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A Felsani

Publications and source records attributed to A Felsani.

At least 37 records · Page 2Linked to original sources
PubMed1986

Sites hypersensitive to, and protected from, nuclease digestion in the regulatory region of wild-type and mutant polyoma chromatin.

It has been shown that the untranscribed regulatory region of polyoma virus (Py) is hypersensitive (Hs) to DNase I treatment, and that this hypersensitivity is located in two areas which correspond to the A and B domains of the enhancer. We mapped the DNase I hypersensitive sites in the Py regulatory region of wild-type (PyA2) and of mutants, selected in neuroblastoma cells (PyNB), which are characterized by an extensive duplication involving the A domain, with or without deletion of the B domain. The experiments were performed in both a permissive host (3T6 mouse fibroblasts) and in a restrictive host (41A3 mouse neuroblasts). No significant differences were observed between the two hosts. Our results show that four sites, in addition to the ones already described, can be identified in the wild-type A2 strain. These newly identified sites coincide with the domains of the enhancer region as they have recently been established. In PyNB mutants duplications and deletions are generally correlated to the gain or loss of the corresponding hypersensitive sites. However, a new site is formed in one of the duplicated sequences, even if no corresponding hypersensitive site is present in the other identical sequence. A region protected from DNase I digestion occurs in the PyNB mutants which corresponds to the junction of the duplication which is absent in the wild-type strain. In this region, as a consequence of the rearrangement, a GGCGGG motif which is very similar to the one (GGGCGG) present at the binding sites of the cellular regulatory protein SP1, is found.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Cloning and characterization of the ribosomal genes of the sea-urchin Paracentrotus lividus. Heterogeneity of the multigene family.

A Paracentrotus lividus genomic library was constructed using sperm DNA prepared from a single animal. The DNA was fragmented by partial digestion with DNase II, sized on a preparative agarose gel and inserted in the Pst I site of pBR 322 by the dG X dC tailing method. Recombinant plasmids containing ribosomal DNA were isolated, a restriction map of the gene was determined and the 18S and 26S transcribed sequences were located by S1 protection mapping. The organization of the ribosomal genes in genomic DNA of individual animals and of a pool of animals was studied by blot-hybridization of the restriction fragments, using as probes nick-translated 32P-labelled cloned ribosomal DNA fragments or 18S and 26S sea-urchin ribosomal RNA. The repeat length of the ribosomal unit was about 10.5 X 10(3) bases. A comparison of the restriction patterns of DNA from different animals showed a marked sequence heterogeneity in the spacer region of these genes. Variations of about 200 base pairs were detectable in the length of the spacer of some individuals.

Animals↗
PubMed1982

Expression in male and genomic organization of the gene(s) coding for a major protein secreted by the rat seminal vesicle epithelium.

Double strand cDNA copies of lls poly(A)+mRNA purified from adult rat seminal vesicles (RSV), have been cloned in E.coli C600 using the Pst I site of pBR322. Filter hybridization, nucleotide sequence analysis and positive hybridization translation were used to demonstrate that one of the recombinant plasmids obtained (pRSV25) contained a 260 bp long insert coding for a significant part of the precursor to the protein IV present in the RSV secretion. By using labelled pRSV25 DNA we have found that high levels of RSV IV mRNA were present only in the rat seminal vesicle epithelium. The amounts of RSV IV mRNA present in other tissues of the same organism were below the levels detectable by the methods used. In addition, other data reported here indicate that the RSV IV gene(s) is present in both sexes, probably with a different organization.

Animals↗
PubMed1980

Neural control of gene expression in the skeletal muscle fibre: the nature of the lesion in the muscular protein-synthesizing machinery following denervation.

Experiments are reported showing that following 8 days of denervation the function of the protein-synthesizing machinery, operating in the rat gastrocnemius fibres, is altered, probably as a consequence of decreased amounts of ribosomes and actively translated mRNA. In addition, the data obtained show that the amount per muscle and the availability per ribosome of the soluble factors involved in the process of protein synthesis are markedly decreased, thus suggesting that the amounts of ribosomes, mRNA and soluble factors are regulated in a concerted fashion when muscular protein synthesis is decreased after denervation.

Animals↗
PubMed1980

Neural control of gene expression in the skeletal muscle fibre: changes in the muscular mRNA population following denervation.

The mRNA populations of control and 8-days-denervated adult rat gastrocnemius have been analysed by the translation assay and the cDNA-mRNA molecular hybridization technique. This analysis demonstrates the appearance of marked changes in many of the mRNA sequences present in muscle fibres following denervation and thus gives strong support to the hypothesis that the motoneurons are able to control the gene expression of muscle fibres.

Animals↗
PubMed1980

Physicochemical characterization of the ribosomal RNA species of the Mollusca. Molecular weight, integrity and secondary-structure features of the RNA of the large and small ribosomal subunits.

1. The rRNA species of the Cephalopoda Octopus vulgaris and Loligo vulgaris were found to have unexpectedly high sedimentation coefficients and molecular weights. In 0.1 M-NaCl the L-rRNA (RNA from large ribosomal subunit) has the same s20 value as the L-rRNA of the mammals (30.7S), whereas the S-rRNA (RNA from small ribosomal subunit) sediments at a faster rate (20.1S) than the S-rRNA of both the mammals and the fungi (Neurospora crassa) (17.5S). The molecular weights of the L-rRNA were determined by gel electrophoresis in formamide and found to be 1.66 X 10(6) (Octupus) and 1.89 X 10(6) (Loligo); the mol.wt. of the S-rRNA of both species is 0.96 X 10(6), i.e. much larger than that of the mammals (0.65 X 10(6)) and almost coincident with that of the '23S' RNA of the prokaryotes. 2. By contrast, the less evolved Gastropoda and Lamellibranchiata (Murex trunculus and Macrocallista chione) have S-rRNA and L-rRNA species with mol.wts. of 0.65 X 10(6) and approx. 1.40 X 10(6).3. All the mature L-rRNA molecules of the cephalopoda are composed of two unequal fragments held together by regions of hydrogen-bonding having a similar, low, thermal stability in the two species; the molecular weights of the two fragments composing the L-rRNA are estimated to be 0.96 X 10(6) and 0.88 X 10(6) (Loligo) and 0.96 X 10(6) and 0.65 X 10(6) (Octupus). THe S-rRNA of both species is a continuous chain with exactly the same molecular weight (0.96 X 10(6)) as the heavier of the two fragments of the L-rRNA. 4. The secondary-structure features of the L-rRNA and S-rRNA species of the Caphalopoda were investigated by thermal 'melting' analysis in 4.0 M-guanidinium chloride; 60-70% of the residues are estimated to form short, independently 'melting' bihelical segments not more than 10 base-pairs in length. 5. Bases are unevenly distributed between non-helical and bihelical portions of the rRNA molecules, G and C residues being preferentially concentrated in bihelical comains. 6. The secondary-structure regions of the L-rRNA species of Octopus and Loligo are heterogenous, including two discrete fractions of independently 'melting' species that give rise to biphasic 'melting' profiles: a fraction consisting of shorter (G + C)-poorer segments (60-68% G + C, not more than 5 base-pairs in length) and a fraction consisting of longer (G + C)-richer segments (80-88% G + C, 5-10 base-pairs in length). No evidence for heterogeneity has been detected in the S-rRNa.

Animals↗
PubMed1978

Complexity of polysomal polyadenylated RNA in undifferentiated and differentiated neuroblastoma cells.

Using cDNA probes, we have analysed the sequence complexity and the frequency distribution of the polysomal poly(A)-containing RNA from neuroblastoma cells at two different developmental states: either as round, immature neuroblasts, or as differentiated cells exhibiting the morphological properties of mature neurons. The total complexities measured for mRNA from undifferentiated and differentiated cells are identical and correspond to approximately 7000 average-sized sequences of 1750 nucleotides distributed in the same three abundance classes. We have determined the homology between the mRNA populations corresponding to the two developmental states by heterologous cross-hybridization: all the sequence from differentiated cells are present in the polysomes of undifferentiated cells. Conversely, the mRNA from differentiated cells fails to hybridize with about 15% of hybridizable cDNA corresponding to undifferentiated cells. This difference probably results from the disappearance of some mRNA species and may be related to the terminal differentiation of neuroblastoma cells.

Animals↗
PubMed1977

Poly(A)-containing RNA in neuroblastoma: immature and differentiated cells in culture.

We have analysed the poly(A)-containing RNA from neuroblastoma cells at two different developmental states: either as round, immature neuroblasts grown in suspension, or as differentiated cells exhibiting the morphological properties of mature neurons, when attached to a culture dish. Suspension-grown and monolayer cells were pulse-labelled with tritiated uridine. The profile of cytoplasmic poly(A)-containing RNA from suspension cells is highly heterogeneous with peaks ranging from 16-30 S. The profile obtained from differentiated cells appears somewhat distinct from the previous one. This is evidenced by a relative decrease in the 26-S peak and a virtual disappearance of the 16-S component. In order to compare the 'steady-state' patterns of poly(A)-containing RNA in these two developmental stages, polysomal RNA was prepared from unlabelled cells. Following sucrose gradient sedimentation, each fraction was hybridized to [3H]poly(U). Examination of the two RNA hybridization profiles reveals striking similarities suggesting that 'steady-state' messenger populations include, on the average, the same subspecies. The 16-S fraction, which was not observed after the pulse-labelling of the monolayer culture, is detected here by hybridization to [3H]poly(U) when using polysomal poly(A)-containing RNA from monolayer cells as substrate. These results suggest that terminal differentiation of neuroblastoma cells is not accompanied by major alterations of the transcription program and is paralleled by a marked stabilization of the 16-S species.

Cell Differentiation↗
PubMed1975

Regulation of protein synthesis at the translational level in neuroblastoma cells.

Protein synthesis in reuroblastoma cells has been studied in a cell-free system. The activity of lysates from cells grown insuspension and monolayer has been compared. A higher level of activity has been found in monolayer cells. The activity of some components of the lysate that are involved in protein synthesis has been analyzed. The data suggest that the controlling step of protein synthesis in this system might be in the initiation process. The correlation between activation of protein synthesis and neurite outgrowth in monolayer cultures is discussed.

Animals↗