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L Natali

Publications and source records attributed to L Natali.

At least 19 recordsLinked to original sources
PubMed2006

Distribution of Ty3-gypsy- and Ty1-copia-like DNA sequences in the genus Helianthus and other Asteraceae.

Two repeated DNA sequences, pHaS13 and pHaS211, which revealed similarity to the int gene of Ty3-gypsy retrotransposons and the RNAse-H gene of Ty1-copia retroelements, respectively, were surveyed in Asteraceae species and within the genus Helianthus. Southern analysis of the genome of selected Asteraceae that belong to different tribes showed that pHaS13- and pHaS211-related subfamilies of gypsy- and copia-like retroelements are highly redundant only in Helianthus and, to a lesser extent, in Tithonia, a Helianthus strict relative. However, under low stringency posthybridization washes, bands were observed in almost all the other Asteraceae tested when pHaS13 was used as a probe, and in several species when pHaS211 was hybridized. FISH analysis of pHaS13 or pHaS211 probes was performed in species in which labelling was observed in Southern hybridizations carried out under high stringency conditions (Helianthus annuus, Tithonia rotundifolia, Ageratum spp., Leontopodium spp., Senecio vulgaris for pHaS13, and H. annuus, Tithonia rotundifolia, and S. vulgaris for pHaS211). Scattered labelling was observed over all metaphase chromosomes, indicating a large dispersal of both Ty3-gypsy- and Ty1-copia-like retroelements. However, preferential localization of Ty3-gypsy-like sequences at centromeric chromosome regions was observed in all of the species studies but one, even in species in which pHaS13-related elements are poorly represented. Ty1-copia-like sequences showed preferential localization at the chromosome ends only in H. annuus. To study the evolution of gypsy- and copia-like retrotransposons in Helianthus, cladograms were built based on the Southern blot hybridization patterns of pHaS13 or pHaS211 sequences to DNA digests of several species of this genus. Both cladograms agree in splitting the genomes studied into annuals and perennials. Differences that occurred within the clades of perennial and annual species between gypsy- and copia-like retroelements indicated that these retrotransposons were differentially active during Helianthus speciation, suggesting that the evolution of the 2 retroelement families was, within limits, independent.

Amino Acid Sequence↗
PubMed2003

Analysis of a dehydrin encoding gene and its phylogenetic utility in Helianthus.

Dehydrins are ubiquitous plant proteins, synthesized in late stages of plant embryo development and following any environmental stress involving dehydration. With the aim to study the evolution of such a stress-responsive gene within Helianthus and to test the possibility of using this gene for phylogenetic studies, fragments of the same dehydrin gene were isolated by PCR and sequenced in 16 wild Helianthus species or subspecies. All isolated sequences included the typical dehydrin domains (Y, S and K), a portion of 3'-UTR and an intron, inserted in the same position within the S domain-encoding region. The number of nucleotide substitutions (both synonymous and nonsynonymous) was calculated keeping separate the different gene regions, and differences occur even among coding domains, indicating that evolutionary constraints act differently on each region. The occurrence of indels and/or insertions was also observed. At the deduced protein level, the calculation of isoelectric point, molecular weight and the percentage of alpha-helix showed a diversification of biochemical properties of this protein between annual and perennial Helianthus species. Phylogenetic trees were built by the maximum-likelihood, maximum-parsimony, and neighbor-joining methods. In all cases the same topology was observed; perennial and annual species form a supported clade, and H. annuus was separated from the other annuals and from perennials. These data support the use of this stress-responsive gene to study the phylogeny of Helianthus.

Amino Acid Sequence↗
PubMed2002

Sequence variability of a dehydrin gene within Helianthus annuus.

Dehydrins are proteins produced during the late stages of plant embryo development and following any environmental stimulus involving dehydration. In order to investigate the variability of a dehydrin-encoding gene (Dhn1) in cultivated and wild sunflower (Helianthus annuus) genotypes, near-complete alleles were isolated by the polymerase chain reaction and sequenced. All of the isolated sequences were found to contain the typical dehydrin domains, and interrupted by an intron. The number of nucleotide substitutions and indels per site was calculated. With respect to the overall sequence, variation in both the coding and noncoding [intron and 3'-UTR (untranslated region)] sequences was much larger among wild accessions than among cultivars. No variation was observed in 3'-UTRs from cultivated sunflowers. Different coding regions showed a different numbers of synonymous and nonsynonymous substitutions. The Y and K domains were the most conserved in both wild and cultivated genotypes. Sequence analysis of the deduced dehydrin proteins showed that nucleotide substitutions in wild accessions should also determine large biochemical differences at the protein level. All of the isolated alleles were however functional, at least at the transcription level. To our knowledge these are the first data on intraspecific genetic variability of such a stress response gene. The low variability of dehydrin genes from cultivated sunflower is discussed in relation to the origin of sunflower cultivars. The possibility of rescuing general genetic variability through crosses to wild accessions of H. annuus rather than using wild Helianthus species is also discussed.

Amino Acid Sequence↗
PubMed2002

Ty1 /copia- and Ty3 /gypsy-like DNA sequences in Helianthus species.

Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.

Amino Acid Sequence↗
PubMed2002

Cancer testis antigens expression in mesothelioma: role of DNA methylation and bioimmunotherapeutic implications.

Recent evidences suggest that malignant mesothelioma may be sensitive to immunotherapy; however, little is known about malignant mesothelioma-associated tumour antigens. Focusing on cancer/testis antigens, the expression of well-characterised immunogenic tumour-associated antigens was investigated in malignant mesothelioma cells. At variance with MAGE-4 and NY-ESO-1, malignant mesothelioma cells frequently expressed MAGE-1, -2 and -3, GAGE 1-2, GAGE 1-6, SSX-2 and SSX 1-5, and distinct malignant mesothelioma cells concomitantly expressed at least four cancer/testis antigens. Additionally, the tumour-associated antigens RAGE-1 was expressed at high levels in both benign and malignant mesothelial cells. Lastly, treatment with the DNA hypomethylating agent 5-aza-2'-deoxycytidine induced and up-regulated the expression of the cancer/testis antigen examined in malignant mesothelioma cells. Overall, these findings strongly suggest that cancer/testis antigens-based immunotherapy may represent a suitable therapeutic approach to malignant mesothelioma, and foresee the clinical use of 5-aza-2'-deoxycytidine to design new chemo-immunotherapeutic strategies in malignant mesothelioma patients.

Animals↗
PubMed2001

White and UV light effects on cell nuclei in the aurea genotype of Lycopersicum esculentum L.

The effects of white light and UV light on chromosome endoreduplication, chromatin conformation and RNA synthesis were analysed in the hypocotyl cortical cylinder of the cv UC-105 of tomato and its isogenic mutant aurea, deficient in photoactive phytochrome A at the etiolated stage. Short white light or UV irradiations were administered to 4-day-old seedlings grown in the dark. White light had no effect on the mean ploidy level in the cv UC-105, but it increased the ploidy level in the aurea mutant. This is explained by hypothesizing that phytochrome inhibits endoreduplication, while cryptochrome stimulates it. UV light produced a higher ploidy in both genotypes, possibly because of residual action of cryptochrome at this wavelength or of specific UV-responsive photoreceptor. White light or UV light transiently increased heterochromatin amounts in the diploid nuclei of cv UC-105, and produced higher levels of RNA transcription than continuous dark. It is suggested that these responses were mediated by phytochrome, because they were lacking in the aurea mutant.

Cell Nucleus↗
PubMed2000

Characterization and expression of DNA sequences encoding putative type-II metallothioneins in the seagrass Posidonia oceanica.

Posidonia oceanica is a marine phanerogam, largely widespread in the Mediterranean sea, representing an important food substrate for many marine organisms. A progressive reduction of P. oceanica meadows has been reported, due to anthropogenic coastal activity. Studying mechanisms by which this species responds to environmental stresses, three DNA sequences putatively encoding metallothioneins (MTs) have been isolated, by PCR. Two sequences, Pomt2a (accession no. AJ249603) and Pomt2b (accession no. AJ249602), show high similarities with genes encoding type-II MTs and are interrupted by two and one intron, respectively. The third sequence, Pomt2c (accession no. AJ249604), is supposed to be a pseudogene, originated by retrotranscription of the Pomt2b mRNA. These sequences belong to a multigene family with at least five members. Northern hybridizations indicated that MT transcripts accumulation is constitutive and seasonally regulated. MT encoding RNAs increase after rhyzome harvesting and (at a lesser extent) after 15 d of cultivation in an aquarium. As for animal MTs, transcripts accumulation is observed also after exposure to trace metals such as copper and cadmium. In the case of copper, the effect depends on concentration. Finally, taking into consideration the great interest in studying the biogeochemical cycle of mercury in the Mediterranean basin and since P. oceanica is commonly considered a bioindicator of this metal, the effect of mercury treatments on the accumulation of MT transcripts has been analyzed: in only a few experiments a small increase in the level of transcripts was recorded, suggesting that MTs are not key elements in the mercury accumulation by this species.

Amino Acid Sequence↗
PubMed1999

Expression of a dehydrin gene during embryo development and drought stress in ABA-deficient mutants of sunflower (Helianthus annuus L.).

The synthesis of a particular class of proteins, the dehydrins, is a common response to drought in plants. Dehydrins are known to be synthesized by the cell in response to abscisic acid, which represents a link between environment and nuclear activity, though dehydrin genes may be expressed even constitutively. We have investigated the relationship between abscisic acid (ABA) and accumulation of a dehydrin mRNA in sunflower, in which a dehydrin cDNA (HaDhnla) was isolated. In particular, we studied changes in the steady-state level of dehydrin transcripts in two mutants for ABA synthesis and accumulation: nd-1 (an albino, non-dormant and lethal mutant with a very low ABA content and no ABA accumulation in response to stress) and w-1 (a wilty mutant, with reduced ABA accumulation) during embryo and plantlet development and drought stress. Differences between genotypes were observed through embryogenesis: w-1 shows a lower content of dehydrin transcripts in the early stages compared to control plants, indicating that ABA affects dehydrin mRNA accumulation; however, dehydrin transcripts level appears independent of ABA content in late embryogenesis. Also during drought stress in w-1 adult leaves, ABA is not quantitatively related to the steady-state level of the HaDhn1a transcripts. Finally, data on nd-1 mutant show a high level of dehydrin transcripts after drought stress in plantlet cotyledons and leaflets. These results indicate the existence of two regulation pathways of HaDhn1a transcripts accumulation, an ABA-dependent and an ABA-independent one, which may have cumulative effects.

Abscisic Acid↗
PubMed1996

Cytophotometric determination of heterochromatin base composition in interphase nuclei of plant cells.

The use of DNA base-specific fluorochromes and static cytophotometry at different thresholds of fluorescence intensity is proposed for studying the base composition of differently condensed chromatin fractions in plant interphase nuclei. Results are reported of such analyses on nuclei from leaflets of Posidonia oceanica and Helianthus annuus, which confirm other findings obtained on the same materials by biochemical and molecular methods.

Base Composition↗
PubMed1994

Treatment of type C chronic active hepatitis with interferon-alpha 2a. Treatment duration does not influence biochemical remission but does decrease the relapse rate.

Few data are as yet available on the influence of interferon (IFN) treatment duration on biochemical remission and posttreatment relapse of chronic type C hepatitis. We investigated whether duration of recombinant IFN-alpha 2a treatment influences the remission and relapse rates in type C chronic active hepatitis (CAH). Sixty-two CAH patients were randomly assigned to receive 3 MU of i.m. recombinant IFN-alpha 2a three times per week for either 3 (group A, 32 patients) or 6 (group B, 30 patients) months. A complete biochemical remission was cumulatively observed in 62.5 and 63.3% of patients in groups A and B, respectively (p = NS). One and two patients in groups A and B, respectively, showed a biochemical relapse during treatment. In all cases biochemical remission was observed within the first 3 months of treatment. Among responders, 84.2 and 52.9% (p = 0.04) cumulatively had relapses in groups A and B, respectively. We conclude that IFN treatment duration does not influence the biochemical remission rate in type C CAH, but lowers the relapse rate of those who are treated for a longer period. The IFN treatment should be stopped if the patient is a nonresponder after 3 months of treatment. In responders, treatment should be continued for at least 6 months.

Adult↗
PubMed1991

Incidence and indications for cholecystectomy in a public health district of a small town in central Italy.

There are major differences in cholecystectomy rates between different countries. We prospectively recorded all gallbladder operations in L'Aquila, Italy (a small town in central Italy with a population of about 98,700 inhabitants) from June 15, 1987 to June 14, 1988. During that year 210 cholecystectomies were performed (women and girls = 71.4%), for a calculated yearly incidence rate of 0.212%. Cholecystectomy was elective in 85.2%, urgent in 8.6%, and was performed in the course of other abdominal operations (mainly colon cancer) in the remaining 6.2%. Half (44.3%) of the patients were operated on because of at least one episode of biliary colic, and 9.0% because of an acute complication. Respectively 16.2% and 30.5% were operated on because of dyspeptic symptoms or to prevent symptoms or complications. Gallstones were not found in six, while exploration of the common bile duct revealed gallstones in seven patients. The chemical analysis showed that 84.7% were cholesterol stones (mixed or pure). We presume that most observed differences in cholecystectomy rates between different Western countries are more likely owing to differences in indications for surgery rather than to differences in prevalence of gallstones.

Cholecystectomy↗
PubMed1989

5-azacytidine-induced tumorous transformation and DNA hypomethylation in Nicotiana tissue cultures.

The phenomenon of habituation is considered in plant tissue cultures to be a real process of chemical tumorogenesis; the cultures acquire the capacity of autonomous growth in a hormone-free medium under the influence of a variety of chemical and physical agents. Treatments with 5-azacytidine (AzaC) of in vitro cultured cells of the Nicotiana glauca x N. langsdorffii nontumorous hybrid (NNT) during the culture cycle led to the induction of a habituated phenotype. The repetitive DNA sequences showed a significant lower level of endogenous methylation in the treated cells in comparison with the normal ones. It is worth noting that it was impossible until now to habituate this strain by conventional methods and that the treatments were effective only in the first 5 days of subculturing; various evidence (cytological and biochemical) pointed out a phenomenon of DNA amplification, occurring in the same period. Moreover, analysis of DNA from control and treated cells shows the induction of variations in the endogenous methylation pattern by AzaC in a critical period of cell culture. These results suggest that demethylation can act as a switch from hormone-dependent to autonomous proliferation by activation of genes coding for or regulating the synthesis of growth factors.

5-Methylcytosine↗
PubMed1987

[Serum levels of magnesium in hepatic cirrhosis].

In a group of 50 patients with liver cirrhosis compared with a group of 50 clinically healthy subjects serum magnesium levels were determined. The patients were divided according the aetiology of liver cirrhosis and to the presence or not of ascite and cholestasis. The serum magnesium levels were related to the main laboratory tests used in liver cirrhosis. The patients present a significant decrease of serum magnesium levels in comparison to controls. The patients with alcoholic cirrhosis of the liver and with ascite have significant lower magnesium levels in comparison with the patients with post-hepatitis cirrhosis and with patients without ascite. There is a significant correlation between serum magnesium levels and serum levels of aldosterone, albumin, gamma-glutamyl transpeptidase and total pool of bile acids. Direct and indirect effects of alcohol, a secondary hyperaldosteronism, the use of diuretics, and hypoalbuminaemia could account for magnesium serum level decrease in liver cirrhosis.

Aged↗
PubMed1986

Amplification of nuclear DNA sequences during induced plant cell dedifferentiation.

Cell dedifferentiation has been induced in Vicia faba roots by removing the whole meristem (decapitation). When centrifuged to equilibrium in CsCl density gradient, the DNA from dedifferentiating tissues forms a heavier satellite, not occurring in the DNA from differentiated tissues. Most of the radioactivity after [3H]thymidine feeding is found in the satellite DNA. Its sequences have a well defined nuclear localization, as shown by in situ hybridization experiments. These results indicate amplification of G + C-rich nuclear DNA sequences during cell dedifferentiation.

Cell Differentiation↗
PubMedDate not supplied

Hepatic encephalopathy: lack of changes of gamma-aminobutyric acid content in plasma and cerebrospinal fluid.

The aim of the study was to verify the role of gamma-aminobutyric acid in the pathogenesis of hepatic encephalopathy occurring in cirrhotic patients by attempting to correlate plasma and cerebrospinal fluid content of authentic gamma-aminobutyric acid with the neurological manifestations of hepatic encephalopathy. For this purpose, plasma and cerebrospinal fluid gamma-aminobutyric acid levels were measured by means of mass fragmentography in 17 cirrhotic patients with hepatic encephalopathy and in 6 cirrhotics without neurological symptoms. Moreover, in all patients, a second sample was obtained during the clinical course of hepatic encephalopathy. The mean plasma and cerebrospinal fluid gamma-aminobutyric acid levels were not different in patients with or without hepatic encephalopathy and did not change during the evolution of the neurological symptoms. The lack of changes in the gamma-aminobutyric acid content in plasma and cerebrospinal fluid during hepatic encephalopathy is in contrast with the hypothesized importance of increased entry into the brain of gamma-aminobutyric acid in the pathogenesis of hepatic encephalopathy.

Adult↗