Intragenomic recombination between homologous regions of genes II and IV promotes formation of bacteriophage f1 miniphages.

Heterogeneity within and between primary colorectal carcinomas and matched metastases as revealed by analysis of Ki-ras and p53 mutations

Analysis of the genetic status of Ki-ras and p53 in primary colorectal carcinomas and matched colorectal liver metastasis from 30 patients reveals an overall heterogeneity both within and between the two tumoral tissues. Both genes were found mutated with a similar frequency in both tissues; however, identical mutations in primary tumor and matched metastasis were found less frequently in the case of the Ki-ras than the p53 gene. Only in three cases the same p53 and Ki-ras mutations found in the primary tumor were found also in the metastasis. In several metastatic specimens the DNA bearing a mutation detected also in the primary tumor appears significantly less abundant than the wild-type …

Characterization of transfected HT-29 cells expressing the oncogenic Ras isoform KrasG13D.

Point mutations in codon 12 and 13 of K-ras are frequently found in DNA of colorectal cancer. It has been suggested that particular mutations at these sites may be associated with specific tumour phenotypes. To shed light on the molecular mechanisms on which depends this specificity we set up a system of HT-29 cells stably transfected with a cDNA coding for K-rasG13D under the control of an inducible promoter. Proliferation assay performed on one of the positives clones, showed a decreased growth rate in response to K-rasG13D expression and preliminary gene expression analysis showed an up-regulation of the cell-cycle inhibitor p21 WAF1.

Differential Gene Expression During Corneal Wound Healing

Effects of different ras mutations on colorectal cancer cells

Caratterizzazione dell'antigene AMA1 in ceppi di Babesia bigemina isolati in Italia

Babesia bigemina is an endemic parasite in different parts of the world, including Europe and the Americas. One of the few genes characterized in this species codifies for the apical membrane antigen 1 (AMA-1), a transmembrane antigen recently identified. We characterized the ama-1 gene from three Italian B. bigemina strains. Italian sequences were compared to those of the Australian strain. The results obtained confirmed that this newly described ama-1 gene is highly conserved among Italian and foreign strains, which has implications for vaccine development.

Lipocalin-2 up-regulation in patients with dry eye. Congresso ARVO 2006.

Intrachromosomal recombination of the c-myc locus leading to gene amplification

Possible relation between genetic recombination and amplification within the c-myc locus in a case of primary colorectal carcinoma

Genotyping of sicilian Ophrys (Orchidaceae) from Parco delle Madonie

Lipocalin-2-up regulation in patients with dry eye

Gene expression profiling of HT-29 cells in response to induction of oncogenic H and K-ras.

1909-1910: La 'conversione' di Morgan al modello dell'ereditarietà indiretta.

Omaggio a Charles Darwin: 1809-2009: duecento anni di evoluzionismo

DUE DIFFERENTI MECCANISMI MOLECOLARI COINVOLTI NEL FENOMENO DELL'AMPLIFICAZIONE GENICA IN UN CASO DI CARCINOMA COLORETTALE

Havep53 gene mutations and protein expression a different biological significance in colorectal cancer?

p53 alterations are considered the most common genetic events in many types of neoplasms, including colorectal carcinoma (CRC). These alterations include mutations of the gene and/or overexpression of the protein. The aim of our study was to assess whether in 160 patients undergoing resective surgery for primary operable CRC there was an association between p53 mutations and protein over-expression and between these and other biological variables, such as cell DNA content (DNA-ploidy) and S-phase fraction (SPF), and the traditional clinicopathological variables. p53 mutations, identified by PCR-SSCP-sequencing analysis, were found in 68/160 patients (43%) and positive staining for p53 prote…

Analisi comparativa dei livelli di RNA in cellule in coltura trattate con dexametasone

Intrachromosomal recombination of c-myc locus leading to gene amplification

Morphological and SSR molecular markers based genetic variability in 39 olive cultivars ( Olea europaea L.) originated in Southern Italy

Optimized RNA extraction and northern hybridization in streptomycetes.

Abstract Northern blot hybridization is a useful tool for analyzing transcript patterns. To get a picture of what really occurs in vivo, it is necessary to use a protocol allowing full protection of the RNA integrity and recovery and unbiased transfer of the entire transcripts population. Many protocols suffer from severe limitations including only partial protection of the RNA integrity and/or loss of small sized molecules. Moreover, some of them do not allow an efficient and even transfer in the entire sizes range. These difficulties become more prominent in streptomycetes, where an initial quick lysis step is difficult to obtain. We present here an optimized northern hybridization protoc…

Differential effects of oncogenic H- and K-ras expression on HT-29 colorectal carcinoma cell line.

The Ras oncogene is mutated in about 30% of the human tumors and its mutations are always point mutations concerning codon 12, 13 and 61. These mutations cause in the proteins a reduced GTPase activity, so that they become constitutively active. In human cells there are three main isoforms of Ras (H, K, N-ras) which can trigger alternative pathways of signal trasduction. In order to investigate the effects of expression of different oncogenic Ras isoforms in colorectal carcinoma cells (HT-29), we obtained stable clones of HT-29 cells transfected with cDNAs codifying H-RasG12V and K-Ras G12V called respectively H12 and K12 and K-RasG13D called K13, under the control of an hormone-inducible p…

Transcription in bacteriophage f1-infected Escherichia coli: Very large RNA species are synthesized on the phage DNA

Fractionation of pulse-labeled RNA extracted from E. coli cells infected with phage f1 and hybridization of this RNA to f1 DNA reveals that very large species are synthesized on the phage genome. Hybridization of the RNA to specific fragments of f1 DNA shows that, in the infected cell, at least one mRNA is present into which the sequences of genes III, VI, and I are all transcribed together. This result fully explains the polar effect shown by gene III mutants on the expression of genes VI and I (Pratt et al. 1966).

Effescts of different RAS mutations on colorectal cancer cells

DNA Extraction From Orthoptera Museum Specimens

We describe a procedure for rapid purification of high quality DNA from either fresh or dry Orthoptera, suitable for the PCR amplification of DNA regions more than 800 bp long (even from oldest specimens), which allows genetic analyses on animals from collections without the complete specimen disruption.

Transcription in bacteriophage f1-infected Escherichia coli: RNA synthesized on DNA of deletion mutant PII shows the existence of a two-site terminator.

Two different transcripts are synthesized on the DNA of deletion mutant PII of bacteriophage f1 in E. coli cells infected with this miniphage. Both RNA species appear to be primary transcripts and differ by about 100 nucleotides at their 3'OH end. Mapping of these molecules on the miniphage genome suggests that a two-site terminator is active at the end of the I region of transcription of bacteriophage f1.

Two distinct amplification events of the c-myc locus in a colorectal tumour.

Southern hybridisation of genomic DNA extracted from a human primary colorectal carcinoma revealed amplification of a fragment containing the wild-type c-myc locus. Two additional rearranged DNA fragments, lying upstream of c-myc, fused to distant non-contiguous sequences from the same chromosome, with an opposite configuration (head to head vs. head to tail), were also found to be amplified. Sequences analysis suggested that these rearrangements resulted from illegitimate recombination at two distinct points within the DNA sequence just upstream of the c-myc ORF and further that these events triggered two different amplification mechanisms, only one of which, involving a strand invasion ev…

Babesia bigemina Apical Membrane Antigen-1: features of the gene and predictive information of the protein from Italian strains

Babesia bigemina is a tick-borne haemoparasite affecting cattle in different parts of the world. One of the few antigens characterized in this species codifies for the Apical Membrane Antigen 1 (AMA-1), a transmembrane protein recently identified. In this work, we characterized the ama-1 gene from four Italian B.bigemina strains, two obtained from Ragusa, Sicily (ITA1 and ITA3), one obtained from Benevento, Campania (ITA2) and one coming from Perugia, Umbria (ITA4). Italian sequences were compared to the Australian strain, whose sequence is available in the Sanger Institute web site, and to some strains coming from different parts of the world. This study provides useful information on the …

Role of H-RAS and K-RAS oncogenes on mucin expression in colorectal carcinoma

RNA stabillity as determinant of polarity in gene III of phage f1

Studio morfologico dei taxa afferenti al genere ficusL. presenti nell'Orto botanico e nei giardini storici di Palermo

Lipocalin-2 up-regulation in patients with dry eye.

AMPLIFICAZIONE E RIARRANGIAMENTO NEI TUMORI COLORETTALI

Studio della variabilità genetica in cultivar di olivo (Olea europaea L.) del germoplasma dell’Italia meridionale mediante l’utilizzo di caratteri bio-metrici e marcatori molecolari microsatelliti

RNaseE-mediated mRNA degradation as determinant of polarity in phage f1.

RNA processing and degradation are important steps in the regulation of gene expression. The genes present on the DNA of filamentous phage f1 are expressed at very different levels. A group of genes which are expressed at a very low level (genes III, VI, I and IV is located in the region IF of the phage DNA. The current model proposes that expression of the genes III. VI and I (which form an operon) is regulated by readthrough transcription at a weak terminator located at the end of gene III, while that of gene IV by a terminator located at the end of it. In contrast with this, we found that very long transcripts complementary to the entire f1 DNA are synthesized in the infected cells and t…

Havep53gene mutations and protein expression a different biological significance in colorectal cancer?*

p53 alterations are considered the most common genetic events in many types of neoplasms, including colorectal carcinoma (CRC). These alterations include mutations of the gene and/or overexpression of the protein. The aim of our study was to assess whether in 160 patients undergoing resective surgery for primary operable CRC there was an association between p53 mutations and protein overexpression and between these and other biological variables, such as cell DNA content (DNA-ploidy) and S-phase fraction (SPF), and the traditional clinicopathological variables. p53 mutations, identified by PCR-SSCP-sequencing analysis, were found in 68/160 patients (43%) and positive staining for p53 protei…

Direct Identification of Each Specific Mutation in Codon 12 and 13 of ci-ki-ras2 by SSCP Analysis

We compared the SSCP behaviour of the DNA fragments containing c-ki-ras 2 wild type 12 and 13 codons or each of the 12 possible point mutated sequences in these two codons. We found that a single electrophoresis condition was sufficient to distinguish each specific mutation from the other 11 and from the wild type sequence. This observation makes it possible to identify each specific mutation directly by SSCP without any need for reamplification and sequencing.

RNA quality control: RppH activity allows selective removal of nonsense messages in E. coli.

Polar effect, the reduced expression level of sequences downstream to mutations reducing translation efficiency, is usually due to transcription termination or inefficient translation reinitiation. Untranslated mRNAs are known to be quickly degraded, probably because of their increased accessibility to degradative enzymes due to the absence of translating ribosomes. In III-VI-I operon of phage f1, a strong polar effect is observed in a gIII 5’ proximal nonsense mutant, resulting in a very fast, RNaseE mediated, degradation of any full-length mRNA. RNaseE is a key component of the E. coli degradosome, the major RNA processing/degrading machinery. Its endonucleolytic activity is strongly enha…