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C Tonelli

Publications and source records attributed to C Tonelli.

At least 19 recordsLinked to original sources
PubMed2003

KINKY POLLEN encodes a SABRE-like protein required for tip growth in Arabidopsis and conserved among eukaryotes.

In higher plants, pollen tubes and root hairs share an ancient growth process named tip growth. We have isolated three allelic Arabidopsis mutant lines showing kinky-shaped pollen tubes and, when homozygous, showing shorter and thicker root hairs. The ultrastructure of pollen tubes in these kinky pollen (kip) mutants is similar to that of the wild type; however, time-lapse studies suggest that aberrant pollen tube shape is caused by periodic growth arrests alternated with phases of tube axis reorientation. The KIP gene encodes a protein of 2587 amino acids that is predicted to be targeted to the secretory pathway. KIP mRNA was detected in all organs investigated but was most abundant in pollen and roots. KIP has putative homologues in many eukaryotes, including mammals and yeast, and is similar to the Arabidopsis SABRE gene, whose mutation causes a dwarf phenotype. The phenotype of the kip/sab double mutant suggests related functions for both genes, however, the KIP protein is mostly required for tip-growth.

Arabidopsis↗
PubMed2002

A maize r1 gene is regulated post-transcriptionally by differential splicing of its leader.

Anthocyanin biosynthesis in Zea mays is controlled by regulatory genes of the r1/b1 family that encode bHLH transcription factors. Analysis of the 381 nucleotide leader sequence of a member of this family, Sn, discloses the presence of five ATG triplets upstream of the coding region and three upstream open reading frames (uORFs) of 38, 15 and 13 amino acids respectively. RT-PCR studies revealed that a splicing event occurs in the leader region in the different tissues tested. Splicing deletes 146 nucleotides which include uORF2 and uORF3. By trans-activation experiments in maize protoplasts we find that the spliced leader, compared to the non-spliced one, reduces the number of pigmented protoplasts by four-fold. We suggest a multilevel regulation of the Sn transcription factor acting not only at the transcriptional but also at the post-transcriptional level.

5' Untranslated Regions↗
PubMed2001

Regulation of the CCAAT-Binding NF-Y subunits in Arabidopsis thaliana.

NF-Y is a CCAAT-specific binding factor composed of three distinct subunits. In vertebrates and fungi all three subunits are encoded by evolutionary conserved single copy genes. In this report we have cloned twenty-three NF-Y genes in A. thaliana, assessed their mRNA expression levels in a large number of tissues and confirmed that indeed multiple CCAAT-binding activities are present. Alignments of the genes coding for the three NF-Y subunits yield a considerable amount of information concerning the divergence/conservation of protein subdomains and of single residues within the conserved parts. Careful evaluation of mRNA expression levels by sensitive RT-PCR assays provide evidence that all three subunits have members that are ubiquitous and others that are tissue-specific and induced only after the switch to reproductive growth phase, in flowers and siliques.

Amino Acid Sequence↗
PubMed2000

Transcriptional repression by AtMYB4 controls production of UV-protecting sunscreens in Arabidopsis.

An Arabidopsis thaliana line that is mutant for the R2R3 MYB gene, AtMYB4, shows enhanced levels of sinapate esters in its leaves. The mutant line is more tolerant of UV-B irradiation than wild type. The increase in sinapate ester accumulation in the mutant is associated with an enhanced expression of the gene encoding cinnamate 4-hydroxylase, which appears to be the principal target of AtMYB4 and an effective rate limiting step in the synthesis of sinapate ester sunscreens. AtMYB4 expression is downregulated by exposure to UV-B light, indicating that derepression is an important mechanism for acclimation to UV-B in A.thaliana. The response of target genes to AtMYB4 repression is dose dependent, a feature that operates under physiological conditions to reinforce the silencing effect of AtMYB4 at high activity. AtMYB4 works as a repressor of target gene expression and includes a repression domain. It belongs to a novel group of plant R2R3 MYB proteins involved in transcriptional silencing. The balance between MYB activators and repressors on common target promoters may provide extra flexibility in transcriptional control.

Arabidopsis↗
PubMed2000

The developmental expression of the maize regulatory gene Hopi determines germination-dependent anthocyanin accumulation.

The Hopi gene is a member of the maize r1 gene family. By genetic and molecular analyses we report that Hopi consists of a single gene residing on chromosome 10 approximately 4.5 cM distal to r1. Hopi conditions anthocyanin deposition in aleurone, scutellum, pericarp, root, mesocotyl, leaves, and anthers, thus representing one of the broadest specifications of pigmentation pattern reported to date of all the r1 genes. A unique feature of the Hopi gene is that seeds are completely devoid of pigment at maturity but show a photoinducible germination-dependent anthocyanin accumulation in aleurone and scutellum. Our analysis has shown that the Hopi transcript is not present in scutellum of developing seeds but is induced only upon germination and that the simultaneous presence of both C1 and Hopi mRNAs is necessary to achieve A1 activation in scutella. We conclude that the expression pattern of the Hopi gene accounts for the germination-dependent anthocyanin synthesis in scutella, whereas the developmental competence of germinating seeds to induce anthocyanin production in scutella results from the combination of the light-inducible expression of C1 and the developmentally regulated expression of the Hopi gene.

Alcohol Oxidoreductases↗
PubMed1999

Function search in a large transcription factor gene family in Arabidopsis: assessing the potential of reverse genetics to identify insertional mutations in R2R3 MYB genes.

More than 92 genes encoding MYB transcription factors of the R2R3 class have been described in Arabidopsis. The functions of a few members of this large gene family have been described, indicating important roles for R2R3 MYB transcription factors in the regulation of secondary metabolism, cell shape, and disease resistance, and in responses to growth regulators and stresses. For the majority of the genes in this family, however, little functional information is available. As the first step to characterizing these genes functionally, the sequences of >90 family members, and the map positions and expression profiles of >60 members, have been determined previously. An important second step in the functional analysis of the MYB family, through a process of reverse genetics that entails the isolation of insertion mutants, is described here. For this purpose, a variety of gene disruption resources has been used, including T-DNA-insertion populations and three distinct populations that harbor transposon insertions. We report the isolation of 47 insertions into 36 distinct MYB genes by screening a total of 73 genes. These defined insertion lines will provide the foundation for subsequent detailed functional analyses for the assignment of specific functions to individual members of the R2R3 MYB gene family.

Arabidopsis↗
PubMed1998

Towards functional characterisation of the members of the R2R3-MYB gene family from Arabidopsis thaliana.

Transcription factors containing a conserved DNA-binding domain similar to that of the proto-oncogene c-myb have been identified in nearly all eukaryotes. MYB-related proteins from plants generally contain two related helix-turn-helix motifs, the R2 and R3 repeats. It was estimated that Arabidopsis thaliana contains more than 100 R2R3-MYB genes. The few cases where functional data are available suggest an important role of these genes in the regulation of secondary metabolism, the control of cell shape, disease resistance, and hormone responses. To determine the full regulatory potential of this large family of regulatory genes, a systematic search for the function of all genes of this family was initiated. Sequence data for more than 90 different A. thaliana R2R3-MYB genes have been obtained. Sequence comparison revealed conserved amino acid motifs shared by subgroups of R2R3-MYB genes in addition to the characteristic DNA-binding domain. No significant clustering of the genes was detected, although they are not uniformly distributed throughout the A. thaliana genome.

Amino Acid Sequence↗
PubMed1997

Ectopic anthocyanin pigmentation in maize as a tool for defining interactions between homologous regulatory factors.

The duplicated R and Sn genes are involved in the regulation of the maize anthocyanin biosynthetic pathway, encoding tissue-specific products that are homologous to the helix-loop-helix transcriptional activators. Sn determines the pigmentation of the mesocotyl, leaf basis and pericarp, while R determines pigmentation in various tissues, but not in the mesocotyl. In the progeny derived from test-crosses of R/Sn heterozygous plants, a high frequency of R plants exhibiting mesocotyl pigmentation was observed; these derivatives were defined as R*. In R* plants, the presence of this novel trait was not accompanied by the acquisition of Sn or by gross DNA rearrangements in the R profile. Accordingly, RT-PCR analysis showed that mesocotyl pigmentation in R* was attributable to the resident R gene. The occurrence of R* was observed with all R alleles tested, and was enhanced when a P component was present. The heritability of R* was shown only in the case of the standard R-r allele, which carries a functional P component. In addition, we observed that R* can influence other R alleles, transferring the ability to pigment the mesocotyl. R* is unstable, showing a tendency to return to its original state after a few generations. In R* plants there was a correlation between observed ectopic pigmentation and an increase in the level of A1 transcript but, surprisingly, not in the accumulation of R transcript. The results obtained from the analysis of test crosses of rSn/r delta plants suggest that an unlinked genetic factor accounts for the ectopic pigmentation. Concomitant occurrence of epigenetic events might explain the observed instability and reversibility noted above. Further study of this phenomenon might help to elucidate the basis of the interaction between homologous and non-homologous regulators.

Anthocyanins↗
PubMed1995

The reduced expression of endogenous duplications (REED) in the maize R gene family is mediated by DNA methylation.

The duplicated R and Sn genes regulate the maize anthocyanin biosynthetic pathway and encode tissue-specific products that are homologous to helix-loop-helix transcriptional activators. As a consequence of their coupling in the genome, Sn is partially silenced. Genomic restriction analysis failed to reveal gross structural DNA alterations between the strong original phenotype and the weak derivatives. However, the differences in pigmentation were inversely correlated with differences in the methylation of the Sn promoter. Accordingly, treatment with 5-azacytidine (AZA), a demethylating agent, restored a strong pigmentation pattern that was transmitted to the progeny and that was correlated with differential expression of the Sn transcript. Genomic sequencing confirmed that methylation of the Sn promoter was more apparent in the less pigmented seedlings and was greatly reduced in the AZA revertants. In addition, some methylcytosines were located in non-symmetrical C sequences. These findings provide an insight into Sn and R interaction, a process that we have termed Reduced Expression of Endogenous Duplications (REED). We propose that increasing the copy number of regulatory genes by endogenous duplication leads to such epigenetic mechanisms of silencing. Further understanding of the REED process may have broader implications for gene regulation and may identify new levels of regulation within eukaryotic genomes.

Anthocyanins↗
PubMed1995

[Parma Stroke Data Bank: embolic stroke].

Cerebral infarction is one of the three main causes of death in most countries. It is very frequent and, since it is more often disabiliting rather than fatal, it is of high social impact. The correct classification of patients and the accurate diagnostic definition of the various subtypes of stroke is of great prognostic and therapeutic importance since cerebral infarction is not a single entity. In this study we report our findings concerning 244 patients with embolic infarction recorded in the Parma Stroke Data Bank hospital register. Clinical features were studied (risk factors, symptomatology of the onset, degree of severity within 3 days of the onset, post-stroke complications) as were instruments readings (TAC) and evolution (outcome, mortality, personal performance and environmental integration, both 4 weeks after the clinical onset and after one year).

Aged↗
PubMed1994

Cloning and molecular analysis of structural genes involved in flavonoid and stilbene biosynthesis in grape (Vitis vinifera L.).

Genes involved in flavonoid and stilbene biosynthesis were isolated from grape (Vitis vinifera L.). Clones coding for phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin dioxygenase (LDOX) and UDP glucose:flavonoid 3-O-glucosyl transferase (UFGT), were isolated by screening a cDNA library, obtained from mRNA from seedlings grown in light for 48 h using snapdragon (Antirrhinum majus) and maize heterologous probes. A cDNA clone coding for stilbene synthase (StSy) was isolated by probing the library with a specific oligonucleotide. These clones were sequenced and when the putative products were compared to the published amino acid sequence for corresponding enzymes, the percentages of similarity ranged from 65% (UFGT) to 90% (CHS and PAL). The analysis of the genomic organization and expression of these genes in response to light shows that PAL and StSy genes belong to large multigene families, while the others are present in one to four copies per haploid genome. The steady-state level of mRNAs encoded by the flavonoid biosynthetic genes as determined in young seedlings is coordinately induced by light, except for PAL and StSy, which appear to be constitutively expressed.

Anthocyanins↗
PubMed1994

[Parma stroke data bank: atherothrombotic and lacunar stroke].

In an epidemiological research about stroke, we studied 235 patients with atherothrombotic brain infarctions and 81 patients with lacunes. It was a longitudinal study concerning patients admitted to our Medical Division during the acute phase and followed up for one year after the onset. We report some anamnestic data, the frequency of positive brain CT scan, main risk factors, symptoms at the onset, severity degree of the stroke within the first 72 hours, complications during, and outcome after, the first four weeks, including personal performances and environmental fitness, mortality rate and frequency of relapses. We also report some of these data after one year from the acute episode.

Adult↗
PubMed1993

Antiparallel expression of the sense and antisense transcripts of maize alpha-tubulin genes.

In all eukaryotes alpha- and beta-tubulins are encoded by small families of closely related genes and are highly conserved. In Zea mays, at least six different alpha-tubulin coding sequences are known. We describe the isolation from scutellar nodes of the maize inbred line W22 of a clone (CTM5) coding for an alpha-tubulin. On the basis of the 3' end nucleotide sequence, this clone can be assigned to the already reported tua4 gene. Northern analysis demonstrates that CTM5 encodes a 1.5 kb transcript, which is expressed in different tissues of the seed and of the seedling. In order to define the spatial and temporal expression of alpha-tubulin genes, in situ hybridization experiments were performed on these tissues. Unexpectedly, a specific signal was detected with both antisense and sense RNA strands. Temporal and spatial distribution of the two RNAs, however, shows that high levels of the two transcripts are always discordant. In tissues where sense transcripts are highly abundant (embryos at various developmental stages, root tips, pollen grains), the antisense transcripts are expressed in relatively small amounts, while in pericarp, coleoptile, leaves, and scutellar node, where antisense transcripts accumulate, the sense transcript only reaches a very low level. Northern analysis using single-stranded DNA probes confirmed the presence of an antisense transcript of 1.5 kb, prompting speculation about the role of this transcript in the regulation of the expression of alpha-tubulin genes.

Base Sequence↗
PubMed1993

Molecular homology among members of the R gene family in maize.

The R gene family determines the timing, distribution and amount of anthocyanin pigmentation in maize. This family comprises a set of regulatory genes, consisting of a cluster of several elements at the R locus, on chromosome 10, the Lc and Sn gene lying about two units R distal and B on chromosome 2. Each gene determines a tissue-specific pigmentation of different parts of the seed and plant. The proposed duplicated function of R, Sn, Lc and B loci is reflected in cDNA sequence similarity. In this paper an extensive analysis of the predicted proteins of the R, Sn, Lc and B genes together with a search for putative sites of post-translational modification is reported. A comparison with the prosite database discloses several N-glycosylation and phosphorylation sites, as well as the basic Helix-Loop-Helix (HLH) domain of transcriptional activators. Sn, Lc, and R-S show a high conservation of these sites, while B is more divergent. Analysis of the 5' leader of mRNA sequences discloses the presence of five ATG triplets with two upstream open reading frames (uORFs) of 38 and 15 amino acids and a loop structure indicating a possible mechanism of control at the translational level. It is conceivable that possible mechanisms acting at the translational and post-translational level could modulate the expression and the activation of these transcription factors. Northern analysis of various tissues of different R alleles highlights a strict correlation between pigment accumulation in different tissues and the expression of the regulatory and structural genes suggesting that the pattern of pigmentation relies on a mechanism of differential expression of the members of the R family. Analysis of the Sn promoter discloses the presence of several sequences resembling binding sites of known transcription factors (as GAGA and GT) that might be responsible for the spatial and light-induced expression of this gene. Two regions include a short sequence homologous to the consensus binding site of the B-HLH domain suggesting a self-regulatory control of the Sn gene.

Amino Acid Sequence↗
PubMed1993

Prevalence and prognostic value of peripheral arterial disease in stroke patients.

As atherosclerosis is a multi-systemic disease, each patient presenting clinical manifestation of atherosclerosis such as a stroke or RIND should be, from a vascular point of view, globally evaluated. The availability of Doppler ultrasound technique enables us to discover the presence of Peripheral Artery Disease (PAD) which is not always overt in the patient's history. Furthermore the presence of PAD is associated with a poorer prognosis in stroke patients.

Aged↗
PubMed1991

Genetic and molecular analysis of Sn, a light-inducible, tissue specific regulatory gene in maize.

The Sn locus of maize is functionally similar to the R and B loci, in that Sn differentially controls the tissue-specific deposition of anthocyanin pigments in certain seedling and plant cells. We show that Sn shows molecular similarity to the R gene and have used R DNA probes to characterize several Sn alleles. Northern analysis demonstrates that all Sn alleles encode a 2.5 kb transcript, which is expressed in a tissue-specific fashion consistent with the distribution of anthocyanins. Expression of the Sn gene is light-regulated. However, the Sn: bol3 allele allows Sn mRNA transcription to occur in the dark, leading to pigmentation in dark-grown seedlings and cob integuments. We report the isolation of genomic and cDNA clones of the light-independent Sn: bol3 allele. Using Sn cDNA as a probe, the spatial and temporal expression of Sn has been examined. The cell-specific localization of Sn mRNA has been confirmed by in situ hybridization using labelled antisense RNA probes. According to its proposed regulatory role, expression of Sn precedes and, in turn, causes a coordinate and tissue-specific accumulation of mRNA of structural genes for pigment synthesis and deposition, such as A1 and C2. The functional and structural relationship between R, B, Lc and Sn is discussed in terms of an evolutionary derivation from a single ancestral gene which gave rise this diverse gene family by successive duplication events.

Acyltransferases↗
PubMed1991

Effects of intraperitoneal chemotherapy on anastomotic healing in the rat.

The effect of perioperative intraperitoneal (ip) (2 mg/kg) vs intravenous (iv) (1.5 mg/kg) mitomycin-C on healing of intestinal anastomoses was studied in rats after jejunal section and anastomosis. When the animals were killed 7 days after surgery 52.8% in the ip group had an anastomotic leak (41.2% causing death of the animals), compared to 20% in the iv group and none in the control group. Mean anastomotic bursting pressure was 156 mm Hg in the ip group, 178 mm Hg in the iv group, and 203 mm Hg in controls (P less than 0.01). Hydroxyproline content of the intestinal segment containing the anastomosis was 2.26 micrograms/mg in the ip group, 3.49 in the iv, and 4.91 in controls (ip vs controls, P less than 0.01). Histological examination of the anastomoses in rats given ip mitomycin showed significantly "slower" anastomotic healing than in iv rats and controls. Electron microscopy showed that the mean diameter of collagen fibers was significantly smaller (P less than 0.05) in ip rats (34 nm) than iv (51 nm) and controls (79 nm). An intraoperative bolus of mitomycin thus significantly impaired the healing of a jejunal anastomosis in the rat, more so after ip than iv injection. Thus in clinical practice ip adjuvant chemotherapy after surgery should perhaps be delayed until wound repair has reached an advanced stage.

Anastomosis, Surgical↗