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S Prat

Publications and source records attributed to S Prat.

36 records · Page 2Linked to original sources
PubMed1994

Cloning and characterization of a cathepsin D inhibitor gene from Solanum tuberosum L.

A DNA clone encoding a cathepsin D inhibitor CathInh was isolated from a potato genomic library using a CathInh cDNA as hybridization probe. The amino acid sequence of the coding region is nearly identical with a CathInh cDNA and CathInh proteins previously isolated from a tuber-specific cDNA library and from tubers, respectively. Analysis of GUS activity resulting from expression of chimeric CathInh promoter-GUS genes in transgenic potato plants revealed expression exclusively confined to potato tubers. No GUS activity could be detected in any other organ of the transgenic plants either constitutively or after wounding or treatment with abscisic and jasmonic acid (JA). Interestingly, part of the promoter region of the CathInh gene, essential for GUS activity in tubers, shows striking similarity to promoter regions of tuber-specific class I patatin genes.

Amino Acid Sequence↗
PubMed1994

A dominant negative mutant of PG13 suppresses transcription from a cauliflower mosaic virus 35S truncated promoter in transgenic tobacco plants.

TGA1a and PG13 constitute a family of tobacco basic leucine zipper (bZIP) proteins that bind to activating sequence-1 (as-1), which is one of the multiple regulatory cis elements of the cauliflower mosaic virus (CaMV) 35S promoter. After truncation of the CaMV 35S promoter down to position -90 (CaMV 35S [-90] promoter), transcription stringently depends on the presence of as-1, which is recognized by nuclear DNA binding proteins called ASF-1. The role of the TGA1a/PG13 bZIP family in the formation of ASF-1 and in transcriptional activation of the CaMV 35S (-90) promoter has not yet been demonstrated in vivo. We constructed transgenic tobacco plants expressing a mutant of potato PG13, which lacks its wild-type DNA binding domain. This mutant acts as a trans-dominant inhibitor of ASF-1 formation and of expression from the CaMV 35S (-90) promoter, showing that PG13 can specifically interact with proteins necessary for these processes. Although we did not observe any other obvious phenotypic changes, these transgenic plants are a potentially valuable tool in identifying whether TGA1a and PG13 are involved in controlling promoters encoded in the plant genome.

Bacterial Proteins↗
PubMed1994

Functional analysis of a leucine aminopeptidase from Solanum tuberosum L.

A protein encoded by a potato cDNA homologous to a leucine aminopeptidase (LAP) from bovine lens (Hildmann et al. 1992) was expressed in Escherichia coli cells and biochemically characterized by hydrolysis of leucine p-nitroanilide. Activity was highest under alkaline conditions with an optimum at about pH 10. Maximal activities were measured at 65 degrees C. Apart from leucine p-nitroanilide the enzyme could also efficiently hydrolyze the p-nitroanilides of arginine and methionine. Complete inhibition of the enzyme was achieved by incubating bacterial extracts with bestatin and EDTA, which classifies the enzyme as a metalloprotease belonging to the same group as the homohexameric LAPs from mammals. Protein blots showed low constitutive expression of the LAP in all organs of potato plants: buds, flowers, tubers, roots and leaves. An increase in steady-state protein that was paralleled by an increase in total LAP activity was observed in leaf extracts after supplying jasmonic acid via the petioles. Plants containing the cDNA in antisense orientation behind the constitutive Cauliflower Mosaic Virus 35S promoter showed nearly complete reduction of the corresponding mRNA in leaves. However, in these plants LAP activities were only decreased by about 20% as compared to non-transgenic potato plants, while after feeding with jasmonic acid the activity of transgenic plants was reduced to about 5% of that of non-transgenic plants also induced by jasmonic acid. There was no phenotypic difference between wild-type and LAP antisense plants.

Amino Acid Sequence↗
PubMed1992

General roles of abscisic and jasmonic acids in gene activation as a result of mechanical wounding.

Exogenous application of abscisic acid (ABA) has been shown to induce a systemic pattern of proteinase inhibitor II (pin2) mRNA accumulation identical to that induced by mechanical wounding. Evidence is presented that the ABA-specific response is not restricted to pin2 genes but appears to be part of a general reaction to wound stress. Four other wound-induced, ABA-responsive genes that encode two additional proteinase inhibitors, the proteolytic enzyme leucine aminopeptidase, and the biosynthetic enzyme threonine deaminase were isolated from potato plants. Wounding or treatment with ABA resulted in a pattern of accumulation of these mRNAs very similar to that of pin2. ABA-deficient plants did not accumulate any of the mRNAs upon wounding, although they showed normal levels of expression upon ABA treatment. Also, application of methyl jasmonate (MeJA) induced a strong accumulation of these transcripts, both in wild-type and in ABA-deficient plants, thus supporting a role for jasmonic acid as an intermediate in the signaling pathway that leads from ABA accumulation in response to wounding to the transcriptional activation of the genes.

Abscisic Acid↗
PubMed1991

Repression of the CaMV 35S promoter by the octopine synthase enhancer element.

A 16 base-pair palindrome upstream of the Agrobacterium tumefaciens octopine synthase (ocs) gene functions as a positive regulatory element in plant cells (Ellis et al. (1987) EMBO J. 6, 3203-3208; Fromm et al. (1989) Plant Cell 1, 977-984). We have converted it into a negative element by locating two copies flanking the TATA-box of the constitutively expressed CaMV 35S promoter. The reduced promoter activity is very likely due to sterical hindrance of the ocs binding protein (OCSTF) x ocs complex with the transcription initiation complex. We propose that this type of constructs can be used for the identification of recognition sites for DNA-binding proteins which are labile in vitro as well as for determining the DNA-binding activity of a trans-acting factor in vivo.

Amino Acid Oxidoreductases↗
PubMed1990

Gene expression during tuber development in potato plants.

Potato tubers are modified stems that have differentiated into storage organs. Factors such as day-length, nitrogen supply, and levels of the phytohormones cytokinin and gibberellic acid, are known to control tuberization. Morphological changes during tuber initiation are accompanied by the accumulation of a characteristic set of proteins, thought to be involved in N-storage (i.e. patatin) or defense against microbial or insect attack (i.e. proteinase inhibitor II). Additionally, deposition of large amounts of starch occurs during tuber formation, which is paralleled by an increase in sucrose synthase and other enzymes involved in starch biosynthesis (i.e. ADP-glucose pyrophosphorylase, starch synthases, and branching enzyme). Potential controlling mechanisms for genes expressed during tuberization are discussed.

Carboxylic Ester Hydrolases↗
PubMed1990

cis regulatory elements directing tuber-specific and sucrose-inducible expression of a chimeric class I patatin promoter/GUS-gene fusion.

The 5'-upstream region of the class I patatin gene B33 directs strong expression of the beta-glucuronidase (GUS) reporter gene in potato tubers and in leaves treated with sucrose. Cis-acting elements affecting specificity and level of expression were identified by deletion analysis in transgenic potato plants. A putative tuber-specific element is located downstream from position -195. Nuclear proteins present in leaf and tuber extracts bind specifically to a conserved AT rich motif within this region. A DNA fragment between -183 and -143, including the binding site is, however, not able to enhance the expression of a truncated 35S promoter from cauliflower mosaic virus. Independent positive elements contributing to a 100-fold increase relative to the basic tuber-specific element are located between -228 and -195; -736 and -509, -930 and -736 and -1512 and -951. Sucrose inducibility is controlled by sequences downstream of position -228, indicating that the tuber-specific and sucrose-inducible elements are in close proximity.

Binding Sites↗
PubMed1990

Identification of potato nuclear proteins binding to the distal promoter region of the proteinase inhibitor II gene.

Potato nuclear proteins specifically bind to a DNA sequence at the most 5' distal region of the promoter of a potato proteinase inhibitor II gene. Binding studies using the electrophoretic mobility-shift assay showed the appearance of two protein-DNA complexes in the presence of both tuber and leaf nuclear protein extracts. Mechanical wounding of the leaves had no effect on the amount of specific protein-DNA complexes formed. DNase I protection analysis and binding to synthetic oligonucleotides identified the sequence 5'-GAGGGTATTTTCGTAA-3' as the target for the noncooperative binding of two potato nuclear proteins to the upstream element. Methylation interference experiments showed that guanine nucleotides separated by one turn of the DNA helix were in close contact with the proteins. The binding ability of a series of mutated synthetic oligonucleotides further defined the sequence requirements for protein binding, which appeared to contact one side of the DNA helix.

Base Sequence↗
PubMed1990

Aseptic necrosis of the sternal end of the clavicle Friedrich's disease.

A case of aseptic necrosis of the medial segment of the clavicle with X-ray images of fragmentation and few clinical symptoms is presented. This condition develops spontaneously and leads to early sternoclavicular osteoarthritis. The benign nature of the disease and the absence of treatment make it important to establish the correct diagnosis, differentiating it from other disorders in this area.

Adolescent↗
PubMed1989

Nuclear proteins binding to a cauliflower mosaic virus 35S truncated promoter.

Proteins present in tobacco nuclear extracts bind to a truncated cauliflower mosaic virus (CaMV) 35S promoter fragment (from -90 to +2 relative to the transcription start site) in a sequence specific manner. Gel mobility shift assays show the presence of two protein-DNA complexes that are not competed by a -47/+2 promoter fragment. DNAse I protection and DNA methylation interference reveal two protected sites in the slower migrating complex; both include the pentamer TGACG, separated by a stretch of eight nucleotides where G methylation does not prevent the binding of the proteins. The faster complex is the prevalent form at low protein concentrations. As the protein concentration increases a non-linear rise in the amount of the slower migrating complex relative to the faster one is seen suggesting that cooperative effects are involved in the binding to the second site.

Base Sequence↗
PubMed1989

Abscisic acid is involved in the wound-induced expression of the proteinase inhibitor II gene in potato and tomato.

Plants respond to wounding or pathogen attack by a variety of biochemical reactions, involving in some instances gene activation in tissues far apart from the actual site of wounding or pathogen invasion. One of the best analyzed examples for such a systemic reaction is the wound-induced expression of proteinase inhibitor genes in tomato and potato leaves. Local wounding of potato or tomato plants results in the accumulation of proteinase inhibitors I and II throughout the aerial part of the plant. In contrast to wild-type plants, abscisic acid-deficient mutants of potato (droopy) and tomato (sit) show a drastically reduced induction of these genes in response to plant wounding. High levels of proteinase inhibitor II gene expression are obtained in mutant and wild-type plants upon exogenous application of abscisic acid. Measurements of the endogenous abscisic acid levels in wild-type plants show that wounding results in increased levels of this phytohormone in wounded and nonwounded systemically induced leaves. Thus these results show that the plant hormone abscisic acid is involved in the wound-induced activation of the proteinase inhibitor II gene. Furthermore, they are compatible with a model assuming this hormone to be the actual mediator of the systemic wound response.

Journal Article↗
PubMed1987

Multiple variability in the sequence of a family of maize endosperm proteins.

A collection of cDNA clones, corresponding to a group of maize endosperm proteins classified in the glutelin-2 (or reduced soluble proteins) and in the zein-2 subfractions, has been identified and characterized. The nucleotide sequence of three of these clones has been obtained and the amino acid sequence deduced. They appear to correspond to a small family of genes that are specifically expressed in immature endosperm simultaneously to zeins, the best characterized proteins from this tissue. Unlike zeins, the proteins of the glutelin-2 and zein-2 family contain sequences homologous to storage proteins from other cereals such as gliadins or hordeins. The cDNA clones encoding for the two types of proteins have been compared, and a high degree of homology has been observed for both the nucleotide and amino acid sequences. The differences existing in both the coding and non-coding regions allow the definition of multiple types of variability in their sequence. An hypothesis is proposed on how sequence diversity may have been generated in this particular class of plant proteins.

Amino Acid Sequence↗
PubMed1985

Nucleic acid (cDNA) and amino acid sequences of the maize endosperm protein glutelin-2.

The cDNA coding for a glutelin-2 protein from maize endosperm has been cloned and the complete amino acid sequence of the protein derived for the first time. An immature maize endosperm cDNA bank was screened for the expression of a beta-lactamase:glutelin-2 (G2) fusion polypeptide by using antibodies against the purified 28 kd G2 protein. A clone corresponding to the 28 kd G2 protein was sequenced and the primary structure of this protein was derived. Five regions can be defined in the protein sequence: an 11 residue N-terminal part, a repeated region formed by eight units of the sequence Pro-Pro-Pro-Val-His-Leu, an alternating Pro-X stretch 21 residues long, a Cys rich domain and a C-terminal part rich in Gln. The protein sequence is preceded by 19 residues which have the characteristics of the signal peptide found in secreted proteins. Unlike zeins, the main maize storage proteins, 28 kd glutelin-2 has several homologous sequences in common with other cereal storage proteins.

Amino Acid Sequence↗
PubMedDate not supplied

Hepatitis B virus replication in acute hepatitis B, acute hepatitis B virus-hepatitis delta virus coinfection and acute hepatitis delta superinfection.

To evaluate the effect of hepatitis delta virus on the level of replication of hepatitis B virus and to assess the clinical significance that such an effect might have on the final outcome of the infection, the serological profile of hepatitis B virus DNA was investigated in 153 patients with acute or chronic hepatitis B virus infection with or without associated delta infection. Serum hepatitis B virus DNA was detected in 57% of patients with acute hepatitis B, 67% of those with acute hepatitis B virus-hepatitis delta virus coinfection and 25% of HBsAg carriers with hepatitis delta virus superinfection during the first week after the onset of symptoms. Patients with acute hepatitis B and those with acute hepatitis B virus-hepatitis delta virus coinfection did not differ significantly with respect to the serological profile of hepatitis B virus DNA and final clinical outcome. Within the group of HBsAg carriers with hepatitis delta virus superinfection, all patients who were initially negative for hepatitis B virus DNA developed chronic hepatitis delta virus infection, whereas 3 of the 4 patients with active hepatitis B virus infection at the time of superinfection showed transient inhibition of hepatitis B virus replication followed by termination of hepatitis delta virus infection in two patients. Therefore, although delta virus may inhibit the replication of hepatitis B virus among chronic HBsAg carriers, this effect is not readily apparent among patients with hepatitis B virus-hepatitis delta virus coinfection.

Acute Disease↗
PubMedDate not supplied

[The arterial complications of closed injuries to the shoulder girdle].

After a period of time of 5 years, we made a review of all the patients registered at our Center. Eight cases of closed traumatism at the scapulohumeral belt, with vascular injury associated (0.2% of all closed traumatisms at this level registered in our center during this time) were reported. Six patients presented also an osteoarticular injury associated. Three different vascular injuries were showed: three cases of complete arterial section, two arterial contusions and a partial arterial section. From the two cases without osteoarticular injuries, one of them showed a complete section and the other presented an arterial contusion. Polytraumatic patients showed multiple osteoarticular injuries. We registered one fracture-luxation at the shoulder, 3 diafisaric humeral fractures, one humeral neck fracture, one clavicle fracture, one fracture-luxation at the cervical column and one simple luxation of the shoulder.

Adult↗
PubMedDate not supplied

[Vascular injuries of the lower extremity].

Authors present their experience (32 patients affected by a traumatic femoropopliteal injury) with vascular traumatisms at the lower limb. Causes, treatment and successful results with the new technics and the early clinical management to the patients are commented.

Adolescent↗