PubMed Health⌕ Search

Biomedical subjects

M R Morrison

Publications and source records attributed to M R Morrison.

At least 37 records · Page 2Linked to original sources
PubMed1982

Normalization of cerebellar RNA synthesis and mRNA levels after treatment of graft versus host disease.

We have previously shown that neonatal rats with graft versus host disease (GVHD) (1) synthesize significantly less cerebellar RNA, (2) have RNA that is less translationally active, and (3) have changes in the relative abundance of certain mRNAs, including the induction of one coding for protein r that is present neither in control cerebellum nor in other brain regions at any age. Here we report on the ability of the cerebellum to recover from GVHD-induced changes in the synthesis of total RNA and in the relative levels of specific mRNAs. In order to halt the disease, 11-day-old diseased Fischer animals were injected with hyperimmune alloantiserum daily for 3 days. Cytoplasmic RNAs were isolated from the cerebella of 14-day-old serum-treated animals, their diseased littermates that were not treated with serum, and littermate controls. Comparison, by two-dimensional gel analysis, of the in vitro synthesized mRNA translation products showed that most GVHD-induced alterations in the levels of specific mRNAs were not present in serum-treated animals. In particular, protein r was not synthesized by cerebellar RNAs isolated from serum-treated animals. These results show that the adverse effects of this disease are reversible at the molecular level.

Animals↗
PubMed1980

Relative increase in polysomal mRNA for R1 cAMP-binding protein in neuroblastoma cells treated with 1,N6-dibutyryl-adenosine 3',-5'-phosphate.

Polysomal RNAs were isolated from control neuroblastoma cells and those treated with 1,N6-dibutyrl-adenosine 3',5'-phosphate (Bt2cAMP) and translated in wheat germ lysates. Comparison of proteins synthesized in vitro on two-dimensional gel electrophoretograms showed that there was a specific induction in the synthesis of a protein, Mr 48000, by the polysomal RNAs from Bt2cAMP-treated cells. This protein was identified as the R1 cAMP-binding protein by its coelectrophoresis with unlabelled binding protein and by its specific retention on 8-(6-aminohexylamino)-adenosine 3',5'-phosphate linked to Sepharose. Quantification of the proteins synthesized in vitro with subsaturating inputs of polysomal RNAs showed that there was a 1.4--1.7-fold increase in the synthesis of the R1 cAMP-binding protein by polysomal RNAs isolated from Bt2cAMP-treated cells. There was a similar increase when purified polyadenylated mRNA populations were compared. showing there was no change in the ratio of adenylated to nonadenylated mRNAs in the induced mRNA population. There was no corresponding increase in the synthesis of the R2 cAMP-binding protein although the relative synthesis of several other proteins was also increased and the synthesis of actin and the alpha and beta-tubulin subunits was decreased. The increased levels of the R1 cAMP-binding protein found in Bt2cAMP-treated neuroblastoma cells are therefore partly caused by a specific accumulation of its mRNA on polysomes. The mRNA content of the cytoplasmic messenger ribonucleoprotein (mRNP) population of control cells was insufficient to account for this increase by a translocation of R1 mRNA from the mRNP to the polysome fraction in Bt2cAMP-treated cells. The increase in polysomal R1 mRNA is therefore caused by its increased transcription of post-transcriptional processing or its decreased rate of degradation in Bt2cAMP-treated cells. Although the R1 and R2 binding proteins have identical molecular weights and similar pI values, the specific induction of the mRNA for R1 cAMP-binding protein and the differential distribution of the R1 and R2 mRNAs between the polysomal and messenger ribonucleoprotein compartments show that these two cAMP-binding proteins are encoded by different mRNA populations.

Animals↗
PubMed1980

Changes in RNA synthesis and messenger RNA content in the cerebellum of rats with graft versus host disease.

Cerebellar RNA accumulation, synthesis, and functional capacity was studied in 14-day-old F1 hybrid rats subjected to neonatally induced graft versus host disease (GVHD). There was a decrease in RNA synthetic rate as measured by the uptake of labeled precursors into RNA. The decrease in total cerebellar RNA synthesis was reflected both in a reduced amount of Nissl substance, visible in cresyl violet-stained 10-micron-thick sections of cerebella, and in the total amount of cytoplasmic RNA isolated from individual cerebella from diseased animals compared with control littermates. Analysis of the RNA translational capacity in wheat germ protein synthesizing systems showed that RNA from experimental animals was also biologically less active. Qualitative differences between protein populations in control and diseased animals were analyzed by two-dimensional gel electrophoresis. There were few alterations in the steady state levels of cerebellar protein. However, two-dimensional gel electrophoresis of the peptides synthesized in vitro by RNA from control and diseased animals showed that there were several changes in the relative abundance of some mRNAs between the two RNA populations. These data show that the cerebellar RNA from rats with GVHD differs both qualitatively and quantitatively from that of controls.

Animals↗
PubMed1977

Quantitation and characterisation of poly(A)-containing messenger RNAs from mouse neuroblastoma cells.

Comparison of several isolation procedures for neuroblastoma poly(A)-containing mRNAs shows that the highest percentage recovery of undegraded and biologically active messenger RNAs is obtained using proteinase K prior to phenol extraction. The messenger RNAs thus isolated comprise approximately 1.5% of the total ribosomal RNAs and have negligible contamination with 18 and 28 S RNAs. On denaturing polyacrylamide gels they have an average molecular weight of 6.5-10(5) with a range from 2.2-10(5) to 1.53-10(6). The messenger RNAs have an average poly(A) content of 154 nucleotides. They are highly active in wheat germ in vitro protein synthesizing systems, giving as much as 4.3 pmol [35S]methionine incorporation into total protein per mol of mRNA. This is almost as active as a control globin mRNA preparation.

Animals↗
PubMed1976

Molecular weight determinations on the alpha-globin and beta-globin mRNAs.

The globin mRNAs containing between 30 and 40 polyadenylate residues can be separated from thos mRNAs containing longer poly(A) regions by Millipore filter binding. The molecular weights of the alpha-and beta-globin mRNAs containing this size class of poly(A) have beed determined by lectrophoresis on 3.7% polyacrylamide gels in the presence of 99% formamide. Because the number of adenylic acid residues in these mRNAs is known, the number of non-poly(A) nucleotides can be accurately calculated. The molecular weight of the beta-globin mRNA is 235 000 +/- 28 000 (736 +/- 88 nucleotides) and that of the alpha-globin mRNA is 208 900 +/- 43 870 (653 +/- 78 nucleotides). By subtracting the number of nucleotides in the coding and poly(A) regions, the number of non-coding nucleotides in the beta-globin mRNA were calculated to be 261, 69 more than the 193 present in the alpha-globin mRNA. Comparison of size estimates of newly synthesized globin mRNAs containing longer average lengths of poly(A) shhowed that there is no comparable processin of the 5' termini of the alpha-and beta-globin mRNAs concomitant with the stepwise degradation of the poly(A) regions which occur as the mRNAs mature.

Animals↗
PubMed1975

Characterization of globin messenger ribonucleic acids in membrane polysomes of mouse reticulocytes.

Between 20 and 30% of the polysomes in mouse reticulocytes are associated with the cell membrane fraction. These polysomes are not liberated by washing with 0.5 m KCl and are therefore thought to be attached to membranes. They have the same percentage of polyadenylic acid-containing RNA, as determined by oligo(dT)-cellulose affinity chromatography, as cytoplasmic polysomes. Analysis of the RNA by polyacrylamide gel electrophoresis in aqueous solutions shows that at least 95% of the RNA migrates identically with the cytoplasmic polysomal globin mRNAs. Electrophoresis in 99% formamide resolves the membrane mRNAs into two bands which migrate identically with the cytoplasmic alpha- and beta-globin mRNAs. The molar ratio of the alpha- and beta-globin mRNAs, as determined by quantitating the bands on the formamide gels, is similar to that of the cytoplasmic mRNAs. There is also no difference in biological activity between the two messenger preparations. The polyadenylic acid in the membrane mRNAs, isolated after labeling mice in vivo for 20 hours with (32P)orthophosphate, migrates with the three broad size classes previously shown to be present in the cytoplasmic globin mRNAs. The 32P specific activity of the membrane mRNAs and ribosomal RNA fractions after different times of labeling with 32Pi are similar to those from cytoplasmic polysomes. These observations show that the reticulocyte membranes contain approximately 20% of the cellular globin nRNAs, and that these mRNAs are similar to those from cytoplasmic polysomes.

Animals↗