobbed phenotype. The two other bobbed mutants are of a classical type: their severe bobbed phenotype corresponds to large deletions of rDNA. Two hypotheses can be proposed to explain the extreme bobbed phenotype of the flies, in spite of the fact that rRNA synthesis occurs normally. A regulatory phenomenon may interfere at the stages studied, but in earlier stages a net decrease in rRNA synthesis may have occurred producing an irreversible effect in the tissues affected by bobbed mutations (abdominal cuticle, bristles). The second hypothesis is that the rRNA produced may not be functional, perhaps because it is specific of earlier stages.     

RNA transcription and translation in sea urchin oocytes and eggs

The steady-state concentrations and absolute rates of synthesis of ribosomal RNA (rRNA) molecules were measured in oocytes, eggs, embryos, and larvae of the Hawaiian sea urchin Tripneustes gratilla. The steady-state concentration per genome of the RNA precursor sequences measured by hybridization to a cloned rDNA fragment was approximately 100- to 300-fold greater in the RNA obtained from oocytes and eggs than in the RNA extracted from embryos and larvae. Since the rate of processing of the rRNA precursor at different stages is not greatly different, the rates of rRNA synthesis must be considerably greater in oocytes than in embryo cells. The absolute rate of RNA synthesis in oocytes and embryos was determined from the incorporation of [³H]guanosine into cellular GTP pools and into both precursor and mature rRNA species. The data indicate an approximately 40-fold higher rate of rRNA synthesis in oocytes than that measured in embryos or previously in larvae (J. Griffith and T. Humphreys, 1979, Biochemistry18, 2178–2185). Together these results indicate that the ribosomal genes are transcribed much more rapidly during sea urchin oogenesis than during embryogenesis or larval stages.     

Inter- and intra-population differences in the effects of temperature on postdiapause development of Delia radicum

Canadian populations of D. radicum differ in their response to temperature during postdiapause development. Populations that are primarily of the early-emerging type ( ) (St-Jean, Quebec; London, Ontario) have high values for the parameters describing this response: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOuamaaBa% aaleaacaWGTbaabeaakiabg2da9aaa!38F2!$$R_m = $$ 12.7–13.3; 28.0–31.8 °C ; T = 10.3–14.2 ( , the maximum developmental rate at the temperature, [ °C ] where the developmental rate is highest, and T , the parameter which gives the shape of the truncated normal curve fitted to the data), a low degree-day requirement for emergence (160–232 ), and may lack a developmental delay at temperatures above ca. 21 °C . Populations of the late-emerging type (Kildare, Prince Edward Island) have low parameter values ( , °C ; T = 6.4), high degree-day requirements (530 ), and a developmental delay at high temperatures. The parameters for the early-emergers in the population from Winnipeg, Manitoba (74% early) were intermediate ( , °C , T = 10.7, ), but resembled the early rather than the late type. This population varied from 31 to 90% early type over a 10-year period and the rate of postdiapause development at 20 °C was directly related to the percentage early. In the year with the most rapid development (90% early), development was significantly slower than in the populations from other locations with predominantly early populations, and the year with the slowest development (31% early) showed significantly faster development than that from Kildare, Prince Edward Island (100% late). Therefore the parameters for early and late types of development will not be accurate for use in mixed populations, and the parameters in mixed populations will change among years. Populations of D. radicum in North America and Europe (67 locations by years) varied from 0–100% early. At Winnipeg, the percentage early was directly related to the annual temperature accumulation ( ) during the growing season. The calculation of developmental parameters for the early-emergers of mixed populations provides a more accurate basis for estimating the times of first emergence and the first peak of emergence than parameters based on the whole population. Since postdiapause developmental rates vary both among and annually within locations, developmental models should be designed to include such variations.     

Impact of P-Site tRNA and Antibiotics on Ribosome Mediated Protein Folding: Studies Using the Escherichia coli Ribosome

Background

The ribosome, which acts as a platform for mRNA encoded polypeptide synthesis, is also capable of assisting in folding of polypeptide chains. The peptidyl transferase center (PTC) that catalyzes peptide bond formation resides in the domain V of the 23S rRNA of the bacterial ribosome. Proper positioning of the 3′ –CCA ends of the A- and P-site tRNAs via specific interactions with the nucleotides of the PTC are crucial for peptidyl transferase activity. This RNA domain is also the center for ribosomal chaperoning activity. The unfolded polypeptide chains interact with the specific nucleotides of the PTC and are released in a folding competent form. In vitro transcribed RNA corresponding to this domain (bDV RNA) also displays chaperoning activity.

Results

The present study explores the effects of tRNAs, antibiotics that are A- and P-site PTC substrate analogs (puromycin and blasticidin) and macrolide antibiotics (erythromycin and josamycin) on the chaperoning ability of the E. coli ribosome and bDV RNA. Our studies using mRNA programmed ribosomes show that a tRNA positioned at the P-site effectively inhibits the ribosome''s chaperoning function. We also show that the antibiotic blasticidin (that mimics the interaction between 3′–CCA end of P/P-site tRNA with the PTC) is more effective in inhibiting ribosome and bDV RNA chaperoning ability than either puromycin or the macrolide antibiotics. Mutational studies of the bDV RNA could identify the nucleotides U2585 and G2252 (both of which interact with P-site tRNA) to be important for its chaperoning ability.

Conclusion

Both protein synthesis and their proper folding are crucial for maintenance of a functional cellular proteome. The PTC of the ribosome is attributed with both these abilities. The silencing of the chaperoning ability of the ribosome in the presence of P-site bound tRNA might be a way to segregate these two important functions.     

Influence of hyperbaric oxygen tension on the metabolism of Candida tropicalis and Rhodococcus erythropolis

Summary The effect on metabolism of hyperbaric dissolved oxygen tension in batch cultures of Candida tropicalis (Cast.) Berkhout and Rhodococcus erythropolis with three different carbon sources was studied in a 20-l bioreactor under controlled conditions. The respiratory quotient was not significantly influenced by dissolved oxygen concentrations up to 40 mg/l oxygen. Elementary cell composition and proportional contents of DNA, RNA, and protein were not markedly influenced by the various oxygen concentrations but depended mainly on the growth rate. It was found that the production of trehalose lipid by R. erythropolis was dependent on the growth rate which could be enhanced by raising the oxygen concentration. The specific activity of catalase was affected more by the nature of the carbon source than by increased oxygen concentration. On the basis of the experimental data the application of oxygen-enriched air for biotechnological processes is discussed.Symbols and abbreviations k_La Specific volumetric oxygen transfer rate - Oxygen consumption rate, grams oxygen per hour and per liter - Carbon dioxide production rate, grams carbon dioxide per hour and per liter - RQ Respiratory quotient, - t Cultivation time - Y_X/S Yield coefficient, grams cell dry weight/grams substrate - Yield coefficient, grams cell dry weight/grams oxygen consumed - Y_kJ Yield coefficient, grams cell dry weight/heat of combustion of the consumed substrate - Y_ave– Yield coefficient, grams cell dry weight/mol available electrons of the consumed substrate     

Optimization of the synthesis of porcine somatotropin in Escherichia coli

We report on the influence of choice of promoter and RNA polymerase, 5-untranslated regions and ribosome binding sites, codon usage, leader peptide coding sequences and poly A tail in the 3-untranslated region on the synthesis of porcine somatotropin (PST) in Escherichia coli. A total of 12 different constructs were tested in this study for the production of porcine somatotropin (PST) in E. coli. Several factors have significant effects on PST synthesis. In the presence of a strong promoter and a strong ribosome binding site, the next most important factor seems to be the combination of sequences at the 5-end of the mRNA including both the 5-untranslated region and the start of the coding sequence. Codon usage in the 5-coding sequence per se is not important in determining the level of PST synthesis where high level expression is achieved from a strong ribosome binding site. However, where low level synthesis of recombinant PST (rPST) is achieved, codon usage in the 5-coding sequence is important in determining the level of PST synthesis. Leader sequences dramatically reduce the level of PST synthesis. The presence of a poly A tail in the 3-untranslated region has no significant effect on PST synthesis.     

Differential replication of ribosomal DNA during larval development in Calliphora (Diptera)

The hybridization of ribosomal RNA with DNA extracted from whole insects has been compared at six stages during the development of the blowfly Calliphora stygia. Total DNA from hatching larvae contains approximately 20% more rDNA than does total DNA from either mid-embryonic or adult insects. DNA from late third-instar larvae close to pupariation contains about 30% less rDNA than that from hatching larvae. The proportion of rDNA to total DNA in larvae of intermediate ages falls between these two extremes. Ribosomal RNA cistrons are thus replicated more rapidly than the remainder of the genome in the late embryonic or earliest larval stages, but more slowly during the later cycles of DNA synthesis in those larval tissues which develop high levels of polyteny.     

Comparing plant life histories using elasticity analysis: the importance of life span and the number of life-cycle stages

Recent studies have used transition matrix elasticity analysis to investigate the relative role of survival (L), growth (G) and fecundity (F) in determining the estimated rate of population increase for perennial plants. The relative importance of these three variables has then been used as a framework for comparing patterns of plant life history in a triangular parameter space. Here we analyse the ways in which the number of life-cycle stages chosen to describe a species (transition matrix dimensionality) might influence the interpretation of such comparisons. Because transition matrix elements describing survival (stasis) and growth are not independent, the number of stages used to describe a species influences their relative contribution to the population growth rate. Reduction in the number of stages increases the apparent importance of stasis relative to growth, since each becomes broader and fewer individuals make the transition to the next stage per unit time period. Analysis of a test matrix for a hypothetical tree species divided into 4–32 life-cycle stages confirms this. If the number of stages were defined in relation to species longevity so that mean residence time in each stage were approximately constant, then the elasticity of G would reflect the importance of relative growth rate to . An alternative, and simpler, approach to ensure comparability of results between species may be to use the same number of stages regardless of species longevity. Published studies for both herbaceous and woody species have tended to use relatively few stages to describe life cycles (herbs: n=45, ; woody plants: n=21, ) and so approximate this approach. By using the same number of stages regardless of longevities, the position of species along the G-L side of the triangular parameter space largely reflects differences in longevity. The extent of variation in elasticity for L, G and F within and between species may also be related to factors such as successional status and habitat. For example, the shade-tolerant woody species, Araucaria cunninghamii, shows greater importance for stasis (L), while the gap-phase congener species, Araucaria hunsteinii, shows higher values for G (although values are likely to vary with the stage of stand development).     

Edeine inhibition and resistance in Neurospora

To obtain data on the biochemical effects of edeine in the fungus Neurospora crassa, in vivo protein synthesis, in vitro protein synthesis, as well as in vivo RNA and DNA synthesis of the wildtype and an edeine resistant mutant were measured.—Incorporation of ³H leucine into conidia of both strains, which served as a measure for in vivo protein synthesis, was inhibited by 200 g edeine/ml as follows: Wildtype approx. 40%, mutant approx. 6%.—Incorporation of ¹⁴C phenylalanine into polyphenylalanine in a cell free system with ribosomes from either the wildtype or the mutant, was inhibited between 74 and 95% by edeine at a ratio of 2 molecules edeine per ribosome.—Incorporation of ³H adenosine into conidia, serving as a measure for in vivo RNA synthesis, was inhibited in the wild-type (approx. 30% inhibition by 200 g edeine/ml). It was, however, not influenced in the ed ^r mutant. Similarly, in vivo DNA synthesis was decreased in the wildtype, but not in the mutant.—These results suggest that edeine acts at more than one site. The resistance of the mutant ed ^r -29 (ed ^r -2 locus) is tentatively interpreted as due to a block in edeine uptake.     

Decay and synthesis of ribosomal proteins during Dictyostelium discoideum development

Summary Ribosome turnover is a prominent process during cell differentiation in Dictyostelium discoideum. At the end of 24 h of development on filters, the cells contain only 30% of the ribosome content of vegetatively growing cells. We determined the relative rates of synthesis and decay of each of the ribosomal proteins during this period. Approximately 80% of the total vegetative cell ribosomal proteins were degraded during the course of fruiting body construction. Ribosomal RNA and protein degradation apparently occurred coordinately during development. Although all ribosomal proteins decayed during development, some were more stable and a few less stable than the average. In addition, all the ribosomal proteins were synthesized during this period. Most ribosomal proteins were synthesized at the same rate as other cellular proteins, although a number were made at lower or higher rates. It was estimated that about 35% of the ribosomes in developed cells represented those, that were made during cell differentiation. Differential decay and/or synthesis of ribosomal proteins could account for the observed difference in protein content of ribosomes from growing amoebae and late development cells and spores.Paper No. 4 in the series, Studies on Ribosomal Proteins in Dictyostelium discoideum. Paper No. 3 is Ramagopal and Ennis (1982)     

Genome‐wide characterization and developmental expression profiling of long non‐coding RNAs in Sogatella furcifera

The genome‐wide characterization of long non‐coding RNA (lncRNA) in insects demonstrates their importance in fundamental biological processes. Essentially, an in‐depth understanding of the functional repertoire of lncRNA in insects is pivotal to insect resources utilization and sustainable pest control. Using a custom bioinformatics pipeline, we identified 1861 lncRNAs encoded by 1852 loci in the Sogatella furcifera genome. We profiled lncRNA expression in different developmental stages and observed that the expression of lncRNAs is more highly temporally restricted compared to protein‐coding genes. More up‐regulated Sogatella furcifera lncRNA expressed in the embryo, 4th and 5th instars, suggesting that increased lncRNA levels may play a role in these developmental stages. We compared the relationship between the expression of Sogatella furcifera lncRNA and its nearest protein gene and found that lncRNAs were more correlated to their downstream coding neighbors on the opposite strand. Our genome‐wide profiling of lncRNAs in Sogatella furcifera identifies exciting candidates for characterization of lncRNAs, and also provides information on lncRNA regulation during insect development.     

Effect of anthropometric characteristics and socio-economic status on physical performances of pre-pubertal children living in Bolivia at low altitude

We have previously observed that 11-year-old children of low socio-economic status (LSES) showed a delayed physical growth of approximately 2 years and developed lower normalized short-term power output than children of high socio-economic status (HSES) of the same age. In contrast, maximal oxygen uptake per unit of fat free mass was no different in either group. The aim of this study was to evaluate the effect of anthropometric characteristics between HSES and LSES prepubertal children in aerobic and anaerobic performance. To compare children of the same body dimensions, 11-year-old boys (n = 30) and girls (n = 31) of LSES and 9-year-old boys (n = 21) and girls (n = 27) of HSES were studied. Anthropometric measurements, (direct test), maximal anaerobic power (P _max, force-velocity test) and mean anaerobic power ( , Wingate test) were determined. In these children having the same body dimensions: mean were the same in LSES and HSES children [1.2 (SD 0.2)1-min^–1];P _max and were lower in LSES subjects [154.0 (SD 33.2) vs 174.6 (SD 38.4) W and 116.3 (SD 23.3) vs 128.2 (SD 28.0) W, respectively]; the linear relationships between and fat free mass were the same in LSES and HSES boys but, in the girls, the LSES group had lower values. For anaerobic performance, the relationships were significantly different: the slopes were the same but LSES values for the both sexes were lower. These results would suggest that factors other than differences in body dimensions alone were responsible for the lower performance of LSES girls and boys. Cultural factors and motor learning, structural and functional alterations of muscle induced by marginal malnutrition have been discussed.     

The ribosome cycle,nucleoli, and cytoplasmic nucleoloids in the meiocytes ofLilium

Summary During the meiotic prophase in pollen mother cells ofLilium species the ribosome population of the cytoplasm diminishes to a minimum reached during the diplotene-diakinesis interval. This fall is associated with a drop in the ribonuclease-extractable RNA present in whole, fixed cells. A rise in RNA and in number of observable ribosomes follows during the meiotic mitoses and in the very early life of the spores. Bodies with the characteristics of nucleoli—here termed nucleoloids—are released into the cytoplasm at anaphase I and anaphase II, and it is suggested that these may represent the main mechanism through which the ribosome population of the cytoplasm is restored after the prophase elimination.     

The effect of a rosette-crown fly, Botanophila turcica, on growth,biomass allocation and reproduction of the thistle Carthamus lanatus

Plant growth and reproductive output of the winter annual invasive thistle, Carthamus lanatus was characterised in relation to plant size in three native populations in southern France. The effects of the rosette-crown feeding fly Botanophila turcica on these plant characteristics were assessed by comparing unattacked with naturally attacked plants at each site and by a field experiment. Indirect effects of B. turcica on plant seed production were also compared with direct seed loss caused by a guild of capitulum-feeding insects that incidentally attacked the marked plants at these sites. C. lanatus showed no size or weight requirement for flowering, but larger flowering plants produced less total receptacle surface and less seed production (female reproductive potential) in proportion to plant weight than smaller flowering plants. B. turcica did not select hosts on the basis of size or density. B. turcica reduced plant relative growth rate (RGR) in all situations, but attacked plants compensated fully at two of three sites as attack failed to halt rosette growth. Attacked plants suffered 12 % mortality, and 71 % lower seed production than unattacked plants at the site with the lowest RGR. This corresponded to 9 % lower seed production for the whole thistle population compared to 8.6–19.5 % direct seed loss to capitulum insects across all sites.