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E Villalobos

Publications and source records attributed to E Villalobos.

At least 19 recordsLinked to original sources
PubMed2006

Immunogold localization of trehalose-6-phosphate synthase in leaf segments of wild-type and transgenic tobacco plants expressing the AtTPS1 gene from Arabidopsis thaliana.

Following the establishment of a transgenic line of tobacco (B5H) expressing the trehalose-6-phosphate synthase (TPS) gene from Arabidopsis thaliana, a preliminary immunolocalization study was conducted using leaves of adequately watered B5H and wild-type plants. Immunocytochemical staining, followed by electron microscopy showed that the enzyme could be detected in both B5H and wild-type plants at two different levels. Quantification showed the signal to be two to three times higher in transgenic plants than in the wild type. This enzyme was markedly present in the vacuoles and the cell wall, and to a lesser extent in the cytosol. Moreover, a high profusion of gold particles was detected in adjacent cells and in the sieve elements. Occasional spots were also detected in chloroplasts and the nucleus, especially in the transgenic B5H line. No labeling signal was detected in mitochondria. Protein localization seems to confirm the important role of TPS in sugar metabolism and transport through the plant, which could explain its role in plant stress tolerance. Finally, it can be expected that TPS from tobacco has a relatively high similarity to the TPS of Arabidopsis thaliana.

Arabidopsis↗
PubMed2004

Molecular cloning and characterization of a maize transglutaminase complementary DNA.

Two related complementary DNA clones, TGZ15 and TGZ21, encoding active maize transglutaminase (TGase) have been isolated for the first time in plants by molecular cloning (Patent Pending PCT/ES03/00247). Southern and northern blot analyses indicate that the two cDNAs probably corresponded to two different single-copy genes in the maize genome. Northern blot analyses revealed that the transcript is expressed preferentially in young leaves and differentiated embryogenic maize callus. This expression is dependent on light exposure time. TGase activity of the proteins encoded by clones TGZ15 and TGZ21 was detected in bacterial extracts overexpressing them, using two enzymatic assays. TGase activity was significantly higher than that of the empty-phagemid bacterial extracts. As in other TGases, this activity was inhibited by monodansyl cadaverine (MDC), GTP and the absence of exogenous Ca(2+). Likewise, light-stimulated Ca(2+)-dependent TGase activity was detected in thylakoids and grana of maize chloroplast, which was inhibited by MDC, GTP, DIECA and Diuron.

Amino Acid Sequence↗
PubMed2001

Immunogold localization of a transglutaminase related to grana development in different maize cell types.

A comparative study of the subcellular localization of a plant transglutaminase (TGase; EC 2.3.2.13) in various in vivo and in vitro maize cell types was carried out with a polyclonal antibody raised against a 58 kDa TGase purified from Helianthus tuberosus leaves. Immunocytochemical staining, followed by electron microscopy, showed that this enzyme was markedly present in the grana-appressed thylakoids of mature chloroplasts of the light-exposed cells. Moreover, during embryogenic callus chloroplast differentiation, the abundance of TGase in the grana-appressed thylakoids depended on the degree of grana development and was greater than in mature leaf chloroplasts. In addition to the 58 kDa form, two other forms of the protein (of 77 and 34 kDa) were obtained by Western blot. The 77 kDa form might correspond to the inactive form and was immunodetected in dense vesicles observed in dark-grown embryogenic callus cells. In adult leaves, the enzyme was also markedly present in the grana-appressed thylakoids of the mesophyll cell chloroplasts, though very scarce and dispersed in the bundle-sheath cell chloroplasts (which do not contain grana). The concordance of these localizations with those described for the light-harvesting antenna proteins of the photosystem II suggests that it is possible that this TGase has a functional role in photosynthesis, perhaps modulating the photosynthetic efficiency and the absorption of excess light by means of polyamine conjugation to the antenna proteins.

Immunoblotting↗
PubMed1992

[Acute lymphoblastic leukemias off therapy: course of 80 cases after treatment cessation].

PURPOSE: To retrospectively analyse all the patients diagnosed and treated in the same hospital for acute lymphoblastic leukaemia (ALL) in whom therapy was suppressed after sustained complete remission (CR) for a variable period. PATIENTS AND METHODS: Eighty cases of ALL treated at the Jiménez Díaz Foundation between 1968 and 1991 were revised. Treatment had been suppressed after 60 months of maintained CR (1968-1974) or after 28 months (1986-1991), with a median follow-up after suppression of 6 years. All the patients had been treated with several protocols (FJD-68, FJD/BFM, APO, BFM-83, BFM-86 and BFM-90). Maintained CR, relapses and course after therapy cessation were analysed. Actuarial curves of RC duration and survival were drawn according to the Cutler and Ederer life tables. RESULTS: The age at diagnosis ranged from 1.5 to 68 years. Childhood (< 15 years) ALL presented in 49 cases; 25 were young adults (15-30 years), and 6 others were over 30 years of age. Two of the 80 patients (2.5%) died in CR (astrocytoma and demyelinating leukoencephalopathy). Fifty-eight patients (72.5%) are living in maintained CR; 20 others relapsed (25%), 14 of them (70%) attaining a second CR. Allogenic BMT was carried out in 4 such cases. Four patients are out of any treatment after the second CR. The actuarial curves of CR duration after suppression of therapy gave a stable plateau at 73% for children, at 75% for young adults and at 22% for patients over 30 years. The survival after suppression of therapy showed a plateau at 75% for children and at 86% for young adults. CONCLUSIONS: 1) Relapse was seen in 25% of the patients after cessation of therapy. 2) Relapse occurred in the first two years after therapy cessation in 75% of the instances. 3) At this writing, 78.7% of the patients keep up the CR. 4) Adults over 30 years of age comprise the poorest prognosis. 5) The course of young adults in this series after cessation of therapy is as good as that of children.

Adolescent↗
PubMed1989

[Possibilities of remission of acute lymphoblastic leukemia in adults: retrospective study of 51 patients subjected to a "total therapy" protocol in the period 1969-1983].

Between 1969 and 1983, 51 (35 men and 16 women) new cases of acute lymphoblastic leukemia (ALL) were diagnosed in patients aged 15 to 85 years (mean 21 yrs.). All patients received a "total therapy" which included: 1st induction (PRD, VCR, DBR, and/or L-ASN); 2nd, Central Nervous System profilaxis (craneal TCT and/or intrathecal MTx); 3rd, maintenance (6MP and MTx) and 4th, reinductions every 3 months (PRD, VCR, and DRB). This treatment lasted for at least 3 years. Complete Remission (CR) was achieved in 45 patients (88.2%): 3 of these patients were referred to other centers to continue treatment, 1 patient developed an early "metamorphosis" to hemophagocytic hystiocytosis and another patient developed a late chronic granulocytic leukemia (Ph +) dying a few months later after an acute myeloblastic worsening. During treatment 16 patients relapsed (9 in bone marrow and 7 in Central Nervous System). Treatment was discontinued in 24 patients with complete remission of which 5 relapsed in bone marrow 17 to 61 months after treatment). In one of the latter (ALL Ph +) an allogenic bone marrow transplant was performed and CR was achieved and maintained 46 months later. The post diagnosis acutarial curve of the 51 patients gave a mean survival of 6 years with a plateau at 43% of the patients after 11 years. The duration of the first uninterrupted CR was of 6.5 years and a plateau was reached at 46% of the patients after 10.5 years. At the present time, 20 patients are in CR (46 to 129 months) without treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1985

Acute lymphoblastic leukaemia in adults: results of a 'total-therapy' programme in 47 patients over 15 years old.

For the last 13 years, 47 patients with ALL over 15 years old (range 15-72; median 21) entered a 'total-therapy' programme. All cases received a 6-8 week induction course of PRD, VCR, DRB and/or L-ASN. Prophylaxis of CNS was done by cranial radiotherapy plus i.t. MTX in 32/45 patients who attained complete remission (CR). After CR, subsequent therapy involved a programme of maintenance with 6MP and MTX at full doses. Pulses of intermittent reinforcement (PRD, VCR and DRB) were done for 2 weeks, every 3 months, for at least 3 years. CR was achieved in 42/47 patients (89.3%). The median relapse-free survival of the patients who attained CR was 57 months, with an 8-year estimated disease-free survival rate of 43% for those cases. If actuarial assumptions were to be sustained, it would indicate an encouraging cure rate of 38% of all our adult ALL patients (mainly in those cases between 15 and 30 years old).

Adolescent↗