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PubMed1993

Localization of interleukin-1 type I receptor and interleukin-1 beta in human endometrium throughout the menstrual cycle.

Previous studies in the human suggest that the interleukin-1 (IL-1) system, may be an important paracrine/autocrine mediator in local intercellular interaction in endometrial tissue. In this study we have determined that IL-1 receptor type I (IL-1R tI) is expressed at the messenger RNA (mRNA) and protein levels in glandular cells and its ligand, IL-1 beta has been localized by immunohistochemical methods in endothelial cells and isolated stromal cells in the human endometrium throughout the menstrual cycle. IL-1R tI mRNA was detected in glandular epithelium using both specific complementary DNA and complementary RNA 32P-labeled probes. Human glandular epithelium contains a 5.1-kilobase mRNA transcript throughout the complete menstrual cycle. Quantitative densitometric analysis of slot blot hybridization signals shows an increase of IL-1R tI mRNA in both early and mid-late secretory phases in comparison with the proliferative phase (P < 0.05). IL-1R tI protein was localized in endometrial glandular epithelial cells using both indirect immunofluorescence and avidin-biotin-peroxidase methods. However, more intense staining for IL-1R tI was observed in lumenal epithelial cells compared with the staining present deep in the endometrial glands. Using the same methods, IL-1 beta was detected in endothelial cells of spiral vessels and isolated stromal cells throughout the menstrual cycle, and an increased staining from proliferative to secretory phase was observed. The detection of IL-1R tI in the human endometrial epithelium and its ligand, IL-1 beta, in isolated stromal cells and endothelial cells, is another example of possible communication between the immune and reproductive systems with special relevance to human implantation.

Adult↗
PubMed1993

Localization of janusin mRNA in the central nervous system of the developing and adult mouse.

Janusin (formerly termed J1-160/180) is an oligodendrocyte-derived extracellular matrix molecule which is restricted to the central nervous system and which is expressed late during development (Pesheva et al., J. Cell Biol., 1765-1778, 1989). To gain insights into the molecule's morphogenetic functions and to identify its cellular source in vivo, we have studied the localization of janusin messenger RNA in the optic nerve, retina and spinal cord and the expression of janusin protein in the spinal cord of developing and adult mice. Moreover, we have analysed optic nerve cell cultures and retinal cell suspensions in double-labelling experiments using a janusin-specific anti-sense complementary RNA probe and cell type-specific antibodies to identify the cell types containing janusin transcripts. In developing animals, oligodendrocytes were strongly labelled with the janusin anti-sense cRNA probe during the period of myelination. The number of labelled cells and intensity of the hybridization signal decreased significantly with increasing age. Interestingly, expression of janusin was not confined to oligodendrocytes. Some neuronal cell types and type-2 astrocytes present in optic nerve cell cultures also contained janusin transcripts. In contrast to oligodendrocytes, the number and labelling intensity of neurons containing janusin transcripts remained constant during postnatal development and into adulthood. Expression of janusin protein in the spinal cord was developmentally regulated, with a peak of expression in 2- or 3-week-old animals. The molecule was visible in the white and grey matter. In myelinated regions, it was associated with myelinated fibres and accumulated at nodes of Ranvier. These observations suggest that janusin may be of functional relevance for myelination.

Aging↗
PubMed1991

Ontogeny of growth hormone releasing hormone and insulin-like growth factors-I and -II messenger RNA in rat placenta.

Hypothalamic growth hormone releasing hormone (GHRH) stimulates pituitary growth hormone secretion, which is essential for normal postnatal growth. Reports of an immunoreactive and biologically active GHRH-like peptide in placenta led us to investigate placental expression of GHRH mRNA. Placentas from d 19 gestation fetal rats were assayed for GHRH-like peptide by ELISA and for GHRH mRNA. Placenta GHRH-like peptide levels averaged 3.7 +/- 0.2 ng/g tissue. Dot-blot hybridization revealed the presence of GHRH mRNA in rat placenta in quantities greater than those of the message in rat hypothalamus. Northern gel analysis of poly-A enriched RNA was used to evaluate the specificity of GHRH mRNA hybridization and to determine the size of the placental mRNA. Placental and hypothalamic GHRH mRNA were of nearly identical size, although placental RNA had a broad band of hybridization that extended below that seen in hypothalamus. Further confirmation of homology between placental and hypothalamic GHRH mRNA was determined by an RNAse protection assay, in which a placental protected fragment was identical in size to that resulting from protection of the hypothalamic complementary RNA. The ontogeny of GHRH mRNA in rat placenta was determined by dot-blot hybridization. The message was detected at the earliest date examined, d 7, and increased more than 2-fold by d 14 and 5-fold by d 17. The ontogeny of IGF-I and IGF-II mRNA in placenta was also determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

Androgen receptor gene expression in rat granulosa cells: the role of follicle-stimulating hormone and steroid hormones.

In rat ovary, androgen receptor (AR) is predominantly expressed in granulosa cells and is developmentally regulated. However, the exact mechanism that is responsible for the regulation of AR in granulosa cells has not been elucidated. The aim of this study was to examine 1) the levels of AR messenger RNA (mRNA) expression in granulosa cells from follicles of different size and 2) the effects of FSH, 8-bromo-cAMP, androgen, and estrogen on AR mRNA levels in granulosa cells in vitro. The abundance of AR mRNA was examined by ribonuclease protection assay using 32P-labeled AR complementary RNA probe and related to that of P450aromatase (P450arom) mRNA, a well established maker of granulosa cell differentiation. In large follicles (> 400 microns in diameter), the abundance of AR mRNA was decreased to 51% of that in small follicles (< 200 microns; P < 0.01), whereas the abundance of P450arom mRNA increased to 277% (P < 0.01). In medium follicles (200-400 microns), the abundance of AR mRNA was maintained (101%), whereas the abundance of P450arom mRNA increased to 202% of that in small follicles (P < 0.05). Treatment with FSH (0-300 ng/ml) or 8-bromo-cAMP (0-4 mM) induced P450arom mRNA in the cultured granulosa cells in a dose-dependent manner; however, it did not affect the levels of AR mRNA expression. Treatment with 5 alpha-dihydrotestosterone (1 microM) resulted in a significant reduction in the abundance of AR mRNA to 67% of the control value (P < 0.05). This effect was reversed by the addition of FSH (100 ng/ml; P < 0.01). Treatment with diethylstilbestrol (1 microM), alone or in combination with FSH (100 ng/ml), did not have any significant effect, although these treatments tended to decrease the abundance of AR mRNA to 81% and 85%, respectively. Both 5 alpha-dihydrotestosterone and diethylstilbestrol dramatically enhanced the abundance of FSH-induced P450arom mRNA compared to the effect of FSH alone. These results indicate that 1) the down-regulation of AR mRNA expression takes place in granulosa cells of preovulatory follicles; 2) FSH is not directly responsible for this event; and 3) androgen down-regulates AR mRNA expression in immature granulosa cells, and this effect is reversed by FSH. We conclude that androgen and FSH jointly regulate AR mRNA expression in rat granulosa cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1996

Endless quest.

The replication of linear chromosome DNA by DNA polymerase leads to the loss of terminal sequences, in the absence of a special mechanism to maintain ends or telomeres. This mechanism is known to consist of short terminal repeats and the enzyme telomerase, which contains RNA complementary to the DNA repeats. There is evidence that telomeric DNA continually decreases in size in the absence of telomerase, and this is followed by cellular senescence. Immortalisation of somatic cells is accompanied, at least in some cases, by acquisition of telomerase activity. The cloning of DNA coding for the RNA component of telomerase has opened up some new experimental approaches, including the study of telomerases with mutant RNA. The telomere theory of cellular senescence appears to provide a molecular basis for the 'Hayflick limit' to human fibroblast growth. However the telomeres and behaviour of primary mouse cells are anomolous, and many immortalised human cell lines lack normal telomerase activity. These exceptions are not easily accommodated in the telomere theory.

Animals↗
PubMed1996

The peptide-based thrombin inhibitor CRC 220 is a new substrate of the basolateral rat liver organic anion-transporting polypeptide.

The peptidomimetic thrombin inhibitor CRC 220, 4-methoxy-2,3,6-trimethylphenylsulfonyl-L-aspartyl-D-4-amidinop henylalanyl- piperidide, is taken up into isolated rat hepatocytes through active, carrier-mediated transport. This uptake is inhibited by bile acids. Functional expression in Xenopus laevis oocytes was performed to identify the transport system responsible for the hepatocellular CRC 220 uptake. Injection of poly(A)+RNA in X. laevis oocytes resulted in a two- to three-times higher uptake of CRC 220, compared with uninjected or water-injected control oocytes. Taurocholate (200 mumol/L) inhibited this uptake completely. No uptake of the peptidomimetic thrombin inhibitor was observed, when X. laevis oocytes were injected with complementary RNA (cRNA) encoding either the cloned rat liver Na(+)-dependent taurocholate transporter Ntcp, the renal oligopeptide carrier rhaPT or the intestinal oligopeptide transporter PepT1. However, after injection of cRNA of the cloned rat liver Na(+)-independent organic anion transporting polypeptide oatp, a specific and saturable CRC 220 uptake was observed (Michaelis-Menten constant 29.5 mumol/L). Cis-inhibition with known oatp-substrates, e.g., 20 mumol/L Bromsulphalein (BSP), 2007 mumol/L taurocholate and 2007 mumol/L cholate, occurred in oatp-expressing X. laevis oocytes, whereas substrates of the two peptide carriers as well as dipeptide- and single-amino acid constituents of the thrombin inhibitor itself lacked any significant inhibitory effects. These data show that the modified dipeptide CRC 220 is a highly selective substrate of the organic anion transporting polypeptide oatp in the basolateral plasma membrane of rat hepatocytes.

Animals↗
PubMed1983

Regulation of light-harvesting chlorophyll-binding protein (LHCP) mRNA accumulation during the cell cycle in Chlamydomonas reinhardi.

Light-harvesting chlorophyll a/b protein (LHCP) synthesis is highly regulated during the cell cycle in light-dark synchronized C. reinhardi cells. LHCPs are a family of cytoplasmically synthesized proteins which are imported into the chloroplast. LHCPs are derived from at least two precursor proteins (32 kd and 30 kd) that are synthesized in vitro and immunoprecipitated by antiserum against chlorophyll-protein complex II proteins. A DNA copy of the mRNA encoding a 32 kd LHCP precursor was cloned from cDNA synthesized from poly(A) RNA obtained from mid-light-phase synchronous cells. Using cloned cDNA (pHS16) as a hybridization probe, we found that a single 1.2 kb RNA complementary to pHS16 accumulates in a wave-like manner during the mid-light phase of the 12 hr light-12 hr dark cycle and correlates with the pattern of chlorophyll synthesis. Light, during the light phase in the light-dark cycle, is required for accumulation of this RNA.

Cell Cycle↗
PubMed1996

Investigation of some properties of oligodeoxynucleotides containing 4'-thio-2'-deoxynucleotides: duplex hybridization and nuclease sensitivity.

The thermal stabilities of the duplexes formed between 4'-thio-modified oligodeoxynucleotides and their DNA and RNA complementary strands were determined and compared with those of the corresponding unmodified oligodeoxynucleotides. A 16mer oligodeoxynucleotide containing 10 contiguous 4'-thiothymidylate modifications formed a less stable duplex with the DNA target (deltaTm/modification -1.0 degrees C) than the corresponding unmodified oligodeoxynucleotide. However, when the same oligodeoxynucleotide was bound to the corresponding RNA target, a small increase in Tm was observed (deltaTm/modification +0.16 degrees C) when compared with the unmodified duplex. A study to identify the specificity of an oligodeoxynucleotide containing a 4'-thiothymidylate modification when forming a duplex with DNA or RNA containing a single mismatch opposite the modification found the resulting Tms to be almost identical to the wild-type duplexes, demonstrating that the 4'-thio-modification in oligodeoxynucleotides has no deleterious effect on specificity. The nuclease stability of 4'-thio-modified oligodeoxynucleotides was examined using snake venom phosphodiesterase (SVPD) and nuclease S1. No significant resistance to degradation by the exonuclease SVPD was observed when compared with the corresponding unmodified oligodeoxynucleotide. However, 4'-thio-modified oligodeoxynucleotides were found to be highly resistant to degradation by the endonuclease S1. It was also demonstrated that 4'-thio-modified oligodeoxynucleotides elicit Escherichia coli RNase H hydrolysis of the RNA target only at high enzyme concentration.

DNA↗
PubMed1997

The origin of the genetic code and protein synthesis.

A model for a parallel evolution of the genetic code and protein synthesis is presented. The main tenet of this model is that the genetic code, that is, a correspondence between nucleotide and amino-acid coding units, originated from sequence-specific interaction between abiotically synthesized polynucleotides and polypeptides. A sequence-specific binding between oligonucleotides and oligopeptides is supported by experimental findings. Moreover, it is parsimonious enough to be consistent with the relatively simple chemistry of a primordial environment. Proximity between peptides and RNA increased the rate of formation of ester bonds between them. This lead to the accumulation of sequence-specific polypeptide-polynucleotide pairs, that is, of primordial-loaded tRNA. Condensation of short polypeptides into longer products could be catalyzed by a sequence-specific juxtaposition of loaded tRNA over complementary RNA, originating the core of protein synthesis. The accumulation of useful encoded products, for example, catalysts for tRNA loading (primordial aminoacyl-tRNA synthetases) or stabilizers of tRNA-mRNA interactions (primordial ribosomes), permitted the subsequent evolution of protein synthesis and of the genetic code to their mature form. This occurred via a parallel reduction in length of the interacting polynucleotides and polypeptides. Thus, it maintained the correct reading frame of mRNA from the preceding stages of evolution.

Evolution, Molecular↗
PubMed1998

Inhibition of human telomerase by 2'-O-methyl-RNA.

Telomerase, a ribonucleoprotein up-regulated in many types of cancers, possesses an RNA template necessary to bind and extend telomere ends. The intrinsic accessibility of telomerase to incoming nucleic acids makes the RNA template an ideal target for inhibition by oligonucleotides. We report here that 2'-O-methyl-RNA (2'-O-meRNA), an oligonucleotide chemistry known to exert sequence-specific effects in cell culture and animals, inhibits telomerase with potencies superior to those possessed by analogous peptide nucleic acids (PNAs). Potent inhibition relative to PNAs is surprising, because the binding affinity of 2'-O-meRNAs for complementary RNA is low relative to analogous PNAs. A 2'-O-meRNA oligomer with terminal phosphorothioate substitutions inhibits telomerase sequence-selectively within human-tumor-derived DU145 cells when delivered with cationic lipids. In contrast to the ability of 2'-O-meRNA oligomers to inhibit telomerase, the binding of a 2'-O-meRNA to an inverted repeat within plasmid DNA was not detectable, whereas binding of PNA was efficient, suggesting that the relative accessibility of the telomerase RNA template is essential for inhibition by 2'-O-meRNA. Inhibition of telomerase by 2'-O-meRNA will facilitate probing the link between telomerase activity and sustained cell proliferation and may provide a basis for the development of chemopreventive and chemotherapeutic agents.

Amino Acid Sequence↗
PubMed1996

Expression of cytokeratin messenger RNA versus protein in the normal mammary gland and in breast cancer.

It is not known how tightly regulation of cytokeratin (CK) protein expression is correlated with transcriptional activity in breast cancer. The level of control of CK expression in the normal mammary gland and in breast cancer has been assessed by combining in situ hybridization with riboprobes, and with immunohistochemistry using monospecific antibodies. In normal mammary gland, luminal cells showed abundant hybridization with complementary RNA (cRNA) probes for CK7, CK8, CK18, and CK19. Proteins of these CKs were correspondingly distributed except for that of CK19, which showed a heterogeneous staining. In primary carcinomas, both messenger RNAs (mRNAs) and proteins of CK8 and CK18 were generally expressed to a degree similar to that of normal epithelia, but a lower level of mRNA and protein of CK18 was observed in metastatic carcinomas. Reduced expression of CK7 and CK14 was observed in all carcinomas, and the correlation between mRNA and protein for these two cytokeratins was unbalanced, whereas the expression of CK19 mRNA and the proportion of its protein-positive cells were increased. The results suggest that these major CKs in normal mammary gland epithelia are regulated at the transcriptional level except for CK19, which is partially under the posttranscriptional control. The alterations observed in breast cancer are not only reflected by the reduced or increased expression of individual cytokeratins, but characterized by partial loss of the normal regulation of cytokeratin expression.

Adult↗
PubMed1977

Specificity of initiation of transcription of simian virus 40 DNA I by Escherichia coli RNA polymerase: identification and localization of five sites for initiation with [gamma-32P]ATP.

Simian virus 40 (SV40) DNA I was transcribed with Escherichia coli RNA polymerase in the presence of gamma-32P-labeled ribonucleoside triphosphates in order to investigate the specificity of initiation of in vitro transcription. ATP and GTP served as predominant initiating nucleotides, the former being incorporated about twice as much as the latter. Cleavage of [gamma-32P]ATP-labeled SV40 complementary RNA (cRNA) with T1 RNase followed by homochromatographic analysis of the resultant 5' initiation fragments revealed the presence of four specific initiation fragments 6 to 9 nucleotides in length, designated AI, AII, AIIIa, and AIIIb. By means of hybridization of [gamma-32P]ATP-labeled SV40 cRNA to DNA from specific adenovirus 2-SV40 hybrids and specific restriction endonuclease fragments of SV40 DNA before chromatographic analysis, it was possible to identify and determine approximate localizations of five [gamma-32P]ATP initiation sites on the SV40 genome: one in Hin-G close to the Hin-G-B junction, giving rise to the AII fragment, two in the overalpping fragment Hin-A-Hae-A,giving rise to AI and AIII fragments, and two in the fragment Hin-A-Hae-E, also giving rise to AI and AIII fragments. All five sites either fall within or lie near regions of the genome that are cleaved by S1 nuclease and subject to partial alkaline denaturation. These five sites lie on the minus strand of SV40 DNA and initiate RNAs that are copied in a leftward direction. Cleavage of [gamma-32P]GTP-labeled cRNA with pancreatic RNase liberated three major 5' initiation fragments of short length, GI, GII, and GIII, suggesting the presence of three principal GTP initiation sites.

Adenosine Triphosphate↗
PubMed2004

The dopamine precursor L-dihydroxyphenylalanine is transported by the amino acid transporters rBAT and LAT2 in renal cortex.

The intrarenal autocrine-paracrine dopamine (DA) system is critical for Na(+) homeostasis. l-Dihydroxyphenylalanine (l-DOPA) uptake from the glomerular filtrate and plasma provides the substrate for DA generation by the renal proximal tubule. The transporter(s) responsible for proximal tubule l-DOPA uptake has not been characterized. Renal cortical poly-A(+) RNA injected into Xenopus laevis oocytes induced l-DOPA uptake in a time- and dose-dependent fashion with biphasic K(m)s in the millimolar and micromolar range and independent of inward Na(+), K(+), or H(+) gradients, suggesting the presence of low- and high-affinity l-DOPA carriers. Complementary RNA from two amino acid transporters yielded l-DOPA uptake significantly above water-injected controls the rBAT/b(0,+)AT dimer (rBAT) and the LAT2/4F2 dimer (LAT2). In contradistinction to renal cortical poly-A(+), l-DOPA kinetics of rBAT and LAT2 showed classic Michaelis-Menton kinetics with K(m)s in the micromolar and millimolar range, respectively. Sequence-specific antisense oligonucleotides to rBAT or LAT2 (AS) caused inhibition of rBAT and LAT2 cRNA-induced l-DOPA transport and cortical poly-A(+)-induced arginine and phenylalanine transport. However, the same ASs only partially blocked poly-A(+)-induced l-DOPA transport. In cultured kidney cells, silencing inhibitory RNA (siRNA) to rBAT significantly inhibited l-DOPA uptake. We conclude that rBAT and LAT2 can mediate apical and basolateral l-DOPA uptake into the proximal tubule, respectively. Additional l-DOPA transport mechanisms exist in the renal cortex that remain to be identified.

Amino Acid Transport System y+↗
PubMed1981

Cytochemical hybridization with fluorochrome-labeled RNA. I. Development of a method using nucleic acids bound to agarose beads as a model.

A new procedure to label RNA at the 3'-terminus with a fluorochrome molecule is described. The thiosemicarbazides derived from tetramethylrhodamine isothiocyanate (TRITC) and fluorescein isothiocyanate (FITC) were prepared by reacting these compounds with hydrazine in dimethylsulfoxide (DMSO):pyridine, 99:1 (v/v). They coupled efficiently to the aldehydes generated by periodate oxidation of RNAs. We determined, using Sepharose to which different nucleic acids and proteins had been bound, that the label added no specific binding properties to the RNA, and did not interfere with duplex formation of labeled poly(U) and poly(A). The stability of the fluorochrome-RNA bond under conditions generally used for hybridization was investigated. The bond was found to be unstable at 66 degrees C in 3 x SSC, 0.1% SDS (50% loss within 45 min) but stable for at least 40 hr at 23 degrees C in 70% formamide/3 x SSC. The hybridization characteristics of complementary RNA, both fluorochrome- and 3H-labeled, were investigated using DNA-Sepharose beads as a cytochemical model. Hybridization was measured by scintillation counting of microliter quantities of beads and quantitative fluorescence microscopy of individual Sepharose beads. No influence of the label on the specificity and stability of the hybrids was found. Maximum specific fluorescence was found after hybridization at 23 degrees C in 70% formamide/3 x SSC. These results made possible the successful use of fluorochrome-labeled RNA to perform cytochemical hybridization followed by detection of the hybrids with fluorescence microscopy. This will be described in an accompanying article.

Coloring Agents↗
PubMed2005

Induced fit and "lock and key" recognition of 5S RNA by zinc fingers of transcription factor IIIA.

Transcription factor IIIA (TFIIIA) is a Cys2His2 zinc finger protein that regulates expression of the 5 S ribosomal RNA gene by binding specifically to the internal control element. TFIIIA also functions in transport and storage of 5 S RNA by binding directly to the RNA transcript. To obtain insights into the mechanism by which TFIIIA recognizes 5 S RNA, we determined the solution structure of the middle three zinc fingers bound to the central core of 5 S RNA. Finger 4 utilizes "lock and key" recognition to bind in the widened major groove of the pre-structured RNA loop E motif. This interaction is mediated by direct hydrogen bonding interactions with bases. In contrast, recognition of loop A, a flexible junction of three helices, occurs by an induced fit mechanism that involves reorganization of the conserved CAUA motif and structuring of the finger 5-finger 6 interface to form a complementary RNA binding surface.

Amino Acid Sequence↗
PubMed1977

The definition of a large viral transcription unit late in Ad2 infection of HeLa cells: mapping by effects of ultraviolet irradiation.

The synthesis of Ad2-specific nuclear RNA in HeLa cells 15 hr post-infection has been examined after ultraviolet irradiation. The synthesis of RNA complementary to various segments of Ad2 DNA is decreased differentially, with the most sensitive region at the right end of the physical map and the most resistant in the region from 0 up to 0.2-0.3 (20-30% from the left end of the genome). For a given ultraviolet dose, the amount of labeled RNA homologous to various DNA fragments decreased exponentially from map position 0.2-0.3 to 1.0. These results suggest that a major transcriptional unit late in Ad2 infection is a rightward-transcribing unit between 0.0-0.3 and 1.0.

Adenoviruses, Human↗
PubMed1989

Intervening sequence-specific in situ hybridization: detection of the pro-opiomelanocortin gene primary transcript in individual neurons.

We describe here the in situ hybridization procedure which we have used to detect the pro-opiomelanocortin (POMC) gene primary transcript in nuclei of individual neurons in the periarcuate region of the hypothalamus. An exon-intron RNA probe was used to detect POMC primary transcript and mature mRNA in nuclear extracts of nucleic acids using a sensitive S1 nuclease protection assay. The levels per cell of nuclear primary transcript were similar to those seen in the anterior pituitary, suggesting that intervening sequence in situ hybridization should be feasible. A nonrepetitive complementary RNA probe specific for the first intervening sequence of the rat POMC gene (POMC IVS-A) was used to detect the POMC primary transcript in hypothalamic tissue sections by in situ hybridization. The distribution of nuclear localized autoradiographic grains was similar to that previously reported for immunocytochemically defined POMC neurons, suggesting that the procedure is also effective in brain cells.

Arcuate Nucleus of Hypothalamus↗
PubMed2002

Chromomycin A3 inhibits influenza a virus multiplication in chick embryo fibroblast cells.

The multiplication of Ulster 73 virus, an avian strain of type A influenza virus, was blocked in chick embryo fibroblast cells, CEF, by treatment with 0.5 microg/ml of chromomycin A3 whereas in LLC-MK2 cells no inhibition of replication was observed. Virus-induced polypeptide synthesis in chick embryo fibroblast cells was confined to the synthesis of PB2, PB1 and PA subunits of the RNA dependent-RNA polymerase, the nucleoprotein NP, the non-structural protein NS1, the haemagglutinin HA, the non-structural protein NS2; only the membrane M1 polypeptide synthesis was greatly inhibited. Viral unpolyadenylated cRNAs synthesis was studied at a late time of the infection, 8 hours p.i.: chromomycin A3 was able to inhibit the "novo" synthesis of complementary RNA poly(A)- and segment 7 of virion RNA. The mode of action of the drug in chick embryo fibroblast cells is discussed.

Animals↗