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Papers by Berenice Alfonso

Research paper thumbnail of gcm2 Promotes Glial Cell Differentiation and Is Required with glial cells missing for Macrophage Development in Drosophila

Developmental Biology, Aug 1, 2002

glial cells missing (gcm) is the primary regulator of glial cell fate in Drosophila. In addition,... more glial cells missing (gcm) is the primary regulator of glial cell fate in Drosophila. In addition, gcm has a role in the differentiation of the plasmatocyte/macrophage lineage of hemocytes. Since mutation of gcm causes only a decrease in plasmatocyte numbers without changing their ability to convert into macrophages, gcm cannot be the sole determinant of plasmatocyte/macrophage differentiation. We have characterized a gcm homolog, gcm2. gcm2 is expressed at low levels in glial cells and hemocyte precursors. We show that gcm2 has redundant functions with gcm and has a minor role promoting glial cell differentiation. More significant, like gcm, mutation of gcm2 leads to reduced plasmatocyte numbers. A deletion removing both genes has allowed us to clarify the role of these redundant genes in plasmatocyte development. Animals deficient for both gcm and gcm2 fail to express the macrophage receptor Croquemort. Plasmatocytes are reduced in number, but still express the early marker Peroxidasin. These Peroxidasin-expressing hemocytes fail to migrate to their normal locations and do not complete their conversion into macrophages. Our results suggest that both gcm and gcm2 are required together for the proliferation of plasmatocyte precursors, the expression of Croquemort protein, and the ability of plasmatocytes to convert into macrophages.

Research paper thumbnail of Cell Migration along the Lateral Cortical Stream to the Developing Basal Telencephalic Limbic System

Journal of Neuroscience, 2006

Research paper thumbnail of gcm2 Promotes Glial Cell Differentiation and Is Required with glial cells missing for Macrophage Development in Drosophila

Developmental Biology, 2002

Research paper thumbnail of Epistatic and functional interactions of catecholo-methyltransferase

Background: Neuregulin1 (NRG1)-ErbB signaling has been implicated in the pathogenesis of cancer a... more Background: Neuregulin1 (NRG1)-ErbB signaling has been implicated in the pathogenesis of cancer and schizophrenia. We have previously reported that NRG1-stimulated migration of B lymphoblasts is PI3K-AKT1dependent and impaired in patients with schizophrenia and significantly linked to the catechol-o-methyltransferase (COMT) Val108/158Met functional polymorphism. Methodology/Principal Findings: We have now examined AKT1 activation in NRG1-stimulated B lymphoblasts and other cell models and explored a functional relationship between COMT and AKT1. NRG1-induced AKT1 phosphorylation was significantly diminished in Val carriers compared to Met carriers in both normal subjects and in patients. Further, there was a significant epistatic interaction between a putatively functional coding SNP in AKT1 (rs1130233) and COMT Val108/158Met genotype on AKT1 phosphorylation. NRG1 induced translocation of AKT1 to the plasma membrane also was impaired in Val carriers, while PIP3 levels were not decre...

Research paper thumbnail of Polymerase Driven Nesa

Research paper thumbnail of Exonuclease Cycling Assay

Research paper thumbnail of Epistatic and Functional Interactions of Catechol-O-Methyltransferase (COMT) and AKT1 on Neuregulin1-ErbB Signaling in Cell Models

PLoS ONE, 2010

Background: Neuregulin1 (NRG1)-ErbB signaling has been implicated in the pathogenesis of cancer a... more Background: Neuregulin1 (NRG1)-ErbB signaling has been implicated in the pathogenesis of cancer and schizophrenia. We have previously reported that NRG1-stimulated migration of B lymphoblasts is PI3K-AKT1dependent and impaired in patients with schizophrenia and significantly linked to the catechol-o-methyltransferase (COMT) Val108/158Met functional polymorphism.

Research paper thumbnail of Novel Cassette-Based Shuttle Vector System for Gram-Positive Bacteria

Applied and Environmental Microbiology, 2004

Our understanding of staphylococcal pathogenesis depends on reliable genetic tools for gene expre... more Our understanding of staphylococcal pathogenesis depends on reliable genetic tools for gene expression analysis and tracing of bacteria. Here, we have developed and evaluated a series of novel versatile Escherichia coli-staphylococcal shuttle vectors based on PCR-generated interchangeable cassettes. Advantages of our module system include the use of (i) staphylococcal low-copy-number, high-copy-number, thermosensitive and theta replicons and selectable markers (choice of erythromycin, tetracycline, chloramphenicol, kanamycin, or spectinomycin); (ii) an E. coli replicon and selectable marker (ampicillin); and (iii) a staphylococcal phage fragment that allows high-frequency transduction and an SaPI fragment that allows site-specific integration into the Staphylococcus aureus chromosome. The staphylococcal cadmium-inducible P cad -cadC and constitutive P blaZ promoters were designed and analyzed in transcriptional fusions to the staphylococcal ␤-lactamase blaZ, the Vibrio fischeri luxAB, and the Aequorea victoria green fluorescent protein reporter genes. The modular design of the vector system provides great flexibility and variety. Questions about gene dosage, complementation, and cis-trans effects can now be conveniently addressed, so that this system constitutes an effective tool for studying gene regulation of staphylococci in various ecosystems.

Research paper thumbnail of gcm2 Promotes Glial Cell Differentiation and Is Required with glial cells missing for Macrophage Development in Drosophila

Developmental Biology, Aug 1, 2002

glial cells missing (gcm) is the primary regulator of glial cell fate in Drosophila. In addition,... more glial cells missing (gcm) is the primary regulator of glial cell fate in Drosophila. In addition, gcm has a role in the differentiation of the plasmatocyte/macrophage lineage of hemocytes. Since mutation of gcm causes only a decrease in plasmatocyte numbers without changing their ability to convert into macrophages, gcm cannot be the sole determinant of plasmatocyte/macrophage differentiation. We have characterized a gcm homolog, gcm2. gcm2 is expressed at low levels in glial cells and hemocyte precursors. We show that gcm2 has redundant functions with gcm and has a minor role promoting glial cell differentiation. More significant, like gcm, mutation of gcm2 leads to reduced plasmatocyte numbers. A deletion removing both genes has allowed us to clarify the role of these redundant genes in plasmatocyte development. Animals deficient for both gcm and gcm2 fail to express the macrophage receptor Croquemort. Plasmatocytes are reduced in number, but still express the early marker Peroxidasin. These Peroxidasin-expressing hemocytes fail to migrate to their normal locations and do not complete their conversion into macrophages. Our results suggest that both gcm and gcm2 are required together for the proliferation of plasmatocyte precursors, the expression of Croquemort protein, and the ability of plasmatocytes to convert into macrophages.

Research paper thumbnail of Cell Migration along the Lateral Cortical Stream to the Developing Basal Telencephalic Limbic System

Journal of Neuroscience, 2006

Research paper thumbnail of gcm2 Promotes Glial Cell Differentiation and Is Required with glial cells missing for Macrophage Development in Drosophila

Developmental Biology, 2002

Research paper thumbnail of Epistatic and functional interactions of catecholo-methyltransferase

Background: Neuregulin1 (NRG1)-ErbB signaling has been implicated in the pathogenesis of cancer a... more Background: Neuregulin1 (NRG1)-ErbB signaling has been implicated in the pathogenesis of cancer and schizophrenia. We have previously reported that NRG1-stimulated migration of B lymphoblasts is PI3K-AKT1dependent and impaired in patients with schizophrenia and significantly linked to the catechol-o-methyltransferase (COMT) Val108/158Met functional polymorphism. Methodology/Principal Findings: We have now examined AKT1 activation in NRG1-stimulated B lymphoblasts and other cell models and explored a functional relationship between COMT and AKT1. NRG1-induced AKT1 phosphorylation was significantly diminished in Val carriers compared to Met carriers in both normal subjects and in patients. Further, there was a significant epistatic interaction between a putatively functional coding SNP in AKT1 (rs1130233) and COMT Val108/158Met genotype on AKT1 phosphorylation. NRG1 induced translocation of AKT1 to the plasma membrane also was impaired in Val carriers, while PIP3 levels were not decre...

Research paper thumbnail of Polymerase Driven Nesa

Research paper thumbnail of Exonuclease Cycling Assay

Research paper thumbnail of Epistatic and Functional Interactions of Catechol-O-Methyltransferase (COMT) and AKT1 on Neuregulin1-ErbB Signaling in Cell Models

PLoS ONE, 2010

Background: Neuregulin1 (NRG1)-ErbB signaling has been implicated in the pathogenesis of cancer a... more Background: Neuregulin1 (NRG1)-ErbB signaling has been implicated in the pathogenesis of cancer and schizophrenia. We have previously reported that NRG1-stimulated migration of B lymphoblasts is PI3K-AKT1dependent and impaired in patients with schizophrenia and significantly linked to the catechol-o-methyltransferase (COMT) Val108/158Met functional polymorphism.

Research paper thumbnail of Novel Cassette-Based Shuttle Vector System for Gram-Positive Bacteria

Applied and Environmental Microbiology, 2004

Our understanding of staphylococcal pathogenesis depends on reliable genetic tools for gene expre... more Our understanding of staphylococcal pathogenesis depends on reliable genetic tools for gene expression analysis and tracing of bacteria. Here, we have developed and evaluated a series of novel versatile Escherichia coli-staphylococcal shuttle vectors based on PCR-generated interchangeable cassettes. Advantages of our module system include the use of (i) staphylococcal low-copy-number, high-copy-number, thermosensitive and theta replicons and selectable markers (choice of erythromycin, tetracycline, chloramphenicol, kanamycin, or spectinomycin); (ii) an E. coli replicon and selectable marker (ampicillin); and (iii) a staphylococcal phage fragment that allows high-frequency transduction and an SaPI fragment that allows site-specific integration into the Staphylococcus aureus chromosome. The staphylococcal cadmium-inducible P cad -cadC and constitutive P blaZ promoters were designed and analyzed in transcriptional fusions to the staphylococcal ␤-lactamase blaZ, the Vibrio fischeri luxAB, and the Aequorea victoria green fluorescent protein reporter genes. The modular design of the vector system provides great flexibility and variety. Questions about gene dosage, complementation, and cis-trans effects can now be conveniently addressed, so that this system constitutes an effective tool for studying gene regulation of staphylococci in various ecosystems.