gonzalo zerpa - Academia.edu (original) (raw)

Papers by gonzalo zerpa

Research paper thumbnail of Selección y propagación de árboles superiores de Eucaliptus - grandis y E- grandis x urophylla en la Finca Deforsa, San Carlos, Estado Cojedes / Gonzalo D'J. Carrero Zerpa

Mecanografiado Informe de pasantía (Ing. Forestal)-- Universidad de Los Andes, Facultad de Cienci... more Mecanografiado Informe de pasantía (Ing. Forestal)-- Universidad de Los Andes, Facultad de Ciencias Forestales y Ambientales, Escuela de Ingeniería Forestal, Mérida, 1996 Incluye bibliografía

Research paper thumbnail of Alternative splicing prevents transferrin secretion during differentiation of a human oligodendrocyte cell line

Journal of Neuroscience Research, 2000

Transferrin, the iron-transport protein of vertebrate serum, is synthesized mainly in the liver, ... more Transferrin, the iron-transport protein of vertebrate serum, is synthesized mainly in the liver, from which it is secreted into the blood. Transferrin is also synthesized in oligodendrocytes and is an early marker of their differentiation. We have analyzed the regulation of transferrin expression in HOG cells, a human oligodendrocyte cell line. Transferrin expression was correlated with the appearance of oligodendrocyte differentiation markers when cells were exposed to differentiation medium. In contrast to the protein expressed in hepatocytes or in Sertoli cells, transferrin was secreted by neither HOG cells nor immature rat primary oligodendrocytes in vitro. Moreover, transferrin appears to be localized in the cytosol and not in the secretory compartment, as is expected for secreted proteins. This transferrin localization was correlated with the synthesis of a specific transcript, resulting from an alternative splicing, which leads to the elimination of the signal peptide sequence. These results suggest the existence of a functional difference between transferrin synthesized in the brain and in other organs such as liver and testis. They are in accordance with the hypothesis that transferrin plays a specific role, other than iron transport, in oligodendrocyte maturation and in the myelination process.

Research paper thumbnail of Myelination and motor coordination are increased in transferrin transgenic mice

Journal of Neuroscience Research, 2003

Research paper thumbnail of Light Exposue Activates Retina Ganglion Cell Lysophosphatidic Acid Acyl Transferase and Phosphatidic Acid Phosphatase by a c-fos-Dependent Mechanism

Journal of Neurochemistry, 2001

... Zerpa, GA d. A., Guido, ME, Bussolino, DF, Pasquare, SJ, Castagnet, PI, Giusto, NM and Caputt... more ... Zerpa, GA d. A., Guido, ME, Bussolino, DF, Pasquare, SJ, Castagnet, PI, Giusto, NM and Caputto, BL (1999 ... 1,2-diacyl-[2-3 H]glycerol from [ 3 H]PA as described by Pasquaré and Giusto ... 16 Gomez Muñoz A., Hatch GM, Martin A., Jamal Z., Vance DE, Brindley DN (1992 b) Effects ...

Research paper thumbnail of Light affects c-fos expression and phospholipid synthesis in both retinal ganglion cells and photoreceptor cells in an opposite way for each cell type

Molecular Brain Research, 1998

Retina photoreceptor and ganglion cells isolated from chicks that in vivo were exposed to light h... more Retina photoreceptor and ganglion cells isolated from chicks that in vivo were exposed to light have a different phospholipid labeling Ž capacity than those from chicks in the dark. In the light exposed animals, the phospholipid labeling in the ganglion cells is higher D% 45,. p-0.005 than in those maintained in the dark, whereas in the photoreceptor cells, the opposite occurs, that is, the phospholipid labeling is higher in the dark than in light. The light-dark differences for phospholipid labeling correlate with the expression of c-fos: when c-fos Ž. expression increases both in mRNA and in c-Fos protein content , phospholipid labeling increases concomitantly. That is, in ganglion cells, c-fos expression and the phospholipid synthesis is higher in light with respect to dark, whereas in photoreceptor cells, c-fos expression and phospholipid synthesis is higher in dark with respect to light. Moreover, when an oligonucleotide antisense to c-fos is administered intraocularly prior to separating the animals into light and dark, no differences in c-fos expression and, consequently, no differences in phospholipid synthesis are found between animals in light and dark. Taken together, these results point to a novel mechanism by which rapid genomic responses to cell stimulation are converted to longer lasting changes in the cell components.

Research paper thumbnail of Alternative Splicing in the Brain of Mice and Rats Generates Transferrin Transcripts Lacking, as in Humans, the Signal Peptide Sequence

Transferrin (Tf), the iron-transport protein of vertebrate serum, is mainly synthesized in hepato... more Transferrin (Tf), the iron-transport protein of vertebrate serum, is mainly synthesized in hepatocytes but is also found in other cell-types including oligodendrocytes. Our laboratory has characterized in a human oligodendrial cell line the presence of a new Tf transcript containing an alternative exon 1b replacing the classical exon 1 and conducting to the elimination of the signal peptide sequence. In this manuscript, we show by RT-PCR and 5'-RACE experiments that alternative transcripts also exist in mouse and rat and are found in brain mRNA preparations. Mouse alternative first exon is homologous to human exon 1b while rat Tf gene was found to use a new first exon named 1c. In all species, the alternative transcript does not contain the signal peptide sequence and possibly encode for a Tf protein devoid of signal peptide showing that this phenomenon is not restricted to human gene. We also present genomic sequence data from the previously unknown 5' genomic rat region, which allowed the alignment of the alternative exons 1 in the three species.

Research paper thumbnail of Selección y propagación de árboles superiores de Eucaliptus - grandis y E- grandis x urophylla en la Finca Deforsa, San Carlos, Estado Cojedes / Gonzalo D'J. Carrero Zerpa

Mecanografiado Informe de pasantía (Ing. Forestal)-- Universidad de Los Andes, Facultad de Cienci... more Mecanografiado Informe de pasantía (Ing. Forestal)-- Universidad de Los Andes, Facultad de Ciencias Forestales y Ambientales, Escuela de Ingeniería Forestal, Mérida, 1996 Incluye bibliografía

Research paper thumbnail of Alternative splicing prevents transferrin secretion during differentiation of a human oligodendrocyte cell line

Journal of Neuroscience Research, 2000

Transferrin, the iron-transport protein of vertebrate serum, is synthesized mainly in the liver, ... more Transferrin, the iron-transport protein of vertebrate serum, is synthesized mainly in the liver, from which it is secreted into the blood. Transferrin is also synthesized in oligodendrocytes and is an early marker of their differentiation. We have analyzed the regulation of transferrin expression in HOG cells, a human oligodendrocyte cell line. Transferrin expression was correlated with the appearance of oligodendrocyte differentiation markers when cells were exposed to differentiation medium. In contrast to the protein expressed in hepatocytes or in Sertoli cells, transferrin was secreted by neither HOG cells nor immature rat primary oligodendrocytes in vitro. Moreover, transferrin appears to be localized in the cytosol and not in the secretory compartment, as is expected for secreted proteins. This transferrin localization was correlated with the synthesis of a specific transcript, resulting from an alternative splicing, which leads to the elimination of the signal peptide sequence. These results suggest the existence of a functional difference between transferrin synthesized in the brain and in other organs such as liver and testis. They are in accordance with the hypothesis that transferrin plays a specific role, other than iron transport, in oligodendrocyte maturation and in the myelination process.

Research paper thumbnail of Myelination and motor coordination are increased in transferrin transgenic mice

Journal of Neuroscience Research, 2003

Research paper thumbnail of Light Exposue Activates Retina Ganglion Cell Lysophosphatidic Acid Acyl Transferase and Phosphatidic Acid Phosphatase by a c-fos-Dependent Mechanism

Journal of Neurochemistry, 2001

... Zerpa, GA d. A., Guido, ME, Bussolino, DF, Pasquare, SJ, Castagnet, PI, Giusto, NM and Caputt... more ... Zerpa, GA d. A., Guido, ME, Bussolino, DF, Pasquare, SJ, Castagnet, PI, Giusto, NM and Caputto, BL (1999 ... 1,2-diacyl-[2-3 H]glycerol from [ 3 H]PA as described by Pasquaré and Giusto ... 16 Gomez Muñoz A., Hatch GM, Martin A., Jamal Z., Vance DE, Brindley DN (1992 b) Effects ...

Research paper thumbnail of Light affects c-fos expression and phospholipid synthesis in both retinal ganglion cells and photoreceptor cells in an opposite way for each cell type

Molecular Brain Research, 1998

Retina photoreceptor and ganglion cells isolated from chicks that in vivo were exposed to light h... more Retina photoreceptor and ganglion cells isolated from chicks that in vivo were exposed to light have a different phospholipid labeling Ž capacity than those from chicks in the dark. In the light exposed animals, the phospholipid labeling in the ganglion cells is higher D% 45,. p-0.005 than in those maintained in the dark, whereas in the photoreceptor cells, the opposite occurs, that is, the phospholipid labeling is higher in the dark than in light. The light-dark differences for phospholipid labeling correlate with the expression of c-fos: when c-fos Ž. expression increases both in mRNA and in c-Fos protein content , phospholipid labeling increases concomitantly. That is, in ganglion cells, c-fos expression and the phospholipid synthesis is higher in light with respect to dark, whereas in photoreceptor cells, c-fos expression and phospholipid synthesis is higher in dark with respect to light. Moreover, when an oligonucleotide antisense to c-fos is administered intraocularly prior to separating the animals into light and dark, no differences in c-fos expression and, consequently, no differences in phospholipid synthesis are found between animals in light and dark. Taken together, these results point to a novel mechanism by which rapid genomic responses to cell stimulation are converted to longer lasting changes in the cell components.

Research paper thumbnail of Alternative Splicing in the Brain of Mice and Rats Generates Transferrin Transcripts Lacking, as in Humans, the Signal Peptide Sequence

Transferrin (Tf), the iron-transport protein of vertebrate serum, is mainly synthesized in hepato... more Transferrin (Tf), the iron-transport protein of vertebrate serum, is mainly synthesized in hepatocytes but is also found in other cell-types including oligodendrocytes. Our laboratory has characterized in a human oligodendrial cell line the presence of a new Tf transcript containing an alternative exon 1b replacing the classical exon 1 and conducting to the elimination of the signal peptide sequence. In this manuscript, we show by RT-PCR and 5'-RACE experiments that alternative transcripts also exist in mouse and rat and are found in brain mRNA preparations. Mouse alternative first exon is homologous to human exon 1b while rat Tf gene was found to use a new first exon named 1c. In all species, the alternative transcript does not contain the signal peptide sequence and possibly encode for a Tf protein devoid of signal peptide showing that this phenomenon is not restricted to human gene. We also present genomic sequence data from the previously unknown 5' genomic rat region, which allowed the alignment of the alternative exons 1 in the three species.