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At least 883 records · Page 49Linked to original sources
PubMed1975

[Ribonuclease activity following partial hepatectomy in the liver of healthy and alloxan diabetic rats and histological findings in the islets of Langerhans (author's transl)].

QUESTION: What changes in the level of ribonuclease activity (RNase activity) can be observed in the regenerating liver of healthy and alloxan diabetic rats following partial hepatectomy? What coincidental alterations of the ratio A-cells to B-cells do occur in the islets of Langerhans? MATERIALS AND METHODS: 120 male Wistar rats of averagely 180 g body weight were fed a standard diet ("Rehbrücke") with drinking water ad libitum. After deprivation of food for 15 hours the animals were sacrificed by heart puncture under ether anesthesia. The caudal part of the body was rinsed free from blood by ice-cooled physiological saline via the aorta. After removal of the livers each 2 g of liver tissue were homogenized in 0.25 M saccharose or 70% ethyl alcohol. For the study of impairment of ribonuclease activity in the liver following different lesions the animals were divided into 3 test groups of 35 animals each: group 1: alloxan diabetes; group 2: liver regeneration after partial hepatectomy; group 3: alloxan diabetes in combination with liver regeneration after partial hepatectomy. From each group always 4 to 6 animals were sacrificed at the following time intervals: 2nd day and 4th day as well as after 3, 4 and 6 weeks. In 8 animals the enzymatic activity was not influenced. RNA content and dry weight of the livers of all test animals were determined. In liver homogenates with saccharose the ribonuclease activity was measured according to the method of FIERS (1961) using highly purified yeast RNA for substrate. This technique is especially suitable for raw tissue homogenates. After 30 min incubation at 37 degrees C and precipitation of the high-molecular polynucleotides as well as of protein by means of methylglycol and barium perchlorate the not precipitable low-molecular oligonucleotides which were produced by ribonuclease action, were spectrophotometrically measured in the supernatant at 260 nm. The deltaE-value was calculated for the employed quantity of RNA related to mg of protein brought into action. Demonstration and determination of the ribonuclease inhibitor was abandoned. Two different RNA substrate concentrations were used; in the higher concentration the activity was measured at pH 5.5 to 6 and 7.5, in the lower concentrations at pH 7. Protein measurement was performed after the method of LOWREY (LOWREY et al. 1951) as modified by GLASER and KLEINE (1962); blood sugar was determined in tail vein blood by means of o-toluidine technique. In the liver homogenate with ethyl alcohol the RNA extraction was modified according to the data given by OGUR and ROSEN (1950); RNA determination was done colorimetrically using orcin hydrochloric acid. For dry weight determination the same homogenate was used. Alloxan diabetes was induced by injecting the rats 175 mg/kg b.w. of alloxan after fasting for 24 hours. The 5% alloxan solution in citrate buffer (pH = 4) was prepared immediately before injection. For further experimentation only those animals with blood sugar values of greater than 300 mg/100 ml were employed...

Animals↗
PubMed1996

Modulation of human bronchial epithelial cell IIICS fibronectin mRNA in vitro.

Fibronectin (Fn) is an extracellular matrix glycoprotein which is involved in wound repair, including repair of injured airway epithelium. Bronchial epithelial cells (BECs) are known to produce Fn which has enhanced chemotactic activity compared to serum Fn. Alternative splicing of the Fn gene is an important mechanism by which cells regulate the production of Fn. Human BECs produce Fn which contains the EIIIA region, but the expression of IIICS region variants has not previously been reported. Our purpose was to better define the molecular characteristics of human BEC Fn by determining the expression of alternative splice variants of the IIICS region of Fn of human BECs in vitro. Human bronchial epithelial cells obtained from bronchoscopy were cultured. To examine the presence of IIICS messenger ribonucleic acid (mRNA) variants, we synthesized oligonucleotide primers complementary to the published human fibronectin complementary deoxyribonucleic acid (cDNA) sequence of the IIICS domain for use in polymerase chain reactions (PCR) with total ribonucleic acid (RNA) extracted from cultured human BECs. To examine the modulation of IIICS mRNA expression, the 428 base pair (bp) DNA fragment generated in the PCR was oligo-labelled with 32[P]-deoxycytidine triphosphate (dCTP) for use as a probe for Northern blot analysis. Human BECs were cultured in the presence and absence of transforming growth factor-beta (TGF-beta) and agents which influence cyclic adenosine monophosphate (cAMP) including isoproterenol and dibutryl cAMP (db-cAMP). Total RNA from cultures was extracted, electrophoresis performed, and Northern blots obtained. Blots were hybridized with IIICS probe, total Fn cDNA, and tubulin cDNA. It was found that human BECs in culture expressed the five known human IIICS variants. TGF-beta enhanced the expression of IIICS mRNA in a concentration- and time-dependent fashion. Isoproterenol and db-cAMP both reduced the expression of IIICS mRNA and attenuated the TGF-beta induction. Changes in IIICS mRNA paralleled changes in total Fn mRNA, suggesting that these agents do not selectively modulate only the IIICS domain of Fn. We conclude that human airway epithelial cell Fn in vitro does contain mRNA for five IIICS variants, and that IIICS mRNA can be modulated by TGF-beta and agents which influence cAMP. It is unknown whether alterations in IIICS variants contribute to the functional differences previously observed between airway epithelial cell Fn and plasma-derived Fn.

Base Sequence↗
PubMed2005

Quantitation of HIV-1 RNA in breast milk by real time PCR.

HIV-1 RNA in breast milk is a strong predictor of HIV-1 transmission through breastfeeding. In the present report, breast milk samples from HIV-1 uninfected donors were spiked with dilution of quantified culture supernatant from HIV-1(NDK) infected PBMC. Two RNA extraction techniques based on silica extraction, Nuclisens (BioMerieux) and Triazol (Qiagen), two techniques based on guanidine thiocynanate/chloroforme extraction, TRIzol (Life Technologie) and Amplicor HIV-1 Monitor (Roche Diagnostic Systems), and one technique based on electrostatic adsorption on iron oxide micro beads (Promega) were compared. HIV-1 RNA was quantitated by real time PCR (LTR gene) and Amplicor HIV-1 Monitor. Combining magnetic micro beads extraction and real time PCR quantitation allowed to correctly quantify breast milk HIV-1 RNA, with a difference between the expected and measured HIV-1 RNA levels always lower than 0.3 log copies/ml. The same combination was confirmed on 25 breast milk samples from HIV-1 infected women collected in Kwazulu-Natal, South Africa, by comparing measurements with those obtained by the Amplicor HIV-1 Monitor (r(2)=0.88). Nucleic acid extraction by magnetic micro beads followed by real time PCR is a reliable, sensitive, rapid and simple procedure to quantify HIV-1 RNA in breast milk and allows for PCR inhibitors found frequently in these samples.

Female↗
PubMed2000

Interferon-tau modulates phorbol ester-induced production of prostaglandin and expression of cyclooxygenase-2 and phospholipase-A(2) from bovine endometrial cells.

Antiluteolytic actions of bovine interferon-tau (bIFN-tau) require suppression of prostaglandin F(2 alpha) (PGF(2 alpha)) production. Our objective was to test whether bIFN-tau could block PGF(2 alpha) production and synthesis of phospholipase A(2) (PLA(2)) and cyclooxygenase-2 (COX-2) enzymes induced by a protein kinase C (PKC) stimulator (phorbol 12,13 dibutyrate; PDBu). Bovine endometrial epithelial (BEND) cells were treated with PDBu in the presence or absence of bIFN-tau. Medium samples were analyzed for concentrations of PGF(2 alpha), whole-cell extracts were analyzed for abundance of PLA(2) and COX-2 by immunoblotting, and RNA extracts were examined for steady-state levels of COX-2 mRNA by Northern blotting. The PDBu stimulated production of PGF(2 alpha) between 3 and 12 h, levels of COX-2 mRNA by 3 h and protein expression of COX-2 and PLA(2) by 6 and 12 h, respectively. Added concomitantly with PDBu, bIFN-tau suppressed PGF(2 alpha) production, steady-state levels of COX-2 mRNA, and expression of COX-2 and PLA(2) proteins. Added after a 3-h stimulation with PDBu alone, bIFN-tau suppressed PGF(2 alpha) production after 1 h. Bovine IFN-tau inhibited intracellular mechanisms responsible for PGF(2 alpha) production in BEND cells, and this could be through both cytosolic and nuclear actions.

Animals↗
PubMed1995

Partial characterization of the RNA from LPS-stimulated macrophages that induces the release of chemotactic cytokines by resident macrophages.

It is well established that exogenous RNA is incorporated into eukaryotic cells and is able to exert various biological responses. Little, however, is known about the effects of such RNA on macrophages. In this study, we demonstrate that RNA extracted from macrophages stimulated with Escherichia coli lipopolysaccharide (LPS), referred to as L-RNA, in contrast to RNA from non-stimulated macrophages (N-RNA), induces the release of a macrophage-derived neutrophil chemotactic factor (MNCF) and interleukin-8 (IL-8) from macrophage monolayers. The effect of L-RNA was dependent of the integrity of the polynucleotide chain and was not due to LPS contamination since its ability to induce MNCF and IL-8 release was strongly reduced by RNase but was not affected by DNase or polymyxin B. The poly A(+)L-RNA and poly A(-)L-RNA fractions were able to induce the release of MNCF and IL-8, indicating that the L-RNA could be acting at transcriptional and translational levels. The demonstration that actinomycin-D and cycloheximide inhibited the release of MNCF and IL-8 by L-RNA-stimulated macrophages confirms this assumption. Fractionation of the total L-RNA by centrifugation on a 5-20% sucrose gradient showed that the L-RNA which sediments in the 4-5S region of the gradient is the only fraction capable of inducing the release of MNCF from naive macrophages. We have previously shown that macrophage monolayers stimulated with interleukin-1 beta or LPS release a low molecular RNA which also sediments in the same 4-5S region. Taken together, these results support our proposal that resident macrophages, when activated by injurious stimuli, in addition to secreting cytokines, also release a low molecular weight (4-5S) RNA which may act on the surrounding macrophages to further stimulate the release of cytokines. This process would amplify the inflammatory response and would increase the mechanisms involved in the defense response or tissue injury.

Animals↗
PubMed1977

Togavirus RNA: reversible effect of urea on genomes and absence of subgenomic viral RNA in Kunjin virus-infected cells.

Electrophoretic analyses showed that no RNase-sensitive RNA smaller than the genome was specified by the flavivirus Kunjin in infected Vero cells during the period of maximum RNA and protein synthesis. In contrast, RNA extracted from Sindbis virus-infected cells under similar conditions included the expected 42S RNA (equivalent to the genome) and the smaller 26S (interjacent) RNA. Treatment of the genome of both togaviruses with 12 M urea produced a reversible (possibly conformational) change; measurement of the molecular weights of the treated RNAs by co-electrophoresis with fully denatured ribosomal RNA markers in SDS-polyacrylamide gels yielded a value of 2.1 X 10(6) if 8 M urea was incorporated in the gels and 4.2 X 10(6) if urea was omitted from the gels. These results indicate that flavivirus messenger RNA is represented solely by the intact genome of m.wt. 4.2 X 10(6).

Arboviruses↗
PubMed1984

Translation in vitro of hepatitis A virus RNA.

RNA extracted from highly purified hepatitis A virus (HAV) particles was translated in an RNA-dependent, cell-free reticulocyte lysate system, and the products were analyzed by SDS-polyacrylamide gel electrophoresis and compared with proteins translated from RNA of poliovirus. The efficiency of translation in vitro of HAV RNA was comparable to that of poliovirus RNA. Processing of the putative precursor molecules of HAV proteins, studied in pulse-chase experiments, was impaired when compared with that of poliovirus. By radioimmunoprecipitation it was shown that most proteins produced by translation in vitro were related immunologically to the viral structural proteins of the virion.

Animals↗
PubMed1975

Sequence complexity of heterogeneous nuclear RNA in sea urchin embryos.

The sequence complexity of heterogeneous nuclear RNA is sea urchin gastrulas was measured by RNA-driven hybridization reactions with nonrepetitive sea urchin DNA. 28.5% of the sequence complexity of the genome is represented in the nuclear RNA. This amounts to 1.74 X 10(8) nucleotides of diverse sequence, more than 10 times the nucleotide complexity of the polysomal messenger RNA extracted from sea urchin embryos at the same stage. The complex set of nuclear RNA sequences driving this hybridization reaction was shown to be the same as the rapidly labeled hnRNA, using pulse-labeled nuclear RNA as driver.

Animals↗
PubMed1976

Effect of Fv-1 gene product on synthesis of N-tropic and B-tropic murine leukemia viral RNA.

The production of virus and the synthesis of virus-specific RNA has been studied in Fv-1n/n (NIH/3T3, SIM) and Fv-1b/b (BALB/3T3, SIM-R) cell lines after infection with N- or B-tropic MuLV. It was found that virus production, measured by reverse transcriptase activity in the medium, was 70-100 fold lower in cells resistant at the Fv-1 locus than in permissive cells. The virus-specific RNA, detected by hybridization. In RNA excess with complementary DNA, was reduced by approximately 70-100 fold in cytoplasm of resistant cells compared to permissive cells. A reduction of the same magnitude was observed in the levels of virus-specific RNA extracted from nuclei of resistant cells. Our data therefore show that virus-specific RNA levels are reduced in cells nonpermissive at the Fv-1 locus, suggesting that restriction of the Fv-1 gene product occurs at the level of transcription of the viral genome or at a pre-integration step, or, alternatively, that the RNA transcripts are rapidly degraded after their synthesis.

Cell Line↗
PubMed2000

Ultrasensitive in-house reverse transcription-competitive PCR for quantitation of HIV-1 RNA in plasma.

An ultrasensitive version of an 'in-house' reverse transcription-competitive polymerase chain reaction assay described previously for quantitation of human immunodeficiency virus type 1 (HIV-1) RNA in plasma was developed. The increase in sensitivity from 400 to 50 HIV-1 RNA copies/ml was achieved by pelleting virus particles from 1.8 ml plasma by centrifugation prior to RNA extraction, modifying competitor DNA structure and amounts, and redesigning primers. Quantitation of HIV-1 RNA in 130 samples tested previously by the standard assay showed that the two procedures yield comparable results (mean absolute difference, 0.26+/-0.20 log) and that the ultrasensitive version detects HIV-1 RNA below the threshold of sensitivity of the standard method. The ultrasensitive 'in-house assay' and the reference QUANTIPLEX HIV-1 RNA 3.0 had the same sensitivity and gave equivalent results (mean absolute difference, 0.19+/-0.11 log), as shown by parallel blinded testing of 47 plasma samples. Titration experiments with reconstructed plasma samples allowed the determination of a dynamic range of 50-500000 HIV-1 RNA copies/ml for the 'in-house' system. The interassay coefficient of variation for samples nominally containing 200, 4000 and 80000 HIV-1 RNA copies/ml were 33.4, 22.9 and 38.2%, respectively. The performance, turnaround time, and cost-effectiveness of this system make it suitable for medium-scale clinical application.

Centrifugation↗
PubMed2002

Evidence for the involvement of the RNA-dependent protein kinase (PKR) in the induction of human cytotoxic T lymphocytes against a synthetic peptide of HIV-1 by regulatory RNA.

Exogenous RNA molecules can be incorporated into eukaryotic cells and can exert a variety of biological effects. We have previously showed that exogenous RNAs obtained from lymphoid organs of animals immunized with synthetic peptides of HIV-1 are able to induce cell-mediated immune responses. In this study, animals were immunized with a synthetic peptide (pol: 476-484) of HIV-1, referred to as p9, which is a cytotoxic T lymphocyte (CTL) epitope. The RNA extracted from the lymphoid organs of animals immunized with p9 was termed p9-RNA. We have demonstrated that p9-RNA is active in inducing human CTL. The p9-RNA was also able to activate the RNA-dependent protein kinase (PKR) of human lymphocytes. The polyA(+) p9-RNA was the fraction responsible for the activation of this protein kinase. We also found that p9-RNA activates the transcription factor nuclear kappa B (NF-kappaB) by inducing the degradation of its inhibitor I-kappaB. Thus, these findings suggest that p9-RNA may act as a regulatory RNA and that the induction of CTL activity by p9-RNA could be mediated by PKR through NF-kappaB activation. It is known that CTL activity plays an important role in host defense against HIV-1 infection. Elucidating the molecular mechanism of p9-RNA could contribute to determining the basis for the use of p9-RNA as an immunomodulator in HIV-infected patients.

Animals↗
PubMed1993

Expression of fibronectin messenger RNA in hypertrophic and normal dermal tissues and in vitro regulation by interferon alfa-2b.

After severe thermal injury, hypertrophic scarring which is associated with accumulation of extracellular matrix proteins including fibronectin, frequently develops. We have recently demonstrated that interferon alfa-2b significantly reduces the level of type 1 procollagen messenger RNA expressed by both hypertrophic and normal dermal fibroblasts. In this report, we provide evidence that this cytokine also significantly decreases the expression of fibronectin messenger RNA in human hypertrophic scar and normal dermal fibroblasts. Four dermal fibroblast cell strains were established in cell culture from four human postburn hypertrophic scar tissues with the use of normal dermal fibroblasts from the same patients as controls. These cells were then treated with 2000 U/ml interferon alfa-2b in culture medium at various times. The results of Northern analysis of interferon-treated dermal fibroblasts indicate that this cytokine reduced the expression of fibronectin messenger RNA as early as 12 hours after treatment and reached its lowest level (24% relative to untreated fibroblasts) after 96 hours. When the expression of fibronectin messenger RNA was quantified by densitometry for each individual paired cell strain, a differential response to interferon treatment was found among cell strains. The level of fibronectin messenger RNA expression decreased from 17.2% to 69% in hypertrophic scar fibroblasts and 47% to 83.7% in normal fibroblasts relative to that of untreated control values. Although this decrease was less pronounced in normal fibroblasts than in hypertrophic scar fibroblasts, this reduction was significant in both interferon alfa-2b treated hypertrophic scar fibroblasts (6.39 +/- 0.71 versus 2.88 +/- 0.9, n = 4, p < 0.05) and normal cells compared with untreated controls (5.47 +/- 0.89 versus 3.64 +/- 0.99, n = 4, p < 0.05) as assessed with Student's paired t test. Rehybridization of the RNA blot prepared from interferon alfa-2b treated and untreated hypertrophic scar fibroblasts with a complementary DNA for the tissue inhibitor of metalloproteinase type 2 gelatinase inhibitor showed no significant changes in abundance of this transcript. This result suggests that this cytokine selectively suppresses the expression of fibronectin messenger RNA and that this reduction is not due to RNA loading. A dot blot analysis of total RNA extracted from these tissues was carried out to compare the expression of fibronectin messenger RNA between human hypertrophic scar tissues and normal dermis obtained from the same patients. The blot was initially hybridized with fibronectin complementary DNA and subsequently with a complementary DNA for the tissue inhibitor of metalloproteinase type 2 to correct for RNA loading. When the ratio of fibronectin to tissue inhibitor or metalloproteinase type 2 messenger RNA expression for each hypertrophic scar tissue was compared with its normal control, this ratio was fourfold higher in human hypertrophic scar tissues relative to normal controls. In contrast, the expression of this message in cultured hypertrophic scar fibroblasts was not significantly different from that in normal fibroblasts. The results of this study suggest that hypertrophic scarring developing after thermal injury is associated with an overexpression of fibronectin messenger RNA, and interferon alfa-2b may be of therapeutic value to down-regulate the expression of this transcript.

Journal Article↗
PubMed1978

Age-dependent relaxation of gene repression: increase of endogenous murine leukemia virus-related and globin-related RNA in brain and liver of mice.

A progressive loss in the ability of cells to maintain their normal specialized states of differentiation could be the common denominator underlying much of the physiology and pathology associated with the mammalian aging process. We investigated this possibility by searching for an age-dependent derepression of endogenous genes in tissues in which they are not normally expected to be expressed. Complementary DNA (cDNA) probes to globin genes and to the murine leukemia type C RNA virus (MuLV) genome were used to detect the presence of RNA complementary to these genes in RNA extracted from brain and liver in young and old mice. Significant amounts of globin RNA were found in brain nuclei and cytoplasm. No age difference was found in the globin RNA sequences present, but the number of globin RNA molecules increased from about 15 in 6-month to 34 in 27-month-old animals for nuclei and 280 in 6-month to 500 in 27-month-old animals for cytoplasm. Similar results were found for liver. RNA complementary to the MuLV cDNA probe was also found but, in contrast to globin, the different RNA sequences increased in both brain and liver nuclei from about 45% of the MuLV genome in 6-month to 72% in 27-month-old animals. The number of MuLV-related RNA molecules remained constant at about 22 and 38 per nuclei for brain and liver, respectively. Derepression of genes of this magnitude could result in a time-dependent increase in virus-related diseases and a general deterioration of the organism.

Aging↗
PubMed1991

Modulation of expression of virus-like elements following exposure of mice to high- and low-LET radiations.

Modulation of virus expression has been reported following exposure to a variety of cellular stresses, including UV radiation and heat-shock. The experiments reported here were designed to examine expression of endogenous VL30 (virus-like 30 S) elements following exposure of whole mice to ionizing radiations. Whole mice were exposed to doses of neutrons (50 cGy) or gamma-rays (300 cGy) shown to be equally efficient in cancer production in the whole animal, and tissues were harvested at 10 and 60 min following completion of the exposure. RNA extracted from these tissues and from tissues of untreated controls was examined for VL30 RNA accumulation by dilution dot blot and Northern blot analyses. These studies revealed that neutrons repressed VL30 RNA accumulation evident within 10 min following exposure in brain, gut, thymus and spleen but not in liver, in which VL30 RNA was unaffected by radiation exposure. During this same time interval, gamma-rays induced VL30 expression in gut and brain and to a lesser extent in liver. These experiments suggest the presence of a differential molecular response following whole-body exposure to high- versus low-LET radiations. In addition, this work demonstrates that ionizing radiations may affect expression of murine endogenous viral sequences.

Animals↗
PubMed2006

Medically assisted procreation and transmission of hepatitis C virus: absence of HCV RNA in purified sperm fraction in HIV co-infected patients.

OBJECTIVE: The risk of hepatitis C virus (HCV) transmission in medically assisted procreation (MAP) is debated and some researchers have proposed to exclude MAP for HCV-positive infertile patients. The objectives of this study were to assess the presence of viral RNA in the final preparation of density gradient semen fractions collected from men with chronic HCV and HIV co-infection participating in a MAP program, and to assess whether HIV co-infection influences the rate of the presence of HCV RNA in the semen. DESIGN AND METHODS: The study was based on a cohort of 170 HCV-infected male patients (93 HIV co-infected) participating in a MAP program in a French center. Semen samples were subjected to standard MAP sperm preparation, using density-gradient centrifugation with 40 and 90% layers. All aliquots were tested with a commercially available HCV RNA assay (Roche Monitor), adapted for use with semen after a nucleic HCV RNA extraction modification (Organon Technika). RESULTS: Seminal plasma samples from 19 (11%) patients were HCV RNA positive. The positive HCV viral load in semen was less than 600 IU/ml. None of the 90% fractions from HCV-infected patients were HCV RNA positive. Among the 93 co-infected patients, 10 were positive for HCV RNA in semen and three were HIV/HCV RNA positive in semen. CONCLUSIONS: Although HCV RNA was found in the semen of 11% of patients, no purified sperm fraction, or spermatozoa used in MAP were HCV RNA positive. The 90% purified sperm fraction discards the virus and must be used with care in MAP.

Adult↗
PubMed1987

Acclimation of Ribulose Bisphosphate Carboxylase and mRNAs to Changing Irradiance in Adult Tobacco Leaves: Differential Expression in LSU And SSU mRNA.

The transfer of Nicotiana tabacum plants grown in low light (60 micromoles quanta per square meter per second) to higher light (360 micromoles quanta per square meter per second) was previously shown to induce adaptive stimulation of photosynthetic capacities. The variations of ribulose bisphosphate carboxylase/oxygenase (RubisCo) expression in mature leaves was examined as a result of this acclimation. Maximum or initial activities increased markedly after low- to high-light transfer with a maximum effect after 2 to 3 days. The higher activity is mainly explained by RubisCo protein synthesis as shown by immunorocket technique. Small subunits of RubisCo (SSU) mRNA relative content determined by hybridization of total RNA with DNA probe by Dot-blot method, followed the same pattern as RubisCo quantity. The magnitude of this response was amplified when more contrasting light conditions (25 versus 360 micromoles per square meter per second) were established on the same leaf: RubisCo activity, RubisCo protein, and SSU mRNA contents decreased in the shaded zone and increased in the high-light zone within 1 day. After 2 days the shade/light ratio was 1 to 3 for RubisCo protein and 1 to 4 for SSU-RNA, whereas the ratios remained equal to one in controls. Hybridization of the same RNA extracts with large subunits of RubisCo (LSU) probe showed no variation in LSU-RNA content. So in green adult leaves, the expression of SSU and LSU genes is regulated differently. The observed white light quantitative effect on RubisCo expression was not dependent on the photosynthetic rate or assimilate content since low CO(2) concentration around the leaf after the light shift did not modify the response.

Journal Article↗
PubMed1991

Induction of granulocyte and granulocyte-macrophage colony-stimulating factors from human monocytes stimulated by Fc fragments of human IgG.

The effect of human IgG on human haemopoiesis has been studied in vitro. Dialysed purified IgG stimulated haemopoietic colony growth by bone marrow mononuclear cells (MNC) but not by monocyte-depleted MNC. Culture media, conditioned by IgG-stimulated peripheral blood MNC, augmented formation of neutrophil-macrophage, eosinophil, and megakaryocyte colonies by monocyte-depleted marrow MNC. Serum-free IgG-conditioned media also contained colony-stimulating activity (CSA). IgG Fc fragments and heat-aggregated IgG promoted the secretion of CSA, but F(ab')2 fragments, Fab fragments or ultracentrifuged IgG did not. In the cell-selection studies, CSA was produced by highly enriched monocytes following stimulation with Fc fragments. The antiserum against human granulocyte colony-stimulating factor (G-CSF) and/or granulocyte-macrophage CSF (GM-CSF) neutralized the CSA produced by Fc fragment-activated monocytes. Enzyme immunoassays showed G-CSF and GM-CSF in media conditioned by monocytes stimulated with the Fc fragments, heat-aggregated IgG and anti-D-sensitized red blood cells (RBC). Northern hybridization analysis showed mRNA encoding G-CSF and GM-CSF in RNA extracted from MNC and monocytes cultured with the Fc fragments, but not in the RNA from unstimulated cells or monocyte-depleted MNC. These results indicate that IgG Fc fragments, aggregated IgG and antigen-antibody complexes induce monocytes to produce G-CSF and GM-CSF in vitro. The CSFs release induced by IgG may be involved in the in vivo regulatory network in haemopoiesis.

Cell Division↗
PubMed2002

Desulfovibrio sp. genes involved in the respiration of sulfate during metabolism of hydrogen and lactate.

To develop a better understanding of respiration by sulfate-reducing bacteria, we examined transcriptional control of respiratory genes during growth with lactate or hydrogen as an electron donor. RNA extracts of Desulfovibrio desulfuricans subsp. aestuarii were analyzed by using random arbitrarily primed PCR. RNA was reverse transcribed under low-stringency conditions with a set of random primers, and candidate cDNAs were cloned, sequenced, and characterized by BLAST analysis. Putative differentially expressed transcripts were confirmed by Northern blot analysis. Interestingly, dissimilatory bisulfite reductase was upregulated in the presence of hydrogen. To link these transcriptional changes to the physiology of sulfate-reducing bacteria, sulfide was measured during growth of several strains of Desulfovibrio on hydrogen or lactate, and this revealed that hydrogen-grown cells produced more sulfide per unit of cell mass than lactate-grown cells. Transcription of other redox proteins was characterized by Northern blotting to determine whether or not they were also transcribed to higher levels in hydrogen-grown cells. Growth on lactate produced greater transcription of [NiFe] hydrogenase. H(2)-grown cells transcribed the adenylylsulfate reductase b subunit and HmcA to higher levels. The results we describe here provide new insight into the continuing debate over how Desulfovibrio species utilize redox components to generate membrane potential and to channel electrons to sulfate, the final electron acceptor.

Bacterial Proteins↗