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At least 991 records · Page 55Linked to original sources
PubMed1994

Induction of prostaglandin endoperoxide synthase-2 by human chorionic gonadotropin in bovine preovulatory follicles in vivo.

Gonadotropins have recently been shown to induce prostaglandin endoperoxide synthase-2 (PGHS-2) in rat preovulatory follicles before ovulation, but hormonal induction of this enzyme has not yet been reported in preovulatory follicles of any other species. To determine whether the selective induction of PGHS-2 by the ovulatory gonadotropin surge is a molecular process that has been conserved in other mammalian species with different reproductive cycles, the regulation of PGHS isoforms was studied in bovine preovulatory follicles isolated 0, 6, 12, 18, 20, 22, 24, and 26 h after an ovulatory dose of hCG. Each follicle was dissected into three preparations: the intact follicle wall (i.e. theca interna with attached granulosa cells), theca interna, and isolated granulosa cells. Solubilized cell extracts were obtained from each preparation and analyzed by Western blots, using polyclonal antibodies that selectively recognize PGHS-2 and PGHS-1 isoforms. RNA extracts were prepared and analyzed by Northern blots, using a mouse PGHS-2 complementary DNA. The results indicated that the expression of PGHS-2 messenger RNA (mRNA) and protein, but not that of PGHS-1, was regulated by hCG in bovine preovulatory follicles before ovulation. Levels of PGHS-2 protein (mol wt, 74,000) in the follicle wall were undetectable at 0, 6, and 12 h, but increased dramatically after 18 h to reach maximal levels 24 h post-hCG treatment. Northern blots revealed a similar temporal induction of PGHS-2 mRNA (4.0 kilobases). Analyses of isolated preparations of theca interna and granulosa cells clearly showed that PGHS-2 was expressed exclusively in granulosa cells and not in theca interna. Significant increases in follicular fluid concentrations of prostaglandins E2 and F were associated with the induction of follicular PGHS-2 protein and mRNA. Thus, this study establishes that the induction by gonadotropin of PGHS-2 in granulosa cells before ovulation appears to be a conserved mechanism by which the synthesis of prostaglandins necessary for the ovulation process is regulated in different species. However, the striking difference between the time course of PGHS-2 induction previously reported in rat follicles (4 h post-hCG treatment) and that observed in bovine follicles (18 h post-hCG treatment) suggests that the control of PGHS-2 expression could be one of the determinants involved in dictating the species-specific progression (length) of the ovulation process.

Animals↗
PubMed1976

Feline calicivirus: purification of virus and extraction and characterisation of its ribonucleic acid.

Purification of feline calicivirus was achieved by cycles of differential centrifugation and two cycles of sucrose gradient centrifugation. Feline calicivirus grown in the presence of Actinomycin D and 3H-uridine-5, sediments in 15% to 45% sucrose gradients and forms a peak of radioactivity which corresponds with the peak of infectivity. Ribonucleic acid (RNA) extracted from the peak radioactive fractions taken from the sucrose gradient sedimented as a single peak ahead of the 28S peak of cellular RNA. It was sensitive to ribonuclease and was presumed to be single stranded feline calicivirus RNA with sedimentation of 32S-35S. A single peak of radioactivity at 35S was extracted from purified virus by heating at 60 degrees for two minutes in 1% sodium dodecyl sulphate (SDS), or by heating at 37 degrees for 5 minutes at 1% SDS. Virus extracted at 37 degrees for 10 minutes in 1% SDS showed also a small peak at 16S and by 15 minutes at 37 degrees only a broad peak at 16S occurred. All peaks were susceptible to ribonuclease. A component sedimenting at 18S which was resistent to degradation by ribonuclease under the conditions outlined by Baltimore (4) and presumed to be double-stranded RNA was present in kitten kidney cells infected with feline calicivirus.

Caliciviridae↗
PubMed1979

Characterization of an amber suppressor in Pneumococcus.

Partial revertant has been isolated, with resistance to aminopterin intermediate between wild type and mutant. This phenotype is the result of a mutation at a gene unlinked to the amiA locus. This suppressor mutation (su+) has no phenotypic characteristics by itself except a slow growth. 9 amiA mutants (belonging to 6 sites) are affected by su+ out of the 30 investigated mutants (i.e. 22 sites). The efficiency of suppression is site dependent. Two sites out of 14 mutants belonging to the thymidylate synthetase gene are suppressible. Thymidylate synthetase activity is partially restored by su+. Optochin mutants can also be suppressed. Thus su+ is not gene specific but site specific. Moreover when the str-41 allele conferring resistance to streptomycin is introduced by transformation, the suppression effect is restricted. All these properties are characteristic of an informational suppressor. The t-RNA extracted from the suppressor strain su+ but not the wild type restored the synthesis of coat protein coded by RNA from an amber mutant of bacteriophage f2. Attempts to detect ochre suppression activity gave negative results. It is suggested that the su+ gene is amber specific. Thus su+ can provide insight into the nature of suppressible mutations which should be point mutations. Both low efficiency and high efficiency mutants are affected by su+; this is additional evidence that both categories contain point mutations.

Alleles↗
PubMed1988

RNA transcripts of Marek's disease virus (MDV) serotype-1 in infected and transformed cells.

RNA was isolated from two strains of Marek's disease virus (MDV-Z and MDV-B). The virus was grown in duck embryo fibroblasts (DEF) for 96 hr, 72 hr in the presence of phosphonoacetic acid (PAA) and 24 hr in the presence of cycloheximide added at the time of infection. With the use of DNA probes representing about 80% of the MDV genome, an extensive Northern blot analysis of the RNA was carried out. A similar analysis was done with RNA extracted from the MDV-transformed cell line MSB-1. This study revealed 42, 25 and 29 discrete viral RNA transcripts in MDV-Z and MDV-B-infected DEF and in the MSB-1 cell line, respectively, ranging in size from 0.8 to 13 kb. In MDV-Z-infected DEF, there were twelve late RNA species, two early and eight immediate-early viral transcripts. In MDV-B-infected DEF there were eleven late RNA species, two early and seven immediate-early viral transcripts. The RNA species were homologous for all the probes used except the BamHI-G DNA fragment where no RNA transcripts were detected in the MSB-1 cell line. The RNA transcripts were used to produce a preliminary viral RNA map. Comparison of the location and sizes of the viral RNA transcripts in MDV-infected and MDV-transformed cells revealed several differences.

Animals↗
PubMedDate not supplied

Identification of okadaic-acid-induced genes by mRNA differential display in glioma cells.

To identify novel genes associated with apoptosis in glioma cells, we treated T98G glioma cells with okadaic acid (OA). Differential display using 15 random primers was performed on RNA extracted from these cells. Upregulated bands were excised from polyacrylamide gels and cloned. Northern blots were used to confirm RNA expression in T98G cells. 18 RNA fragments corresponding to the untranslated region of genes were identified and sequenced. Three unknown gene fragments were used to screen a fetal brain cDNA library resulting in three complete cDNA sequences. The three sequences corresponded to a human gene homologous to the yeast translation initiation factor Sui-1, a cAMP-regulated phosphoprotein, ARPP-16/19, and a novel gene designated O48. Transcription of Sui-1 increased in response to all stress factors tested, whereas ARPP only responded to OA. 2-kb and 4-kb O48 RNA species were identified. OA and stress factors increased 2-kb expression while K252a (protein kinase inhibitor) increased 4-kb expression. Differential display is effective for identifying genes associated with apoptosis. Novel genes may be identified by further analysis of the gene fragments identified in this study. The function of O48 is unknown.

Amino Acid Sequence↗
PubMed1979

The transcript from a DNA puff of Rhynchosciara and its migration to the cytoplasm.

Electrophoretic analysis of 3H-RNA obtained from the proximal sections of Rhynchosciara salivary glands at two distinct developmental periods, one characterized by the presence and the other by the absence of the giant B-2 DNA puff, revealed that the appearance of a 14S poly(A)+ RNA is correlated with the opening of this puff. That this RNA species is transcribed from this puff is indicated by the fact that it is found in RNA extracted from B-2 puffs obtained by microdissection. This confirmed by the specific hybridization of the 14S poly(A)+ RNA to the B-2 locus. Our data indicate that the polyadenylation process takes place at the chromosome level, and that the nuclear sap is not an important compartment in the transport of polyadenylated RNA from the chromosome to the cytoplasm. The kinetics of migration of the 14S species to the cytoplasm were studied; the data indicate that this process is very rapid and, in addition, that the 14S RNA is unstable.

Animals↗
PubMed1990

The detection and differentiation of foot-and-mouth disease viruses using solid-phase nucleic acid hybridization.

Thirteen complementary DNA (cDNA) probes were used to detect the presence of foot-and-mouth disease virus (FMDV) RNA extracted from cell cultures. When labelled with 32P, these probes enabled the detection of 1 pg of FMDV-RNA, or 1 virus copy per cell. Two FMDV A12 probes that coded for the leader, structural protein VP1 region and part of the polymerase gene respectively, showed no hybridization with other closely related picornaviruses. Differentiation between FMDV serotypes A, O and C was possible, using cDNA probes from individual serotypes that corresponded to structural protein VP1.

Aphthovirus↗
PubMed1996

A rapid and sensitive dot-blot hybridization assay for the detection of citrus exocortis viroid in Citrus medica with digoxigenin-labelled RNA probes.

A rapid and sensitive dot-blot hybridization assay using in vitro-transcribed digoxigenin-labelled RNA probes (riboprobes) was developed aiming at detection of citrus exocortis viroid (CEVd) in crude sap of infected Citrus medica plants. The protocol includes a very quick and simple preparation of RNA extracts from samples using a denaturation step with formaldehyde. From our results, the employment of this step is highly recommended because the hybridization signals in formaldehyde-denatured samples were significantly stronger when compared with that of extracts without formaldehyde treatment. The assay was found to be sensitive enough to detect 0.1 ng of purified CEVd RNA and was able to detect viroid in 0.2 mg of symptomatic Citrus medica leaves. The use of riboprobes also allowed hybridization under high temperature conditions, avoiding non-specific background.

Digoxigenin↗
PubMed2006

Tissue preferential expression of estrogen receptor gene in the marine snail, Thais clavigera.

Sex steroid hormones have been widely detected in molluscs, and experiments have shown the importance of sex steroids in sex determination, gonadal tissue maturation and gametogenesis. Nevertheless, the signaling pathways of sex steroids in invertebrates have not yet been elucidated. In order to gain insights into the mechanism of sex steroid signaling in molluscs, we have, therefore, tried to isolate molluscan estrogen receptors from the prosobranch mollusc Thais clavigera. Cerebral ganglia of T. clavigera (Mollusca, Gastropoda, Prosobranchia) were subjected to RNA extraction, and degenerate primers for amino acid sequences conserved in vertebrate estrogen receptors were designed. PCR amplification using cerebral RNA and degenerate primers followed by 5'- and 3'-RACE identified the cDNA encoding T. clavigera estrogen receptor 1 (tcER1). The deduced amino acid sequence showed 93% identity in the DNA-binding domain and 72% identity in the ligand binding domain when compared to Aplysia estrogen receptor. Reporter gene assay revealed that tcER1 is constitutively active and unresponsive to estrogen. Quantitative analysis of the tcER1 mRNA level demonstrated the preferential expression in the ovary. Furthermore, cerebral ganglia expressed tcER1 at a high level in the spring followed by subsequent enlargement of the ovary in later seasons. These results suggest importance of tcER1 in the seasonal development of reproductive organs in T. clavigera.

Amino Acid Sequence↗
PubMed2002

Age-related changes in hypothalamic gonadotropin-releasing hormone and N-methyl-D-aspartate receptor gene expression, and their regulation by oestrogen, in the female rat.

During reproductive ageing, the oestrous cycles of female rats become irregular and eventually cease. The mechanisms for reproductive senescence in rodents are believed to involve changes in hypothalamic neurones, including gonadotropin-releasing hormone (GnRH) cells and their afferent inputs. In addition, effects of oestrogen on hypothalamic function may vary in animals of different ages. These issues were addressed using young (aged 4-5 months), middle-aged (12-14 months) and old (24-26 months) female Sprague-Dawley rats. Animals were ovariectomized and given oestrogen or vehicle replacement. They were killed and the preoptic area-anterior hypothalamus (POA-AH) and the medial basal hypothalamus-median eminence (MBH-ME) were dissected out, RNA extracted, and RNase protection assay used to quantify gene expression of several hypothalamic molecules. In the first experiment, GnRH RNA levels were measured in the POA-AH. No effects of ageing or oestrogen were observed on GnRH gene expression. This finding suggests that ageing and oestrogen may affect GnRH release from neuroterminals independently of de novo biosynthesis, and that this may involve other neurones that affect GnRH neurosecretory function. In the second experiment, we investigated changes in N-methyl-D-aspartate (NMDA) receptor subunit mRNA levels. These receptors play an important regulatory role in mediating effects of glutamate on GnRH function, and are themselves regulated by oestrogen and ageing. NMDA receptor subunit (NR) 1, 2a and 2b mRNA levels were quantified in the POA-AH and MBH-ME, the sites of GnRH perikarya and neuroterminals, respectively. In general, oestrogen had inhibitory effects on NR1 and NR2a, and differential effects on NR2b subunit mRNA levels. NMDA receptor subunit mRNA levels also changed during ageing: age-related decreases in NR1 mRNA occurred in the MBH-ME, and an age-related increase in NR2b mRNA occurred in the POA-AH. Taken together, these results demonstrate subunit- and region-specific changes in hypothalamic NMDA receptor subunit gene expression with oestrogen and ageing. These alterations could have implications for the physiological effects of glutamate on its NMDA receptor, and impact the regulation of reproductive and other neuroendocrine and autonomic functions by hypothalamic glutamatergic inputs.

Aging↗
PubMed1981

Highly conserved glucose-regulated protein in hamster and chicken cells: preliminary characterization of its cDNA clone.

A temperature-sensitive mutant K12 derived from a Chinese hamster fibroblast has been shown to overproduce three specific proteins of Mr 94,000, 78,000, and 58,000 when incubated at the nonpermissive temperature (40.5 degrees C). We previously identified these proteins as glucose-regulated proteins similar to those observed in chicken embryo fibroblasts when the cells are starved of glucose. In this report, we show that the Mr 78,000 proteins isolated from the hamster K12 cell line and from chicken embryo fibroblasts have identical electrophoretic mobilities in two-dimensional isoelectric focusing gels and nearly identical peptide maps. However, these proteins are different from heat-shock proteins previously described for animal cells. We have constructed a library of cDNA clones by using the RNA extracted from the hamster K12 cells incubated at 40.5 degrees C. Clones that hybridize preferentially with cDNA made from RNA at 40.5 degrees C were selected. By using the hybrid-selection technique, followed by in vitro translation, a cDNA clone containing a 2550-nucleotide insert coding for the hamster Mr 78,000 protein has been identified.

Animals↗
PubMed1976

Effect of ribonuclease T1 on ribosomal subunits of rat liver.

The accessibility of 28S RNA within the ribosomal subunits to ribonuclease T1 was studied, in comparing results obtained after enzyme treatment of compact, K+ deficient 60S subunits and of EDTA-treated 60S subunits. RNA, extracted from the subunits, using a mixture of sodium dodecyl sulfate and phenol was analyzed on sucrose gradients. The RNA from active subunits was only degraded in high enzyme concentrations. In the K+ deficient subunits, RNA is more accessible since it breaks down into 6 well-defined fragments, sedimenting between 4S and 18.5S. Within the EDTA-subunits, there is no more protection of the RNA. In fact, it is degraded by weak enzyme concentrations, as is the free 28S RNA, giving heterogeneous fragments. Comparison of the melting curves of subunits and free 28S RNA showed that it is only in EDTA subunits that proteins do not stabilize the secondary structure of RNA. In the case of 40S subunits, the action of ribonuclease T1 combines with the action of the endogenous nuclease which makes the degradation process more difficult to analyze.

Animals↗
PubMed1975

Thyroglobulin messenger RNA: translation of a 33-S mRNA into a peptide immunologically related to thyroglobulin.

Poly(UC)--Sepharose chromatography of the RNA extracted from a thyroid fraction sedimenting between 800 X g and 27000 X g allows the purification of two RNA fractions amounting each to 1% of the applied material. The first one is loosely bound to the column from which it is eluted at 25 degrees C. It is mainly composed of 16-S and 12-S RNA comprising no poly(A) sequences. This could correspond to mitochondrial rRNA. The second one, which is eluted at 50 degrees C, is poly(A)-rich and represents 33-S and 17--18-S RNA species. The 33-S RNA resists heating at 80 degrees C, suggesting that it is composed of one polynucleotide chain. When injected into Xenopus oocytes, the 33-S RNA specifically promotes the synthesis of a peptide with an apparent molecular weight of 185000 and an apparent sedimentation coefficient of 10-S. This peptide is immunologically related to thyroglobulin and could represent its main precursor. Under the conditions tested it does not polymerize spontaneously into 19-S thyroglobulin, suggesting that assembly of the molecule could require specific, post-translational alterations of the precursor and/or the presence of additional lighter subunits.

Animals↗
PubMed1964

ANTIBODY PLAQUE FORMATION BY NORMAL MOUSE SPLEEN CELL CULTURES EXPOSED IN VITRO TO RNA FROM IMMUNE MICE.

Suspensions of normal spleen cells from nonimmune mice were treated in vitro with RNA extracted from spleen cells from donor mice immunized 4 days previously with sheep erythrocytes. Subsequent incubation of the RNA-treated cells in tissue culture medium at 37 degrees C for several days resulted in a marked increase in the number of localized zones of hemolysis ("antibody plaques") in relation to the number of viable cells plated in agar containing sheep erythrocytes and complement. Nonimmune cells maintained in tisse, culture medium did not form plaques after incubation with either RNA from Immune mice or ribonuclease-treated RNA from immune mice, or with RNA from non-immune donor mice, or from donors immunized with chicken erythrocytes or bovine serum albumin.

Animals↗
PubMed1967

Isolation of ribosome particles from meningopneumonitis organisms.

In ribonucleic acid (RNA) extracted by phenol and sodium dodecyl sulfate from purified reticulate bodies of meningopneumonitis (MP) organisms, 21S, 16S, and 4S RNA were found by sucrose density gradient sedimentation analysis. When purified reticulate bodies were homogenized by sonic treatment or by treatment with sodium deoxycholate and were fractionated by differential centrifugation, more than 50% of the RNA was recovered in the fraction which was sedimented by centrifugation at 105,000 x g for 2 hr, but not at 13,000 x g for 20 min. From homogenates prepared in this manner, 50S and 30S particles containing RNA were isolated by sucrose density gradient centrifugation. These 50S and 30S particles were also found in lysates of cytoplasmic fractions of infected cells which were labeled by (32)P during 17 to 17.5 hr or 15 to 18 hr after infection. The synthesis of 50S and 30S particles was not inhibited by actinomycin D. When infected cells were homogenized in the presence of 0.01 or 0.02 m MgCl(2), 70S particles were isolated instead of 50S and 30S particles. When dialyzed against low concentrations of MgCl(2), the 70S particles dissociated to 50S and 30S particles. The base ratio of the 70S particles is very similar to that of 16S plus 21S RNA. The characteristics of the 70S, 50S, and 30S particles suggest that these are ribosome particles, similar to bacterial ribosomes.

Bile Acids and Salts↗
PubMed1980

Herpes simplex virus thymidine kinase transcripts are absent from both nucleus and cytoplasm during infection in the presence of cycloheximide.

Nick-translated DNA from a recombinant plasmid containing the herpes simplex virus type 1 thymidine kinase gene was used as a probe for the synthesis of thymidine kinase RNA. The recombinant plasmid was generated by inserting the 3.5-kilobase fragment derived by BamHI digestion of herpes simplex virus type 1 DNA into plasmid pBR322. At 8 h after infection, cytoplasmic and nuclear RNA hybridized to 14% and 19% of the recombinant DNA probe, respectively. However, no significant hybridization was found with either nuclear or cytoplasmic RNA extracted from cells infected and maintained in the presence of cycloheximide. This suggests that no thymidine kinase-related RNA was synthesized in the absence of alpha polypeptides, and supports the hypothesis that the alpha polypeptides effect new thymidine kinase RNA synthesis rather than being involved in processing or transport of thymidine kinase RNA. In cells infected and maintained in the presence of the arginine analog canavanine, about 2 to 3% of the plasmid DNA was found to hybridize with cytoplasmic and nuclear RNA. However, when a recombinant plasmid DNA containing only thymidine kinase coding sequences was used, no significant hybridization was found. The inhibition of thymidine kinase transcription by canavanine suggests that thymidine kinase belongs to the beta 2 kinetic class.

Canavanine↗
PubMed1984

Structure of the transforming region of human cytomegalovirus AD169.

The minimum size fragment of human cytomegalovirus AD169 required to initiate transformation was determined by transfection of primary rat embryo cells with deletion fragments constructed by digestion of a cloned fragment containing the transforming region (pCM4000) with exonuclease III and S1 nuclease. The results indicate that the left-hand boundary of the minimum size sequence for transformation must reside between 490 and 318 bases from the HindIII site of pCM4000. The right-hand boundary was defined by the EcoRI site which is 20 bases from the HindIII site. The nucleotide sequence of the transforming fragment of human cytomegalovirus was determined by the chemical degradation technique of Maxam and Gilbert and with the dideoxynucleoside triphosphate chain termination method. The sequence of pCM4000 comprises 2,848 base pairs and has an A X T composition of 59.5%. Reading frame analysis of the sequence indicated the longest open reading frame was 118 amino acids in length. Northern blot analysis of polyadenylated and non-polyadenylated RNA extracted from cells at immediate early and late times after infection with human cytomegalovirus indicate that one 5.0-kilobase RNA species hybridized to pCM4000 (Jahn et al., J. Virol, in press). The direction of transcription was determined by hybridization of this transcript with M13 single-stranded probes, and S1 analysis of this RNA did not detect introns.

Base Sequence↗
PubMed1998

Expression and cellular localization of keratinocyte growth factor and its receptor in human hyperplastic prostate tissue.

It is well recognized that the actions of androgens alone do not explain the hyperplastic development of the gland that occurs in elderly men. The increasing number of reports confirming the lack of mitogenic activity of androgens coupled with the powerful mitogenic activity of growth factors and the discovery of growth factor receptors led to an increased interest in the putative role of growth factors in prostate physiopathology. We have previously demonstrated the presence and the cellular localization of epidermal growth factor and of the related peptide, transforming growth factor-alpha, together with their common receptor in the epithelial compartment of the human hyperplastic prostate tissue (BPH). In the present study we examined the expression and cellular localization of messenger ribonucleic acid (RNA) encoding keratinocyte growth factor (KGF) and its receptor in human hyperplastic prostate tissue. RT-PCR of total RNA extracted from BPH tissues documented the presence of transcripts for KGF and its receptor. In situ hybridization with specific RNA probes synthesized from the respective complementary DNA demonstrated that KGF mRNA was mainly localized in the stromal cells, whereas its receptor was mainly localized in the prostate epithelium. Moreover, the mitogenic activity of KGF on cultured BPH cells compared to that of other growth factors has been tested. Our findings clearly indicate that KGF has the ability to function as a potent mitogen in BPH cells. Our data support the hypothesis that KGF plays an important role in prostate growth and that in human prostate it seems to act in a paracrine fashion.

Cell Division↗