Evidence against a mitochondrial location of the 7-2/MRP RNA in mammalian cells.
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Centrifugation, Density Gradient↗
Biomedical subjects
T Kiss
Publications and source records attributed to T Kiss.
Cap structure of U3 small nucleolar RNA in animal and plant cells is different. gamma-Monomethyl phosphate cap structure in plant RNA.
U3 small nucleolar RNA (snoRNA) is an abundant small RNA involved in the processing of pre-ribosomal RNA of eukaryotic cells. U3 snoRNA has been previously characterized from several sources, including human, rat, mouse, frog, fruit fly, dinoflagellates, slime mold, and yeast; in all these organisms, U3 snoRNA contains trimethylguanosine cap structure. In all instances where investigated, the trimethylguanosine-capped snRNAs including U3 snoRNA, are synthesized by RNA polymerase II. However, in higher plants, the U3 snoRNA is synthesized by RNA polymerase III and contains a cap structure different from trimethylguanosine (Kiss, T., and Solymosy, F. (1990) Nucleic Acids Res. 18, 1941-1949; Marshallsay, C., Kiss, T., and Filipowicz, W. (1990) Nucleic Acids Res. 18, 3451-3458; Kiss, T., Marshallsay, C., and Filipowicz, W. (1991) Cell 65, 517-526). In this study, we present evidence that cowpea and, most likely, tomato plant U3 snoRNA contains a methyl-pppA cap structure. These data show that the same U3 snoRNA contains different cap structures in different species and suggest that the kind of cap structure that an uridylic acid-rich small nuclear RNA contains is dependent on the RNA polymerase responsible for its synthesis. In vitro synthesized plant U3 snoRNA, with pppA or pppG as its 5' end, was converted to methyl-pppA/G cap structure in vitro when incubated with extracts prepared from wheat germ or HeLa cells. These data show that the capping machinery is conserved in organisms as evolutionarily distant as plants and mammals. Nucleotides 1-45 of tomato U3 snoRNA, which are capable of forming a stem-loop structure, are sufficient to direct the methyl cap formation in vitro.
Animals↗
[Actinomycosis with abdominal manifestation].
During the last 4 years the authors observed 3 actinomycotic cases with abdominal localization. The disease was found in all the three cases to be localized to those parts of the intestinal tract where stasis of fecal contents may occur, i. e. to the appendix, to Meckel's diverticle and to the left colonic flexure. The relatively rare incidence and preoperative diagnostic difficulties make publication of these cases worthwhile. Based on own experience and literary data they describe natural history, clinical picture, histology and treatment of the disease, respectively.
Actinomycosis↗
[Laparoscopic appendectomy].
We have performed the first laparoscopic appendectomy in Hungary. Laparoscopic appendectomy is a new, minimally invasive method in abdominal surgery. We consider it a worthwhile alternative to classical appendectomy.
Adolescent↗
7-2/MRP RNAs in plant and mammalian cells: association with higher order structures in the nucleolus.
Mammalian MRP (for mitochondrial RNA processing) RNA, also known as 7-2 RNA, is a nuclear encoded small RNA which has been reported to function in two different cellular compartments: in the mitochondria and in the nucleus. The ribonucleoprotein particle which contains the 7-2/MRP RNA, called RNase MRP, has ribonucleolytic activity and shares some structural similarity with RNase P. It has been proposed that in mitochondria, the RNase MRP is responsible for endonucleolytic cleavage of primer RNA during DNA replication. We have characterized the gene and cDNAs encoding 7-2/MRP-like RNA in Arabidopsis and tobacco, and found that in plants this RNA is enriched in nucleoli but is undetectable in purified mitochondria isolated from tobacco leaves or cells grown in suspension. In glycerol gradients tobacco 7-2/MRP RNA cosediments with large approximately 80S structures possibly representing ribosomal precursors. Fractionation of HeLa cells has also revealed that 7-2/MRP resides in the nucleolus and that most of it is associated with complexes sedimenting at approximately 80S, similar to those containing the U3 nucleolar RNA which is known to participate in pre-rRNA processing. These results indicate that the 7-2/MRP ribonucleoparticle may be involved in ribosome biogenesis, in both plant and mammalian cells.
Animals↗
Lead ions close steady-state sodium channels in Helix neurons.
Extracellularly applied Pb2+ (1-150 microM) induced an outward current (IPb) in intracellularly perfused snail neurons. The current-voltage relationship of the Pb(2+)-induced current was linear over the potential range of -100 to -40 mV with negative slope conductance. The Pb-induced current was strongly dependent on the Na+ gradient. The IPb in intra- or extracellular K+- and Cl(-)-free or -rich solutions was almost the same as in control external and internal salines. The negative slope of the I-V curve and the decreased conductivity during Pb2+ application suggested that IPb is owing to the blocking of the resting Na conductance. Data obtained from single-channel measurements also supported this conclusion. Patch-clamp data showed that the steady-state Na channel has a conductance of 14 pS and both closed and open time-distributions displayed single exponential character.
Animals↗
[Data on possibilities of rehabilitation of lower limb amputees].
The authors investigated ways to improve the results of rehabilitation during the course of their clinical practice. During the last 2 years, amputation was performed on 136 patients and 50 patients were supplied with temporary protheses. 38 patients out of 50 answered the question form supplied. After analysis of the question form, the authors summarized the possibilities to improve the results of prolonged mobilisation and rehabilitation. This programme stresses the need for 1. early mobilisation-teaching to walk and 2. care of body and soul.
Amputees↗
Alteration of the RNA polymerase specificity of U3 snRNA genes during evolution and in vitro.
We present evidence that the genes encoding U3 snRNA in plants are transcribed by RNA polymerase III (pol III) and not by RNA polymerase II (pol II) as in vertebrates or lower eukaryotes. The U3 gene is the only known example of a gene transcribed by different polymerases in different organisms. It is possible to convert the plant U3 gene into a functional pol II-transcribed gene by manipulating the spacing between the promoter elements and inserting a pol II-specific termination signal. Pol II-transcribed U3 RNA, containing the 5'-terminal cap different from that present in the wild-type counterpart, is packaged in transfected protoplasts into U3 snRNP precipitable with anti-fibrillarin antibodies. These findings provide further evidence for the common ancestry of the pol II and pol III transcription systems, and indicate that promoter diversification in some genes has occurred relatively recently.
Base Sequence↗
Copper-induced non-selective permeability changes in intracellularly perfused snail neurons.
The effect of extracellularly applied Cu2+ was studied on isolated intracellularly perfused Helix pomatia neurons. It was found that the Cu(2+)-activated current (ICu) is biphasic and composed of overlapping outward and inward components. The outward component of ICu is the result of a blockade by Cu2+ of the steady-state outward Cl- current. The inward component is assumed to flow through Ca(2+)-activated non-selective cationic channels. The washing-out procedure resulted in a large inward current (Iw), which was composed of transient and steady-state components. It is most likely that the activation of metabolic pumps is responsible for the transient component and the steady-state component is the result of increased neuronal membrane permeability for Cl-. Moreover, both ICu and Iw were highly Ca(2+)- and temperature-dependent processes. It is concluded that Cu2+ application resulted in complex permeability changes in the Helix pomatia neurons.
Animals↗
Coordination of copper(II) ions to catechoyl-dipeptides, the inhibitors of leucine aminopeptidase and ribonucleotide reductase.
Potentiometric and spectroscopic study of the coordination ability of 2,3- and 3,4-dihydroxybenzoyl-dipeptides has shown that catechoyl-dipeptides are very strongly-binding ligands. The coordination begins at the catechol site at pH below 4. In the case of 2,3-dihydroxy derivatives the peptide unit may also be involved in the copper(II) ion coordination via its peptide nitrogens. The biological tests have indicated that the studies ligands may be effective inhibitors of ribonucleotide reductase in some cases, with a reasonable level of selectivity.
Animals↗
Effect of Ag+ on membrane permeability of perfused Helix pomatia neurons.
1. Isolated, non-identified neurons were voltage clamped using the internal perfusion technique. 2. Ions of Ag+ (1-100 microM) introduced into the bathing solution activated a steady-state inward current (IAg) in the soma. The effect of Ag+ was reversible when the concentration of Ag+ was less than 75 microM or the time of application was shorter than 10 min. 3. IAg was observed both in the presence and absence of Na+ ions in the extracellular saline. It could also be activated when Cs+ ions were substituted for Na+ ions. 4. The current-voltage characteristics were linear in the voltage range -100 to 0 mV. The reversal potential in control saline was an average of 1.19 +/- 5.1 mV. 5. The application of Ag+ ions induces an elevation of intracellular free Ca2+ concentration by 10-20 times in both Ca(2+)-containing and Ca(2+)-free extracellular salines, as revealed by Fura-2 measurements. 6. Agents that increase the intracellular free Ca2+ concentration ([Ca2+]i), like thymol, caffeine and dinitrophenol, increased the amplitude of IAg. The effect was additive. Ruthenium Red, which blocks the release of Ca2+ from intracellular stores, decreased the Ag+ effect. 7. It is concluded that extracellularly applied Ag+ ions increase the cytoplasmic free Ca2+ concentration, which in turn activates non-specific cationic channels. 8. Ag+ ions in 1-10 microM concentration were able to decrease the voltage-activated Ca2+ current amplitude. This decrease, however, was due to the increase of [Ca2+]i which caused Ca(2+)-dependent inactivation.
Animals↗
Neurohypophysial peptides selectively depressed high voltage-activated Ca-current in snail neurons.
It was found that neurohypophysial peptides oxytocin and Lys-vasopressin selectively decreased the high voltage-activated component of the inward Ca-current in voltage-clamped Helix pomatia identified neurons in a dose- and time-dependent manner. This effect was unaffected or further enhanced applying phosphodiesterases inhibitors. It is suggested that suppression of high voltage-activated current was due to the activation of the adenylate cyclase system, likely protein kinase A.
Animals↗
[Early results of balloon catheter dilatation in ilio-femoral-popliteal arterial occlusion].
Since 1981 intraoperative balloon dilatation has been performed in 78 patients suffering from occlusive arterial disease of the lower extremities. In 34 patients the proximal iliac stenosis was dilated (common iliac artery: 15 and external iliac artery: 27) in association with a femoro-popliteal reconstruction. In 44 patients, the femoro-popliteal segment distal to an ilio-femoral reconstruction was dilated. In the early postoperative period (0-30 days) there was no reocclusion in the group of proximal dilation. In the other group, where the out-flow tract was dilated, in one case femoral amputation, while in another patient reoperation was necessary because of early reocclusion. The combining intraoperative balloon dilatation with surgical reconstruction may decrease the risk, and simplify the management of patients with multiple vascular lesions and it is valuable adjunct to vascular surgery to improve inflow or outflow.
Adult↗
Nucleotide sequence and expression of a new Arabidopsis U2 snRNA gene.
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Base Sequence↗
Amplification of plant U3 and U6 snRNA gene sequences using primers specific for an upstream promoter element and conserved intragenic regions.
U-snRNA genes in higher plants contain two essential promoter elements, the USE with sequence RTCCCACATCG and the TATA-like box, positioned in the -70 and -30 regions, respectively. Using an oligodeoxynucleotide containing the USE motif and oligodeoxynucleotides specific for the intragenic regions conserved in U-snRNAs, several sequences encoding U6 and U3 snRNAs were determined by polymerase chain reaction (PCR) amplification of Arabidopsis thaliana and tobacco genomic DNAs. This method provides a simple and rapid procedure for characterisation of plant U-snRNA genes and their promoters. It could also be used for the characterisation of other genes containing conserved upstream promoter elements. PCR-derived fragments were used as probes for the isolation of the U3 snRNA genes from a genomic library of Arabidopsis. Two isolated U3 genes were shown to be active when transfected into protoplasts of Nicotiana plumbaginifolia. Both U3 genes contain the USE and TATA-like upstream elements located in similar positions to the U6 genes of Arabidopsis. The encoded Arabidopsis U3 snRNAs can be folded into a secondary structure which is more similar to that of U3 RNAs from lower eukaryotes rather than from metazoa.
Base Sequence↗
Molecular analysis of a U3 RNA gene locus in tomato: transcription signals, the coding region, expression in transgenic tobacco plants and tandemly repeated pseudogenes.
By screening a tomato genomic library with a tomato U3 RNA probe, we detected a U3 genomic locus whose coding region was determined by primer extension (5' end) and direct RNA sequencing of purified U3 RNA from tomato (3' end). Tomato U3 RNA is 216 nucleotides long, contains all the four evolutionarily highly conserved sequence blocks (Boxes A to D), has at its 5' end a cap not precipitable with anti-m3G antibodies and can be folded into a peculiar secondary structure with two stem-loops at its 5' end. A tagged derivative of the U3 gene was faithfully expressed in transgenic tobacco plants. In the 5' flanking region both plant-specific UsnRNA transcription signals [the TATA-like sequence and the upstream sequence element (USE)] were present, but were positioned closer to each other and also to the cap site in the U3 gene than in the genes for the plant spliceosomal UsnRNAs studied so far. The 3' flanking region of the tomato U3 gene lacked the consensus sequence of the putative termination signal established for the plant spliceosomal UsnRNA genes and contained a pyrimidine-rich tract (R1) followed by four tandemly repeated U3 pseudogenes (U3.1 ps to U3.4 ps) flanked by slightly altered forms (R2 to R5) of R1 and most probably generated by DNA-mediated events. Our results are in line with the conjecture that the enzyme transcribing the tomato U3 gene has different structural requirements for transcriptional activity than the enzyme transcribing plant U1, U2 and U5 genes.
Base Sequence↗
The 5' end of the coding region of a U6 RNA gene candidate from tomato starts with GUCC, a phylogenetically highly conserved 5' end sequence of U6 RNA.
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Base Sequence↗
[The role of autotransfusion in vascular surgery].
Use of autotransfusion has recently come into the limelight of clinical practice especially because of the AIDS-risk and financial considerations. Authors have analysed data of 20 patients with peripheral arterial disease at whom hemodilution were carried out before the operation with the aim of using autotransfusion. Attention is called to the importance of autotransfusion and its applicability in the practice of other sorts of surgery.
Acquired Immunodeficiency Syndrome↗