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PubMed1990

The rIIA gene of bacteriophage T4. II. Regulation of its messenger RNA synthesis.

When the rII genes are first introduced into cells which had been previously infected by T4 phage deleted for these genes, the kinetics of synthesis of rIIA and rIIB RNA are rapid and identical. We show that this rapid synthesis depends on a functional motA gene for rIIB, but not for rIIA, RNA synthesis. By primer-extension mapping of T4 messenger RNA, we find three promoters close to the rIIA gene. One of them is an early promoter just before the rIIA.1 gene; it is used under all conditions tested. Another is in the coding portion of the rIIA.1 gene; it is weak, primarily because of a 19-bp spacing between the -10 and -35 elements, and its use is stimulated by T4 functions. The third is a motA-dependent (middle) promoter which has an unusual CCCGCTT box at -33. We present results which suggest that none of these promoters is likely to be the site at which the motB and motC gene products exercise their major influence on rIIA RNA synthesis.

Base Sequence↗

PubMed2001

Importance of the conserved nucleotides around the tRNA-like structure of Escherichia coli transfer-messenger RNA for protein tagging.

A bacterial RNA functioning as both tRNA and mRNA, transfer-messenger RNA (tmRNA) rescues stalled ribosomes and clears the cell of incomplete polypeptides. For function, Escherichia coli tmRNA requires an elaborate interplay between a tRNA-like structure and an internal mRNA domain that are connected by a 295 nt long compact secondary structure. The tRNA-like structure is surrounded by 16 unpaired nt, including 10 residues that are >95% conserved among the known 140 tmRNA sequences. All these residues were mutated to define their putative role(s) in trans-translation. Both the extent of aminoacylation and the alanine incorporation into the tag sequence, reflecting the two functions of tmRNA, were measured in vitro for all variants. As anticipated from the low sequence conservation, mutating positions 8-12 and position 15 affects neither aminoacylation nor protein tagging. Mutating a set of two conserved positions 13 and 14 abolishes both functions. Probing the solution conformation indicates that this defective mutant adopts an alternate conformation of its acceptor stem that is no more aminoacylatable, and thus inactive in protein tagging. Selected point mutations at the conserved nucleotide stretches 16-20 and 333-335 seriously impair protein tagging with only minor changes in their solution conformations and aminoacylation. Point mutations at conserved positions 19 and 334 abolish trans-translation and 70S ribosome binding, although retaining nearly normal aminoacylation capacities. Two proteins that are known to interact with tmRNA were purified, and their interactions with the defective RNA variants were examined in vitro. Based on phylogenetic and functional data, an additional structural motif consisting of a quartet composed of non-Watson-Crick base pairs 5'-YGAC-3':5'-GGAC-3' involving some of the conserved nucleotides next to the tRNA-like portion is proposed. Overall, the highly conserved nucleotides around the tRNA-like portion are maintained for both structural and functional requirements during evolution.

Acylation↗

PubMed1979

The synthesis and processing of a nuclear RNA precursor to rat pregrowth hormone messenger RNA.

A recombinant DNA plasmid, pBR322-GH1, which contains about 80% of the sequences of rat pregrowth hormone (pGH) mRNA, allowed an analysis of nuclear RNA from GH3 cells for possible precursors of cytoplasmic pGH mRNA. A single 20-22S RNA SPECIES ABOUT 2-3 TIMes larger than pGH mRNA was detected in nuclear RNA from GH3 cells labeled for 5 min. with 3H-uridine. After longer label times a 12S RNA indistinguishable in size from cytoplasmic 12S pGH mRNA became the predominant labeled RNA complementary to the plasmid pBR322-GH1. Both of these nuclear RNA species contained poly (A). Kinetic analysis of the labeling of nuclear and cytoplasmic pGH mRNA sequences showed that the 20S and 12S nuclear RNA molecules were labeled before significant labeling of cytoplasmic pGH mRNA was detected, and also indicated that there is complete conservation of nuclear pGH mRNA sequences in the production of cytoplasmic pGH mRNA. These results indicate that cytoplasmic pGH mRNA is generated by nuclear processing of a larger nuclear RNA molecule.

Animals↗

PubMed1965

Messenger RNA in early sea-urchin embryos: size classes.

Rapidly labeled RNA from four-cell embryos and blastulae of sea urchins was analyzed by sedimentation and for ability to form DNA-RNA hybrids. The RNA was derived from polyribosomes and from the "gel interphase," an extraction compartment resulting from treatment of whole embryos with phenol and known to be enriched with nuclei. The RNA from both sources displayed a high degree of structural complementarity to DNA. This DNA-like RNA of the polyribosomes sedimented in discrete classes, rather than in the sedimentation continuum demonstrable for the labeled RNA of the gel interphase. Thus messenger RNA appears to emerge in the cytoplasm in discrete size classes.

Animals↗

PubMed1992

Nucleotide sequence of messenger RNA encoding VHDJH and VKJK of a highly conserved idiotype-defined primary response anti-hapten antibody.

The primary humoral immune response of mice to the hapten phthalate (Xmp) is focused upon two adjacent immunodominant negatively charged carboxyl groups on a benzene ring that are in positions meta and para to the azolinkage (i.e., Xmp) to the protein carrier keyhole limpet hemocyanin. A significant fraction of the anti-Xmp antibodies raised in several different inbred mouse strains (BALB/c, DBA/2, A/HeHa; C3H, and SM/J), and many wild mouse populations express a cross-reactive Id, CRIXmp-1. This CRIXmp-1 is conspicuously absent in C57BL/6 mice. In order to obtain a better understanding of the events and parameters that influence the selection and regulation of the primary response B cell repertoire, and to explore the structural basis of Ag binding, we have determined the nucleotide sequence of the entire V region gene complexes, which encode the H and L chains of these highly conserved and dominant CRIXmp-1+ antibodies. Our data establish that the H chain gene complex consists of a single VH germ-line gene that is identical to VH Oxazolone-1, encoding the H chain of another highly conserved and dominant cross-reactive Id family associated with the primary response to Oxazolone. In CRIXmp-1+ Xmp-specific hybridomas this gene is joined to a limited set of D region sequences that express a conserved amino acid motif-GLR. At least three of the five D regions examined are coded for by DFL16.2. This VHD complex can be utilized with one of three different JH region genes (JH1, JH2, and JH4) without any significant effect upon antibody fine specificity or Id. In spite of this lack of JH fidelity all of the CRIXmp-1+ hybridomas have precisely maintained the same length in the H chain CDR3 and FRW4 by altering either the length of the D segment or the length of JH. Nucleotide sequence analysis of the VL gene complex of CRIXmp-1+ anti-Xmp antibodies indicates that the L chain V region is also encoded by a single germ-line gene. The amino acid sequence predicted from the nucleotide sequence of the VKJK from Xmp-specific CRIXmp-1+ hybridomas is identical to the sequence of the anti-arsonate antibody 1210.7, which is the prototype of another Id family (CRI) that is conserved and dominant in BALB/c mice.

Acute-Phase Reaction↗

PubMed1999

Expression of thymosin beta4 messenger RNA in normal and kainate-treated rat forebrain.

Thymosin beta4 is a major actin-sequestering peptide widely distributed in mammalian tissues, including the nervous system. In the present study, we analyse the expression of thymosin beta4 in normal and kainate-treated rat forebrain. In untreated animals, thymosin beta4 messenger RNA is mainly expressed in neurons of the hippocampal formation, neocortex and amygdaloid complex, as well as in oligodendrocytes. Other high-expressing areas are the tanycytic ependyma of the infundibulum, the substantia nigra pars compacta, and the supraoptic and premammillary nuclei. In rats treated with kainate, an excitotoxin that induces synaptic activation in the CA1-CA3 pyramidal neurons of the hippocampus, the levels of thymosin beta4 were clearly increased in the hippocampus and neocortex during the first 2-3 h after injection. In the long term, kainate causes neuronal degeneration in the CA1-CA3 regions of the hippocampus and functionally related structures, provoking a depletion of thymosin beta4 messenger RNA in these areas; however, the levels of this transcript are restored two weeks after kainate injection. Moreover, we have found that, in these degenerating zones, gliosis is accompanied by an elevation of the levels of thymosin beta4 messenger RNA, particularly in the CA1-CA3 region of the hippocampus, the lateral geniculate nucleus and the mammillothalamic tract. The present results demonstrate the existence of relatively high levels of thymosin beta4 messenger RNA in several areas of the rat forebrain, indicating that this peptide plays an important role in the regulation of actin polymerization in these regions of the brain. Moreover, the elevation of this messenger RNA after kainate treatment suggests a function of thymosin beta4 in the production and remodelling of neuronal processes. Finally, our findings provide evidence for a participation of this actin-sequestering molecule in the reactivity of certain types of glial cell that follows kainate lesions.

Animals↗

PubMed2006

Circulating cell-free fetal messenger RNA levels after fetoscopic interventions of complicated pregnancies.

OBJECTIVE: The aim of this study was to examine fetal gene expression in maternal plasma after fetoscopic intervention for twin-twin transfusion syndrome or congenital diaphragmatic hernia. STUDY DESIGN: Twelve women with pregnancies that were complicated by twin-twin transfusion syndrome and 10 women carrying fetuses with congenital diaphragmatic hernia were sampled before and sequentially after treatment. Levels of glyceraldehyde-3-phosphate dehydrogenase, human placental lactogen, and gamma globin messenger RNA were measured by real-time reverse transcriptase polymerase chain reaction amplification. RESULTS: At all time points, glyceraldehyde-3-phosphate dehydrogenase messenger RNA levels were higher in the congenital diaphragmatic hernia cases than in the twin-twin transfusion syndrome cases (P < .05), but during the immediate postoperative observation period, there were no significant changes in glyceraldehyde-3-phosphate dehydrogenase, human placental lactogen, or gamma globin messenger RNA levels in individual patients or patients who were grouped by procedure. CONCLUSION: Fetoscopic intervention of complicated pregnancies does not affect circulating fetal messenger RNA levels, which is in contrast to earlier observations that circulating fetal DNA levels increase after laser ablation for twin-twin transfusion syndrome. Plasma glyceraldehyde-3-phosphate dehydrogenase messenger RNA levels could be a potential novel biomarker for fetal trauma.

Female↗

PubMed2000

Requirement of transfer-messenger RNA for the growth of Bacillus subtilis under stresses.

BACKGROUND: Bacterial transfer-messenger RNA (tmRNA, 10Sa RNA) is involved in a trans-translation reaction which contributes to the degradation of incompletely synthesized peptides and to the recycling of stalled ribosomes. However, its physiological role in the cell remains elusive. In this study, an efficient system for controlling the expression of the gene for tmRNA (ssrA), as well as a tmRNA gene-defective strain (ssrA:cat), were constructed in Bacillus subtilis. The effects of tmRNA on the growth of the cells were investigated under various physiological culture conditions using these strains. RESULTS: The cells were viable in the absence of ssrA expression under the usual culture conditions. However, the growth rate of cells without tmRNA expression, relative to that of the expressed cells, decreased with elevating temperature (> 45 degrees C), and at 52 degrees C, the highest temperature for growth of the wild-type, cells grew depending on the expression level of tmRNA. Furthermore, the transcription level of the ssrA from the authentic promoter at a high temperature (51 degrees C) was about 10-fold higher than that at a lower temperature (37 degrees C). tmRNA-dependent growth and an increase in tmRNA amount were also observed in cells under other stresses, such as high concentrations of ethanol or cadmium chloride. It is also shown that alanylated tmRNA rather than tmRNA-mediated proteolysis is required for growth at high temperature. CONCLUSION: The expression of tmRNA gene (ssrA) is required for the efficient growth of B. subtilis under several strong stresses. The transcription of ssrA increases under several stressful conditions, suggesting that it is a stress-response gene. Alanyl-tmRNA, probably via its ability of recycling stalled ribosomes via trans-translation, is involved in the stress tolerance of bacteria.

Alanine↗

PubMed1984

Inhibition of nuclear envelope nucleoside triphosphatase-regulated nucleocytoplasmic messenger RNA translocation by 9-beta-D-arabinofuranosyladenine 5'-triphosphate in rodent cells.

Nucleocytoplasmic translocation of polyadenylated messenger RNA is an energy-dependent process which is regulated by a nuclear envelope nucleoside triphosphatase; this enzyme was found to be stimulated by the 3'-terminal polyadenylic acid [poly(A)] tail of messenger RNA (Bernd, A., Schröder, H. C., Zahn, R. K., and Müller, W. E. G. Eur. J. Biochem., 129: 43-49, 1982). RNA efflux from isolated mouse lymphoma (L5178Y) cell nuclei is strongly reduced if 9-beta-D-arabinofuranosyladenine 5'-triphosphate (ara-ATP) is present in the transport medium. Half-maximal inhibition of RNA efflux occurs with 120 microM ara-ATP. Most likely, the inhibitory effect of ara-ATP is caused by inhibition of nuclear envelope nucleoside triphosphatase; this enzyme was found to be highly sensitive to inhibition by this antibiotic. The inhibition type of the nucleoside triphosphatase of rat liver nuclear ghosts is competitive with respect to ATP; the Ki:Km ratio was determined to be 0.27. Besides nucleoside triphosphatase, nuclear envelopes contain a protein phosphokinase modulating the affinity of pore complex laminae to poly(A). This enzyme was also found to be strongly inhibited by ara-ATP in a competitive way with respect to ATP (Ki:Km, 0.056) and could therefore also contribute to the overall inhibition of RNA transport. The polyadenylation of endogenous RNA by poly(A) polymerase(s) in intact rat liver nuclei as well as in nuclear matrices isolated from the same source was found to be markedly suppressed in the presence of ara-ATP. The inhibitions of both poly(A) polymerase activities (contained in whole nuclei or nuclear matrix bound) are of the competitive type with respect to ATP. In in vitro assays, nuclear envelope nucleoside triphosphatase is inhibited by microtubule protein. Of the 2 ATP-dependent enzyme activities associated with microtubule protein (cyclic adenosine 3':5'-monophosphate-dependent protein kinase and adenosine triphosphatase), only the kinase was slightly affected by ara-ATP. Cellular uptake of adenosine 5'-monophosphate and perhaps 9-beta-D-arabinofuranosyladenine 5'-monophosphate (ara-AMP) is facilitated by a cellular membrane-bound 5'-nucleotidase. Our studies revealed that neither cleavage of ara-AMP nor inhibition of the enzyme activity by ara-AMP occurs. 9-beta-D-Arabinofuranosyladenine and ara-AMP represent neither direct mutagens nor premutagens as determined by the Salmonella-mammalian microsome mutagenicity test.

Animals↗

PubMed1998

The messenger RNA encoding VGF, a neuronal peptide precursor, is rapidly regulated in the rat central nervous system by neuronal activity, seizure and lesion.

The VGF gene encodes a neuronal secretory-peptide precursor that is rapidly induced by neurotrophic growth factors and by depolarization in vitro. VGF expression in the animal peaks during critical periods in the developing peripheral and central nervous systems. To gain insight into the possible functions and regulation of VGF in vivo, we have used in situ hybridization to examine the regulation of VGF messenger RNA by experimental manipulations, and have found it to be regulated in the CNS by paradigms that affect electrical activity and by lesion. Inhibition of retinal electrical activity during the critical period of visual development rapidly repressed VGF messenger RNA in the dorsal lateral geniculate nucleus of the thalamus. In the adult, kainate-induced seizures transiently induced VGF messenger RNA in neurons of the dentate gyrus, hippocampus, and cerebral cortex within hours. Cortical lesion strongly induced VGF messenger RNA in ipsilateral cortex within hours, and strongly repressed expression in ipsilateral striatum. Ten days postlesion there was a delayed induction of VGF messenger RNA in a portion of deafferented striatum where compensatory cortical sprouting has been detected. Expression of the neuronal secretory-peptide precursor VGF is therefore modulated in vivo by monocular deprivation, seizure, and cortical lesion, paradigms which lead to neurotrophin induction, synaptic remodeling and axonal sprouting.

Animals↗

PubMed1994

Vasoactive intestinal polypeptide/peptide histidine isoleucine messenger RNA in the rat retina: adult distribution and developmental expression.

In the adult nervous system, vasoactive intestinal polypeptide acts as a neurotransmitter or neuromodulator, and during development, it may also act as a neurotrophic factor. In the adult mammalian retina, this peptide is contained in a population of wide-field amacrine cells. Using in situ hybridization histochemistry, we examined the distribution and developmental expression of vasoactive intestinal polypeptide/peptide histidine isoleucine messenger RNA in the rat retina. Retinas collected from birth to adulthood were hybridized with an RNA probe as whole mounts, and then cut either perpendicular or parallel to the vitreal surface. Adult retinas were used in double labeling experiments for the visualization of both the hybridization signal and vasoactive intestinal polypeptide immunoreactivity in the same tissue section. In adult retinas, vasoactive intestinal polypeptide/peptide histidine isoleucine messenger RNA is localized to amacrine cells positioned in the proximal inner nuclear layer, and rarely to displaced amacrine cells in the inner plexiform layer and ganglion cell layer. The neurons expressing this messenger RNA are sparsely distributed, with a non-random distribution and densities of about 190 cells/mm2. An estimate of their total number gives about 12,350 cells/retina. The double labeling experiments showed that the hybridization signal is specifically confined to neurons displaying vasoactive intestinal polypeptide immunoreactivity. Vasoactive intestinal polypeptide/peptide histidine isoleucine messenger RNA is first detected at postnatal day 5 in cells located in the proximal part of the neuroblastic layer. A greater number of these neurons is present in the inner nuclear layer at postnatal day 10, and a few labeled neurons are also detected in the inner plexiform layer and in the ganglion cell layer. At this time, vasoactive intestinal polypeptide/peptide histidine isoleucine messenger RNA-containing amacrines in the inner nuclear layer are non-randomly distributed on the retinal surface, as in adult retinas. At postnatal day 15 (eye opening), there is a peak in both the density and the estimated number of labeled neurons, and their pattern of distribution in the retinal layers is similar to that in the adult. The present study shows that in the adult rat retina vasoactive intestinal polypeptide and peptide histidine isoleucine are synthesized in a sparsely distributed amacrine cell population, extending previous immunohistochemical findings. The appearance of vasoactive intestinal polypeptide peptide histidine isoleucine messenger RNA during the first postnatal week is consistent with the reported appearance of other transmitter-identified amacrine cell populations.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1995

Retrograde transport of nerve growth factor from hippocampus and amygdala to trkA messenger RNA expressing neurons in paraventricular and reuniens nuclei of the thalamus.

We previously reported the presence of trkA messenger RNA expressing non-cholinergic neurons in the paraventricular anterior and reuniens nuclei, which are located in the thalamic midline. In the present study, retrograde labeling with iodinated (125I) nerve growth factor was used to identify the innervation target of these cells. Neurons in the paraventricular anterior and reuniens nuclei were labeled following injection of iodinated nerve growth factor into amygdala and hippocampus, but not into nucleus accumbens and entorhinal cortex, the two other main areas receiving strong innervation from the thalamic midline. Target ablation of hippocampus or amygdala failed to down-regulate trkA messenger RNA expression in the two thalamic nuclei, thus suggesting a role for nerve growth factor different from a critical survival factor. The thalamic paraventricular anterior and reuniens nuclei are part of the reticular formation which plays a role in general cortical activation, behavioral arousal and control of awareness. Retrograde transport of nerve growth factor by trkA messenger RNA expressing neurons in these nuclei suggests a physiological role of this trophic factor in the function of these cells.

Amygdala↗

PubMed1985

Isolation and partial characterization of the messenger RNA encoding the B880 holochrome protein of Rhodospirillum rubrum.

The B880 holochrome messenger RNA was extracted from cultures of the photosynthetic bacterium Rhodospirillum rubrum. It was purified by chromatography on Sepharose 4B followed by sucrose density gradient centrifugation. The purified fractions were shown to program an Escherichia coli cell-free system into synthesizing both the alpha and the beta polypeptides of the holochrome. The translation products were identified by immunoprecipitation with specific antibodies raised against these polypeptides. The latter are effective competitors with the translation products for antigen-antibody complex formation. The purest mRNA preparations contained approximately 33% holochrome messenger RNA activity. Its most probable size, as determined by agarose gel electrophoresis in the presence of 6 M urea or methylmercuric hydroxide, is approximately 620 nucleotides. Since the combined sizes of the alpha and beta polypeptides add up to only 106 amino acid residues, we conclude that the holochrome mRNA is most probably polycistronic.

Bacterial Proteins↗

PubMed1978

Effects of steroid hormones on the level of corticotropin messenger RNA activity in cultured mouse-pituitary-tumor cells.

Studies have been made with the mouse pituitary tumor cell line AtT-20 in culture to determine whether or not the suppression of pituitary corticotropin messenger RNA activity observed upon the administration of glucocorticoids to adrenalectomized rats is due to a direct action of these steroid hormones on the pituitary. The levels of corticotropin messenger RNA activity in AtT-20 cells treated with various steroid hormones were measured with the use of the cell-free protein-synthesizing system derived from wheat germ. The addition of dexamethasone to culture medium reduced the level of corticotropin messenger RNA activity to 30-40% of that in untreated cells. Corticosterone and cortisol exhibited a suppressive effect to a lesser extent. In contrast, nonglucocorticoids such as testosterone and 17beta-estradiol were essentially ineffective. These results indicate that at least part of the glucocorticoid action is exerted directly on the pituitary to suppress corticotropin messenger RNA activity.

Adrenocorticotropic Hormone↗

PubMed1999

Psychophysiological stress induces heat shock cognate protein 70 messenger RNA in the hippocampus of rats.

Psychophysiological stress has been shown to increase 70,000 mol. wt heat shock protein messenger RNAs with northern blotting in rats. However, its localization is unknown. With in situ hybridization, we tested our hypothesis that restraint water-immersion stress may induce heat shock cognate protein 70 messenger RNA expression simultaneously with some morphological changes selectively in the hippocampus of rats. Stress for 6 h significantly increased heat shock cognate protein 70 messenger RNAs in the hippocampus, with maximal intensity in the CA3 subfield of the Ammon's horn and to a lesser extent in CA2. Stress for 12 h significantly increased heat shock cognate protein 70 messenger RNAs in the whole hemisphere including the cerebral cortex, the thalamus, the hypothalamus, and the hippocampus with the highest density in CA3. Heat shock cognate protein 70 messenger RNA in rats with stress for 6 h followed by recovery for 6 h significantly increased at CA3 and CA2 compared with the controls or rats stressed for 6 h without recovery. No overt histological changes were detected in neuronal or glial cells in the slides of hematoxylin-eosin or Cresyl Violet staining. These results show that psychophysiological stress induces heat shock cognate protein 70 messenger RNA in the most stress-vulnerable brain structure, hippocampal CA3, probably for cytoprotection.

Animals↗

PubMed1992

Relative abundance of human placental phospholipase A2 messenger RNA in late pregnancy.

The aim of this study was to determine messenger RNA (mRNA) levels for a specific phospholipase A2 (PLA2) in human placenta during late gestation prior to the onset of labour. The relative abundance of human placental mRNA for a nonpancreatic Group II PLA2 was determined using cDNA clone specific for this PLA2. Twenty seven placentae were collected from women undergoing elective (i.e. before the onset of labour) Caesarean section between 37 and 41 completed weeks gestation. The relative amount of human placental PLA2 mRNA did not change significantly over this period of late pregnancy (p greater than 0.8). Previously, we have demonstrated that placental PLA2 messenger RNA levels are increased in association with spontaneous onset labour at term in the human. The data obtained in this current study are consistent with the conclusion that the regulation of this human placental PLA2 gene is tightly controlled around the time of parturition and that its expression is increased acutely in association with labour.

Blotting, Northern↗

PubMed1991

Messenger RNA splicing in yeast: clues to why the spliceosome is a ribonucleoprotein.

The removal of introns from eukaryotic messenger RNA precursors shares mechanistic characteristics with the self-splicing of certain introns, prompting speculation that the catalytic reactions of nuclear pre-messenger RNA splicing are fundamentally RNA-based. The participation of five small nuclear RNAs (snRNAs) in splicing is now well documented. Genetic analysis in yeast has revealed the requirement, in addition, for several dozen proteins. Some of these are tightly bound to snRNAs to form small nuclear ribonucleoproteins (snRNPs); such proteins may promote interactions between snRNAs or between an snRNA and the intron. Other, non-snRNP proteins appear to associate transiently with the spliceosome. Some of these factors, which include RNA-dependent adenosine triphosphatases, may promote the accurate recognition of introns.

Adenosine Triphosphate↗

PubMed1965

Comparison of messenger RNA in photoperiodically induced and noninduced Xanthium buds.

In response to the floral stimulus, Xanthium buds synthesize relatively more messenger RNA than do vegetative buds. This is demonstrated by fractionation, on methylated albumin-kieselguhr columns, of a mixture of nucleic acids from vegetative and induced buds, one being labeled with uridine-H(3) and the other with uridine-2-C(14). While floral induction stimulates a small increase in messenger RNA synthesis as revealed by labeling intact plants, this difference can be magnified by labeling excised buds in solution. From experiments with excised buds from Xanthium plants, it is concluded that buds from photoperiodically induced plants contain more messenger RNA than buds from noninduced ones do.

Carbon Isotopes↗